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GOR-Isotopes - A New Tool for the Quantitative Assessment of Gas Generation and Gas Typing in Petroleum Systems |
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GOR Isotopes
• What is “GOR Isotopes”?
A user-friendly, PC-based software package for modeling the kinetics of natural gas generation
• How is “GOR Isotopes” different from other gas geochemistry models?
GOR Isotopes is a forward predictive model of gas geochemistry based on kinetics theory (quantum chemistry) and laboratory experiments (pyrolysis) rather than an empirical model based on field observations
• What types of data does “GOR Isotopes” require?
GOR Isotopes requires some knowledge of the type of organic source rock and the thermal history of the basin
• What information can “GOR Isotopes” provide?
Depending on the level of detail of the input data, GOR Isotopes can predict:
Gas Yield Condensate Yield
Gas Source
Gas Composition
Thermal Maturity
Gas Migration History
Gas to Oil Ratio (GOR) Reservoir Filling History
Age of Gas Formation |
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Old Model of Natural Gas Generation
• Natural gas formation (Figure 2A):
Biogenic Gas - derived from bacterial degradation of organic matter
Primary Gas - generated during transformation of kerogen to oil
Secondary Gas - generated by cracking oil to gas
• Natural gas composition (chemical and isotopic) is produced by variable mixing of different end-members
• Natural gas compositions that do not appear to be simple mixtures can be explained by secondary alteration processes (e.g., biodegradation, migration related fractionation, etc.)
• Cross-plots of gas geochemistry show correlations that appear to support this model for specific fields or basins (Figure 2B)
• Empirical correlations derived from field data acquired from one basin can not be applied in other basins |
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Figure 2A: Simplistic Model of Natural Gas Generation
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| Figure 2B: Typical empirical cross-plots of natural gas geochemistry |
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A New Approach for Modeling Gas Geochemistry
• Despite the fact that gas formation is a more complex process than oil formation, the geochemical techniques currently employed for natural gas exploration are still relatively simplistic
• In contrast to oil which is generated in the so-called "thermal oil window", natural gas is generated throughout the entire thermal evolution of sedimentary basins (Figure 2C)
• The combination of kinetics theory with laboratory experimental data allows for the development of a more accurate model of natural gas generation
• This approach enables forward predictions to be made for specific basins based upon the source rock type and the thermal history of the basin
• Integration of kinetic model results into basin models provides a powerful tool for understanding natural gas formation, minimizing exploration risk, and maximizing realized gas resources |
Figure 2C: Conceptual Model of Natural Gas Generation in Petroleum Systems |
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