Characteristics and Differences Analysis for Thermal Evolution of Wufeng–Longmaxi Shale, Southern Sichuan Basin, SW China

The marine shale of the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation is main source rock and target gas exploration in southern Sichuan Basin. maturity organic matter (OM) a vital indicator for evaluation. Due to lack vitrinite, Wufeng–Longmaxi Formations Basin difficult accurately evaluate. In total, 33 core samples were selected observe optical characteristics solid bitumen graptolites measure their random reflectance. Simultaneously, Raman spectroscopic parameters kerogen also used quantitatively analyze change maturity. By using as mediators, conversion equations between graptolite reflectance (GRor) equivalent vitrinite (EqVRo) established. Taking calculation results EqVRo constraints, tectono-thermal evolution history Shale constructed through basin modelling. show that western Changning, Luzhou-western Chongqing, eastern Changning Weiyuan areas decreases successively. falls ranges 3.61%~3.91%, 2.92%~3.57%, 3.08%~3.25%, 2.41%~3.12%, average 3.73%, 3.30%, 3.18% 2.80%, respectively. Thermal was controlled by thermal effect Emeishan mantle plume paleo-burial depth, while other mainly depth. This study provides reliable parameter evaluation makes more accurate calibration Basin; it expounds factors differences different parts area.