Abstract: Well Tazhong-82 is located in the middle segment of Tazhong No.1 slope break belt in Tarim basin, which is a one-thousandton well, a major breakthrough in low-energy zone inside the shelf-edged composite of reefs and banks of Upper Ordovician in 2005. But none of commercial oil-gas flow has been found from other 3 wells in west of Well Tachong-82. The analyses of core, thin section, well log data and seismic information indicate that corrosive caverns are developed in east and west sides of Well Tazhong-82, but the development of fracture differs from place to place. There exist very developed multistage structural fractures in east of Well Tazhong-82, which not only change the reservoir quality of reefs and banks, but also allow this reservoir permeability to be better, obtaining higher oilgas production. It suggests that it is fracture or secondary fault that controls the development of the reservoir rocks and hydrocarbon accumulation in this area. This paper can be as a guide for studying the reservoir rock and the well location in this area.

Key words: Tarim basin, Tazhong No.1 fault, slope break belt, reef-bank body, strike-slip fault, karst reservoir