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Pitman, Janet K.1, Thomas S. Ahlbrandt2, Mahendra Verma1, Douglas Steinshour2 
(1) U.S. Geological Survey, Lakewood, CO 
(2) U.S. Geological Survey, Denver, CO

ABSTRACT: Petroleum System Model of the Mesopotamian Basin and Zagros Fold Belt, Iraq, and its Application to Hydrocarbon Resource Assessment

Iraq is a major petroleum-producing country in the Middle East with current proven reserves of 113 billion barrels of oil and 110 trillion cubic feet (TCF) of gas in three (total) petroleum systems. According to the USGS (2000) World Petroleum Assessment, more than 45 billion barrels of potential oil and 120 TCF of potential gas remain to be discovered. The majority of hydrocarbons in Iraq were sourced from Jurassic rocks and trapped in Cretaceous and Tertiary reservoirs in the Mesopotamian Basin and Zagros fold belt. An important part of the petroleum assessment in Iraq involves developing a petroleum-system model of the Mesozoic-Cenozoic section that hosts these source rocks and reservoirs. Multi-1D and 2.5D (flow-path) simulations using IES Petromod software: 1) defined the level and extent of (Jurassic) source-rock maturity, 2) established the temperature and timing of major hydrocarbon events in relation to the age of major traps, 3) computed hydrocarbon migration pathways and areas of closure where petroleum might potentially concentrate, and 4) identified the petroleum charge potential of known prospects relative to modeled flow paths. Modeled results demonstrate that virtually all oil and gas fields, and charged prospects in the Mesopotamian Basin and Zagros fold belt overlie mature source rocks (vertical migration was dominant) and are situated on, or close to, modeled migration pathways and areas of potential petroleum concentration. These findings were used to constrain the number- and size-distribution of undiscovered fields in the basin and fold belt that have the potential to add hydrocarbon reserves in Iraq over the next 30 years.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.