Zagros basin in Middle East: Along-strike variations of structure and petroleum accumulation characteristics

Abstract

The Zagros basin is one of the most important petroleum-bearing foreland basins in the world, with quite different reserves of different sections along strike. To understand structural characteristics, oil and gas accumulation and the controlling factors is an important foundation when developing the oversea new venture evaluation. We take the the synthetical analysis of the along-strike (NW-SE) structural deformation differences, hydrocarbon accumulation and the controlling factors of the Diyarbakir section of Turkey, the Kirkuk section of Iraq, and Luristan, Khuzestan and Fars sections of Iran. The results show an obviously different 2P recoverable reserves of oil and gas along the strike in the Zagros basin. The Khuzestan section has the largest reserves and is dominated by Neogene reservoirs. The Zagros orogenesis forms a series of anticline structures, and the evaporite caprock forming in different periods affects the oil and gas accumulation differences in various sections of the basin. Since the Miocene, with the continuous collision between the Arabian plate and the Eurasian plate and the large-scale compression and folding occurring in the basin, the Lower Cretaceous hydrocarbon can migrates upward to the Oligocene-Miocene reservoirs along the fractures. The Cenozoic sediment is quite thick in Kirkuk and Khuzestan sections, and the Oligocene-Miocene evaporite can be a quite good regional caprock. The deformation in Fars section is strong, and the Upper Jurassic and Miocene evaporites are destroyed in different scale and the hydrocarbon mainly accumulates within the Upper Permian to Lower Triassic carbonate reservoirs. This study will provide the guidance of the new venture evaluation of the Zagros basin.