Gas well having water disposal pump

Abstract

A gas well includes a well casing forming a cavity and a gas inlet in fluid communication with the cavity. A pump is disposed in the cavity and includes a pump chamber having an inlet in fluid communication with the cavity and an outlet in fluid isolation with the cavity. The pump further includes a plunger reciprocally moveable along upstroke and downstroke paths. At least a portion of the plunger is positioned and is reciprocally moveable within the chamber between the inlet and outlet during at least a portion of the upstroke and downstroke paths.

Description

FIELD OF THE INVENTION

This invention relates to a gas well and in particular to a gas well having a water disposal pump.

BACKGROUND

Gas wells are commonly used to extract methane and natural gas from subterranean earth formations. One problem encountered with such wells is that various amounts of water may be produced along with the gas. If carried to the surface, the water is disposed of for example by creating ponds and the like. However, due to environmental concerns, the water is often carried away by tank trucks or pipelines and thereafter treated. Alternatively, the water is re-injected back into the ground with a separate or integrated water disposal system. In either scenario, disposal of the water can be expensive.

SUMMARY

In one aspect, a gas well includes a well casing forming a cavity and a gas inlet in fluid communication with the cavity. A pump is disposed in the cavity and includes a pump chamber having an inlet in fluid communication with the cavity and an outlet in fluid isolation with the cavity. The pump further includes a plunger reciprocally moveable along upstroke and downstroke paths. At least a portion of the plunger is positioned and is reciprocally moveable within the pump chamber between the inlet and outlet during at least a portion of the upstroke and downstroke paths. The inlet and outlet are in fluid communication during at least a portion of at least one of the upstroke and downstroke paths.

In one embodiment, the well further includes a production tube having an interior cavity with a water outlet positioned below the gas inlet. The production tube is disposed inside the well casing, with the well casing and production tube defining an exterior cavity therebetween. The pump is disposed inside the production tube. The pump includes an inlet in fluid communication with the exterior cavity and an outlet in fluid communication with the interior cavity. The outlet is positioned above the inlet.

In one embodiment, the pump has a chamber formed between the inlet and outlet. A first one-way valve permits one-way fluid flow into the chamber from the inlet. The pump further includes a plunger moveable within the chamber. The plunger has a top with an outlet in fluid communication with the pump outlet, a bottom and a second one-way valve configured to permit one-way flow of fluid through the plunger from the bottom to the top thereof.

In another aspect, operation of the well includes permitting a flow of gas and water into the exterior cavity from a gas bearing formation. The water in the exterior cavity has a first static head. The operation further includes pumping water in the interior cavity to a second static head, and permitting a flow of said water in the interior cavity through a water outlet to a water disposal strata. In one embodiment, the second static head is positioned above the first static head.

In another embodiment, the pump includes a chamber, a plunger moveably disposed in the chamber and a one-way valve. The chamber has at least one inlet in fluid communication with the cavity and an outlet. The one-way valve is disposed at the outlet so as to allow one-way fluid flow from the chamber through the outlet. The plunger has a top and a bottom and is moveable between at least a lower position and an upper position. The pump chamber inlet is positioned below the bottom of the plunger when the plunger is in the upper position such that the pump chamber inlet is in fluid communication with the chamber. The pump chamber inlet is positioned above the bottom of the plunger when the plunger is in the lower position.

In another aspect, the operation of the well includes permitting a flow of gas and water into the cavity from the gas bearing formation and permitting the water to flow from the cavity into the chamber through the pump chamber inlet when the plunger is in the upper position. The method further includes moving the plunger on a downstroke from the upper position to the lower position and closing the pump chamber inlet as the plunger is moved on the downstroke. The method further includes forcing the water from the chamber through a one-way valve and into a lower formation.

The different aspects and embodiments provide significant advantages over other gas wells. For example, and without limitation, the well automatically disposes of the water present in the gas formation by moving it to the lower water disposal strata rather than bringing it to the surface, whereinafter it must be disposed of, for example by re-injection. The movement of the water is achieved by the simple up and down pumping action of a piston or plunger, which either lifts the water to create a sufficient static head to force the water to the lower strata, or pushes the water downward through a one-way check valve. The operation of any of the embodiments is simple and relatively inexpensive.

The foregoing paragraphs have been provided by way of general introduction, and are not intended to limit the scope of the following claims. The presently preferred embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first embodiment of a gas well having a water disposal pump.

FIG. 2 is an enlarged cross-sectional view of a lower chamber of a pump connected to a production tube.

FIG. 3A-D are top views of various embodiments of the lower chamber shown in FIG. 2.

FIG. 4 is a cross-sectional view of a second embodiment of a gas well having a water disposal pump, with a plunger moving in a downstroke.

FIG. 5 is a cross-sectional view of the gas well shown in FIG. 4 with the plunger moving in an upstroke.

FIG. 6 is a perspective view of pump inlet member.

FIG. 7 is a cross-sectional view of the pump inlet member shown in FIG. 6.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

Referring to FIGS. 1, 4 and 5, various embodiments of a gas well each include a well casing 2 disposed in a bore hole 4. The well casing penetrates the subterranean earth formations, which include a production formation 6, or gas bearing formation that may also include water, and a water disposal formation 8 located below the gas bearing formation, with the production and water disposal formations separated by an isolation formation 10, which is relatively water impermeable. In one embodiment, the well casing is configured as a tube with an interior surface 12 defining a cavity 14. The well casing has at least one, and preferably a plurality of, gas inlets 16, formed for example and without limitation as perforations in the well casing, that are in fluid communication with the production formation 6. The term “plurality” as used herein means more than one. It should be understood that the term “fluid” means a substance capable of flowing, such as a liquid or gas.

A lower portion of the well casing has at least one, and preferably a plurality of, water outlets 18 in fluid communication with the water disposal formation. A bottom of the well casing can be open, as shown in FIG. 1, or closed as shown in FIGS. 4 and 5. The top 20 of the well casing is in fluid communication with a gas outlet 22, which is connected to a collection device (not shown), such as a tank or pipeline.

Referring to FIGS. 1, 4 and 5, a pump 30, 130 is disposed in the cavity 14. The pump 30, 130 includes a pump chamber 32, 132 and a plunger 34, 134 moveably disposed in the chamber. A rod 36, 136 is connected to the plunger and reciprocally moves the plunger 34, 134 within the chamber 32, 132 along an upstroke and a downstroke. A motor (not shown), or other power source, is connected to and moves the rod up and down.

Referring to the embodiment of FIG. 1, a production tube 24 is disposed within the well casing and has an exterior wall 26 defining the cavity 14, referred to with respect to this embodiment as an exterior cavity, between the interior wall 12 of the well casing and the exterior wall 26 of the production tube. It should be understood that the well casing and production tube are preferably circular in cross section, but can be configured in other cross-sectional shapes, including various polygonal shapes. The exterior surface 26 of the production tube extends through and is sealed within a cap 28 secured to the top 20 of the well casing. The exterior surface 26 of the production tube is sealed against the interior surface 12 of the well casing adjacent the bottom of the production tube with a packer 50. In this way, the production tube defines an interior cavity 52 that is in fluid isolation with the exterior cavity 14, meaning fluid cannot flow from the interior cavity to the exterior cavity. In one embodiment, the production tube is formed from a plurality of pieces, including various tubes, pipes and couplers, which can be joined for example and without limitation by threading, welding and the like.

As shown in FIGS. 1-3D, the pump 30 includes a housing 38 defining a lower chamber 40 and an upper chamber 32. As shown in FIGS. 2-3D, the lower chamber 40 is made from a modified seating nipple having a plug 42 positioned in a bottom end thereof. The pump, and in particular, the lower chamber 40, includes a first inlet 44, formed for example by a bushing, in fluid communication between the exterior cavity 14 and the lower chamber 40. At least a portion of the exterior surface 46 of the housing and at least a portion of an interior surface 48 of the production tube are spaced apart to define in part the interior cavity 52, for example a channel portion thereof, and to allow fluid to flow within the cavity from a top to a bottom of the pump. As shown in FIGS. 3A-3D, the channel portion can be defined by forming one or more flat portions 54 formed along a side of the lower chamber housing (shown as one, two, three and four flat portions in FIGS. 3A-3D respectively), which form the channel with the curved interior surface of the production tube.

Referring to FIG. 1, the upper chamber 32 has at least one inlet 56 and at least one outlet 58. The outlet 58, which is positioned above a top of the plunger 34 and adjacent a top of the upper chamber, is in fluid communication with the interior cavity 52. A one-way valve 60 is positioned in or adjacent the inlet 56 so as to permit one-way fluid flow from the lower chamber 40 to the upper chamber 32, or put another way, to permit one-way fluid flow from the exterior cavity 14 to the chamber 32. The plunger 34 has a generally open bottom 62 and defines an interior chamber 64. An outlet 66 is formed in a top portion of the plunger above the generally open bottom. A one-way valve 68 is disposed in the top of the plunger in or adjacent to the outlet 66. The one-way valve 68 permits one-way fluid flow from the plunger chamber 64 through the plunger outlet 66 and through the upper chamber outlet 58 to the interior cavity 52. It should be understood that the inlet 56 to the upper chamber 32 and the outlet 58 from the upper chamber to the interior cavity are in fluid communication when the one-way valve 68 in the plunger is open, even though the one-way valve 60 in the inlet is closed.

In operation, the plunger 34 reciprocally moves between the inlet 56 and outlet 58. On the upstroke, the rod 36 moves the plunger 34 in an upward direction, with the fluid maintaining the one-way valve 68 in the plunger in a closed position. As the plunger moves upward, the top of the plunger pushes fluid in the chamber 32 above the plunger through the outlet 58 of the upper chamber and into the interior cavity 52 with the fluid in the interior cavity being isolated from the fluid in the exterior cavity 14. At the same time, the upward movement of the plunger moves the one-way valve 60 in the upper chamber to an open position, with fluid being drawn into the upper chamber 32 from the lower chamber 40 through the one-way valve 60. It should be understood that the lower chamber could be omitted if the inlet to the upper chamber communicates directly with the exterior cavity. In either case, the pump inlet, for example the upper chamber inlet 56 or the inlet 44, is in fluid communication with the production formation 6, for example by way of the exterior cavity 14, and is positioned below the pump outlet 58, which is in fluid communication with the water disposal formation 8, for example by way of the interior cavity 52.

On the downstroke, the rod 36 moves the plunger 32 in a downward direction, and thereby opens the one-way valve 68 in the plunger so as to allow fluid communication from the inlet 56, from the portion of the upper chamber below the plunger and from the plunger chamber 64, to the portion of the upper chamber above the plunger and the outlet 58. At the same time, the downward motion of the plunger 32 forces the one-way valve 60 in the inlet 56 to a closed position such that fluid in the upper chamber 32 is prevented from flowing into the lower chamber 40.

As the pump 30, and in particular the plunger 32, moves up and down, water is forced into the interior cavity 52 and forms a static head, for example, as it is raised to a level L1 in the interior cavity. As the static head becomes sufficiently high, pressure from the static head forces the water from and through the interior cavity 52 and out of the water outlet 18 in the well casing to the water disposal formation 8. For example, in one embodiment, the static head within the interior cavity is raised above the static head of the production formation water, located at a level L2. Since the interior cavity is isolated from the exterior cavity by way of the packer 50, the water is not allowed to reenter into the exterior cavity or production cavity. The phrase “fluid isolation” as used herein means fluid cannot flow from the pump outlet or water disposal formation to the cavity or gas bearing formation because of the one-way valves.

At the same time, the gas from the production formation rises, or is pumped, from the exterior cavity 14 to the first gas outlet 22 adjacent the top of the well casing. To the extent the pump forces or pumps any gas into the interior cavity 52, the gas rises, or is pumped, from the interior cavity to a second gas outlet 70 adjacent the top of the production tube. The gases from the first and second outlets are collected by one or more collection devices (not shown). It should be understood that in one embodiment, the first and second outlets are in fluid communication.

Now referring to the embodiment of FIGS. 4-7, the pump 130 has one or more inlets 144 in communication with the well casing cavity 14, for example at a location spaced below the production formation 6, or preferably completely submersed in water. The pump inlets 144 are defined, for example, by a fitting 150 having a central, vertical bore 148 shaped and dimensioned to receive the plunger and a plurality of openings or inlets 144 in fluid communication between the cavity 14 and the central bore 148. The pump has an exterior surface 146 that further defines the cavity 14. The pump chamber 132 is positioned below the inlets and has an outlet 158 in fluid communication with the water disposal formation 8 when a valve 160 is open. The well casing outlet 18 is in fluid isolation with the chamber 132 of the pump and the cavity 14, by way of a packer 50 disposed between the interior surface 12 of the well casing and the exterior surface 146 of the pump housing at a location below the inlets. The one-way check valve 160 is disposed in or adjacent to the outlet 158. In one embodiment, the check valve includes a biasing member 162, shown as a compression spring. The check valve 160 permits one-way fluid flow from the pump chamber 132 to the water disposal formation 8. In one embodiment, the fluid flows out of the pump through a lower cavity 164 of the well casing and into the water disposal formation 8.

In operation, the plunger 134 is reciprocally moveable within the chamber 132, and for at least a portion of the movement is moved between the inlet 144 and outlet 158 during both the upstroke and downstroke. During the last portion of the upstroke, the rod 136 pulls the plunger 134, including a bottom thereof, upwardly above the inlets 144 to an upper position, as shown in FIG. 5, such that water can flow into the pump chamber 132. At this time, the inlet 144 of the chamber 132 is in fluid communication with the outlet 158, even though the outlet 158 is closed by way of the spring 162 applying a biasing force against the check valve 160. The valve 160 prevents fluid from being drawn into the pump chamber 132 from the water disposal formation 8 through the outlet 158.

On the downstroke, as shown in FIG. 4, the rod 136 moves the plunger 134 downwardly until the bottom thereof moves past the inlets 144 such that the plunger 134 isolates the inlets 144 from the chamber 132 and thereafter the plunger moves between the inlets 144 and outlet 158. As the plunger continues to move downward, it opens the check valve 160 by pushing fluid against the upward biasing force of the spring 162. The fluid is forced from the chamber 132 through the one-way check valve 160 and into the water disposal formation 8. Meanwhile, the gas rises or is vented, for example by bubbling, or is pumped, from the cavity 14 through an outlet 22 at the top of the well casing to a containment device (not shown).

At the end of the downstroke and the beginning of the upstroke, the bottom of the plunger 134 is in a lower position, and the check valve 160 again closes. In this way, the water in the water disposal formation 8 is in fluid isolation from the water in the cavity 14 and the gas bearing formation 6 by way of the pump 130, and in particular the one-way valve 160. The phrase “fluid isolation” as used herein means fluid cannot flow from the water disposal formation 8 to the chamber 132, cavity 14 or gas bearing formation 6 because of the one-way check valve 160 and packer 50.

In either of the embodiments shown in FIGS. 1, 4 and 5, the well automatically disposes of the waste water by moving it to the lower water disposal strata 8 rather than bringing it to the surface, whereinafter it must be disposed of, for example by re-injection. The movement of the water is achieved by the simple up and down pumping action of the plunger 34, 134, which either lifts the water to create a sufficient static head to force the water to the lower strata as shown in FIG. 1, or pushes the water downward through a one-way check valve 160 as shown in FIGS. 4 and 5. The operation of either of the embodiments is simple and relatively inexpensive.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. As such, it is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is the appended claims, including all equivalents thereof, which are intended to define the scope of the invention.

Claims

1. A gas well having a water disposal pump comprising: a well casing having an interior surface and at least one gas inlet; a production tube having a top, a generally open bottom, an exterior surface and an interior cavity, wherein said production tube is disposed inside said well casing with at least a portion of said exterior surface being spaced from said interior surface of said well casing so as to form an exterior cavity therebetween along an upper portion of said production tube, said production tube having at least one inlet in fluid communication with said exterior cavity, and wherein said exterior cavity is sealed along a lower portion of said production tube below said gas inlet; and a pump disposed inside said production tube, said pump having a chamber with an outlet communicating with said interior chamber of said production tube, and a first one-way valve communicating with said chamber, said first one-way valve configured to permit one-way flow of fluid from said at least one inlet to said chamber, said pump further comprising a plunger moveable within said chamber, said plunger comprising a top with an outlet in fluid communication with said outlet in said chamber, a bottom and a second one-way valve configured to permit one-way flow of fluid from said bottom to said top of said plunger.

2. The gas well of claim 1 wherein said chamber comprises an upper chamber and wherein said pump comprises a lower chamber communicating with said at least one production tube inlet, wherein said first one-way valve is disposed between said lower and upper chambers and is configured to permit one-way flow of fluid from said lower chamber to said upper chamber.

3. The gas well of claim 2 wherein an exterior of at least a portion of said lower chamber is spaced from an interior of said production tube so as to define in part said interior cavity of said production tube and so as to provide fluid communication between said upper chamber outlet and said generally open bottom of said production tube.

4. The gas well of claim 2 wherein said lower chamber is closed at a bottom thereof, wherein said lower chamber is not in direct fluid communication with said interior cavity of said production tube.

5. The gas well of claim 1 further comprising a packer disposed between said lower portion of said production tube and said interior surface of said well casing, said packer sealing said exterior cavity.

6. The gas well of claim 1 wherein said plunger is moveable on a upstroke within said chamber between a lower position and an upper position, and is moveable on a downstroke within said chamber between said upper position and said lower position, wherein said first one-way valve is open and said second one-way valve is closed during said upstroke, and wherein said first one-way valve is closed and said second one-way valve is open during said downstroke.

7. The gas well of claim 1 further comprising a first gas outlet communicating with said exterior cavity and a second gas outlet communicating with said interior cavity.

8. A method of removing gas from a gas bearing formation comprising: providing a well casing and a production tube, said well casing having at least one gas inlet communicating with said gas bearing formation and said production tube having an interior cavity, wherein said production tube is disposed inside said well casing and said well casing and said production tube define an exterior cavity therebetween; permitting a flow of gas and water into said exterior cavity from said gas bearing formation, wherein said water in said exterior cavity has a first static head; pumping water in said interior cavity to a second static head; and permitting a flow of said water in said interior cavity through at least one water outlet to a water disposal strata.

9. The method of claim 8 wherein said pumping said water comprises moving a plunger on a upstroke within a chamber, permitting water to enter said chamber through a first one-way valve on said upstroke and forcing water through an outlet in said chamber with said plunger on said upstroke, moving said plunger on a downstroke within said chamber and permitting water to flow through said plunger through a second one-way valve on said downstroke.

10. The method of claim 8 further comprising removing gas from said exterior chamber through a first gas outlet and removing gas from said interior chamber through a second gas outlet.

11. A gas well having a water disposal pump comprising: a well casing having at least one gas inlet; a production tube having an interior cavity with a water outlet positioned below said at least one gas inlet, wherein said production tube is disposed inside said well casing, said well casing and said production tube defining an exterior cavity therebetween; and a pump disposed inside said production tube, said pump having an inlet in fluid communication with said exterior cavity and an outlet in fluid communication with said interior cavity, wherein said outlet is positioned above said inlet.

12. A gas well having a water disposal pump comprising: a well casing forming a cavity and having at least one gas inlet in fluid communication with said cavity; and a pump having a chamber, a plunger moveably disposed in said chamber and a one-way valve, said chamber having at least one inlet in fluid communication with said cavity and an outlet, wherein said one-way valve is disposed at said outlet so as to allow one-way fluid flow from said chamber through said outlet, and wherein said plunger has a top and a bottom and is moveable between at least a lower position and an upper position, wherein said at least one chamber inlet is positioned below said bottom of said plunger when said plunger is in said upper position such that said chamber inlet is in fluid communication with said chamber, and wherein said at least one chamber inlet is positioned above said bottom of said plunger when said plunger is in said lower position.

13. The gas well of claim 12 wherein said one-way valve includes a biasing member biasing said valve from an open position to a closed position.

14. The gas well of claim 12 further comprising a packer disposed between said well casing and said pump, said packer preventing fluid communication between said cavity and said outlet.

15. The gas well of claim 12 comprising at least one gas outlet in fluid communication with said cavity.

16. A method of removing gas from a gas bearing formation comprising: providing a well casing defining a cavity and having at least one gas inlet and at least one gas outlet in fluid communication with said cavity, and a pump having a chamber and a plunger moveable in said chamber between at least an upper and lower position; permitting a flow of gas and water into said cavity from said gas bearing formation; permitting said water to flow from said cavity into said chamber through a pump inlet when said plunger is in said upper position; moving said plunger on a downstroke from said upper position to said lower position; closing said pump inlet as said plunger is moved on said downstroke; and forcing said water from said chamber through a one-way valve and into a lower formation.

17. The method of claim 16 further comprising preventing water in said lower formation from communicating with said cavity.

18. The method of claim 16 further comprising moving said plunger on said upstroke and simultaneously closing said one-way valve.

19. The method of claim 18 wherein said moving said plunger on said upstroke comprises putting said pump inlet in fluid communication with said chamber and thereby repeating said permitting said water to flow from said cavity into said chamber.

20. The method of claim 18 wherein said closing said one-way valve comprises biasing said one-way valve to a closed position with a biasing member and wherein said forcing said water from said chamber through said one-way valve and into said lower formation comprises opening said one-way valve against a biasing force of said biasing member.

21. A gas well comprising: a well casing forming a cavity and having a gas inlet in fluid communication with said cavity; and a pump disposed in said cavity and comprising a pump chamber and a plunger, said pump chamber having an inlet in fluid communication with said cavity and an outlet in fluid isolation with said cavity, wherein said plunger is reciprocally moveable along upstroke and downstroke paths, wherein at least a portion of said plunger is positioned and is reciprocally moveable within said chamber between said inlet and said outlet during at least a portion of said upstroke and downstroke paths and wherein said inlet and said outlet are in fluid communication during at least a portion of at least one of said upstroke and downstroke paths.

22. A method of extracting gas with a gas well comprising: providing a well casing forming a cavity and having a gas inlet in fluid communication with said cavity; and a pump disposed in said cavity and comprising a pump chamber and a plunger, said pump chamber having an inlet in fluid communication with said cavity and an outlet in fluid isolation with said cavity; reciprocally moving said plunger along upstroke and downstroke paths, wherein at least a portion of said plunger is positioned and is reciprocally moveable within said chamber between said inlet and said outlet during at least a portion of said upstroke and downstroke paths; and moving water through said chamber from said inlet to said outlet with said plunger.