Depositional Environments and Basinal Setting of Cretaceous Woodbine Sandstone, Central and Northeast Texas: ABSTRACT

Abstract

The Upper Cretaceous (Cenomanian) Woodbine Sandstone of central and northeast Texas has long been one of the largest oil and gas producers in Texas. North of the Angelina-Caldwell flexure, production is at moderate depths of 3,000-6,000 ft from fluvial and subaqueous deltaic facies. South of the flexure, the undifferentiated Woodbine-Eagle Ford interval produces from depths between 10,000 and 15,000 ft from fractured turbiditic channel siltstones and sandstones. This investigation (1) more precisely defined environments of deposition, (2) determined their relationships to development of the East Texas basin, and (3) related these environments to hydrocarbon production. Much greater control was used than in previous studies, including an extensive core study (approximately 70 cores), close well control (approximately 1,200 electric logs), and an outcrop study. In general, the depositional environments of the updip Woodbine change progressively from a complex fluvial system in the northeastern portion of the study area to delta plain, delta front, and prodelta shelf in a southwestward direction. Major fluvial axes are oriented north-northeast to south-southwest. The fluvial system includes (1) a braided stream facies, (2) a distributary channel facies, and (3) a meander belt facies. The two principal recognizable facies of the delta front are coastal barrier sands and progradational channel-mouth bar sands. Woodbine deposition ended with transgression of Eagle Ford seas and subsequent deposition of marine shales. These shales provide a potential hydrocarbon source and seal for Woodbine reservoirs. End_of_Article - Last_Page 142------------