Application of differential evolution algorithm to model-based well log-data inversion

One of the main objectives of well-log data inversion is to find properties of the earth formation from measurements of physical phenomena. Inverse problems associated with many geophysical measurements are often nonunique and multimodal. Consequently, the gradient-type optimization methods to obtain model parameters become ineffective since the accuracy and the convergence of these methods depend highly on initial position and search direction in the parameter space. Evolutionary-type of methods - genetic algorithm, differential evolution, for example arc well suited for such problems. In this paper we apply differential evolution algorithm to invert for the resistivities of the mud and formation, and the diameter of invasion in a borehole.