Abstract: In order to reveal the characteristics of the Cretaceous Sarvak Formation carbonate reservoir in the southwestern Zagros Basin, a comprehensive study was carried out by integrating the core, thin section, production test and well log data.Analyses of the reservoir rock types, reservoir space, physical property, electrical property and the factors influencing pore development show that the lithology types of the Sarvak reservoir includes chalky limestone, dolomitic limestone and grainstone.And the reservoir spaces are dominated by secondary dissolved pores and mold pores.The physical property of grainstone is the best.The chalk in chalky limestone is mainly planktonic foraminifera which have well-developed porosity.Generally, the oil-bearing property enhances with the improvement of physical property.The diagenesis also have great impact on reservoir's physical property, and the constructive diagenesis include dissolution, dolomitization, biological disturbance, stylolites of pressolution origin.The physical property of packstone and wackestone are greatly improved under the influences of these constructive diageneses.Microscopically, the development of reservoir's pore is mainly controlled by facies and diagenesis.Laterally, it is also related to tectonic location and sedimentary environment.The physical pro-perty of platform shoal microfacies on structural high is commonly better.The vertical logging response and the areal distribution of physical property of sublayers can be used to identify zones with better physical property and oil-bearing abundance, thus providing a basis for highly productive reservoirs.

Key words: low resistivity, shoal facies, chalky limestone, Sarvak Formation, Zagros Basin