The geological modeling of an oil-bearing reservoir, which specifies the lithology and analyzes the petrophysical parameters of complex reservoir, its being created using Petrel software to construct reservoir models that describe and estimate porosity and water saturation distributions. 3D modeling of carbonate reservoirs has proven to be a highly effective technique for evaluate the economic benefit of the reservoir by estimating the formation petrophysical properties and calculating the oil reserves. The study aims constructed on evaluated Yamama formation in Four drilling wells (Nasiriyah-1, Nasiriyah-3, Nasiriyah-4, and Nasiriyah-5) entering the Yamama Formation of the Al-Nasiriyah field. In Al-Nasiriyah Oil field, and within the Lower Cretaceous Stratigraphic Column in the south of Iraq, the Yamama Formation is one of the most important reservoirs that deposited into shallow marine habitats throughout the (Valanginian- Early Hauterivian) period, that made up of reservoir and impermeable barrier units in the Al-Nasiriyah field, Yamama Reservoir units are divided into three reservoir units (YA, YB, and YC), with the YB reservoir unit subdivided into (YB1, YB2, and YB3) subunits. The main reservoir units are separated by four sharp impermeable barriers represented by (B1, B2, B3, and B4).
