US3865516A

US3865516A - Fluid actuated down-hole pump

Info

Publication number: US3865516A
Application number: US385459A
Authority: US
Inventors: George K Roeder
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-08-03
Filing date: 1973-08-03
Publication date: 1975-02-11
Anticipated expiration: 1992-02-11

Abstract

A short down-hole fluid actuated pump assembly which includes a valve assembly, an engine, and a production pump. The valve assembly receives a source of power fluid from the surface of the earth. The production pump is reciprocatingly actuated by means of the engine which in turn receives a source of power fluid through the valve assembly. A piston, having a passageway formed therethrough, is connected to a hollow valve control rod and to a pump connecting rod. A seal tube receives the control rod therewithin and includes a seal means which isolates the tube from a power fluid inlet to thereby form a path of fluid flow from the valve assembly, to the seal tube, into and through the control rod, and to the bottom of the piston. This expedient substantially increases the permissible size of the piston with respect to the outside diameter of the engine cylinder while at the same time effectively shortens the length of the pump.

Description

O United States Patent 1191 1111 3,865,516 Roeder [45] Feb. 11, 1975 [54] FLUID ACTUATED DOWN-HOLE PUMP [76] Inventor: George K. Roeder, Box 4335, [57] ABSTRACT Odessa Tex 79760 A short down-hole fluid actuated pump assembly [22] Filed: Aug. 3, 1973 which includes a valve assembly, an engine, and a production pump. The valve assembly receives a source [21] Appl' No" 385459 of power fluid from the surface of the earth. The production pump is reciprocatingly actuated by means of [52] U.S. Cl. 417/403 the engine which in turn receives a source of power [51] Int. Cl. F04b 17/00 fluid through the valve assembly. A piston, having a [58] Field of Search 91/319, 225, 403; 417/403, passageway formed therethrough, is connected to a 417/404, 399 hollow valve control rod and to a pump connecting rod. A seal tube receives the control rod therewithin [56] References Cited and includes a seal means which isolates the tube from UNITED STATES PATENTS a power fluid inlet to thereby form a path of fluid flow from the valve assembly to the seal tube into and ,081,223 51937 C b l 417 404 119,736 6/1938 cgbgll 91 /31/9 x through tho Control foo, and to the bottom of the Pls' 2,204.12() 6/1940 Coben), 417/404 X ton. This expedient substantially increases the permis- 3,540,814 11/1970 Roeder 417/399 sible size of the piston with respect to the outside di- Prmary Examiner-William L. Freeh Assistant Examiner-Gregory Paul LaPointe Attorney, Agent, or Firm-Marcus L. Bates ameter ofthe engine cylinder while at the same time effectively shortens the length of the pump.

6 Claims, 10 Drawing Figures PMENTEUB' HWS Fna 1 FLUID ACTUATED DOWN-HOLE PUMP BACKGROUND OF THE INVENTION The present invention relates to down-hole fluid operated pump assemblies, sometimes called hydraulic pumping units. "Fluid operated pump systems do not require a reciprocating sucker-rod string such as used by conventional pumps, for example, in order to transmit the necessary force for the pumping action from the surface ofthe ground to the bottom hole pump. The pump system of the present invention generally requires a high pressure hydraulic pump which is located above the surface of the earth and which recirculates a portion of the produced fluid from the well back to the pump assembly located down-hole in the well. A valve assembly interconnects the high pressure fluid source with the engine of the pump assembly to move a pump connecting rod which in turn enables fluid to be forced from a production zone to the surface of the earth. This state of the art is adequately described in my prior U.S. Pat. Nos. 3,453,963; 3,517,714; 3,540,814; 3,625,288; 3,650,640, and 3,703,926; as well as in the prior art patents to C. .1. Coberly; namely, U.S Pat. Nos. 2,081,223; 2,230,830; and 2,338,903; to which reference is made for some of the operational details of the pump assembly.

As pointed out in my Us. Par. No. 3,540,814 the various prior art devices presently available include an engine or motor end, and it is common practice to conneet two production ends, or pumps, to one power piston. ln hydraulic pumping units of the type used in deep wells, the operating pressure requirements of the engine increases in proportion to the required hydrostatic head. On deep wells the pressure requirements sometimes reach a magnitude wherein further increase in operating pressure in order to attain a deeper well setting results in pump failure. Since the maximum operating pressure to which an engine of the present invention can be subjected is limited, the only remaining design expedient available in order to extract more power from the surface hydraulic pump is to increase the area and stroke of the piston located within the engine which drives the pump. This latter expedient has the obvious limitation of the physical size of the piston which can be located within the cylinder of an engine. In U.S. Pat. No. 3,540,814 there is set forth a downhole pump having an engine which enables an increase in the physical size of the piston which imparts an increased lifting force into the production pump. However, the improved pump is of excessive length for some pump cavities and accordingly, it is desirable that the pump length be shortened by providing the pump engine with improved design expedients which effectively attain this goal without losing the advantages of increased piston and cylinder area.

SUMMARY OF THE INVENTION The present invention relates to a down-hole fluid actuated pump assembly for use in lifting fluids from a fluid producing stratum associated with a well by utilizing hydraulic power or fluid provided from the surface ofthe ground and suitably conveyed to an engine associated with the pump assembly. The pump assembly generally is comprised of-an elongated cylindrical unit having an upper end connected to a power fluid source, an outlet connected to a produced fluid flow conduit, and a pump inlet connected to or in communication with the fluid producing stratum. This arrangement enables the fluid produced by the stratum to be lifted to the surface of the earth along with the spent power fluid from the engine.

The present invention advantageously permits an increased diameter of piston to be utilized in the engine by eliminating the heretofore required flow passageways located within the cylinder wall within which the engine piston reciprocates. The expedient is brought about by the provision of a hollow pilot valve rod having a free marginal end portion reciprocatingly received within a seal tube in a manner to form a flow passageway to the underside of the engine piston while the remaining upper side of the engine piston is flow connected to the valve means by a flow passageway located above the portion of the engine cylinder within which the piston reciprocates. Hence, the present invention enables a reduction in the overall length of the pump assembly as well as eliminates the necessity for conducting fluid flow through the wall which forms the engine cylinder, thereby enabling a larger cylinder bore to be incorporated within the engine than would other wise be possible.

Therefore, a primary object of this invention is to provide the engine of a down-hole pump assembly with means for increasing the piston area thereof so that power fluid can apply increased force to actuate a production pump, while at the same time the overall length of the engine is effectively reduced.

Another object of this invention is to provide a short down-hole pump assembly with an engine which utilizes a continuation of the housing of the fluid actuated pump as the engine cylinder.

A further object of the present invention is the provision of an engine associated with a fluid operated pump assembly which eliminates the necessity of passageways being formed within the cylinder wall ofthe engine assembly, and which can be used in a standard pump cavlty- Still another object of the present invention is the provision of improvements in seal means for a hollow valve control rod which is utilized to convey power fluid to one side of an engine piston. j

A still further object of the present invention is the provision of pump apparatus which enables an improved, more powerful engine to be designed which can be utilized with existing valve assemblies and production pumps in order to increase the lifting power of a down-hole hydraulic pump assembly.

Still another object of the present invention is the provision of an improved fluid path for a down-hole pump assembly of either the free or the fixed type.

A still further object of the present invention is to provide an improved fluid flow path for the engine of a down-hole pump which permits the maximum size piston to be used by elimination of flow passageways from the cylinder walls, and which permits a substantial reduction in the length of the pump assembly.

Still another object of the present invention is the provision of a flow system for the engine of a downhole pump which enables reduction in the length of the engine.

The above objects are attained in accordance with the present invention by the provision of a fluid operated pump assembly fabricated in a manner essentially as outlined in the above summary and abstract. Other objects and advantages will become apparent to those skilled in the art as the details of construction and operation are hereinafter more fully described and claimed.

BRIEF DESCRIPTION OF THE DRAWINGSA FIG. I is a longitudinal, fragmentary, part crosssectional view of an improved fluid actuated pump assembly which has been fabricated essentially in accordance with the present invention with the pump assembly being disclosed in one of its operative configurations;

FIG. 2 is an enlarged, fragmentary, longitudinal, cross-sectional representation of the present invention;

FIG. 3 is an enlarged, fragmentary, longitudinal, cross-sectional view of one embodiment of the invention disclosed in FIG. 2;

FIG. 4 is a cross-sectional View showing the apparatus of FIG. 3 as it appears when in a different operative configuration;

FIG. 5 is a broken, enlarged, longitudinal, crosssectional view of a detail of a fluid actuated pump assembly made in accordance with the present invention;

FIG. 6 is a cross-sectional view of the apparatus disclosed in FIG. 7;

FIG. 7 is a detailed, enlarged, side elevational view of part of the short bottom hole pump made in accorodance with the present invention;

FIG. 8 is an enlarged, cross-sectional view illustrating the details of the apparatus disclosed in FIG. 9;

FIG. 9 is a detailed, enlarged, side elevational view of the illustration seen in FIG. 8; and,

FIG. l0 is an end view of the apparatus disclosed in FIG. 8 and 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. l the arrow at numeral l0 broadly illustrates a short bottom hole pump located downhole in a borehole. The borehole is cased at l2 so that a seating shoe assembly can be operatively installed adjacent to a production zone. A surface return tubing 16 returns produced and spent power fluid to the surface of the earth. Production fluid at 18 enters a standing valve assembly 20 and flows into the hydraulic pump assembly located within power tubing 22.

The pump assembly y24 is of the free type and therefore includes a packer nose assembly 26 having a check valve stem 28 located immediately above the illustrated inlet ports which in turn are located above the illustrated spaced packer cups 30. Packer connector 32 connects the nose assembly to the remainder of the pump assembly by means of an extension nipple 34. Seal tube 35 is axially positioned within the extension nipple and forms an annular settling chamber 36 therewith.

Power fluid inlet ports 37 are located above a standard 0-ring seal collar 38 while spent power fluid exhaust 39 are located below the 0-ring seal collar in the usual manner.

The hydraulic pump assembly includes an engine valve assembly 40 connected to an engine cylinder assembly as indicated by the numeral 42 in FIG. 2.

Production exhaust ports

43 and 45 are spaced above and below a production end 44 of the pump assembly, the details of which are set forth in U.S. Pat. No. 3,540,814.

As seen in the illustration of FIG. 2 -4, in conjunction with FIG. 1, wherein so far as is possible, like numerals refer to similar or like elements, the before mentioned power fluid inlet 37 can be arranged in the alternate position seen illustrated at 46 in FIG. 4,as may be required for conventional type pumps. The upper extremity of the engine valve assembly is preferably threaded at 48 to provide for attachment to a power tubing string. The sub 50 can be changed to packer connector as illustrated in FIG. 2 as may be desired. The main body 49 of the valve assembly threadedlyengages the spaced upper and lower subs 50, 5l. Longitudinally extending hollow valve control rod 52 is provided with the illustrated spaced flats 53; 53' thereon with the marginal free end portion of the rod being freely and reciprocatingly received within the interior of the before mentioned seal tube, while the remaining or fixed end of the rod is threadedly connected to an engine piston 54. The piston divides the engine cylinder into upper and

lower cylinder chambers

55, 56 respectively. Annular downwardly opening passageway 57 interconnects the first longitudinally disposed passageway 58 with the upper cylinder chamber by means of member 59, which is removably affixed to the lower sub member. Control sleeve 60 is supported by and is affixed to member 59 and sealingly engages the reciprocating pilot rod in a slidably sealed relationship therewithin, as will be explained in greater detail later Port 6l communicates annulus 62 with port 63 which in turn is flow connected to passageway 64 and to the exhaust port 39. Upper and lower ports 65 and 65', respectively, are formed within the sleeve. Port 65' communicates annulus 66 with annulus 62 by means of flat 53 when the sliding valve 67 is in the upper position. Variable annulus 69 is flow connected to upper port 65 by the upper flat 53' when the control rod is in a lowermost position. Sliding valve assembly 67 is provided with radial ports 68 which communicates

annulus

69 and 70 with flow passageway 168.

Reciprocating annulus 7l is formed between the spaced enlargements of the sliding valve assembly, one of which is seen at 72. Port 73 communicates with annulus 74, while annulus 75 is separated from

annular passageway

70, 74, and 76, while the latter are always in communication with one another. Annulus 75 is flow connected to

passageway

168 and 77.

The longitudinally extending axial bore of the valve i body accordingly is comprised of small bore 79 which preferably is inthe form ofa seal sleeve 97 as seen illustrated in FIG. 5, for sealing engages the pilot rod and preventing flow of fluid between power fluid inlet 76 and seal tube chamber 78. The axial bore enlarges at 79' and again at 80 to form the before mentioned

annulus

74 and 76. Within the large counterbore 80 there is slidably received in a reciprocating manner the upper marginal end portion of the sliding pilot valve assembly. Ports 73 facilitates flow into ports 82, which is flow connected to passageway 58, which in turn communicates with annular passageway 57.

The upper extremity 83 of the sliding valve assembly is abuttingly received against shoulder 84. Spaced shoulders 86, 87 form the before mentioned traveling annulus 7l, while spaced relatively

movable shoulder

88, 89 when spaced or stroked apart as in FIG. 3, form annulus 69 therebetween.

Flat 90 forms a flow path which enables flat 53 to communicate annulus 66 with exhaust port 6l. Flat 90 further enables flat 53 to form a tlow path from annulus 66, flat 90, port 65, flat 53' to power fluid annulus 70. Sleeve 60 sealingly engages the rod along the area indicated by the numeral at 91 so as to prevent fluid flow thereacross.

As seen in the detailed embodiment of FIG. 5, seal tube 35 is concentrically received within its extension nipple 134. Retainer bushing 93 is connected to the upper adapter 92 and freely receives the pilot rod (not shown) therewithin with the pilot rod being received in close tolerance relationship at axial passageway 99 formed within the seal sleeve 97. The adapter is provided with threads at 98 so that it can threadedly engage the upper end of a valve body in a manner similar to the illustration of FIG. 2.

In operation, the pump is run downhole on a tubing string, or alternatively, if it is of the free type, the pump may be pumped downhole in a manner known to those skilled in the art, and as more fully explained in my U.S. Pat. No. 3,540,814.

Power fluid enters

inlet port

37 or 46, depending upon the configuration of the particular embodiment, and flows into

annulus

76, 70, and 69; and through ports 68, 68'; where the flow can proceed in accordance with the relative posiiton of the sliding valve element. Assuming that the sliding valve element is in the illustrated position of either FIGS. 2 or 3, the flow from the variable annulus 69 can proceed through

ports

68, 63, and into passageway 168; annulus 75; passageway 77; seal tube annulus 78; and into the interior of the pilot or control rod where the flow continues on down through the rod, through the engine piston, and into lower cylinder chamber 56 thereby forcing the piston to move in an upward direction carrying the pilot rod therewith. At the same time spent power fluid exhausts from upper cylinder chamber 55, and flows through annulus 57, into the longitudinal flow passageway 58, where the fluid emerges through port 82, flows through traveling annulus 71, and out through exhaust port 39.

As the engine piston upstrokes and nears its uppermost position, the lowermost flat 53

interconnects annulus

66 and 62 by means of ports 6land 65', causing reduced fluid pressure within annulus 66 because of exliaustl passageway 64 being flow connected thereto, thereby driving the sliding valve element in a downward dir etionwdue toit-hempressuie differential ofthe fluid pressure thereacross.

As the sliding valve assumes the illustrated position of FIG. 4, power fluid must now flow from annulus 76, through radial port 82, first longitudinal passageway 58, and into engine upper annulus 57 where the power fluid is effected in upper piston chamber 55, thereby driving the piston in a downward direction. At this time the spent fluid is free to flow from lower chamber 56, through the passageways in the piston, through the interior of the pilot rod, through seal tube annulus 78, passageway 77, into annulus 75, through passageway 168, into traveling annular chamber 7l, and out through exhaust ports 39.

As the piston approaches its lower limit of travel, uppermost flat 53 is brought into position to interconnect port 65 with annulus 70 thereby causing the control valve element to be shifted into its uppermost position because of the pressure differential thereacross, thereby causing the engine piston to again reverse its direction of travel. The pump assembly has now been returned to the configuration seen illustrated in FIGS. 2 and 3. Hence it will now be appreciated that the traveling valve element 72 alternately connects a first and second flow passageway to power fluid and exhaust port, with the first and second flow passages being flow connected to the upper and lower cylinder chambers` so that the engine piston reciprocates with a double action.

By the provision of a seal 79 located between the power fluid chamber 76 and the seal tube chamber 78, the distance between the 0-ring seal collar and the seating shoe assembly is effectively shortened thereby enabling the pump assembly to be used in a standard pump cavity. This expedient enables the packing box heretofore located in underlying relationship respective of the valve assembly to be relocated above the valve assembly, thereby reducing the length of the valve end engine a proportionate amount.

Ari important contribution to the improvement in the pump assembly lies in the novel design expedients incorporated into the control bushing 60 and the traveling valve element 67. It will be noted in the embodiments of FIGS. 2-4 and 6-10 that the bushing sealingly engages the control rod while the traveling valve element sealingly engages the axial bore of the valve assembly housing. The interior of the traveling valve element is provided with the illustrated spiral groove 267 which forms a small controlled pressure relief flow passageway in order to prevent the valve element from becoming locked into an intermediate position. The spiral commences at the lower terminal end of the valve element and extends slightly past ports 68, thereby leaving area 167 for sealingly engaging the control sleeve when the valve element is in the lowermost position.

When the valve 67 is in the position seen illustrated in FIG. 3, the spiral groove 267 provides a controlled supply of power fluid from chamber 69 into the charnber 66 thereby overcoming any pressure differential effected across the valve element due to leakage of power fluid from chamber 66 through the seal formed between the control rod and the control sleeve. For example, high pressure fluid flow occurs from chamber 66, through ports 65, 65', along the exterior surface of the control rod, through passageway 61, into chamber 62, and then into the exhaust passageway 64 by means of port 63.

When the valve element is shifted into the position seen illustrated in FIG. 4, the seal area 167 of the valve element theoretically prevents high pressure fluid from flowing from passageway 70, along the spiral groove, and under the valve element where premature movement of the valve element could otherwise be effected by the presence of the high pressure fluid leakage. In actual practice, especially when the valve assembly has become worn through long time in service, it has been found expedient to overcome this potential problem associated with the fluid leakage by the provision of a relatively small bleed port 68 which bleeds any fluid leakage into the exhaust passageway by intersecting the flow path of the leakage, so that, fluid flow from 70 across seal surface 167 will follow the path of least resistance which is through ports 68, into port 68', and into the exhaust passageway 168. It will be noted that port 68 is closed when the valve element is shifted into its upper position, as seen illustrated in FIG. 3. Hence, port 68 is completely shut off to high pressure fluid flow instantaneously with the spiral groove being opened to a source of high pressure fluid flow upon the initial upward movement of the traveling valve element.

Flat 90 flow communicates the exterior surface of the control bushing between

apertures

65, 65 to enable power fluid to more efficiently flow across the control rod flat when chamber 66 is flow connected to either the exhaust or to the power fluid port,

Shoulders

86 and 87 provide for part of the traveling annulus for alternately connecting together the exhaust and second flow passageway, and the exhausttand first flow passageway.

I claim:

1. A fluid actuated pump assembly having a valve assembly, a power fluid chamber, an engine, and a production pump, a formation fluid inlet flow means and a produced fluid flow means flow attached to said pump; means by which a source of power fluid can be flow connected to the power fluid chamber of the valve assembly; and a spent power fluid outlet; the improvement comprising:

said engine having a piston reciprocatingly received within an engine cylinder, said piston dividing said engine cylinder into an upper cylinder chamber and a lower cylinder chamber; a valve control rod having an axial flow passageway formed therethrough, said control rod being connected to 'said piston and extending through the valve assembly for controlling the action of the valve assembly which in turn controls the fluid flow path to said engine; a seal tube supported by said valve assembly and spaced from said control rod, said control rod being received within said seal tube; seal means reciprocatingly receiving said control rod therethrough for preventing power fluid flow from the power fluid chamber, along the exterior surface of the rod, and into said seal tube; a connecting rod connected between said piston and the production pump for actuating the production pump;

means forming a first flow passageway from-the valve assembly to said upper cylinder chamber, means forming a second flow passageway from the valve assembly to the interior of said seal tube, and into the interior of said hollow valve control rod,

through said piston, and into said lower cylinder chamber; means forming an exhaust flow passageway through which spent power fluid from the engine can flow;

said valve assembly includes a control sleeve axially aligned with and reciprocatingly receiving said control rod therethrough;

a valve element concentrically arranged respective to said control rod and said control sleeve and movable from a first to a second position, a marginal length of said control sleeve being received within a marginal length of said valve element;

spaced shoulders on said valve element forming a traveling annulus for flow connecting said exhaustv passageway to said second passageway when said valve element is in the first position, and for flow connecting said exhaust passageway to said first passageway when said valve element is in the second position;

a spiral groove formed on a marginal longitudinal interior surface of said valve element which slidably contacts said marginal exterior surface of said control sleeve to provide for a bleed passageway through which power fluid can flow;

so that said valve assembly connects said first flow passageway to said exhaust flow passageway for conducting spent power fluid away from said upper chamber; and to conduct power fluid flow to said second flow passageway in order to cause said piston to reciprocate in a first direction; and, said valve assembly connects said first flow passageway to conduct power fluid flow to said upper chamber and to conduct spent power fluid flow away from said second flow passageway in order to cause said piston to reciprocate in a second direction.

2. The pump assembly of claim l, wherein said control sleeve has a lower marginal length thereof supported by said valve body, said lower marginal length sealingly engaging an outer marginal length of said control rod for preventing fluid flow from said upper cylinder, along the exterior surface of the rod, and into said valve assembly.

3. A fluid actuated pump assembly comprising a valve assembly, a fluid actuated engine, and a production pump;

said valve assembly providing flow control means for said engine and including a valve body, a traveling valve element reciprocatingly received within said body and movable between a first and second flow control position, an axial passageway formed through said valve element;

said engine having a cylinder, a piston reciprocatingly received within said cylinder and forming upper and lower cylinder chambers; a valve control rod attached to said piston and having a marginal free end portion extending through said axial passageway, a power fluid flow passageway formed between said rod and said valve element; means forming a power fluid inlet which is in flow communication with said power fluid flow passageway;

a seal tube for reciprocatingly receiving a free marginal length of said control rod and forming a flow passageway therebetween;

a seal means separating said power fluid flow passageway from said seal tube flow passageway, a flow passageway formed from said power fluid flow passageway to said seal tube flow passageway;

said valve control rod having means associated with said power fluid flow passageway for causing said valve element to assume said first flow position and said second flow position in response to reciprocation of said piston;

said valve element being concentrically arranged respective to said control rod and said control sleeve with a marginal length of said control sleeve being received within a marginal length of said valve element;

spaced shoulders on said valve element forming a traveling annulus for flow connecting said exhaust passageway to said second passageway when said valve element is in the first position;

said valve element is provided with a spiral groove on the marginal longitudinal interior surface which slidably contacts said marginal exterior surface of said control sleeve to provide for a bleed passageway through which power fluid can flow;

a flow passageway means flow connecting said upper cylinder chamber with said valve element; a flow passageway means flow connecting said seal tube flow passageway with said valve element; an exhaust flow passageway means connecting said valve element to exhaust spent power fluid from said engine; a rod flow passageway means formed from said lower piston chamber, through said piston, through said valve control rod, and into said seal tube flow passageway;

so that when said control rod moves said valve ele ment to the first position, power fluid flows from said power fluid inlet, through said valve assembly, to said seal tube flow passageway, and to said lower cylinder chamber causing the piston to upstroke while fluid flows said upper piston chamber, through said valve assembly, and through said exhaust flow passageway;

and, as the control rod moves up, the valve element shifts to the second position, causing power fluid to flow from said power fluid inlet, through said valve assembly, into the upper piston chamber to cause the piston to downstroke while fluid flows from said lower cylinder chamber, into said seal tube flow passageway, through said valve assembly, and through said exhaust passageway.

4. The pump assembly of claim 3 wherein said control sleeve has a lower marginal length supported by said valve body, said lower marginal length sealingly engaging an outer marginal length of said control rod for preventing fluid flow from said upper cylinder into said valve assembly.

5. ln a fluid actuated pump assembly having a valve assembly, an engine, and a production pump, wherein the valve assembly is flow connected to a supply of power fluid and to an exhaust port in a manner to cause the engine to reciprocate the production pump, so that the pump can produce fluid from a fluid bearing strata located downhole in a borehole, the improvement comprising:

said valve assembly including a body having an axial bore therethrough, said engine having a control rod extending therefrom which is reciprocatingly reccived within the axial bore, a control sleeve, a reciprocating valve element; said control sleeve being affixed to said valve body; said valve body, said control sleeve, said valve element, and said control rod being concentrically arranged relative to one another with a marginal length of said rod being slidably received in sealed relationship respective to a marginal length of said control sleeve and spaced from said valve element;

said valve element having a marginal length which sealingly engages the surface of the axial bore and a marginal length which sealingly engages a marginal exterial surface of said control sleeve so that a variable annular fluid chamber is jointly formed by the valve body, control sleeve, and valve element; means forming a power fluid inlet chamber within said valve element;

means on said control rod for alternately connecting said variable annular chamber to said exhaust port and to said power fluid inlet chamber in response to reciprocation of the engine for causing said valve element to reciprocate between a lowermost and an uppermost position;

a spiral groove forming a controlled flow passageway between said valve element and said control sleeve for flow of power fluid from said power fluid inlet chamber into said variable annular fluid chamber when said valve element is reciprocated into an uppermost position;

means forming a bleed port for connecting said variable annular tluid chamber to said exhaust port when said valve element is in a lowermost position;

said controlled flow passageway being spaced from said power fluid chamber by said marginal surface of said control sleeve which sealingly engages said valve clement when said valve element is in a lowermost position, so that leakage of power fluid across the last recited sealing surfaces is exhausted from said variable annular fluid chamber;

and means by which said valve element causes said valve assembly to alternately connect the power fluid passageway and the exhaust port of the engine to the power fluid inlet passageway and to the exhaust port of the valve assembly as the valve element reciprocates.

6. The improvement of claim 5 wherein said spiral groove is provided on the marginal longitudinal interior surface of said valve element which slidably contacts said marginal exterior surface of said control sleeve to provide for a bleed passageway through which power fluid can flow.

Claims

1. A fluid actuated pump assembly having a valve assembly, a power fluid chamber, an engine, and a production pump, a formation fluid inlet flow means and a produced fluid flow means flow attached to said pump; means by which a source of power fluid can be flow connected to the power fluid chamber of the valve assembly; and a spent power fluid outlet; the improvement comprising: said engine having a piston reciprocatingly received within an engine cylinder, said piston dividing said engine cylinder into an upper cylinder chamber and a lower cylinder chamber; a valve control rod having an axial flow passageway formed therethrough, said control rod being connected to said piston and extending through the valve assembly for controlling the action of the valve assembly which in turn controls the fluid flow path to said engine; a seal tube supported by said valve assembly and spaced from said control rod, said control rod being received within said seal tube; seal means reciprocatingly receiving said control rod therethrough for preventing power fluid flow from the power fluid chamber, along the exterior surface of the rod, and into said seal tube; a connecting rod connected between said piston and the production pump for actuating the production pump; means forming a first flow passageway from the valve assembly to said upper cylinder chamber, means forming a second flow passageway from the valve assembly to the interior of said seal tube, and into the interior of said hollow valve control rod, through said piston, and into said lower cylinder chamber; means forming an exhaust flow passageway through which spent power fluid from the engine can flow; said valve assembly includes a control sleeve axially aligned with and reciprocatiNgly receiving said control rod therethrough; a valve element concentrically arranged respective to said control rod and said control sleeve and movable from a first to a second position, a marginal length of said control sleeve being received within a marginal length of said valve element; spaced shoulders on said valve element forming a traveling annulus for flow connecting said exhaust passageway to said second passageway when said valve element is in the first position, and for flow connecting said exhaust passageway to said first passageway when said valve element is in the second position; a spiral groove formed on a marginal longitudinal interior surface of said valve element which slidably contacts said marginal exterior surface of said control sleeve to provide for a bleed passageway through which power fluid can flow; so that said valve assembly connects said first flow passageway to said exhaust flow passageway for conducting spent power fluid away from said upper chamber; and to conduct power fluid flow to said second flow passageway in order to cause said piston to reciprocate in a first direction; and, said valve assembly connects said first flow passageway to conduct power fluid flow to said upper chamber and to conduct spent power fluid flow away from said second flow passageway in order to cause said piston to reciprocate in a second direction.

2. The pump assembly of claim 1, wherein said control sleeve has a lower marginal length thereof supported by said valve body, said lower marginal length sealingly engaging an outer marginal length of said control rod for preventing fluid flow from said upper cylinder, along the exterior surface of the rod, and into said valve assembly.

3. A fluid actuated pump assembly comprising a valve assembly, a fluid actuated engine, and a production pump; said valve assembly providing flow control means for said engine and including a valve body, a traveling valve element reciprocatingly received within said body and movable between a first and second flow control position, an axial passageway formed through said valve element; said engine having a cylinder, a piston reciprocatingly received within said cylinder and forming upper and lower cylinder chambers; a valve control rod attached to said piston and having a marginal free end portion extending through said axial passageway, a power fluid flow passageway formed between said rod and said valve element; means forming a power fluid inlet which is in flow communication with said power fluid flow passageway; a seal tube for reciprocatingly receiving a free marginal length of said control rod and forming a flow passageway therebetween; a seal means separating said power fluid flow passageway from said seal tube flow passageway, a flow passageway formed from said power fluid flow passageway to said seal tube flow passageway; said valve control rod having means associated with said power fluid flow passageway for causing said valve element to assume said first flow position and said second flow position in response to reciprocation of said piston; said valve assembly includes a control sleeve axially aligned with and reciprocatingly receiving said control rod therethrough; said valve element being concentrically arranged respective to said control rod and said control sleeve with a marginal length of said control sleeve being received within a marginal length of said valve element; spaced shoulders on said valve element forming a traveling annulus for flow connecting said exhaust passageway to said second passageway when said valve element is in the first position; said valve element is provided with a spiral groove on the marginal longitudinal interior surface which slidably contacts said marginal exterior surface of said control sleeve to provide for a bleed passageway through which power fluid can flow; a flow passageway means flow connecting said upper cylinder chamber with said valve element; A flow passageway means flow connecting said seal tube flow passageway with said valve element; an exhaust flow passageway means connecting said valve element to exhaust spent power fluid from said engine; a rod flow passageway means formed from said lower piston chamber, through said piston, through said valve control rod, and into said seal tube flow passageway; so that when said control rod moves said valve element to the first position, power fluid flows from said power fluid inlet, through said valve assembly, to said seal tube flow passageway, and to said lower cylinder chamber causing the piston to upstroke while fluid flows said upper piston chamber, through said valve assembly, and through said exhaust flow passageway; and, as the control rod moves up, the valve element shifts to the second position, causing power fluid to flow from said power fluid inlet, through said valve assembly, into the upper piston chamber to cause the piston to downstroke while fluid flows from said lower cylinder chamber, into said seal tube flow passageway, through said valve assembly, and through said exhaust passageway.

5. In a fluid actuated pump assembly having a valve assembly, an engine, and a production pump, wherein the valve assembly is flow connected to a supply of power fluid and to an exhaust port in a manner to cause the engine to reciprocate the production pump, so that the pump can produce fluid from a fluid bearing strata located downhole in a borehole, the improvement comprising: said valve assembly including a body having an axial bore therethrough, said engine having a control rod extending therefrom which is reciprocatingly received within the axial bore, a control sleeve, a reciprocating valve element; said control sleeve being affixed to said valve body; said valve body, said control sleeve, said valve element, and said control rod being concentrically arranged relative to one another with a marginal length of said rod being slidably received in sealed relationship respective to a marginal length of said control sleeve and spaced from said valve element; said valve element having a marginal length which sealingly engages the surface of the axial bore and a marginal length which sealingly engages a marginal exterial surface of said control sleeve so that a variable annular fluid chamber is jointly formed by the valve body, control sleeve, and valve element; means forming a power fluid inlet chamber within said valve element; means on said control rod for alternately connecting said variable annular chamber to said exhaust port and to said power fluid inlet chamber in response to reciprocation of the engine for causing said valve element to reciprocate between a lowermost and an uppermost position; a spiral groove forming a controlled flow passageway between said valve element and said control sleeve for flow of power fluid from said power fluid inlet chamber into said variable annular fluid chamber when said valve element is reciprocated into an uppermost position; means forming a bleed port for connecting said variable annular fluid chamber to said exhaust port when said valve element is in a lowermost position; said controlled flow passageway being spaced from said power fluid chamber by said marginal surface of said control sleeve which sealingly engages said valve element when said valve element is in a lowermost position, so that leakage of power fluid across the last recited sealing surfaces is exhausted from said variable annular fluid chamber; and means by which said valve element causes said valve assembly to alternately connect the power fluid passageway and the exhaust port of the engine to the power fluid inlet passageway and to the exhaust port of the valve assembly as the valve element reciprocates.