The Asmari-Gachsran play is an important play in Zagros Basin.We studied the paleogeography evolution

hydrocarbon source rocks

reservoir rocks

cap rocks and hydrocarbon accumulation process and model of the Asmari-Gachsran play.The Cretaceous Kazhdumi source rocks was more deeply buried due to the Noegene-Quarternary Zagoros folding and mostly reached peak hydrocarbon generation.Meanwhile

open fracture networks that penetrate the Cenozoic Asmari limestone

Pebdeh mudstone and the Cretaceous Sarvark limestone were also formed due to the tectonics

and they constitute vertical pathways for hydrocarbon migration the Kazhdumi source rocks to the above reservoirs.In most areas

the hydrocarbons in the Asmari play were directly charged from the Kazhdumi source rocks instead of the Sarvark play.The Asmari and the Sarvark reservoir share the same oil-water contact due to the connection of fractures

thus the shallow Asmari reservoirs were charged earlier than of the deeper Sarvark reservoir

and have higher filling degree.High quality source rocks

vertical open fractures connecting the source rocks and reservoirs

thick evaporate cap rock

and the good timing between peak hydrocarbon generation and trap-fracture development are the key factors controlling hydrocarbon accumulation in Asmari-Gachsran play.