油气地质与采收率2025，Vol.32Issue(5)：35-45,11.DOI:10.13673/j.pgre.202408002
湖相页岩的解吸特征及其对气体运移的指示
Desorption characteristics of lacustrine shale and its indication for gas migration:A case study of Chang 7 shale in central Ordos Basin
摘要
Abstract
The extensive desorption experiments conducted on shale have promoted research in the fields of shale gas components and carbon isotopes,but the research on identifying gas migration through gas components is still relatively weak.This study focused on the shale in the seventh member of the Triassic Yanchang Formation(Chang 7 shale)in the central Ordos Basin and conducted comparative desorption experiments to explore the gas components and carbon isotopes in the shale by systematically collecting shale samples from different structural areas.In combination with the regional geological background,a detailed analysis of the controlling factors of gas migration was conducted,and the migration patterns of shale gas were clarified,providing a reference for the research on gas migration.The research results show that the organic matter abundance of the Chang 7 shale in the study area is high,and the hydrocarbon generation capacity is strong.The average values of total organic carbon content,free hydrocarbon content,and pyrolysis hydrocarbon content are 4.10%,3.29 mg/g,and 6.43 mg/g,respectively.The volume of desorbed gas is relatively low,with an average value of 1.39 m3/t.Through systematic analysis of the characteristics of the desorbed gas components,it is found that Chang 7 shale gas is oil-type gas,and it is pyrolysis gas originating from kerogen.Based on the strength of the migration process,the Chang 7 shale gas can be divided into three types:in-situ generated gas,in-situ residual gas,and migrated and accumulated gas.In-situ generated gas is mainly stored in the shale reservoirs within the hydrocarbon generation center zone that have not undergone significant migration.It has the characteristics of high desorption gas content,low N2 content,high CO2 content,and heavy carbon isotopes.The migrated and accumulated gas is concentrated in the high parts of the structure or near the fault zones,presenting characteristics such as low desorbed gas content,high N2 content,low CO2 content,and light carbon isotopes.In-situ residual gas lies between in-situ generated gas and migrated accumulated gas and is mainly distributed in the transitional area around the hydrocarbon generation center.关键词
湖相页岩/页岩气/解吸特征/运移/鄂尔多斯盆地Key words
lacustrine shale/shale gas/desorption characteristic/migration/Ordos Basin分类
能源科技引用本文复制引用
戴欣洋,师良,范柏江..湖相页岩的解吸特征及其对气体运移的指示[J].油气地质与采收率,2025,32(5):35-45,11.基金项目
国家自然科学基金项目"陆相页岩岩性非均质性及其对油气滞留的影响"(41702136). （41702136）
