Abstract: The heterogeneity of reservoir is one of the most important factors to control the accumulation, production and distribution of oil and gas. Therefore, it is important for the heterogeneity of reservoir to be studied. Heterogeneity of reservoir is treated as regional variation, and it is not only in structural nature, but also in stochastic nature. Based on the work of Jiao Xiguo et.al,the theory of geological statistics, linear programming and through variation function, the experimental variation function curve is matched byk-th spherical model. The aggregate index that appears the variation magnitude and variation speed
and the variation nature is proposed to describe quantitatively the variation nature and complexity of heterogeneity. With practical examples, the advantage and practical application of this method can be seen.

Key words: reservoir characteristics, linear programming, comprehensive evaluation, quantitative description, semi-variation function, k-th spherical model