Simulação de propriedades multifísicas em modelos digitais de rochas sedimentares com análise das variáveis que afetam essas propriedades

Abstract

The physical properties most used in the prospecting and management of hydrocarbon reservoirs are elastic and electrical properties. In order to understand how these properties are affected by pore types and their interconnectivity, this research aims to simulate, using the finite element method, these properties in digital rock models obtained by X-ray microtomography. The simulation results are analyzed using the statistical method of piecewise linear regression. Electrical simulations demonstrated how the porosity of macropores and micropores, as well as their interconnectivities, influence the electrical properties of carbonate and sandy rocks, and consequently, the exponents m and n of the Archie equation. Generally, the cementation exponent (m) is directly proportional to the volumetric fraction of microporous phases and inversely proportional to the connectivity of macropores. The results indicate that there is a direct relationship between the saturation exponent (n) and the interconnectivity of the microporous phase, but an ambiguous relationship with the porosity of macropores, their interconnectivity, and the volumetric fraction of the microporous phase. Simulated elastodynamic properties show an inverse relationship with the volumetric fraction of the microporous phase and the porosity of macropores. The variable with the greatest influence on static moduli is the volumetric fraction of the microporous phase. Finally, numerically simulated elastodynamic moduli exhibit higher values than their corresponding static values, as reported in the literature for conventional experiments. The method developed in this research can be applied to other types of rocks, and analysis of how pore types and their topologies affect the petrophysical properties of carbonate and siliciclastic rocks offers a novel approach for the exploitation of underground natural resources by society, with greater efficiency and lower environmental cost.