US2917000A - Subsurface hydraulic pump assembly - Google Patents

Description

Dec. 15, 1959 c. L. ENGLISH SUB-SURFACE HYDRAULIC PUMP ASSEMBLY Filed 0st. 30. 1957 INVENTOR.

CHAeLEs E/vqu'sH Fig ATTOFNFY 2,917,000 SUBSURFACE HYDRAULIC PUMP ASSEMBL Charles 1.. English, Tulsa, Okla. Application October 30, 1957, Serial No. 693,443 8 lClaims. (Cl. 103-46) This invention relates to improvements in subsurface fluid operated pump assemblies of the type used in pumping oil wells.

As it is Well known in the art, subsurface hydraulic pumps are frequently used to pump oil wells. One of the most popular methods of installing hydraulic pumps is to suspend the pumping unit on the lower end of a string of small tubing (commonly known as the power or macaroni string) within either a large string of production tubing or the well casing. The pumping unit is usually seated at its lower end in a seating nipple or shoe in the larger string of tubing in such a manner that the lower, pumping, end of the hydraulic pumping unit will communicate with fluid standing in the well. Power fluid is supplied through the macaroni string, and the pumping unit forces well fluids upwardly through the annulus between the macaroni string and the well tubing or casing.

One of the primary objections to this type of pump installation, particularly in deep wells, is the problem of unseating the pumping unit when it is necessary to remove the pumping unit from the well. At the present time, the pumping unit is unseated by pulling upwardly on the macaroni string. Invariably the seat of the pumping unit is tightly wedged in the seating shoe or nipple of the large string of tubing, and substantial force must be applied to unseat the pumping unit. The macaroni string is ordinarily retained as small in diameter and as light in weight as possible, and, particularly in deep well installations, the macaroni string is not sufliciently strong to unseat the pumping unit without danger of parting the string.

The present invention contemplates a novel pump assembly wherein the pumping unit may be unseated by the use of hydraulic force supplied from the power tubing or macaroni string. I contemplate packing off the medial portion of the pumping unit to the larger string of tubing to provide an enclosed annular chamber around the lower portion of the pumping unit. High pressure power fluid from the macaroni string is directed to this chamber and will react on the packer to unseat the pumping unit when the weight of the macaroni string is removed from the unit.

An important object of this invention is to provide a fluid operated pump assembly wherein the pumping unit may be unseated without either the danger of parting the power tubing, or changing the direction of flow of power fluid to the unit.

Another object of this invention is to minimize the strength requirements for the power tubing in a subsurface fluid operated pump assembly.

A further object of this invention is to increase the depth at which fluid operated pump installations may be made.

A still further object of this invention is to provide a fluid operated pumping unit which may be easily installed in a well tubing which previously received a sucker rod type pump.

ited States Patent 0 through ports 44 in the 2,917,000 Patented Dec. 15, 1959 ice Another object of this invention is to provide a fluid operated pump assembly which is simple in construction and may be economically manufactured.

Other objects and advantages of the invention will be evident from the following detailed description, when read in conjunction with the accompanying drawings which illustrate my invention.

In the drawings:

Figure 1 is a vertical sectional view of a fluid operated pump assembly constructed in accordance with this invent1on.

Figure 2 is a transverse sectional view as taken along lines 22 of Fig. 1.

Referring to the drawings in detail, reference character 4 designates a large string of well tubing or a well casing extending downwardly in a well bore (not shown) to below the level of fluid standing in the well. A collar 6 is threadedly secured on the lower end of the tubing 4 to support a pump housing 8 on the lower end of the tubing. The pump housing 8 is threadedly secured in the lower end of the collar 6 and is usually slightly smaller in diameter than the tubing 4. However, the housing 8 may be the same diameter as the tubing 4 and may be considered a part of the well tubing or casing. A seating nipple 10 is threadedly secured on the lower end of the housing 8 and has the usual tapered inner bore 12 of a smaller diameter than the diameter of either the housing 8 or well tubing 4. A tail pipe 14 or the like may be secured on the lower end of the nipple 10 if desired.

A combination seating shoe and standing valve assembly, generally designated by reference character 16, is inserted in the seating nipple 10. The assembly 16 has an outer tapered periphery at the upper end 18 thereof to conform to the tapered bore 12 of the nipple 10 and support the assembly 16 in the nipple 10. An upwardly opening standing valve 20 is supported in the lower portion of the assembly 16 to alternately open and close the inner bore 22 of the assembly and prevent a downward flow of fluid from the housing 8. The bore 22 of the assembly 16 serves as the inlet for well fluid into the housing 8.

An elongated hydraulic pumping unit 24 is inserted in the large tubing 4 and extends downwardly through the housing 8. The pumping unit 24 includes a hydraulic motor 26 comprising a motor cylinder 28 slidingly receiving a piston assembly 30. The piston assembly 30 contains the usual valves (not shown) to control the flow of fluid through ports 31 in the piston to the upper end of the motor cylinder 28. In the type of motor 28 illustrated, high pressurefluid is continuously directed into the lower end of the cylinder 28, as will be hereinafter set forth, and is alternately directed to the upper end of the cylinder through the piston assembly 30 to provide a reciprocation of the assembly 30 in the cylinder 28.

The lower end of the motor cylinder 28 :is internally threaded for connection with the upper end of a tubular middle plug 32. The lower end of the middle plug 32 is in turn threadedly connected to the cylinder 34 of the pump end 36 of the pumping unit 24. A tubular pump piston assembly 38, containing the usual travelling valve (not shown), is slidingly disposed in the pump cylinder 34 and is connected to the motor piston assembly 30 by means of a tubular connecting rod 40. The rod 40 extends through the inner bore 42 of the middle plug 32 and is hollow to conduct power fluid exhausing from the motor 26 downwardly to the pump cylinder 34. This exhausting power fluid is discharged pump piston assembly 38 into the upper portion of the pump cylinder 34 to join with the well fluids being pumped.

A suitable seat 46 is. formed on the lower end of the pump end 36 to mate with the tapered inner bore 48 in the upper end of the seating shoe assembly 16. It will be observed that the seat 46 is smaller in diameter than the. inner diameter'ofthe pump housing 8; Also, the seat 46 includes a conventional standing valve (not shown), and forms an inlet therethroughfor well fluid to the pumping unit 24.

The middle plug 32 contains suitable packing 50 in the upper portion thereof around the rod 40 to prevent communication between the, motor cylinder 28 and the pump cylinder 34. The packing 50 is retained in the proper position by a retaining. ring 52 supported on a complementary shoulder in the bore- 42 and a tubular nut 54 threadedly secured in the upper end of the bore 42. A plurality of outlet ports- 56 (see Fig. 2) extend transversely through the medial portion of the middle plug 32 directly below the packing 50 to provide outlets for fluid being pumped from the pump cylinder 34 upwardly through the bore 42. It will be observed that the outlet ports 56 communicate with the large tubing 4 to direct the fluids being pumped upwardly through the large tubing.

A suitable packer 58 is secured around the middle plug 32 below the. outlet ports 56, and is of a size to engage the inner periphery of the housing 8. The packer 58 may be secured on the middle plug 32 in any desired manner, such as by a retaining ring 60 telescoped over the lower end of the middle plug and held in position by a lower ring 62 threadedly secured on the lower end of the middle plug. A plurality of ports 64 extend transversely through the lower ring 62 into communication with an annular space 65 between the plug 32 and a portion of the upper ring 60. The space 65 in turn communicates with a plurality of passageways 66 extending vertically through the middle plug 32. Thus, communication is established between the top of the middle plug 32 and the annular chamber 68 formed below the packer 58 between the pump cylinder 34 and the housing 8.

The vertical passageways 66 are formed in circumferentially spaced relation around the bore 42 of the middle plug, as shown in Fig. 2, and communicate at their upper ends with an annular chamber 70- formed around the motor cylinder 28 by a jacket 72. The jacket 72 is secured at its lower end to the middle plug 32 and at its upper end to a tubular shaped head 74. The head 74 is in turn threadedly secured to the lower end of the macaroni or power tubing 76. A slotted member 78 is secured on the upper end of the motor cylinder 28 to engage the upper end of the jacket 72 and maintain the motor cylinder 28 in alignment with the jacket. However, the member 78 permits the flow of high pres sure fluid from the power tubing 76 downwardly into the annular chamber 70. It will the chamber 70 surrounds the inlet ports 80 in the lower end portion of the motor cylinder 28 to continuously direct high pressure power fluid into the lower portion of the cylinder 28 as previously indicated.

Operation The large tubing 4, with the collar 6, housing 8 and seating nipple it) suspended therefrom, is inserted in the well bore and may be considered a part of the permanent well installation. In fact, many wells formerly produced by use of sucker rod type of pump will have a tubing assembly similar to that shown herein. In this event, the tubing installation will already be in place when it is' desired to utilize my novel pumping unit 24. Before running the pumping unit 24, however, the seating shoe and standing valve assembly 16 is lowered through the large tubing 4 and seated in the seating nipple in the manner shown in Fig. 1. This assembly 16 may be' easily lowered by means of a wire line (not shown) in a manner well: known in the art.

also be observed that 'This fluid will then,

rounding the pump 36.

The pumping unit 24 is then' assembled as shown in Fig. 1 and secured on the lower end of the power tubing 7 76; whereupon, the unit 24 is lowered through the large tubing 4. The power tubing 76 is lengthened by adding joints at the top of the well until the. seat 46 engages the upper bore 48 of the seating shoe assembly 16. At this time the packer 58 will be in engagement with the inner periphery of the housing 8 at the upper end of the housing. In the final seating movement of the pumping unit 24,. the weight of the string of power tubing 76 is imposed on the unit 24 to wedge. the seat 46 in the tapered bore 48 and the packer 58 into the upper end of the housing 8. Upon seating of the unit 24, at least a portion of the weight of the power tubing 76 is imposed on the unit 24 to retain the unit 24 in its seated position, as will be more fully hereinafter set forth.

Power fluid is then supplied to the upper end of the power tubing 76 by any suitable pumping mechanism (not shown) at the top of the well. The power fluid flows downwardly through the tubing 76 and through the slots in the member 78 into the annular chamber 70 surrounding the motor cylinder 28. A portion of the power fluid then flows through the inlet ports 80 into the lower end portion of the motor cylinder 28 to reciprocate the motor piston assembly 30. The rod 40 transmits the motion of the piston assembly 30 to the pump piston assembly 38 to pick up well fluid through the lower standing valve 20 and force the well fluid upwardly through the bore 42 in the middle plug 32 and out through the ports 56 into the annulus between the jacket 72 and tubing 4. of course, be forced on upwardly through the tubing 4 toward the surface. Simultaneously, and as previously indicated, power fluid will be exhausing from the motor cylinder 28 downwardly through the hollow connecting rod 40 into the upper end of the pump cylinder 34 to join with the well fluid being pumped.

While high pressure power fluid is being introduced through the ports 80 into the motor 26, a portion of the power fluid is also directed through the vertical passageways 66 in the middle plug 32, the space 65, and out through the ports 64 into the annular chamber 68 sur- It will be observed that the outer diameter of the packer 58 is larger than the outer diameter of the seat 46 on the lower end of the pump, therefore, the high pressure fluid in the annular chamber 68 will constantly urge the pumping unit 24 upwardly in a direction to remove the seat 46 from the upper end 18 of the seating shoe assembly 16. However, the weight of the power tubing string 76 being imposed on the pumping unit 24 will be greater than this hydraulic force to retain the pumping unit in its seated position during normal operation.

When it is desired to remove the pumping unit 24, the power tubing 76 is raised at the surface until most, if not all, of the weight of the power tubing 76 is removed from the pumping unit 24. Power fluid may be either continuously supplied through the power tubing 76 during and after the lifting of the power tubing, or discontinued during the raising of the power tubing and then restarted to impose the pressure of the power fluid in the annular chamber 68'surround-i ng the pump 36. When the weight of the power tubing 76 has been removed, the hydraulic pressure acting on the lower end of the packer 58 and the downwardly facing portions of the pump cylinder 36 will be sufficient to raise the pumping unit 24- and remove the seat 46 from the seating shoe assembly 16. When the seat 46 has been raised, the high pressure fluid will be directed on downwardly into the assembly 16- to close the lower standing valve 20. At this time the high pressure fluid will be acting on the entire lower end of the pump 36, as well as the lower end: of the packer '58. Thus, the pumping unit 24 will be raisedthrough the housing'8 and the large tubing 4.

In the type of installation shown, Where the housing 8 is smaller in diameter than the tubing string 4, the hydraulic force raising the pumping unit 24 will be effective only until the packer 58 is raised above the housing 8. At this time, the power tubing 76 is pulled upwardly in the normal manner to remove the pumping unit '24 from the well.

As previously indicated, and as will be apparent to those skilled in the art, it is desirable that the power tubing 76 be made out of a light-weight material and as small as possible to provide an economical pump installa tion. In the present assembly, the power tubing '76 need be made only strong enough to withstand a pressure differential between the power fluid pressure and the hydrostatic pressure of the well fluid being pumped through the large tubing 4, as well as being strong enough to pick up its own weight. The weight of the pumping unit 24 will be small, compared with the total weight of the power tubing 76, to provide a negligible increase in weight which the power tubing 76 must support during installation and removal of the pumping unit 24.

From the foregoing it will be apparent that the present invention provides a novel fluid operated pump assembly which may be easily installed and removed from a well. The pumping unit is unseatcd by hydraulic pressure derived from the power fluid normally used in operating the pumping unit. Thus, the power tubing it not used for unseating the pump and may be made out of minimum strength material. The pumping unit may be conveniently installed in an existing sucker rod type pump installation to facilitate the conversion of a well from a sucker rod to a hydraulic pump. It will also oe observed that the unseating hydraulic pressure is applied to the pumping unit without the necessity of reversing the flow of fluid through the power and production tubing strings, as in the usual free pump type of installation.

Changes may be made in the combination and arrange ment of parts or elements heretofore set forth in the specification and shown in the drawings, it being understood that changes may be made in the precise embodiment shown without departing from'the spirit and scope of the invention as defined in the following claims.

I claim:

1. A subsurface well pump assembly, comprising a first string of pipe extending downwardly into the well, a tapered seating nipple on the lower end of the first string of pipe, a seating shoe and standing valve assembly in the seating nipple, an elongated fluid operated pumping unit inserted in the first string of pipe and having an exhaust port therein in upwardly spaced relation from the lower end of the unit, a seat on the lower end of the unit engaging the seating shoe, a packer around the unit between the lower end thereof and said exhaust port engaging the inner periphery of the first string of pipe and forming an annular chamber around the unit between said seat and packer, said packer having an outer diameter greater than the outer diameter of said seat, a supply of high pressure fluid at the top of the well, a second string of pipe extending from the high pressure fluid supply downwardly through the well and communicating with the pumping unit to supply high pressure power fluid to the pumping unit, and means for directing high pressure fluid from the second string of pipe into said chamber for unseating the pumping unit.

2. A pump assembly as defined in claim 1 characterized further in that the second string of pipe is positioned in the first string of pipe and connected to the upper end of the pumping unit.

3. A pump assembly as defined in claim 2 characterized further in that said means comprises passageways through the pumping unit.

4. A subsurface well pump assembly, comprising a first string of pipe extending downwardly in the well,

a seating nipple on the lower end of the first string of pipe, a seating shoe and standing valve assembly in the seating nipple, a pump inserted in the first string of pipe and having a seat on the lower end thereof of a size to engage the seating shoe, said pump having an inlet through the seat and a discharge at its upper end, a tubular mid dle plug connected to the upper end of the pump and having a discharge port therein communicating with the pump discharge, a packer around the middle plug below said discharge port of a size to engage the inner periphery oi the first string of pipe and form the upper end of a chamber around the pump, the outer diameter of said packer being larger than the outer diameter of the seat on the pump, a fluid motor secured on the upper end of the middle plug and having an inlet for high pressure power fluid, a connecting rod extending from the motor to the pump through the middle plug, a supply of high pressure iiuid at the top of the well, a second string of pipe extending from said supply downwardly through the well into communication with the motor inlet to supply high pressure power fluid to the motor, and means for directing a portion of the high pressure fluid from the second string of pipe to the chamber around the pump.

5. A pump assembly as defined in claim 4 characterized further in that said second string of pipe is smaller than said first string of pipe and is positioned within said first string of pipe.

6. A pump assembly as defined in claim 5 characterized further in that said means comprises at least one passageway through the middle plug extending from below said packer into communication with the motor inlet.

7. A subsurface well pump assembly, comprising a string of large pipe extending downwardly into the well, a tapered seating nipple secured on the lower end of the large pipe, a seating shoe and standing valve assembly in the seating nipple, a pump cylinder inserted in the large pipe and having a seat on the lower end thereof of a size to engage the seating shoe, a motor cylinder in the large pipe above the pump cylinder and having inlet ports therein, a tubular middle plug connected to the adjacent ends of the pump and motor cylinders and having an exhaust port therein communicating with the upper end of the pump cylinder, a packer around the middle plug below the exhaust port engaging the inner periphery of the large pipe and forming an annular chamber around the pump cylinder between said packer and seat, said packer having an outer diameter larger than the outer diameter of the seat on the lower end of the pump cylinder, a fluid motor assembly in the motor cylinder, a pump piston assembly in the pump cylinder, 9. rod extending through the tubular middle plug and connected at its opposite ends to the motor assembly and pump piston, a jacket surrounding the motor cylinder and connected at its lower end to the middle plug to form an inlet chamber communicating with said inlet ports, a supply of high pressure fluid at the top of the well, a string of small pipe extending from said supply downwardly through the large pipe, the lower end of the small pipe being connected to the top of the jacket surrounding the motor cylinder to direct high pressure power fluid into said inlet chamber, and means for directing a portion of the high pressure fluid into the chamber around the pump cylinder.

8. A pump assembly as defined in claim 7 characterized further in that said means comprises at least one passageway extending through the middle plug from said inlet chamber to the chamber around the pump cylinder.

References Cited in the file of this patent UNITED STATES PATENTS

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