A case study of fracture prediction and its fluid identification for complex carbonate reservoir

For fractured media, the seismic reflection amplitude varies with both offset and azimuth (AVOZ). In this paper, a special inversion algorithm based on P-wave AVOZ is presented for fracture detection, which employs a noise attenuation technique using pre-stack data with limited azimuthal distribution. Furthermore, the fluid identification method in the fracture media based on the AVOZ inversion is also proposed for the description of fractured reservoirs. Then this method is applied to complex carbonate reservoirs in YB1 area, where the seismic data was acquired under limited azimuthal distribution. The inverted fracture density and orientation are reasonable and consistent well with FMI data in the study area. Besides, the fluid identification result is in a remarkable agreement with actual oil-testing results as well. All these outcomes demonstrate the inversion algorithm and fluid identification method presented in this paper are feasible for the comprehensive characterization of fractured carbonate reservoir.