Oiliness gradation of hybrid sedimentary shale with low-moderate organic matter content:a case study of the Paleocene Shahejie Formation in Dongpu Depression,Bohai Bay Basin
Zhiming Xiong1
Tao Hu1
Yuqi Wu1
Yunlong Xu2
Jiyou Fu3
Huiyi Xiao1
Yuan Liu1
Kuo Zhou1
Qinglong Lei1
Tianshun Chen1
Xiaofei Lin1
Mingxing Liu1
Shu Jiang4
Maowen Li5
1.State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China2.Exploration and Development Research Institute,Zhongyuan Oilfield Company,SINOPEC,Puyang 457001,China3.Changqing Oilfield Shale Oil Development Branch,Xi'an 745000,China4.Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences),Ministry of Education,Wuhan 434100,China5.State Key Laboratory of Shale Oil and Shale Gas Resources and Effective Development,Sinopec Petroleum Exploration and Production Research Institute,Beijing 100083,China
摘要：Shale oil resources are abundant on Earth,of which hybrid sedimentary shale(HSS)oil is an important component,includ-ing high and medium-low organic matter content(TOC).Oil content,especially the oiliness gradation,is a key parameter for shale oil evaluation and numerous studies had been conducted.However,most studies concentrated on the HSS with high TOC,making oil content evaluation of the HSS with medium-low TOC challenging.The Paleocene Shahejie Forma-tion(E2s)shale in Dongpu Depression is a typical HSS with low-moderate TOC,showing great shale oil resource potential.Integrated geochemical characterization of 270 core samples were conducted and results show that,the E2s shale has fair-good hydrocarbon generation potential,with TOC ranging from 0.06％ to 3.6％(Avg.0.86％)and Ⅱ1-Ⅱ2 kerogen type in thermally mature.The hydrocarbon generation potential decreases with kerogen types changing from type Ⅰ to Ⅲ,but S1C and the oil saturation index(OSI)(S1*100/TOC＞100)increase from type Ⅰ to Ⅱ1,and then decrease from type Ⅱ2 to Ⅲ,indicating shale with type Ⅱ2 kerogen have the greatest oil content.This is related to the differences in hydrocarbon expul-sion efficiency caused by differential hydrocarbon generation potential and pore-microfractures evolution among shales with different kerogen types.Significant oil micro-migration occurred in E2s shale,with micro-migration quantity(ΔQ)ranging from-846 to 993 mg/g(Avg.-120 mg/g),and 90％and 10％shale exhibit hydrocarbon intra-micro-migration(ΔQ＜0)and extra-micro-migration(ΔQ＞0).The shale with type Ⅱ2 kerogen has the greatest intra-micro-migration.Based on S1C,TOC and OSI values and their evolution pattern,shale oil resources were classified into enriched,moderately enriched,less efficient and invalid resources,accounting for 11％,53％,16％and 21％respectively,with S1C thresholds of 3.5 and 0.5 mg/g,OSI threshold of 100 mg/g.Compared with previous grading criteria,the gradation criterion established in this study is relatively lower,which is mainly due to the lower TOC and clay mineral content in HSS.Enriched and moderately enriched resources are mainly shales with type Ⅱ2 kerogen,followed by type Ⅱ1 kerogen,and the E2s4U and E2s3L shale are the most favorable targets for further shale oil exploration.The established oiliness gradation criteria are applicable for the HSS with TOC in other parts of the world.
机标关键词：depressioncontentshaleorganichybridstudycasewith
论文发表日期：2025-10-31
在线出版日期：2026-01-31（本平台首次上网日期，不代表文献的发表时间）
页数：19( 199-217 )
英文信息