Integration of facies, diagenetic, and sequence stratigraphic studies in reconstructing the stratigraphic architecture of the Bangestan reservoir in the Hengam Field, eastern Persian Gulf

The Sarvak and Ilam formations constitute the main reservoir rocks of the Hengam Field at the easternmost part of the Persian Gulf. In this field, the Sarvak Formation exhibits variable thickness and comprises the Mauddud, Ahmadi, and Mishrif members. Facie analysis from one of the cored wells indicates that the Late Albian Mauddud Member was deposited in a carbonate platform different from the Mishrif member. The Ilam Formation consists of three facies, which were deposited in a shoal-lagoon complex.
Petrographic studies reveal that the identified facies underwent post-depositional diagenetic processes, including marine, meteoric, and burial diagenesis. The impact and intensity of meteoric diagenesis played a significant role in porosity development and distribution in the upper part of the Mauddud and Mishrif members, and the Ilam Formation.
Sequence stratigraphic analysis led to the identification of four third-order depositional sequences within this reservoir. The first depositional sequence corresponds to the Mauddud Member, while the second and third depositional sequences align with the Ahmadi and Mishrif members. The third depositional sequence is identified only in the central wells of the field, while it is absent in the northern and southern wells. The study results suggest that during the compressional regime of the mid-Cretaceous and the uplift of fault blocks, the entire third depositional sequence and part of the second depositional sequence were removed due to subaerial exposure and erosion following the post-Cenomanian to post-Turonian events in the northern and southern wells, whereas they were preserved in the central wells.