Importance

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Abstract

A column of elastic material such as steel is lowered into an oil well by means of a derrick to a position such that the end portion thereof is within a liner to be removed. The end portion of the column has clamping means thereon which are employed to tightly clamp the column to the liner. High level and variable resonant sonic energy is then applied to the column from the surface and transmitted along the column to the liner. The sonic energy operates to loosen the liner from the surrounding earthen material which usually has an adhesive tarry substance which tightly holds the liner. Vertical bias force, which may be varied from time to time to apply variable bias both upwardly and downwardly, as well as torsional bias in some instances are employed to aid in loosening the liner, the sonic energy operating to hysteresis heat the tarry adhesive until it softens and the liner can be removed by drawing the column upwardly with the derrick.

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First Claim