US3922116A

US3922116A - Reversing mechanism for double-action hydraulic oil well pump

Info

Publication number: US3922116A
Application number: US460858A
Authority: US
Inventors: Toby Sydney Pugh
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1974-04-15
Filing date: 1974-04-15
Publication date: 1975-11-25
Anticipated expiration: 1992-11-25

Abstract

A valve system for controlling input and exhaust of power fluid to a dual action hydraulically actuated downhole pump utilizes a ported inner mandrel slidably mounted over the middle rod of the pump and actuated by the pump pistons, with a ported valve housing located annularly between the mandrel and the production tubing.

Description

United States Patent [191 Pugh [ Nov. 25, 1975 REVERSING MECHANISM FOR DOUBLE-ACTION HYDRAULIC 01L WELL PUMP [75] Inventor:

[73] Assignee: Dresser Industries, Inc., Dallas, Tex.

[22] Filed: Apr. 15, 1974 [21] Appl. No.2 460,858

Toby Sydney Pugh, Arlington, Tex.

[52] U.S. Cl. 417/393; 91/324; 91/352;

. 91/413 [51] Int. Cl. F04B 17/00; F1513 13/09 ['58] Field of Search 417/393, 394, 395, 401,

[56] References Cited UNITED STATES PATENTS 2/1966 Russell 417/393 3,652,187 3/1972 Loeffler 417/393 3,846,048 11/1974 Robbins, Jr .1 4l7/393 3,849,030 11/1974 McArthur et al 417/393 Primary ExaminerC. J. Husar Assistant ExaminerLeonard Smith Attorney, Agent, or Firm-Michael J. Caddell [5 7] ABSTRACT A valve system for controlling input and exhaust of power fluid to a dual action hydraulically actuated downhole pump utilizes a ported inner mandrel slidably mounted over the middle rod of the pump and actuated by the pump pistons, with a ported valve housing located annularly between the mandrel and the production tubing.

5 Claims, 3 Drawing Figures US. Patent N0v.25, 1975 Sheet1of2 3,922,116

I 'a 1 4A US. Patent Nov. 25, 1975 FIG. 2A

REVERSING MECHANISM FOR DOUBLE-ACTION HYDRAULIC OIL WELL PUMP BACKGROUND OF THE INVENTION In the production of oil from low pressure formations, it is often necessary when the well is not capable of flowing by itself to utilize oil well pumps lowered into the production tubing in the well. There are various and numerous types of production pumps one of which is the mechanical or sucker rod type. This pump is driven by vertical reciprocation of a sucker rod string inside the tubing. A common sucker rod pump may be capable of pumping 200-300 barrels per day from an average well.

An improved type of pump is the single action hydraulic pump which utilizes hydraulic power supplied to the subsurface pump by a power fluid which is pumped to the subsurface pump from equipment above ground at or near the wellhead. Such a pump on the average well may increase production to as much as 1,500 barrels per day.

A further improvement involves the use of the doubleaction hydraulic pump which is capable of increasing the production capacity of the pumped well to as much as 2,500 barrels of oil per day.

The use of a double-action hydrualic pump requires a complex and efficient valving system for good performance, dependability, and long wear in the borehole. The valving system must be capable of supplying power fluid to one piston while allowing the power fluid on the opposite piston to be expelled while also simultaneously one piston is pushing well fluid up the production string and the opposite piston is drawing fluid up from the formation by means of a suction stroke.

The present invention provides a dual reversing valve system which maximizes the efficiency of the doubleaction hydraulic pump by providing optimum timing and power fluid cycles through its porting system while also contributing to longer life, dependability and ease of manufacture because of its lack of unnecessary complexity. Furthermore, the present invention allows the use of maximum width pump pistons per given tubing size thereby further optimizing pumping efficiency. The prior art suffers in this respect in that a large portion of the effective piston surface area is used up by the passage of the valving mechanism therethrough. The deficiency is eliminated by this invention.

BRIEF DESCRlPTlON OF THE DRAWINGS FIG. 1 is a schematic view of a double-action hydraulic oil well pump;

FlGS. 2a and 2b illustrate a one-half section view of the valving system of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic cross-sectional view of a dual action hydraulic oil well pumping assembly located in a production tubing string 1 which is concentrically located in a producing wellbore 11.

The pumping assembly 10 consists generally of an upper piston assembly 2 and a lower piston assembly 3 connected to the upper piston assembly by middle rod 4. The reversing valve assembly 5 is located around rod 4 between the upper and lower piston assemblies. The piston assemblies and valving mechanism are slidably 2 and sealingly located in a pump barrel 6 secured inside the well tubing 1.

Pistons

2 and 3 in conjunction with pump barrel 6 form upper and

lower chambers

7 and 8 respectively and a power fluid chamber 9 between the pistons.

A producing formation 12 is penetrated by the wellbore 11 and flows oil under low pressure into the wellbore below the pumping mechanism 10. A well fluid pickup conduit 13 extends from the formation 12 to the 0 upper and

lower chambers

7 and 8. A pumped fluid conduit 14 extends from

chambers

7 and 8 to the surface to conduit pumped well fluid from the well. A power fluid conduit 15 extends from hydraulic power supply equipment at the surface to the power fluid chamber 9 via valving assembly 5.

Annular packings

24 and 25 provide sealing between the valve assembly 5 and the tubing 1.

Referring now to FIGS. 20 and 2b, a more detailed description of the valvin g assembly 5 will be given. The figures represent a one-half cross sectional view divided at the longitudinal centerline of the valving assembly and broken at common line a-a.

The valving assembly utilizes a tubular ported inner mandrel 16 slidably encircling middle rod 4. Mandrel 16 has an upper skirt 17 forming an annular space 17a between skirt l7 and the middle rod 4. A flow port 18 extends through skirt 17 at its upper end and one or more elongated slots 19 pass through the skirt below port 18. The lower end of mandrel 16 is identical to the upper end but in an inverted orientation, making mandrel 16 symmetrical about a lateral axis. The lower end of the mandrel also has a skirt 20, annular space 20a, port 21 and slots 22.

An annular bumper ring 23 encircles mandrel l6 and is held thereon by engagement in a matching annular channel formed in the outer wall of mandrel 16.

A vertically symmetrical valve housing assembly 26 is snugly mounted about the inner mandrel and adapted to allow slidable movement of the mandrel therein. The housing assembly 26 is generally cylindrical in shape and consists of an upper ported head 27, an upper ported connector 28, a central cylinder 29, a lower ported connector 30, and a lower ported head 31.

The upper and lower heads are each secured to sections of the pump barrel 6a and 6b, respectively. The heads each have a set of one or

more ports

32 and 33, respectively, passing therethrough.

The upper connector 28 is threadedly attached to upper head 27 and contains an annular shoulder 33 thereon which, in conjunction with the lower end 34 of upper head 27, serves to secure the annular packing 24 therebetween. Connector 28 has one or more ports 35 therethro'ugh which communicate with an annular relief area 36 formed in the connector inwardly from shoulder 33. Ports 35 are located so as to be able to communicate with ports 18 in the inner mandrel, while relief area 36 is adapted to communicate with slots 19 and also ports 18 during part of stroke of mandrel 16.

The central cylinder 29 is a cylindrical sleeve thread edly secured to upper connector 28 and slidably enclosing annular bumper ring 23. The lower connector 30 which is identical to upper connector 28 in an inverted orientation thereto, is threadedly secured to the central cylinder and has ports 37 and relief area 38 arranged to communicate with ports 21 and slots 22, re-

- spectively.

3 packing 25 similar to the attachment of packing 24 to the valve assembly. The lower head is threadedly secured to pump barrel 6b and contains one or more ports 39 therethrough located so as to communicate at times with ports 21 or slots 22.

While not illustrated in FIGS. and 2b, it is noted that

pistons

2 and 3 are secured to middle rod 4 and serve to form with pump barrel sections 6a and 6b upper and lower power fluid chambers 90 and 9b, respectively, below the upper piston and above the lower piston. Annular packings 24 and serve as pressure seals between the tubing ID and the upper and lower connectors, respectively. Also the lower end of upper connector 28 in conjunction with the upper end of lower connector provide the abutment means to receive bumper 23 and limit vertical movement of mandrel 16.

Referring again to FIG. 1, in typical operation, the double-action hydraulic pump 10 is actuated by supplying, under high pressure, power fluid down conduit 15, which conduit is pictured inside the tubing but which could be outside the tubing. The fluid is supplied to the reversing valve assembly which directs it to either the bottom face of the upper piston 2 or the upper face of the lower piston 3. Simultaneously while delivering the power fluid to one piston face, it exhausts through a check valve spent power fluid from the opposite face of the other piston. Also simultaneously, one piston chamber is communicated with the well fluid supply conduit 13 and the opposite piston chamber is communicated with the pumped fluid discharge conduit 14, which is shown inside the tubing but which could be outside the tubing or could actually be the tubing-casing annulus. Suitable check valves may be located in each of the conduits l3, l4 and 15 to prevent backflow.

The piston receiving power fluid application moves into its piston chamber thereby forcing out pumped well fluid while the opposite piston moves out of its piston chamber setting up a suction and drawing in well fluid from the formation. Upon reaching the piston stroke limit, the reversing valve switches power fluid from the pumping piston to the suction piston and the pump then performs the second half of the doubleaction pumping cycle.

At any point between the piston stroke limits, the pump assembly is simultaneously receiving power fluid, discharging spent power fluid, pumping well fluid to the surface, and drawing well fluid up to the pump from the formation.

The use of the valving system of this invention makes the above operation highly efficient and dependable. In operation, the valving assembly as shown in FIGS. 2a and 2b, is in position to receive power fluid through an inlet 41 in the tubing and apply the pressurized fluid through

ports

35 and 18, and annular space 170 to power chamber 90 where the power fluid starts to force the upper piston upward. This serves to push out well fluid located in the piston chamber 7 above piston 2 while it simultaneously brings the lower piston upward forcing out spent power fluid in chamber 9b atop piston 3 while creating a suction in chamber 8 below piston 3 and thereby drawing in well fluid to chamber 8.

Upon reaching a certain position in the upward stroke, the lower piston 3 will abut the lower skirt 20 of mandrel 16 and begin to carry it upward inside the housing assembly 26. A rapid upward movement and consequent possible damage to the valving assembly is prevented by the restricted damping action of the narrow annular passage 42 between the inner mandrel and upper connector 28. This passage provides fluidic resistance to flow of fluid trapped on top of bumper ring 23 and thereby acts as a dashpot effect to resist upward movement of the mandrel and piston assembly upward in the housing assembly.

Likewise, a corresponding annular restricted passage 43 below bumper 23 prevents an identical rapid movement downward on the downstroke portion of the pumping cycle.

As the piston and rod assembly and inner mandrel near the upper limit of the upstroke,

ports

39 and 35 cease to communicate with slots 22 and ports 18 and the moving inertia of the piston and rod assembly carries the assembly and the inner mandrel on upward until bumper ring 23 abuts the lower end of connector 28. At this instant port 32 is placed in communication with slot 19 and port 37 communicates with port 21 thereby putting pressurized power fluid onto the top of lower piston 3 and simultaneously opening to exhaust the spent power fluid below the upper piston 2 so that as piston 3 is forced downward the power fluid trapped below piston 2 may be discharged into the annulus through a check valve 40.

The downward movement of the piston and rod assembly also serves to pump well fluid upward to the surface and draw well fluid up from the well formation as previously described.

Upon reaching the lower limit of the pump downstroke, the upper piston 2 will abut the upper end of mandrel 16 thereby driving it downward until it is once again in the position as shown in FIGS. 2a and 2b whereupon the pumping cycle is completed and another cycle is ready to begin.

It should be noted that near the end of each upstroke and each downstroke, all of the ports are closed for a split second to prevent unwanted intercommunication between them and stalling of the pumping operation. The moving inertia of the piston and rod assembly and the inner mandrel is sufficient in each case to move the ports past this intentionally included dead spot and into the next pump stroke operation, thereby preventing short circuiting of the fluid flow channels.

Packing

24 and 25 further prevent fluid communication between the upper ports and between the lower ports.

Although a specific preferred embodiment of the present invention has been described in the detailed description above, the description is not intended to limit the invention to the particular forms of embodiments disclosed therein, since they are to be recognized as illustrative rather than restrictive and it will be obvious to those skilled in the art that the invention is not so limited. Thus, the invention is declared to cover all changes and modifications of the specific example of the invention herein disclosed for purposes of illustration which do not constitute departures from the spirit and scope. of the invention.

The embodiments of the invention in which an exclusive property' or privilege is claimed are defined as follows:

l. Valving mechanism for use in a double-acting hydraulic oil well pump having a central sliding piston rod with upper and lower pistons thereon located in a pump barrel, said valving mechanism comprising:

inner mandrel means snugly encircling the piston rod of the pump in slidable relationship therewith; port means passing through said inner mandrel means;

passing means between said inner mandrel means and the piston rod and adapted for communication with said port means;

housing means concentrically mounted about said inner manadrel means and adapted to allow sliding movement of said inner mandrel means therein; said housing means further adapted to be interconnected between and in axial alignment with two sections of pump barrel;

flow passage means through said housing means arranged to be placed in communication with said inner mandrel port means;

seal means between said housing means and the oil well tubing inner diameter; and,

hydraulic damping means between said inner mandrel means and said housing means arranged to provide fluidic resistance to rapid movement of said inner mandrel means with respect to said housing means.

2. The valving mechanism of claim 1 further comprising travel limit means between said inner mandrel means and said housing means arranged to limit upward and downward movement of said inner mandrel means in said housing means.

3. The valving mechanism of claim 1 wherein said damping means further comprises ring means securedly mounted on said inner mandrel means and extending into an inner annular chamber area in said housing means with restricted annular flow passages above and below said chamber area arranged to allow restricted fluid flow into and out of said chamber area in response to axial movement of said ring means through said chamber.

4. A reversing valve assembly for use in hydraulically actuated oil well pumps of the type having two pistons slidably mounted vertically in a pump barrel and connected by a central piston rod; said valve assembly comprising:

a cylindrical tubular inner mandrel slidably located about the central piston rod;

upper port means passing through the wall of said inner mandrel; upper passage means in the upper end of said inner mandrel communicating said upper port means with a chamber below the upper pump piston;

lower port means passing through the wall of said inner mandrel;

lower passage means communicating said lower port means with a chamber above the lower piston in the pump; generally cylindrical tubular housing means mounted externally on said inner mandrel and adapted to allow sliding movement of said mandrel therein;

6 upper exit port means passing through the wall of the upper portion of said housing means and arranged to be placed in communication with said mandrel upper port means;

upper entrance port means passing through the wall of the upper portion of said housing means below said upper exit port means and arranged to be placed in commuication with said mandrel upper port means;

upper packing means located in sealing abutment between said housing means and the inner wall of the well tubing, said upper packing means being located on said housing means between said upper exit port means and said upper entrance port means;

lower entrance port means passing through the wall of the lower portion of said housing means and arranged to be placed in communication with said mandrel lower port means;

lower exit port means passing through the wall of the lower portion of said housing means below said lower entrance port means and arranged to be placed in communication with said mandrel lower port means; and

lower packing means sealingly mounted between said housing means and the inner wall of the well tubing and located between said lower entrance port means and said lower exit port means;

said inner mandrel arranged between the pump pistons to be actuated upward and downward by abutment with the pistons between a first configuration and a second configuration in said housing means, wherein said first configuration places said upper entrance port means in communication with said mandrel upper port means and said lower exit port means in communication with said mandrel lower port means, and said second configuration places said upper exit port means in communication with said mandrel upper port means and said lower entrance port means in communication with said mandrel lower port means.

5. The reversing valve assembly of claim 4 further comprising hydraulic damping means between said inner mandrel and said housing means, said damping means comprising ring means mounted annularly on said inner mandrel and projecting into an hydraulic damping chamber formed in said housing means, said ring means adapted to move vertically in said chamber and substantially prevent flow of fluids between said ring means and said chamber wall, with restricted flow passages at the top and bottom of said chamber arranged to allow only a restricted flow of fluid from said chamber -and thereby retard movement of said ring means therein.

Claims

1. Valving mechanism for use in a double-acting hydraulic oil well pump having a central sliding piston rod with upper and lower pistons thereon located in a pump barrel, said valving mechanism comprising: inner mandrel means snugly encircling the piston rod of the pump in slidable relationship therewith; port means passing through said inner mandrel means; passing means between said inner mandrel means and the piston rod and adapted for communication with said port means; housing means concentrically mounted about said inner manadrel means and adapted to allow sliding movement of said inner mandrel means therein; said housing means further adapted to be interconnected between and in axial alignment with two sections of pump barrel; flow passage means through said housing means arranged to be placed in communication with said inner mandrel port means; seal means between said housing means and the oil well tubing inner diameter; and, hydraulic damping means between said inner mandrel means and said housing means arranged to provide fluidic resistance to rapid movement of said inner mandrel means with respect to said housing means.

4. A reversing valve assembly for use in hydraulically actuated oil well pumps of the type having two pistons slidably mounted vertically in a puMp barrel and connected by a central piston rod; said valve assembly comprising: a cylindrical tubular inner mandrel slidably located about the central piston rod; upper port means passing through the wall of said inner mandrel; upper passage means in the upper end of said inner mandrel communicating said upper port means with a chamber below the upper pump piston; lower port means passing through the wall of said inner mandrel; lower passage means communicating said lower port means with a chamber above the lower piston in the pump; generally cylindrical tubular housing means mounted externally on said inner mandrel and adapted to allow sliding movement of said mandrel therein; upper exit port means passing through the wall of the upper portion of said housing means and arranged to be placed in communication with said mandrel upper port means; upper entrance port means passing through the wall of the upper portion of said housing means below said upper exit port means and arranged to be placed in commuication with said mandrel upper port means; upper packing means located in sealing abutment between said housing means and the inner wall of the well tubing, said upper packing means being located on said housing means between said upper exit port means and said upper entrance port means; lower entrance port means passing through the wall of the lower portion of said housing means and arranged to be placed in communication with said mandrel lower port means; lower exit port means passing through the wall of the lower portion of said housing means below said lower entrance port means and arranged to be placed in communication with said mandrel lower port means; and lower packing means sealingly mounted between said housing means and the inner wall of the well tubing and located between said lower entrance port means and said lower exit port means; said inner mandrel arranged between the pump pistons to be actuated upward and downward by abutment with the pistons between a first configuration and a second configuration in said housing means, wherein said first configuration places said upper entrance port means in communication with said mandrel upper port means and said lower exit port means in communication with said mandrel lower port means, and said second configuration places said upper exit port means in communication with said mandrel upper port means and said lower entrance port means in communication with said mandrel lower port means.

5. The reversing valve assembly of claim 4 further comprising hydraulic damping means between said inner mandrel and said housing means, said damping means comprising ring means mounted annularly on said inner mandrel and projecting into an hydraulic damping chamber formed in said housing means, said ring means adapted to move vertically in said chamber and substantially prevent flow of fluids between said ring means and said chamber wall, with restricted flow passages at the top and bottom of said chamber arranged to allow only a restricted flow of fluid from said chamber and thereby retard movement of said ring means therein.