Biostratigraphy and sequence stratigraphy of the Guadalupian deposits of the Dalan Formation in the eastern of the Qatar-Persian Arc, Persian Gulf

One of the most important carbonate gas reservoirs in the Zagros and Persian Gulf sedimentary basins is the Dalan Formation. This research investigates the microfacies, lithostratigraphy, and sequences of carbonate-evaporite deposits in the Lower member of the Dalan and the Nar member belonging to the Guadalupian series with a total thickness of 2402 meters in four wells namely A, D, E, and G located in the eastern part of the Qatar-Persian arc in the Persian Gulf. The study of 340 thin sections prepared from the drilling cutting pieces with 2-meter intervals of well E, and a review of documents related to other wells led to the identification of 20 species belonging to 14 genera of foraminifera and the foraminiferal assemblages consisting of 65 species belonging to 25 genera. A foraminiferal biozone was recognized in well E, assigned to the Wordian? - Capitanian: Pachyphloia- Globivalvulina- Hemigordius, Assemblage Zone.  Additionally, 11 microfacies were determined, mainly distributed in five environments (sabkha, intertidal, lagoon, shoal, and shallow marine). Based on the stacking patterns facies and the gamma-ray log trends, two 3rd-order transgressive–regressive (T-R) sequences were determined. These sequences correspond to the sequences of the reservoir unit’s equivalent formations in the southern and eastern Tethyan basin including Saudi Arabia, UAE, Oman, Iraq and South China.