Reservoir-forming Conditions and Favorable Explora- tion Areas in the Southeast of Tazhong Uplift

An analysis of the evolution of the sedimentary structures in Tazhong area shows that the Tazhong uplift is a structural uplift that experienced multiphase tectonic activities from the end of Early Ordovician to the time when the Donghe Formation sandstones deposited. Source rocks of Lower Paleozoic with high quality developed in Tang-guziba sag to the south of the uplift. Erosion action and karstification that resulted from multiple structural uplifting and strong faulting and folding provided favorable conditions for the development of karst reservoirs of Ordovician and the formation of local structures. In comparison with the reservoirs that have been discovered in Tazhong area, the local structures in the southeast of Tazhong area formed earlier and had good trap types and 4 sets of important reservoir - seal combinations, thus the reservoir - forming conditions are good.