US2720839A

US2720839A - Rodless pump setting

Info

Publication number: US2720839A
Application number: US312493A
Authority: US
Inventors: Roy L Chenault
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1952-10-01
Filing date: 1952-10-01
Publication date: 1955-10-18
Anticipated expiration: 1972-10-18

Description

United States Patent Ofiice 2,720,839 Patented Oct. 18, 1955 RODLESS PUMP SETTING Roy L. Chenault, Seneca, Pa., assignor to United States Steel Corporation, a corporation of New Jersey Application October 1, 1952, Serial No..312,493 Claims. (Cl. 103-46) This invention relates to an improved setting for hydraulically operated subsurface pumps used in oil wells and the like and commonly known as rodless pumps.

Essentially a rodless pump comprises'a hydraulic motor and reciprocating pump assembly seated near the bottom of a well. The motor is mechanically connected to'the reciprocating element of the pump and is powered by a stream of oil pumped down the well from the surface. In many constructions the motor-pump assembly is attached to the well tubing; to remove it for maintenance or repair it is necessary also to pull the tubing. In other constructions the motor-pump assembly is free of the tubing and can be removed by pumping oil down the well in the reverse direction. The latter arrangement facilitates removal of the assembly, but has disadvantages that .the pump must be equipped with one additional standing valve, which increases the flow resistance, and also that a rather elaborate catcher mechanism is required for receiving the assembly at the surface.

In a third arrangement the motor-pump assembly is free of the tubing and is adapted to be withdrawn by a wire line and fishing tool run into the well and latched to the top of the assembly. This last arrangementdoes not require the additional standing valve nor the catcher mechanism, but those with which I am familiar lack means for initially unseating the assembly and for draining the tubing of oil. Consequently it has been necessary to exert sufiicient pull on the wire line first to unseat'the assembly and then to draw it upwardly through the resistance of the oil in the tubing.

The present invention relates to rodless pumps of the last described type, and one object is to provide an improved setting which enables the static head of oil inthe tubing initially to unseat the motor-pump assembly and which drains the tubing before the assembly is withdrawn, thereby facilitating the withdrawal operation.

A further object is to provide an improved rodless pump setting which includes a normally closed bleeder valve situated in the tubing near the top of the motorpump assembly and adapted to be opened by the fishing tool for draining the tubing through which the assembly subsequently is withdrawn.

A further object is to provide an improved rodless pump setting which includes a valve for draining the tubing through which the motor-pump assembly is withdrawn and in which the static head of oil in an adjacent tubing automatically acts to unseat the assembly as the first tubing drains. I

In accomplishing these and other objects of the invention, I have provided improved details of structure, ,a preferred form of which is shownin the accompanying drawing, in which: I

Figure 1 is a somewhat schematic vertical sectional view of a pump setting which embodies features .of the present invention;

Figure 2 is a vertical sectional view on a larger scale of the bleeder valve; and j j tubing 12 and to the surface.

Figure 3 is a side elevational view partly broken away of the fishing tool used to withdraw the pump from the setting shown in Figure 1.

Figure 1 shows somewhat schematically a rodless pump installation which comprises a first tubing 10 and a second parallel tubing 12. The first tubing 10 includes a special coupling 13, hereinafter described in more detail, joined to the bottom of its lowermost tube section. A spacer nipple 14 'is joined to the'lower end of the coupling 13 and carries anothercoupling 15 at its lower end. Another spacer nipple 16 is joined to the coupling 15 and at its lower end carries a cross-over coupling 17. The tubing 12 also is connected into the coupling 17, which contains a transverse passage 18 furnishing communication therewith. The borethrough coupling 15 is of larger diameter than that through the cross-over coupling 17. If desired, the lower end of the latter coupling can carry alower nipple 19.

A hydraulic motor-pump assembly 20 is received within the bores of the spacer nipple 14, the coupling 15, the spacer nipple 16, the cross-over coupling 17, and terminates within the lower nipple 19. The exterior of the motor-pump assembly 20 carries a packing ring 21, preferably of the O-type, which seats in the bore of the coupling 15,, and a second packing ring 22, which is spaced below the first such ring and is of smaller outside diameter and seats within the bore of the cross-over coupling 17 below its transverse passage 18. 'The inside faces 'of the

couplings

15 and 17 thus furnish upper and lower spaced apart seatingareas for the assembly. The upperend of the assembly carries a strainer 23, which in turncarries a fishing neck 24 at its upper end. The motor of the assembly 20 is powered by a stream of oil pumped down the tubing 10 and through the strainer 23. The exhaust power oil from the motor and the oil pumped from the well blend and discharge from openings 25 in the assembly wall intermediate the upper and lower seating areas, whence they flow through the transverse passage 18, into the The motor and pump per se are not part of the present invention, but can be of any standard or desired construction and thereforeare not shown in detail. Reference may be made to my Patent No. 2,191,369, dated February 20, 1940, for a showing of one suitable form of motor and pump. The pump should be of a type which does not allow backward flow therethrough, and pumps which normally would allow such flow can'be equipped with a special check valve to permit their use in the setting of the present invention.

The special coupling 13 carries a normally closed bleeder valve 26. As best shown in the larger scale view of Figure 2, this coupling contains a transverse passage 27 and an integral valve seat28 formed adjacent the inner end of said passage. 'A piston 29 is mounted for sliding movement within the passage 27 and has a shoulder near its inner end adapted to engage the seat 28 for closing the passage. Beyond said shoulder the piston carries an operating plunger 30 which extends into the bore of the coupling. A plug 31 closes the outer end of the passage 27, and a spring 32 bears between plug 31 and the back of the piston 29 to hold the piston seatedagainst its seat 28. In addition the coupling has a duct 33 which extends from its bore into its transverse passage 27 behind the piston 29. This duct transmits hydraulic pressure from the tubing 10 to the back of the piston to provide a net hydraulic force which cooperates with the spring in holding the piston seated. The coupling also contains a bleeder passage 34 which preferably has a constriction or choke 35 near its discharge end. As long as the piston 29 is seated, the bleeder passage is closed off from the tubing 10.

Figure 3 shows a combined weight bar and fishing tool 36 which can be run into the tubing 10 on a wire line 37,

V .As the tubing ing tool descends, it abuts theplunger fii) of the bleeder valve 26 andmechanically unseats the piston 29 from the seat 28. When the valve thus opens, oil from the tubing ,10 drains 'through the

passages

27 and 34 and the choke 35. Thepurpose of the choke is to limit the velocity of flow through thevalve and to absorb the greaterpart of the pressure drop and thus avoid wear on the seating portion .of the piston 29 and the seat28.

V 10 drains, the pressure which the oil therein exerts on the top of the motor-pump assembly 20 of course din'iinishes The static head of the oil in the tubing 12 remains, since oil cannot flow backward through the pump, The force frorn this static head is Lapplied to the interior of the spacer nipple 16 and acts upwardly against the packing ring 21 and also downwardly againstthe packing ring 22. Since the diameter and also the. effective area of the former are greater, the net force of this static head tends to raise the motor-pump assembly. The assemblyunseats when thetubing ltl drains l .suificiently that its pressure is overcome by this'net force.

lffor any reasonthe static head is insuflicient tounseat the assembly, additional pressure can be applied'to the tubing 12 at the surface. 7 p v a, Preferably the lower part of the tubing 12 contains a check valve 39 and a restricted by-pass 40. The check valve allows unrestricted flow of oil up the tubing but allows flow downwardly only via the by-pass. This arrangement prevents a sudden rush of fluid from the tubing '12 after the motor-pump assembly is unseated. A rush of fluid might tend to drive the motor-pump assembly up the tubing 10 ata high velocity or else'cause it to chatter by forcing itjback into the coupling 17 after it hasbecome unseated. V 7

After the combined weight bar and fishing tool 36 opens the bleeder valve 26, its socket 38 receives the fishing neck 24 andjlatches into engagementtherewith. When the tubing 10 has drained and the motor-pump assembly has unseated, the wire line 37 is reeled in and the assembly thus brought to the surface. Since the wire line furnishes support for the assembly, no catcher mechanis m is needed. The tubing 12 also; drains via the bypass 40 and thus both tubings are flushed when the assemblyf is withdrawn. V i

The motor-pump assembly can beinstalled simply by lowering it with the wire line and releasable fishing socket. As it is lowered to its working position, the -typepack- 'ing ring 21 first enters thecoupling 15 and immediately thereafter the packing ring 22 enters th'e seating bore of "the cross-over coupling 17. An O-ring is especially desirable for use in the coupling 15 inasmuch as'it has low frictional resistance and readily enters the bore with only the weight of the assembly to force it. The lower packing ring 22 next can be forced into position by applying hydraulic pressure to the tubing whichpressure acts on the top-of the assembly'Zil- .From the foregoing description it is seen that the present invention afiords'a rodless pump setting which enables the motor-pump assembly to be withdrawn with a wire line with its attendant advantages. At the same time the invention provides hydraulic means for initially unsea ting the assembly and drains the tubing through which the assembly is withdrawn, thereby eliminating the need for excessive forces to be applied to thewire line.

While I have'shown and described only a single embodiment of the invention, it is apparent that modifications may-arise. Therefore I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

.I claim: 1

1. A rodless pump setting comprising a pair of parallel tubings; the first 'ofwhich is adapted to transniitfiuid downwardly and the second of which is adapted to trans- 0 adapted to seat a motor-pump assembly, meansrumisnin communication between the lower parts of said tubings, a normally closed outwardly opening bleeder valve in said first tubing adjacent but above its seating areas and operating means for said valve projecting into said first tubing and adapted to open the valve outwardly under mechanical pressure applied within the first tubing, said second tubing by-passing said valve.

2. A setting as definedinclaim 1 in which theareas adapted to seat a motor-pump assembly are two in number s and are vertically spaced apart, and the means furnishing communication between said tubings enters said first tub ing intermediate said areas. I

3. A setting as defined in claim 2' in which the upper seating area is of greater diameter area..

tubings, the first of which isadapted to transmit fluid downwardly and the second .of which is adapted to transmit fluid upwardly, a special coupling joined-to the lower end of said first tubing, a spacer n pple joined at its upper end to said special coupling, .a second coupling joined to a but above said seating areas, and operating means for said" valve projecting into the bore of said special coupling and adapted to open the valve outwardly under mechanical pressure applied within the first tubing; said second tubing by-passing said valve.

5. A setting as defined in claim 4 in which said upper seating area is of greater diameter than said lower seating area.

6. A setting as defined in claim 4 in which said special coupling has a transverse passage which contains a seat for said bleeder valve, a duct communicating between its bore and the outer portion of its transverse passage, and a bleeder passage extending from its transverse passage to the outside, said bleeder valve includes a piston slidably mounted in said transverse passage and a spring which in cooperation with pressure transmitted via said duct normally holds said piston'in engagement with said seat, Y includes a plunger fined to the i and said operating means inner end of said piston;

7. A setting as defined in passage has a restricted choke."

8. A setting as defined in claim 4.in which the lower portion of said second tubing contains a check valve which permits upward flow of fluid only and'a restricted by-pass for downward flow of fluid. a

9. A rodless pump installation comprising a pair of parallel tubings,

upper and lower spaced apart areasin saidfirst tubing'and having its discharge intermediate the seatingareas, means 7 furnishing communication between said tubings and being joined to said first tubing intermediate the seating areas, a

normally closed outwardly opening bleeder valve in said 7 first tubing adjacent but above its upper seating area, o

erating'means for said bleeder valve projecting into said the valve outwardly under through said first tubing, said second tubing by-passing.

said valve.

than the lower seating 4. A rodless pump setting comprising a pair of parallel coupling.

aria 6 injwhichsaidbleeder the first of which is adaptedto transmit fluid downwardlyand the second of which is adapted to transmit fluid upwardly, a motor-pump assembly seated at.

10. An installation as defined in claim 9 in which the upper seating area is of greater diameter than the lower seating area so that static pressure applied to the space within said tubing between said seating areas exerts a net upward force on said assembly.

References Cited in the file of this patent