Abstract:

Tahe oilfield, discovered in the Tarim Basin of Xinjiang has 0.1 billion tons of OOIP. Fracture system is a main reservoir type in the Tahe oilfield. The original model of the fracture system was built by the fine carbonate reservoir description. The fractures were divided into structural fracture and diagenetic fracture. The microfractures were developed well and most of them were oil-bearing. There were two strike directions of fracture: one was NEE—SWW，another was nearly S—N. According to the relationship between the fractures and their distributions, the characteristics of rock chemistry and geochemistry of the fractures，the development of the fractures of carbonate reservoir in Ordovician were divided into four periods: the Caledonian period, the early Hercynian period,the late Hercynian-Indosinian period and Yashan-Himalayan period, The controlling factors of formation and development of the fractures were summarized,such as lithology,the thicknesses of the strata, the fault function,the characteristics of structure stress, the local structure,the changes of strata loading, karst and buried depths etc.

Key words: the Tarim Basin, Tahe oilfield, Ordovician, fracture system