Comprehensive analysis of reservoir comparison and controls on pore structure in the Wufeng-Longmaxi shale, Southern...

Significant variations in depositional environments, reservoir conditions, and burial depths across the Yuxi, Luzhou, Changning, and Zhaotong areas, this study investigates the reservoir heterogeneity and pore structure controls in Sichuan Basin's Wufeng-Longmaxi shales. This paper studys the reservoir characteristics of four typical shale exploration areas, by using XRD, FE-SEM and low-temperature N₂ adsorption experiments. The main controls on pore structure were then selected using the grey correlation algorithm. High-quality shale reservoirs consistently develop at the base of the Longmaxi Formation. However, excessive thermal maturity causes degradation of hydrocarbon generation potential and storage capacity in localized areas. There is a strong correlation between pore structure and TOC content (correlation coefficient: 0.72-0.76), Ro (0.73-0.74), tectonics (0.65-0.71), and burial depth (0.23-0.63). Pore structure parameters exhibit a strong positive correlation with TOC content. Pore systems undergo a six-stage evolutionary progression with advancing thermal maturity. In structurally compromised anticlines, pore networks develop directional slit-shaped configurations with reduced pore volumes and surface areas, while excessive burial depth similarly causes reduction in these two parameters. This paper is crucial for improving an understanding of the shale pore system and facilitating the efficient development of shale gas resources.