天然气勘探与开发2025，Vol.48Issue(6)：30-40,11.DOI:10.12055/gaskk.issn.1673-3177.2025.06.003
高—过成熟海相页岩有机质热演化成熟度评价方法适用性对比
Applicability comparison of methods for evaluating the thermal maturity of organic matter in highly-to over-mature marine shales:A case study of the Wufeng-Longmaxi Formations in western Chongqing Area
摘要
Abstract
The Lower Paleozoic marine shales in Sichuan Basin are characterized by ancient age,lack of vitrinite,and high degree of thermal evolution of organic matter,which limit the applicability of traditional organic matter maturity evaluation methods.To accurately characterize the thermal evolution degree of organic matter in the shales from the Upper Ordovician Wufeng Formation to the Lower Silurian Longmaxi Formation(Wufeng-Longmaxi Formations)in western Chongqing,a systematic comparison was made between microphotometry and laser Raman spectroscopy on their respective applicability for determining the thermal maturity of organic matter in over-mature shales.Results show that(i)both methods suggest that the organic matter in the Wufeng-Longmaxi Formations in western Chongqing is in the over-mature stage;(ii)the equivalent vitrinite reflectance values calculated by microphotometry show significant data discreteness due to the compositional complexity of solid bitumen,multi-stage origins,and optical anisotropy.These values are also susceptible to mineral matrix interference and regional differences in empirical formulas,leading to systematic underestimates;(iii)the maturity data calculated based on the peak height ratio from peak-fitting exhibit high concentration and small errors,indicating that this method is capable of micro-area analysis,less affected by sample heterogeneity,and able to achieve an in-situ capture of the graphitization characteristics of organic matter.Therefore,the evolution degree of organic matter in highly-to over-mature shales is more accurately characterized.It is concluded that laser Raman spectroscopy outperforms microphotometry in terms of accuracy,stability,and anti-interference,and it is preferred for evaluating the thermal maturity of organic matter in over-mature marine shales without vitrinite.关键词
四川盆地渝西区块/奥陶系上统五峰组/志留系下统龙马溪组/固体沥青反射率/有机质成熟度/激光拉曼光谱Key words
Western Chongqing area of Sichuan Basin/Upper Ordovician Wufeng Formation/Lower Silurian Longmaxi Formation/Solid bitumen reflectance/Thermal maturity of organic matter/Laser Raman spectroscopy分类
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蒲俊伟,梁静怡,张海杰,牟泳澄,尤静仪,梁霄..高—过成熟海相页岩有机质热演化成熟度评价方法适用性对比[J].天然气勘探与开发,2025,48(6):30-40,11.基金项目
四川省自然科学基金面上项目"川西南下寒武统筇竹寺组页岩成脉流体活动与页岩气成藏过程"(编号:2025ZNSFSC0310). （编号:2025ZNSFSC0310）
