Integrated stratigraphic study of the Cretaceous petroleum-potential succession, Sulaimani area, Kurdistan, Iraq

Basim Al-Qayim , Shireen Hussein , Fouad M. Qader , Salim H. Al-Hakari Bestoon Shukor , Ziryan Sardar , Dler Ahmed , and Hawar Abdullah
Department of geology, University of Sulaimani, Kurdistan , Iraq
Geological survey & Mineral Exploration Directorate, Sulaimani, Kurdistan, Iraq


The Cretaceous sequence of Kurdistan Region of northeast Iraq form an important
petroleum system in housing potential source rocks such as the Balambo, Sarmord and
Shiranish Formations. It also includes an important reservoir rocks supplied with good
secondary porosity such as the Qamchuqa and Kometan Formations. This study
examined surface and subsurface sections of these units from Sulaimani area of
Kurdistan region of northeast Iraq using stratigraphic analysis, microfacies
investigations, lithostratigraphic correlation in an attempt to characterize these units at
this area and to give an insight regarding the stratigraphic architectural impact on the
development of their petroleum system. Microfacies analyses show the occurrences of
deep to shallow marine facies. It ranges between basinal foraminiferal- Oligostiginal
grainstone to wakestone (Balambo, Sarmord, Kometan, Shiranish, and parts of the
Tanjero Formations) to bioclastic -foraminiferal packstone to wackestone of the
Qamchuqa Formation. The Dolostone part of the Qamchuqa Formation is characterized
by medium to coarse crystalline planar-e to planar-s type mosaic.
The Late Cretaceous units of the Kometan, Shiranish, and Tanjero Formations in both
outcrop and neighboring subsurface sections, show little stratigraphic differences within
the study area from elsewhere in Kurdistan Region. The Early Cretaceous units of the
Balambo, Sarmord and Qamchuqa Formations (which are the focus of this study),
however, show lateral and vertical stratigraphic variations in lithology and thicknesses in
both northward and westward directions. The basic difference is the change of the deep
marine Oligostiginal marly limestone of the Balambo Formation into the dolomitized
platform carbonates of the Qamchuqa Formation in both directions. This lateral changes
passes through a transitional zone of interfingering relation, which is up to 15Km in
width. This zone plays an important role in developing the Cretaceous petroleum system
of the area.

Key Words:
Cretaceous, Kurdistan,
Stratigraphy, Iraq,
Petroleum System


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