Multiple branch completion with common drilling and casing template

摘要

A method of drilling and completing multiple branch wells extending from a main generally vertical hole. This invention finds its primary applicability in in situ leach mining of deep (500 to several thousand feet) lying ore bodies such as uranium, copper, etc. Initially, the main generally vertical hole is drilled, cased, and cemented. Whipstock drilling guides are placed to extend downwardly and outwardly from the bottom of the casing for this hole and cemented in place. These guides are the same in number as the branch holes to be drilled. In addition, the well bore casing contains an indexing dog just above the whipstock drilling guide. The actual drilling of the branch wells is accomplished with a floating index collar and a drill bit assembly which runs therewith. The indexing dog is fixed in the main hole and engages the indexing collar so that the drill bit is oriented to drill into one of the whipstock drilling guides. After a particular branchis drilled, the collar and bit are retrieved from the main hole. The bit is then placed in another hole of the collar and the combination reinserted in the main hole where it again engages the indexing dog and allows drilling of another branch well. After all branch wells are drilled, they are cased with a flexible casing, like fiberglass, cemented and selectively perforated. If the well is a liquid recovery well, a pump is placed at the bottom of the main vertical hole casing near where it joins the branch wells.