Reservoir Characteristics (Porosity and Water Saturation) for Selected Wells of Yamama Formation in ER Oilfield, Southern Iraq

The petrophysical study was conducted for hydrocarbon assessment using well log data from two wells in the ER Oilfield for Yamama Formation, Early Cretaceous, in the southern Mesopotamian Basin, Iraq. The boundaries of the Yamama Formation in ER-1 are 2868.9 m at the top and 3168 m at the bottom, and ER-9 is 2838.78 m and 3146 m at the bottom. The thickness of the wells ER-1 and ER-9, respectively, is 299.06 and 307.76 m. The reservoir parameters of the Yamama Formation were determined using accessible well logs from wells ER-1 and ER-9, which included resistivity, neutron, gamma ray, and density data. Lithological studies were conducted with porosity log cross plots, such as Neutron porosity cross plots. These cross plots revealed that the Yamama Formation is mainly composed of limestone, with calcite and minor quantities of dolomite as principal mineral components. Petrophysical characteristics such as porosity, water saturation, and hydrocarbon saturation were determined by employing Techloge software to conduct the creation of the complete computer-processed analysis of reservoir features. According to the petrophysical characteristics of the examined wells, Yamama Formation is divided into four units. These units are: Yamama A, Yamama B1, Yamama B2 and Yamama C. In general, Yamama Formation in ER oil field for units Yamama A, and Yamama B1 it is consideredas water reservoir according to the somewhat high porosity (7 and 10) % for Yamama A and (11 and 13) % for Yamama B1. and high-water saturation of (52, and 90) % for Yamama A, and (78 and 87) % for Yamama B1. As for Unit Yamama B2, it is considered an oilreservoir where a high percentage of hydrocarbons is present in the middle and lower part of ER1 and in the upper part of ER9 and it contains oil evidence in various parts of the unit, with water saturation of (42% and 46) %, and porosity of (13-15), and as for Yamama C, it is considered the mostimportant oil reservoir in Yamama formation due to its high percentage of hydrocarbons (61 and 71) % and low water saturation of (29 and 39) % with porosity (8-14) %.