Utilization of sand control and mechanical profile control in numbi field water injection wells

摘要

The Numbi field is located approximately 20 miles offshore of the Cabinda enclave of Angola. The main producing reservoir in the Numbi field, the 57-05 Upper Vermelha reservoir, is comprised of a stacked sequence of near shore deposits approximately 550 FT thick. The reservoir is highly stratified and faulted, containing a hydrocarbon column that consists of a 200-FT thick oil column overlain by a 240-FT thick gas cap. The field was discovered in 1982 and placed on production in 1987. A peripheral waterflood project was implemented in 1991 to maintain the reservoir pressure and to improve the ultimate oil recovery. The field reached a peak production rate of over 85,000 BOPD after water injection was initiated. However, poor injectivity, formation sand back-flow into the injection wells, and poor injection profiles prevented the desired level and distribution of water injection from being achieved. These imbalances in injection caused gas cap expansion in some areas, and oil migration into the primary gas cap in others.