AAPG Foundation 2019 Grants-in-Aid Projects

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Petroleum retention and resource prediction in the Es3 lacustrine shales, Dongpu Depression, Bohai Bay Basin, China


Balance of petroleum expulsion and retention in organic-rich shales is receiving more attention because of increasing global shale oil exploration and development. Petroleum expulsion and retention characteristics may vary markedly in a complex lacustrine shale oil system, which cause difficulties in shale oil resource estimation. This project aims at understanding evolution of shale oil system during thermal maturation from laboratory work and establishing an applicable quantitative method for resource estimation of lacustrine shales. Artificially matured shale samples are prepared by performing semi-open pyrolysis on an immature lacustrine shale sample from the Es3 Formation in the Dongpu Depression, Bohai Bay Basin, China. In this way, shales with high to low hydrocarbon expulsion efficiency are obtained, while effect of depositional heterogeneity is avoided. Then, Rock-Eval pyrolysis, Thermovaporization-Gas Chromatography and Pyrolysis-Gas Chromatography are conducted on these samples to characterize the compositional evolution of shale oil system during thermal maturation, including free/adsorbed oil retention, oil expulsion and residual hydrocarbon generation potential. On the basis of experimental data, quantitative method to evaluate shale oil resource potential is established. Combined with 3D basin modeling software and geochemical data of natural shale samples, result from laboratory study is extrapolated to complex geological conditions and the quantitative method is applied in evaluating shale oil resource potential of the Es3 Formation in the Dongpu Depression. The result of this study is expected to aid in reasonable estimation of resource potential in complex lacustrine shale oil system and providing theoretical guidance on shale oil exploration.