Abstract：Deposition of Shizigou formation and upper Youshashan formation in Xiaoliangshan, Qaidam Basin has obvious mixed sedimentary features. According to the characteristic of lithology complex of hybrid rock reservoir, we classify the lithology which was determined by core analysis again for the purpose of logging evaluation. The lithology is divided into shale kind, sand kind and carbonate kind, where carbonate kind can be divided into mic-ritic kind and algal limestone kind. Algal limestone kind is good reservoir, but in small monolayer thickness. Sand kind and micritic kind can be reservoir when the pore structure is good, and they are always in large monolayer thickness. There are obvious differences in logging response characteristics for different kinds of lithology. Combining the plate method with logging data can distinguish and identify reservoir with different lithology effectively.
