Discussion on influencing factors of hydrocarbon generation in deep source rocks: A case study of Bozhong Sag, Bohai Bay basin

Deep layer, deep water, and unconventional areas are the inevitable trend of oil and gas exploration and development in the world. Hydrocarbon generation and accumulation are significant and challenging topics in deep oil and gas exploration, particularly in the context of the geological setting characterized by high temperature and pressure in deep layers. This study introduces an innovative approach by utilizing the findings from hydrogenation thermal simulation experiments to constrain the hydrocarbon generation kinetics parameters within the basin simulation process. By integrating these results with geochemical characteristics, key factors such as paleo-lake salinity, high temperature, excess pressure, and deep hydrogen-rich fluids were analyzed, revealing the unique characteristics of hydrocarbon generation evolution in the deep Paleogene source rocks of Bozhong Sag. It is found that salinization of lacustrine basin is beneficial to the enrichment of organic matter and the formation of high-quality source rocks. The high temperature is favorable to the thermal evolution of source rocks and hydrocarbon generation of organic matter, and it also leads to the cracking of hydrocarbons and affects the phase state of hydrocarbons. Excess pressure is conducive to the expulsion and migration of hydrocarbons and is the driving force of hydrocarbon migration and accumulation. Hydrogenation effect of deep hydrogen-rich fluids, especially near deep-seated faults, significantly improves the hydrocarbon generation potential of source rocks. The hydrogenation thermal simulation experiment has strongly confirmed this viewpoint, and with sufficient external hydrogen, the total hydrocarbon production can be increased by 2.5-3.2 times. The authors explored the influencing factors of deep hydrocarbon generation in Bozhong sag and innovatively proposed the hydrogenation effect of deep hydrogen rich fluids, significantly improved the hydrocarbon generation potential of source rocks. • Salinization of lacustrine basin is beneficial to the enrichment of organic matter and the formation of high-quality source rocks. • High temperature is favorable to the thermal evolution of source rocks and hydrocarbon generation of organic matter, at the same time, it also leads to the cracking of hydrocarbons and affects the phase state of hydrocarbons. • Excess pressure may inhibit hydrocarbon generation to some extent, it provides impetus for hydrocarbon migration and accumulation. • Deep hydrogen-rich fluid is mainly in two aspects: firstly, the obvious thermal effect promotes the maturation of organic matter in source rocks; secondly, the hydrogenation effect significantly improves the hydrocarbon generation potential of source rocks.