Author Identifier
Yujie Yuan: https://orcid.org/0000-0003-3931-2071
Stefan Iglauer: https://orcid.org/0000-0002-8080-1590
Document Type
Journal Article
Publication Title
International Journal of Coal Geology
Volume
295
Publisher
Elsevier
School
School of Engineering
RAS ID
77874
Funders
National Natural Science Foundation of China (42302162) / Natural Science Foundation of Yunnan Province (202401AT070435, 202201AU070041) / China National Petroleum Corporation CNPC international cooperation project (2021DQ-0405) / CNPC Scientific Project (2024ZZ-01) / National Overseas Top Talents Program (JXRSB02001)
Abstract
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 CO2/N2 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, therefore, provides new insights into identifying the most favorable shale gas resources. This knowledge assists in accurate predictions of the stratigraphic ‘sweet spot’ intervals for large shale gas storage capacity, providing crucial information for engineering explorations and developments in shale formations.
DOI
10.1016/j.coal.2024.104638
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Yuan, Y., Wu, S., Al-Khdheeawi, E. A., Tan, J., Feng, Z., You, Z., Rezaee, R., Jiang, H., Wang, J., & Iglauer, S. (2024). Substantial gas enrichment in shales influenced by volcanism during the Ordovician–Silurian transition. International Journal of Coal Geology, 295. https://doi.org/10.1016/j.coal.2024.104638