The Evaluation of Reservoir Quality of Sarvak Formation in One of Oil Fields of the Persian Gulf

Abstract

Sarvak formation, with the middle cretaceous (Cenomanian) age, is one of the stratigraphic units of the Bangestan group in the southern Iran. The carbonate rocks of this formation form the reservoir rock in the study field. Generally, Sarvak formation is subdivided into three members including Mishrif, Khatiyah, and Maddud in the Persian Gulf, and the average thickness of the reservoir unit (i.e. Mishrif) in the field varies from 55 to 73 meters. The purpose of this study is to investigate the petrophysical properties of Sarvak formation in terms of rock type and hydraulic flow unit analysis. In this context, at the first step, the geological characteristics (i.e. sedimentary texture and diagenetic features) of the reservoir rocks were studied in this field. Then, the core porosity and permeability data obtained from different facies plots of the petrophysical diagram of Lucia in which different facies distribute on the three petrophysical classes of diagram based on sedimentary and diagenetic characteristics resulted in the differentiation of eight rock types. Also, using the concept of reservoir quality index (RQI) and flow zone index (FZI), eight hydraulic flow units were recognized and named as A, B, C, D, E, F, G, and H in an ascending reservoir quality order. The results show a good relation between different identified rock types and HFUs in the reservoir, which can be interpreted based on geological attributes.