Abstract: Based on the production and test results, the electrical and the physical characteristics of the Yizhong Ordovician buried-hill reservoirs,and the characteristics of the fluid一yields from different intervals before and after stimulation are analysed and regularized in this paper. A modification of the existing criterion of classifi-cation of the reservoirs is also suggested. Stimulable reservoirs are classified out from the compacted layers and the argillaceous layers respec-tively. In addition, instead of three types of reservoirs divided with the existing criterion,a five--type reservoir classifi一cation with a new criterion is proposod.

Key words: compacted layers, argillaceous layers, acidification