Analysis of Fault Zone and Fractures in Cretaceous Formations of X Oil Field Using Well Logs and Drilling Operations Data

The X Oil Field, located in the Salah al-Din Governorate of northern Iraq. This study investigates the subsurface properties of Cretaceous formations (M, H, K) and Late Jurassic Chia Gara Formations, focusing on fault systems, fracture networks, and lithological changes affecting porosity and permeability. The research integrates well logs, thin rock sections, and drilling data, employing advanced analytical techniques such as petrophysical modeling to delineate subsurface fault zones. Key findings include the identification and classification of fault zones into core, damage, and non-damage zones using Yamada's Model. Core fault zones exhibit high fracture densities (up to 8 fractures/meter), mixed rock facies, and enhanced secondary porosity values averaging 15%, making them critical conduits for hydrocarbon migration. Damage zones show moderate fracturing (2–4 fractures/meter) with reduced porosity impacts, while non-damage zones serve as stable references. These results were validated through caliper log, gamma-ray log, and drilling indicators like mud loss and penetration rates. This study provides quantitative insights into fracture density, porosity, and permeability, offering a robust framework for optimizing reservoir management and hydrocarbon extraction strategies. The findings contribute to a broader understanding of fault systems in Cretaceous reservoirs, aligning with similar studies in analogous geological settings. By emphasizing sustainable resource management, this research enhances the economic feasibility of the X field and offers transferable methodologies for fields with comparable structural complexities.