Analysis of Wide-Azimuth Angle Gathers for Fracture-induced Anisotropy

With the increasing demand for hydrocarbons, and declining oil and gas reserves, fractured reservoirs have attracted much attention from the petroleum industry. The presence of natural and induced fractures in reservoir rock can significantly enhance oil and gas production. On the other hand, it brings new challenges to the oil industry in terms of anisotropic velocity model building and imaging. 3D angle domain common image gathers (ADCIGs) from RTM are now considered as the most powerful tool for velocity analysis. Moreover, the wide azimuth (WAZ) data provide higher S/N and better illumination of subsalts than conventional narrow azimuth data. In this paper, in order to improve the seismic image and to estimate the fracture properties from these anomalies, we study fracture-induced azimuthal anisotropy on WAZ-ADCIG and propose an efficient method for analysing the WAZ-ADCIGs. This method is verified by a physical modelling case study.