S-wave velocity estimation method in carbonate reservoir

Key words:  geophysical prospecting  petroleum reservoirs  lithology  carbonate reservoir  S-wave velocity  mineral elastic modulus  pore microstructure  genetic algorithm

Abstract:

Based on rock physics theory, the elastic modulus of rock matrix, rock frame and the velocities of saturated carbonate rocks were calculated. Considering pore shape and connectivity, pores of carbonate rocks were divided into four types:vugs, interparticle pores, cracks and shale pores. The aspect ratio and porosity of each pore type were calculated. An inversion method based on adaptive genetic algorithm was proposed. The bulk and shear modulus of mineral components were inversed using measured P-wave velocities as a constraint. Based on this description of mineral compositions and pore microstructure, S-wave velocities were calculated using Patchy saturation model. The S-wave velocity estimation method was applied to actual logging data, and the favorable results were obtained. The method can provide benefit for complex carbonate reservoir prediction.