Port Acres and Port Arthur fields are located on the Gulf coastal plain of southeast Texas near the Louisiana border, northwest of the town of Port Arthur, Jefferson County, Texas. The fields lie along the downdip part of the Frio (Oligocene) sandstone producing trend and on a semiregional positive feature generally referred to as the Vicksburg platform. Port Acres field is a classic example of a primary stratigraphic trap, whereas Port Arthur is a combination structural-stratigraphic trap producing from locally deposited lower Hackberry sandstones on an anticlinal closure which developed on the downthrown side of a contemporaneous fault. Significant events of the predevelopment exploration between 1943 and 1957 included seismic surveys and the drilling of several wells. he major reserves at Port Acres are in the lowest sandstone unit of the lower Hackberry sandstone zone. Reserves at Port Arthur are in the middle Frio and in 11 sandstones in the lower Hackberry.

The limited effectiveness of the seismograph is demonstrated by comparison of the prediscovery interpretation with the interpretation after field development. The lower Hackberry sandstone section represents a delta extending seaward from the mouth of a stream ancestral to the Neches or the Sabine River; deposition was influenced initially by the uplift of Spindletop salt dome on the northwest. Later growth of the Port Neches salt dome on the northeast affected the structure in the area.

Port Acres field covers 3,200 acres on which 55 wells have been completed; Port Arthur field covers approximately 1,700 acres on which 14 wells have been completed. Reserve estimates indicate that the Port Acres-Port Arthur fields ultimately will produce 400 billion cu ft of gas and 20 million bbl of distillate.

The productive lower Hackberry sandstone section was deposited within the framework of a middle Tertiary delta. Similar sandstones should be present elsewhere in the Gulf Coast across the eroded surface of the Vicksburg platform, and it is likely that some will be found to contain petroleum accumulations.