LAUSR

Abstract The Late Jurassic-Early Cretaceous Chia Gara Formation is an important oil-source rock in Iraqi Kurdistan region. Chia Gara source rock is characterised by high organic matter and sulphur content with Type II_S kerogen. 1D basin models were integrated with geological information and geochemical data from Chia Gara Fm at four well locations in Kurdistan region, northern Iraq. The models of the burial/thermal history indicate that Chia Gara Fm is presently in the peak-oil generation window and some oil cracked to gas during Late Eocene to Late Miocene time. Onset of oil-generation began during the Middle Paleocene- Early Oligocene (60–30 Ma). Oil was generated during the Late Eocene to Late Miocene (48–9 Ma). The models also suggest that the oil was expelled from Chia Gara source rock during the Late Eocene to Late Miocene (37–9 Ma), with a transformation ratio more than 50%. The high transformation ratio of more than 80% in two wells suggests that the generated oil was cracked to gas during the end of Middle Miocene time and continued to present day. The basin modeling results further suggest that Chia Gara Formation acts as a prolific petroleum-source rock and significant of oil and limited of gas have been generated and expelled to any nearby prospect reservoir rocks in the Kurdistan region.