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, Longhui Bai, Mehdi Ostadhassan, Thomas Gentzis, Boyang Wang, Yi-Zhang Wang · 发表于：Petroleum Science · 年份：2023 · DOI：10.1016/j.petsci.2023.08.025 · 被引用次数：29 · 研究领域：Hydrocarbon exploration and reservoir analysis、Petroleum Processing and Analysis、Atmospheric and Environmental Gas Dynamics

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 (Ro) 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 (Ro = 0.58%). As a result of petroleum generation, oil-prone macerals began to transform to initial-oil solid bitumen at the early oil window (Ro = 0.73%) and shrinkage cracks were observed. Initial-oil solid bitumen cracked to oil, gas and post-oil bitumen by primary cracking (Ro = 0.98%). Moreover, solid bitumen (SB) was found to be the dominant OM when Ro > 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 interp...