Quantitative Comparison of Genesis and Pore Structure Characteristics of Siliceous Minerals in Marine Shale With Different TOC Contents–A Case Study on the Shale of Lower Silurian Longmaxi Formation in Sichuan Basin, Southern China

China has abundant shale gas resources with great exploration potential, and stage progress been made in this aspect. The sedimentary environment reservoir characteristics are important aspects of the study on accumulation. Previous studies have mostly carried out from a “qualitative” perspective, but not “quantitative” one. There is lack comparative “marine shales different TOC contents”. This paper takes marine first member Longmaxi Formation (Long 1 Fm) southern Sichuan Basin, Southern China, as research object. core samples were taken to carry analyses (mineral composition analysis, content porosity analysis) experiments (carbon dioxide nitrogen adsorption experiments, high-pressure mercury intrusion, FIB-SEM, FIB-HIM experiments). element logging data collected conduct quantitative comparison genesis pore structure siliceous minerals contents area. conclusions follows: first, formula used calculate determine whether there excessive silicon; then Al-Fe-Mn triangle diagram analyze silicon, so quantitatively shale: organic (1% < <2%) studied almost terrigenous detrital genesis; most organic-rich (TOC >2%) genesis, small part (0–20%) biogenic. Carbon well intrusion adopted characterize whole-aperture characteristics. development components analyzed by combing FIB-SEM experiments. organic-bearing target section area mainly develop clay mineral pores (71%), dominated macro-pores (57.3%) low number pores, irregular-shaped poor storage capacity connectivity; (51%), micro-pores (32.1%) mesopores (54%) that large elliptical-shaped, good connectivity. results help improve understanding size shales, origin which theoretical practical significance for improving theory formation guiding selection sweet spot.