CA2686310C

CA2686310C - Monitoring pump efficiency

Info

Publication number: CA2686310C
Application number: CA2686310A
Authority: CA
Inventors: Bruce Alexander; Kevin Hegseth; Glenn Reiter
Original assignee: Canadian Natural Resources Ltd; Pyramid Corp
Current assignee: Canadian Natural Resources Ltd; Pyramid Corp
Priority date: 2009-11-25
Filing date: 2009-11-25
Publication date: 2011-03-15
Anticipated expiration: 2029-11-25
Also published as: CA2686310A1

Abstract

A system for the recovery of oil bearing fluid materials from an oil well is disclosed comprising a pump, a storage tank arranged to receive fluid materials from the pump, a drive unit connected to the pump for delivering a drive torque thereto to operate the pump at a corresponding operating speed, a controller for controlling the drive unit and receiving signals from sensors, a tank level sensor for sensing the level of fluid in the storage tank, the tank level sensor in communication with the controller for dispatching a tank level signal representative of the tank level, a speed sensor for sensing the operating speed of the pump, the speed sensor in communication with the controller for dispatching a speed signal representative of the operating speed, and a torque sensor for sensing the drive torque, the torque sensor in communication with the controller for dispatching a torque signal representative of the drive torque, the controller configured to calculate, at regular time intervals.

Description

MONITORING PUMP EFFICIENCY
FIELD OF THE INVENTION

100011 The present invention relates to oil wells and more particularly to methods and systems of controlling pumps used in the recovery of fluid therefrom.

DESCRIPTION OF THE RELATED ART

100021 In the production of crude oil from an oil bearing subterranean reservoirs, it is often necessary to utilize a pump to move oil from the reservoir to the surface.
This can be necessary where a lack of pressure exists in the reservoir to "push" oil from the reservoir to the surface or where the viscosity of the oil is such that no amount of native pressure within the reservoir will be sufficient to accomplish this task. In the prior art there are numerous examples of the use of pumps of varying kinds and configurations to draw oil from an oil bearing subterranean reservoir to the surface through a well bore. In utilizing a pump in the production of crude oil from a well, a conventional approach is to maximize the amount of production from the well over the economic life of the well and to maximize the volume of oil being produced from the well over any measured period of time (also known as "production flow rate").
Achieving these two objectives is a matter of controlling the rate and/or frequency at which the pump pulls fluid from the reservoir. A significant problem with the use of pumps for this purpose is the potential for the pump to operate at a rate faster than the reservoir can provide fluid to the well bore. This is known as -'pump off'. Achieving the objectives of maximizing production of a well over its economic life, and maximizing the production flow rate while avoiding pump off requires the careful control of the pump to optimize pump operation. Generally, the principle is to adjust the operation of a pump to reflect changes in the well, caused by changes in the flow of fluid from the oil bearing subterranean reservoir into the well bore. Of course, adjustments can't occur without an ability to detect those changes in the recovery rate.
Common detection techniques include sensing torque at the pump, sensing flow rates in a production line, measuring a level of fluid level change in a storage tank and sensing a level of fluid in a well bore. All of these are aimed at detecting a change in flow of fluid from the oil bearing subterranean reservoir into the CNR-MPL/CDA I

well bore. The operation of the pump is then adjusted, either by way of its "duty cycle" or by its speed, so that when the recovery rate decreases, so does the duty cycle or speed of the pump and vice versa.

100031 While these developments can be beneficial to producing oil from a well, there remain several shortcomings of conventional approaches, particularly related to the recovery of oil from an oil-bearing reservoir containing or carrying sediment or solid material. A
significant number of the oil producing reservoirs of North Eastern Alberta Canada are composed of packed, compressed but otherwise loose or unconsolidated sands. The crude oil in these reservoirs is particularly viscous and will not flow to the surface through a well bore without the aid of a pump. The viscous nature of this crude oil also makes it ideal for moving the unconsolidated sands along with the crude oil as it is produced from the reservoir, thus producing sand along with the oil. The common approach to pumping this viscous crude oil from its native reservoir is to use a progressive cavity pump.

100041 A progressive cavity pump may also be also known as a progressing cavity pump, eccentric screw pump and cavity pump. This type of pump transfers fluid by means of the progress, through the pump, of a sequence of small, fixed shape, discrete cavities, as its rotor is turned. The rotor is shaped much like a corkscrew and set in a housing lined with an elastomer shaped into cavities which are a mirror image for the rotor and forms the stator. Rotating the rotor leads to the volumetric flow rate being proportional to the rotation rate (bidirectionally) and to low levels of shearing being applied to the pumped fluid. Hence these pumps have application for pumping of viscous materials.
The cavities of the stator taper down toward their ends and overlap with their neighbors, so that, in general, no flow pulsing is caused by the arrival of cavities at the outlet, other than that caused by compression of the fluid or pump components.
100051 Although a progressive cavity pump will tolerate fluid containing or carrying solids, the sands contained and carried in the viscous crude oil produced from the above described reservoirs are extremely abrasive and cause wear on the pump, in particular on the stator, thus reducing the operating life and efficiency of the pump. As shown in the prior art, this abrasion or wear is greatly accelerated when the rotor of the pump is rotated at higher speeds. Unless pump speed is adjusted to account for the production of sand with the oil, the resulting premature or accelerated wear of the pump may result in more frequent downtime and repairs, thus increasing the cost of producing crude oil from the well which the pump serves.
100061 It is also a characteristic of this type of reservoir for the proportion of sand produced with the oil to vary significantly and somewhat unpredictably during the pumping of fluid from the reservoir through a well bore. At times, high concentrations of sand can be pulled along with the crude oil, resulting in the pump over torquing resulting in damage to the pump and potentially seizing up the pump. Should this occur, the pump must be pulled from the well bore, both the pump and well bore cleaned of accumulated sand, the pump repaired or replaced and then the repaired or replaced pump returned to the well bore.

100071 Conventional approaches teach the maximizing of production flow rate while avoiding pump off. They do not take into consideration wear and tear on the pump or frequency of pump breakdown which leads to increased production costs, Nor do they address the pumping of fluid containing or carrying abrasive solids which may vary unpredictably in concentration causing pump damage or seizing, resulting in increased production costs and possible reservoir damage. Due to the abrasive nature of the sand produced with crude oil from a reservoir comprised of an unconsolidated sand, a system or apparatus designed to maximize production volume over time, while avoiding pump off, may not respond to the presence of, or changes in, the concentration of'such abrasives in sufficient time to prevent damage or degradation to the pump.

100081 Finally, the teachings of the prior art do not address maximizing of the aggregate amount of oil produced from of an oil well producing from an unconsolidated sand reservoir, over the economic life of well- The production of sand with the crude oil from this type of reservoir is essential to the overall productivity of the well as the removal of sand from the reservoir forms a network of channels, commonly known as "wormholes" from the well bore tracking off into the reservoir. These wormholes are essential to the successful production of oil from the reservoir as they form from and facilitate the production of sand from the reservoir thereby providing channels in the reservoir allowing oil contained in the reservoir to flow or be drawn into the well bore thus allowing the well bore to gain access to a large area and volume of the reservoir and the oil contained therein. The network is initiated during the initial production of the well (as evidenced by initial higher volumes of sand production), but the network continues and must continue to grow throughout the life of the well if the well is to remain productive. The effect of the wormhole network is to both allow oil contained in the reservoir to flow to the well bore and extend the reach of the well bore into the formation containing the heavy oil as each wormhole acts like a conduit allowing fluid to flow to the well bore. However these wormholes cease to grow if the pump contained within the well bore ceases to operate for any extensive period of time. They may also collapse or plug with sand. If the pump contained within the well bore ceases to operate for an extensive period of time it is very difficult re-establish the growth of the wormhole network and replace or re-open plugged or collapsed wormholes. Re-starting a well bore pump that has not been operating for an extensive period of time usually results in the production of further significant volumes of sand without necessarily a corresponding increase or re-establishment of oil production at the level enjoyed prior to the pump ceasing to operate. As a result, the overall productivity of a well in terms of the volume of oil that can be produced from the well over its economic lifetime can be negatively impaired.

100091 What is required is a means not presently taught in the art which would facilitate the control and operation of a progressive cavity pump serving a well producing oil from an unconsolidated sand reservoir in order to:

= reduce, if not minimize, the frequency of repairs and downtime for the pump;
and = increase, if not maximize, the aggregate amount of oil produced from the well that the pump serves over the economic life of the well.

SUMMARY OF THE GENERAL INVENTIVE CONCEPT

100101 In a first exemplary embodiment, there is provided a system for controlling a pump used in the recovery of oil bearing fluid materials from such a well. The system comprises a progressive cavity pump, a storage tank arranged to receive fluid materials from the pump and a drive unit connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed. The drive unit is operable to vary the pump speed by one or more preset pump speed increment values. A controller is provided for controlling the drive unit, and a tank level sensor is in communication with the controller. The tank level sensor is provided for sensing the level of fluid in the storage tank. The tank level sensor is arranged to dispatch a tank level signal representative of the fluid level in the tank. A speed sensor is provided for sensing the pump speed, in one example in revolutions per minute.
The speed sensor is also in communication with the controller for dispatching a speed signal representative of the pump speed. Also provided is a torque sensor for sensing the drive torque. The torque sensor is also in communication with the controller for dispatching a torque signal representative of the drive torque. The controller is configured to calculate and monitor a pump efficiency value for changes in pump efficiency and to vary the pump speed according to the pump efficiency value. To this end, the controller is configured to receive into memory:

- a preset minimum pump efficiency value;
- a preset pump speed increment value;

- a preset sampling time interval for collecting data from the tank level and speed sensors;
- a preset maximum torque setting;

- a preset minimum pump speed;

- a preset torque override bypass slowdown time interval - a preset maximum pump speed; and - a preset manufacturer's pump rating value for the pump.

100111 In the first exemplary embodiment, these presets are entered into the controller, directly or indirectly, by a human operator or through an interface with a computer system. The preset manufacturer's pump rating value is an ideal volume of fluid that the pump should produce at a prescribed ideal operating speed over a given period of time. In one example, the preset minimum pump efficiency value is a fraction of the manufacturer's pump rating value, selected based on experience with the production history of the oil bearing subterranean reservoir. This value is presumed to be a minimum economic efficiency for producing fluid from the oil bearing subterranean reservoir from the wellbore in question. The preset maximum and minimum pump speeds are selected based on experience with the production history of the oil bearing subterranean reservoir. In one example, the maximum speed is presumed to be the highest speed at which the pump can operate, without encountering pump off. In one example, the minimum speed is presumed to be the lowest speed at which the pump can operate, while still producing fluid from the reservoir, even where such fluid production includes high volumes of sand, though there may be instances in which the pump may operate below the minimum speed. The preset maximum torque setting is the maximum amount of torque that the drive unit can impose on the pump before damage to or seizing of the pump may occur.

100121 In the first exemplary embodiment, the preset pump speed increment value is a speed change (in one example measured in revolutions per minute (RPM)), selected based on experience with the production history of the oil bearing subterranean reservoir. The preset speed increment is used for both positive and negative changes in pump speed in most circumstances. The preset sampling time interval is selected based on experience with the production history of the oil bearing subterranean reservoir, in one example, as a balance between the expected minimum time required for obtaining an effective determination of changes in pump operating efficiency and the maximum time that the pump can be allowed to operate free of intervention without incurring significant risk of damage to the pump. The preset torque override bypass slowdown time interval is selected based on experience with the type of pump and drive unit being used and is usually a duration of time shorter than the preset sampling time interval. An over torque condition is usually caused by a sudden increase in the amount of sand being drawn from the reservoir with the oil bearing fluid. Each step change in pump speed is employed to address the over torque condition. A short period of time may thus be required to allow the pump the opportunity to clear this sudden increase in the amount (or "slug") of sand before varying the speed if the over torque condition does not resolve itself.

100131 In the first exemplary embodiment, the controller is further configured, after a first operational time period:

a) to receive the tank level signal and to determine therewith a first tank level;
CNR-MPFiCDA 6 b) and, with the first tank level, to determine a first change in tank level over the first preset sampling time interval;

c) and, with the first change in tank level, to calculate a first volume of fluid collected over the first preset sampling time interval;

d) to receive the speed signal to determine therewith a first pump speed, e) and, with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, to calculate a first pump efficiency value;

1) to compare the first pump efficiency value with the preset minimum pump efficiency value:

g) arid, if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, to increase the pump speed by the preset pump speed increment value;
h) and if the first pump efficiency value is less than the preset minimum pump efficiency value, to decrease the pump speed by the preset pump speed increment value;

i) and to repeat steps a) through h) at the end of each sampling time interval thereafter.
100141 In the first exemplary embodiment, the controller is further configured to override other functions of the control system if the torque sensor registers a torque exceeding the preset maximum torque setting, and to decrease the speed of the pump by the preset pump speed increment value initially to decrease the speed of the pump by the preset pump speed increment value and then, at the end of each preset torque override bypass slowdown time interval, until:

- the torque sensor registers a torque less than the preset maximum torque setting, and thereby to return pump control system to full normal operation; or - the pump speed is reduced to zero.

100151 In some exemplary embodiments, the preset minimum pump efficiency value is calculated as the measured pump efficiency, expressed as a percentage preset manufacturer's pump rating value for the pump. In one example, the controller is configured to add an operational variance factor to the preset minimum pump efficiency value. The operational variance factor is applied to gross up the minimum pump efficiency value and is used where the controller is configured to reduce pump speed by the preset pump speed increment value at the end of any preset sampling time interval where the measured pump efficiency value is greater than the preset minimum pump efficiency value but less than the preset minimum pump efficiency value plus the operational variance factor. In this configuration the controller reduces the pump speed to the preset minimum pump speed if, for two consecutive preset sampling time intervals, the measured pump efficiency value is less than the preset minimum pump efficiency value.
100161 In another exemplary embodiment, there is provided a system for the recovery of oil bearing fluid materials from an oil well, comprising (i) a progressive cavity pump;

(ii) a storage tank arranged to receive fluid materials from the pump;

(iii) a drive unit connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed, with the drive unit operable to vary the pump speed;
(iv) a controller;

(v) a tank level sensor in communication with the controller, for sensing the level of fluid in the storage tank, with the tank level sensor configured for dispatching a tank level signal representative of the tank level;

(vi) a speed sensor in communication with the controller for sensing the pump speed, with the speed sensor configured for dispatching a speed signal representative of the pump speed;
(vii) a torque sensor in communication with the controller for sensing the drive torque, with the torque sensor configured for dispatching a torque signal representative of the drive torque;
and (viii) the controller configured for receiving the tank level signal, the speed signal and the torque signal, respectively, from the tank level sensor, the speed sensor and the torque sensor, and for controlling the drive unit to vary the speed of the pump by one or more preset pump speed increment values, the controller configured to calculate a pump efficiency value and to monitor torque for changes in pump efficiency and torque, and to vary the pump speed CNa-MPF/CDA 8 according to the pump efficiency value and torque, the controller configured to receive into memory:

- a preset manufacturer's pump rating value for the pump;
- a preset minimum pump efficiency value;

- a preset pump speed increment value;

- a preset sampling time interval for collecting data from the tank level and speed sensors;
- a preset maximum torque setting;

- a preset torque override bypass slowdown time interval:
- a preset minimum pump speed; and - a preset maximum pump speed; and at the end of a first preset sampling time interval, the controller further configured:

a) to receive the tank level signal and to determine therewith a first tank level;

b) with the first tank level, to determine a first change in tank level over the first sampling time interval;

c) and, if the tank level change is positive, to calculate a first volume of fluid collected over the first sampling time interval;

d) to receive the speed signal to determine therewith a first pump speed;

e) and, with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, to calculate a first pump efficiency value;

f) to compare the first pump efficiency value with the preset minimum pump efficiency value;

g) and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, to increase the pump speed by the preset pump speed increment value;
h) and if the first pump efficiency value is less than the preset minimum pump efficiency value, to decrease the pump speed by the preset pump speed increment value;

i) and to repeat steps a) through h) at the end of each sampling time interval thereafter;
j) to receive the torque signal from the torque sensor;

k) and if the torque signal exceeds the preset maximum torque setting, to override steps g) and h) and to decrease the speed of the pump by the preset pump speed increment value and, I) to repeat steps j) and k) at the end of each preset torque override bypass slowdown time interval until:

i) the torque sensor registers a torque less than the preset maximum torque setting , thereby returning to step a); or ii) the pump speed is reduced to zero.

100171 In some exemplary embodiments, the pump efficiency value is calculated as the measured pump efficiency expressed as a percentage of a rated pump efficiency.

100181 In some exemplary embodiments, the controller is configured to add an operational variance factor to the preset minimum pump efficiency value, the controller further configured to reduce the pump speed by the preset pump speed increment value where, at the end of any preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, and the controller further configured to reduce the pump speed to the preset minimum pump speed where, at the end of each of at least two consecutive preset sampling time intervals, the calculated pump efficiency value is less than the preset minimum pump efficiency value.

100191 In some exemplary embodiments, the controller is configured to add an operational variance factor to the preset minimum pump efficiency value, the controller further configured to make no change to the pump speed where at the end of any preset sampling time interval the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, and the controller further configured to reduce the pump speed to the preset minimum pump speed where, at the end of each of two consecutive ('NR-MPI./CDA 10 preset sampling time intervals, the calculated pump efficiency value is less than the preset minimum pump efficiency value.

100201 In some exemplary embodiments, the drive unit includes a drive train for driving the pump, the drive train including a drive motor. The drive motor may include an internal combustion engine, an electrical drive motor, and/or an hydraulic drive motor.

100211 In some exemplary embodiments, the first pump efficiency value is calculated according to the formula: PIE= [(Vt / St)/(Vr/Sr)] 100, where:

- Vt is a volume of fluid collected in the tank in a predetermined sampling time interval, adjusted to a 24 hour period;

- St is a pump speed during the predetermined sampling time interval, expressed in RPM;

- Sr is a manufacturer's rated pump speed, expressed in RPM; and - Vr is a rating for volume produced in a rated time interval adjusted to a 24 hour period.

100221 In some exemplary embodiments, the predetermined sampling time interval is one hour, though other time intervals may be employed, as desired.

100231 In some exemplary embodiments, the preset torque override bypass slowdown time interval is a fraction of the preset sampling time interval. In one example, the fraction is one quarter to one half, 100241 In some exemplary embodiments, the preset speed increment value is 5 RPM, though other speed increments may also be used as desired.

100251 In some exemplary embodiments, the pump is driven by hydraulic fluid in a supply line from an external hydraulic pump and the preset maximum torque setting ranges from about 2500 psi to 2900 psi, which reflects the pressure exerted in the hydraulic fluid used to drive the pump.

100261 In some exemplary embodiments, the pump is driven by an electric motor and the preset maximum torque setting ranges from about 35 amps to about 45 amps, which reflects the amperage draw of the electric motor used to drive the pump.

100271 In some exemplary embodiments, the preset pump efficiency value ranges from 25 percent to 80 percent.

100281 In some exemplary embodiments, the preset maximum pump speed is set according to a rated maximum pump speed.

100291 In some exemplary embodiments, the present minimum pump speed is set to maintain a minimum recovery flow of fluid from the well.

100301 In some exemplary embodiments, the controller is configured so that the controller does not increase pump speed beyond the preset maximum pump speed and does not reduce the pump speed below the preset minimum pump speed.

10031 In another exemplary embodiment, there is provided an oil field control installation, comprising a plurality of oil wells, each being independently controlled by the system as defined above.
100321 In another exemplary embodiment, there is provided a computer-implemented method of controlling an oil well, comprising:

a. providing a progressive cavity pump in a well bore of the oil well;
b. providing a storage tank to receive fluid materials from the pump;
('NR-MPE/CUA 12 c. providing a pump drive section connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed;

d. configuring the pump drive section to receive instructions to increase speed by one or more preset pump speed increment values;

C. providing a tank level sensor for sensing the level of fluid in the storage tank and a speed sensor for sensing the pump speed:

f. receiving signals from the tank level sensor and the speed sensor indicative of tank level and pump speed respectively;

g. providing a torque sensor for sensing a drive torque value delivered by the pump drive section to the pump;

h. receiving signals from the torque sensor indicative of drive torque the torque;

i. monitoring a pump efficiency value for changes in pump efficiency and to vary the pump speed according to the pump efficiency value, including:

1. receiving into memory:

a. a preset minimum pump efficiency value;
b. a preset pump speed increment value;

c. a preset sampling; time interval for collecting data from the tank level and speed sensors;

d. a preset maximum torque setting;

e. a preset torque override bypass slowdown time interval;
f. a preset minimum pump speed;

g. a preset maximum pump speed; and h. a preset manufacturer's pump rating value for the pump;
II. and, after a first preset sampling time interval:

a. receiving the tank. level signal and determining therewith a first tank level;

b. with the first tank level, determining a first change in tank level over the first preset sampling time interval;

CNR-MPfi/CDA 13 c. with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

d. receiving the speed signal to determine therewith a first pump speed;
e. with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

f. comparing the first pump efficiency value with the preset minimum pump efficiency value;

g. and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value , increasing the pump speed by the preset pump speed increment value;

h. and if the first pump efficiency value is less than the preset minimum pump efficiency value, decreasing the pump speed toward the preset minimum pump speed; and i. and to repeat steps a. through h. at the end of each sampling time interval thereafter;

j. and if, during steps a. to h., the torque sensor registers a torque exceeding the preset maximum torque setting, overriding other functions of the control system and decreasing the speed of the pump by the preset pump speed increment value initially and then at the end of each preset torque override bypass slowdown time interval. until:

- the torque sensor registers a torque less than the preset maximum torque setting and then to return the pump control system to full normal operation; or - the pump speed is reduced to zero.

100331 In yet another exemplary embodiment, there is provided a computer-implemented method of controlling an oil well, comprising:

CN R-M PI :/C DA 14 a. providing a progressive cavity pump in a well bore of the oil well, b. providing a storage tank to receive fluid materials from the pump;

c. providing a pump drive section connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed;

d. configuring the pump drive section to receive instructions to vary the pump speed by one or more preset pump speed increment values;

e. receiving signals from a tank level sensor and a speed sensor indicative of tank level and pump speed respectively;

f. receiving signals from a torque sensor indicative of the drive torque;

g. monitoring a pump efficiency value for changes in pump efficiency and to vary the pump speed according to the pump efficiency value, including:

1. receiving into memory:

a. a preset manufacturer's pump rating value for the pump;
b. a preset minimum pump efficiency value;

c. a preset pump speed increment value;

d. a preset sampling time interval for collecting data from the tank level and speed sensors;

e. a preset maximum torque setting:

f. a preset torque override bypass slowdown time interval:
g. a preset minimum pump speed; and h. a preset maximum pump speed; and 11. after a first preset sampling time interval:

a. receiving the tank level signal and determining therewith a first tank level:

b. with the first tank level, determining a first change in tank level over the first preset sampling time interval;

c. with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

('NR-MP[/CD.A 15 d. receiving the speed signal to determine therewith a first pump speed;
e. with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

f. comparing the first pump efficiency value with the preset minimum pump efficiency value.

g. and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, increasing the pump speed by the preset pump speed increment value, h. and if the first pump efficiency value is less than the preset minimum pump efficiency value, decreasing the pump speed toward the preset minimum pump speed; and i. and to repeat steps a) through h) at the end of each sampling time interval thereafter;

j. and if the torque sensor registers a torque exceeding the preset maximum torque setting, to override other functions to decrease the speed of the pump by the preset pump speed increment value;

k. to repeat step j) at the end of each preset torque override bypass slowdown time interval until:

i) the torque sensor registers a torque less than the preset maximum torque setting and then return to step a); or ii) the pump speed is reduced to zero.

100341 In some exemplary embodiments, step II h) includes decreasing the pump speed by the preset pump speed increment value.

100351 In yet another exemplary embodiment, there is provided a computer-implemented method of controlling an oil well, comprising:

('NR-MP[;/CDA 16 a. providing a progressive cavity pump in a well bore of the oil well;
b. providing a storage tank to receive fluid materials from the pump;

c. providing a pump drive section connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed:

d. configuring the pump drive section to receive instructions to increase speed by one or more preset pump speed increment values;

e. receiving signals from a tank level sensor and a speed sensor indicative of tank level and pump speed respectively;

f. receiving signals from a torque sensor indicative of the drive torque;

g. monitoring a pump efficiency value for changes in pump efficiency and to vary the pump speed according to the pump efficiency value, including:

1. receiving into memory:

a. a preset manufacturer's pump rating value for the pump;
b. a preset minimum pump efficiency value;

c. a preset pump speed increment value:

d. a preset sampling time interval for collecting data from the tank level and speed sensors;

e. a preset maximum torque setting;

f. a preset torque override bypass slowdown time interval;
g. a preset minimum pump speed; and h. a preset maximum pump speed;

11. and, after a first preset sampling time interval:

a. receiving the tank level signal and determining therewith a first tank level;

b. with the first tank level, determining a first change in tank level over the first preset sampling time interval;

c. with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

CNR-MPF./CDA 17 d. receiving the speed signal to determine therewith a first pump speed;
e. with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

F. comparing the first pump efficiency value with the preset minimum pump efficiency value;

g. and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, increasing the pump speed by the preset pump speed increment value ;

h. and if the first pump efficiency value is less than the preset minimum pump efficiency value, decreasing the pump speed toward the preset minimum pump speed; and i. and to repeat steps a) through h) at the end of each sampling time interval thereafter;

j. and, if the torque sensor registers a torque exceeding the preset maximum torque setting, to override other functions to decrease the speed of the pump to zero or to the preset minimum pump speed and to maintain the pump at zero or at the preset minimum pump speed until the torque sensor registers a torque less than the preset maximum torque setting.

100361 In yet another exemplary embodiment, there is provided a computer-implemented method of controlling an oil well, comprising:

- receiving into memory:

- a preset minimum pump efficiency value;
- a preset pump speed increment value;

- a preset sampling time interval for collecting data from a tank level sensor indicative of a level of oil fluid in a tank downstream from an oil pump in the oil well, and data from a speed sensor indicative of a pump speed of the pump;

- a preset maximum torque setting for torque to be delivered to the pump;
- a preset minimum pump speed;

- a preset maximum pump speed:; and - a preset manufacturer's pump rating value for the pump;
and after a first operational time period:

- receiving a tank level signal from the tank level sensor and determining therewith a first tank level;

- with the first tank level, determining a first change in tank level over the first preset sampling time interval;

- with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

- receiving a speed signal from the speed sensor to determine therewith a first pump speed, - with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

- comparing the first pump efficiency value with the preset minimum pump efficiency value;

- and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, signaling an increase in the pump speed by the preset pump speed increment value;

- and if the first pump efficiency value is less than the preset minimum pump efficiency value, signaling a decrease in the pump speed toward the preset minimum pump speed; and collecting data from a torque sensor indicative of torque being delivered to the pump, and if the torque sensor registers a torque exceeding the preset maximum torque setting, overriding the controller and signaling a decrease in the speed of the pump to zero or to the preset minimum pump speed.

100371 In yet another exemplary embodiment, there is provided a computer-implemented method of controlling an oil well, comprising:

- receiving into memory:

- a preset minimum pump efficiency value;
- a preset pump speed increment value;

- a preset sampling time interval for collecting data from a tank level sensor, indicative of a level of oil fluid in a tank downstream from an oil pump in the oil well and data from a speed sensor indicative of a pump speed of the pump;

- a preset maximum torque setting for torque to be delivered to the pump;
- a preset torque override bypass slowdown time interval;

- a preset minimum pump speed;

- a preset maximum pump speed; and - a preset manufacturer's pump rating value for the pump;
- and, after a first preset sampling time interval:

- receiving a tank level signal from the tank level sensor and determining therewith a first tank level;

- with the first tank level, determining a first change in tank level over the first preset sampling time interval;

- with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval:

- receiving a speed signal from the speed sensor to determine therewith a first pump speed, - with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

- comparing the first pump efficiency value with the preset minimum pump efficiency value;

- and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, signaling to increase the pump speed by the preset pump speed increment value;

- and if the first pump efficiency value is less than the preset minimum pump efficiency value, signaling to decrease the pump speed toward the preset minimum pump speed; and collecting data from a torque sensor indicative of torque being delivered to the pump, and if the torque sensor registers a torque exceeding the preset maximum torque setting, overriding other operations of the controller and signaling a decrease in the speed of the pump to zero.

100381 1n yet another exemplary embodiment. there is provided a computer readable medium comprising computer-executable instructions for performing the method as defined above. In this case, the medium may include a data storage device such as a hard drive, a USB key, thumb drive, computer memory, a computer readable disk such as a Digital Video Disk (DVD) or the like.

100391 In yet another exemplary embodiment, there is provided a system for the recovery of oil bearing fluid materials from an oil well, comprising a pump, and a storage tank arranged to receive fluid materials from the pump. A drive unit is connected to the pump for delivering a drive torque thereto to operate the pump at a corresponding operating speed. A controller is provided for controlling the drive unit and receiving signals from sensors. A tank level sensor is provided for sensing the level of fluid in the storage tank and is in communication with the controller for dispatching a tank level signal representative of the tank level. A speed sensor is provided for sensing the operating speed of the pump and is in communication with the controller for dispatching a speed signal representative of the operating speed. A
torque sensor is provided for sensing the drive torque and is in communication with the controller for dispatching a torque signal representative of the drive torque. The controller is configured to calculate, at regular time intervals:

CNR-MPI:/C DA 21 - a volume of fluid collected during a regular time interval, according to changes in the tank level:

- a pump efficiency value according to the volume of fluid collected and the speed of the pump, and - a pump efficiency ratio value according to the pump efficiency value and a rated pump efficiency value for the pump.

After calculating the pump efficiency ratio, the controller is further configured to:

- increase the operating speed from a current operating speed toward a predetermined maximum operating speed, so long as the pump efficiency ratio equals or exceeds a preset minimum pump efficiency ratio value: or - decrease the operating speed from the current operating speed toward a predetermined minimum operating speed, so long as the pump efficiency ratio does not exceed a preset minimum pump efficiency ratio value.

100401 In some exemplary embodiments, the controller is also configured to receive the torque signal and to determine a torque level for the pump. If the torque level indicates that the pump is in an over torque condition, the controller is configured to override all other operations and to decrease the speed of the pump from a current operating speed to a predetermined minimum operating speed, or to zero, regardless of a previously calculated pump efficiency ratio value.

100411 In some exemplary embodiments, the controller is configured to add an operational variance factor to the preset minimum pump efficiency value, the controller is further configured to reduce the pump speed by the preset pump speed increment value where, at the end of any preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, and the controller further configured to reduce the pump speed to the preset minimum pump speed where, at the end of each of at least two consecutive preset sampling time intervals, the calculated pump efficiency value is less than the preset minimum pump efficiency value.

CNR-MPS:/CUA 22 100421 In some exemplary embodiments, the controller is configured to add an operational variance factor to the preset minimum pump efficiency value, the controller further configured to make no change to the pump speed where at the end of any preset sampling time interval the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, and the controller further configured to reduce the pump speed to the preset minimum pump speed where, at the end of each of two consecutive preset sampling time intervals, the calculated pump efficiency value is less than the preset minimum pump efficiency value.

100431 In yet another exemplary embodiment, there is provided a computer-implemented method of controlling an oil well, comprising:

a. providing a progressive cavity pump in a well bore of the oil well;
b. providing a storage tank to receive fluid materials from the pump;

c. providing a pump drive section connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed;

d. configuring the pump drive section to receive instructions to increase speed by one or more preset pump speed increment values;

e. receiving signals from a tank level sensor and a speed sensor indicative of tank level and pump speed respectively;

f. receiving signals from a torque sensor indicative of the drive torque;

g. monitoring a pump efficiency value for changes in pump efficiency and to vary the pump speed according to the pump efficiency value, including:

1. receiving into memory:

a. a preset manufacturer's pump rating value for the pump:
b. a preset minimum pump efficiency value;

c. a preset pump speed increment value;

d. a preset sampling time interval for collecting data from the tank level and speed sensors;

CNR-MPL:/CD,~ 23 e. a preset maximum torque setting;

f. a preset torque override bypass slowdown time interval:
g. a preset minimum pump speed; and h. a preset maximum pump speed;

II. and, after a first preset sampling time interval:

a. receiving the tank level signal and determining therewith a first tank level, b. with the first tank level, determining a first change in tank level over the first preset sampling time interval;

c. with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

d. receiving the speed signal to determine therewith a first pump speed;
e. with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value:

f. comparing the first pump efficiency value with the preset minimum pump efficiency value;

g. and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, increasing the pump speed by the preset pump speed increment value:

h. and if the first pump efficiency value is less than the preset minimum pump efficiency value, decreasing the pump speed toward the preset minimum pump speed; and i. and to repeat steps a) through h) at the end of each sampling time interval thereafter:

j. and if the torque sensor registers a torque exceeding the preset maximum torque setting, to override other functions of the control system and to decrease the speed of the pump by the preset pump speed increment value :, k. to repeat step j) at the end of each preset torque override bypass slowdown time interval until:

i) the torque sensor registers a torque less than the preset maximum torque setting and then return to step a); or ii) the pump speed is reduced to zero.

100441 Some exemplary embodiments further comprise, in section 1, receiving into memory:
i. an operational variance factor, and further comprise, in section 11 after step k:

1. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, decreasing the pump speed by the preset pump speed increment value; and in. if, at the end of a first preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value, making no change to the pump speed; and n. if, at the end of a second consecutive preset sampling time interval, the calculated pump efficiency value is still less than the preset minimum pump efficiency value, reducing the pump speed to the preset minimum pump speed.

100451 Some exemplary embodiments further comprise, in section I, receiving into memory:
i. an operational variance factor, and further comprise, in section 11 after step k:
CN R-MPG/C DA ') 5 1. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, making no change to the pump speed;
and M. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value reducing the purnp speed to the preset minimum pump speed.

100461 Some exemplary embodiments further comprise, in section 1, receiving into memory:
i. an operational variance factor, and further comprise, in section II after step k:

1. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, making no change to the pump speed;
and m. if, at the end of a first preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value making no change to the pump speed; and n. if, at the end of a second consecutive preset sampling time interval, the calculated pump efficiency value is still less than the preset minimum pump efficiency value, reducing the pump speed to the preset minimum pump speed.

100471 Thus, in some exemplary embodiments, a system is provided which maintains continuous operation of a pump operating in a well bore of a well producing oil and associated substances from an oil bearing subterranean reservoir, while protecting the pump from excessive wear, or seizing.

CNR-MPI:/CDA 26 BRIEF DESCRIPTION OF THE DRAWINGS

100481 Several preferred embodiments of the present invention will be provided, by way of examples only, with reference to the appended drawings, wherein;

100491 Figure l is a schematic view of a well installation; and 100501 Figures 2 and 3a to 3c are flow diagrams of a protocol for the operation of the pump comprising part of the well installation of figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

100511 It should be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms "connected," "coupled," and "mounted," and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms "connected" and "coupled" and variations thereof are not restricted to physical or mechanical connections or couplings. Furthermore, and as described in subsequent paragraphs, the specific mechanical configurations illustrated in the drawings are intended to exemplify embodiments of the invention. However, other alternative mechanical configurations are possible which are considered to be within the teachings of the instant disclosure.
Furthermore, unless otherwise indicated, the term "or" is to be considered inclusive. The term "a" when followed by a single recitation of a named feature is to be construed inclusively, to mean that it includes within its meaning, more than one of the named feature, or more than one feature including the named feature.

CNR-MPF./CDA 27 100521 Figure 1 illustrates, schematically, an oil recovery installation 10 comprised of a number of individual oil well sites 12, which in this example, for the sake of illustration, number three. That being said, a typical oil recovery installation may involve an oil field with hundreds of well sites 12. Each well site 12 includes an oil well 14 which has been drilled from the surface into a geological formation containing oil bearing fluid materials, such oil well having with an inner well bore 14a provided by a well casing 16 extending into the ground and ending at or near a geological formation 18 containing oil bearing fluid materials. One such geological formation 18 is made up of an unconsolidated sand matrix with oil fluid (or fluids) contained in interstitial spaces or entrained with the sand therein, though the devices and methods disclosed herein may be applied to other geological formations, as desired. The oil fluid drawn from the oil well 14, of this example, will include an entrained sand constituent, as well as brine and oil emulsion contained in the geological formation. As entrained sand is carried with oil fluid drawn from the sand matrix, channels (known in the trade as "worm holes") tend to form and interconnect outwardly from the well bore and these will randomly widen, lengthen and join one another, as a flow of oil fluid is first formed in the matrix and then as oil fluid flows through these ever-changing channels. As the channels change, unconsolidated sand and other materials from the matrix are thus further released into, and carried with, the oil fluid flow.

100531 A progressive cavity pump 20 is located in the inner well bore 14a of the oil well 14, with an inlet portion 22 located down hole and an outlet portion 24 which is joined, by way of a fluid line shown at 26, to a storage tank 28. A drive train 30 including an hydraulic drive head motor 32 mounted on top of the well and connected mechanically to the pump 20 and a motive power source, either electric, hydraulic or mechanical. delivers a drive torque to drive the pump 20 at a corresponding operating speed. In this case, the drive train 30 is operable, in one operating phase, to vary (that is, increase or decrease) the pump speed by one or more preset pump speed increment values, and, in another operating phase, to roll back the pump speed. The drive train 30 is exemplified, in part, by the hydraulic drive head motor 32, driven by an hydraulic pump 34 via hydraulic fluid lines shown at 34a, 34b. In turn, the hydraulic pump 34 is driven by a drive motor 36, such as an internal combustion engine, an electrical motor or the like. The drive train 30 in turn communicates with a controller shown at 38 via data path 36a.

100541 The progressive cavity pump includes a rotor portion 20a with a helical shaped section set within a housing lined with an elastomer in which is formed a mirror image of the helical section of the rotor, and acts as a stator portion 20b. The stator portion 20b thus offsets the helical shaped rotor portion of rotor 20a, so that the engagement of the rotor and stator portions 20a, 20b by rotating the rotor forms a series of helical cavities between the stator portion 20b and the helical section of the rotor portion 20a.
Rotation of the rotor portion 20a, relative to the stator portion 20b in one direction, therefore causes the oil fluid in the cavities to progress upwardly from the inlet portion 22 to the outlet portion 24. To maintain an effective seal in the helical cavity, it is necessary that an effective seal be established between the helical sections of the rotor portion 20a and stator portion 20b, which is typically provided by low friction materials on one or both thereof. The presence of sand in the oil fluid increases friction between the rotor and stator portions 20a, 20b which increases the torque needed to continue operation of the pump.

100551 The controller 38 is provided for controlling the drive train 30 in response to changes in pump efficiency, as will be described below. In this case, the controller 38 includes a computer screen, a keyboard or keypad, one or more processors, for example one or more programmable logic controllers (PLC's) 40, one or more hard drives, as well as one or more memory chips, and one or more network interface ports, as needed, to couple with data paths 36a, 48a, 50a and 52a (as will be described below).
The controller 38 is part of a communication network 42, such as the Internet or a configured intranet, via data path 38a in order to communicate with a central station shown at 44. The controller 38, the communication network 42 and the central station 44 may be part of a larger oil field control system, such as that well known as Supervisory Control and Data Acquisition or SCADA.

100561 The controller 38 may, alternatively, be computer implemented in a number of forms, by way of one or more software programs configured to run on one or more general purpose computers, such as a personal computer. The system may, alternatively, be executed on a more substantial computer mainframe. The general purpose computer may work within a network involving several general purpose computers, for example those sold under the trade names APPLE or IBM, or clones thereof, which are programmed with operating systems known by the trade names WINDOWS, LINUX or other well known CNR-MPFICL)n 29 or lesser known equivalents of these. The system may involve pre-programmed software using a number of possible languages or a custom designed version of a programming software.
The computer network may be include a wired local area network, or a wide area network such as the Internet, or a combination of the two, with or without added security, authentication protocols, or under "peer-to-peer" or "client-server"
or other networking architectures. The network may also be a wireless network or a combination of wired and wireless networks. The wireless network may operate under frequencies such as those dubbed `radio frequency' or "RF" using protocols such as the 802.1 1, TCP/IP, BLUE TOOTH and the like, or other well known Internet, wireless, satellite or cell packet protocols.

10057 A graphical user interface (GUI) 46 is also provided to allow for local programming and for setting of default values for the operation of controller 38, via data path 46a. The GUI 46 may include a computer implemented terminal interface, with a computer screen, a keyboard or keypad, one or more processors, memory, one or more hard drives and network interface ports or the like as required to allow for communication between the GUI 46 and the controller 38, for inputting data and for making user settings. Alternatively, the GUI 46 may take the form of a software application running on a general purpose computer which, via one or more remote telemetry protocols, provides remote communication with and control of the controller 38.

100581 The storage tank 28 is provided with a tank level sensor 48 for sensing the level of fluid therein. In this case, the tank level sensor is a pressure sensor, such as that commercially available under the trade name FOXBORO by INVENSYS PROCESS SYSTEMS. The tank level sensor is in communication with the controller 38 via data path 48a for dispatching a tank level signal representative of the tank level, in other words the height of the fluid in the storage tank. In this case, the tank is shown to be partially filled with oil fluid which has separated out by dens ity/specif ic gravity, with the lowermost layer containing the sand and other relatively dense constituents. A central layer includes the groundwater constituent while the upper layer contains the oil constituent. In this case, the tank level sensor is located generally in the lower portion of the upper layer so as to monitor tank levels in the upper layer, though the ('NR-MPP,/CDA 30 sensor may be placed at other elevations as desired. Other techniques to measure tank level may also be used as desired.

100591 A speed sensor 50 is also provided on drive train 30, for sensing the operating speed of the pump 20 by measuring the flow of hydraulic fluid in the hydraulic supply line 34a. One example of the speed sensor is commercially available under the trade name BLANCETT TURBINE
FLOW METER by RACINE FEDERATED INC. The speed sensor 50 is in communication with the controller 38, via data path 50a, for dispatching a signal representative of the flow of hydraulic fluid to the drive head 32, for conversion to a quantity which is representative of pump speed in revolutions per minute. Alternatively, the speed sensor 50 may include a processing function to calculate the pump speed and to dispatch a pump speed signal to the controller 38. Other speed sensors may be used as desired.

100601 A torque sensor 52 is also provided on the drive train 30 for sensing the drive torque exerted on the pump 20 by measuring the supply pressure in the hydraulic supply line 34a. One example of the torque sensor is commercially available under the trade name ECO I by WIKA INSTRUMENT
CORPORATION. The torque sensor 52 is in communication with the controller 38, via data path 52a, for dispatching a signal representative of the pressure in hydraulic supply line 34a, for conversion to a quantity which is representative of the drive torque. In this case, the controller 38 is operable to detect increases in torque by fluctuations in the hydraulic supply pressure. Alternatively, the torque sensor 52 may include a processing function to calculate the drive torque and to dispatch a drive torque signal to the controller 38.
In this case, the drive torque is one example of a load being exerted on, or being generated by, the pump 20.
Other loads may be also be monitored, as represented by heat, pressure, strain and the like.

100611 The controller 38 is configured to carry out a pump monitoring and control protocol based on a pump efficiency value, where changes in pump speed are made according to pump efficiency.
Each pump is provided with a rating by the manufacturer that specifies a volume of fluid that can be produced by the pump at a specified pump speed (in this case in RPM) over a specified period of time under ideal conditions. This manufacturer's pump rating value is deemed to represent an ideal 100%

efficiency value for the pump. Measured pump efficiency is thus calculated against this ideal efficiency value and is determined by the formula: PE _ [(Vt / St)/(Vr/Sr)] 100, where:

Vt is the volume of fluid collected in the tank 28 in a predetermined sampling time interval, adjusted to a 24 hour period;

St is pump speed during the predetermined sampling time interval, expressed in RPM;

Vr is a rating provided by the manufacturer for a volume of fluid produced in a rated time interval, adjusted to a 24 hour period; and Sr is the manufacturer's rated pump speed, expressed in RPM required to produce Vr.

100621 Thus, in one example, the performance of the pump 20 is measured by a calculation of volume of oil fluid pumped during a particular sampling time period, such as a one hour period, at a measured pump speed and then converted to an effective volume of oil fluid pumped over a 24 hour period, which is then compared against the manufacturer's rating value for the pump and expressed as a percentage. This formula thus measures the performance of the pump, as an efficiency value based on its actual performance against its manufacturer's rating value which is deemed to be the point at which the pump 20 is operating at 100 percent efficiency. Other sampling time intervals may be used as desired.
100631 An aim of this protocol is to maximize the flow of oil fluid per pump revolution.
Maximizing the "flow of oil fluid per pump revolution" does not necessarily mean operating the pump at maximum speed. "As the rotor turns inside the stator, fluid moves through the pump from cavity to cavity.
As one cavity diminishes, the opposing cavity increases at exactly the same rate which results in a pulsationless positive displacement flow through the pump. The cavities are separated from each other by a series of seal lines which are created between the rotor and stator." (SPE
paper #37455 Progressive Cavity(PC) Pump Design Optimization for Abrasive Applications) Seeking to maximize the gross flow of oil fluid in a given time frame may result, in some cases, in a reduction in the amount of fluid produced per pump revolution. This can in turn lead to premature wear or damage to the pump and result in inefficient operation of the pump. As the fluid being pumped from an oil bearing unconsolidated sand reservoir carries abrasive materials in the form of fine sand in varying quantities, higher pump speeds, although they may temporarily translate into higher total volumes of fluid produced, may result in more rapid wear of the pump and more frequent need to service and replace the pump. "Abrasive wear of progressive cavity pumps is one of the most common modes of failure. High speed particles (sand) traveling through pump cavities abrade both rotor and stator.
This causes the seal lines between the rotor and stator to become less effective and results in higher pump slippage. The increase in the pump slippage will reduce pump volumetric efficiency and will gradually destroy the pump" (SPE paper #37455 Progressive Cavity(PC) Pump Design Optimization for Abrasive Applications). Therefore, by focusing on volume of fluid produced per unit speed (in this case RPM) or pump efficiency, pump wear caused by operation at excessive pump speeds may be detected much more readily and rapidly than by focusing on gross volume of fluid produced over time.

100641 Therefore, the operational life of the pump may be extended to reduce the frequency and duration of time that the pump has to be stopped, removed, repaired or replaced. Thus, in this case, a degree of protection is afforded the pump to reduce the rate of wear and the frequency of breakdown, while preserving and maintaining continuous operation of the pump for a relatively longer period of time in order to maximize and maintain the growth of the channels developed in the reservoir resulting from the continuous production of sand with the fluid produced by pumping such fluid from the reservoir.

100651 Another feature in the exemplified protocol of the controller 38 (as will be described more fully below) is the detection of pump-off conditions and the reduction in the risk of pump-off conditions occurring. For detecting pump off, monitoring pump efficiency is at least as effective as monitoring volume of fluid produced over time. However, as an embodiment of the exemplified protocol is the operation of the pump at a lower RPM setting than would otherwise occur if the pump were operated to maximize gross production over time, the likelihood of pump-off occurring is greatly reduced.

100661 Another feature in the exemplified protocol of the controller 38 is the sensing of torque, and the implementation of a speed reduction procedure, as an override to the other monitoring and speed varying functions of the controller 38, in high torque (or as is known in the art as "over torque") conditions.
The sensing of torque, in this example, is a function which operates independently of, and concurrently with, other monitoring functions of the controller and implements an override response to over torque conditions to minimize catastrophic pump damage or seizing of the pump.
However, as an embodiment of the exemplified protocol is the operation of the pump at a lower speed setting than would otherwise occur if the pump were operated to maximize gross production over time, the likelihood of an over torque condition occurring is greatly reduced.

100671 Thus, as will be described, the exemplified protocol provides for a threshold pump efficiency value, above which the pump speed is increased toward a maximum pump speed setting and below which the pump speed is decreased toward a minimum pump speed. In some cases, the threshold pump efficiency value may take into account a minimum pump efficiency plus an additional operational variance factor, such as 10 percent, to increase the sensitivity of the controller 38 to negative changes in pump efficiency and thus increase the likelihood that the decreasing of the pump speed occurs before pump efficiency falls to or below the acceptable minimum pump efficiency. Since pump wear, when pumping fluid carrying abrasives, may be directly correlated to pump speed, decreasing pump speed sooner when pump efficiency is falling is believed to help minimize pump damage. With the use of the operational variance factor, increases in pump speed may not occur immediately after minimum pump efficiency is reached, thus allowing for changes in operating conditions such as sudden variations in sand, water or gas volumes being carried in the fluid being produced by the pump to stabilize or pass before increasing pump speed. The appearance of these conditions may dramatically change pump efficiency within the sampling time interval. Such conditions are often characteristic of situations giving rise to over torque, pump off or a dramatic drop in pump efficiency.

100681 With these operating principles in inind, reference may be made to figures 2 and 3a to 3c showing representations of an exemplified operation of the pump monitoring and control protocol carried ('NR-MP[/C'Di .34 out by the controller 38. At step 100, the user sets the controller to manual mode and then, at step 102, configures the controller 38 for a particular well site 12 by entering, directly or indirectly, the following data via the GUI 46.

OPERATOR INPUT:

- MAXIMUM PUMP SPEED
- MINIMUM PUMP SPEED

- MAXIMUM TORQUE ALLOWED
- MINIMUM PUMP EFFICIENCY

- OPERATIONAL VARIANCE FACTOR
SAMPLING TIME INTERVAL

PUMP SPEED INCREASE/DECREASE INCREMENT

PUMP SIZE in M3/Day @ 100 RPM = MANUFACTURER'S PUMP RATING VALUE
HYDRAULICS BYPASS SLOWDOWN TIME INTERVAL

100691 The MAXIMUM PUMP SPEED, in one example, is set to the manufacturer's rated maximum pump speed for a selected pump, while the MINIMUM PUMP SPEED is selected to maintain a minimum recovery flow of oil bearing fluid from the geological formation in order to preserve and continuously grow the network of channels and wormholes therein. The HYDRAULICS BYPASS
SLOWDOWN TIME INTERVAL is smaller than the SAMPLING TIME INTERVAL and is provided to make pump speed adjustments more rapidly or frequently due to the increased potential of pump lock up and/or damage when over torque conditions occur. One or more of these input settings may be provided either in a dedicated data field in an input screen or be provided in a drop down menu format. For instance, the GUI 46 may provide a drop down menu of pump types and manufactures to provide automatically the value for PUMP SIZE in M3/Day a, 100 RPM.

100701 It will be noted that, in this example, the controller 38 stores one PUMP SPEED
INCREASE/DECREASE INCREMENT value. However, the system may be configured to store more CNR-MPIE/CI)A 35 than one increment value for different phases in the operation of the controller 38. For instance, a larger increment value may be provided for a PUMP SPEED DECREASE INCREMENT value, and a relatively smaller increment value may be provided for a PUMP SPEED INCREASE INCREMENT
value, or vice versa.

100711 It will also be noted that the OPERATIONAL VARIANCE FACTOR may be preselected and inputted into the controller 38 as part of the algorithmic programming of controller 38. Hereafter, the term PUMP EFFICIENCY THRESHOLD shall refer to the MINIMUM PUMP EFFICIENCY plus the OPERATIONAL VARIANCE FACTOR. If desired, the minimum pump efficiency may be used as the pump efficiency threshold in the absence of an operational variance factor.

100721 The following is a listing of the operator inputs for an exemplified well site 12:
- MAXIMUM PUMP SPEED: 150 RPM

- MINIMUM PUMP SPEED : 30 RPM, - MAXIMUM TORQUE ALLOWED: 2500 PSI

- MINIMUM PUMP EFFICIENCY : 40 PERCENT

- OPERATIONAL VARIANCE FACTOR: 110 PERCENT
- SAMPLING TIME INTERVAL: 1 HOUR

- PUMP SPEED INCREASE/DECREASE INCREMENT: 5 RPM
- PUMP SIZE in M3/Day @ 100 RPM: 15m3/day @ 100 RPM

- BYPASS SLOWDOWN TIME INTERVAL: 15 MINUTES
PUMP START UP:

100731 Thus, at step 104, the operator turns on the pump to a selected startup pump speed, for example 50 RPM.

100741 There are a number of diagnostic checks that are carried out in the manual mode, which may be done manually by the field operator, or in an automated fashion, or be a combination of both. For instance, if the well site 12 is already being managed by a control and management system such as SCADA, then a number of number of diagnostic checks may be done on a range of conditions such as operating temperatures of different components of the pump and drive train, the condition of the hydraulic pump and drive motor, all with the aim of verifying that the startup conditions of the pump and drive train are normal. Alternatively, the controller 38 may carry out selected diagnostic functions independent of the SCADA management system, in which case the initial diagnostic functions may in some instances include an initial torque sensing function as described below.

100751 When the manual mode steps are complete, the operator then, at step 105, switches the pump 20 to the automatic mode, which proceeds to steps 106, 108 and 1 10, in which the controller 38 begins a continuous monitoring of pump speed, checks the tank level sensor for a baseline measurement and initiates the time count for the first sampling time interval. While steps 106, 108, 110 are shown to occur simultaneously, the steps may also be executed, in some cases, consecutively according to a specific programming sequence in the controller 38. The controller 38 advances then to step 112 at the end of the first sampling time interval and then to step 114 where the controller 38 samples tank level.

100761 The controller advances to step 1 16 to determine if the change in tank level is positive. If NO, the controller initiates a time count, at step 118, for a next sampling time interval. If YES, the controller calculates, at step 120, pump efficiency PE according to the formula above. A "NO" condition would occur if the tank 28 has been emptied or partially drained in order to transport fluid produced from well site 12 to a cleaning plant for processing.

100771 At step 120 the controller 38 calculates the measured pump efficiency by:

= First, calculating the volume of fluid produced during the sampling time interval based on the change in tank level from the beginning of the sampling time interval to the end of such interval and grossing this up to a volume fluid produced over 24 hours;

= Second, noting the pump speed that the pump was operating at during the sampling time interval; and C NR-MP[/CDA 37 = Third, comparing the calculated grossed up volume of fluid produced during such interval as a ratio over the pump speed noted for such interval, against the pump manufacturer's rated volume of fluid produced over the rated pump speed and expressing the calculated grossed up volume of fluid produced during such interval as a ratio over the RPM noted for such interval as a percentage of the pump manufacturer's rated volume of fluid produced over the rated pump speed.

100781 At step 122, the controller 38 compares the calculated pump efficiency against the preset PUMP EFFICIENCY THRESHOLD value. If the calculated pump efficiency is NOT LESS
than the preset PUMP EFFICIENCY THRESHOLD value, the controller 38 advances to step 124 and to determine if the measured pump speed is matches the preset MAXIMUM PUMP SPEED value. If NO, the controller advances to step 126 and increases the pump speed by the PUMP SPEED
INCREASE/DECREASE
INCREMENT value. The controller 38 then advances to step 1 18 to initiate the time count for the next sampling time interval.

100791 Referring once again to step 124, if the calculated pump efficiency is found to match the preset MAXIMUM PUMP SPEED value, the controller 38 advances directly to step 118 to initiate the time count for the next sampling time interval.

100801 Referring once again to step 122, if the calculated pump efficiency is LESS than the preset PUMP EFFICIENCY THRESHOLD value, the controller 38 advances to step 128 to determine if the calculated pump efficiency is LESS than the preset MINIMUM PUMP EFFICIENCY
value. If NO, the controller advances to step 130 to determine if the measured pump speed is equal to the preset MINIMUM PUMP SPEED value. If NO, the controller advances to step 131 to decrease the pump speed by the PUMP SPEED INCREASE/DECREASE INCREMENT value. The controller then advances to step 118 to initiate the next sampling time interval.

CNR-MP[/CDA 38 10081 On the other hand, if, at step 128 the calculated pump efficiency is indeed LESS than the preset MINIMUM PUMP EFFICIENCY value, the controller proceeds to step 132 to determine if, for the immediately previous sampling time interval, the calculated pump efficiency was also LESS than the preset MINIMUM PUMP EFFICIENCY value. If NO, then the controller advances to step 118 to initiate the time count for the next sampling time interval. If YES, the controller proceeds to step 134 to implement a roll back of the pump speed to the preset MINIMUM PUMP SPEED value and then, at step 136, issues an ALARM. The roll back at step 123 is not, in one example, an incremented decrease but rather an immediate slow down response, to permit the system to slow down to the MINIMUM
PUMP SPEED
value. Other slowdown procedures may also be implemented in this step, as desired.

100821 Referring once again to the SET AUTO MODE step 105, this action also initiates a continuous torque monitoring subroutine beginning with step 140 in which the controller collects signals from the torque sensor and, at step 142, compares the a measured torque value against the preset MAXIMUM TORQUE ALLOWED value. If the measured torque exceeds the preset value, an overtorque condition is present and the controller 38 proceeds to steps 144, 146 and 148 at the same time. While steps 144, 146 and 148 are shown to occur simultaneously, the steps may also be executed, in some cases, consecutively according to a specific programming sequence in the controller 38. At step 144, the controller issues an ALARM and an OVERRIDE of the other parallel active subroutines along the various paths following the END TIME INTERVAL STEP 112. At step 148, the controller determines if the measured pump speed is equal to the preset MINIMUM PUMP SPEED value. If NO, the controller advances to step 152 to decrease the pump speed by the PUMP SPEED
INCREASE/DECREASE
INCREMENT value. If YES, the controller advances to step 154 to maintain pump speed. At step 146, the controller initiates a bypass time count for the duration of the preset BYPASS
SLOWDOWN TIME
INTERVAL value, the end of which is marked at step 150. The controller then advances to step 140 to monitor torque and repeats the foregoing sequence.

100831 Alternatively, at step 148, the controller determines if the measured pump speed is equal to zero. If NO, the controller advances to step 152 to decrease the pump speed by the PUMP SPEED

(. NR-MPE/C'I)A 39 INCREASE/DECREASE INCREMENT value. If YES, the controller advances to step 154 to maintain pump speed at zero. In this case, the duration of this zero condition may be relatively short, and terminate when relatively swift remedial action is taken to rectify the overtorque condition. This may involve personnel in a control room receiving the alarm signal issued at step 144 and reverting the system to a manual condition for further remedial action, to remove sand from the pump, such as by flushing or the like. This condition provides the benefit of shutting down the pump temporarily before it becomes damaged and is meant to avoid long term shutdown and repair procedures.

100841 Thus, in one example, at the end of the first hour of operation (step 112), the controller 38 checks the tank level sensor reading (step 114), and using this reading calculates the volume of production that has flowed into the tank over that hour, and using the result of that calculation, calculate the pump efficiency (step 120) as a percentage of the "ideal" efficiency (which is based on the manufacturer's design efficiency for the pump).

100851 In the exemplified protocol of the controller 38, the maximum pump efficiency calculated is given an additional safety factor, in one example 10 percent, though additional operational factor values may be used as desired. In the exemplified protocol of the controller 38, if the calculated efficiency is an amount which is equal to or greater than 10% above the minimum pump efficiency set by the operator (step 122) (example: if the preset minimum efficiency is 40% and the calculated efficiency at the end of the first hour must be 50% or better), the controller increases the speed of the pump (step 126) by the amount of RPM increment previously set by the operator (example 5 RPM) after determining that the pump speed is not yet equal to the preset maximum pump speed.

100861 If the calculated efficiency is an amount which is less than 10% above the minimum pump efficiency set by the operator, the controller 38 reduces the speed of the pump 20 (step 131) by the amount of RPM increment previously set by the operator.

100871 At the end of the second hour of operation and at the end of every hour thereafter the controller 38 repeats the process set out above.

100881 Thus, at the end of each sampling time interval, as long as the calculated efficiency determined at the end of such hour is an amount which is equal to or greater than 10% above the minimum pump efficiency set by the operator, the controller 38 increases the speed of the pump by the amount of RPM increment previously set by the operator, even if the calculated efficiency at the end of a sampling time interval is less than, greater than or equal to the pump efficiency calculated the immediately previous hour.

100891 Provided however, if at the end of any hour the calculated efficiency is an amount which is less than the minimum pump efficiency set by the operator (step 128), the controller quickly rolls back the pump speed to the preset minimum pump speed (step 134) and then issue an alarm (step 136).

100901 In other words, in an example, the controller keeps increasing the speed of the pump each hour (step 126) unless/until the calculated pump efficiency is less than 10%
above the minimum pump efficiency set by the operator or the pump reaches its maximum RPM setting.
While other examples may involve other speed control protocols, in this example, the only time periods in which the controller holds the RPM setting constant for any period of time over one hour is when:

- The controller 38 detects that the level of fluid in the tank has fallen to a level which is lower than the previous hour (step 116) (which indicates that the tank was emptied, in which case the controller 38 skips the process for that interval and waits until the end of the next sampling interval comes up to perform an efficiency calculation);

- The controller 38 detects an over torque situation (step 142) in which case it reduces the pump speed continuously in a series of steps down to the minimum RPM setting (or zero RPM setting) if necessary and if it has to reduce speed to the minimum RPM
setting the CNR-MPtr''CDA 41 controller 38 holds the pump 20 at that speed until an operator attends to check on the problem;

- The controller has increased the pump speed to the preset maximum RPM
setting (step 124), in which case it holds at that point unless pump efficiency falls below 10%
above the minimum pump efficiency set by the operator or an over torque condition occurs; or - The controller has reduced pump speed to the minimum RPM setting as a result of measured pump efficiency falling below the preset minimum pump efficiency for two consecutive sampling time intervals, in which case the controller holds the pump at such minimum RPM
setting until pump efficiency increases above the pump efficiency threshold (which is minimum pump efficiency plus the operational variance).

100911 In other exemplary embodiments, it may be desirable, in some examples, not to use an operational variance factor, in which case the protocol employed with controller 38 may require that:

= the pump speed be increased by the preset pump speed increase increment if the measured pump efficiency at the end of the sampling time interval is greater than or equal to the minimum pump efficiency set by the operator, unless the pump is already operating at the preset maximum pump speed, and = the pump speed be decreased to the preset minimum pump speed if the measured pump efficiency at the end of the sampling time interval is less than the minimum pump efficiency set by the operator, unless the pump is already operating at the preset minimum pump speed.

TORQUE OVERRIDE:

100921 In one example, the pump controller 38 continuously monitors the torque and RPM of the pump and if the maximum torque limit is reached (step 142), the controller reduces the RPM of the pump down by the amount of the RPM increase/decrease increment previously set by the operator (eg. 5 rpm) until the high torque situation has fallen below the preset maximum torque limit (NOTE: the controller does not, in this case, reduce RPM below the previously set minimum RPM
setting), though other speed settings may be employed in other cases. Thus, in this example, the controller 38 makes changes to the pump speed at the time intervals specified by the operator in setting the Hydraulics Bypass Slowdown Time. After the torque has fallen below the maximum torque setting, the controller returns the pump to normal automatic operation by initiating the time count procedure at 110, and following through to step 112 and the steps which follow. Torque control, in this example, is configured to dominate and override other functions of the controller 38. However, there may be other examples in which the torque monitoring function is not continuous but rather carried out after preset torque monitoring intervals. In some cases, the torque monitoring functions may not override other functions of the system but instead permit other functions to continue operating but under conditions that preserve minimum operations while minimizing potential damage both to the pump and the geological formation. Thus, as can be seen, the aim of the controller 38 and its protocol as discussed in the exemplified methods above, is to protect the pump from wearing out prematurely and keep it in operation, while minimizing pump shut down or break down.

100931 Thus, the system 10 is believed to provide an improved method of optimizing a oil well in an unconsolidated sand reservoir by maximizing the amount of oil produced over the life of the well by maximizing the amount of oil produced per unit speed of the pump, in this case per unit RPM, as opposed to simply maximizing the volume of fluid produced over a given time interval.
Further, it is believed that efficiency of the pump expressed as actual volume of fluid produced per revolution of the pump is a more precise measure to use in managing the operation of the pump. Volume of production per revolution of the pump, when producing a fluid carrying an abrasive, translates into a useful measure of the stress on the pump components as a result of friction caused by the abrasive. Running the pump faster may result in a greater volume of fluid being produced in a given time interval. However, at higher RPM's, if the volume of fluid produced per revolution of the pump is low, the pump is encountering greater friction and therefore experiencing greater wear. Further, the system 10 is beneficial in reducing the risk of, if not avoiding, damage and potential seizing of the pump during operation, by detecting an over torque situation and promptly slowing the pump down to allow the higher concentration of sand to be moved through and cleared from the pump gently.

100941 While the pump 20 has been described as a progressive cavity pump, other pumps may also be employed including beam pumps and the like.

100951 While the present invention has been described for what are presently considered the preferred embodiments, the invention is not so limited. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A system for the recovery of oil bearing fluid materials from an oil well, comprising (i) a progressive cavity pump;

(ii) a storage tank arranged to receive fluid materials from the pump;

(iii) a drive unit connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed, with the drive unit operable to vary the pump speed;

(iv) a controller;

(v) a tank level sensor in communication with the controller, for sensing the level of fluid in the storage tank, with the tank level sensor configured for dispatching a tank level signal representative of the tank level;

(vi) a speed sensor in communication with the controller for sensing the pump speed, with the speed sensor configured for dispatching a speed signal representative of the pump speed:
(vii) a torque sensor in communication with the controller for sensing the drive torque, with the torque sensor configured for dispatching a torque signal representative of the drive torque;
and (viii) the controller configured for receiving the tank level signal, the speed signal and the torque signal, respectively, from the tank level sensor, the speed sensor and the torque sensor, and for controlling the drive unit to vary the speed of the pump by one or more preset pump speed increment values, the controller configured to calculate a pump efficiency value and to monitor torque for changes in pump efficiency and torque, and to vary the pump speed according to the pump efficiency value and torque, the controller configured to receive into memory:

- a preset manufacturer's pump rating value for the pump;
- a preset minimum pump efficiency value;

- a preset pump speed increment value;

- a preset sampling time interval for collecting data from the tank level and speed sensors;
- a preset maximum torque setting;

- a preset torque override bypass slowdown time interval;
- a preset minimum pump speed; and - a preset maximum pump speed; and at the end of a first preset sampling time interval, the controller further configured:

a) to receive the tank level signal and to determine therewith a first tank level;

b) with the first tank level, to determine a first change in tank level over the first sampling time interval;

c) and, if the tank level change is positive, to calculate a first volume of fluid collected over the first sampling time interval;

d) to receive the speed signal to determine therewith a first pump speed;

e) and, with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, to calculate a first pump efficiency value;

f) to compare the first pump efficiency value with the preset minimum pump efficiency value;

g) and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, to increase the pump speed by the preset pump speed increment value;
h) and if the first pump efficiency value is less than the preset minimum pump efficiency value, to decrease the pump speed by the preset pump speed increment value;

i) and to repeat steps a) through h) at the end of each sampling time interval thereafter;
j) to receive the torque signal from the torque sensor;

k) and if the torque signal exceeds the preset maximum torque setting, to override steps g) and h) and to decrease the speed of the pump by the preset pump speed increment value and, l) to repeat steps j) and k) at the end of each preset torque override bypass slowdown time interval until:

i) the torque sensor registers a torque less than the preset maximum torque setting , thereby returning to step a); or ii) - the pump speed is reduced to zero.

2. A system as defined in claim 1, the pump efficiency value being calculated as the measured pump efficiency expressed as a percentage of a rated pump efficiency.

3. A system as defined in claim 2, the controller configured to add an operational variance factor to the preset minimum pump efficiency value, the controller further configured to reduce the pump speed by the preset pump speed increment value where, at the end of any preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, and the controller further configured to reduce the pump speed to the preset minimum pump speed where, at the end of each of at least two consecutive preset sampling time intervals, the calculated pump efficiency value is less than the preset minimum pump efficiency value.

4. A system as defined in claim 2, the controller configured to add an operational variance factor to the preset minimum pump efficiency value, the controller further configured to make no change to the pump speed where at the end of any preset sampling time interval the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, and the controller further configured to reduce the pump speed to the preset minimum pump speed where, at the end of each of two consecutive preset sampling time intervals, the calculated pump efficiency value is less than the preset minimum pump efficiency value.

5. A system as defined in claim 1, the drive unit including a drive motor, with the drive motor including an internal combustion engine, an electrical drive motor, and/or an hydraulic drive motor.

6. A system as defined in claim 2, wherein the first pump efficiency value is calculated according to the formula: PE = [(Vt / St)/(Vr/Sr)]100, where:

- Vt is a volume of fluid collected in the tank in a predetermined sampling time interval, adjusted to a 24 hour period;

St is a pump speed during the predetermined sampling time interval, expressed in RPM;

Sr is a manufacturer's rated pump speed, expressed in RPM required to produce Vr; and Vr is a manufacturer's rating for a volume of fluid produced in a rated time interval adjusted to a 24 hour period.

7. A system as defined in claim 6, where the predetermined sampling time interval is one hour.

8. A system as defined in claim 6, the preset torque override bypass slowdown time interval being a fraction of the preset sampling time interval.

9. A system as defined in claim 8, the fraction being one quarter to one half.

10. A system as defined in claim 6, the preset speed increment value being 5 RPM.

11. A system as defined in claim 6, where the pump is driven by hydraulic fluid in a supply line from an external hydraulic pump, the preset maximum torque setting corresponding to an hydraulic pressure in the supply line ranging from about 2500 psi to 2900 psi.

12. A system as defined in claim 6, where the pump is driven by an electric drive motor, the preset maximum load setting ranging from about 35 to 45 amps, corresponding to an amperage drawn by the electric motor to drive the pump.

13. A system as defined in claim 6, the preset minimum pump efficiency value ranging from 25 percent to 80 percent.

14. A system as defined in claim 1, the preset maximum pump speed being set according to a rated maximum pump speed.

15. A system as defined in claim 1, the present minimum pump speed being set to maintain a minimum recovery flow of fluid from the well.

16. A system as defined in claim 1, the controller configured so that the controller does not increase pump speed beyond the preset maximum pump speed and does not reduce the pump speed below the preset minimum pump speed.

17. An oil field control installation, comprising a plurality of oil wells, each being independently controlled by the system of claim 1.

18. A computer-implemented method of controlling an oil well, comprising:

a. providing a progressive cavity pump in a well bore of the oil well;
b. providing a storage tank to receive fluid materials from the pump;

c. providing a pump drive section connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed;

d. configuring the pump drive section to receive instructions to vary the pump speed by one or more preset pump speed increment values;

e. receiving signals from a tank level sensor and a speed sensor indicative of tank level and pump speed respectively;

f. receiving signals from a torque sensor indicative of the drive torque;

g. monitoring a pump efficiency value for changes in pump efficiency and to vary the pump speed according to the pump efficiency value, including:

1. receiving into memory:

a. a preset manufacturer's pump rating value for the pump;
b. a preset minimum pump efficiency value;

c. a preset pump speed increment value;

d. a preset sampling time interval for collecting data from the tank level and speed sensors;

e. a preset maximum torque setting;

f. a preset torque override bypass slowdown time interval;
g. a preset minimum pump speed; and h. a preset maximum pump speed; and 11. after a first preset sampling time interval:

a. receiving the tank level signal and determining therewith a first tank level;

b. with the first tank level, determining a first change in tank level over the first preset sampling time interval;

c. with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

d. receiving the speed signal to determine therewith a first pump speed;
e. with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

f. comparing the first pump efficiency value with the preset minimum pump efficiency value:

g. and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, increasing the pump speed by the preset pump speed increment value;

h. and if the first pump efficiency value is less than the preset minimum pump efficiency value, decreasing the pump speed toward the preset minimum pump speed; and i. and to repeat steps a) through h) at the end of each sampling time interval thereafter;

j. and if the torque sensor registers a torque exceeding the preset maximum torque setting, to override other functions of the control system to decrease the speed of the pump by the preset pump speed increment value;

k. to repeat step j) at the end of each preset torque override bypass slowdown time interval until:

i) the torque sensor registers a torque less than the preset maximum torque setting and then return to step a); or ii) the pump speed is reduced to zero.

19. A method as defined in claim 18, wherein the second instance of step h) includes decreasing the pump speed by the preset pump speed increment value.

20. A method as defined in claim 19, further comprising, in section 1, receiving into memory:

i. a preset minimum pump efficiency value and an operational variance factor, and further comprising, in section II after step k:

1. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, decreasing the pump speed by the preset pump speed increment value; and m. if, at the end of a first preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value, making no change to the pump speed; and n. if, at the end of a second consecutive preset sampling time interval, the calculated pump efficiency value is still less than the preset minimum pump efficiency value, reducing the pump speed to the preset minimum pump speed.

21. A method as defined in claim 19, further comprising, in section 1, receiving into memory:

i. preset minimum pump efficiency value and an operational variance factor, and further comprising, in section 11 after step k:

1. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor, but greater than the preset minimum pump efficiency value, making no change to the pump speed;
and m. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value reducing the pump speed to the preset minimum pump speed.

22. A method as defined in claim 19, further comprising, in section 1, receiving into memory:
i. an operational variance factor, and further comprising, in section II after step k:

1. if, at the end of a preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value plus the operational variance factor but greater than the preset minimum pump efficiency value, making no change to the pump speed;
and m. if, at the end of a first preset sampling time interval, the calculated pump efficiency value is less than the preset minimum pump efficiency value making no change to the pump speed; and n. if, at the end of a second consecutive preset sampling time interval, the calculated pump efficiency value is still less than the preset minimum pump efficiency value, reducing the pump speed to the preset minimum pump speed.

23. A computer-implemented method of controlling an oil well, comprising:

a. providing a progressive cavity pump in a well bore of the oil well;
b. providing a storage tank to receive fluid materials from the pump;

c. providing a pump drive section connected to the pump for delivering a drive torque to drive the pump at a corresponding pump speed;

d. configuring the pump drive section to receive instructions to increase speed by one or more preset pump speed increment values;

e. receiving signals from a tank level sensor and a speed sensor indicative of tank level and pump speed respectively;

f. receiving signals from a torque sensor indicative of the drive torque;

g monitoring a pump efficiency value for changes in pump efficiency and to vary the pump speed according to the pump efficiency value, including:

I. receiving into memory:

a. a preset manufacturer's pump rating value for the pump;
b. a preset minimum pump efficiency value;

c. a preset pump speed increment value;

d. a preset sampling time interval for collecting data from the tank level and speed sensors;

e. a preset maximum torque setting;

f. a preset torque override bypass slowdown time interval;
g. a preset minimum pump speed; and h. a preset maximum pump speed;

II. and, after a first preset sampling time interval:

a. receiving the tank level signal and determining therewith a first tank level;

b. with the first tank, level, determining a first change in tank level over the first preset sampling time interval;

c. with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

d. receiving the speed signal to determine therewith a first pump speed;
e. with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

f. comparing the first pump efficiency value with the preset minimum pump efficiency value;

g. and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, increasing the pump speed by the preset pump speed increment value;

h. and if the first pump efficiency value is less than the preset minimum pump efficiency value, decreasing the pump speed toward the preset minimum pump speed; and i. and to repeat steps; a) through h) at the end of each sampling time interval thereafter;

j. and, if the torque sensor registers a torque exceeding the preset maximum torque setting, to override other functions of the control system to decrease the speed of the pump to zero or to the preset minimum pump speed and to maintain the pump at zero or at the preset minimum pump speed until the torque sensor registers a torque less than the preset maximum torque setting.

24. A computer-implemented method of controlling an oil well, comprising:

- receiving into memory:

- a preset minimum pump efficiency value;
- a preset pump speed increment value;

- a preset sampling time interval for collecting data from a tank level sensor indicative of a level of oil fluid in a tank downstream from an oil pump in the oil well, and data from a speed sensor indicative of a pump speed of the pump;

- a preset maximum torque setting for torque to be delivered to the pump;
- a preset minimum pump speed;

- a preset maximum pump speed; and - a preset manufacturer's pump rating value for the pump;
and after a first operational time period:

- receiving a tank level signal from the tank level sensor and determining therewith a first tank level;

- with the first tank level, determining a first change in tank level over the first preset sampling time interval;

- with the first change in tank level, calculating a first volume of fluid collected over the first preset sampling time interval;

- receiving a speed signal from the speed sensor to determine therewith a first pump speed, - with the first pump speed, the first volume, and the preset manufacturer's pump rating value for the pump, calculating a first pump efficiency value;

- comparing the first pump efficiency value with the preset minimum pump efficiency value;

- and if the first pump efficiency value is equal to or greater than the preset minimum pump efficiency value, signaling an increase in the pump speed by the preset pump speed increment value;

- and if the first pump efficiency value is less than the preset minimum pump efficiency value, signaling a decrease in the pump speed toward the preset minimum pump speed; and - collecting data from a torque sensor indicative of torque being delivered to the pump, and if the torque sensor registers a torque exceeding the preset maximum torque setting, overriding the controller and signaling a decrease in the speed of the pump to zero or to the preset minimum pump speed.

25. A computer readable medium comprising computer-executable instructions for performing the method of claim 24.

26. A system for the recovery of oil bearing fluid materials from an oil well, comprising a pump, a storage tank arranged to receive fluid materials from the pump, a drive unit connected to the pump for delivering a drive torque thereto to operate the pump at a corresponding operating speed, a controller for controlling the drive unit and receiving signals from sensors, a tank level sensor for sensing the level of fluid in the storage tank, the tank level sensor in communication with the controller for dispatching a tank level signal representative of the tank level, a speed sensor for sensing the operating speed of the pump, the speed sensor in communication with the controller for dispatching a speed signal representative of the operating speed, and a torque sensor for sensing the drive torque, the torque sensor in communication with the controller for dispatching a torque signal representative of the drive torque, the controller configured to calculate, at regular time intervals:

- a volume of fluid collected during a regular time interval, according to changes in the tank level;

- a pump efficiency value according to the volume of fluid collected and the speed of the pump, and - a pump efficiency ratio value according to the pump efficiency value and a rated pump efficiency value for the pump;

and, after calculating the pump efficiency ratio, the controller further configured to:

- increase the operating speed from a current operating speed toward a predetermined maximum operating speed, so long as the pump efficiency ratio equals or exceeds a preset minimum pump efficiency ratio value; or - decrease the operating speed from the current operating speed toward a predetermined minimum operating speed, so long as the pump efficiency ratio does not exceed the preset minimum pump efficiency ratio value; and - the controller configured to receive the torque signal and to determine a torque level for the pump, and if the torque level indicates that the pump is in an overtorque condition, the controller configured to override other operations of the controller and to decrease the speed of the pump from a current operating speed to zero regardless of a previously calculated pump efficiency ratio value.