فهرست نشریات علمی دسترسی آزاد ایران

Due to their geological complexity, the Persian Gulf gas fields require more in-depth investigation. The primary reservoir rocks are carbonate sediments, notably the Upper Permian Dalan and Lower Triassic Kangan Formations. The Dalan Formation consists predominantly of oolitic limestone successions, which conformably overlie the Faraghan Sandstone Formation and underlie, unconformably, the carbonate sediments of the Kangan Formation. The Kangan Formation, in turn, underlies the shaly Agar Formation. The boundary between these studied formations corresponds to the Permian–Triassic (P/T) global boundary. In this study, two critical reservoir parameters—porosity and permeability—of the Dalan and Kangan Formations were evaluated using the Nuclear Magnetic Resonance (NMR) method. A thorough understanding of reservoir porosity and permeability is essential for optimal field management and prolonging the productive lifespan of the gas field.Based on petrophysical properties, the studied succession has been subdivided, from top to bottom, into four units, designated K1 through K4. The results revealed significant differences in the reservoir characteristics of each unit. Units K1 and K2 belong to the Kangan Formation, while units K3 and K4 correspond to the Dalan Formation. Unit K2 exhibits the lowest hydrocarbon potential in terms of reservoir quality, whereas unit K4 of the Dalan Formation shows the highest porosity and permeability values. The permeability of the studied sequence was estimated using three approaches derived from NMR data: the Schlumberger-Doll Research (SDR) model, the T2 (so-called) model, and the Free Flow and Swanson models, based on the calculated porosity. Comparison of the results indicated that the SDR model provides the most reliable permeability estimates.For sedimentary modeling, the accurately determined porosity and permeability parameters were integrated with geological interpretations. The analysis of the upper and lower deposits across the P/T boundary indicates that erosional events significantly affected reservoir quality. The findings of this study can aid in predicting reservoir performance and reducing drilling risks within the studied basin.