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 LIU Bo;WANG Liu;FU Xiaofei;HUO Qiuli;BAI Longhui;LYU Jiancai;WANG Boyang

作者机构：National Key Laboratory of Continental Shale OilNortheast Petroleum UniversityDaqing163318China Exploration and Development Research Institute of PetroChina Daqing Oilfield Company LimitedDaqing 163712China 

出 版 物：《Petroleum Exploration and Development》 (石油勘探与开发（英文版）)

年 卷 期：2023年第50卷第6期

页      面：1345-1357页

核心收录：

学科分类：0820[工学-石油与天然气工程] 081803[工学-地质工程] 08[工学] 0708[理学-地球物理学] 0818[工学-地质资源与地质工程] 

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

主　　题：shale solid bitumen reflectance primary maceral difference solid bitumen evolution path reservoir space Songliao Basin Cretaceous Qingshankou Formation 

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.