Enrichment conditions and distribution characteristics of lacustrine medium-to-high maturity shale oil in China
作者机构：Research Institute of Petroleum Exploration and DevelopmentCNPCBeijing 100083China Key Laboratory of Oil and Gas ReservoirsCNPCBeijing 100083China ZWZ Academician Research StudioBeijing 100083China
出 版 物：《地学前缘》 (Earth Science Frontiers)
年 卷 期：2023年第30卷第1期
页 面：242-259页
核心收录：
学科分类：081803[工学-地质工程] 08[工学] 0818[工学-地质资源与地质工程]
基 金：Major Project of National Natural Science Foundation of China(42090020,42090025) Major Project of CNPC(2019E-2601)
主 题：medium-to-high maturity shale oil sweet-spot zone enrichment conditions distributional characteristics assessment standard onshore China
摘 要：Successful breakthroughs have been made in shale oil exploration in several lacustrine basins in China,indicating a promising future for shale oil exploration and *** exploration results have revealed the following major conditions of lacustrine shale oil accumulation:(1)stable and widely distributed shale with a high organic abundance and appropriate thermal maturity acts as a fundamental basis for shale oil *** shale exhibits several critical parameters,such as total organic carbon content greater than 2%,with optimal values ranging from 3% to 4%,kerogen Ⅰ and Ⅱ_(1) as the dominant organic matter types,and vitrinite reflectance(R_(o))values greater than 0.9%(0.8% for brackish water environments).(2)Various types of reservoirs exhibiting brittleness and a certain volume of micro-nanoscale pores are critical conditions for shale oil accumulation,and these reservoirs have porosities greater than 3% to 6%.Moreover,when diagenesis is incipient,pure shales are not favorable for medium-to-high maturity shale oil enrichment,whereas tight sandstone and hybrid rocks with clay content less than 20% are favorable;however,for medium-to-late-stage diagenesis,pure shales with a clay content of 40% are favorable.(3)The retention of a large amount of high-quality hydrocarbons is the factor that best guarantees shale oil accumulation with good *** hydrocarbon content exceeding a threshold value of 2 mg/g is generally required,and the optimum value is 4 mg/g to 6 mg/***,a gas-oil ratio exceeding a threshold value of 80 m^(3)/m^(3) is required,with the optimal value ranging from 150 m^(3)/m^(3) to 300 m^(3)/m^(3).(4)High-quality roof and floor sealing conditions are essential for the shale oil enrichment interval to maintain the overpressure and retain a sufficient amount of hydrocarbons with good *** shale oil distributions exhibit the following characteristics:(1)major enrichment areas of shale oil are located in semi-deep t
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