Keywords : Water Saturation


Determination of the Petrophysical Properties of the Khasib Reservoir, East Baghdad Oil Field, Middle Iraq

Muneef Mohammed; Ashraf Naif Hameed; Hussain Najem Abd

Iraqi National Journal of Earth Science, 2022, Volume 22, Issue 1, Pages 65-75
DOI: 10.33899/earth.2022.133567.1013

This study aims to determine and evaluate the petrophysical characteristics of the Khasib Formation, which represents the main oil-producing reservoir in the East Baghdad oilfield. To accomplish the aim of the study, the log data for five wells have been interpreted using the Schlumberger Techlog 2015.3 software. The main lithology of the Khasib Formation has been determined as limestone based on the interpretation of neutron, density, and sonic logs and using the M-N cross plot method. The shale volume was determined based on the gamma ray log, and the results showed that the shale volume in the Khasib Formation ranges from about 15% to about 27%, and this value increases toward the top of the formation. The total porosity of the Khasib Formation has been determined based on the density and neutron logs, and it is value ranges from about 12% to 23%. The effective porosity was calculated depending on the relationship between the total porosity and shale volume, and the value of this type of porosity ranges from 8% to 18%. The study showed that the B and C units of the Khasib Formation represent the best hydrocarbon-bearing zones, where these units are characterized by high values of effective porosity and oil saturation.

Reservoir Characterization of the Middle Cretaceous Mishrif Formation in the Buzurgan Oilfield, Southern Iraq

Muneef Mohammed; Hameed Salih; Kadhim Mnaty

Iraqi National Journal of Earth Science, 2021, Volume 21, Issue 2, Pages 63-77
DOI: 10.33899/earth.2021.170388

The Mishrif Formation is considered the main oil reservoir in the Buzurgan oilfield, southern Iraq. This study aims to characterize and evaluate the reservoir properties of the Mishrif Formation based on the interpretation of well logs data. The logs data for six wells have been analyzed and interpreted by using Techlog 2015.3 software. The lithology of the Mishrif Formation was determined by using the M-N cross plot method based on the interpretation of density, neutron, and sonic logs. The results showed that the Mishrif Formation is mainly composed of limestone. The shale volume in the Mishrif Formation has been estimated from the gamma-ray log. The results illustrated that the shale volume is about 20% of the bulk volume, and may increase to reach the highest value at the upper part of the MA unit of the formation. The porosity of the Mishrif Formation was calculated based on the interpretation of neutron, density, and sonic logs. To achieve accurate values of porosity, the log-derived porosity has been correlated with the core-derived porosity, and the comparison showed a good correlation between the two types of porosity. The results showed that the Mishrif Formation is characterized by low to medium porosity (about 5% to 18%). The secondary porosity of the formation is most dominant in the MB21 unit compared with the other stratigraphic units of the Mishrif Formations. This indicates that the MB21 unit was affected by the diagenesis processes. The MB21 unit of the Mishrif Formation represents the most dominant reservoir because it was delineated by high effective porosity and high oil saturation.