Identification, evolution and geological indications of solid bitumen in shales: A case study of the first member of Cretaceous Qingshankou Formation in Songliao Basin, NE China  

作　　者：LIU Bo WANG Liu FU Xiaofei HUO Qiuli BAI Longhui LYU Jiancai WANG Boyang 

机构地区：[1]National Key Laboratory of Continental Shale Oil,Northeast Petroleum University,Daqing,163318,China [2]Exploration and Development Research Institute of PetroChina Daqing Oilfield Company Limited,Daqing 163712,China

出　　处：《Petroleum Exploration and Development》2023年第6期1345-1357,共13页石油勘探与开发（英文版）

基　　金：Supported by the the National Natural Science Foundation of China(U22A201550).

摘　　要：On the basis of sorting out current understanding of solid bitumen (SB) in shales and taking organic-rich shales in the first member of the Cretaceous Qingshankou Formation in the Songliao Basin as an example, the definition, classification, occurrence and evolution path of SB are systemtically studied, and the indicative significance of SB reflectance (Rob) on maturity and its influence on the development of reservoir space are discussed and summarized. The results show that the difference of primary maceral types is primarily responsible for the different evolution paths of SB. Most of the pre-oil bitumen is in-situ SB with only a small amount being of migrated SB, while most of the post-oil bitumen and pyrobitumen are migrated SB. From the immature to early oil maturity stage, bituminite, vitrinite, and inertinite can be distinguished from SB based on their optical characteristics under reflected light, and alginite can be differentiated from SB by their fluorescence characteristics. Under scanning electron microscope, in-situ SB and migrated SB can be effectively identified. Rob increases linearly with increasing vitrinite reflectance (Ro), as a result of a decrease of aliphatic structure and the enhancement of aromatization of SB. Within the oil window three types of secondary pores may develop in SB, including modified mineral pores, devolatilization cracks and bubble holes. At a high maturity stage spongy pores may develop in pyrobitumen. Scanning electron microscopy combined with in-situ SEM-Raman spectroscopy can further reveal the structral information of different types of SB, thus providing crucial data for understanding for understanding OM migration paths, dynamics, and distances at micro-scale.

关 键 词：shale solid bitumen reflectance primary maceral difference solid bitumen evolution path reservoir space Songliao Basin Cretaceous Qingshankou Formation 

分 类 号：P618.13[天文地球—矿床学]