THE YANQI COMPRESSIONAL-THRUST RESIDUAL BASIN IN XINJIANG PROVINCE AND ITS OIL-GAS EXPLORATION

In this article, the Yanqi Basin was divided into three structural deformation regions from south to north-southern decollement nappe region, central thrust folded region and northern strike-slip adjustment region according to the characteristics of inherited compressional inverse deformation getting strengthened from north to south in the Mesozoic Yanqi Prototype Basin during the Yanshanian and the Ximalayan periods. The compressional structures with NWW trend (close to EW trend) and the shear structures with NW trend crossed each other to form a "lozenge grid" structural pattern. The distribution features of secondary structural belts and local structures were controlled by this structural pattern. On the basis of structural and depositional distribution in the south and north depressions of the prototype basin, the zonation was further strengthened through paulopost reformation, and the north and south paleogeothermal field regions and the relatively independent petroleum systems were formed. In the residual basin, it created different oil-controlling structural combinations and different oil-gas accumulation patterns due to its three basic and unique deformation styles. Based on the reformation styles and pool-forming characteristics of the residual basin, it was predicted that the pool-forming units of "inheritance and regeneration" and "reformation and regeneration" in the northern depression were the favorable regions to discover reserves recently.