Kinetics of shale oil generation from kerogen in saline basin and its exploration significance: An example from the Eocene Qianjiang Formation, Jianghan Basin, China

Abstract

In this study, confined pyrolysis experiments were performed on kerogen from the Qianjiang Formation in the Jianghan Basin, China, to investigate hydrocarbon evolution in the inter-salt shale deposited in the basin. Kinetic parameters obtained from the pyrolysis experiments were applied to reconstruct the history of hydrocarbon generation in the Eq34–10 cyclothem inter-salt shale reservoir. The results indicate the following: (a) The source rock deposited in the salt basin has a high hydrocarbon potential and a low activation energy for hydrocarbon generation. Petroleum can be generated at a lower maturity stage, and the maximum yield is reached at an EasyRo% of approximately 0.75 %. (b) Hydrocarbon generation from the Eq34–10 cyclothem inter-salt shale reservoir started at approximately 36–33 Ma. The current conversion rates (total oil) for the shale are approximately 0.59, 0.97, 0.97, and 0.88 in wells designated A, B, C, and D, respectively. (c) Deeper shale oil characterized by a high proportion of saturated hydrocarbons migrated laterally and were concentrated in the anticlinal area with shallow burial depth. In regions where structural traps form, lateral up-dip oil migration along variably deformed shallow shale laminates are conducive to the formation of shale oil systems. In thermally mature source kitchens, continuous shale oil accumulation in structurally undisturbed areas still provides attractive shale oil drilling targets.