Abstract The Peng Lai 19-3 (PL 19-3) Oil Field, in the south-central Bohai Bay, People's Republic of China, was discovered in May 1999 with the drilling of the PL 19-3-1 well by Phillips China, Inc., a subsidiary of ConocoPhillips. The PL 19-3-1 intersected a 425-m gross hydrocarbon interval in Miocene-Pliocene sands at a depth of approximately 1000 m. The PL 19-3-2 appraisal well, located 1.6 km south-southwest of the discovery well, intersected a gross hydrocarbon interval of 525 m in the same reservoir interval. Subsequent drilling of an additional five appraisal wells has proved that a large oil accumulation exists. The oil quality ranges from 13° to 23° API, with low pour-point temperatures and low wax content. Gas-to-oil ratios are relatively low and range from 100 to 300 scf/stbo. The oil field is on the northeast extension of a large basinal high and is interpreted as a north-south-trending wrench anticline associated with a major north-south strike-slip fault system (Tan Lu fault). En-echelon northeast-southwest-trending normal faults are intersected by north-south-trending wrench faults that divide and compartmentalize the anticline. Reservoirs are a stacked sequence (600-700 m) of unconsolidated to semiconsolidated postrift fluvial-lacustrine sands of good to excellent quality in the lower portions of the Miocene-Pliocene lower Minghuazhen Formation and the Miocene Guantao Formation. Top seal consists of intraformational mudstones in the lower Minghuazhen. Source rocks are organic-rich lacustrine mudstones in the synrift Oligocene Dongying and Eocene Shahejie Formations located in adjacent subbasins. A significant portion of the oil field is masked seismically by the presence of shallow gas which covers approximately 30% (14 km 2 , or 3460 ac) of the crestal area of the structure. A four-component, on-bottom cable seismic survey was initiated in the spring of 2000 to enhance the seismic imaging of this portion of the anticline.