COMANCHEAN CRETACEOUS OUTCROP SEQUENCE STRATIGRAPHY AND FACIES ANALYSIS OF TEXAS: IMPLICATIONS FOR ENHANCED PETROLEUM EXPLORATION

An integrated sequence stratigraphic classification of the Comanchean Series, Cretaceous strata in the Gulf Coast is developed for northeast and south central Texas. Four Aptian-Albian to Lower Cenomanian, second order, transgressive-regressive (T-R) sequences are recognized. The lower T-R K1 sequence consists of the Sycamore, Hammett and Cow Creek formations. The T-R K2 sequence includes the Hensel, lower Glen Rose, and upper Glen Rose units and the lower beds of the Paluxy Formation.The T-R K3 sequence consists of two higher order sequences, the first of which includes the upper beds of the Paluxy and Walnut, Goodland and correlative Comanche Peak and Edwards formations, and the second comprises the Georgetown Limestone and the coeval units of the lower part of the Washita Group. The T-R K4 sequence includes the upper Washita Grayson/Del Rio and Buda formations. These sequences can be correlated across Texas and from the western to eastern Gulf. Because the stratal architecture of these sequences delineates potential reservoir facies, this classification has implications for developing enhanced petroleum exploration strategies. Stratigraphic intervals with reservoir potential include: grainstone and rudist reef beds of the Sligo Formation, Cow Creek Limestone (James Limestone), lower Glen Rose (Rodessa Formation), upper Glen Rose (Mooringsport Formation), Walnut and Goodland/Comanche Peak and Edwards formations (Andrew Formation and Fredericksburg Group) and Washita Group, and fluvial to shallow water sandstone beds of the Hosston, Donovan, Paluxy and Dantzler formations and Fredericksburg Group.