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Hydrocarbon column: calculation of maximum height (view source)
Revision as of 15:31, 31 January 2014
, 15:31, 31 January 2014Initial import
{{publication
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Predicting the occurrence of oil and gas traps
| chapter = Evaluating top and fault seal
| frompg = 10-1
| topg = 10-94
| author = Grant M. Skerlec
| link = http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
==Calculation==
The maximum column of hydrocarbons that can accumulate under a seal occurs when P<sub>b</sub> equals P<sub>d</sub>. If P<sub>b</sub> exceeds P<sub>d</sub>, the hydrocarbons will leak through the seal. If P<sub>b</sub> is less than P<sub>d</sub>, it would be possible to seal a greater column of hydrocarbons.
Therefore, for the maximum hydrocarbon column
:<math>\mbox{P}_{\rm b} = \mbox{P}_{\rm d}</math>
:<math>(\rho_{\rm w} - \rho_{\rm h}) \mbox{gh} &= \frac{2\gamma \cos \theta}{\mbox{R}}\\\mbox{h} &= \frac{\left(\displaystyle\frac{2\gamma \cos \theta}{\mbox{R}}\right)}{(\rho_{\rm w} - \rho_{\rm h})}\mbox{g}</math>
or, in mixed units,
:<math>\mbox{h} = \left(\frac{\mbox{P}_{\rm d}}{\rho_{\rm w} - \rho_{\rm h}}\right) 0.433</math>
where:
* h = height of the hydrocarbon [[length::( ft]])
==Effect on seal capacity==
The height of the hydrocarbon column (h) in the above equations is a theoretical maximum. The actual height is less because of the effect of the reservoir. If the reservoir itself had zero displacement pressure, the height of the hydrocarbon column would attain the theoretical maximum and the OWC would coincide with the free water level. If the reservoir has some displacement pressure greater than zero, then the height of the hydrocarbon column is less than the theoretical maximum, or
:<math>\mbox{h} = \left(\frac{\mbox{P}_{\rm ds} - \mbox{P}_{\rm dr}}{\rho_{\rm w} - \rho_{\rm h}}\right) 0.433</math>
where:
* P<sub>ds</sub> = displacement pressure of the seal
* P<sub>dr</sub> = displacement pressure of the reservoir
==See also==
* [[How capillary properties control seal]]
* [[Buoyant pressure]]
* [[Top seal displacement pressure]]
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Predicting the occurrence of oil and gas traps]]
[[Category:Evaluating top and fault seal]]
| image = exploring-for-oil-and-gas-traps.png
| width = 120px
| series = Treatise in Petroleum Geology
| title = Exploring for Oil and Gas Traps
| part = Predicting the occurrence of oil and gas traps
| chapter = Evaluating top and fault seal
| frompg = 10-1
| topg = 10-94
| author = Grant M. Skerlec
| link = http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm
| pdf =
| store = http://store.aapg.org/detail.aspx?id=545
| isbn = 0-89181-602-X
}}
==Calculation==
The maximum column of hydrocarbons that can accumulate under a seal occurs when P<sub>b</sub> equals P<sub>d</sub>. If P<sub>b</sub> exceeds P<sub>d</sub>, the hydrocarbons will leak through the seal. If P<sub>b</sub> is less than P<sub>d</sub>, it would be possible to seal a greater column of hydrocarbons.
Therefore, for the maximum hydrocarbon column
:<math>\mbox{P}_{\rm b} = \mbox{P}_{\rm d}</math>
:<math>(\rho_{\rm w} - \rho_{\rm h}) \mbox{gh} &= \frac{2\gamma \cos \theta}{\mbox{R}}\\\mbox{h} &= \frac{\left(\displaystyle\frac{2\gamma \cos \theta}{\mbox{R}}\right)}{(\rho_{\rm w} - \rho_{\rm h})}\mbox{g}</math>
or, in mixed units,
:<math>\mbox{h} = \left(\frac{\mbox{P}_{\rm d}}{\rho_{\rm w} - \rho_{\rm h}}\right) 0.433</math>
where:
* h = height of the hydrocarbon [[length::( ft]])
==Effect on seal capacity==
The height of the hydrocarbon column (h) in the above equations is a theoretical maximum. The actual height is less because of the effect of the reservoir. If the reservoir itself had zero displacement pressure, the height of the hydrocarbon column would attain the theoretical maximum and the OWC would coincide with the free water level. If the reservoir has some displacement pressure greater than zero, then the height of the hydrocarbon column is less than the theoretical maximum, or
:<math>\mbox{h} = \left(\frac{\mbox{P}_{\rm ds} - \mbox{P}_{\rm dr}}{\rho_{\rm w} - \rho_{\rm h}}\right) 0.433</math>
where:
* P<sub>ds</sub> = displacement pressure of the seal
* P<sub>dr</sub> = displacement pressure of the reservoir
==See also==
* [[How capillary properties control seal]]
* [[Buoyant pressure]]
* [[Top seal displacement pressure]]
==External links==
{{search}}
* [http://archives.datapages.com/data/specpubs/beaumont/ch10/ch10.htm Original content in Datapages]
* [http://store.aapg.org/detail.aspx?id=545 Find the book in the AAPG Store]
[[Category:Predicting the occurrence of oil and gas traps]]
[[Category:Evaluating top and fault seal]]