Genetic mechanism and evolutionary pattern of pore structure in deep marine shales in Sichuan Basin, South China: Insights from SEM observation and quantitative characterization

Genetic mechanism and evolutionary pattern of pore structure in deep marine shales in Sichuan Basin, South China: Insights from SEM observation and quantitative characterization | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Genetic mechanism and evolutionary pattern of pore structure in deep marine shales in Sichuan Basin, South China: Insights from SEM observation and quantitative characterization Xueying Wang, Kun Zhang, Shu Jiang, Yan Song, Lin Jiang, Xinyang He, and 10 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4508072/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study addresses gaps in research on the pore structures of deep, organic-rich marine shales, focusing on the lower Silurian Longmaxi Formation in Sichuan's Luzhou Block, using wells L1 and L2. Employing techniques like organic geochemistry, mineral composition analysis, CO 2 and N 2 adsorption-desorption, high-pressure mercury intrusion, FIB-SEM, and NMR, the study identifies pyrobitumen as the main pore contributor, accounting for approximately 59.95%-62.00% of pores. It documents a reduction in pore storage and connectivity from the over-mature to semi-graphitised stages, with mesopores showing a smaller decline (8.37%-9.14%) compared to micropores and macropores (25.02%-52.86%). Additionally, connectivity of 100–1000 nm pores decreased significantly (33.46%-62.09%). Changes in the stages of maturity affected the pore characteristics: retained oil in mature stages transformed into pyrobitumen, reducing surface porosity. In the over-mature stage, diagenesis and thermal evolution led to gas-filled pyrobitumen pores which balanced with formation pressures to preserve pore structure. The semi-graphitised stage saw a significant reduction in pore volume and surface porosity due to compaction and carbonization. Earth and environmental sciences/Solid earth sciences/Geology Physical sciences/Energy science and technology/Fossil fuels/Natural gas Deep marine shale Longmaxi Formation Pore structure Quantitative characterization Genetic mechanism Evolutionary pattern Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4508072","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":314176297,"identity":"c8faeb54-1711-4ef6-b56b-b3378db05021","order_by":0,"name":"Xueying Wang","email":"","orcid":"","institution":"Southwest Petroleum University","correspondingAuthor":false,"prefix":"","firstName":"Xueying","middleName":"","lastName":"Wang","suffix":""},{"id":314176300,"identity":"34896055-2cf9-4308-9800-33ad350851ce","order_by":1,"name":"Kun 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