Abstract:

The mixing deposit of N³₂ in Xiaoliangshan region is simply classed as argillaceous mixing deposit, arenaceous mixing deposit and carbonate mixing deposit for reservoir evaluation. On this basis，combining the data of core analysis，the casting thin sections, porosity and permeability analysis, mercury injection test and log, this paper investigates the mixing deposit reservoir of Shizigou Formation in Xiaoliangshan, northwest of Qaidam Basin: The mixing deposit has complex rock structure and various rock type. The pore space of reservoir mainly includes the primary intergranular pores and micropores. The reservoir properties are mainly mediumhigh porosity and low permeability, high displacement and saturation median point pressure, small pore throat radius. The pore structure are generally poor. The sedimentation and diagenesis have played important roles in evolution of resevoir. The sand flat microfacies is the main favorable reservoir facies. Compaction is the major factor that has influence on the reservoir physical property.N³₂are divided into three types according to parameters like physical property, capillary pressure and so on, reservoirs of the typeⅠand type Ⅱ can be taken as the major target zones for increasing reserves.

Key words: Qaidam Basin, Shizigou Formation, mixing deposit, resevoir evaluation