Structural, stratigraphic, and petrophysical controls on natural gas production from the Travis Peak and Pettet formations, Lower Cretaceous, in the Overton Field, Smith County and Cherokee County, East Texas

The Travis Peak and Pettet Formations are two major hydrocarbon producing trends of Lower Cretaceous time in the East Texas Basin. A field study was conducted in Overton Field of Smith and Cherokee counties, east Texas to determine the structural, stratigraphic, and petrophysical characteristics of the Travis Peak and Pettet Formations. Wireline well log correlation and petrophysical analyses were used to determine petrophysical characteristics that included: shale volume, effective porosity, and water saturation. Subsurface isopach maps were constructed to determine the depositional environment and the areas of potential hydrocarbon production. Two depositional environments were proposed for the Travis Peak Formation. The upper Travis Peak depositional environment is interpreted as a tidal flat setting where tides rework the clastic sediments. The deposits are dominated by clean sandstones separated by siltstones representing spring and neap tide bundles. The lower Travis Peak depositional environment is interpreted as a tide-dominated estuary where clastic sediments were trapped and reworked. The deposits are dominated by clean sandstone separated by thin siltstone deposits representing 4 th and 5th order transgressions. The Pettet Formation depositional environment is interpreted as a shallow marine oolite shoal setting. The deposits represent subtidal carbonate lithofacies cycles recording 4 th order transgressive cycles. The study of the structural, stratigraphic and petrophysical characteristics were used to construct reservoir maps of the Travis Peak and Pettet Formations to show the formations potential for production of hydrocarbons. Potential for production exists in both the Travis Peak and Pettet Formations within Overton Field.