Hydrocarbon generation and expulsion modeling of different lithological combination source rocks from the Funing Formation in the Subei Basin

The oil expulsion efficiency and retention of shale affect the enrichment preservation oil. Two series semi-closed hydrous pyrolysis experiments were performed under in situ geological conditions on a Paleogene sample as comparable analog to evaluate generation potential Funing Formation Subei Basin. results show that 1) oil-generation capacity evolution different lithological combination source rocks Basin can be roughly divided into four stages: a) relatively slow oil-generating gas-generating, b) fast c) cracking gas, d) kerogen gas; 2) combinations have hydrocarbon generation, expulsion, efficiencies. total rate gas pure are higher than those with silty interlayer, exchange point between is earlier which indicates experienced process earlier. Oil mainly occurs at an EqVRo 0.84%–1.12%, while discharged adjacent siltstone 1.12%–1.28%. Based simulation conditions, it recognized for exploration Basin, favorable thermal maturity lithology interlayer. On one hand, interlayer provide pore space early generated oil, concentration difference hydrocarbons formed so continuously enter other above used cap rock preserve area high (at VR value about 1.1%)