Three-Dimensional Architecture of Lowstand Incised-Valley Deposits in the Woodbine Group, North East Texas Field

Analysis of closely spaced wireline logs and 1,500 ft (>450 m) of core from 30 wells within the Upper Cretaceous (Cenomanian), lower Woodbine Group in the north part of East Texas field reveals complex sandstone-body architecture. This study focuses on the north pilot area (NPA), where lowstand, coarse-grained, bedload fluvial deposits truncated an underlying succession of fluvial-dominated highstand deltaic deposits.

Two systems tracts with two distinct depositional systems comprising significant sandstone bodies are recognized in the NPA. The lower interval is composed of a fluvial-dominated, deltaic depositional succession, deposited during highstand that typically, has dip-elongate distributary-channel sandstones. The upper interval consists of a lowstand incised-valley-fill succession composed of multistoried, coarse-gravel conglomerate and coarse-grained sandstone beds that erode down more than 100 ft (30 m) into the underlying highstand deposits. Recognition of the size, shape, and distribution of sandstone bodies allows assessment of reservoir compartmentalization and analysis of fluid-flow pathways and provides a geological framework for identifying potential unswept mobile oil in East Texas field.