Best drilling, completion and stimulation methods for CBM reservoirs

Before selecting a completion method for a coalbed methane (CBM) well, nine factors should be considered: investment required; number of coal seams encountered by the borehole; expected production rate; reserves in the various coal intervals; coal-seam permeability and gas content; type of stimulation treatment expected, if any; wellbore stability problems; future workover requirements; and artificial lift requirements, if any. To establish a set of best practices for CBM production, relationships among the selection of drilling, completion and stimulation methods and geological characteristics of coalbeds were clarified. Pertinent literature was reviewed and industry experts were queried to assure that the latest engineering practices were incorporated in the study. Industry experts from operating, service and consulting companies were selected on the basis of their expertise and the CBM basins where they operated. A questionnaire was used to gather input from industry experts.