Assessing Diagenetic Variability and Its Role in Reservoir Heterogeneity: Implications for Enhanced Oil Recovery in the Tuba Formation, Kuwait

This study evaluates the impact of diagenetic variability on reservoir heterogeneity in the Tuba Formation (Upper Cretaceous), Kuwait. It aims to characterize how cementation, dolomitization, dissolution, and compaction influence porosity, permeability, and fluid flow properties. The study also investigates how these variations affect Enhanced Oil Recovery (EOR) strategies. The research integrates core analysis, thin-section petrography, scanning electron microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Mercury Injection Capillary Pressure (MICP) testing, and well log analysis to examine the diagenetic features and their effect on reservoir quality. A conceptual 3D model was developed to visualize the distribution of facies and diagenetic zones. The study revealed that diagenetic variability significantly impacts the heterogeneity of the Tuba Formation. High-permeability zones (e.g., dolomitized grainstones and dissolution-enhanced facies) exhibit intercrystalline and vuggy porosity, while low-permeability zones (e.g., cemented mudstones and compacted wackestone) show pore occlusion and low permeability. MICP results confirm that dolomitized and dissolution-enhanced zones have higher permeability (up to 500 mD), while cemented zones exhibit low permeability (<0.1 mD). 3D modeling visualized how facies and diagenetic features control fluid flow in the formation. The study's findings suggest that EOR strategies must account for diagenetic heterogeneity, with targeted interventions (e.g., fracturing or acidizing) in cemented zones, while optimizing water flooding or CO₂ injection in more permeable streaks. This study used a different approach to integrating diagenetic analysis with 3D modeling to assess reservoir heterogeneity, offering insights into optimizing EOR techniques in tight carbonate reservoirs.