Reservoir Characteristics of the Middle Ordovician Limestone in the Structural Belt of Fault No 1, Central Tarim Basin

The structural belt of fault No 1 in the central Tarim basin is an important zone for hydrocarbon accumulation ,a reservoir dominated by the middle Ordovician limestone During the middle Ordovician, this belt is situated on the margin of carbonate platform where grain bank, reef and mud mound were well developed Affected by the sedimentary facies, the reservoir from the middle Ordovician limestone in this structural belt is much better than that in the peripheral regions The observation of cores and thin sections demonstrates that the reservoir spaces are dominated by pores, fissures and caverns combined at various locations, and that the reservoir is characterized by a lower matrix porosity and a broad distributed permeability Their development is limited substantially by the type of sedimentary facies, diastrophism and diagenesis However, reservoirs in various positions are different each other under the influence of these characteristics