Evaluation of Joint Inversion Algorithm with Logarithmic Treatment for Resistivity Log

The joint inversion of dual laterolog and dual-induction log was evaluated from the linear inversion theory. The generalized inversion method was used for the inverse calculation. A couple of parameters in the inversion algorithm were treated using logarithmic method. The abnormal states resulting from the logarithmic treatment on equations were analyzed. The effects of both the data-resolution matrix and model-resolution matrix on convergence of inversion process were discussed. It indicated that the logarithm treatment can not only weaken the abnormal state obviously, but also can reduce the spread of the data-resolution matrix. The improved inversion algorithm is efficient to enhance the stability and to improve the behaviors of convergence during the inversion process.