Abstract: Theoreticalmodel of variogram is essential in geostatistics,which is the key parameter in reservoir heterogeneity character ization and stochastic simulation. Aiming at the disadvantages of conventionalusedmethods thatmatch theoretical variogram such as man-made matching method, non- linearmethod of least square, weighted polynomialmatching, an new matching method was presented, which used genetic algorithm to acquire the best fit of theoreticalvariogram. Genetic algorithm is an novelo ptimization method with the characteristic of global optimization.Combined with simulated annealing method, it converged faster than conventional genetic algorithm. Application of the method tomatch theoretical porosity variogram in gas reservoir of Chuan-zhong gas field has shown thismethod was simple and quick for estimating theoretical variogram parameters.

Key words: theoretical variogram, genetic algorithm, estimating parameters, simulated annealing