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| | part = Critical elements of the petroleum system | | | part = Critical elements of the petroleum system |
| | chapter = Evaluating source rocks | | | chapter = Evaluating source rocks |
− | | frompg = 6-1 | + | | frompg = 6-39 |
− | | topg = 6-41 | + | | topg = 6-39 |
| | author = Carol A. Law | | | author = Carol A. Law |
| | link = http://archives.datapages.com/data/specpubs/beaumont/ch06/ch06.htm | | | link = http://archives.datapages.com/data/specpubs/beaumont/ch06/ch06.htm |
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| | isbn = 0-89181-602-X | | | isbn = 0-89181-602-X |
| }} | | }} |
− | Hydrocarbon generation results from computerized 1-D basin [[modeling]] software are typically presented as either open- or closed-system yields. '''Open-system''' models are based on the assumption that hydrocarbons have been expelled from the source rock, have been transported away, and are no longer subject to the thermal conditions of the 1-D model. '''Closed-system''' models assume the hydrocarbons have not been expelled from the source rock and that all generated hydrocarbon phases are subject to further cracking to lighter phases. | + | [[Petroleum generation|Hydrocarbon generation]] results from computerized 1-D basin [[modeling]] software are typically presented as either open- or closed-system yields. '''Open-system''' models are based on the assumption that hydrocarbons have been expelled from the source rock, have been transported away, and are no longer subject to the thermal conditions of the 1-D model. '''Closed-system''' models assume the hydrocarbons have not been expelled from the source rock and that all generated hydrocarbon phases are subject to further [[cracking]] to lighter phases. |
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| ==Implications for yield predictions== | | ==Implications for yield predictions== |
− | Below are examples of yield curves for the same well, based on both open- and closed-system modeling conditions. The open-system model is run with an expulsion efficiency of 70%, meaning 70% of the generated hydrocarbons were expelled before subsequent maturation and were not subjected to secondary cracking to lighter phases. The closed-system model does not incorporate an expulsion component; therefore, the hydrocarbons are subject to cracking to lighter phases. The closed-system model (right) predicts significantly greater quantities of gas at depth than the open-system model (left).
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− | [[file:evaluating-source-rocks_fig6-19.png|thumb|{{figure number|6-19}}. Copyright: results of Genex 1-D basin modeling software, courtesy Institute Français du Petrole.]] | + | [[file:evaluating-source-rocks_fig6-19.png|300px|thumb|{{figure number|1}}Examples of yield curves for the same well, based on both open- and closed-system modeling conditions. Copyright: results of Genex 1-D basin modeling software, courtesy Institute Français du Petrole.]] |
| + | |
| + | [[:file:evaluating-source-rocks_fig6-19.png|Figure 1]] shows examples of yield curves for the same well, based on both open- and closed-system modeling conditions. The open-system model is run with an expulsion efficiency of 70%, meaning 70% of the generated hydrocarbons were expelled before subsequent [[maturation]] and were not subjected to secondary cracking to lighter phases. The closed-system model does not incorporate an expulsion component; therefore, the hydrocarbons are subject to cracking to lighter phases. The closed-system model (right) predicts significantly greater quantities of gas at depth than the open-system model (left). |
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| '''Note:''' In general, open-system models overestimate the quantities of liquids present in a system. Closed-system models overestimate the amount of gas present in the system and are pessimistic in terms of predicting quantities of liquids. Closed-system models typically are not run any more. However, when evaluating older models, consider this effect. | | '''Note:''' In general, open-system models overestimate the quantities of liquids present in a system. Closed-system models overestimate the amount of gas present in the system and are pessimistic in terms of predicting quantities of liquids. Closed-system models typically are not run any more. However, when evaluating older models, consider this effect. |
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| * [[Kerogen type and maturity]] | | * [[Kerogen type and maturity]] |
| * [[Kerogen type and transformation ratio]] | | * [[Kerogen type and transformation ratio]] |
− | * [[Comparison of kerogen types]] | + | * [[Kerogen types: comparison of maturity measures]] |
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| ==External links== | | ==External links== |
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| [[Category:Critical elements of the petroleum system]] | | [[Category:Critical elements of the petroleum system]] |
| [[Category:Evaluating source rocks]] | | [[Category:Evaluating source rocks]] |
| + | [[Category:Treatise Handbook 3]] |