AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Hydrocarbons in the Middle Miocene Jeribe Formation, Dyala, NE Iraq
(1) Palynology and Petroleum Geology College of Science, University of Baghdad, Baghdad, Iraq.
(2) Geomark Research Ltd, Houston, TX.
(3) Departments of Geology, Iraqi Geological Survey, Duhok, Iraq.
The Miocene Jeribe Formation in northern and NE Iraq is composed of dolomitic limestones with porosity of 10-24% and permeability of 30 mD. The formation is an important reservoir unit and is sealed by the anhydrites of the Lower Fars Formation. The Jeribe Formation reservoirs oil and gas at East Baghdad, gas at Mansuriya, Khashm Ahmar, Pulkhana and Chia Surkh, and oil at Injana, Gillabat, Qumar and Jambour.
For this study, oil samples from the Jeribe Formation from the Jambour oilfield were carried out. Graphical plots of the results (including graphs of pristane/nC17 versus phytane/nC18; triangular plots of steranes, tricyclic terpane scatter plots, and graphs of pristane/phytane versus carbon isotope ratio) indicated derivation from kerogen Types II and III. The oils have undergone minor biodegradation and are of high maturity. They are derived from marine organic matter deposited in carbonate-rich suboxic-anoxic settings.
The stratigraphic occurrence of other biomarker ratios and parameters (C28/ C29 sterane ratio of 0.9, an oleanane index of 0.2, and a low value of tricyclic terpane (0.48) indicate a Late Jurassic and Early Cretaceous age, and this age is consistent with palynomorph analysis. Potential source rocks are present mainly in the Upper Jurassic/Lower Cretaceous Chiagara Formation with few in Balambo and Sarmord Formations at the Jambour, Pulkhana, Qumar and Mansuriya fields. Pyrolysate organic matters, palynofacies type (A) and mature on basis of Gleichenidites spore had confirm the hydrocarbon generation and expulsion from the Chia Gara Formation.
Pathways for oil migration from the Chia Gara Formation source to the Jeribe Formation reservoirs were through vertical faults appeared on the seismic section and confirmed by the asphalting catchments in the Upper Cretaceous Shiranish Formation. All these processes and elements are within a total petroleum system of Cretaceous and Tertiary under heist regional seal of the Lower Fars Anhydrite Formation.