Application of pre-stack simultaneous inversion in the reservoir prediction in South Yellow Sea basin

Thick marine Mesozoic- Paleozoic carbonate deposits occur in the South Yellow Sea basin. Owing to the high complexity and heterogeneity of the reservoirs which may cause complicated seismic responses, the prediction of carbonate reservoir remains difficult to oil and gas exploration in the basin. Petrophysical data shows that the property indicator factor is sensitive to porosity and thus could be used to judge the quality of carbonate reservoir. Therefore, we optimized CRP the seismic gather, extract the wavelet from different angle and then establish a low frequency model of high precision, and upon the basis we obtained the P-wave impedance(Z_P), S-wave impedance (Z_S), density data(ρ), and finally the property data by rotation of coordinates, which can be adopted to predict the high quality carbonate reservoir. It is revealed that there are carbonate reservoirs in the Upper Sinian dolomite(Z_2d), Middle Cambrian to Ordovician limestone((C - _2-3—O)and the Carboniferous to Permian limestone(C-P_1q). And the quality of reservoir, in particular the weathering crust, leached zone and local dolomite with cavities and fractures in some areas on the paleo-upland, could be improved and become favorable for hydrocarbon accumulation. Facts prove that pre-stack simultaneous inversion can provide reliable geophysical parameters for reservoir assessment and prediction.