Dual Impact of Sequence Stratigraphy on Reservoir Quality in Carbonate Reservoirs: An Example from Kangan and Dalan formations in South Pars Gas Field

The main application of sequence stratigraphy is recognition of reservoir and non-reservoir intervals in hydrocarbon- bearing formations. So, it is very important to construct a suitable sequence stratigraphic-based model reservoir zonation schem. The transgressive-regressive model is comprehensively used for this purpose. Sequence stratigraphy of Kangan and upper Dalan formations in South Pars Gas Field has been done based on the EXXON model in this study. Four 3rd order sequences were determined; each sequence contains LST, TST and HST. In Kangan sequences (KS1 and KS2) and lower sequence of upper Dalan Formation (UDS2), the reservoir quality changes similarly. The LST has low reservoir quality due to the high anhydrite content while TST has good reservoir properties. The HST is not a good reservoir again with considerable anhydrite content. In the upper sequence of upper Dalan Formation, there is a reverse order. Regarding the considerable relative sea-level fall at the end Permian time, the anhydrite content is high in TST, while UDS1-HST has good reservoir quality due to dissolution influenced by meteoric water. Results of this study show that the applied model has a considerable ability for carbonate reservoirs zonation.