The objective of this paper is determining the petrophysical properties of the Mauddud Formation (Albian-Early Turonian) in Ratawi Oil Field depending on the well logs data by using interactive petrophysical software IP (V4.5). We evaluated parameters of available logs that control the reservoir properties of the formation, including shale volume, effective porosity, and water saturation. Mauddud Formation is divided into five units, which are distinguished by various reservoir characteristics. These units are A, B, C, D, and E. Through analyzing results of the computer processed interpretation (CPI) of available wells, we observed that the main reservoir units are B and D, being distinguished by elevated values of effective porosity (10%-32%) and oil saturation (95%-30%) with low shale content (6%-30%). Whereas, units A, C, and E were characterized by low or non-reservoir properties, due to high water saturation and low values of effective porosity caused by increased volume shale.

3D Petrophysical model for Mauddud Formation in Ratawi oilfield had been created. Five wells have been chosen in Basra governorate to construct Structural and petrophysical (effective porosity, water saturation and Net /Gross) models. Structural model showed that Ratawi oilfield composed of one anticline fold, where its axis extends toward North to South. After creating zones for Mauddud Formation, which was divided into 5 zones i.e. A, B, C, D and E zone. Layers were built for each zone according to petrophysical properties. A, B and D units were divided in 1 layers as a barrier, While the unit B was divided into 25 layers and the unit D was divided into 15 layers because it represents reservoir zones. The 3D grid of Mauddud Formation model that was built consists of (841295) cell and each cell have dimensions I =91 * J =215 * K =43. Finally, Petrophysical models (effective porosity, water saturation and Net /Gross) had been constructed for each zone of Mauddud Formation. Based on data analyses and results from modelling, the B then D is a important reservoir unit in terms of its good properties (high effective porosity, low water saturation) and increase in production periods from the thickness of the total reservoir.