Formation conditions and enrichment model of retained petroleum in lacustrine shale: A case study of the Paleogene in Huanghua depression, Bohai Bay Basin, China

• 作者: ZHAO Xianzheng ZHOU Lihong PU Xiugang JIN Fengming SHI Zhannan HAN Wenzhong JIANG Wenya HAN Guomeng ZHANG Wei WANG Hu MA Jianying
• 来源期刊: 石油勘探与开发:英文版
• 学科: 地球科学
• 关键词: lacustrine shale retained hydrocarbon movable hydrocarbon shale oil enrichment model Kong 2 Member Sha 3 Member Huanghua Depression Bohai Bay Basin
• 年，卷（期）: 2020,（5）
• 页码范围: 916-930
• 页数: 15页
• 分类号: P618.13

摘要

Compared with marine facies shale strata,lacustrine shale strata are more complicated in geological conditions,and thus more difficult to explore and develop.To realize economic exploration and development of lacustrine shale oil,the geological regularities of accumulation and high yield of retained movable petroleum in shale should be understood first.In this work,taking the shale strata of Kong 2 Member and Sha 3 Member in the Paleogene of Huanghua depression in the Bohai Bay Basin as examples,based on the previous joint analysis results of over ten thousand core samples and the latest oil testing,production test and geochemical data of more than 30 horizontal wells,accumulation conditions and models of retained movable petroleum in lacustrine shale were studied comprehensively.The study shows that at moderate organic matter abundance(with TOC from 2%to 4%),shale strata have the best match between oil content and brittleness,and thus are rich in oil and good in fracability.Moderate ancient lake basin size and moderate sediment supply intensity are the internal factors leading to best coupling of organic matter abundance and brittle mineral content in the shale formation.Moderate thermal evolution maturity of Ro of 0.7%–1.0%(at burial depth of 3200 to 4300 m)is the interval where oil generation from thermal evolution and oil adsorption by kerogen in shale layers match best,and retained movable petroleum is high in proportion.Moderate diagenetic evolution stage(3200 to 4300 m in the middle diagenetic stage A)is conducive to the formation of a large number of dissolved pores and organic matter pores,which provide storage space for shale oil enrichment.Moderate development degree of natural fractures(without damaging the shale oil roof and floor sealing conditions)is conducive to the storage,seepage and preservation of shale oil.The research results have overthrown the general understanding that high organic matter abundance,high maturity,and high development degree of natural fractures are conducive to shale oil