The Nembe Creek field, discovered in 1973 in the coastal swamp of the Niger delta, is developed in a middle Miocene deltaic sandstone-shale sequence. Oil accumulations, with some associated and unassociated gas, have been found in the depth range of 7,000 to 12,000 ft (2,134 to 3,658 m). The oils have gravities between 16° and 41° API, the heavier oils coming from the more shallow reservoirs. Drilling of 30 wells by the end of 1977 increased average recoverable oil reserves to 645 million bbl. Nearly one-third of these wells were proposed with direct support of reflection seismic data, used principally for structure-mapping and development of cross-sections. In addition, lateral predictions of lithology and sand pore fill for two appraisal wells came from comparis n of true amplitude impedance profiles and synthetic seismograms generated from well data. It is concluded that the timely acquisition and interpretation of sufficient seismic data in an area of complex structure (but good reflection quality) permitted the successful drilling of long step-out appraisal wells. This approach led to an early delineation of the field's limits, a rapid growth of proved reserves, and a firm basis for proposal of an additional 70 development and appraisal wells (as yet undrilled).