Investigation of Sedimentology and Reservoir Characterization of the Aptian-Albian Sediments in a Field of Central Persian Gulf

Abstract

The Aptian - Albian age deposits are one of the most important reservoirs in Persian Gulf of Iran. These are equivalent to Shuaiba Formation in the southern part of the Persian Gulf. Microfacies, depositional environment and diagenetic processes of the studied reservoir formation have been investigated in studied field. Seven microfacies were identified in the studied interval including depositional environment ranged from lagoon to shoal and also open marine. Vertical and lateral facies changes were recognized and compared with modern and ancient depositional environments, showing that the sediments in this area were deposited in a homoclinal carbonate ramp. Variable diagenetic processes have been affected by this formation which has a notable impact on the reservoir quality. It is concluded that cementation, neomorphism and pyritization occluded the pore spaces and pore throat decreasing the reservoir porosity and permeability, while dolomitization, and fracturing increased the porosity and permeability and connection between the open spaces resulting in higher reservoir quality and most of the porosity consists of effective porosity in studied field which ranges between 9 to 18 percent and shows no major changes in the entire field. Considering the low volume of shale and good porosity most intervals of the studied reservoir formation show good reservoir quality in this field.