Changes

  | 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  = 10-1

  | frompg  = 10-68

  | topg    = 10-94

  | topg    = 10-68

  | 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

}}

}}

==Calculation==

==Calculation==

The maximum column of hydrocarbons that can accumulate under a [[seal]] occurs when the [[Buoyant pressure|buoyancy pressure]],''P''_b, equals the [[displacement pressure]], ''P''_d. If ''P''_b exceeds ''P''_d, the hydrocarbons will leak through the seal. If ''P''_b is less than ''P''_d, it would be possible to seal a greater column of hydrocarbons.

The maximum [[Hydrocarbon column|column of hydrocarbons]] that can accumulate under a [[seal]] occurs when the [[buoyancy pressure]], ''P''_b, equals the [[displacement pressure]], ''P''_d. If ''P''_b exceeds ''P''_d, the hydrocarbons will leak through the seal. If ''P''_b is less than ''P''_d, it would be possible to seal a greater column of hydrocarbons.

Therefore, for the maximum hydrocarbon column

Therefore, for the maximum hydrocarbon column

==Effect on seal capacity==

==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 oil=water contact 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

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 [http://www.glossary.oilfield.slb.com/en/Terms.aspx?LookIn=term%20name&filter=oil-water+contact oil-water contact] 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>

:<math>\mbox{h} = \left(\frac{\mbox{P}_{\rm ds} - \mbox{P}_{\rm dr}}{\rho_{\rm w} - \rho_{\rm h}}\right) 0.433</math>

==See also==

==See also==

* [[How capillary properties control seal]]

* [[How capillary properties control seal]]

* [[Buoyant pressure]]

* [[Buoyancy pressure]]

* [[Top seal displacement pressure]]

* [[Top seal displacement pressure]]

[[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]]