Study of Facies Changes, Sedimentary Environment and Diagenetic Processes in Sequence Boundaries of Kangan Formation and its Effect on Reservoir Quality According to Lucia›s Classification, in Salman and Lavan Fields

Kangan Formation with Triassic age, it has the largest gas reserves in the Middle East and the world. This formation is in Salman field (Including 187 meters of thickness in the 2SK-1 well and 189 meters of thickness in the 2SKD-1 well) And in Lavan field (including 186 meters of thickness in LN-3 well), and with the sequence of carbonate, limestone, Dolomite limestone, Dolomite with anhydrite Layer, Marl and shale (on the Kangan Formation). According to microscopic studies in the mentioned wells, 15 faces were identified which belong to four facies belts: Sabkha, Tidal flat, Lagoon and Shoal. Based on the identified microfacies, a homoclinal carbonate ramp can be introduced. The known diagenesis processes in the Kangan Formation, which are effective on the reservoir quality are: mechanical and chemical compaction, anhydrite and calcite cement as a reservoir quality reducer and dissolution, dolomitization and fracturing can be mentioned as increasing reservoir quality. The types of porosity observed are: Intragranular porosity, Moldic, Fenestral, vuggy, Intraparticle, and fracture. The vertical changes of the facies indicate three third-order depositional sequences and five fourth-order depositional sequences in Salman and Lavan fields. Each sequence consists of two system tracts, TST (including intertidal, lagoon, back shoal) and HST (including intertidal and shoal) in reservoir units K1 and K2. Reservoir quality study also according to distribution and separation of samples of Grain supported and Mud supported facies, sedimentary environment and the size of dolomite crystals, compared to the available porosities and permeability, indicates class 1 and 2 of Lucia.