4-D Seismic Monitoring of a Fractured Reservoir, Weyburn Field, Saskatchewan

摘要

Multicomponent (9-C) time-lapse (4-D) seismic data were used to monitor a miscible CO2 flood in a 4 horizontal injection well pattern involving a thin (30 m) carbonate reservoir at a depth of 1450 m in Weyburn Field, Saskatchewan. Time-lapse seismic images illustrate the influence of fracture zones on the flood. Open fractures significantly affect reservoir performance. Fracture zones act as a mechanism to inject a greater volume of CO2 into the reservoir and to contact oil in the fracture system. In time, however, the matrix becomes bypassed, ultimately reducing recovery efficiency unless the reservoir is effectively managed. Seismic monitoring of the 4-pattern study area shows that bypass is occurring after two years of injection and that a change in injection and production strategy is necessary to improve recovery efficiency in this reservoir.