Abstract: The principal reservoir rocks in the northeastern Tarim Basin are composed of the Sinian-Or dovician dolomites,and the high productive oil reservoirs met by well-known drilling well Shacan-2 are attributed to the Ordovician dolomite system. In this paper, their reservoir properties and the controlling factors are approached. Furthermore, the evaluation of the individual layers of the reservoir and the prediction of favourable regions for the prospecting plays of oil/gas fields have been made in this paper.