| There are significant differences in the total gas content measured in high-quality shale section (TOC≥2.0%) of the Upper Ordovician Wufeng Formation and the Lower Silurian Longmaxi Formation in the Dingshan area of southeastern Sichuan Province. The average gas content of well DY1 is 3.07m3/t, and the average gas content of DY2 is 6.79m3/t. In the study area, the source conditions of the high-quality shale are similar: the total thickness in the early stage of Wufeng Formation-Longmaxi Formation is relatively large, usually between 30m and 35.5m; the average TOC of the shale is almost 3.42%~3.95%; shale thermal evolution is moderate, Ro value is generally greater than 2.0%. The comprehensive study suggests that the preservation conditions are the key factors that contribute to the difference in gas content of shale in Dingshan area. The deep buried area, where is far away from Qiyueshan Fault, is a favorable zone for shale gas reservoirs. While in the area close to Qiyueshan Fault, the shale gas is relatively poor because the lateral dissipation of shale gas is more serious, due to the high angle fractures and the shallow burial of the shale. |
