Assessment of reservoir properties and Buckles model for Rumaila Formation in Ahdeb oil field, Central Iraq

Abstract

The present study aims to evaluate the petrophysical properties of the middle Cretaceous Rumaila Formation and to discriminate the heterogeneity of reservoir properties between three wells (AD-1, AD-2 and AD-15) which were drilled at the center of three domes of Ahdeb oil field, Central Iraq. This study was carried out using various types of well log open hole, to determine the petrophysical parameters. These logs are: gamma ray, self-potential, neutron, density, sonic and resistivity. Using Interactive Petrophysics software, the reservoir properties such as porosity, water saturation, hydrocarbon saturation and volume of bulk water have been analyzed and interpreted. This formation’s lithological study was analyzed using cross plots such as the cross-plot neutron/density and cross-plot M–N. The cross plots of studied wells reveal that the Rumaila Formation’s primary lithology is limestone because calcite is the dominant mineral. Based on petrophysical properties, which are calculated using standard equations by Interactive Petrophysics software, Rumaila Formation was divided into four zones: Ru-1, Ru-2, Ru-3 and Ru-4. The zones Ru-1, Ru-3 and Ru-4 are the main oil-bearing units in well AD-1, but they are distinguished by bad reservoir properties on the other wells. Rumaila Formation displays the bulk volume of water and permeability using Buckles model that was accomplished to illustrate the variations in formation permeability and zones of irreducible water saturation.