Reservoir characteristics evaluation involves the petrophysical parameters study such as porosity, permeability, and saturation; litological variation to depth, and hydrocarbon characteristics such as Net & Gross thickness and hydrocarbon column. ASMARI reservoir of Shadgan oil field is one of the Tertiary carbonate reservoir of Iran, located on 60 km of SE Ahwaz. The reservoir divided into ten zones and includes two separate reservoirs, as upper and lower. Litological variation analtsis indicates that the percentage of shale and limestone increases by increasing depth, and as well as, quartz made up the main component of 2 & 6 zones.Dolomitization as a common process affected on the sandstones zones intensly, and plays the role of cement sandstone. Anhydrite associated with dolomite can support a sabkha model to form dolomite. On the basis of total porosity and permeability data cleared that these parameters unrelated to dolomite processintensity. but related to the dolomite crystal morphology. The euhedral crystals (Rombohedron) act as an effective role to increase permeability.Water/oil saturation of the 4th and 6th zones are at least and maximum value, respectively. Therefore, the 4th zone can be considered as a water bearing zone, which is divided the reservoir into two parts. As it is observed that saturation variation indicates the fractionation of oil and water at whole resevoir. This process resulted from the lithological factor. The 4th zone contains the highest value of hydrocarbon column. This amount is around 5,5 m in 6th and 2,5 m in 2th zones. Thus, these zones prone the higher potential oil production.