Subsurface Distribution and Reservoir Properties of Wire-line Log Derived Depositional Cycles in the Atokan Bend Group, Denton County, Fort worth Basin, Texas

Abstract

The purpose of this study is to examine the Bend Group in Denton County, Fort Worth Basin TX. The objectives include: a discussion of fan-delta depositional processes, depositional cycles, and environment; the construction of maps to illustrate structure, geometry, trend, and source direction of the Bend Group and associated depositional cycles; recognize depositional cycles utilizing well log signatures; construct various cross sections to develop a depositional model; analyze porosity and water saturation of the various depositional cycles; and to evaluate petrographic and diagenetic characteristics of the Bend Group. Four different depositional cycles were identified using well logs and correlated with core. Gross isopach maps of each of the four depositional cycles show lobate geometries that trend northeast indicating a northeasterly transport direction. Depositional cycles with the best porosity development and reservoir potential were distributary channels. Due to its better porosity development and widespread distribution, the DC-4 distributary channel package is the most suitable target for hydrocarbon exploration within the study area. The detrital mineralogy of the Bend Group is dominantly quartz with varying amounts of granitic rock fragments and feldspar. Porosity is mainly secondary and is the result of dissolution of rock metastable grains and fracturing.