Retrievable pump systems for wells and methods of use

Abstract

A wellbore pumping system for pumping fluid, the system with a retrievable reciprocating pump selectively disposable in inner tubing (which may be e.g. production tubing or coiled tubing) movable to and from a landing structure of a bottom hole assembly (“BHA”), the BHA connected to another tubular which is an outer tubular, such as production tubing or casing, which encompasses the inner tubing.

Claims

1. A system for pumping production fluid from a wellbore, the wellbore extending from an earth surface down into the earth, the system installable in an inner tubing surrounded by an outer tubular in a wellbore, the outer tubular comprising production tubing or casing, an inner wall of the outer tubular and an outer wall of the inner tubing defining an annulus through which fluid is flowable, the system for pumping production fluid up the annulus and out of the wellbore, the system comprising a pump, the pump comprising a retrievable reciprocating pump selectively disposable in the inner tubing, the pump having a fluid inlet and a power section for receiving power fluid and a power piston movable within the power section, the power piston reciprocable within the power section to provide reciprocal pumping action for pumping the production fluid from the wellbore through the fluid inlet, movement of the power piston drawing production fluid from the wellbore, and a valve connected to the pump, the valve comprising an integral control valve for controlling the pump, the integral control valve able to provide power fluid to the pump to move the power piston to effect reciprocal pumping action, the power section able to receive power fluid from the inner tubing, and the pump having a production section, a first chamber, and a second chamber, the second chamber having a fluid outlet, and a power rod connected to the power piston, a plunger comprising a production fluid plunger connected to the power rod, the power rod for movement within the first chamber and the plunger movable within the second chamber so that downward movement of the plunger in the second chamber expels production fluid from the second chamber out through the fluid outlet into the annulus for pumping to the earth surface.

2. The system of claim 1 further comprising a pump seal structure on an exterior of the pump to seal between the exterior of the pump and an interior of the inner tubing, said pump seal structure comprising a plurality of seals including a first seal structure and a second seal structure, the first seal structure spaced apart from the second seal structure on the exterior of the pump, the first seal structure being sufficiently spaced apart from the second seal structure to insure effective sealing when the first seal structure is adjacent to an opening in the inner tubing while the second seal is not adjacent to said opening.

3. A method for pumping fluid from a wellbore and employing a pumping system as claimed in claim 2, the method comprising: inhibiting pump stalling as the pump passes the opening in the inner tubing.

4. A method for pumping fluid from a wellbore and employing a pumping system as claimed in claim 1, the fluid comprising production fluid, the wellbore extending from an earth surface down into the earth, the method comprising: installing the outer tubular in a wellbore, installing the inner tubing within the outer tubular, installing the pumping system in the inner tubing, and with the pump, pumping production fluid from the wellbore, up the annulus, and out of the wellbore.

5. The method of claim 4 further including the integral control valve providing power fluid to the pump to effect reciprocal pumping action, thus moving the pump to and from a landing structure of a bottom hole assembly connected to the outer tubular.

6. The method of claim 5 further comprising moving the pump down the inner tubing to seat on the landing structure of the bottom hole assembly.

7. The method of claim 6 wherein the bottom hole assembly has an opening, further comprising moving the power piston upward within the pump drawing production fluid from the wellbore, through the opening of the bottom hole assembly, through the fluid inlet of the pump and into the second chamber.

8. The method of claim 4 wherein a receiver is located above the wellbore at a wellhead of the wellbore further comprising pumping the pump up the wellbore into the receiver.

9. The method of claim 8 wherein the wellhead includes an isolation valve, the method further comprising closing the isolation valve with the pump within the receiver so that the receiver is isolated from fluid communication with the wellbore.

10. The method of claim 8 further comprising moving the pump from the receiver into a position within the inner tubing.

11. The method of claim 4 further comprising moving the power rod in the first chamber and moving the plunger in the second chamber to expel production fluid from the second chamber into the annulus.

12. The method of claim 4 further comprising moving the power piston downward to expel return fluid from beneath the power piston and out of the power section into the annulus so that the return fluid combines with pumped production fluid in the annulus.

13. The method of claim 4 wherein the pump is releasably secured in the inner tubing, further comprising pumping fluid down the annulus to free the pump.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) These drawings illustrate various embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or legally equivalent embodiments.

(2) FIG. 1 is a side schematic view of a system according to the present invention with a pump according to the present invention.

(3) FIG. 2 is a crosssection view of part of the system of FIG. 1 showing the pump within the inner tubing and the inner tubing seated on the seating nipple of the bottom hole assembly.

(4) FIG. 2a shows the inner tubing of the system of FIG. 1 and as shown in FIG. 2.

(5) FIG. 2b shows the pump of the system of FIG. 1 and as shown in FIG. 2.

(6) FIG. 3 shows an embodiment of a pump for a system according to the present invention.

(7) FIG. 4 shows a receiver for mounted on a wellhead for receiving a retrievable pump according to this invention.

(8) FIG. 5 shows an embodiment of a pump for a system according to the present invention.

(9) FIG. 6A is a front view of a pump system according to the present invention.

(10) FIG. 6B is a crosssection view along line 6B-6B of FIG. 6A.

(11) The figures are not necessarily to scale.

DETAILED DESCRIPTION OF SOME EMBODIMENTS OF THE INVENTION

(12) FIG. 1 shows a system 10 according to the present invention which has a wellhead 12 at the earth's surface on top of which is a pump receiver 14 for selectively housing a pump 20. The pump 20 is movable down within tubing 18 (e.g. coiled or production) which is an inner tubing and rests on part of a bottom hole assembly 15 which has a one way valve 16a which controls the flow of wellbore fluids to the pump 20. Coiled tubing or production tubing may be used; e.g., known small production tubing. The bottom hole assembly 15 is connected to the tubing 18 (but it can be, optionally, connected to the casing 24 which cases a wellbore 22).

(13) The tubing 18 provides a fluid flow conduit for moving fluid to and from the pump 20. The tubing 18 and the casing 24 define a production fluid annulus 26 between them and the pump 20 pumps production wellbore fluids into the annulus 26 and to the surface. This production fluid annulus 26 can be used to: 1. conduct pumped fluid from the bottom of the annulus to the surface for removing fluid from the wellbore; and 2. conduct pumped fluid from the surface to the bottom hole assembly 15 for the purpose of moving (raising) the pump 20 to the surface within the bore of the coiled tubing 18.

(14) As shown in FIG. 1 and in more detail in FIGS. 2-2b, the bottom hole assembly 15 sits on a seating nipple 16b of the bottom hole assembly 15 so that the tubing/bottom-hole assembly interface is sealed with seals 18a on a nose 18e of the tubing 18. The one-way valve 16a includes a movable ball 16c and a valve seat 16d against which the ball 16c is held when the pump 20 is pumping fluid through a port 18f of the tubing 18 into the production fluid annulus 26. When the pump 20 is pumping production fluid through an opening 16e of the bottom hole assembly 16 into a space 18c within the tubing 18, the ball 16c is moved away from the valve seat 16d so that flow is possible through the opening 16e.

(15) A bottom 20b of the pump 20 seals against a surface 18h of a shoulder 18g of the bottom hole assembly 15. Seals 20t seal a tubing/pump interface. Optionally, the pump 20 includes a control valve, in one aspect this is an integral control valve 22. The pump 20 may have a piston in the chamber 20m connected to the rod 20e or the rod 20e itself may act as a fluid displacer.

(16) The pump 20, in one embodiment as shown in FIG. 3, has a power section 20x and a production section 20y. The power section receives power fluid from the integral control valve 22 during a production fluid pumping operation. A power piston 20d connected to a power rod 20e moves within a chamber 20s, and part of the power rod 20e is movable in a chamber 20m. Downward movement of the rod 20e expels production fluid from the chamber 20m out through a valve 20p and a fluid outlet 20i into an annulus 18p between the pump and the interior surface of the tubing 18 (from this annulus 18p the fluid is pumped to a communication port 18f). Upward movement of the power piston 20d and the rod 20e draws production fluid from the wellbore through a valve 20q, through the opening 16e of the bottom hole assembly, through a fluid inlet 20j of the pump 20 and into the chamber 20m. A seal barrier 20g seals against the rod 20e. The fluid inlet 20j (see FIG. 3) extends into an opening 18k of the bottom hole assembly 15 and seals 20k seal the fluid inlet 20j in place (not shown in FIG. 2). Power fluid above the piston 20d is conducted via lines 22d, and the valve 22, and the line 22c back to a surface pump system PP. The valve 20q closes so that wellbore fluids are pumped out of the outlet 20i; and this valve opens to permit wellbore fluid to flow into the chamber 20m. The check valve 20p prevents wellbore fluids from flowing back into the chamber 20m through the outlet 20i. Fluid is forced into the production fluid annulus 26 only during system downstroke.

(17) The seals 20t (see FIGS. 2, 2b, and 3) separate the higher pressure power fluid from the lower pressure produced fluid during pumping operations; and also separate the higher pressure retrieval fluid from the lower pressure tubing fluid during pump retrieval operation. The differential pressure across the seals 20t maintains pump 20 in seated production position during operation; and also the differential pressure across these seals lifts the pump 20 to surface during a retrieval operation.

(18) In one embodiment, return fluid from the power section is mingled with production fluid during the pumping operation. The power piston moves downward, expelling fluid from beneath the power piston which is referred to as “return fluid”. It is forced out of the power section, through the valve and into the produced fluid annulus. In one design, a one-way valve controls flow of this return fluid.

(19) The integral valve 22 controls power fluid that moves the power piston/rod apparatus within the pump 20 and automatically reciprocates this power apparatus. The valve 22 directs power fluid from a line 22a to a line 22b to move the power apparatus upward, pumping production fluid into the chamber 20m. The valve then directs power fluid from the chamber 20s into a line 22d to move the power apparatus downward, pumping the production fluid from the chamber 20m, through the outlet 20i, into the production fluid annulus 26. The power fluid is pumped by the pump system PP on the surface.

(20) A stroke indicator 20h is a slim diameter rod attached to the power piston which causes the valve to shift when the piston reaches the end of its stroke for each direction.

(21) FIG. 4 shows the pump receiver 14 on top of the wellhead 12. The wellhead 12 includes a shut off valve 12a and flange(s) 12b for mounting the wellhead at a wellbore. The receiver 14 has a housing 14a (also referred to as a “lubricator/catcher”) sized and configured to receive and enclose the pump 20 after the pump 20 has been pumped into the housing 14a. A selectively actuatable latch 14b can maintain the pump 20 within the housing 14a. A removable cover 14c covers and closes off the housing 14a. With the cover 14c removed, the pump 20 can be removed from the housing 14a.

(22) The wellhead 12 may be any suitable known wellhead assembly with suitable known wellhead valves. Among other things, the wellhead 12 includes structures and apparatuses for: catching the pump 20 during a pump retrieval operation; for deploying the pump 20 during pump installation and replacement operations; and for isolating the pump 20 and the housing 14a from the wellbore during pump retrieval and deployment operations. FIG. 5 shows a pump system 21 somewhat like the system shown in FIG. 3. A fluid plunger 21f in a power section has an internal valve apparatus 21z that is a “travelling valve” which includes an inner channel 21n with a valve seat 21o against which can seat a ball 21p to selectively close off the valve apparatus 21z so that fluid flow through the channel 21n is prevented; e.g., when the fluid plunger is being raised. When the plunger 21f is moving downwardly, the ball 21p is unseated from the seat 21o allowing fluid to flow through the channel 21n. Other parts of the system 21 are like parts of the valve 20 and the same numerals as in FIG. 3 indicate like parts. Power section seals 21s are on the exterior of the power section.

(23) With the system 21, production fluids enter the chamber 20m through the valve 21z on the system's upstroke and simultaneously fluid is forced out of the chamber through the outlet 20i to the surface. The valve 22 reverses the stroke and, as the rod 20e moves down, fluid in the chamber 20m is forced through the travelling valve 21z and above the plunger 21f and then out the outlet 20i. In a down stroke, the net volume of fluid expelled from the chamber 20m is the area of the rod times the stroke length.

(24) FIGS. 6A and 6B show a pump 60 according to the present invention releasably disposed within a bore 69c of a receiver 69. A flange 69g of the receiver 69 provides for connection of the receiver 69 to a wellhead (not shown; like the wellheads shown in FIGS. 1 and 4). The receiver 69 has a port 69b for a fluid conduit used during retrieval and deployment of pump so that the pump moves to the very top of the receiver; and a drain port 69c for draining the receiver prior to removing the pump from the receiver, e.g. draining power fluid from the receiver. A connector 69d provides a connection for connecting the receiver to the wellhead. A cap 69a provides access to the bore 69c for removal of the pump 60 and for access to a catch mechanism 69f which includes a movable catch member 69k movable to abut a shoulder 65a of an upper end 65 of the pump 60 to releasably hold the pump 60 within the receiver 69. In one aspect, the movable catch member is a release mechanism with a spring-loaded segmented collet. When the top of the pump encounters the collet, the collet expands over the top of the pump and then holds it.

(25) The pump 60 has a sealing nose 62 for sealingly engaging another surface such as a surface of an opening of a bottom hole assembly (as in FIGS. 1, 2, and 2A). Seals 63 on a body 61 of the pump 60 are below and spaced apart from seals 64 on the body 61. In certain particular aspects, to assist in fluid circulation as the pump is moving into or out of a well, these seals are spaced apart a distance greater than the diameter or the largest dimension of any opening that the pump 60 will pass through when moving in tubing, thus inhibiting stalling of the pump when it passes through such an opening; i.e., no matter where the pump is, at least one set of seals will seal the pump/tubing-interior interface. Fluid passing around a first set of seals will be impeded by the second set of seals which is sufficiently spaced apart from the first set of seals.

(26) The present invention therefore provides a method for pumping fluid from a wellbore, the method including pumping fluid from a wellbore, the fluid comprising a production fluid or combination of production fluids, the pumping effected with a wellbore fluid pumping system as any disclosed herein according to the present invention

(27) The present invention, therefore, provides a wellbore pumping system for pumping fluid, the system including inner tubing, for example coiled tubing or production tubing, a pump within the inner tubing, the pump comprising a retrievable reciprocating pump according to the present invention selectively disposable in the inner tubing. Such a system can have a second tubular such as production tubing or casing which encompasses the inner tubing, a bottom hole assembly connected to the second tubular, a landing structure for the bottom hole assembly, the pump movable to and from the landing structure of the bottom hole assembly. In one such system production fluids from a wellbore are pumpable by the pump into a production fluid annulus defined between the inner tubing and the second tubular for fluid flowing to and from the surface. In one such system the fluid is pumpable from the surface down the production fluid annulus to free the pump so that a freed pump is pumpable to the surface within the inner tubing. In such systems the pump may be deployed from and received back within a receiver on a wellhead at the surface. Such systems may include a power section and a power piston (or rod or fluid displacer) movable therein, and the integral valve controls the pump, and power piston reciprocable within the power section of the pump to provide reciprocal pumping action. Such systems can include a seating nipple at the bottom of the second tubular, e.g., production tubing or casing, and the bottom hole assembly is selectively disposable with the seating nipple. In such systems a bottom hole assembly has one port or a plurality of fluid communication ports which provide for the flow of production fluid pumped by the pump to flow into the production fluid annulus. Using such systems in a pumping operation, the power section can receive power fluid from the inner tubing; and return fluid from the power section can combine with pumped production fluid. In such systems the pump can be retrievable by reversing differential pressure across the pump; e.g., by directing power fluid down the produced fluid annulus and thereby lifting the pump to the surface. In such systems the pump can be pumped up the well and received within a receiver apparatus on top of the wellhead; e.g., a receiver apparatus in communication with the wellhead and having an isolation valve that is closeable once the pump is situated within the receiver apparatus. In such systems the pump can have a power section and a production section; the power section for receiving power fluid, e.g., but not limited to power fluid from an integral control valve during a production fluid pumping operation; a power piston connected to a power rod for movement within a first chamber and a produced fluid plunger (or rod or fluid displacer) connected to the power rod for movement in a second chamber; downward movement of the produced fluid plunger expelling production fluid from the second chamber out through a fluid outlet into an inner annulus between the pump and the interior surface of the inner tubing so that from this inner annulus fluid is pumpable to a communication port. In such systems upward movement of a power piston of the power section can draw production fluid from the wellbore, through an opening of a bottom hole assembly, through a fluid inlet of the pump and into the second chamber. In such systems there may be a seal barrier dividing the first chamber from the second chamber. Any pump in any system herein may have pump seals for separating higher pressure power fluid from lower pressure produced fluid during pumping operations; and/or also for separating higher pressure pump retrieval fluid from the lower pressure tubing fluid during a pump retrieval operation; and/or a differential pressure across the pump seals for maintaining the pump in a seated production position during operation; and/or differential pressure across these seals for lifting the pump to surface during a retrieval operation. In such systems it is possible to provide the mingling of return fluid from a power section with production fluid during a pumping operation when a power piston, rod, or fluid displacer moves downward, expelling fluid from beneath the power piston, which fluid is return fluid, which is forced out of the power section, through a valve and into a produced fluid annulus; with e.g., power fluid pumped by a pump on the surface.

(28) The present invention provides, in certain aspects, a method for pumping fluid from a wellbore, the fluid comprising production fluid, the wellbore extending from an earth surface down into the earth, the method including: installing a pumping system with a pump according to the present invention and with the pump, pumping production fluid from the wellbore, up the annulus, and out of the wellbore.

(29) The present invention provides, in certain aspects, a method for pumping fluid from a wellbore, the fluid comprising production fluid, the wellbore extending from an earth surface down into the earth, the method including: installing an outer tubular (e.g. casing or large tubing) in a wellbore; installing an inner tubing (e.g. production tubing or coiled tubing) within the outer tubular, an inner wall of the outer tubular and an outer wall of the inner tubing defining an annulus through which fluid is flowable; installing a system in the inner tubing, the system comprising a pumping system for pumping production fluid up the annulus and out of the wellbore, the pumping system including a pump, the pump comprising a retrievable reciprocating pump selectively disposable in the inner tubing, the pump having a power section for receiving power fluid and a power piston movable within the power section, the power piston reciprocable within the power section to provide reciprocal pumping action for pumping the production fluid, movement of the power piston drawing production fluid from the wellbore; and with the pump, pumping production fluid from the wellbore, up the annulus, and out of the wellbore.

(30) Certain changes can be made in the subject matter disclosed without departing from the spirit of this invention. The following claims are intended to cover the invention as broadly as legally possible in whatever form. The invention claimed herein is new and novel in accordance with 35 U.S.C. § 102 and satisfies the conditions for patentability in § 102; and is not obvious in accordance with 35 U.S.C. § 103 and satisfies the conditions for patentability in § 103. All patents and applications identified herein are incorporated fully herein.