| 摘要 |
A joint of tubular casing with a pre-formed window in its sidewall, has a tubular sleeve fixedly attached to the interior of the tubular casing by a plurality of shearable fastners. The exterior surface of the sleeve is sealed to the interior surfa ce of the tubular casing on opposing sides of the window using a pair of high pressure seal assemblies. The window cavity is filled with a fluid and then the window is covered with one or more layers of a composite material such a fiberglass. In use, the joint of tubular casing is run down to the depth of interest in an earth borehole, and then t he window is oriented with respect to the formation of interest at the depth. The joint o f tubular casing is then cemented in place, after which the tubular sleeve is retrieve d by the use of a fishing tool causing the set screws to shear upon the upward movement o f the fishing tool. After the interior sleeve is retrieved, a whipstock is lowered into the cased borehole, until it is oriented and anchored therein.
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