松辽盆地古龙页岩纳米孔喉体系中页岩油组分及成熟度分异效应OA北大核心CSTPCD

Micro-migration effect in continental shale oil reservoirs may lead to property differentiation of shale oil in micro-pore spaces.However,small pore radius and complex pore-throat structure of shale reservoirs are difficult to be finely characterized by conventional methods,causing unclear understanding of the microscopic enrichment mechanism of shale oil.Differentiation effect of oil components and maturity in nano-pore throat system of shale res-ervoir is revealed by experiments of stepwise extraction and low-temperature nitrogen adsorption,as well as geo-chemical analysis including total hydrocarbon gas chromatography,group component quantification,saturated hy-drocarbon gas chromatography-mass spectrometry(GC-MS)and diamondoids gas chromatography-mass spectrome-try-mass spectrometry(GC-MS-MS)of shale core samples of Qingshankou Formation in Gulong Sag of Songliao Ba-sin.The results show mesopores predominantly in the shales of Gulong Sag.With stepwised decrease of particle size of shale samples,more pores with poor initial connectivity are released,along with relative increase of heavy com-ponents and stronger polarity of hydrocarbon in microscopic nano-pore throats,and relatively higher maturity of shale oil.This is correlated with expulsion and micro-migration effect of shale oil in pore spaces with different con-nectivity.The research provides effective technical method to finely characterize microscopic occurrence character-istics of shale oil and to illustrate microscopic differential enrichment mechanism of hydrocarbon in shale oil reser-voirs,and provides reliable theoretical basis for shale oil mobility evaluation and"sweet spots"optimization.