Fractal Approach for Naturally Fractured Reservoirs Characterization Using Reservoir Simulation

Abstract Fractals are present in the naturally fractured reservoirs, that implies a pressure response is affected by a power law behavior in the fracture properties showing characteristics in their pressure drop performance deviating the typical and idealized Warren and Root (1963) approach for reservoir characterization. The work’s objective is to characterize fractal naturally fractured reservoirs for obtaining the fractal parameters and reservoir properties from a pressure drawdown coupling a black-oil reservoir simulator with a power-law based (fractal) distribution of permeability and porosity of natural fractures over the simulation grid plane, thus, analyzing the resulting pressures and production scenarios corresponding to the fractal behavior in naturally fractured reservoirs. The proposed methodology results in an alternative for fractal reservoir characterization applying reservoir simulation modelling. A double-porosity model is constructed to match the pressure behavior with two field cases with fractal behavior identified from pressure drop performance, and noncommon flow regimes resulted because the fractal flow dimension differs from the Euclidian one, which is a fractal special case where the fractal dimension, dmf, is equal to the Euclidean dimension, d=1, 2 or 3. By a pressure history matching, the characterization of the fractal parameters is reached for both field cases as dmf = 1.386 and the connectivity index, θ = 0.17, and dmf = 1.162 & θ = 0.167, respectively. The rest of reservoir unknown parameters were obtained, and a sensitivity analysis of the fractal parameters shows the impact in the pressure responses and the underestimation in the production rate performance compared with the Euclidian 2D flow.