GB2522880A

GB2522880A - Well monitoring method and apparatus

Info

Publication number: GB2522880A
Application number: GB1402106.7A
Authority: GB
Inventors: Magnus Bjellaanes Tvedt
Original assignee: Statoil Petroleum ASA
Current assignee: Equinor Energy AS
Priority date: 2014-02-07
Filing date: 2014-02-07
Publication date: 2015-08-12
Anticipated expiration: 2034-02-07
Also published as: GB2522880B; GB201402106D0

Abstract

A system for conducting measurements and/or interventions in a well includes a plurality of magnetic components for disposition along the well such that their magnetic axes are substantially aligned with the longitudinal direction of the well (fig 4). The system further comprises a conveyor 7 suitable for location within the well and includes at least one magnetic component having its magnetic axis aligned with a travel axis of the conveyor 7, and a position controller for alternating the polarity of either the magnetic components for disposition along the well or the magnetic component(s) of the conveyor 7, such that, in situ, the conveyor 7 is caused to move up or down the well by a required extent. The conveyor 7 may include sensors for collecting data and the data may be transferred between the conveyor 7 and a data transfer unit located in the well.

Description

WELL MONITORING METHOD AND APPARATUS

Technical Field

The present invention relates to a well monitoring method and apparatus. The invention is applicable in particular, though not necessarily, to such a well monitoring method and apparatus that involves rigless and riserless light well intervention but that at the same time does not require conventional wireline intervention.

Background

Production rates from a hydrocarbon well will inevitably decrease with time until the available reserves have been depleted below some threshold level beyond which further recovery is unviable. However, both production rates and total recovery levels can be increased by employing so-called "workover" strategies. These might involve, for example, one or more of the following actions: -Recomplete well with new string of tubing for changed flow velocity and I or pressure loss (heavy intervention); -Plug reservoir zones with poor production (medium intervention); -Remove flow restrictions from wellbore such as sand, scale or debris (medium intervention); -Install artificial lift systems such as gas lift or electric submersible pumps (ESPs) (medium to heavy intervention); -Drill and complete sidetrack to access unproduced sections of a reservoir (drilling activity, not intervention); Additionally, it is important to at least periodically monitor the condition of a well both for safety and production purposes, and to inform decisions regarding appropriate Historically, in the context of subsea wells, both workover and well monitoring required the location of a rig or large vessel above the well, and the installation of a riser between the wellhead and the rig or vessel. Appropriate monitoring and workover tools could be inserted into the well from the rig or vessel, via the riser. Such interventions are however extremely costly, and in order to reduce costs so-called rigless and riserless light well intervention (RLWI) techniques have been developed. These techniques employ, for example, electric-line tools run into a well using a "wireline".

The wireline can be deployed from a relatively light well intervention vessel using dynamic positioning. RLWI techniques reduce the cost barriers to intervention and allow for greatly increased recover rates. RLWI techniques are considered further in "Rigless Intervention: Barriers and Misperceptions About Using Lightweight Intervention Solutions To Increase Oil Recovery from Deepwater, Subsea Wells", Bevan Morrison et al, Offshore Technology Conference, 6-9 May, Houston, Texas, USA, 2013.

Figure 1 illustrates a typical prior art well monitoring scenario with sensors for pressure and temperature fixed at the production packer and at the well head (on platform or seabed). Parameters that are monitored are seal integrity of the Surface Controlled Subsea Safety Valve (SCSSV) -also known as the Downhole Safety Valve (DHSV) -as well as rate, pressures and temperatures in the production bore and in the annulus between the production tubing and production casing. In the context of RLWI, there is an option to do production logging using sensors that are conveyed via wireline from an intervention vessel / rig (subsea) or platform. Analysis of the production flow, e.g. to determine the water content of the flow, hydrocarbon composition (sales value), pressure, temperature, sand content, particles and contaminations, etc, can be performed by routing the flow to a test separator on the production facility as indicated by the upper, upwardly directed arrow.

Despite all of the advantages of known RLWI techniques, they continue to require a significant level of intervention and can provide only very limited data in terms of well history. These are of course disadvantages that are to some extent shared by rig and riser based solutions, and indeed many offshore and onshore (dry tree) well systems.

Summary

It is an object of the present invention to enable well monitoring with a reduced intervention level requirement whilst at the same time allowing for the provision of historical well data.

According to a first aspect of the present invention there is provided a system for conducting measurements and/or interventions in well. The system comprises a plurality of magnetic components for disposition along the well such that their magnetic axes are substantially aligned with the longitudinal direction of the well. The system further comprises a conveyor suitable for location within the well and comprising at least one magnetic component having its magnetic axis aligned with a travel axis of the conveyor, and a position controller for alternating the polarity of either the magnetic components for disposition along the well or the magnetic component(s) of the conveyor, such that, in situ, the conveyor is caused to move up or down the well by a required extent.

Embodiments of the invention need not be constrained by wires within the well, and moreover may avoid the need to interrupt production while collecting measurement data. In the case of offshore wells, the need for heavy and even light intervention rigs and vessels may be avoided or reduced. Embodiments of the invention allow, for example, condition changes to be observed quickly and appropriate intervening actions to be taken.

According to a first aspect of the present invention there is provided a method of conducting measurements and/or interventions in a well. The method comprises operating a magnetic drive means in order to move a conveyor up and down the well and operating sensors and/or intervention tools on the conveyor in order to collect measurement data and/or perform well interventions. The method further comprises transferring data between the conveyor and a data transfer unit located in the well.

According to a third aspect of the present invention there is provided a conveyor suitable for location within a well to conduct measurements and/or interventions. The conveyor comprises at least one magnetic component having its magnetic axis aligned with a travel axis of the conveyor and configured to interact with a plurality of magnetic components disposed along the well such that, in situ, the conveyor can be caused to move up or down the well by a required extent.

Brief Description of the Drawings

Figure 1 illustrates schematically a typical prior art well construction design providing for wireline or coiled tubing interventions; Figure 2 illustrates an RLWI technique according to an embodiment of the present invention; Figure 3 illustrates schematically a conveyor utilised in the technique of Figure 2; Figure 4 illustrates schematically a transport mechanism employed by the conveyor of Figure 3; Figures 5A and 5B illustrate schematically two alternative approaches to implementing the transport mechanism of Figure 4; Figure 6 is a flow diagram further illustrating technique well measurement and monitoring method according to an embodiment of the present invention.

Detailed Description

In order to avoid or at least reduce the need for periodic wireline intervention into a well, and the associated costs in terms of intervention and lost production, and to enable the near continuous monitoring of well conditions, it is proposed here to locate within a well a wireless conveyor that is able to move through the well essentially under its own power. This conveyor is able to accommodate both sensors and light intervention tools, whilst allowing hydrocarbons to flow through it thereby avoiding disruption to production. By moving up and down the production tubing, such a conveyor can collect data relating, for example, to flow performance and well integrity.

This data can be used to continuously update software showing, for example, a well schematic with trend analysis of the well condition.

Although a number of propulsion mechanisms can be used to move the conveyor up and down the well, a magnetic-based propulsion mechanism has particular advantages. In the completion phase of a well, the tubing and reservoir sections are equipped with permanent magnets for propulsion of the conveyor. While the well is producing, the conveyor can move up and down in the well with the aid of built in electromagnetic coils powered by built in batteries or capacitors. The conveyor is charged by an induction field in an upper station of the tubing, with this charging station being connected to a seabed location through a control line on the inside or outside of the tubing, established when the well is completed after drilling or by way of an intervention from rig or vessel in the case of a mature well. Power can be fed down to this subsea location from a surface location, or may be generated at the seabed, e.g. using a subsea generator. The conveyor can operate in any part of the well that has a permanent magnetic field of sufficient strength, such as the upper and lower completion areas, and extending into the reservoir and horizontal sections of a well.

A data transceiver is also provided in the well, at or close to the charging station for exchanging data with the conveyor. This might utilise a wireless transmission mechanism, e.g. using modulation of the charging signals, or might utilise some form of dock which engages the conveyor.

The conveyor contains electronic! software logic that controls a number of parameters and components including movement and position, data storage, and power distribution. While moving in the well, monitored data is collected. Some light processing may be carried out on the collected data within the conveyor, e.g. data compression. When the conveyor reaches the charging station in the top of the well, it uploads and downloads data via the data transceiver.

The conveyor is provided with a passage extending through a central axial region. This passage allows produced hydrocarbons, e.g. oil or gas, to pass through the conveyor.

To help prevent the conveyor from getting stuck in the well, possibly giving rise to data losses and an interruption to production, the logic within the conveyor may be configured to evaluate potential hazards in the well and cause the conveyor to take appropriate avoidance actions.

By installing additional equipment in the centre of the conveyor (open flow area), the conveyor can be used to perform light and intermediate intervention work, take additional advanced measurements, and take samples. Equipment can be installed into the conveyor using, for example, a lubricator located on top of the production tree.

Indeed, the conveyor can be configured to accept tools from a variety of different vendors and service providers, e.g. by conforming to a standardised configuration. The conveyor can also be used to charge additional downhole sensors or up/download data from such sensors.

Figure 2 illustrates the concept of the conveyor in more detail. In the well 1, the casing and production tubing are identified by leference numerals 2 and 3 respectively. The Figure also illustrates an oil production tree 4 and a lubricator (deployment system) 5.

A liner and sand screen 6 extends from the lower end of the production tubing into uncased area of the well. Although the Figure includes certain specific dimensions, these are merely exemplary. The components identified so far are generally conventional.

A conveyor 7 is moveably located within the production tubing 3. The conveyor is described in detail below. A docking station 8 is provided close to the top of the well, directly beneath the oil production tree 4. This is coupled by cable to a power distribution box 9 located on the seabed, close to the well head. The docking station provides a means to charge batteries or capacitors of the conveyor 7, and also to perform calibration and cleaning if required. The conveyor is able to operate over some desired conveyor work area (indicated by the region 18 defined by dotted lines in Figure 2), defined at least by the region of the well over which magnetic drive means are provided.

Figure 3 illustrates the conveyor 7 in more detail. The conveyor comprises a generally annular housing 19 defining a central flow passage 20. The conveyor 7 is equipped with on-board sensors 21 to monitor flow, well integrity, etc. Such sensors may be acoustic, optical, electromagnetic or the like. The flow passage may be configured to accommodate sensors, tools and the like introduced through the lubricator 5. The top of the housing 19 defines a fishing neck 10 to allow conventional wireline fishing tools to be used to retrieve the conveyor, e.g. in the event that the conveyor becomes stuck in the well.

Batteries or capacitors 11 are installed on the conveyor 7, within the housing 19, in order to provide power to the sensors 21, any intervention tools, and the propulsion system (see below). The conveyor 7 is also provided with a charging unit 12, electrically coupled to the batteries or capacitors 11. The charging unit 12 is able to receive energy from the docking station 8 via inductive coupling, when it is located in the docking area of the well, and is able to feed this power to the batteries or capacitors.

The conveyor also comprises a controller 13 including hardware and software entities that are also powered by the batteries or capacitors 11. The controller 13 is coupled to memory and other electronic components (not shown). The controller 13 implements logic to control the movement of the conveyor 7, conduct measurements using the sensors 18, store data and up/download data in the docking area of the well.

With reference again to Figure 3, the conveyor 7 is provided with a sets of electromagnetic coils 14 which have their axes aligned with the central axis of the conveyor 7. To allow the fields generated by the coils to extend radially out into the production tubing, the housing 19 is constructed from plastic or other non-magnetic material. The coils 14 are arrayed both axially along and around the conveyor. The controller 13 is able to switch power to the coils 14 in order to selectively swap the polarities of the coils.

Figure 4 illustrates schematically the installation in the well of permanent magnetics 15 on the outside of the production tubing 3 or in the flow area of the production tubing, e.g. affixed to an inner surface of the production tubing 3. [These magnets are strong enough for their fields to penetrate into the interior space through a metal tubing.

Alternatively, the tubing may be made of a composite material (e.g. plastic and carbon), or the magnets may be located on an inner surface of the tubing.] Each magnet provides north (+) and south (-) poles, and these are aligned along the production tubing so that alternating "+ -+ -" etc poles are ordered in the longitudinal direction. In the example shown, two diametrically opposed strings of permanent magnets 16 are provided along the production tubing. Figure 4 also shows the interaction of the magnetic fields generated by the permanent magnets 15 with the magnetic fields generated by the coils 14 provided on the conveyor 7. It will be appreciated that by switching the polarity of the coils 14 the conveyor 7 can be caused to move stepwise up and down the conveyor due to the interaction between the static and induced magnetic fields. Moreover, by counting the steps, the controller 13 is able to determine the precise position of the conveyor 7 within the well 1. As the coils 14 extend around the conveyor 7, any rotation of the conveyor 7 within the well will not result in a release of the conveyor and its location and movement can still be controlled. The conveyor may be equipped with calliper fingers measuring the inside diameter of the tubing, which may help prevent rotation of the conveyor due to the resulting friction.

Figure 5A further illustrates this transport mechanism, with permanent magnets arranged around or within the production tubing, and electromagnets arranged on the conveyor 7. Figure 5B illustrates an alternative configuration where electromagnets 16 are installed around or within the production tubing 3 and permanent magnets 17 are installed on the conveyor 7. However this approach may be less desirable given that it requires the installation of greater infrastructure within the well including power cables running into the well from the wellhead.

As has already been suggested above, when the conveyor is located within the docking are, it is possible to introduce further specialist sensors or tools into the central passage of the conveyor 7. This may be achieved, for example, via the lubricator.

Alternatively, the conveyor may be retrieved from the well using a wireline, a sensor or tool introduced to the conveyor on the surface, and the conveyor reintroduced to the well.

The approach described here is able to provide the end user with, for example, an overall status indication of the well condition based on pre-set parameters and algorithms available to the end user or implemented on a server. Any change in status may be highlighted and presented graphically to the end user who can read data from the well in more detail as needed. Well integrity measurements such as steel corrosion, threaded coupling leaks, and elastomer wear are critical data that can lead to the shut in of a well if not treated early. Also changes in cement and formation integrity are critical data to gather and present after each run.

Flow restrictions such as scale or sand build up in the well or production tubing deformation can cause reduced production, and sensors that detect such problem areas will report back to the end user with depth and an analysis of the problem Status or data dumps from downhole sensors can be provided through the conveyor's data storage. This includes data such as valve positions, and available downhole hydraulic or electric power. Fluid flow analysis can reveal reservoir zones with high content of unwanted fluids such as gas or water in an oil well, or an evaluation of the total well stream can give data basis for changing the flow regime in the well.

Figure 6 is a flow diagram further illustrating the use of the conveyor in, for example, a hydrocarbon producing or injection well. At step Si the conveyor is moved to a charging location at the top of the well. This process involves operating the coils on the conveyor. At step S2, the batteries in the conveyor are wirelessly charged. Data is also transferred between the conveyor and the data transfer unit located in or close to the well. Once charging and data transfer is completed, the conveyor may be moved up and down the well to perform measurements and collect data (step S3). Figure 6 shows a further step S2a involving the transfer of data from the data transfer unit to some user site, e.g. a central server at the well operators HQ or operations centre. In response to the analysis of this data, control data may be sent in the opposite direction, i.e. to the data transfer unit. This data is then installed in the conveyor when it next returns (or on a subsequent return) to the charging location.

The approaches described above may be employed to provide a number of significant advantages as compared to known approaches. For example, moving from discrete to continuous monitoring of wells enables interventions early in the development stage of a (problem) situation, at which stage the cost of intervention may be lower than at a later stage when the situation may have developed to the point of an incident (affecting well flow performance or integrity). Clearly, the need for intervention vessels is reduced as is the complexity of intervention jobs, e.g. the need for an expensive drilling rig based recompletion may be avoided.

Deployment of the proposed approaches may increase the flexibility of well design as the conveyor can be used to maintain or replace completion components more frequently than cable conveyed interventions.

Fluid samples and other special tests can be carried out by installing specialist tools on the conveyor, e.g. through the lubricator or other deployment system.

It will be appreciated by the person of skill in the art that various modifications may be made to the above described embodiments without departing from the scope of the present invention. For example, whilst the invention has been illustrated above in the context of RLWI, it is also applicable to other well types including, for example onshore or dry tree wells.

Claims

Claims 1. A system for conducting measurements and/or interventions in well and comprising: a plurality of magnetic components for disposition along the well such that their magnetic axes are substantially aligned with the longitudinal direction of the well; a conveyor suitable for location within the well and comprising at least one magnetic component having its magnetic axis aligned with a travel axis of the conveyor; a position controller for alternating the polarity of either the magnetic components for disposition along the well or the magnetic component(s) of the conveyor such that, in situ, the conveyor is caused to move up or down the well by a required extent.
2. A system according to claim 1, wherein the conveyor comprises an electrical energy storage unit and an on-board inductive charger, the system further comprising an inductive charging station for installation in the well such that, in situ, electrical energy can be transferred from the inductive charging station to said electrical energy storage unit via the on-board inductive charger.
3. A system according to claim 2, wherein said inductive charging station is configured for installation in the well at or close to the top of the well.
4. A system according to any one of claims ito 3, wherein each of said plurality of magnetic components for disposition along the well comprises a permanent magnet, and the or each magnetic component of the conveyor is an electromagnet, said position controller being an on-board component of the conveyor for switching the polarity of the electromagnet(s).
5. A system according to any one of the preceding claims, the conveyor comprising one or more sensors, and a sensor controller for controlling the sensor(s) and for processing and storing collected sensor data.
6. A system according to any one of the preceding claims and comprising a first data transfer unit for installation in the well and a second data transfer unit provided on the conveyor such that, in situ, data can be exchanged between the first and second data transfer units.
7. A system according to claim 6, wherein said first and second data transfer units are configured to exchange data wirelessly.
8. A system according to claim 6 or 7 when appended to claim 2, wherein said first data transfer unit is configured for installation in the well in co-location with said inductive charging station.
9. A system according to any one of the preceding claims, wherein said plurality of magnetic components are configured for disposition along a production tubing of the well.
10. A system according to any one of the preceding claims, said conveyor comprising a plurality of magnetic components arranged in an array along and around the conveyor.
11. A system according to any one of the preceding claims, said plurality of magnetic components for disposition along the well being arranged for disposition in two or more longitudinally extending strings.
12. A system according to any one of the preceding claims, wherein said well is one of a hydrocarbon producing well and an injection well.
13. A system according to claim 12, wherein said conveyor comprises a housing defining a central flow through passage such that, in situ, hydrocarbons or injection fluid is able to flow through the conveyor via the passage.
14. A method of conducting measurements and/or interventions in a well and comprising: operating a magnetic drive means in order to move a conveyor up and down the well; operating sensors and/or intervention tools on the conveyor in order to collect measurement data and/or perform well interventions; and transferring data between the conveyor and a data transfer unit located in the well.
15. A method according to claim 14, wherein a plurality of magnetic components are disposed along the well such that their magnetic axes are substantially aligned with the longitudinal direction of the well and the conveyor is provided with at least one magnetic component having its magnetic axis aligned with a travel axis of the conveyor, said step of operating a magnetic drive means in order to move a conveyor up and down the well comprising alternating the polarity of either the magnetic components disposed along the well or of the magnetic component(s) of the conveyor.
16. A method according to claim 14 or 15 and comprising operating the magnetic drive means in order to move the conveyor to a charging location within the well, and operating an inductive charging station at that location in order to charge an on-board energy storage unit of the conveyor.
17. A method according to claim 16, wherein said step of transferring data between the conveyor and a data transfer unit located in the well is carried out when the conveyor is in said charging location.
18. A method according to claim 17 and comprising operating the magnetic drive means in order to move the conveyor to a location within the well where a sensor or other device is fixedly located within the well, transferring electrical energy from said on-board energy storage unit to the sensor or other device and / or transferring data between the conveyor and the sensor or other device.
19. A method according to any one of claims 14 to 18 and comprising operating the magnetic drive means in order to move the conveyor to a location at the top of the well, introducing a further sensor or tool into the well and attaching this to the conveyor, and using the attached sensor or tool to perform measurements or interventions in the well.
20. A method according to any one of claims 14 to 19, wherein said well is one of a hydrocarbon producing well and an injection well.
21. A conveyor suitable for location within a well to conduct measurements and/or interventions, the conveyor comprising: at least one magnetic component having its magnetic axis aligned with a travel axis of the conveyor and configured to interact with a plurality of magnetic components disposed along the well such that, in situ, the conveyor can be caused to move up or down the well by a required extent.
22. A conveyor according to claim 21, wherein said at least one magnetic component is an electromagnetic component having its magnetic axis aligned with a travel axis of the conveyor, the conveyor further comprising: an electrical energy storage unit configured to provide electrical power to the or each electromagnetic component; an on-board inductive charger for receiving electrical energy and for supplying this to the electrical energy storage unit; and a position controller for alternating the polarity the or each electromagnetic component such that, in situ, the conveyor is caused to move up or down the well by a required extent.
23. A conveyor according to claim 21 or 22 and comprising one or more sensors and or one or more intervention tools.
24. A conveyor according to claim 23 and comprising a memory for storing collected data by a sensor.
25. A conveyor according to any one of claims 21 to 24, wherein said conveyor is suitable for location within a hydrocarbon producing well or an injection well.
26. A conveyor according to claim 25 and comprising a housing defining a central flow through passage such that, in situ, hydrocarbons or injection fluid are able to flow through the conveyor via the passage.
27. A conveyor according to claim 26, wherein said housing defines said central flow through passage such that, in situ, the passage may receive a sensor or intervention tool.
28. A conveyor according to any one of claims 21 to 27 and comprising a plurality of magnetic components arrayed along and around the conveyor.
29. A conveyor according to any one of claims 21 to 28, said housing defining a fishing neck to facilitate wireline retrieval of the conveyor from a well.
30. A conveyor according to any one of claims 21 to 29 and comprising an on-board data transfer unit for transferring data in situ between the conveyor and a further data transfer unit located in the well.
31. A conveyor according to claim 30, wherein said on-board data transfer unit is configured to transfer data wirelessly.