GENERATION AND MIGRATION OF PETROLEUM IN IRAQ:
by Pitman, Janet K.1, Steinshouer,
Douglas W.2, and Lewan, Michael D.1
Open-File Report 03-192
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* Use of brand names does not constitute endorsement by the U.S. Geological SurveyPreface The Powerpoint presentation in this report was given at the American Association of Petroleum Geologists International meeting in Cairo, Egypt, November, 2002. Some diagrams that appeared in the original presentation have been updated in this report. It presents results of a basin modeling study of the Jurassic Petroleum System in Iraq. Basin modeling provides a strategy for optimizing exploration in frontier areas and evaluating new plays within well-explored basins. A 1D, 21/2D, and 3D modeling study of the Jurassic petroleum system in Iraq was undertaken as part of the USGS World Energy Petroleum Resource Assessment Project in order to evaluate source-rock maturity, controls on reservoir filling, and the petroleum generation and migration history. Model simulations were generated using Integrated Exploration System's (IES) multiphase-flow (Petromod) software, a program designed to simulate multiphase fluid-flow in one, two, and three dimensions. Multi-1D simulations were performed to assess the thermal evolution of the region and, in turn, maturation of the source rocks. Potential hyrocarbon migration pathways and timing of reservoir filling were evaluated based on 21/2 D (ray-tracing) simulations. 3D modeling was undertaken to visualize the distribution of reservoir accumulations and directions of hydrocarbon flow since fluid migration and reservoir filling are three-dimensional processes. Jurassic marine shales and carbonates are the major sources of hydrocarbons produced in the Zagros basin and fold belt. A few studies have been published on the stratigraphy and sedimentology of these source rocks, but information on their burial and temperature histories and regional thermal maturation patterns are generally lacking. The timing and extent of oil generation and secondary migration also have not been adequately addressed. The present study (1) examines source rock maturities using Type II-S kerogen kinetics to describe the kerogen-to-oil transformation process, (2) evaluates the timing of reservoir filling in oil fields, and (3) simulates hydrocarbon migration pathways based on the structural evolution of the basin. A better understanding of the timing and extent of oil generation, formation of traps and seals, and potential migration pathways permits simple risk assessments of areas that have potential (undiscovered) hydrocarbon resources. |
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1 U.S. Geological Survey,
Denver, CO 80225
2 GeoLukas, Denver,
CO 80203
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