Pore Structure Characteristics of the Jurassic Dongyuemiao Shale Reservoir in the Fuxing Area, Sichuan Basin
DOI:
https://doi.org/10.54097/8c7xwn37Keywords:
Pore structure; shale reservoir; Jurassic; Sichuan Basin.Abstract
XRD analysis reveals that the shale mineral composition in the study area is dominated by clay minerals (15.21%–79.68%, avg. 59.88%), primarily illite, with subordinate chlorite and kaolinite, followed by quartz (10.24%–45.84%, avg. 21.59%). Total organic carbon (TOC) ranges from 0.391% to 2.19%, with kerogen types predominantly sapropelic-humic (Type II₂) and humic (Type III). Vitrinite reflectance (R₀ = 1.52%–1.54%) indicates high thermal maturity. Pore systems are dominated by parallel-plate interlayer clay pores, supplemented by calcite intraparticle pores, interparticle pores, and organic-hosted pores. Based on pore size classification, mesopores (2–50 nm) contribute the largest proportion to total pore volume, followed by macropores (>50 nm) and micropores (<2 nm). The influence of mineralogy and TOC on pore structure varies by lithofacies: in clay-rich shales, clay minerals and TOC synergistically enhance pore development, while in silty shales, quartz content exhibits a positive correlation with pore volume, likely due to grain-supported frameworks preserving primary porosity.
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