Abstract
The Huizhou 6S and 3S oil fields in the Pearl River Basin, Offshore South China Sea are mature fields which have produced 40% to 60% of their original oil in place since 1991. Currently the field production is rapidly declining and water production is increasing. However, through reservoir surveillance data, geologic and reservoir modeling, significant recoverable oil was identified in shaly sandstone reservoirs and attic structural locations of clean sandstone reservoirs. As a result, a comprehensive portfolio of prospects has been built for a robust development program. Horizontal wells were utilized to improve oil recovery in shaly sands and to reduce water coning in thin remaining oil columns. Horizontal drilling best practices were applied during well planning and drilling executions, such as optimum well designs, specific LWD/MWD tool selections, low fluid loss drilling fluids, real-time geosteering data monitoring and the cleaning of the pay zone during completions were applied to maximize reserve recovery and successfully reverse the field's production decline.
