Wellbore plug and method

Abstract

Disclosed is a wellbore plug having a design that allows the mandrel of the plug to be made of concrete or other easy-to-drill materials. Disclosed is a wellbore plug assembly with slip and packing assemblies configured to hold the plug in place during setting and use without tensioning the mandrel, thereby allowing the mandrel to be made from easily drillable material, such as concrete.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority from U.S. Provisional Patent Application No. 61 / 505,195, filed Jul. 7, 2011, entitled “Wellbore Plug and Method,” which is hereby incorporated by reference in its entity.BACKGROUNDTechnical Field[0002]These inventions relate generally to methods and apparatus for drilling and completing subterranean wells and, more particularly, drillable wellbore plugs designed to have mandrels made of concrete or other easy-to-drill materials or shapes.[0003]In the drilling of wells and in mining applications, it is necessary to temporarily isolate sections of a wellbore. For example, a common method sets a plurality of plugs to isolate and successively treat sections of the wellbore. As used herein, the term “plug” is used to refer to bridge plugs, packers, frac plugs, cementing shoes, squeeze plugs and the like utilized at subterranean wellbore locations. This isolation method has been accomplished using “drillable wel...

AI Technical Summary

Benefits of technology

The present invention introduces a drillable downhole tool with easy-to-drill materials such as concrete for its mandrels. The design utilizes a double-slip configuration plug and a setting tool that reduces tension stresses on the mandrel during setting and use. The invention also provides a method for setting a tool using a setting rod connected to the mandrel near the bottom of the tool. The design eliminates tension forces on the mandrel during the setting process and use, allowing for the use of smaller cross section mandrel designs and materials with lower strength requirements. This results in a tool that is easier to manufacture and use in wellbore operations.

Problems solved by technology

While conventional plugs are in use or held in place, differential pressures across the plug can induce tension and compressive stresses in the mandrel.

Plugs of the double-slip configuration have a disadvantage of requiring substantially higher setting forces than the other configurations of plugs, and therefore the plugs' components, in particular the mandrel, experience substantially higher internal tension stresses during setting.

While mandrels made from high-strength plastic materials are easier to drill out than mandrels made from metallic materials, problems have been experienced in the drilling out of these mandrels.

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