Determination of Appropriate Sequence Stratigraphic Model for Reservoir Zonation in Upper Dalan Member, Central Persian Gulf

Kangan and Dalan formations are the main reservoir rocks of the central Persian Gulf hydrocarbon fields. The aim of this study is determining the approprate sequence stratigraphic model to separate the reservoir zones of the carbonate-evaporate Dalan Formation. In this regard, a total of 9 facies and 4 depositional environments determined using petrographical studies. The sequence stratigraphic boundaries determined in two transgressive-regressive and EXXON models using all available data. One complete third order sequence as well as two other incomplete sequences determined in the first method that continue in Nar anhydrite and Kangan Formation respectivly. In the second method, the studied interval was divided into two sequences and 6 systems tracts. Regarding the chosen methods, the LST of each EXXON sequence is part of the HST of the previous sequence. In LST, precipitation of evaporites cause low reservoir properties. TSTs are the same in both models and have good reservoir properties due to the low anhydrite and frequent marine cements. HST is also a good reservoir zone in EXXON model. This systems tract has dual reservoir properties in T-R model because the LST of the EXXON model is also included. The results show that the EXXON model with separating the LST and HST with different reservoir properties has higher ability for differentiation of the reservoir zones in Dalan Formation. These systems tracts have different reservoir quality parameters (porosity and permeability) that is ignored in transgressive-regressive model.