RU2310069C2 - System for automatic measuring of volume gas content and real density of drilling fluid - Google Patents

Abstract

FIELD: measuring equipment, particularly for oil production industry, namely for drilling rigs.

SUBSTANCE: system comprises measuring module, pneumatic module and electronic module. Measuring module is made as vertical pipe with upper and lower chambers. Installed in lower chamber of measuring module is selecting device. Differential pressure sensor is installed in vertical pipe. Total pressure sensor and drilling fluid supply level indicator are located in upper chamber. Upper chamber of measuring module is connected with pneumatic module by means of two pneumatic pipes. Pneumatic module includes vacuum pump, electric drive and three pneumatic electrovalves. Measuring and pneumatic modules are connected with electronic module through electric links. Electronic module is adapted to control system operation, as well as to record and transmit information.

EFFECT: increased measurement accuracy and reliability, as well as improved reliability of automatic measurement system operation.

7 cl, 2 dwg

Description

The invention relates to measuring equipment and can be used in the oil and gas industry in drilling rigs to determine the volumetric gas saturation and the true density of the drilling fluid as part of automatic control devices for drilling process parameters and during geological and technological research and gas logging.

To prevent emissions and open fountains, the hydrostatic pressure on the bottom when opening a productive formation by a well should slightly exceed the reservoir pressure. The excess hydrostatic pressure above the reservoir is determined by special regulatory documents, but should be minimal, since excessive overloading of the solution sharply reduces the penetration rate, irreversibly affects the initial filtration properties of the reservoir in the bottomhole formation zone, and provokes spontaneous hydraulic fracturing of the borehole accompanied by catastrophic departure of the solution and ejection with the transition to an open fountain. Therefore, the basis for preventing emissions and removals in the well is careful monitoring of the hydrostatic pressure of the drilling fluid column on the exposed reservoir. In drilling practice, such control is carried out by periodically measuring the density of the drilling fluid exiting the well.

However, unlike incompressible drilling fluids that do not contain a gas phase, the measurement of the density of carbonated drilling fluids does not allow determining the pressure of the drilling fluid at the bottom of the well. This is explained by the fact that the free gas contained in the drilling fluid is compressed in the well under the influence of the pressure of the liquid column and its volume concentration decreases by hundreds of times, while the density of the fluid in the well practically approaches the density of the original non-carbonated drilling fluid.

Based on this, aerated drilling fluid requires two density measurements: the apparent density at the exit from the well, and the true density in the wellbore. Since the apparent density does not give an idea of the pressure in the well, the hydrostatic pressure in the well should be determined by the true density.

The true density of aerated drilling fluid with sufficient accuracy for practice can be determined by the formula (Degtev NI, Zinkevich AI Control and degassing of drilling drilling fluids. - M .: Nedra, 1978, 152 S.):

where ρ _and is the true density of the drilling fluid (without gas);

ρ _g - density of aerated drilling fluid;

V _g - volume concentration of free gas in solution in%.

To restore the density of the solution, it is necessary to degass it, without resorting to its weight. However, in practice, with the slightest decrease in density due to aeration, a weighting agent is introduced into the clay mud, which almost always causes severe consequences due to a significant unreasonable increase in the pressure of the drilling fluid column on the formation.

Even if there are no outbursts and open fountains, the opening of productive formations in overweight solutions will definitely worsen the filtration properties of the reservoir due to the formation of mudding and penetration zones, reducing the production capabilities of the well, and also significantly reduce the technical and economic performance of drilling operations by reducing the speed drilling and the occurrence of various complications.

With a decrease in the density of the drilling fluid (due to the inflow of produced water, the introduction of reagents, the deposition of weighting agents or due to the appearance of free gas in the solution), it is necessary to take operational decisions to increase the weight of the drilling fluid (for the first reasons) or to degass it without weighting (when free gas ) Therefore, it is necessary to quickly determine the concentration of free gas in the solution and its apparent density, after which, using the above formula (1), calculate the true density of the solution. If it meets the norm, you should degass the solution without resorting to its weight.

For the purpose of regular monitoring of the drilling fluid by the free gas content and true density, a method for determining the concentration of free gas in carbonated fluids by the compression method has been developed, manual and automatic devices for regular monitoring have been developed and implemented (Berezhnoy A.I., Degtev N.I. Degassing flushing drilling fluids. - M.: Gostoptekhizdat, 1963, 164 pp .; Degtev NI, Zinkevich AI Control and degassing of drilling drilling fluids. - M .: Nedra, 1978, 152 pp.). Of these sources of information are known: the plunger device VG-1 (SU 147364, publ. 1962, No. 10), VG-2, the upgraded device VM-6 (hand held devices); automatic device for continuous measurement of free gas in drilling mud, automatic AKG devices, automatic complexes AK-1 and AK-2.

A disadvantage of the known hand-held devices is their unsuitability for organizing continuous high-precision control of the drilling fluid according to the content of free gas.

The disadvantages of all known automatic devices for determining the free gas content in the drilling fluid by compression method are:

- discreteness of measurement with a cycle time of 3 minutes (20 measurements per hour);

- small volume of the measured sample (100 cm ³ );

- low measurement accuracy.

These disadvantages are not so significant in the overall control of the drilling fluid, but they do not allow the use of these devices in gas logging. For example, at a drilling speed of the reservoir layer of 60 m / h (which is typical for Western Siberia), one determination will be for 3 m of penetration, which is unacceptable for gas logging.

A device is known for the continuous determination of the volumetric gas saturation of a drilling fluid by installing 3 ^x high-precision pressure sensors on a detachable mouth (Lukyanov E.E., Strelchenko V.V. Geological and technological research of wells. - M.: Oil and gas, 1997, 688 p. ), but, unfortunately, due to the low height of the detachable mouth and the small measuring base, this promising method for determining the volumetric gas saturation of the drilling fluid is far from always possible.

A device for determining the gas content of a drilling fluid according to SU 1481661, 12.01.87, containing inductance-type conductivity (resistance) sensors placed in two measuring chambers under different pressures is known. The disadvantages of this device are the need to use a pump to supply the solution and the low accuracy of determining the gas content. These shortcomings did not allow to introduce the device into the practice of drilling operations.

A device for automatically measuring the volumetric gas content of a drilling fluid according to SU 1492239, 10/14/1987, containing a sampling and measuring chamber. When this device is in operation, sampling for analysis is carried out without using a pump to supply the solution due to the flow of drilling fluid by gravity when the receiver part is submerged under the level in the trench. The disadvantage of this device is the low reliability when working on viscous drilling fluids. The reliable operation of the device is not conducive to the presence of a large number of mechanical elements in it. In addition, a small sample volume and a sufficiently long cycle of its research seriously reduce its informational value.

Closest to the automatic detection system proposed as an invention is a device known according to SU 1046487, 06/22/82, containing a selection device, a compression chamber with pressure and level sensors located in it, according to the readings of which, through a computing unit, volumetric gas content is determined . The device also works without the use of a pump, a sample of drilling fluid flows by gravity into the selection device, and then transferred to the compression chamber. The disadvantages of this device are the difficulty of its functioning at high values of the viscosity of the drilling fluid due to the small pressure drop in the trench and the low accuracy of determining the gas content both at the measurement point and in the entire flow of the drilling fluid due to the small volume of the sample and a long research cycle.

The objective of the invention is to increase the accuracy and reliability when measuring the volumetric gas content and the true density of the drilling fluid, as well as improving the reliability of the system by simplifying the design, increasing the efficiency of technological decisions and automating the measurement process.

The solution to this problem is achieved by the fact that the system for automatically measuring the volumetric gas content and the density of the drilling fluid contains a measuring module, a pneumatic module, an electronics module, while the measuring module is made in the form of a vertically arranged pipe with lower and upper chambers, a selective device is installed in the lower chamber of the module , a differential pressure sensor is placed on a vertical pipe, an absolute pressure sensor and a solution level indicator are installed in the upper chamber a, the upper chamber of the measuring module with two pneumatic tubes is connected to a pneumatic module containing a vacuum pump, an electric motor and three pneumatic solenoid valves, the measuring and pneumatic module are electrically connected to an electronics module that performs the functions of controlling the operation of the system, recording and transmitting information.

The selection device located in the lower chamber of the measuring module consists of a saddle placed on the inlet of the chamber and a locking element located inside the chamber and connected by a rod to the electrovalve, the inlet of the electrovalve through the power connector is connected to the relay of the electronics unit.

The differential pressure sensor is made in the form of a hydrostatic densitometer, the measurement base of the hydrostatic densitometer, determined by the distance between the pressure sampling points, exceeds 1000 mm.

The fluid level switch located in the upper chamber of the measuring module is made in the form of an ultrasonic level switch, which provides an electrical signal to the electronics module when the measuring module is filled with drilling fluid.

The measuring module is equipped with a float switch for drilling fluid level at the sampling point, connected to the power supply connector to the vacuum pump motor and providing automatic switching on and off of the vacuum pump.

The electronics module contains a programmable controller that controls the automatic cyclic operation of the system by turning on and off the solenoid valve in the lower chamber of the measuring module, which ensures the operation of the selective device and the electro-pneumatic valves of the pneumatic module, which establish low, atmospheric and high pressure in the upper chamber of the measuring module.

The electronics module contains a solid-state non-volatile memory for recording cyclically measured and calculated system output parameters: apparent density, volumetric gas content and true density of the drilling fluid and an information transfer interface in parallel with recording in solid-state non-volatile memory with real-time binding via electric communication lines to the driller’s console, to the station of geological and technological research or gas logging station, to the workplace of the drilling foreman, supervisor and to top level drilling management

The presence of these essential features of the device proposed as an invention, allows to achieve the task. To obtain a technical result, a representative sample of the drilling fluid that is sucked into the measuring module by a vacuum pump is subjected to a three-fold density determination using a high-precision hydrostatic densitometer: under vacuum at the final stage of sucking the sample into the measuring module, under atmospheric pressure at the moment of supplying the upper part of the atmospheric pressure measuring module, and under high pressure when pumping air under pressure.

The obtained values of ρ _in when R _in , ρ _and when R _a and ρ _p when R _p used to determine (calculate) the content of free gas (gas saturation) in the drilling fluid according to the expressions:

where V _g is the volumetric content of free gas,%;

ρ _a - density at atmospheric pressure P _a ;

ρ _in - density under vacuum P _in ;

ρ _p - density at high pressure P _p .

The most accurate values of V _g are obtained by the expression (4).

After determination (calculation) values of V _g are computed mud true density ρ _and the expression (1):

where ρ _g is the density of aerated drilling fluid under atmospheric pressure (ρ _a , in expressions (2-3)).

The decompression-compression method for determining the gas saturation of a drilling fluid, implemented by the proposed device, is basically no different from the compression method for determining it, with the only difference being that the density is determined both under overpressure and under vacuum. However, in practical application, suctioning the solution under vacuum gives a huge advantage, because it does not require contact between the drilling fluid and the pump, which dramatically increases the reliability of the system and provides quick emptying of the measuring module when atmospheric pressure is applied to its upper part, and then increased pressure. An advantage is the extended pressure range during measurements (vacuum - increased pressure), which, when using expression (4) to determine V _g, increases the measurement accuracy.

Figure 1 presents a diagram of the proposed as an invention of a system for automatically measuring the volumetric gas content and density of the drilling fluid.

Figure 2 shows a sequence diagram explaining the operation of the system.

The system contains three main modules: measuring module, pneumatic module and electronics module.

The measuring module comprises a measuring pipe 1 with an inner coating of a water-repellent film, for example fluoroplastic. The lower chamber 2 is screwed onto the lower part of the measuring tube 1 with the receiving pipe 3 submerged beneath the level of the drilling fluid, and the upper chamber 4 is screwed to the upper part of the measuring tube, ending with the exhaust pipe 5. On the measuring tube 1, there is a differential pressure sensor 6 made in the form hydrostatic densitometer on a measuring base Δh≥1000 mm On the upper chamber 4 there are loops 7 for hanging the measuring module above the sampling point, an absolute pressure sensor 8, a nozzle 9 for air supply, and an alarm 10 of the upper level of the solution is located inside the chamber 4. On the lower chamber 2, there is a power supply connector 11 of the electrovalve 12 located inside the chamber 2. On the rod 13 there is a locking element 14, which, in the de-energized state of the electrovalve 12, is mounted on the seat 15. On the receiving pipe 3 of the drilling fluid on the bracket 16 there is a float switch 17 of the beginning of circulation .

The pneumatic module contains a vacuum pump 18 with an electric motor 19. The inlet of the vacuum pump 18 through the electro-pneumatic valve 20 and the pneumatic tube 21 is connected to the exhaust pipe 5 of the measuring module, the overpressure output of the vacuum pump 18 through the electro-pneumatic valve 22 and the pneumatic pipe 23 is connected to the fitting 9 of the upper chamber 4 measuring module, on the pneumatic tube 23 there is a tap to the electrovalve 24. The pneumatic module is placed in a sealed enclosure (not shown in the diagram).

The electronics module includes a power supply 25; fee 26 collection and conversion of information; a controller 27 for performing computational operations and controlling the operation of the system; relay 28, through which the inclusion of the solenoid valve 12; a relay 29, which disables the operation of the power of the electric motor 19 of the vacuum pump 18; solid state non-volatile memory 30 with a real-time clock; an interface 31 for transmitting information to a driller’s console, to a gas logging station or a geological and technological research station, to jobs of a drilling foreman, technologist, or supervisor. The electronics module is placed in a sealed thermostatic housing (not shown in the diagram) with electrical I / O and the ability to read information from a solid state non-volatile memory.

A system for automatically measuring the volumetric gas content and density of the drilling fluid works as follows.

The power supply unit 25, operating from a 220 V network, provides the necessary voltage values for the operation of all components of the system.

Using the loops 7, the measuring module is suspended above the sampling point. When the drilling fluid measuring module appears at the installation site of the receiving pipe 3 (when turning on the drilling fluid or squeezing the drilling fluid out of the well while lowering the drilling tool), the float switch 17 starts circulating and supplies voltage to the relay 29, which turns on the electric motor 19 of the vacuum pump 18. At the same time the controller 27 provides power to the solenoid valve 20 and through the relay 28, connector 11, the inclusion of the solenoid valve 12. The vacuum pump 18 through the pneumatic tube 21 and the exhaust pipe 5 pumps the air из from the upper chamber 4 of the measuring module, a vacuum (vacuum) is created, the drilling fluid begins to rise in the measuring pipe 1. The pressure (vacuum) in the measuring module is determined through the absolute pressure sensor 8.

The rise of the solution continues until the upper level switch 10 is triggered, the relay signal from which enters the controller 27, and then, by the command of the controller 27, the electro-pneumatic valve 20 is activated, disconnecting the measuring module from the vacuum pump 18, the electrovalve 12 is de-energized, the rod 13 together with the locking element 14 moves down, providing landing locking element 14 on the saddle 15. When the time t ₁ = c 1 controller 27 outputs a control signal to actuate electropneumatic valve 24 providing access to the top chamber 4 of eritelnogo air module. The pressure in the upper chamber 4 of the measuring module abruptly (in fractions of a second) becomes equal to atmospheric. After a time t ₂ = 1.5 s, at the command of the controller 27, the electro-pneumatic valve 24 is turned off and the electro-pneumatic valve 22 is turned on, providing air through the pneumatic line 23 and nozzle 9 to supply the upper chamber 4 of the measuring module with excess pressure from the outlet nozzle of the vacuum pump 18. Due to a small amount of free space in the measuring module (≤1 l), the pressure in the system quickly reaches the set values set by the program in the controller 27 (from 1800 to 2000 mbar absolute pressure). When the pressure on the absolute pressure sensor 8 is reached, the values established in the controller 27 last for a time t _{3 of} about 1-2 s return the electro-pneumatic valve 22 to its initial state (depressurizing the pressure from the vacuum pump to the atmosphere), after which, while turning on the electro-valve 12, it again switches the electro-pneumatic valve 22 to supply excess pressure to the upper chamber 4 of the measuring module. The drilling fluid located in the measuring module is quickly (in 3-4 s) ejected from the measuring module, in which the pressure drops to values slightly more than atmospheric. Thus triggered electropneumatic valves 20 and 22, providing a vacuum measurement module and the rise of a new representative sample of drilling fluid (V L ≥1,5 _etc.) into the measuring tube 1. After the time T _n cycle of repeated system.

Cyclograms of control signals when turning on and off the valves 12, 24, 20, 22 are illustrated in FIG. 2 by curves, the numbers of which correspond to the digital symbols of the corresponding valves in FIG. The corresponding curve of the cyclic change in absolute pressure versus time P (t) in the measuring module during the operation of the system is also shown here.

Recommended for use in the vacuum pump system, it is possible to create a vacuum of 457 mm Hg (5.9 meters water column), which ensures the rise of the drilling fluid with a density of 2500 kg / m ³ to a height of 2.3 m with a capacity of 18 to 2 l / min (average value 10 l / min) depending on vacuum and lifting height. For the densities of fluids 1150-1350 kg / m ³ commonly used in drilling practice, a sample of 2 liters can be raised to a height of 2 m in about 6-10 s and emptied in about 4-6 s. Thus, the length of the measurement cycle to determine the volumetric gas saturation, density at atmospheric pressure and the true density of the drilling fluid is 15-20 s (180-240 measurements per hour).

The achieved expressness of measurement allows increasing the detail and accuracy of parameter determination in automatic mode by almost an order of magnitude, which will significantly increase the safety and technical and economic performance of drilling operations, and also provides the conditions for the implementation of a new direct quantitative method for exploring wells during drilling - gas logging by volumetric gas saturation of a solution . For example, at a drilling speed of 60 m / h per 1 meter of penetration, 4 measurements will be made (25 cm per measurement), which will allow for the separation of oil and gas-saturated objects even in a thin-layered section.

Expanding the range of operating pressures (from vacuum to excess), a large base for measuring a hydrostatic densitometer, a large volume of a representative sample of drilling fluid, high expressivity of research, precision accuracy of primary information converters, simplicity and reliability of the design of the proposed system provide high accuracy in determining the output parameters in automatic mode for a wide range of drilling fluid densities in all categories of wells.

In order to exclude gas losses in the trenches, it is recommended that the drilling fluid be taken into the system from the annulus before the fluid contacts the atmosphere, in the extreme case, as close as possible to the fluid outlet from the well.

To measure the vacuum (or absolute pressure) in the system (sensor 8), the PMP4000 series universal pressure sensor of increased accuracy is used (Druck pressure sensors. Catalog of Tekknou CJSC, St. Petersburg, 2002, p. 45-46) in the range 0- 2000 mbar absolute pressure, and for measuring differential pressure (density) - a differential pressure sensor of the same series in the range 0-175 mbar. Measurement accuracy of PMP4000 series sensors ± 0.04% VPI, 400% overload, stability during the year ± 0.1% VPI. The use of these sensors in a system on a measuring base Δh = 1000 mm will allow working with drilling fluids in the range of their densities from 750 to 1750 kg / m ³ , providing a determination of volumetric gas saturation, apparent density of carbonated fluids at atmospheric pressure and their true density with an error of not more than ± 0.1 ÷ 0.2%.

A one and a half-time supply of the solution volume above the upper inlet of the densitometer guarantees the correct measurement of the density at atmospheric and elevated pressure, when the carbonated column of the drilling fluid is compressed.

As an upper level signaling device 10 in chamber 4, for example, an ultrasonic level indicator device UZS-107 can be used (Nomenclature catalog of Teplopribor OJSC, Ryazan, 2003, from 53-73)

As a signaling device 17, a reliable float signaling device can be used, for example, a NIVOFLOAT indicator (prospectus from NIVELCO PROCESS CONTROL CO. Budapest, Hungary, 2005) with a maximum load of up to 1.1 kW and degree of protection 1P68.

The results obtained in the proposed system in the form of an express periodic determination of the apparent density of the drilling fluid, volumetric gas saturation of the drilling fluid and the true density of the drilling fluid through the data collection and conversion board 26 are entered into the solid state non-volatile memory 30 with reference to real time with parallel transmission through the interface 31 to the driller’s console, to the station for geological and technological research or a gas logging station, as well as to the workplace of the drilling master, those nologist, supervisor and top level drilling management.

Claims (7)

1. A system for automatically measuring the volumetric gas content and density of the drilling fluid containing a measuring module, a pneumatic module, an electronics module, characterized in that the measuring module is made in the form of a vertically arranged pipe with lower and upper chambers, a selective device is installed in the lower chamber of the module, the vertical pipe contains a differential pressure sensor, an absolute pressure sensor and a signaling device for the solution supply level are installed in the upper chamber, the upper chamber is a meter th module is connected to two pneumatic pipes to a pneumatic unit comprising a vacuum pump, a motor and a three pnevmoelektroklapana, measuring and pneumatic unit are connected in electrical communication with the electronics unit performing operation control functions of the system, recording and transfer of information. 2. The system according to claim 1, characterized in that the selective device located in the lower chamber of the measuring module consists of a saddle placed on the inlet of the chamber and a locking element located inside the chamber and connected via a rod to the electrovalve, the inlet of the electrovalve through the power connector is connected to the relay of the electronics unit. 3. The system according to claim 1, characterized in that the differential pressure sensor is made in the form of a hydrostatic densitometer with a base for measuring a hydrostatic densitometer, determined by the distance between the pressure sampling points Δh≥1000 mm. 4. The system according to claim 1, characterized in that the solution level switch located in the upper chamber of the measuring module is made in the form of an ultrasonic level switch providing an electrical signal to the electronics module when the measuring module is filled with drilling fluid. 5. The system according to claim 1, characterized in that the measuring module is equipped with a float switch for drilling fluid level at the sampling point, connected to a power supply connector to the vacuum pump motor and automatically turning the vacuum pump on and off. 6. The system according to claim 1, characterized in that the electronics module contains a programmable controller that controls the automatic cyclic operation of the system by turning on and off the solenoid valve in the lower chamber of the measuring module, which ensures the operation of the selective device and the electro-pneumatic valves of the pneumatic module, which establish low, atmospheric and high pressure in the upper chamber of the measuring module. 7. The system according to claim 1, characterized in that the electronics module contains a solid-state non-volatile memory for recording cyclically measured and calculated output parameters of the system: apparent density, volumetric gas content and the true density of the drilling fluid and an information transfer interface in parallel with recording in solid-state non-volatile memory with real-time binding via electric communication lines to the driller’s console, to the geological and technological research station or gas logging station, to the workplace about the drilling master, supervisor, and top level drilling management.

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