Numerical Modeling of Change in Rocks Electrical Conductivity Due to Impurities Rini Oktaviani (a), Umar Fauzi (a*)
(a) Physics of Earth and Complex Systems, Faculty of Mathematics and Natural Sciences,
Bandung Institute of Technology
Jalan Ganesha 10, Bandung 40132, Indonesia
*umarf[at]itb.ac.id
Abstract
A better estimation of electrical conductivity of rock is crucial in well-log interpretation, and reservoir evaluation. One of the factors that affects the electrical conductivity is the presence of impurity such as organic material. This study examines the effect of various types and fraction of impurities on the electrical conductivity of rock. Some models with spherical grain which radii vary between 3-9 voxel and impurities which size of 0.5-2 voxel have been developed and the finite element method (FEM) with energy approach is then implemented to calculate the effective electrical conductivity. FEM is first validated by comparing its result with analytical solution for 2D and 3D models. The calculated result from the FEM in 2D and 3D models shows in a good agreement with analytical ones with error of 1.7% and less than 5%, respectively. The electrical conductivity is estimated at different fractions of hematite as impurity. The result shows that the effective electrical conductivity with hematite decreases compared to the effective electrical conductivity without hematite. Perhaps the conductivity of water-filled the pore is higher than the electrical conductivity of the impurity. The effective electrical conductivity obtained from samples with various conductivities of hematite shows that there is an anomaly especially when the conductivity and fraction of hematite are less than 0.02 and less than or equal to 0.04, respectively. The same method will then be applied to real rock samples.
Keywords: electrical properties- impurity- finite element method
