Scale-Dependent Reservoir Heterogeneity and Development-Geological Implications for the Mishrif MB1 Carbonate Reservoir, A Oilfield, Iraq

Development decisions in thick carbonate reservoirs typically rely on average properties or isolated high-permeability zones, even though these parameters may reflect distinct flow controls. In this study, we propose a scale-dependent diagnostic framework for the Mishrif MB1 reservoir utilizing a comprehensive dataset comprising 145 m of core, 286 cast thin sections, 741 porosity measurements, 699 valid permeability measurements, mercury-injection data, well logs, interwell correlations, and property models. Our analysis reveals that permeability exhibits significantly greater heterogeneity than porosity, demonstrating a coefficient of variation of 2.105 compared to 0.413. More importantly, sublayer rankings diverge considerably across different scales. MB1-2A exhibits the poorest background quality alongside the most pronounced permeability dispersion and the strongest architectural segmentation (0.38 sets m−1). In contrast, MB1-2B and MB1-2C contain broader mixed pore-throat systems; notably, MB1-2C boasts the highest average quality but the lowest segmentation frequency (0.18 sets m−1). Depositional microfacies govern the initial grain-mud fabric and body geometry, while differential dissolution and cementation amplify flow-capacity contrasts, with bioturbation contributing to local variability. Ultimately, these scale-specific heterogeneity profiles provide a robust static geological framework for development decisions, including reservoir subdivision, areal zoning, pathway control, and zonal water allocation. Future integration with dynamic injection-production and connectivity data will serve to validate and refine these evidence-based hypotheses.