Patent Description:
A variety of pumps are used in oil producing wells to pump well fluid to a wellhead assembly at an upper end of the well. The well fluid often comprises water, oil and gas. Typical pumps include rotary pumps, such as centrifugal or progressing cavity types, or they may be reciprocal pumps having a plunger that strokes upward and downward within a polished bore of a barrel or housing. The pump may be electrically driven by a downhole motor or, in the case of reciprocal pumps, stroked by a string of rods extending downward from the wellhead assembly.

Rod driven reciprocal pumps have concerns, such as rod tubing wear and system lower efficiency due to the extension and retraction of the rod string. Also surface environmental problems may occur at the stuffing box of the wellhead assembly.

Reciprocal well pumps powered by a surface hydraulic pump are also known. Normally, the hydraulic fluid pressure will be supplied from the surface down one or more hydraulic lines that extend alongside production tubing. Retrieving the reciprocal pump for maintenance and repair normally requires pulling the tubing and the hydraulic line. <CIT> discloses a pump according to the state of the art with a centrally arranged hydraulic line.

A well pump assembly comprises a tubular receptacle for attachment to a lower end of a string of production tubing. A docking station mounts to the receptacle, the docking station having a lower well fluid conduit for receiving well fluid from the well, a lower orientation guide, and a lower hydraulic connector. A hydraulic line extends alongside the receptacle and is in fluid communication with the lower hydraulic connector for supplying hydraulic fluid. A hydraulically actuated pump is configured to be lowered into and retrieved from the receptacle. A guide member on a lower end of the pump has an upper well fluid conduit leading to a well fluid intake of the pump, an upper orientation guide, and an upper hydraulic connector in fluid communication with the pump. As the pump is being lowered into the receptacle, the upper well fluid conduit slides into sealing engagement with the lower well fluid conduit while the upper orientation guide engages the lower orientation guide and rotationally orients the upper hydraulic connector into stabbing engagement with the lower hydraulic connector to supply hydraulic fluid pressure from the hydraulic line to the pump.

A latching arrangement between the guide member and the docking station secures the pump on the docking station after the upper and lower hydraulic connectors have stabbed into sealing engagement with each other. An upward pull of sufficient force on the pump causes the latching arrangement to release, enabling the pump to be retrieved from the receptacle.

In the embodiment shown, the lower orientation guide comprises a lower sleeve surrounding the lower well fluid conduit, the lower sleeve having an upward facing oblique cam edge. The upper orientation guide comprises an upper sleeve surround the upper well fluid conduit, the upper sleeve having a downward facing oblique cam edge that engages the upward facing oblique cam edge as the guide member lands on the docking station.

An upstroke chamber within the pump receives hydraulic fluid pressure to power the pump. An upper hydraulic passage within a sidewall of the upper well fluid conduit has an open upper end in the upstroke chamber. The upper hydraulic connector is mounted to a lower end of the upper hydraulic passage. A lower hydraulic passage within a sidewall of the lower well fluid conduit has a lower end connected to the hydraulic line. The lower hydraulic connector is mounted to an upper end of the lower hydraulic passage.

The embodiment shown discloses means for preventing well fluid entry into the upper hydraulic connector prior to stabbing engagement of the upper hydraulic connector with the lower hydraulic connector. It also shows means for preventing well fluid entry into the lower hydraulic connector prior to stabbing engagement with of the lower hydraulic connector with the upper hydraulic connector.

The pump shown comprises a plunger with a plunger bore that reciprocates within a pump housing, defining an upward stroke chamber. The pump has a traveling valve mounted to the plunger for movement in unison to lift well fluid into the production tubing during an upstroke. The pump has a standing valve mounted to the pump housing to admit well fluid into the bore of the plunger during a down stroke.

A seal may be located between the pump and the receptacle. The receptacle has a closed bottom in the embodiment shown. The docking station is mounted to an upper side of the bottom. The lower well fluid conduit extends downward through the bottom.

The embodiment shown discloses a detent on the lower well fluid conduit. A latch sleeve surrounds the upper well fluid conduit. The latch sleeve has a rib that snaps into engagement with the detent when the upper well fluid conduit slides into engagement the lower well fluid conduit. An upward pull of sufficient force releases the latch sleeve from the detent to enable retrieval of the pump.

The method and system of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The method and system of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. In an embodiment, usage of the term "about" includes +/- <NUM>% of the cited magnitude. In an embodiment, usage of the term "substantially" includes +/- <NUM>% of the cited magnitude. The terms "upper" and "lower" and the like bare used only for convenience as the well pump may operate in positions other than vertical, including in horizontal sections of a well.

It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation.

Referring to <FIG>, a well has casing <NUM> cemented in place. A wellhead (not shown) at the upper end of the well supports a string of production tubing <NUM> in casing <NUM>. A tubular receptacle <NUM> secures by a coupling <NUM> to the lower end of tubing <NUM> and defines a closed lower end of tubing <NUM>. Receptacle <NUM> may be identical to other joints of tubing <NUM> except for having a closed lower end or bottom <NUM>. The closed lower end <NUM> of receptacle <NUM> supports a docking station <NUM>.

Docking station <NUM> has a lower conduit <NUM> that extends downward sealingly through closed lower end <NUM> of receptacle <NUM>. Docking station <NUM> has a lower orientation guide <NUM> located within the interior of receptacle <NUM>. The upper end of lower conduit <NUM> has one or more lower hydraulic fluid connectors <NUM> (only one shown). At least one hydraulic line <NUM> (two shown) extends from a hydraulic fluid supply pump <NUM> adjacent the wellhead down alongside tubing <NUM> to the lower end of receptacle <NUM>. Each hydraulic line <NUM> supplies hydraulic fluid pressure delivered by supply pump <NUM> to one of the lower hydraulic fluid connectors <NUM>.

The installation may have a downhole safety valve <NUM> located in lower conduit <NUM> below receptacle <NUM>. If so, a control line <NUM> extends from the wellhead alongside tubing <NUM> and receptacle <NUM> to safety valve <NUM>. Control line <NUM> controls safety valve <NUM> in one of several ways. For example, safety valve <NUM> may remain in an open position allowing upward well fluid flow through lower conduit <NUM> as long as hydraulic pressure remains in control line <NUM>. The lower end of lower conduit <NUM> extends below safety valve <NUM> sealingly through a polished bore of a packer <NUM>.

<FIG> shows a hydraulically actuated reciprocating pump <NUM> being lowered through tubing <NUM> for engagement with docking station <NUM>. A running tool <NUM> lowered on a running string <NUM> releasably engages an upper end of reciprocating pump <NUM>. Running string <NUM> would typically be either a wireline or coiled tubing. Running tool <NUM> may be a conventional tool that lowers and also retrieves equipment located in a well.

Reciprocating pump <NUM> may have an annular secondary seal member <NUM> on its exterior that will be in sealing engagement with the inner sidewall of receptacle <NUM> after landing. Annular seal member <NUM> could be an elastomer that swells in response to hydrocarbon in the well fluid. Alternately, it could be a cup seal that slides down the inner sidewall of tubing <NUM> during running. Or it could be a type that is energized by hydraulic fluid pressure supplied from a hydraulic line (not shown) extending to the wellhead. Annular seal member <NUM> helps prevent debris falling down production tubing <NUM> from accumulating on the bottom of receptacle <NUM>. Annular seal member <NUM> also provides support as a centralizer of the downhole equipment during installation and operation. Reciprocating pump <NUM> has an open upper end or outlet above annular seal <NUM> for discharging well fluid into tubing <NUM>.

An upper orientation guide member <NUM> secures to a lower end of reciprocating pump <NUM>. Guide member <NUM> has an upper conduit <NUM> for receiving well fluid and an upper orientation guide <NUM> for engaging lower guide <NUM>. While lowering reciprocating pump <NUM>, upper guide <NUM> will engage lower guide <NUM>, causing reciprocating pump <NUM> to rotate part of one turn and orient its hydraulic connector (not shown in <FIG>) with lower hydraulic connector <NUM>. Also, upper conduit <NUM> will stab into sealing engagement with lower conduit <NUM>. After lower hydraulic connector <NUM> is in engagement with the upper hydraulic connector, running tool <NUM> may be retrieved, leaving reciprocating pump <NUM> in receptacle <NUM>.

After annular seal <NUM> is in sealing engagement with the inner sidewall of receptacle <NUM>, a supply pump (not shown) adjacent the wellhead can supply hydraulic fluid pressure down hydraulic lines <NUM> to reciprocating pump <NUM>, causing it to operate. Well fluid flowing into the lower end of lower conduit <NUM> will enter upper conduit <NUM> and be pumped by reciprocating pump <NUM> into tubing <NUM> above annular seal <NUM>.

<FIG> illustrates more details of one embodiment of docking station <NUM>. Lower conduit <NUM> may have a bore with and upper bore portion 43a slightly larger in inner diameter than a lower bore portion 43b. Upper and lower bore portions 43a, 43b have a longitudinal axis <NUM>. A latching feature such as an annular recess <NUM> is formed in upper bore portion 43a. A lower hydraulic passage <NUM> extends through the sidewall of lower conduit <NUM> parallel with axis <NUM>. The upper end of hydraulic passage <NUM> joins lower hydraulic connector <NUM>. The lower end of hydraulic passage <NUM> extends laterally out the sidewall of lower conduit <NUM> and laterally through the sidewall of receptacle <NUM> to hydraulic line <NUM>. Lower guide <NUM> is a sleeve that receives and rigidly secures, such as by threads, to the exterior of lower conduit <NUM>. Lower guide <NUM> has an upward facing cam edge or surface <NUM> that may be in an oblique plane relative to axis <NUM>.

Reciprocating pump <NUM> has a well fluid intake member <NUM> on its lower end. Upper conduit <NUM> secures to and extends downward from pump intake member <NUM>. Pump intake member <NUM> may be considered to be a part of upper conduit <NUM>. An upper hydraulic passage <NUM> extends through the sidewall of pump intake member <NUM> parallel with axis <NUM>. Upper hydraulic passage <NUM> has a lower end at the lower end of pump intake <NUM>.

Upper guide <NUM> is a sleeve that rigidly secures, as by threads, to pump intake <NUM>. Upper guide <NUM> has downward facing upper cam edge or surface <NUM> that mates with lower cam surface <NUM>. Upper cam surface <NUM> may be identical to lower cam surface <NUM>. As upper guide <NUM> engages lower cam surface <NUM>, the inclination of cam surfaces <NUM>, <NUM> causes reciprocating pump <NUM> to orient and rotate less than one turn to axially align lower hydraulic connector <NUM> with an upper hydraulic connector at the lower end of upper hydraulic passage <NUM>. A variety of other orientation mechanisms to rotate and axially align hydraulic connectors are feasible, such as a pin that engages an orientation cam slot.

Reciprocating pump <NUM> has an intake bore <NUM> in pump intake member <NUM>. Upper conduit <NUM> has one or more seal rings <NUM> that will sealingly engage lower conduit upper bore portion 43a in this example. Upper conduit <NUM> also has a latch <NUM> that snaps into engagement with latching recess <NUM>. In this example, latch <NUM> is a collet sleeve that extends around upper conduit <NUM>. Latch <NUM> has a number of resilient fingers <NUM> that incline slightly outward relative to the exterior of upper conduit <NUM>. Each finger <NUM> has a rib <NUM> on its lower end that slides into lower conduit upper bore portion 43a, then snaps outward into engagement with latching recess <NUM>. Latch <NUM> prevents upward movement of upper conduit <NUM> relative to docking station <NUM>. One or more shear pins <NUM> may secure latch <NUM> to upper conduit <NUM>. When pump <NUM> is in its lowermost position, the lower end of intake member <NUM> will abut the upper end of lower conduit <NUM>.

To retrieve reciprocating pump <NUM>, an upward force applied from a retrieving string and fishing tool (not shown) will cause shear pins <NUM> to shear, enabling upward movement of upper conduit <NUM> relative to latch <NUM>. Fingers <NUM> deflect inward as upper conduit <NUM> moves upward, releasing latch <NUM> from lower conduit <NUM>. Optionally, a shoulder or the like at the lower end of upper conduit <NUM> retains latch <NUM> on upper conduit <NUM> during retrieval. A variety of other mechanisms for latching upper conduit <NUM> in lower conduit <NUM> are feasible.

<FIG> shows schematically one example of lower hydraulic connector <NUM> and how it fits with a connector associated with upper hydraulic passage <NUM>. In this example, lower hydraulic connector <NUM> is a male member, but it could be a female member or receptacle, instead, and the male member connected to upper hydraulic passage <NUM>. Lower hydraulic connector <NUM> includes a pin <NUM> that protrudes upward from the upper end or rim of lower conduit <NUM>. A lower portion of pin <NUM> is rigidly secured in lower conduit hydraulic passage <NUM>, such as by threads or by a press-fit. Pin <NUM> has a hole <NUM> that extends parallel to axis <NUM> from an opening at the lower end to a closed upper end. One or more lateral outlet ports <NUM> extend outward from hole <NUM> just below the closed upper end of hole <NUM>.

A valve or sliding sleeve <NUM> closely receives the upper portion of pin <NUM>. Pin <NUM> has seal rings <NUM> that seal to sliding sleeve <NUM> above and below outlet ports <NUM> when sliding sleeve <NUM> is in the closed position shown. A coil spring <NUM> encircles pin <NUM> and urges sliding sleeve <NUM> upward to the closed position shown. A retaining pin <NUM> extends laterally outward from the exterior of pin <NUM> into an axially elongated slot <NUM> in sleeve <NUM> to provide a positive upper stop for sliding sleeve <NUM>. Retaining pin <NUM> and slot <NUM> allow sleeve <NUM> to move downward on pin <NUM>, compressing spring <NUM>.

Upper hydraulic connector <NUM> includes a receptacle <NUM> extending upward from the lower end of pump intake member <NUM> and having a closed upper end. One or more outlet ports <NUM> extend laterally outward from passage <NUM> and join upper hydraulic passage <NUM>. A moveable valve or closure member <NUM> has a seal ring <NUM> that seals receptacle <NUM> below outlet ports <NUM>. Closure member <NUM> is a sliding disk capable of sliding upward in receptacle <NUM> past outlet ports <NUM>.

When pump intake member <NUM> moves downward onto lower conduit <NUM>, pin <NUM> will engage and push closure member <NUM> upward while pump intake member <NUM> continues downward movement. This results in outlet ports <NUM> opening. Sliding sleeve <NUM> has a larger diameter than the lower end of receptacle <NUM>, thus the downward movement of pump intake member <NUM> pushes sliding sleeve <NUM> downward on pin <NUM>, compressing spring <NUM> and causing pin outlet ports <NUM> to register with receptacle outlet ports <NUM>. Hydraulic fluid from lower hydraulic passage <NUM> may flow upward into upper hydraulic passage <NUM>. Other arrangements to connect hydraulic passages as reciprocating pump <NUM> is being run are feasible.

Sliding sleeve <NUM> and outlet ports <NUM> serve as means to prevent well fluid entry into lower hydraulic passage <NUM> prior to stabbing engagement of lower hydraulic connector <NUM> with upper hydraulic connector <NUM>. Sliding disk <NUM> and outlet ports <NUM> serve as means to prevent well fluid entry into upper hydraulic passage <NUM> prior to stabbing engagement of upper hydraulic connector <NUM> with lower hydraulic connector <NUM>.

<FIG> shows one schematic example of a double acting hydraulic actuated reciprocating pump <NUM>, but single acting hydraulic actuated reciprocating pumps are feasible. Reciprocating pump <NUM> has a housing or barrel <NUM> in which a plunger <NUM> reciprocates. Plunger <NUM> has a piston <NUM> that slides against the inner wall of housing <NUM>, defining an up stroke chamber <NUM> below piston <NUM> and a down stroke chamber <NUM> above piston <NUM>. Lower and upper seals or sealing surfaces <NUM>, <NUM> on plunger <NUM> above and below piston <NUM> define the opposite ends of chambers <NUM>, <NUM>. Seals <NUM>, <NUM> slide within polished bore portions of housing <NUM> that are smaller in inner diameter than the portion in which piston <NUM> slides. Plunger <NUM> has a bore <NUM> that extends axially through it for well fluid flow. The portions of plunger <NUM> extending upward and downward from piston <NUM> could have the same diameters as seals <NUM>, <NUM>.

A conventional standing valve <NUM> is mounted in hydraulic pump intake member <NUM> for opening and closing flow to a lower end of plunger bore <NUM>. A conventional travelling valve <NUM> is mounted to plunger <NUM> for opening and closing flow out an upper end of bore <NUM>. Housing <NUM> has a fishing neck <NUM> on its upper end structured for engagement by running tool <NUM> (<FIG>). The upper end of fishing neck <NUM> is open for discharging well fluid into tubing <NUM> above annular seal <NUM>.

Upper hydraulic passage <NUM> (<FIG>) connects to a hydraulic fluid line <NUM> that leads to up stroke chamber <NUM>. If a double acting hydraulic pump is employed, as shown, another hydraulic fluid line <NUM> leads from another upper hydraulic passage <NUM> (<FIG>) to down stroke chamber <NUM>. Hydraulic lines <NUM>, <NUM> can be external to reciprocating pump <NUM>, as shown, or internal. If the hydraulic pump is single acting, hydraulic pressure would be provided only for the up stroke. The weight of well fluid in tubing <NUM> previously pumped would force plunger <NUM> back downward.

Hydraulic fluid pressure supply pump <NUM> (<FIG>) to one of the upper hydraulic passages <NUM> for the double acting reciprocating pump <NUM> shown would pass through hydraulic fluid line <NUM> to up stroke chamber <NUM>. Upward movement of piston <NUM> causes travelling valve <NUM> to close and lifts the well fluid contained in tubing <NUM>. The upward movement opens standing valve <NUM>, admitting well fluid into plunger bore <NUM> below travelling valve <NUM>. When reaching the upper end of the stroke, the hydraulic pressure from supply pump <NUM> at the upper end of the well is applied to hydraulic line <NUM>, which pushes piston <NUM> and plunger <NUM> downward. Travelling valve <NUM> opens to admit well fluid from plunger bore <NUM> into tubing <NUM>, and standing valve <NUM> closes to prevent downward flow of well fluid out of plunger bore <NUM>.

The present disclosure described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. The hydraulic pump can be installed and retrieved through the production tubing. The hydraulic line or lines are installed while the tubing is being run and remain in place while the hydraulic pump is installed and retrieved.

Claim 1:
A well pump assembly, comprising:
a tubular receptacle (<NUM>) for attachment to a lower end of a string of production tubing (<NUM>);
a docking station (<NUM>) mounted to the receptacle (<NUM>), the docking station having a lower well fluid conduit (<NUM>) for receiving well fluid from the well, a lower orientation guide (<NUM>), and a lower hydraulic connector (<NUM>);
a hydraulic line (<NUM>) extending alongside the receptacle (<NUM>) and in fluid communication with the lower hydraulic connector (<NUM>) for supplying hydraulic fluid;
a hydraulically actuated well fluid pump (<NUM>) configured to be lowered into and retrieved from the receptacle (<NUM>);
a guide member (<NUM>) on a lower end of the well fluid pump (<NUM>), the guide member having an upper well fluid conduit (<NUM>) leading to an intake of the well fluid pump (<NUM>), an upper orientation guide (<NUM>), and an upper hydraulic connector (<NUM>) in fluid communication with the well fluid pump (<NUM>); and wherein
as the well fluid pump (<NUM>) is being lowered into the receptacle (<NUM>), the upper well fluid conduit (<NUM>) slides into sealing engagement with the lower well fluid conduit (<NUM>) while the upper orientation guide (<NUM>) engages the lower orientation guide (<NUM>) and rotationally orients the upper hydraulic connector (<NUM>) into stabbing engagement with the lower hydraulic connector (<NUM>) to supply hydraulic fluid pressure from the hydraulic line (<NUM>) to the well fluid pump (<NUM>).