Relationship between High Permeability Zones and Palaeostructures in Tight Gas Reservoirs
致密砂岩气藏高渗透带与古构造关系探讨—以川中川南过渡带内江—大足地区上三叠统须二段致密砂岩气藏为例

Research of the T3x^2 tight gas reservoir of Neijiang-Dazu Region in the transitional zone of Chuanzhong and Chuannan reveals that high capacity wells are in zonal distribution and are closely related to palaeostructures. In the process of deposition, because of the water bodies with high-energy on both sides of the palaeotectonic belt, the higher maturity coarse particles were deposited. In the diagenesis, cracks were formed by differential compaction. These make the top and two wings of the palaeotectonic belt to be favorable oil and gas accumulation zones. Due to the relatively poor conditions of sedimentation and diagenesis away from the palaeotectonic belt, physical properties of the reservoirs became poor, so that a lithologic reservoir was formed on the palaeotectonic belt.