Rotary Motor Driven Reciprocating Downhole Pump Assembly

Abstract

A motor and pump assembly for use in a wellbore includes a downhole motor producing a rotary output, a reciprocating plunger for pumping fluid up a tubing string, and a drive linkage supported within the hollow tubular housing having a rotary input in connection with the rotary output of the motor and a reciprocating output which is arranged for longitudinal sliding movement with the reciprocating plunger and which is driven responsive to rotation of the rotary input to drive the plunger. The drive linkage includes a lead screw, a sleeve member having a closed end coupled to the plunger, and a follower supported on an inner side of the sleeve member in operative connection to the lead screw to drive longitudinal sliding movement of the sleeve member responsive to rotation of the lead screw.

Description

[0001]This application claims the benefit under 35 U.S.C.119(e) of U.S. provisional application Ser. No. 62 / 330,352, filed May 2, 2016.FIELD OF THE INVENTION[0002]The present invention relates to a drive assembly including a rotary motor for connection to a reciprocating pump assembly for use in a wellbore with a production tubing string having a production passage therein and at least one pump control line alongside the production tubing string.BACKGROUND[0003]In the production of hydrocarbon fluids from a wellbore, it is common to employ artificial lift in instances where the downhole pressure is insufficient to lift the produced fluids to the wellhead.[0004]One form of artificial lift comprises a progressive cavity pump in which a rotor is rotated within a stator such that cavities between the rotor and the surrounding stator progress upwardly as the rotor is rotated for lifting fluids. Progressive cavity pumps however have a limited depth of operation. Furthermore, a typical pro...

AI Technical Summary

Benefits of technology

The patent is about a pump assembly used in deep wells that uses a rotary motor and linkage to drive a linear reciprocating pump. This design provides a high lift without worrying about rod string wear. Additionally, an auxiliary conduit can be added to locate the production fluid intake at the bottom of the string even with a rotary motor. The linkage design also includes a sleeve member that isolates the linkage from the wellbore fluids and can transfer high amounts of force from a rotary input to a linear output. This solves the problems of previous designs and improves the transfer of power.

Problems solved by technology

Progressive cavity pumps however have a limited depth of operation.

Furthermore, a typical progressive cavity pump is driven by a rotating rod string which can produce wear in the surrounding casing, particularly when used in wells having a horizontal section.

Another form of artificial lift comprises use of a jet pump to accelerate fluid flow to carry the produced fluids upward, however, use of a jet pump can be limited in depth as well.

Reciprocating pumps are known to be used to provide sufficient lift for deeper wells, however, driving of a reciprocating pump typically requires a rod string extending between the downhole pump and the surface, resulting in wear problems between the rod string and the surrounding casing, particularly when there are horizontal sections in the wellbore.

The first is gas lift, which can be installed at any deviation, however, it is expensive and very inefficient as deviations increase from a few degrees past vertical.

Also this fluid lift type will become inoperative as well reservoir pressure decreases below the gas injection pressure needed to lift the hydrostatic column of fluid from the well.

The consequence to landing the bottom hole pump in the vertical section is the loss of productivity due to leaving a column of fluid in the horizontal build section above the horizontal lateral.

A rod string is thus required to communicate between the wellhead and the linkage to provide an input rotation, however, the rod string causes wear problems relative to the surrounding casing, particularly when the wellbore includes horizontal sections.

Furthermore produced fluids are required to be directed upwardly through the casing surrounding the conversion linkage so that the driving screw can become plugged with sand and other debris from the produced fluids which can prevent proper operation of the linkage.

This results in costly maintenance and loss of productivity.

The linkage is not well suited for conversion of the high forces needed for lifting from deeper wells.

Locating the fluid intake at a location spaced well above the bottom end of the string can result in considerable sand deposits and the like collecting about the motor, making it difficult to retrieve the motor, and / or to relocate the production string.

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