Method of driving a well pump

Abstract

Production liquid from a well is pumped to the surface by a hydraulically driven reciprocating piston pump. The pump is driven in a drive stroke by a flow of hydraulic fluid supplied through a single tubing line applied to a drive side of a drive piston and in a return stroke by the weight of the production liquid heavier than the hydraulic fluid applied to the return side of the drive piston. The production liquid is pumped though the well casing. A control valve causes application of pressure in the hydraulic fluid for the drive stroke and release for the return stroke. The pump body includes a first duct communicating between the tubing and the bottom drive side of the drive piston and a second duct communicating between the well casing and the top drive return of the drive piston.

Description

[0001]This invention relates to a method of driving a well pump.BACKGROUND OF THE INVENTION[0002]Down-hole hydraulic pumps with the valving, piston and pump (and its variations) were originally developed under the trade names “Kobe” and “Oilmaster”. Both have been available to the industry for more than five decades. The product enjoys worldwide acceptance under the current direction of Weatherford Oil Tool. These pumps find special application lifting large volumes of light oil in deep wells.[0003]More recently Canadian application 2,258,237 by Cunningham suggested bringing the valving to the surface, and proposed using a downhole double acting hydraulic piston, three (3) strings of tube and a conventional oil well pump for placement in a horizontally drilled heavy oil well. The double acting feature of the hydraulic piston would be particularly useful as a pump pull-down in the highly viscous heavy oil applications for which the system was conceived.[0004]Canadian application 2,26...

AI Technical Summary

Benefits of technology

[0057]The arrangement herein is based on the concept that by setting a packer and supplying the hydraulic pressure through a single tubing in the well casing, two hydrostatic columns exist in the well bore. One of the columns can be used to produce the well and operate the intake stroke of the pump while the other column can be used in conjunction with a hydraulic pump at surface to operate the displacement stroke of the pump. The system may offer one or more of the following advantages:

[0062]5. Live well operations can be safely carried out by the CT unit with superior well control at all times.

[0064]7. Due to the utilization of differential areas and force multiplication within the pump a low horsepower hydraulic surface pump will move the nearly hydrostatically balanced columns efficiently.

Problems solved by technology

The disadvantages of an insert pumping system are widely acknowledged in the oil and gas industry.

Up front capital costs to install a pump jack, rod string and insert pump are significant and require the use of a workover rig.

Day rates and availability of workover rigs in periods of high activity warrant special consideration but generally are viewed as a necessary evil and are accepted as a cost of doing business.

Once installed, this pumping system requires regular maintenance, mobilization of a workover rig is again necessary in addition to the costs of replacing tubing, rods and the BHP during the workover.

Images