2D Forward Numerical Simulation Of IP Method In Time Domain

IP method, which is based on the differences of the induced polarization characters of minerals or rocks, deals with the geological exploration issues by measuring the decay curve or the apparent resistivity frequency spectrum of the ground and evaluating parameters of abnormalities. There are several unique advantages by using this method, especially when the conductivity of the abnormalities is very close to surrounding rocks. Therefore, In order to employ the IP parameters more efficiently in the inverse problem and abnormality evaluation, it's of great importance to study the forward numerical simulation of this method.In the electric exploration, the conductivity and IP effect of the ground can be seen as similar to the linear time-invariant, and rock dispersion of polarization effects can be formulated by Cole-Cole model. In this article, from the frequency domain model of expression, its time-domain expression could be derived through the Laplace transform. According to the digital filtering algorithms of D. Guptasarma, the calculation ofΓfunction in this expression can be resolve through the linear digital filter. In addition, according to the theory of equivalent resistivity, converting various geological resistivity into the equivalent resistivity of corresponding inducing time, any potential numerical simulation methods without considering IP effect could be used to simulate polarization domain total field value, thus the polarization and other parameters can be calculated.Finite element method which is now widely used in forward numerical simulation of electrical method, has formed a mature theory and problem-solving process. This paper from the basic point, the issue of two-dimensional point source forward, discussed the use of finite element theory to solve the problem. According to Time Domain IP two-dimensional forward calculation requirements, analyzing the theory of the finite element, prepared a two-dimensional process forward. Then, by comparing analytical value or the value of physical simulation to the value produced by the forward program, evaluation and verification of the accuracy and reliability of the program were gained. Finally, discussed the relationship between changes of the frequency correlation coefficient C and time constantτof the Cole-Cole model and the variation of apparent polarizabilty parameters.