GB2101217A - Jet pump for oil wells - Google Patents

Abstract

A fluid operated pump system which includes power fluid supply means comprising either the annulus 36 between well casing 12 and production tubing 18, or a secondary tubing 38, and a production tubing, set in a well, the production tubing having a housing 40 at the lower end with which the power fluid supply means communicates. A pump unit, including a fluid operated pump 10, is movable downwardly through the production tubing into the housing. The pump is operable in the housing by operating fluid under pressure supplied through the power fluid supply means to pump fluid from the well into the production tubing. A sealed cavity 42 is provided at the lower end of the pump. The sealed cavity communicates with the power fluid supply means and with the fluid operated pump and is provided with lands 46 thereon which balance the hydraulic forces to maintain the pump in place in the housing during production. The pump unit operates in a balanced pressure area and does not need latch means to stay in place. <IMAGE>

Description

SPECIFICATION Improved jet pump for oil wells Background of the Invention The present invention relates in general to fluidoperated oil well pumping systems of the type wherein a pump unit which includes a fluid operated pump is circulated into and out of its operating position in a well. More particularly, the invention relates to an open system wherein the production fluid discharged by the pump and the spent operating fluid discharged thereby are mixed together and conducted to the surface through a common, production tubing. Operating fluid under pressure for actuating the fluid operated pump is delivered thereto through a parallel supply conduit, or through the annulus between the well casing and the production tubing.

Still more specifically, the present invention contemplates a fluid operated pump system which is of the reverse circulation type wherein the pump is circulated into and out of the well through a production tubing which is relatively large, and wherein the operating fluid is delivered to the pump through a parallel supply tubing which is relatively small or through the annulus between the well casing and the production tubing. Such a reverse circulation system has the advantage of minimizing fluid friction since the combined flow of production fluid and spent operating fluid is conducted to the surface through the larger production tubing, the smaller flow of operating fluid under pressure being conducted downwardly to the pump through the smaller supply tubing or through the annulus.

With such a reverse circulation system, prior art pump units are normally run in by introducing fluid under pressure into the production tubing thereabove, and the pump unit is circulated out by introducing fluid under pressure there beneath through the return conduit. Since the supply conduit contains operating fluid under high pressure during normal operation of the fluid operated pump when the pump unit is in its housing at the lower end of the production tubing, latch means are provided for preventing upward circulation of the pump unit through the production tubing of the pump unit during normal operation of the fluid operated pump.

Prior art attempts to improve upon fluid operated pump systems of the reverse circulation type have always seemed to require the use of a complicated latch means. U.S. Patent No.

2,869,470, granted January 20, 1959 to Clarence J. Coberly, is exemplary of patents disclosing latch means for latching the pump unit in its operating position against the upward bias resulting from the application of the operating fluid under pressure in the supply tubing to the lower end of the pump unit. After the pump unit arrives in its operating position in the housing at the lower end of the production tubing, the latch means is set by gradually building up the operating fluid pressure in the supply conduit, frictional resistance being sufficient to prevent upward displacement of the pump unit before the latch means is set as long as the operating fluid pressure is increased slowly. When it is desired to circulate the pump unit out through the production tubing, the latch means is released by increasing the pressure in the production tubing.The Coberly pump unit can be latched and unlatched hydraulically by selective pressure applications to the latch means. However, malfunctioning of the hydraulically operated latch means makes it extremely difficult to set or release the pump unit.

If the pump unit cannot be latched in its operating position, it must be circulated out and repaired or replaced. On the other hand, if the latch means cannot be released, due to the effects of corrosion, sand accumulations, or the like, it may be necessary to pull the entire tubing system.

U.S. Patent No. 3,687,573, granted August 29, 1972 to Ralph F. McArthur, et al is an example of prior art attempts to provide a mechanically actuated latch means as opposed to the Coberly hydraulically actuated latch means.

Summary of the Invention The present invention provides an improved fluid operated pump system of the open type which provides a retrievable jet pump which does not require latch means or hold down devices to maintain the pump unit from upward circulation through the production tubing during normal operation of the fluid operated pump.

According to the present invention a sealed cavity is provided at the lower end of the pump unit. The sealed cavity communicates with the power fluid supply means and with the fluid operated pump. The sealed cavity is provided with lands thereon which balance the hydraulic forces to maintain the pump unit in place in the housing during production. In operation, the pump unit operates in a balanced pressure area and does not need latch means to stay in place.

According to the present invention, the power fluid supply means may comprise either secondary tubing or the annulus between well casing and production tubing.

Since jet pumps operate inefficiently returning fluids in a small tubing string because of added discharge pressure, primary or production returning fluids are usually returned in the annulus between the well casing and tubing. However, off shore production practices prohibit production flowing against the casing because of corrosion, etc. The present invention solves this problem by conducting treated power fluid down the annulus, or ary tubing, returning the combined spent power fluid and production up the primary tubing.

Brief Description of the Drawings FIG. 1 comprises a semi-diagrammatic view of a fluid operated well pump of the jet type incorporating the improvements of the present invention.

FIGS. 2A and 2B show a fragmentary, longitudinal cross sectional view of the jet pump of the present invention illustrating the nozzle, throat and defuser thereof.

FIG. 2C shows how FIGS. 2A and 2B interrelate.

FIG. 3 is a cross sectional view taken on the line 3-3 of FIG. 2A.

FIG. 4 is a cross sectional view taken on the line 4-4 of FIG. 2B.

Description of the Preferred Embodiment In most installations, a packer (not shown) is set below the pump, but above the perforations effecting a seal between the supply tubing and the casing. The mixture of spent power fluid and pumped well fluid is then returned upwardly to the surface in the annulus between the well tubing and the casing. However, as previously indicated, off shore production practices prohibit production flowing against the casing because of corrosion, etc. Alternatively, a reverse flow circulation can satisfy this restriction by flowing treated power fluid in the annulus between casing and return mixed produced fluids in the primary tubing to the wellhead.The latter alternative is shown in FIG. 1 which illustrates a well pump 10 of the jet type in a casing 12 provided at its upper end with a casing head 14 which supports the production and the supply tubings 1 8 and 16, respectively.

The supply tubing 1 6 conveys operating or power fluid, such as, for example, clean crude oil, downwardly under pressure into the well to the pump 10. The production tubing 1 8 conveys a mixture of spent power fluid and pumped well fluid or production fluid upwardly to the surface.

As can be seen, the upper and lower ends 1 Oa and 1 Ob, respectively, of the pump 10 are oriented generally vertically in a housing 40 at the lower end of the production tubing 1 8 in the well casing 12, with the upper end 1 Oa thereof uppermost when the pump 10 is in its operating position in the well casing 1 2. The pump 10 is provided with an intake 20 at the lower end 1 Ob thereof for the operating or power fluid under pressure, with an inlet 22 for the well fluid, and with an outlet 24 at the end 1 Oa for the combination of fluid produced by the well and spent operating or power fluid.

Nozzle or jet means 26, which is directed upwardly when the pump 10 is in its operating position in the well casing 12, communicate through the passages 27 and 28 with the intake 20 and the outlet 24, respectively, and discharge into the throat 30, then through the defuser 32 and into the outlet 24 leading to the production tubing 1 8.

As can best be seen in FIGS. 1 and 2B, fluid from the well is brought upward from the inlet 22 in a generally vertical direction through the passages 31 connecting the inlet 22 to the nozzle or jet means 26, avoiding a reversal of direction, and entrained in the high velocity jet stream of operating or power fluid emerging from the nozzle or jet means 26. The combined fluids are carried into the throat 30, and then into the defuser 32, and the combination of fluids are pumped upward in a generally vertical direction through the passage 28 connecting the defuser 32 to the outlet 24 by the energy imparted by the operating fluid emerging from the nozzle 26. The throat 30 is provided with a generally constant bore section.

The power fluid supply means may comprise the annulus 36 between the well casing 12 and the production tubing 18, or it may comprise a secondary tubing 38 shown in dashed lines. The production tubing 1 8 is provided with a housing 40 at the lower end thereof with which the power fluid supply means, either through the annulus 36 or the secondary tubing 38, communicates.

The pump unit, including a fluid operated pump 10, is movable downwardly through the production tubing 18 into the housing 40. The pump is operable in the housing 40 by operating fluid under pressure supplied through the power supply means to pump fluid from the well into the production tubing 1 8.

A sealed cavity 42 is provided at the lower or downwardly facing end 1 Ob of the pump 10. The cavity 42 communicates with the power fluid inlet 20 and with the passage 27 leading to the jet means 26. The cavity 42 is sealed by means of the teflon seals 44 on either side thereof. The cavity 42 is provided with lands 46 thereon which balance the hydraulic forces to maintain the fluid operated pump 10 in place in the housing 40 during production.

It will, of course, be understood that during operation the supply and production tubing 16 and 18, respectively, are connected at their upper ends to a valve head 48. The valve head 48 is provided with valve means (not shown) controlled by handle 50 for diverting operating or power fluid under pressure, which is supplied to the valve head 48 through a line 52 by a pump 54, into either the supply tubing 1 6 or the production tubing 1 8. Normally, when the well pump 10 is in operation as hereinbefore described, the handle 50 is positioned so that valve means in the valve head 48 delivers the operating or power fluid under pressure into the supply tubing 16, and then either through the annulus 36 between the well casing 12 and the production tubing 18, or through the secondary tubing 38, to operate the well pump 10.The pump 10 may be operational in or removed from the housing 40 of the production tubing 1 8 in the well casing 12 by means of a retrieving tool which circulates the pump 10 into and out of its desired position.

As previously indicated herein, normal hydraulic installations conduct power fluid down the primary tubing and return power fluid and production up the annulus or a secondary tubing string. Jet pumps operate inefficiently returning fluids in a small tubing string because of added discharge pressure, usually returning fluids in the annulus between the well casing and the production tubing. Offshore production practices prohibit production flowing against the casing because of corrosion, etc. The present invention conducts the treated power fluid down the annulus 36, or secondary tubing 38, returning the production fluid and spent power fluid up to the primary tubing 1 8.

The present invention provides a retrievable jet pump 10 wherein controlled power fluid is against the well casing 1 2. Gas will lighten the return fluid. The pump 10 of the present invention may be utilized with simple equipment for production test. Furthermore, drilling pumps can be used for power. An intake pressure recorder can also be utilized.

The pump unit 10 of the present invention does not require latch means to stay in place. Since controlled power fluid is supplied through the inlet 20 into the cavity 42 between the two seals 44, with the cavity 42 being provided with the lands 46, the hydraulic forces are balanced and the net force is downward because of greater discharge than intake pressure.

It will be understood that various changes, modifications and substitutions may be incorporated in the particular embodiments of the invention herein disclosed without departing from the spirit of the invention and defined by the claims which follow.

Claims (8)

1. In a fluid-operated pump system of the open type wherein the production fluid discharged by the pump and spent operating fluid discharged thereby are mixed together and conducted to the surface through a common production tubing, the combination of: a) power fluid supply means comprising one of the annulus between well casing and production tubing and a secondary tubing, and a production tubing, set in a well, said production tubing having a housing at the lower end thereof with which said power fluid supply means communicates; b) a pump unit, including a fluid operated pump, movable downwardly through said production tubing into said housing, said pump being operable in said housing by operating fluid under pressure supplied through said power fluid supply means to pump fluid from the well into said production tubing; and c) a sealed cavity at the lower end of said pump, said selaed cavity communicating with said power fluid supply means and with said fluid operating pump and being provided with lands thereon which balance the hydraulic forces to maintain said fluid operated pump in place in said housing during production.

whereby said pump unit operates in a balanced pressure area and does not need latch means to stay in place.

2. The pump system according to claim 1, wherein said power fluid supply means comprises secondary tubing.

3. The pump system according to claim 1, wherein said power fluid supply means comprises the annulus between said well casing and production tubing.

4. In a fluid-operated free pump system, the combination of: a) power fluid supply means comprising one of the annulus between well casing and production tubing and a secondary tubing, and a production tubing, set in a well, said production tubing having a housing at the lower end thereof with which said power fluid supply means communicates; b) a pump unit, including a fluid operating pump, movable downwardly through said production tubing into said housing, said pump being operable in said housing by operating fluid under pressure supplied through said power fluid supply means to pump fluid from the well into said production tubing; and c) a sealed cavity at the lower end of said pump, said sealed cavity communicating with said power fluid supply means and with said fluid operated pump and being provided with lands thereon which balance the hydraulic forces to maintain said fluid operated pump in place in said housing during production; whereby said pump unit operates in a balanced pressure area and does not need latch means to stay in place.

5. The pump system according to claim 4, wherein said power fluid supply means comprises secondary tubing.

6. The pump system according to claim 4, wherein said power fluid supply means comprises the annulus between said well casing and production tubing.

7. In a fluid-operating free pump system, the combination of: supply and production tubings set in a well and connected at their lower ends to a housing; a fluid operated free pump unit movable downwardly through said production tubing into said housing and operable in said housing by operating fluid under pressure from said supply tubing to discharge production fluid into said production tubing; and a sealed cavity at the lower end of said pump, said sealed cavity communicating with said supply tubing and with said fluid operated pump and being provided with lands thereon which balance the hydraulic forces to maintain said fluid operated pump in place in said housing during production, whereby said pump operates in a balanced pressure area and does not need latch means to stay in place.

8. A fluid operated pump system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.