Modeling3: Integrating Structural Modeling, Fault Property Analysis, and Petroleum Systems Modeling—An Example from the Brooks Range Foothills of the Alaska North Slope
Carolyn Lampe, Robert A. Ratliff, Kenneth J. Bird, Thomas E. Moore, Brett Freeman, 2012. "Modeling3: Integrating Structural Modeling, Fault Property Analysis, and Petroleum Systems Modeling—An Example from the Brooks Range Foothills of the Alaska North Slope", Basin Modeling: New Horizons in Research and Applications, Kenneth E. Peters, David J. Curry, Marek Kacewicz
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Seismic interpretation and various modeling techniques, including structural modeling, fault-seal analysis, and petroleum systems modeling, have been combined to conduct an integrated study along a tectonically complex compressional cross section in the Brooks Range foothills of the Alaska North Slope. In the first approach, relatively simple models have been developed to show the interaction and codependency of various parameters such as changing geometry over time in a compressional regime, character and timing of faults with respect to sealing or nonsealing quality, thermal and maturity evolution of the study area, as well as petroleum generation, migration, and accumulation over time, with respect to the geometry changes and the fault properties. Modeling results show that a comprehensive understanding of all aspects involved in basin evolution is crucial to understand the petroleum systems, to be able to reproduce what is observed in the field, and to ultimately predict what can be expected from a prospect area. This integrated approach allows a better understanding of the complex petroleum systems of the Brooks Range foothills.
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Temperature-time–based first-order kinetic models are currently used to predict hydrocarbon generation and maturation in basin modeling. Physical chemical theory, however, indicates that water pressure should exert significant control on the extent of these hydrocarbon generation and maturation reactions. We previously heated type II Kimmeridge Clay source rock in the range of 310 to 350°C at a water pressure of 500 bar to show that pressure retarded hydrocarbon generation. This study extended a previous study on hydrocarbon generation from the Kimmeridge Clay that investigated the effects of temperature in the range of 350 to 420°C at water pressures as much as 500 bar and for periods of 6, 12, and 24 hr. Although hydrocarbon generation reactions at temperatures of 420°C are controlled mostly by the high temperature, pressure is found to have a significant effect on the phase and the amounts of hydrocarbons generated.
In addition to hydrocarbon yields, this study also includes the effect of temperature, time, and pressure on maturation. Water pressure of 390 bar or higher retards the vitrinite reflectance by an average of ca. 0.3% Ro compared with the values obtained under low pressure hydrous conditions across the temperature range investigated. Temperature, pressure, and time all control the vitrinite reflectance. Therefore, models to predict hydrocarbon generation and maturation in geological basins must include pressure in the kinetic models used to predict the extent of these reactions.