Research on the Fractured-Vuggy Reservoir Prediction Technique Based on P-SV Wave Anisotropic Strength Coefficients: A Case Study of the Lunnan Oilfield in the Tarim Basin

The prediction of fractured-vuggy carbonate reservoirs is one of the important research topics for the exploration and development of naturally fractured carbonate reservoirs and also a challenge for seismic reservoir prediction. A fractured-vuggy carbonate reservoir prediction method is developed in this paper, based on the anisotropy strength coefficient of converted shear waves (P-SV waves). From the principles of the P-SV wave AVO analysis, this paper develops the calculation method of the P-SV angle gather, and the P-SV angle gather is generated. The P-SV AVO analysis is performed, and the P-SV wave pseudo-impedance or intercept, and the P-SV wave impedance variation rate or gradient are calculated. The P-SV wave lithology indicator factor (LIF) method is developed, in which the P-SV wave LIF is the product of the P-SV wave pseudo-impedance and its variation rate, representing both lithology and lithological changes. The P-SV wave anisotropy strength coefficient method is constructed to identify fractured-vuggy carbonate reservoirs, and the P-SV wave anisotropy strength coefficient is the LIF correlation coefficient. The time matching method for the P-wave and P-SV target layers is also developed to compute the depth of the target layer bottom interface and realize the time window constraint of the P-SV target layer. The excellent application performance of the developed method in the working area validates the reliability and accuracy of the developed method. The developed method can successfully predict fractured-vuggy reservoir rocks in naturally-fractured carbonate oil and gas reservoirs and provides strong support for the exploration and development of complex naturally-fractured carbonate oil and gas reservoirs.