Unlocking the hidden pathways: river channel delineation and reservoir characterization in Shurijeh Formation, Kopeh Dagh Basin

The Shurijeh Formation is the primary gas reservoir within the Kopeh Dagh-Amu Darya Basin, deposited in a fluvial and deltaic environment. Due to significant lateral variability associated with floodplain and river channel settings, detailed characterization of river channels is essential for optimal reservoir management. This study employs petrophysical data from 44 wells, complemented by seismic cube, thin section study, and production records, to investigate zone D of the Shurijeh Formation comprehensively. In this paper, we aim to innovatively apply the concept of coefficient of variation (CV) in fluvial type reservoirs. Final results show that zone D ranges from 40 to 50 m thick. The assessment indicates that the interior of the river channel forms a high-quality reservoir zone, with declining reservoir properties beyond its boundaries. Petrography analysis confirm the presence of different conditions inside and outside the fluvial channels. This research highlights the critical role of accurately identifying river channels to optimize well placement and improve hydrocarbon recovery in this basin. Additionally, using the CV parameter, a clear distinction can be understood between river channel sediments and floodplain deposits, which can play a significant role in determining the location of future wells and help prevent dry-hole drilling.