Integrated Petrophysical Characterization and 3D Static Modeling of the Early Cretaceous Zubair Reservoir: Implications for Hydrocarbon Asset Evaluation in Luhais Oilfield, Southern Iraq
This study presents an in-depth reservoir properties of the Zubair Formation in the Luhais Oil Field in southern Iraq. Geologically speaking, the formation is situated in the Thamama Group, which is part of the Early Cretaceous Eighth Megasequence (AP8). By integrating wireline log data with 3D structural and petrophysical modeling, the study evaluates the reservoir's spatial heterogeneity and storage capacity. Sandstone intervals with adjacent shale successions comprise most of the Zubair Formation, which has been split into three members and four distinct reservoir units. The upper sand member is the primary interval that contains hydrocarbons, according to the analysis results. Based on petrophysical analyses, the sandstone-dominated Units A and C have good reservoir quality, with moderate-to-high permeability levels between 76 and 328 mD and porosity values between 15% and 25%. Also, these units show quite low water saturation (0.22–0.37), suggesting a high potential for hydrocarbon accumulation. On the other hand, due to their high water saturation and low permeability, Units B and D which have a high shale content act as non-reservoir intervals; these intervals are thought to serve as both hydraulic barriers and potential source rock facies. The most productive zones are contained within the upper sand member, as confirmed by the developed 3D geological and petrophysical models that successfully define the geographic distribution of these characteristics.