METHOD FOR FORMING A CASING WINDOW

摘要

The method and apparatus of the present invention allow the creation of a window in casing downhole using explosive techniques. Locating stakes (10) are initially placed and subsequently surveyed for their depth and orientation. The window-cutting tool locates itself on one of the stakes, and the explosive charges are oriented with respect to the lug downhole so that when the tool is fired, the cuts are made with the appropriate orientation at the proper depth. In the preferred embodiment, horizontal cuts are made, followed by vertical cuts. The tool has the capability of positioning itself adjacent the casing which is to be explosively cut. The strips that are created after the horizontal and vertical cuts are concluded are fished out using a variety of alternative techniques. Another locating or orienting lug, which has been initially installed, can subsequently be used to locate and orient an anchoring device for a whipstock so that the sloping face of the whipstock is pointed directly at the window that has just been explosively cut.