Triple branch completion with separate drilling and completion templates

摘要

A method, and apparatus to practice the method, to complete multiple (triple) branch wells using separate drill and casing templates. Principally this invention finds its greatest utility in the in situ leach mining of deep lying ore bodies. Initially, a generally vertical main hole is drilled in the earth and cased. The particular casing used has an internal indexing dog and specific areas which act as windows from which some of the branch wells are to be drilled. To form the individual branch wells, each window is sequentially drilled out by a drilling assembly which is oriented by a movable drilling template. The template is fixed with respect to the casing for each branch drilling by engaging the indexing dog. After each window and branch well is drilled, the drilling assembly and drilling template are retrieved to the surface and repositioned with respect to each other to provide for the next branch drilling. A whipstock assembly is used in connection with the drilling template and indexing dog to positively locate each branch well. After all branch wells are drilled, the whipstock assembly is retrieved. Next a triple tubing guide or template, which can engage the same indexing dog, is used to simultaneously position branch casings in each of the previously drilled branch holes. A tubing hanger is used to position and hold these casings within the main casing. Cement baskets are attached to the shoe (end) of each branch casing and all casings are cemented in place. Lastly, the branch wells may be perforated, unless this has been done in the casing production process, and the well is then ready for production.