PALEOENVIRONMENT, KEROGEN TYPE, AND THERMAL MATURITY OF THE WOLFCAMP SHALE IN MARTIN COUNTY, TEXAS

Martin County, Texas has been one of the Permian Basin’s major oil and gas producers for over 50 years. The Wolfcamp shale is among the leading, but challenging, plays in the region due to its heterogenetic nature as well as low index of brittleness. Accurate knowledge about the Wolfcamp’s temporal and spatial variabilities in terms of source-rock parameters is specially needed in order to maximize its liquid hydrocarbon production capability. By integrating palynofacies and pyrolysis data, important information about kerogen type, stage of thermal maturity, and depositional paleoenvironment can be garnered. Twenty samples were palynologically studied from four separate wells to describe their organic matter content. The organic assemblage was categorized into seven groups with degraded phytoclasts being the most prominent, suggesting a depositional paleoenvironment that is strongly influenced by terrestrial organic matter. Pyrolysis of 46 samples from the four wells revealed a mixture of type-II and type-III kerogen (oil and gas prone materials). Average T_max values in each of the four wells place them well in the liquid hydrocarbon generation window.