Difference between revisions of "Limitations of quantitative fault seal analysis"
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| part = Predicting the occurrence of oil and gas traps | | part = Predicting the occurrence of oil and gas traps | ||
| chapter = Evaluating top and fault seal | | chapter = Evaluating top and fault seal | ||
| − | | frompg = 10- | + | | frompg = 10-30 |
| − | | topg = 10- | + | | topg = 10-30 |
| author = Grant M. Skerlec | | author = Grant M. Skerlec | ||
| link = http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm | | link = http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm | ||
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==Limitations== | ==Limitations== | ||
| − | The limitations of quantitative fault seal analysis follow: | + | The limitations of quantitative [[Fault trap regime|fault]] seal analysis follow: |
| − | * It applies only to | + | * It applies only to [[Fault trap regime|fault]]ed interbedded [[sandstone]] and [[shale]] sequences. It is not applicable to massive [[carbonate]], [[chert]], or sandstone reservoirs. It has yet to be tested in interbedded shale–carbonate sequences. |
| − | * The seal | + | * The [[seal]] or [[Trap leakage|leak]] threshold [[shale gouge ratio]] (SGR) must be empirically calibrated for each basin, using known [[seal]]ing and [[leak]]ing faults. An SGR threshold for the [[Gulf Coast]] cannot be used for assessing prospects in the [[Gippsland basin]]. The confidence with which a seal can be risked is thus much greater in a production setting or mature basin than it is in a frontier setting. |
| − | * It does not apply to all structural styles, and specifically it does not necessarily apply to faults in foreland fold and thrust belts or strike-slip basins. All basins in which quantitative fault seal analysis has been proven to date are dominated by detached or basement-involved normal | + | * It does not apply to all structural styles, and specifically it does not necessarily apply to faults in [[foreland fold and thrust belts]] or [[strike-slip]] basins. All basins in which quantitative fault seal analysis has been proven to date are dominated by detached or [[basement]]-involved [[normal fault]]s. |
| − | * Cataclasis, diagenetic effects, localized fracturing, sharp changes in the [[permeability]] or displacement pressure of sands, reactivation of earlier normal faults in compression, | + | * [[Cataclasis]], [[Diagenesis|diagenetic effects]], localized fracturing, sharp changes in the [[permeability]] or [[displacement pressure]] of sands, reactivation of earlier normal faults in [[compression]], “[[shale-outs]],” and the lack of [[lateral]] sand continuity in [[fluvial]] sequences can affect seal behavior. |
| − | * The ability to predict fault seal behavior is only as good as the ability to predict the stratigraphy and structure. As with most variables in prospect assessment, uncertainties in structure and stratigraphy lead to a minimum, maximum, and most likely fault seal risk. | + | * The ability to predict [[fault seal behavior]] is only as good as the ability to predict the stratigraphy and structure. As with most variables in prospect assessment, uncertainties in structure and stratigraphy lead to a minimum, maximum, and most likely fault seal risk. |
==See also== | ==See also== | ||
| Line 29: | Line 29: | ||
* [[How fault zones affect seal]] | * [[How fault zones affect seal]] | ||
* [[Quantitative fault seal analysis]] | * [[Quantitative fault seal analysis]] | ||
| − | * [[ | + | * [[Fault seal analysis example: Gulf Coast]] |
==External links== | ==External links== | ||
| Line 38: | Line 38: | ||
[[Category:Predicting the occurrence of oil and gas traps]] | [[Category:Predicting the occurrence of oil and gas traps]] | ||
[[Category:Evaluating top and fault seal]] | [[Category:Evaluating top and fault seal]] | ||
| + | [[Category:Treatise Handbook 3]] | ||
Latest revision as of 17:35, 29 March 2022
| Exploring for Oil and Gas Traps | |
| |
| Series | Treatise in Petroleum Geology |
|---|---|
| Part | Predicting the occurrence of oil and gas traps |
| Chapter | Evaluating top and fault seal |
| Author | Grant M. Skerlec |
| Link | Web page |
| Store | AAPG Store |
Quantitative fault seal analysis is a proven tool in numerous basins. There are, however, limitations.
Limitations
The limitations of quantitative fault seal analysis follow:
- It applies only to faulted interbedded sandstone and shale sequences. It is not applicable to massive carbonate, chert, or sandstone reservoirs. It has yet to be tested in interbedded shale–carbonate sequences.
- The seal or leak threshold shale gouge ratio (SGR) must be empirically calibrated for each basin, using known sealing and leaking faults. An SGR threshold for the Gulf Coast cannot be used for assessing prospects in the Gippsland basin. The confidence with which a seal can be risked is thus much greater in a production setting or mature basin than it is in a frontier setting.
- It does not apply to all structural styles, and specifically it does not necessarily apply to faults in foreland fold and thrust belts or strike-slip basins. All basins in which quantitative fault seal analysis has been proven to date are dominated by detached or basement-involved normal faults.
- Cataclasis, diagenetic effects, localized fracturing, sharp changes in the permeability or displacement pressure of sands, reactivation of earlier normal faults in compression, “shale-outs,” and the lack of lateral sand continuity in fluvial sequences can affect seal behavior.
- The ability to predict fault seal behavior is only as good as the ability to predict the stratigraphy and structure. As with most variables in prospect assessment, uncertainties in structure and stratigraphy lead to a minimum, maximum, and most likely fault seal risk.
See also
- Quantitative fault seal analysis
- How fault zones affect seal
- Quantitative fault seal analysis
- Fault seal analysis example: Gulf Coast
External links
| find literature about Limitations of quantitative fault seal analysis |
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