Oil and gas generation history based on burial history reconstruction and thermal maturity modeling of petroleum systems in northern Iraq

Abstract EN

Burial history, thermal maturity, and timing of hydrocarbon generation were modeledfor five key source-rock horizons at five locations in Northern Iraq.

Constructedburial-history locations from east to west in the region are: Taq Taq-1; Qara Chugh-2; Zab-1; Guwair-2; and Shaikhan-2 wells.

Generally, the thermal maturity status of theburial history sites based on increasing thermal maturity is Shaikhan-2 < Zab-1

In well Qara Chugh-2, oil generation fromType-IIS kerogen in Geli Khana Formation started in the Late Cretaceous.

Gasgeneration occurred at Qara Chugh-2 from Geli Khana Formation in the LateMiocene.

The Kurra Chine Formation entered oil generation window at Guwair-2 andShaikhan-2 at 64 Ma and 46 Ma, respectively.

At Zab-1, the Baluti Formation startedto generate gas at 120 Ma.

The Butmah /Sarki reached peak oil generation at 45 Ma atTaq Taq-1.

The main source rock in the area, Sargelu Formation started to generateoil at 47, 51, 33, 28, and 28 Ma at Taq Taq-1, Guwair-2, Shaikhan-2, Qara Chugh-2, and Zab-1, respectively.

The results of the models demonstrated that peak petroleumgeneration from the Jurassic oil- and gas-prone source rocks in the most profoundparts of the studied area occurred from Late Cretaceous to Middle Oligocene.

At alllocalities, the Sargelu Formation is still within the oil window apart from Taq Taq-1and Qara Chugh-2 where it is in the oil cracking and gas generation phase.