Maceral evolution of lacustrine shale and its effects on the development of organic pores during low mature to high mature stage:A case study from the Qingshankou Formation in northern Songliao Basin,northeast China  

作　　者：Liu Wang Bo Liu Long-Hui Bai Mehdi Ostadhassan Thomas Gentzis Bo-Yang Wang Yi-Zhang Wang 

机构地区：[1]Key Laboratory of Continental Shale Hydrocarbon Accumulation and Efficient Development,Ministry of Education,Northeast Petroleum University,Daqing,Heilongjiang,163318,China [2]Accumulation and Development of Unconventional Oil and Gas,State Key Laboratory Cultivation Base,Northeast Petroleum University,Daqing,Heilongjiang,163318,China [3]Core Laboratories,Reservoir Geology Group,6316 Windfern Road,Houston,TX,77040,USA [4]Exploration and Development Research Institute of Daqing Oilfield Co Ltd,Daqing,Heilongjiang,163712,China

出　　处：《Petroleum Science》2023年第5期2709-2725,共17页石油科学（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(41972156);the Natural Science Foundation of Heilongjiang Province(TD 2021D001).

摘　　要：Organic matter(OM)hosted pores are crucial for the storage and migration of petroleum in shale reservoirs.Thermal maturity and macerals type are important factors controlling the development of pores therein.In this study,six lacustrine shale samples with different thermal maturities from the first member of the Qingshankou Formation in the Songliao Basin,of which vitrinite reflectance(R_(o))ranging from 0.58% to 1.43%,were selected for a comparative analysis.Scanning electron microscopy(SEM)and reflected light microscopy were combined to investigate the development of organic pores in different macerals during thermal maturation.The results show that alginite and liptodetrinite are the dominant primary macerals,followed by bituminite.Only a few primary organic pores developed in the alginite at the lowest maturity(R_(o)=0.58%).As a result of petroleum generation,oil-prone macerals began to transform to initial-oil solid bitumen at the early oil window(R_(o)=0.73%)and shrinkage cracks were observed.Initial-oil solid bitumen cracked to oil,gas and post-oil bitumen by primary cracking(R_(o)=0.98%).Moreover,solid bitumen(SB)was found to be the dominant OM when R_(o)>0.98%,which indicates that SB is the product of oil-prone macerals transformation.Many secondary bubble pores were observed on SB,which formed by gas release,while devolatilization cracks developed on migrated SB.Additionally,at the late oil window(Ro?1.16%),migrated SB filled the interparticle pore spaces.With further increase in temperature,the liquid oil underwent secondary cracking into pyrobitumen and gas,and spongy pores developed on the pyrobitumen at higher levels of maturity(Ro=1.43%),which formed when pyrobitumen cracked into gas.Vitrinite and inertinite are stable without any visible pores over the range of maturities,verifying their low petroleum generation potential.In addition,it was concluded that clay minerals could have a catalytic effect on the petroleum generation,which may explain why organicclay mixtures had more abundant pores than

关 键 词：Lacustrine shale Maceral evolution Organic pores Scanning electron microscopy Reflected light microscopy 

分 类 号：P618.13[天文地球—矿床学]