Abstract: O2+3carbonate rock is the major reservoir rock in the cen-tral Tarim basin. As the matrix porosity and permeability of the strata is very low, fractures play an important role in gathering and transporting oil and gas. Since the different types of frac-tures differ in genesis, occurrence, scale and capability in stor-
age and transport of oil and gas, a detailed classification scheme is needed to probe the regularity of occurrence and enrichment of oil and gas in the reservoirs. On the basis of detailed investi-gation, the fractures are firstly divided into different types ac-cording to the genesis, type and chacteristics of the fracture-fill-ing material, and the cross-cutting relationship of fractures.
Then, sub-types are determined according to the occurrence and nature of the fractures. The result shows that fractures in the area under study are complax, with 2 types of diagentic and 5 types (or periods) of structural origen, and the structural frac-tures of each period display different occurrence and characteris-tics.

Key words: carbonate reservoir, fracture, classification, Tazhong I#faulted zone