Abstract
Gas deliveries were started from the Offshore North-West Java Sea (ONWJ) concession area to Indonesian electricity generating facilities in 1993. This paper addresses the development and reservoir engineering of shallow gas fields underlain by bottom aquifers. A multi-disciplinary team of geologists, geophysicists, reservoir engineers, production engineers and facilities engineers conducted an extensive study to optimize the development plan. This paper shows that the critical coning rates for high permeability reservoirs with a large gas column thickness are very high and the reservoirs can be drained effectively by vertical wells. Low permeability reservoirs with a small gas column thickness require horizontal wells to increase production rates and ensure high recovery efficiencies. Water breakthrough is early in the field life and there is substantial gas production after water breakthrough. This paper uses the concepts generated from single-well models to develop the reservoir depletion plans for four gas fields in the ONWJ concession.
