CO_2 STORAGE AND ENHANCED METHANE PRODUCTION: FIELD TESTING AT FENN-BIG VALLEY, ALBERTA, CANADA, WITH APPLICATION

摘要

Micro-pilot field tests were performed at Fenn-Big Valley, Alberta, Canada in a four metre-thick Mannville Formation coal seam by injecting four different gas mixtures: 100% CO_2, 47% CO_2-53% N_2, 13% CO_2-87% N_2 and 100% N_2. Before injection, the well was on production for 30 days to obtain gas- and water-productivity data and produced-gas samples for composition determination. The production period was followed by a shut-in test. The pressure data collected during the shut-in period were analyzed to obtain permeability estimates before gas injection. During injection for each micro-pilot, injectivity was maintained at adequate rates (～0.5 (10~6) scf/D or 15(10~3) m~3/D) in this low one to four md-permeability Mannville reservoir. Soak periods ranged from 30 to 60 days. Then the well was returned to production for 30 days to determine the well's productivity and composition of the produced gas. This huff and puff test was followed by a final shut-in test to obtain pressure and permeability measurements after injection. These data are being used to calibrate reservoir simulators to estimate the CO_2 storage potential and the enhanced hydrocarbon gas recovery in the design of multi-well pilots and for preliminary economic evaluations. These field tests led to the conclusion that low-permeability coal seams which may not be commercial under primary production could still be CO_2 storage sites with the added benefit of improving the possibilities for commercial gas production.