APPLICATION OF DOUBLE-WIDTH SEISMIC DATA TO FRACTURE PREDICTION IN R GASFIELD OF XIHU SAG

Seismic data acquired from the R Gasfield of the Xihu Sag is poor in quality due to its deep buried depth and the conventional seismic data processing is not efficient enough to meet the requirement of exploration. In 2016, high-quality double-width seismic data were acquired with the method of variable-depth atreamer broadband and multi-vessel wide-azimuth acquisition. Because the oil reservoir below the Layer H7 in the R Gasfield is controlled by fractures, the accuracy of fracture prediction is of significance to the production of oil and gas from the reservoirs below the Layer H7. In the past, the fracture prediction could only be performed with seismic attributes and seismic coherent bodies, and the accuracy was often not so high. By using double-width seismic data to predict fracture now, we can get more accurate anisotropy factor and the distribution of fracture density, which can be used to indicate the development status and direction of fractures. The prediction results prove that the fractures are well developed below the Layer H7, and the extending direction of the fractures is consistent with that of the large fault. Fractures in the Layer H11 are more developed than those in the Layer H8, which can well explain why the productivity of H11 is higher than the H8 but the sand body is thinner. By calculating the density of the fracture, we can also make better prediction of more sweet areas.