CO2 storage and enhanced methane production: Field testing at Fenn-Big Valley, Alberta, Canada, with application

Publisher Summary An extensive testing program is conducted on two wells completed in Medicine River Coal seams in the Alberta Plains region. By sequential injection, soak, and production tests, along with accurate bottom-hole pressure and produced-gas composition monitoring, an understanding of the enhanced coalbed methane—CO 2 storage process is increased. The detailed data resulted in conclusions that were opposite to general beliefs before the project started. It was generally thought that CO 2 injection would be hindered by coal swelling caused by CO 2 sorption. It is found that the opposite to be the case as CO 2 injectivity is greater through the use of alternating injection shut-in sequences and perhaps as a result of coal weakening. Data is found to be very useful to investigators who are developing reservoir simulation software to model primary and enhanced recovery from coal seams. These data can serve as history-matching files to test the accuracy of the modeling methods. The calibration of the numerical simulators using these field data allows predictions to be made on commercial opportunities for CO 2 storage production for Mannville coals. The combination of these three observations suggests that low-permeability coal seams that may not be commercial under primary production could still be CO 2 -storage sites with the added benefit of improving the possibility for commercial gas production.