Fractured Carbonate Reservoir Permeability Estimation by Microresistivity Imaging Logging

Permeability is a key and important parameter to quantitatively evaluate production capacity in oil and gas reservoirs by well logging interpretation. Fractured carbonate reservoirs have complicated pore structures and fractures, making reservoir evaluations more difficult. Studying effects of different fracture parameters on fluid flow properties in fractured carbonate rock would provide foundations for coming up with novel permeability calculation models in different carbonate layers. There are different fracture parameters controlling fluid flow patterns, including fracture number per unit length, dip, length, aperture, tortuosity, porosity and fractal dimension of fracture center distribution. Conventional experiments are hard to get the representative cores in fractured reservoir. Therefore, digital rock technologies were used to generate fractured carbonate rocks in our research. As a robust numerical simulation method, lattice Boltzmann method was used to calculate rock permeability. Through sensitivity analyses of different fracture parameters on permeabilities, a novel permeability model was developed. In order to guarantee the effectiveness of our method in multiscale rocks, we used upscaling method to acquire equations for calculating a variable parameter in this permeability model. Finally, we applied our permeability estimation method in microresistivity imaging logging interpretation. Results indicate that our method is better than traditional permeability model.