Abstract

Coil Tubing technology grew as an off-shoot of the military needs during World War II. One such need was the requirement to spool continuous lengths of flexible pipeline across the English Channel, and the other post WWII need was to spool out long lengths of communication antenna from submerged submarines. These early advancements laid the ground work for other industries to capitalize on.

It didn't take long for oilfield engineers to figure out the advantages of a continous tubing string for drilling and for working over wells. The need to ‘inject’ coil into a well bore under pressure has resulted in numerous designs, but they all have the basic components of the Injector Head with Guide Arch, Stripper, and a Quad BOP Stack.

As with all oilfield tubulars, the eventuality of having the pipe stuck due to unforeseen circumstances created a satellite industry in removing such stuck tubulars. Many downhole fishing tools have been borrowed from their larger threaded cousins, i.e. tubing, drillpipe and casing strings.

This paper briefly reviews the current techniques of extracting stuck coil tubing strings using downhole intervention, and presents a 12 year old process of surface intervention only, using Surface Resonant Vibratory Energy. Rig up procedures and case histories of this surface technique will be presented along with some engineering theory of the underlying acoustic principles of pipe extraction.

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