Flow back jet pump

A jet pump assembly is adapted to be releasably attached to a tubular member of a tubular string in an oil well. The jet pump may be pumped out of the tubular string to the surface by a reverse flow of power fluid down the well between the tubular string and the casing of the well. Consequently the jet pump may be serviced or reconfigured to a direct pumping mode without the necessity of a wire line or other apparatus. A sensor for measuring downhole parameters such as temperature and pressure etc. is positioned within a cavity located in a lower portion of the jet pump so as to be removable from the well with the pump.

BACKGROUND OF INVENTION

1. Field of the Invention

This invention relates to jet pumps that are used to lift fluids such as water and oil from the interior of an oil well. Pumps of this type utilize a nozzle and a venturi tube to create a pressure drop which can draw fluid from a location in the well below the pump. The power fluid and produced fluid from the well are then comingled in a mixing tube and diffuser where the pressure is increased to a point where the power and produced fluids are forced to the surface of the well where the produced fluids can be separated.

2. Description of Related Art

Jet pumps as described above are known that include a subassembly of the pump to be circulated back to the surface for servicing for example, by reverse flow of the power fluid. In normal operation, power fluid under pressure is pumped down a tubular positioned within the well casing and the mixture of the power fluid and produced fluid is conveyed upwardly in the annulus between the tubular and the casing. To pump back certain subassemblies for service, for example, the power fluid is pumped down the annulus and forces the subassembly up through the tubular.

Also, jet pumps are known that can be operated in a direct flow or reverse flow configuration. The nozzle assembly can be retrieved at the surface and replaced by a reverse flow nozzle arrangement. In this configuration, it is necessary to provide a stop mechanism to prevent the nozzle assembly from being pumped back to the surface in the reverse flow position. The stop mechanism may include a plurality of dogs on the pump housing which extend into an annular pocket found on the interior surface of a sub that surrounds the pump housing. A conventional tool may be used to pivot the dogs out of the pocket when it is desired to remove the inner components of the jet pump.

However, the prior art does not include an entire jet pump assembly that can be installed in the reverse flow mode and subsequently removed from the tubular string without the use of a wire line.

BRIEF SUMMARY OF THE INVENTION

The invention disclosed and claimed herein is directed to a jet pump of the type discussed above that can be totally removed from the tubular string. The pump is releasably held in place for reverse flow operation and can be removed by a tool that can be pumped down to the pump without the use of a wireline.

The tool is adapted to release locking dogs attached to the pump assembly and at the same time to attach to a fishing neck at the top portion of the pump assembly. The tool includes seals that engage the interior surface of the tubular string to facilitate the pumping out of the entire pump assembly when desired. In this manner the entire pump assembly can be removed from the tubular string as a unit without the necessity of a wireline or work over rig.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 1the jet pump assembly10according to an embodiment of the invention is positioned within an outer tubular member11having an upper end12and lower end13adapted to be connected to a tubular string which extends within the casing (not shown) of an oil/gas well. Outer tubular member11is generally of the same diameter of the tubular string such that an annual gap exists between the outer surface of the outer tubular member11and the casing of a well. The upper end12of tubular member11includes an annular shoulder62and an annular recess61. Recess61receives a plurality of pivotably mounted dogs15pivoted at67that cooperate with shoulder62to normally prevent upward movement of the jet pump unit within tubular member11when the jet pump assembly is in the reverse flow mode as shown inFIG. 1.

The jet pump assembly includes a jet pump housing16having an upper portion14, intermediate portions27,22and a lower portion25. Lower portion25includes a lateral, diverging port24which in the reverse flow mode shown inFIG. 1acts as an inlet port. In the direct flow mode port24acts as an outlet port. A sensor75for sensing downhole parameters such as pressure and temperature etc. is attached to a bottom portion17of lower portion25of the jet pump housing within a cavity74.

A carrier member21is positioned within jet pump housing16and provides support for a mixing tube23and a jet nozzle32as shown inFIG. 2. A plurality of apertures33are provided in the carrier member21adjacent jet nozzle32.

In the configuration shown inFIG. 1, power fluid is pumped down the annulus between the casing and tubular string and enters the interior of tubular member11through a plurality of apertures53provided in middle portion36of tubular member. The power fluid then enters port24and converging passageway51of the carrier member. At this point the velocity of the power fluid is increased and the pressure is reduced as is well known in the art.

As the power fluid exits nozzle32, a further pressure reduction occurs and formation fluid is drawn up through lower portion17of the jet pump housing16. The produced fluid passes through apertures33from a chamber28and is subsequently mixed with the power fluid in mixing tube23. From there the mixture expands in divergent passageway52where the velocity decreases and the pressure increases thus enabling the mixture of power fluid and produced fluid to flow upwardly to the well head.

Should it be desired to retrieve the entire jet pump assembly for example, in order to service the pump or to reconfigure it to operate in a direct mode with the power fluid pumped down the tubular string, the entire jet pump assembly can be pumped up without the need of a wire line in the following manner.

An attachment tool80as shown inFIG. 3is pumped down to engage the jet pump assembly. Attachment tool80includes a cylindrical body portion81and a cylindrical rod82extending downwardly from body portion81. Rod82engages dogs15to move them out of annular recess61. At the same time, latches within body81of the tool engage fishing neck71of the jet pump housing and upper portion14in a manner known in the art.

Attachment tool80also includes a plurality of seal cups83which engage the inner surface of the tubular string. Thus after the dogs15have been moved out of annular recess61and fishing neck71has been engaged, the entire pump assembly including jet pump housing16and carrier21may be pumped up by fluid entering through port24.

The pump may be reconfigured to a direct flow mode by repositioning the nozzle32and mixing tube23such that power fluid will pass down the tubular string to first enter the nozzle and then flow into the mixing tube23and diffuser51as shown inFIG. 4. A plurality of seals76are positioned between the pump housing and tubular11.

An example of a well know attachment tool that may be utilized is the model BT “JDC” pulling tool made by Brace Tool located in Alice, Tex. It has been modified by inclusion of the seal cups83and an upper fishing neck84.