Sucker rods

Abstract

The disclosure relates to a sucker rod assembly for use in an oil well. The sucker rod assembly includes an elongated hollow rod having a threaded section at an end, a tubular connector having a threaded section at one end for engaging with the threaded section of the elongated hollow rod, and a second threaded section at the other end, and a tubular coupling having a threaded section at each end for engaging with the second threaded section of said tubular connector and with a second tubular coupling or sucker rod. The hollow rod, connector and coupling form a continuous hollow core for carrying fluid, cables, fiber optics or other materials.

Description

CLAIM FOR PRIORITY[0001]This application claims the benefit of priority to U.S. Provisional Application No. 62 / 676,066, filed May 24, 2018, the contents of which are hereby incorporated by reference in its entirety.FIELD OF THE DISCLOSURE[0002]The present invention relates to sucker rods used in the oil industry, in particular although not exclusively to hollow rods that allow the external insertion of a fluid, sensors and other devices.BACKGROUND[0003]In a producing oil well fluid is pushed to the surface through the well bore by the internal pressure of the reservoir. If reservoir pressure is not strong enough, artificial lift methods must be used to move fluids from the reservoir to the surface.[0004]The most common type of artificial lift applied is the sucker rod pumping system. A sucker rod pumping system uses a surface power source, pump arrangement and rod string to drive a pump assembly submerged in the fluid near the bottom of the well. It comprises several components some...

AI Technical Summary

Benefits of technology

The invention is an improved hollow sucker rod assembly for use in oil wells. The assembly has the benefits of traditional solid and fiberglass rods, but with reduced weight and corrosion resistance. The assembly has a hollow core for fluid injection, which is not possible with fiberglass rods, resulting in more efficient well production. The assembly also allows for easier introduction of chemical agents and sensors into the well without the need for additional conduits. The couplings have ports for fluid and sensors to be introduced at different depths within the well, simplifying operation and reducing costs.

Problems solved by technology

Steel is used largely because of its high tensile strength however it has the drawback of heavy weight, requiring powerful equipment to raise and lower the sucker rod string within the well.

Steel sucker rods are also susceptible to corrosion due to the presence of water and dissolved impurities in the well causing electrochemical reactions between the steel of the sucker rod.

The corrosive fluid, in which it is immersed, causes corrosion and stress-corrosion from the axial compressive bending and flexing of the string during the pumping cycle resulting in rod failures.

The steel connectors are bonded to the rod body on one surface only and potentially prone to premature failure at this point.

Fiberglass rods have poor compressive properties and when the rod string is subject to continual local compression over time due to the cyclical axial loading, premature failure can occur.

Rod failures reduce economic life of the rod string with periodic replacement required.

This contributes to the cost of oil production as the replacement of a failed rod is a time consuming and expensive process.

They have the advantage of overcoming the potential rod failures associated with multiple connection joints however the joining of sections of continuous rod by welding still has the drawbacks of potential fatigue and corrosion failure at the welded joint.

This additional pipe or tubing is time consuming to run and adds additional expense to the operation of the well.

The hollow steel rod string however still has the same inherent drawbacks of high weight and susceptibility to corrosion of a solid steel string.

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