Subterranean solids fallback protection device

Abstract

A subterranean solids fallback protection device (160) has a differential pressure measurement system configured to determine the quantity of solids accumulated within the device based on the pressure differential across the device during operation. A first pressure gauge (170) is positioned above the solids fallback protection device, and a second pressure gauge (170) positioned below the solids fallback protection device, and the differential pressure measurement system includes these gauges for measuring pressure above and below the device.

Description

BACKGROUND TO THE INVENTION

[0001] Specialised downhole pumps are used in the hydrocarbon exploration and production industry in various applications, and in particular for the production of hydrocarbons to surface from significant wellbore depths. There are several types of downhole pump in use, including Electrical Submersible Pumps (ESPs) and Sucker Rod Pumps (SRPs). An ESP is typically located at the bottom of the production tubing, and comprises a downhole electric motor powered and controlled from surface by a power cable which connects to the wellhead. ESPs are highly efficient pumps capable of high production rates.

[0002] An SRP system is powered by a rod extending from surface to the downhole pump, and the stroking action, can be achieved by a “nodding donkey” reciprocating machine, or long stroke hydraulically powered machines. The SRP is also referred to as a reciprocating pump. The downhole pump typically comprises a standing valve and a traveling valve. The standing valve is attached to the tubing. The traveling valve reciprocates with the rod string. Both valves typically comprise a ball check arrangement.

[0003] Downhole pumps are sensitive to sands and other abrasive solids being present in the production fluid. The amount of sand which is produced from a well depends on characteristics of the formation, and various methods are used to control sand production. However, it is common for some amount of sand or abrasive solids to be present in the production fluid. ESPs are particularly sensitive to sand presence due to the nature of their internal components.

[0004] With many production systems which use a downhole pump, problems can arise when the pump is shut down after a period of pumping fluid up the production tubing to surface.

[0005] With an ESP, gravity acting on the column of fluid above the pump (which could be several thousand metres) causes the sand and any other solids to fall back towards the pump with the fluid column inside the tubing. On pump shutdown, the fluid above the pump flows down the tubing and into the well until the fluid levels in the production bore and the annuluses equalise. Due to the complex configuration of the interior features of the pump, there is no direct path for the sand to pass through the pump. And therefore, it tends to settle on top of the pump or in the top portion of the pump. This can cause the pump to become plugged- or can cause internal components to erode.

[0006] When production operations are resumed, a higher load is required to start the pump and push the plug of sand up from the pump. In some cases, this can cause motor burn out in an ESP, a broken shaft, or component erosion over time. Such failure of the downhole pump requires a work-over involving pull-out and reinstallation of the completion. This is an expensive and time-consuming operation.

[0007] When production ceases with an SRP the fluid column is sustained in the tubing by the stationary valve. The entrained solids in the production tubing will fall with gravity in the static fluid column. The falling sand can accumulate several feet on top of the traveling and stationary valve resulting in erosion and valve blockage.

[0008] In some cases, a subterranean solids fallback protection device is installed above an ESP such as a filter and storage device, a check valve, or a diverter valve. The screens in some currently available solids fallback protection devices foul resulting in more solids remaining in the device with each storage and cleanout event. As the immovable solid level inside the device increases the pressure drag across the device will increase. If the device is full of solids, then the ESP cannot be treated with chemicals. Prior art discusses a single gauge which measures pump discharge pressure. Further prior art also presents gauges to measure pressure drop across filters in non-subterranean applications. Current technology does not offer a method to quantify the amount of solids in a subterranean solids fallback protection device and thus indicate when the device requires replacement.

[0009] Similarly, a solids fallback protection device can be installed integrally to the rod string above an SRP system. Prior art details a device with multiple chambers with slits intended to capture the falling solids and which also allow fluid to remove solids upon restart of the SRP system.

[0010] It is amongst the aims and objects of the invention to provide various methods to prevent the above-described deficiencies of downhole pump systems.

[0011] Further aims and objects will become apparent from reading the following description.SUMMARY OF THE INVENTION

[0012] This disclosure is directed at a method to measure the pressure above and below a solids protection device to quantify the amount of solids which cannot be removed.

[0013] As solids build up in the device the pressure drag created by moving fluid will increase. By measuring the pressure above and below, or the differential pressure planned maintenance can intervene resulting in reduced operating cost.

[0014] This disclosure is also directed to systems and methods which will remove solids from fluids and remove solids from the functioning surfaces reducing or eliminating one or more of the problems above with SRP systems. A device with multiple chambers each containing multiple bases with slots and storage volumes will prevent solids from entering a pump and self-clean upon reversing fluid direction in applications involving an sucker rod pump.

[0015] The device measures the amount of solids contained in a subterranean solids fallback protection device by reporting the differential pressure across the device. Preferably, two separate gauges above and below the solids fallback protection device. The device protects an SRP system from suspended solids in the fluid column by containing and storing these solids before they settle on the SRP system by utilizing a multitude of slotted bases in each storage chamber; it also self-cleans these solids upon restarting of the SRP system, and provides a continuous fluid communication path through the device.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] There will now be described, by way of example only, embodiments of the invention with respect to the following drawings,

[0017] FIG. 1 is a diagram illustrating a typical ESP system in a well

[0018] FIG. 2 is a diagram illustrating an ESP system with gauges above and below a solids fallback protection device

[0019] FIG. 3 is a diagram illustrating a typical SRP system

[0020] FIG. 4 is a diagram of an SRP system with a solids fallback protection device installed

[0021] FIG. 5 is a diagram of a solids fallback protection device with select components in separate three dimensional views

[0022] FIG. 6 are cross sectional isometric views of a solids fallback protection device demonstrating the solids capture function

[0023] FIG. 7 are cross sectional isometric views of a solids fallback protection device demonstrating the self-cleaning functionDETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] One or more embodiments of the invention are described below. It should be noted that these and any other embodiments described below are exemplary and are intended to be illustrative of the invention rather than limiting.

[0025] As described herein, various embodiments of the invention comprise systems and methods to measure the immovable storage capacity of solids in a solids fallback protection device and exclude solids from entering an SRP.

[0026] As mentioned above, solids can enter a downhole pump from the discharge, or settle on top of the pump. A method to measure the stored volume of solids will reduce operating costs. A method to capture, contain and self-clean will also reduce operating costs with SRP systems.

[0027] Referring to FIGS. 1 and 2, there is shown a typical ESP system in a subterranean well. The downhole ESP system 120 consists of an electric motor 121, seal section 122, and multistage centrifugal pump 123 installed above the well perforations 140. Power cable 112 conveys power provided by the variable speed drive 110. The power cable 112 connects to the motor 121. The motor rotates the seal section 122 and multistage centrifugal pump 123. The pump 123 pushes the fluid up the production tubing 130. FIG. 2 illustrates the addition of a solids fallback protection device 160 located between the ESP and surface, as well as pressure gauges 170 above and below the solids fallback protection device 160. A further alternative embodiment would communicate the hydraulic pressure from above and below the device to a pressure gauge contained in the ESP system.

[0028] Referring to FIGS. 3 and 4, there is shown a typical SRP system. The main components of the downhole SRP system 220 are a traveling valve 226 and a stationary valve 224 located above the well perforations 222. A beam pump 210 on the surface provides a reciprocating linear motion to the rod shaft string 230 which lifts and lowers the traveling valve 226. FIG. 4 illustrates the addition of a solids fallback protection device 250 located between the downhole SRP system 220 and the surface. An alternative embodiment would have one gauge measure differential pressure above and below the device.

[0029] Referring to FIG. 5, is shown an isometric view of a solids fallback storage device with the housing 550, production tubing 580, and well casing 500 sectioned. The rod string 510 connects to the head 520 and base 590. Rods 530 connect the head 520 to the storage chamber 505, the storage chambers 505 to each other, and to the base 590. Each storage chamber consists of a deflector 540, a storage tube 560, and a multitude of bases 570. The head 520 and base 590 adapt the rod string to the housing 550. The housing 550 transfers the rod string 510 compression and tensile load and contains the captured solids. The head 520 and base 590 have openings which allow fluid and solids to pass. View 5.2 shows a three-dimensional depiction of the deflector 540. View 5.3 shows a three-dimensional depiction of the storage base 570 with a multitude of communication slots 575.

[0030] Referring to FIG. 6, are shown cross sectional isometric views of a solids fallback storage device demonstrating the solid fallback capture function. When the downhole pump ceases to move fluid the fluid column inside the tubing 680 becomes static. Suspended solids 605 begin to fall with gravity. View 6.1 shows a partially full top chamber 610. Solids 605 fall with gravity inside the tubing entering the device through openings in the head 620 as well as between the housing 650 outer diameter and tubing. The solids 605 inside the device accumulate on top of the deflector 640 until the solids 605 fall around the outer surface of the deflector 640. These falling solids 605 then accumulate above the base 670 in the annular volume between the storage tube 660 outer diameter and the housing 650 inner diameter. View 6.2 shows a full top chamber 610 and partially full lower chamber 615. The top chamber has been sectioned. When the top chamber 610 reaches full storage capacity then the falling solids 605 enter the storage tube 660 inner diameter falling to the deflector 640 in the lower chamber 615. The process outlined in view 6.1 with the upper chamber 610 repeats itself with the lower chamber 615. View 6.3 shows a three dimensional depiction of the deflector 640. The deflector 640 directs solids to the annular space between the storage tube 660 and housing 650. Semi-circular voids around the perimeter facilitate solids 605 movement. View 6.4 shows a three-dimensional depiction of the base 670 with slots 675 on the perimeter. View 6.5 magnifies the solids 605 capture function in the top chamber 610. The slots 675 in each sequential base 670 are not aligned to prevent solids 605 from traveling below the bottom base 670. Solids 605 are shown filling the slots 675 in the top base 670. The solids 605 also spread out on the middle base 670 but do not enter the slots 675 in the middle nor lower base 670.

[0031] Referring to FIG. 7, are shown isometric cross-sectional views of the self-cleaning function of a the solids fallback protection device. When the downhole pump begins operating well fluid 710 moves in and around the solids fallback protection device carrying stored solids 705 to the surface. View 7.1 shows the well fluid 710 traveling around the device and entering the device through openings in the base 790. The well fluid 710 continues moving inside the housing 750 and around the bases 770, storage tube 760 and deflector 740. The well fluid 710 carrying solids 705 exits the device through openings in the head 720. View 7.2 shows the fluid 710 entering the bottom base 770 through a slot then traveling perpendicularly to the middle base 770 slot. Once again the fluid 710 travels perpendicularly to the top base 770 slot. A section of the storage tube 760 demonstrates the fluid traveling inside and outside the storage tube 760.

Examples

Embodiment Construction

[0024]One or more embodiments of the invention are described below. It should be noted that these and any other embodiments described below are exemplary and are intended to be illustrative of the invention rather than limiting.

[0025]As described herein, various embodiments of the invention comprise systems and methods to measure the immovable storage capacity of solids in a solids fallback protection device and exclude solids from entering an SRP.

[0026]As mentioned above, solids can enter a downhole pump from the discharge, or settle on top of the pump. A method to measure the stored volume of solids will reduce operating costs. A method to capture, contain and self-clean will also reduce operating costs with SRP systems.

[0027]Referring to FIGS. 1 and 2, there is shown a typical ESP system in a subterranean well. The downhole ESP system 120 consists of an electric motor 121, seal section 122, and multistage centrifugal pump 123 installed above the well perforations 140. Power cable...

BACKGROUND TO THE INVENTION

[0001] Specialised downhole pumps are used in the hydrocarbon exploration and production industry in various applications, and in particular for the production of hydrocarbons to surface from significant wellbore depths. There are several types of downhole pump in use, including Electrical Submersible Pumps (ESPs) and Sucker Rod Pumps (SRPs). An ESP is typically located at the bottom of the production tubing, and comprises a downhole electric motor powered and controlled from surface by a power cable which connects to the wellhead. ESPs are highly efficient pumps capable of high production rates.

[0002] An SRP system is powered by a rod extending from surface to the downhole pump, and the stroking action, can be achieved by a “nodding donkey” reciprocating machine, or long stroke hydraulically powered machines. The SRP is also referred to as a reciprocating pump. The downhole pump typically comprises a standing valve and a traveling valve. The standing valve is attached to the tubing. The traveling valve reciprocates with the rod string. Both valves typically comprise a ball check arrangement.

[0003] Downhole pumps are sensitive to sands and other abrasive solids being present in the production fluid. The amount of sand which is produced from a well depends on characteristics of the formation, and various methods are used to control sand production. However, it is common for some amount of sand or abrasive solids to be present in the production fluid. ESPs are particularly sensitive to sand presence due to the nature of their internal components.

[0004] With many production systems which use a downhole pump, problems can arise when the pump is shut down after a period of pumping fluid up the production tubing to surface.

[0005] With an ESP, gravity acting on the column of fluid above the pump (which could be several thousand metres) causes the sand and any other solids to fall back towards the pump with the fluid column inside the tubing. On pump shutdown, the fluid above the pump flows down the tubing and into the well until the fluid levels in the production bore and the annuluses equalise. Due to the complex configuration of the interior features of the pump, there is no direct path for the sand to pass through the pump. And therefore, it tends to settle on top of the pump or in the top portion of the pump. This can cause the pump to become plugged- or can cause internal components to erode.

[0006] When production operations are resumed, a higher load is required to start the pump and push the plug of sand up from the pump. In some cases, this can cause motor burn out in an ESP, a broken shaft, or component erosion over time. Such failure of the downhole pump requires a work-over involving pull-out and reinstallation of the completion. This is an expensive and time-consuming operation.

[0007] When production ceases with an SRP the fluid column is sustained in the tubing by the stationary valve. The entrained solids in the production tubing will fall with gravity in the static fluid column. The falling sand can accumulate several feet on top of the traveling and stationary valve resulting in erosion and valve blockage.

[0008] In some cases, a subterranean solids fallback protection device is installed above an ESP such as a filter and storage device, a check valve, or a diverter valve. The screens in some currently available solids fallback protection devices foul resulting in more solids remaining in the device with each storage and cleanout event. As the immovable solid level inside the device increases the pressure drag across the device will increase. If the device is full of solids, then the ESP cannot be treated with chemicals. Prior art discusses a single gauge which measures pump discharge pressure. Further prior art also presents gauges to measure pressure drop across filters in non-subterranean applications. Current technology does not offer a method to quantify the amount of solids in a subterranean solids fallback protection device and thus indicate when the device requires replacement.

[0009] Similarly, a solids fallback protection device can be installed integrally to the rod string above an SRP system. Prior art details a device with multiple chambers with slits intended to capture the falling solids and which also allow fluid to remove solids upon restart of the SRP system.

[0010] It is amongst the aims and objects of the invention to provide various methods to prevent the above-described deficiencies of downhole pump systems.

[0011] Further aims and objects will become apparent from reading the following description.SUMMARY OF THE INVENTION

[0012] This disclosure is directed at a method to measure the pressure above and below a solids protection device to quantify the amount of solids which cannot be removed.

[0013] As solids build up in the device the pressure drag created by moving fluid will increase. By measuring the pressure above and below, or the differential pressure planned maintenance can intervene resulting in reduced operating cost.

[0014] This disclosure is also directed to systems and methods which will remove solids from fluids and remove solids from the functioning surfaces reducing or eliminating one or more of the problems above with SRP systems. A device with multiple chambers each containing multiple bases with slots and storage volumes will prevent solids from entering a pump and self-clean upon reversing fluid direction in applications involving an sucker rod pump.

[0015] The device measures the amount of solids contained in a subterranean solids fallback protection device by reporting the differential pressure across the device. Preferably, two separate gauges above and below the solids fallback protection device. The device protects an SRP system from suspended solids in the fluid column by containing and storing these solids before they settle on the SRP system by utilizing a multitude of slotted bases in each storage chamber; it also self-cleans these solids upon restarting of the SRP system, and provides a continuous fluid communication path through the device.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] There will now be described, by way of example only, embodiments of the invention with respect to the following drawings,

[0017] FIG. 1 is a diagram illustrating a typical ESP system in a well

[0018] FIG. 2 is a diagram illustrating an ESP system with gauges above and below a solids fallback protection device

[0019] FIG. 3 is a diagram illustrating a typical SRP system

[0020] FIG. 4 is a diagram of an SRP system with a solids fallback protection device installed

[0021] FIG. 5 is a diagram of a solids fallback protection device with select components in separate three dimensional views

[0022] FIG. 6 are cross sectional isometric views of a solids fallback protection device demonstrating the solids capture function

[0023] FIG. 7 are cross sectional isometric views of a solids fallback protection device demonstrating the self-cleaning functionDETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] One or more embodiments of the invention are described below. It should be noted that these and any other embodiments described below are exemplary and are intended to be illustrative of the invention rather than limiting.

[0025] As described herein, various embodiments of the invention comprise systems and methods to measure the immovable storage capacity of solids in a solids fallback protection device and exclude solids from entering an SRP.

[0026] As mentioned above, solids can enter a downhole pump from the discharge, or settle on top of the pump. A method to measure the stored volume of solids will reduce operating costs. A method to capture, contain and self-clean will also reduce operating costs with SRP systems.

[0027] Referring to FIGS. 1 and 2, there is shown a typical ESP system in a subterranean well. The downhole ESP system 120 consists of an electric motor 121, seal section 122, and multistage centrifugal pump 123 installed above the well perforations 140. Power cable 112 conveys power provided by the variable speed drive 110. The power cable 112 connects to the motor 121. The motor rotates the seal section 122 and multistage centrifugal pump 123. The pump 123 pushes the fluid up the production tubing 130. FIG. 2 illustrates the addition of a solids fallback protection device 160 located between the ESP and surface, as well as pressure gauges 170 above and below the solids fallback protection device 160. A further alternative embodiment would communicate the hydraulic pressure from above and below the device to a pressure gauge contained in the ESP system.

[0028] Referring to FIGS. 3 and 4, there is shown a typical SRP system. The main components of the downhole SRP system 220 are a traveling valve 226 and a stationary valve 224 located above the well perforations 222. A beam pump 210 on the surface provides a reciprocating linear motion to the rod shaft string 230 which lifts and lowers the traveling valve 226. FIG. 4 illustrates the addition of a solids fallback protection device 250 located between the downhole SRP system 220 and the surface. An alternative embodiment would have one gauge measure differential pressure above and below the device.

[0029] Referring to FIG. 5, is shown an isometric view of a solids fallback storage device with the housing 550, production tubing 580, and well casing 500 sectioned. The rod string 510 connects to the head 520 and base 590. Rods 530 connect the head 520 to the storage chamber 505, the storage chambers 505 to each other, and to the base 590. Each storage chamber consists of a deflector 540, a storage tube 560, and a multitude of bases 570. The head 520 and base 590 adapt the rod string to the housing 550. The housing 550 transfers the rod string 510 compression and tensile load and contains the captured solids. The head 520 and base 590 have openings which allow fluid and solids to pass. View 5.2 shows a three-dimensional depiction of the deflector 540. View 5.3 shows a three-dimensional depiction of the storage base 570 with a multitude of communication slots 575.

[0030] Referring to FIG. 6, are shown cross sectional isometric views of a solids fallback storage device demonstrating the solid fallback capture function. When the downhole pump ceases to move fluid the fluid column inside the tubing 680 becomes static. Suspended solids 605 begin to fall with gravity. View 6.1 shows a partially full top chamber 610. Solids 605 fall with gravity inside the tubing entering the device through openings in the head 620 as well as between the housing 650 outer diameter and tubing. The solids 605 inside the device accumulate on top of the deflector 640 until the solids 605 fall around the outer surface of the deflector 640. These falling solids 605 then accumulate above the base 670 in the annular volume between the storage tube 660 outer diameter and the housing 650 inner diameter. View 6.2 shows a full top chamber 610 and partially full lower chamber 615. The top chamber has been sectioned. When the top chamber 610 reaches full storage capacity then the falling solids 605 enter the storage tube 660 inner diameter falling to the deflector 640 in the lower chamber 615. The process outlined in view 6.1 with the upper chamber 610 repeats itself with the lower chamber 615. View 6.3 shows a three dimensional depiction of the deflector 640. The deflector 640 directs solids to the annular space between the storage tube 660 and housing 650. Semi-circular voids around the perimeter facilitate solids 605 movement. View 6.4 shows a three-dimensional depiction of the base 670 with slots 675 on the perimeter. View 6.5 magnifies the solids 605 capture function in the top chamber 610. The slots 675 in each sequential base 670 are not aligned to prevent solids 605 from traveling below the bottom base 670. Solids 605 are shown filling the slots 675 in the top base 670. The solids 605 also spread out on the middle base 670 but do not enter the slots 675 in the middle nor lower base 670.

[0031] Referring to FIG. 7, are shown isometric cross-sectional views of the self-cleaning function of a the solids fallback protection device. When the downhole pump begins operating well fluid 710 moves in and around the solids fallback protection device carrying stored solids 705 to the surface. View 7.1 shows the well fluid 710 traveling around the device and entering the device through openings in the base 790. The well fluid 710 continues moving inside the housing 750 and around the bases 770, storage tube 760 and deflector 740. The well fluid 710 carrying solids 705 exits the device through openings in the head 720. View 7.2 shows the fluid 710 entering the bottom base 770 through a slot then traveling perpendicularly to the middle base 770 slot. Once again the fluid 710 travels perpendicularly to the top base 770 slot. A section of the storage tube 760 demonstrates the fluid traveling inside and outside the storage tube 760.

Examples

Embodiment Construction

[0024]One or more embodiments of the invention are described below. It should be noted that these and any other embodiments described below are exemplary and are intended to be illustrative of the invention rather than limiting.

[0025]As described herein, various embodiments of the invention comprise systems and methods to measure the immovable storage capacity of solids in a solids fallback protection device and exclude solids from entering an SRP.

[0026]As mentioned above, solids can enter a downhole pump from the discharge, or settle on top of the pump. A method to measure the stored volume of solids will reduce operating costs. A method to capture, contain and self-clean will also reduce operating costs with SRP systems.

[0027]Referring to FIGS. 1 and 2, there is shown a typical ESP system in a subterranean well. The downhole ESP system 120 consists of an electric motor 121, seal section 122, and multistage centrifugal pump 123 installed above the well perforations 140. Power cable...

Claims

1. A subterranean solids fallback protection device comprising:a differential pressure measurement system configured to determine a quantity of solids accumulated within the device based on a pressure differential across the device during operation.

2. The solids fallback protection device according to claim 1 further comprising:a first pressure gauge positioned above the solids fallback protection device; anda second pressure gauge positioned below the solids fallback protection device, wherein the differential pressure measurement system includes these first and second gauges for measuring pressure above and below the solids fallback protection device.

3. The solids fallback protection device according to claim 1 for protecting a Sucker Rod Pump (SRP) system from suspended solids in a fluid column, comprising:a housing defining one or more storage chambers;a plurality of slotted bases within each storage chamber, configured to capture and store solids before they settle on the SRP system.

4. The solids fallback protection device according to claim 3, further comprising:a self-cleaning mechanism integrated within the storage chambers, configured to expel stored solids upon restarting of the SRP system.

5. The solids fallback protection device according to 4claim 3, wherein the housing includes continuous fluid communication paths between the storage chambers and external fluid flow, facilitating the movement of fluid and solids through the device.

6. A solids fallback protection device for use in a downhole pump system, comprising:a housinga rod string for connecting the device to a downhole pump system;at least one storage chamber, having a head at a top of the storage chamber and a base at a bottom of the storage chamber, the head and base being connected to the rod string, the head and base each having slots or openings to allow fluid to pass through them.

7. The solids fallback protection device according to claim 6 wherein multiple bases are provided within the at least one storage chamber, the bases being configured with slots which are not vertically aligned.

8. The solids fallback protection device according to claim 6, wherein the rod string is configured to reciprocate in response to a pumping action of a sucker rod pump (SRP) system, wherein the reciprocating movement of the rod string aids in dislodging accumulated solids within the at least one storage chamber during operation of the SRP system9. The solids fallback protection device according to claim 6, further comprising two separate pressure gauges positioned respectively above and below the storage chamber within the housing, wherein the pressure gauges are configured to measure and report a differential pressure across the device.

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