In situ Raman spectroscopic quantification of CH4–CO2 mixture: application to fluid inclusions hosted in quartz veins from the Longmaxi Formation shales in Sichuan Basin, southwestern China

作     者：Ye Qiu Xiao-Lin Wang Xian Liu Jian Cao Yi-Feng Liu Bin-Bin Xi Wan-Lu Gao Ye Qiu;Xiao-Lin Wang;Xian Liu;Jian Cao;Yi-Feng Liu;Bin-Bin Xi;Wan-Lu Gao

作者机构：School of Earth Sciences and EngineeringNanjing UniversityNanjing 210023JiangsuChina Ocean CollegeZhejiang UniversityZhoushan 316021ZhejiangChina Wuxi Research Institute of Petroleum GeologySINOPECWuxi 214151JiangsuChina 

出 版 物：《Petroleum Science》 (石油科学（英文版）)

年 卷 期：2020年第17卷第1期

页      面：23-35页

核心收录：

学科分类：081704[工学-应用化学] 081803[工学-地质工程] 07[理学] 08[工学] 0817[工学-化学工程与技术] 0818[工学-地质资源与地质工程] 070302[理学-分析化学] 0703[理学-化学] 

基　　金：financially supported by the National Natural Science Foundation of China(Grant Nos.41922023 and 41830425) the Fundamental Research Funds for the Central Universities(Grant Nos.020614380056 and 020614380078) 

主　　题：Raman spectroscopy Molar ratio Fluid pressure CO2–CH4 mixture Fluid inclusion Paleo-overpressure 

摘      要：We re-evaluate the Raman spectroscopic quantification of the molar ratio and pressure for CH4–CO2 ***,the Raman quantification factors of CH4 and CO2 increase with rising pressure at room temperature,indicating that Raman quantification of CH4/CO2 molar ratio can be applied to those fluid inclusions(FIs)with high internal pressure(i.e.,15 MPa).Secondly,the v1(CH4)peak position shifts to lower wavenumber with increasing pressure at constant temperature,confirming that the v1(CH4)peak position can be used to calculate the fluid ***,this method should be carefully calibrated before applying to FI analyses because large discrepancies exist among the reported v1(CH4)-P curves,especially in the highpressure *** calibrations are applied to CH4-rich FIs in quartz veins of the Silurian Longmaxi black shales in southern Sichuan *** vapor phases of these FIs are mainly composed of CH4 and minor CO2,with CO2 molar fractions from4.4%to 7.4%.The pressure of single-phase gas FI ranges from 103.65 to 128.35 MPa at room temperature,which is higher than previously *** calculations supported the presence of extremely high-pressure CH4-saturated fluid(218.03–256.82 MPa at 200°C),which may be responsible for the expulsion of CH4 to adjacent reservoirs.