Characterization of the Yamama Reservoir in the Abu-Amood Oil Field, Nasiriya, Southern Iraq

Abstract

The Abu-Amood (Rafidain) Oilfield considered as one among five main fields of Nasiriya, with multiple oil reservoir units: Mishrif, Mauddud, Zubair, Nahr Umr, Ratawi, and Yamama formations. The current study highlights the findings of identifying and analyzing the petrophysical characterization of the carbonate Yamama reservoir units in the studied oil field in southern Iraq, in order to understand their influence on the reservoir hydrocarbon potential production of the field. A set of wirelines well logs for five wells was investigated for reservoir evaluation and reservoir unit characterization, including gamma-ray, caliper, spontaneous potential, neutron, sonic, density, and resistivity wire logs. The Didger Software utilized for converting the geophysical wireline log images to digital data, which was then transferred to Excel and IP software to determine and interpret the qualitative and quantitative interpretations values, like porosity, permeability, water saturation, hydrocarbon saturation (Sh), and total water volume. According to the gamma-ray vs. neutrons chart, three types of lithology were identified (limestone, argillaceous limestone, and shale). The Yamama Formation is primarily made of limestone, with argillaceous limestone accounting for the majority of the primary mineral components, and the neutron-density relationship chart which also shows a little gas in wells AAm1, 2, 4, and 5. Based on the results of the petrophysical characteristics interpretations of the oilfield wells, the Yamama Formation was include six units: YR-1, YR-2, YR-3, YR-4, YR-5, and YR-6, and separated by five barrier beds. The porosity ratio variety between fair to good (from 0.10 to 0.17%) in reservoir units which are the most significant reservoir units and oil-containing zones due to their good porosity and low water saturation and permeability which variety from very good to moderate in YR-1 unit. The remaining units are considered inefficient reservoir and do not hold hydrocarbons because of low porosity ratio and high-water saturation.