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Top seal displacement pressure (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==
Displacement pressure (P<sub>d</sub>) is the pressure necessary to force hydrocarbons into the pore space of a rock and form a continuous hydrocarbon filament.<ref name=ch10r67>Schowalter, T., T., 1979, Mechanics of secondary hydrocarbon [[migration]] and entrapment: AAPG Bulletin, vol. 63, no. 5, p. 723–760.</ref> Displacement pressure, which is measured in dynes/cm<sup>2</sup>, can be calculated by the following formula:
:<math>\mbox{P}_{\rm d} = \frac{(2\gamma \cos \theta)}{\mbox{R}}</math>
where:
* γ = interfacial tension, dynes/cm
* θ = contact angle or [[wettability]], degrees
* R = pore throat radius, cm
==Variables==
The displacement pressure of a seal depends on both the physical character of the seal (pore throat radius and pore throat size distribution) and the physical character of the hydrocarbons (interfacial tension and wettability).
==Wettability==
The wettability, or contact angle θ, is 0° for hydrocarbon/water.<ref name=ch10r5>Berg, R., R., 1975, [[Capillary pressure]] in [[stratigraphic trap]]s: AAPG Bulletin, vol. 59, no. 6, p. 939–956.</ref> If the wetting phase is oil or gas rather than water, the contact angle can range from 0 to 180°. Not all rocks are water wet, and oil-wet seals may not be as rare as commonly thought.<ref name=ch10r15>Cuiec, L., 1987, [[Wettability]] and oil reservoirs, in Kleppe, J., Berg, E., W., Buller, A., T., Hjemeland, O., Torsaeter, O., eds., North Sea Oil and Gas Reservoirs: London, Graham and Trotman, p. 193–207.</ref> Organic-rich sediments may be source, seal, and oil wet.
==Interfacial tension==
Hydrocarbon/brine interfacial tension values typically range from 15–72 dynes/cm.<ref name=ch10r87>Vavra, C., L., Kaldi, J., G., Sneider, R., M., 1992, Geological applications of [[capillary pressure]]: a review: AAPG Bulletin, vol. 76, no. 6, p. 840–850.</ref><ref name=ch10r67 /><ref name=ch10r92>Watts, N., L., 1987, Theoretical aspects of cap-rock and fault seals for single and two-phase hydrocarbon columns: Marine and Petroleum Geology, vol. 4, no. 4, p. 274–307., 10., 1016/0264-8172(87)90008-0</ref> Laboratory studies provide interfacial tension values for a range of gas and oil compositions.<ref name=ch10r31>Firoozabadi, A., Ramey, H., J. Jr., 1988, Surface tension of water-hydrocarbon systems at reservoir conditions: Journal of Canadian Petroleum Technology, vol. 27, no. 3, p. 41–48., 10., 2118/88-03-03</ref>
==See also==
* [[How capillary properties control seal]]
* [[Buoyant pressure]]
* [[Calculating maximum hydrocarbon column]]
==References==
{{reflist}}
==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==
Displacement pressure (P<sub>d</sub>) is the pressure necessary to force hydrocarbons into the pore space of a rock and form a continuous hydrocarbon filament.<ref name=ch10r67>Schowalter, T., T., 1979, Mechanics of secondary hydrocarbon [[migration]] and entrapment: AAPG Bulletin, vol. 63, no. 5, p. 723–760.</ref> Displacement pressure, which is measured in dynes/cm<sup>2</sup>, can be calculated by the following formula:
:<math>\mbox{P}_{\rm d} = \frac{(2\gamma \cos \theta)}{\mbox{R}}</math>
where:
* γ = interfacial tension, dynes/cm
* θ = contact angle or [[wettability]], degrees
* R = pore throat radius, cm
==Variables==
The displacement pressure of a seal depends on both the physical character of the seal (pore throat radius and pore throat size distribution) and the physical character of the hydrocarbons (interfacial tension and wettability).
==Wettability==
The wettability, or contact angle θ, is 0° for hydrocarbon/water.<ref name=ch10r5>Berg, R., R., 1975, [[Capillary pressure]] in [[stratigraphic trap]]s: AAPG Bulletin, vol. 59, no. 6, p. 939–956.</ref> If the wetting phase is oil or gas rather than water, the contact angle can range from 0 to 180°. Not all rocks are water wet, and oil-wet seals may not be as rare as commonly thought.<ref name=ch10r15>Cuiec, L., 1987, [[Wettability]] and oil reservoirs, in Kleppe, J., Berg, E., W., Buller, A., T., Hjemeland, O., Torsaeter, O., eds., North Sea Oil and Gas Reservoirs: London, Graham and Trotman, p. 193–207.</ref> Organic-rich sediments may be source, seal, and oil wet.
==Interfacial tension==
Hydrocarbon/brine interfacial tension values typically range from 15–72 dynes/cm.<ref name=ch10r87>Vavra, C., L., Kaldi, J., G., Sneider, R., M., 1992, Geological applications of [[capillary pressure]]: a review: AAPG Bulletin, vol. 76, no. 6, p. 840–850.</ref><ref name=ch10r67 /><ref name=ch10r92>Watts, N., L., 1987, Theoretical aspects of cap-rock and fault seals for single and two-phase hydrocarbon columns: Marine and Petroleum Geology, vol. 4, no. 4, p. 274–307., 10., 1016/0264-8172(87)90008-0</ref> Laboratory studies provide interfacial tension values for a range of gas and oil compositions.<ref name=ch10r31>Firoozabadi, A., Ramey, H., J. Jr., 1988, Surface tension of water-hydrocarbon systems at reservoir conditions: Journal of Canadian Petroleum Technology, vol. 27, no. 3, p. 41–48., 10., 2118/88-03-03</ref>
==See also==
* [[How capillary properties control seal]]
* [[Buoyant pressure]]
* [[Calculating maximum hydrocarbon column]]
==References==
{{reflist}}
==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]]