Identification and Distribution of Lithologic Reservoirs in Permian Formation, Q Area in Zhunger Basin

Abstract

Taking the Q area in Zhunger Basin for example, reservoirs and traps in the subwater fan in WuTonggou Formation can be identified by sequence stratigraphy, the analysis of seismic attributions and the optimization which can also be used to analyze the oil saturation. Therefore, the region of hydrocarbon can be predicted. The oil source rocks are in the middle of Permian System, and the major reservoirs are in the Upper Permian System. The WuTonggou Formation in upper Permian system can be divided into three parts: LST, TST and HST. Sand bodies of LST are the targets of this research. The subwater apron deposited from east to west. The braided channel in the middle fan is the best reservoir. The resolution was improved by the technology of seismic frequency division, and the strata slices of 40HZ seismic data were proved the best. Obviously, the subwater fan deposited from east and the braided channel changed its location continuously. The major flow direction of braided channel changed from the west to the south. It is also illustrated that the northern part of Q area uplifted and the sedimentary center migrated from northwest to southwest. The original sandstone was sealed by mudstone along with the transfer of braided channel. Therefore, the lithologic traps were updip pinch out, which can be generated because of the uplift of northern part. After the optimization of seismic attributes based on GA-BP, results showed that the areas of high oil saturation were in the west and southwest, especially the reservoirs which were in the southwest had the highest oil saturation.