ارائه الگوريتمي جديد براي مدلسازي پيشرو سه بعدي در مگنتوتلوريك

A new algorithm for three dimensional magnetotelluric forward modeling

Abstract: Due to the need for greater depth of investigation in petroleum and geothermal exploration and the complexity of the associated geological models often involved in any interpretation of magnetotelluric data, it would be inevitable to employ a jLJUb - ** ^t-ijlS" - * (J*>ULJ) \TA<{ kt ojLvJ. JU . j* ^iip JJ more robust and effective 3-D forward modeling engine capable of incorporating complex geological models. The newly developed algorithm presented in this paper uses the conventional finite difference technique of numerical methods but in a non- staggered scheme which enables solving the governing electromagnetic fields with the imposed boundary conditions simultaneously. Through dividing the air and earth half space into discrete blocky model the governing magnetotelluric equations are discretized to form a linear matrix equation which in turn is solved for the unknown magnetic and electric fields iteratively. Because of the frequency dependency of governing magnetic and electric fields and the finite size of the discretized model a number ofproblems such as oscillating phenomena in the final forward response in the course of solving such boundary value problems are observed. Also it happens that due to the conventional staggered scheme of forming discretized linear equations, a pseudo singularity appears which makes the iterative solvers to diverge. In order to address and remedy for these problems we have introduced an optimum mesh refining scheme to resolve the response oscillation problem. Also through using non staggered formalism which changes the shape of the final discretized matrix equation, it is shown that the pseudo singularity effect could be removed effectively.