摘要
鄂尔多斯盆地二叠系山西组海陆过渡相页岩是重要的页岩气勘探层位,为了深入研究山西组海陆过渡相页岩含气性及气体地球化学特征,选取2口钻井岩芯样品进行了现场解析气量测定、解析气组分和稳定碳同位素分析以及相关有机地球化学分析,认为山西组海陆过渡相页岩具备页岩气生成的良好地质条件.研究结果表明:山西组页岩有机质丰度较高(TOC为1.73%~3.09%),干酪根类型为Ⅲ型,并处于成熟—高成熟演化阶段;解析气中,甲烷体积分数为80.07%~96.29%,平均值为88.79%,甲烷和乙烷的碳同位素值分别介于-49.2‰^-36.9‰和-17.1‰^-15.4‰之间,碳同位素均具有δ^(13)C_1<δ^(13)C_2的正序分布特征,属于有机热成因气;山西组页岩解析气含量平均值为0.38 m3/t,处于已具备页岩气生产能力的四川盆地五峰组—龙马溪组页岩解析气含量范围之内,表明鄂尔多斯盆地山西组海陆过渡相页岩具有较好的页岩气勘探潜力.
Lower Permian Shanxi formation marine-continental transitional shale is one of the most important shale gas exploration beds in Ordos basin. To investigate the shale gas content and its geochemical characteristics, two drilling core samples were selected for test including and its geochemical characteristics, two drilling core samples were selected for test including canister adsorption experiment, chemical components, carbon isotopic compositions and other geochemical analyses. The results show that the Shanxi formation shale has good geological conditions for shale gas generation. It is characterized by high organic content （TOC in the range of 1.73 --3.09%）. The kerogen type is Ⅲ, and is still in the evolution from maturity to over maturity. The volume fraction of methane contained in the desorbed gas ranges from 80. 07% to 96.29%, with an average of 88.79%. The carbon isotopic composition of methane and ethane varies from --49.2‰ to --36. 9‰ and --17. 1‰ to -15.4‰, respectively. The carbon isotope distribution pattern is positive （δ^13 C1〈13 C2）, indicating that the shale gas is thermogenic origin. The average content of the desorbed gas （0.38 m3/t） falls in the range of desorbed gas content of Wufeng-Longmaxi formation in Sichuan basin, which has already had the shale gas production capacity. It is demonstrated that the marine-continental transitional shale of Shanxi formation in Ordos basin has good potential for shale gas exploration.
出处
《中国矿业大学学报》
EI
CAS
CSCD
北大核心
2017年第4期859-868,共10页
Journal of China University of Mining & Technology
基金
中国科学院战略性先导科技专项(XDB10030404
XDB03020405)
国家自然科学基金项目(41572350
41503049)
西部之光一般项目
甘肃省重点实验室项目(1309RTSA041)
关键词
页岩气
海陆过渡相
山西组
含气性
成因类型
鄂尔多斯盆地
shale gas
marine-continental transitional
Shanxi formation
shale gas content
genetic types
Ordos basin
