Abstract:

 Comprehensive identification of fractures and obtaining the fracture characteristics parameters are mainly based on the observation of the fracture in cores，the interpretation of deep and shallow laterologs and FMI logging and so on from more than 40 wells in Tazhong area of Tarim Basin. The study indicated that structural fractures in Ordovician carbonate reservoir are well developed in Tazhong area, and the high angle fractures and micro-fractures are well developed，and large-middle fractures are poorly developed，and nearly half of fractures are unfilled effective fractures. The densities of fracture lines along fault zone on the plane become big and increase the validity from west to east. There are three vertical fracture zones，including Upper Ordovician fracture zone，the roof within 100 meters of Lower-Middle Ordovician fracture zone， the deeper of Lower-Middle Ordovician fracture zone. The roof within 100 meters of Lower-Middle Ordovician fracture zone is moderately developed zone. The development of fracture is closely related to fault structure and lithology. In the section of fault and the interchange of multiple fractures，the fractures are well developed. The closer distance is from major faults or sub-grade faults, the more fractures develop, and fractures develop more in dolostone than in limestone. The region where fractures develop well is located in the multigroup faults crossing zone in the eastern of Tazhong area.

Key words: Tazhong area, Ordovician, carbonate reservoir, fracture