Shale gas content evolution in the Ordos Basin

Abstract

Abstract Gas content is a crucial parameter for shale reservoir evaluation and shale gas accumulation. Taking Shanxi and Taiyuan Formation shale samples from the Ordos Basin of China as an example, this research used thermal simulation, Rock-Eval pyrolysis, total organic carbon content (TOC) measurement, vitrinite reflectance (Ro) measurement, X-ray diffraction analysis, and methane isothermal adsorption based on formation conditions to study the evolution of shale gas content. A thermogenic gas content model was established through thermal simulation, Rock-Eval pyrolysis, and Ro measurement, while the influential factors of adsorbed gas content were analysed and a model was established through TOC and Ro measurements, X-ray diffraction analysis, methane isothermal adsorption, and reservoir conditions. Then, the research characterized the evolution of thermogenic gas, gas-in-place (GIP), adsorbed gas, and free gas through geologic time using a combination of thermogenic gas content, hydrocarbon expulsion and adsorbed gas content models.