Relationship between hydrocarbon micro-seepages and structures by detection of altered minerals using ASTER remote sensing data in the West of Coastal Fars, Zagros, Iran

The Coastal Fars sub-basin located in the Zagros Fold-Thrust Belt contains giant hydrocarbon fields. The existence of hydrocarbon micro-seepage on the surface can be an important indicator for the presence of oil and gas in subsurface formations. So the leakage of hydrocarbon micro-seepage to the surface leads to the alteration of some of the rocks and minerals and causes numerous effects on the surface. Therefore, by detecting these alterations, hydrocarbon seeps in the surface can be recognized. This study aims to investigate the hydrocarbon micro-seepage and its relationship with the structures of the western part of the Coastal Fars sub-basin. For this purpose, the Advanced Spaceborne Thermal Emission and Reflection Radiometer satellite images and remote sensing techniques, such as the band ratio method and the band ratio composite were used as effective tools for detecting alterations due to hydrocarbon micro-seepage. The comparison of the obtained results with surface and subsurface data indicates that there is a close relationship between the amount of hydrocarbons available in the reservoirs and the frequency of micro-seepages at the surface. Also, important structures of the region, such as Dashti strike-slip fault and salt diapirs, have affected the distribution of hydrocarbon micro-seepage and hydrocarbon reservoirs. Among these structures, the Darang buried salt diapir has played a destructive role and caused the evacuation of the reservoir, while Dashti emergent salt diapir has a positive impact on hydrocarbon accumulation.