Analysis of Influencing Factors of Poisson’s Ratio in Deep Shale Gas Reservoir Based on Digital Core Simulation

Abstract

Conventional petrophysical experiments in deep shale gas reservoirs are characterized by difficult coring, high cost, and insufficient representative samples, so it is difficult to comprehensively investigate the key factors of Poisson’s ratio through petrophysical experiments. In this study, a multiscale and multicomponent three-dimensional (3D) digital core was constructed for the shale gas reservoir of Wufeng Formation-Longmaxi Formation in the Dazu area, Western Chongqing, China, to quantitatively simulate the influences of the changes of reservoir gas saturation, mineral composition, stratification, and fractures on Poisson’s ratio. The absolute errors between Poisson’s ratio measured by core experiments, Poisson’s ratio simulated by the multiscale and multicomponent digital core, and Poisson’s ratio calculated with the time differences of longitudinal and transverse waves were analyzed. The analysis results showed that Poisson’s ratio was sensitive to stratification dip angle and fracture dip angle. When the stratification dip angle or fracture dip angle was close to 45°, Poisson’s ratio reached its minimum value. Poisson’s ratio was more sensitive to the content of calcite than the contents of quartz, dolomite, and pyrite. The influence of gas saturation on Poisson’s ratio was the least. The average error between Poisson’s ratio measured by core experiments and Poisson’s ratio simulated by the multiscale and multicomponent digital core was 4.920%. The average error between Poisson’s ratio measured by core experiments and Poisson’s ratio calculated with the time differences of longitudinal and transverse waves was 10.968%.