Using Geophysical Well Logs in Studying Reservoir Properties of Mishrif Formation in Garraf Oil Field, Southern Iraq

The characterizations of reservoir require reliable knowledge of certain fundamental reservoir properties. Log measurements can define or at least infer these properties: lithology, resistivity, porosity, permeability, shale volume and water, oil, gas saturation. The current study represents an evaluation of petrophysical properties in well GA-4 for Mishrif Formation in Garraf oil field, southern Iraq. The petrophysical evaluation is based on well logs data to delineate the reservoir characteristics. The available Geophysical well logs images such as (sonic, density, neutron, gamma ray, spontaneous potential, and resistivity logs) were digitized using the Didger software. The environmental corrections and petrophysical parameters such as porosity, water saturation, hydrocarbon saturation, etc. were computed and interpreted using Interactive Petrophysics (IP) program. Lithological, mineralogical and matrix identification were estimated using porosity combination cross plots. Petrophysical properties were determined and plotted as computer processing interpretation (CPI) using Interactive Petrophysics (IP) program. Mishrif Formation in Garraf oil field is divided into three units according to the petrophysical properties: Upper, Middle, and Lower. Middle Mishrif is characterized by good porosity and high hydrocarbon saturation, which represent the main reservoir. Interpretation of well logs approved that Mishrif Formation production in well GA-4 is commercial .Middle Mishrif is characterized by free oil shows .Lithological study of Mishrif Formation shows that it consists mainly of limestone whereas mineralogy consists mainly of calcite with some dolomite.