DECLINE CURVE ANALYSIS FOR CANADIAN OIL-RESERVOIRS UNDER WATERFLOOD CONDITIONS

Decline curve analysis using type-curve matching has become an establi shed engineering tool to evaluate long-term production characteristics of oil and gas reservoirs producing under various drive mechanisms. D ecline curve analysis is often used to satisfy various regulatory requ irements, to establish reserves. and to evaluate the success or failur e of operational changes made during a reservoir's producing life. In this study, a detailed investigation of production decline data from 7 8 Western Canadian Sedimentary Basin oil pools under waterflood condit ions is presented. This study demonstrates that the majority of the wa terflooded oil pools follow a hyperbolic decline with decline curve ex ponents (''b'') less than 0.5. The decline exponent ''b'' does not exh ibit any obvious functional relationship to the type of rock, oil dens ity, geographical area, and/or geological formation. Nonetheless, such a study provides a basis for ''b'' values to be expected for Canadian oil reservoirs under waterflood conditions.