AAPG Southwest Section

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Identification of Potential Lacustrine Stratigraphic Intervals in the Woodford Shale, Oklahoma, Using Multi-Attribute 3-D Seismic Displays and a Supervised Neural Network


With the exploration and development of unconventional shales focused on predominantly marine deposits, the potential of hypersaline, highly restricted marine and lacustrine deposits has not been studied systematically. The primary goal for this study is to resolve whether there are seismic indicators for such rocks within a predominantly marine shale, within the Woodford Shale formation in Oklahoma. Several of the North American resource shales have been characterized as marine sequences with the common characteristic of being deposited unconformably above a carbonate formation where paleo sea level fluctuations allowed the development of erosional topography that might lead to restricted hypersaline lacustrine settings. The differences in hydrocarbon generation and cracking kinetics result in different thermal maturity windows for marine and saline lacustrine deposits, where lacustrine rocks require higher thermal maturity for oil generation and cracking. Therefore, where high thermal maturity for a rock of a marine depositional environment thermally cracks the oil, that same maturity yield, the oil might be preserved for a lacustrine deposit, thus providing previously unidentified exploration and prospectivity targets.