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Pepper, Andrew1
(1) Amerada Hess Corp, Houston, TX

ABSTRACT: How Complex Do Kinetic Models Need to Be?

Kinetic models of petroleum generation have evolved remarkably from easy-to-compute but fundamentally unsound models such as TTI of the early 1980s. At present, the modeler has access to single component models (bulk transformation) extrapolated from laboratory pyrolysis experiments, two-component models calibrated in the laboratory and field, and multi-component models based again on laboratory extrapolation. 
Many of these models concern themselves with primary generation; using these for prospecting work implies an open system with all products from kerogen breakdown available for migration. Primary migration out of the source bed, when considered, is treated using saturation models and concepts of relative permeability. However, it is now widely recognized that release from the kerogen itself plays a major role in determining the petroleum mass, and its composition, available for migration. 
Unfortunately, models of petroleum release from kerogen have not kept up with the increasing complexity of the generation models. The result: only one available scheme is internally coherent in treating the processes of primary generation and secondary cracking within, and release from, kerogen. This is the two-component scheme ExCaliber, adapted from BP’s ORGAS2 model. 
We demonstrate how quite sophisticated results can be derived by combining this simple, two component model with an “engineering correlation” approach to derive parameters such as volumetric GOR, stock tank liquid gravity (API), reservoir fluid density, viscosity and IFT. 
On the other hand, compositional, custom-kinetic “generation-only” approaches have a long way to go before delivering answers that are useful in practical exploration and development situations.


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