Abstract: A method based on fuzzy comprehensive judge technique is developed to classify and evaluate sand bodies. The classification criteria are set through
correlation analysis and relative-value comparison, and a staged function is used to determine the grade of membership. By applying the theory of analytic
hierarchy process ( AHP), the weights of factors are fixed. After analyzing the results obtained from dif-ferent fuzzy comprehensive models, a suitable model
is chosen and is used for the classification. The method is used to classify sand bodies of 13 single sand beds in the 1st and 2nd members of the Dongy-
ing Formation in Dalujia area, with a success rate of more than 90%, which verifies the validity of the method.

Key words: Sand body, Classification, Fuzzy tech-nique, Dongying Formation, Dalujia area