Abstract To study the occurrence state and content of shale gas in different depositional environments, 15 marine shale samples from Longmaxi Formation in the Sichuan Basin and 15 continental shale samples from Yanchang Formation in the Ordos Basin were sampled. Then a series of experiments, including X-ray diffraction analysis, TOC content analysis, Ro measurement, NMR measurements, FE-ESEM observation, low-pressure N2 adsorption, and CH4 isothermal adsorption were conducted. In general, shale gas in Yanchang formation has the characteristics of primary adsorbed gas, moderate free gas, and non-ignorable dissolved gas, whereas shale gas in Longmaxi formation has the characteristics of joint dominated free gas and adsorbed gas, as well as negligible dissolved gas. Both macroscopic accumulation pattern and microscopic occurrence model show four stages in the whole thermal evolution, that is, adsorption, pore filling, fracture filling and accumulation. By analyzing the affecting factors of shale gas adsorption, conclusions can be drawn that geological characteristics, mineral compositions, pore structure features and formation conditions have influence on adsorbed gas content to various degrees. Cause analyses reveal that differences in occurrence state and gas content between marine and continental shales are immediately affected by the differences of organic matter type, thermal maturity, brittle minerals content, carbonate content, SSA, PD, porosity, gas saturation, residual oil quantity, as well as T&P, indirectly controlled by sedimentary environment and tectonic movement.

中文翻译：

---

海陆相页岩赋存特征及含气量分析——龙马溪组与延长组对比研究

摘要 为研究不同沉积环境下页岩气的赋存状态和含量，采集了四川盆地龙马溪组海相页岩15个和鄂尔多斯盆地延长组陆相页岩15个样品。然后进行了一系列实验，包括X射线衍射分析、TOC含量分析、Ro测量、NMR测量、FE-ESEM观察、低压N2吸附和CH4等温吸附。总体而言，延长组页岩气具有原生吸附气、中等游离气、不可忽视的溶解气特征，而龙马溪组页岩气具有游离气和吸附气联合主导、可忽略的溶解气特征。气体。宏观成藏模式和微观赋存模式均表现为整个热演化过程中经历吸附、孔隙充填、裂缝充填和成藏四个阶段。通过分析页岩气吸附的影响因素，可以得出地质特征、矿物成分、孔隙结构特征和地层条件对吸附气含量有不同程度影响的结论。成因分析表明，海相页岩与陆相页岩赋存状态和含气量的差异直接受到有机质类型、热成熟度、脆性矿物含量、碳酸盐含量、SSA、PD、孔隙度、含气饱和度、剩余油量、以及受沉积环境和构造运动间接控制的 T&P。