摘要
过成熟页岩(Ro>2.5%)地层中分布的沥青为残留油裂解后产生的焦沥青,其含量与分布特征能在一定程度上指示页岩残留油的含量。根据演化过程中有机质生排烃特征及C元素的转化关系,建立了根据焦沥青含量恢复过成熟页岩排油效率的方法,并以丁页5井为例,评估了丁山地区龙马溪组页岩的排油效率和晚期生气潜力。结果表明,丁页5井龙马溪组页岩焦沥青面分布率为0.35%~1.31%,整体上与总有机碳(TOC)含量呈正相关关系,估算排油效率为27.7%~75.7%,其中TOC>2%层段的排油效率均大于60%(平均70.7%)。在此基础上,估算丁页5井龙马溪组页岩晚期生气潜力(排油过程之后的实际生气潜力)为1.9~9.2 m^(3)/t(以页岩计算),其中TOC>2%层段的生气潜力均大于4 m^(3)/t,高于页岩气商业开发的含气量下限(3 m^(3)/t),与现今龙马溪组页岩气的开发现状一致,表明通过沥青含量恢复的排油效率以及基于此评估的页岩晚期生气潜力具有一定的指导意义。
Solid bitumen distributed in the over-mature shale(Ro>2.5%)is the pyrobitumen produced by the secondary cracking of residual oil.Thus its content and distribution characteristics can indicate the amount of residual oil.In this study,taking Longmaxi shale from well Dingye 5 as an example,a method is established to assess the oil expulsion efficiency of overmature shale through the pyrobitumen content according to the hydrocarbon generation of organic matter and the organic carbon elements conversion relationship.Then,the oil expulsion efficiency and late gas generation potential of shale in the Dingshan block were evaluated.The results show that the surface distribution rate of pyrobitumen in Longmaxi Shale from well Dingye 5 is positively correlated with TOC content and between 0.35%to 1.31%.Correspondingly,the oil expulsion efficiency of the shales is estimated from 27.7%to 75.7%.On this basis,the estimated late gas generation potential of Longmaxi shale from well Dingye 5 is between 1.9 to 9.2 m^(3)/t shale,in which the gas generation potential of the member with TOC>2%is greater than 4 m^(3)/t shale,higher than the minimum requirement of gas content(3 m^(3)/t shale)for commercial development of shale gas.The above calculation results are consistent with the current development status of Longmaxi shale gas,indicating that the late gas generation potential of overmature shale estimated based on pyrobitumen content and oil expulsion efficiency is objective and meaningful.
作者
李东升
盖海峰
程鹏
李腾飞
樊祺章
孟广明
高平
肖贤明
LI Dongsheng;GAI Haifeng;CHENG Peng;LI Tengfei;FAN Qizhang;MENG Guangming;GAO Ping;XIAO Xianming(School of Energy,China University of Geosciences(Beijing),Beijing 100083,China;State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;CAS Center for Excellence in Deep Earth Science,Guangzhou 510640,Guangdong,China)
出处
《地球化学》
CAS
CSCD
北大核心
2023年第4期416-427,共12页
Geochimica
基金
国家自然科学基金项目(U19B6003-03-01、42030804、42173031)
中石油西南油气田研究院项目(XNS-YYY-JS2021-49)联合资助。
关键词
沥青
排油效率
龙马溪组页岩
生气潜力
bitumen
oil expulsion efficiency
Longmaxi shale
gas generation potential
