3‐D electromagnetic anisotropy modeling using finite differences

Electric anisotropy is considered an important property of hydrocarbon reservoirs. Its occurrence has great influence on estimation of formation water saturation and other properties derived from electromagnetic (EM) measurements. Conventional tools using coaxial coils often underestimate formation resistivity and thus overestimate water saturation. Multicomponent EM sensors provide the additional information needed for better resistivity‐based formation evaluation. We have developed a finite‐difference method to simulate multicomponent EM tools in a 3‐D anisotropic formation. The new method can model inhomogeneous media with arbitrary anisotropy. By using the coupled Maxwell’s equations, our method consumes about the same computational time to model an anisotropic formation as it would take to model an otherwise isotropic formation. We have verified the finite‐difference method using layered‐earth models that are typically encountered in hydrocarbon exploration and development. Our results show that the ...

[1]  G. Newman,et al.  Frequency‐domain modelling of airborne electromagnetic responses using staggered finite differences , 1995 .

[2]  J. Klein,et al.  Induction Log Anisotropy Corrections , 1993 .

[3]  G. W. Hohmann,et al.  4. Electromagnetic Theory for Geophysical Applications , 1987 .

[4]  R. N. Edwards,et al.  Offshore electrical exploration of sedimentary basins: The effects of anisotropy in horizontally isotropic, layered media , 1984 .

[5]  G. E. Archie The electrical resistivity log as an aid in determining some reservoir characteristics , 1942 .

[6]  L. Knizhnerman,et al.  Spectral approach to solving three-dimensional Maxwell's diffusion equations in the time and frequency domains , 1994 .

[7]  P. Wannamaker,et al.  Three-dimensional magnetotelluric modeling using difference equations­ Theory and comparisons to integral equation solutions , 1993 .

[8]  T. Tamarchenko,et al.  Fast frequency domain electromagnetic modeling in axially symmetric layered media , 1994 .

[9]  G. W. Hohmann,et al.  A finite-difference, time-domain solution for three-dimensional electromagnetic modeling , 1993 .

[10]  J. H. Moran,et al.  Effects of formation anisotropy on resistivity‐logging measurements , 1979 .

[11]  K. Yee Numerical solution of initial boundary value problems involving maxwell's equations in isotropic media , 1966 .

[12]  Martin G. Luling,et al.  Response Of 2-mhz Lwd Resistivity And Wireline Induction Tools In Dipping Beds And Laminated Formations , 1992 .

[13]  Jacques R. Tabanou,et al.  Which Resistivity Should Be Used To Evaluate Thinly Bedded Reservoirs In High-Angle Wells? , 1999 .

[14]  J. T. Smith Conservative modeling of 3-D electromagnetic fields, Part I: Properties and error analysis , 1996 .

[15]  J. Schneider,et al.  A finite-difference time-domain method applied to anisotropic material , 1993 .