A robust inversion scheme for resistivity/IP sounding data

Abstract

An iterative nonlinear inversion scheme presented here for interpreting resistivity/IP sounding data is found to be efficient and robust. A Tikhonov regularisation technique with iteration adaptive regularisation parameter has been used in the inversion scheme. The scheme uses a half-space composed of layers of equal resistivities and chargeabilities as the starting model. The final inverted model obtained is in good agreement either with the real model for synthetic data or with the borehole information for field data. A comparison of the present scheme with conventional Marquardt and simulated annealing methods on a test model (Inman, 1975) is made, and the present scheme is found to be more robust than the other two schemes. The scheme has been used successfully to invert noise-free and noisy synthetic and field data taken from published literature.