Substantial gas enrichment in shales influenced by volcanism during the Ordovician–Silurian transition

作者：Yujie Yuan, Songtao Wu, Emad A. Al‐Khdheeawi, Jingqiang Tan, Zhuo Feng, Zhenjiang You, Reza Rezaee, Han Jiang, Jun Wang, Stefan Iglauer · 发表于：International Journal of Coal Geology · 年份：2024 · DOI：10.1016/j.coal.2024.104638 · 被引用次数：5 · 研究领域：Hydrocarbon exploration and reservoir analysis、Geological Studies and Exploration、Methane Hydrates and Related Phenomena

The substantial gas enrichment in shales of the Ordovician–Silurian transition is associated with the development of the organic matter (OM)-rich source rock. While organic matter enrichment has been linked to intensive volcanism, it remains a challenge to precisely evaluate the impact of the volcanism on substantial gas enrichment containing the largest gas storage capacity. This study focused on consecutive borehole shale samples from the Wufeng–Longmaxi formations during the Ordovician–Silurian transition in southern China. We conducted a comprehensive analysis, integrating the major geological volcanism with high-resolution analysis, including QEMSCAN, argon-ion SEM, thin-section examination, XRD mineralogy, TOC, Hg concentration, petrophysical properties and nanopore structure analysis (low-pressure CO 2 /N 2 gas adsorption, helium porosity and permeability). The results link the significant shale gas enrichment in Wufeng–Longmaxi formations to intensive volcanism across the Ordovician–Silurian transition. We identified the most favorable shale intervals in the lower Longmaxi Formation, aligning with the peak period of volcanism. This period showed synchronous spikes in Hg, Hg/TOC, and TOC contents. Shale deposited during this favorable paleoenvironment exhibited the highest values of TOC, porosity, permeability, specific surface area, pore volume, and maximum gas adsorption capacity, leading to the largest amount of gas content and substantial gas enrichment. Our work, ...