ABSTRACT

Pressure, temperature, salinity, lithology, and structural studies indicate that hydrocarbons in Deep Lake, Constance Bayou, and Little Pecan Lake fields, were generated in the shale beds of the hard geopressured zone and migrated upwards along major growth faults. The hydrocarbons were originally dissolved in hot fresh pore water and came out of solution in the overlying low temperature and pressure zones, accumulating in the sand beds of the first structural traps encountered. By examining regional cross sections and anomaly maps, fluid escape routes taken by the hot pore water containing dissolved hydrocarbons can be identified. Areas below which a vertical flush of hot fresh pore water from the hard geopressured zone has occurred have three identify characteristics: low fluid pressures, high formation water salinity values, and presence of residual high pressure areas. These areas are considered to be highly prospective places to search for hydrocarbon accumulations. There are five areas in the study area below which a vertical flush has occurred from the hard geopressured zone and each contains commercial accumulations of hydrocarbons.

This report concludes that pressure, temperature, and salinity studies, when coupled with lighology and structure, add a new dimension to hydrocarbon exploration and should definitely be used in the search for new reserves of oil and gas.