Geochemical tracing of tight gas migration in Xujiahe Formation in central Sichuan Basin

The research on the accumulation of tight gas has attracted much attention in recent years,and whether nat-ural gas can move in large volumes in a tight reservoir is one of research focuses. In this paper,from the perspective of natural gas geochemistry,the typical tight gas reservoirs in the Xujiahe Formation in central Sichuan are studied to an-swer the question of whether natural gas can be transported in a large scale in tight reservoirs,using the natural gas component parameters. Horizontally,the Xujiahe Formation gas reservoirs are widely distributed intermittently,and ver-tically,multiple gas reservoirs are superimposed. Studies have shown that in the horizontal direction,there are signifi-cant differences in natural gas component parameters,and no horizontal migration of natural gas in the same layer be-tween adjacent gas fields. Vertically,there are significant differences in the geochemical characteristics of natural gas between the upper and lower gas reservoirs in the Xujiahe Formation. This difference does not meet the law of natural gas migration and fractionation,indicating that there has been no significant vertical migration of natural gas. In other words,the tight gas in the Xujiahe Formation is formed in situ or at close range,and has not undergone large-scale mi-gration.