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{{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
}}
A cross-sealing fault prevents communication of hydrocarbons between juxtaposed sands (reservoirs). Cross-sealing faults can be identified using the following criteria:
* Hydrocarbon-bearing sands against water-wet sands
* Different hydrocarbon contacts
* Different pressures
==Hydrocarbon against water==
A fault is cross sealing if it juxtaposes hydrocarbon-bearing sands with water-wet sands, as illustrated in the following figure. Both oil and gas are prevented from flowing into the sand in the hanging wall (R<sub>d</sub>) by the cross-sealing fault.
[[file:evaluating-top-and-fault-seal_fig10-6.png|thumb|{{figure number|10-6}}See text for explanation.]]
==Different hydrocarbon contacts==
A fault is also cross sealing if it juxtaposes sands with different hydrocarbon contacts and/or different free water levels, as illustrated in the following figure. Small differences in hydrocarbon contacts do not necessarily imply a cross-sealing fault because the capillary properties of the juxtaposed sands can create different hydrocarbon contacts even across a cross-leaking fault. Different free water levels do imply a cross-sealing fault.
[[file:evaluating-top-and-fault-seal_fig10-7.png|thumb|{{figure number|10-7}}See text for explanation.]]
==Different pressures==
Different pressures across a fault imply cross seal. In the figure below, wells 1 and 2 are separated by a cross-sealing fault. Well 2 encountered virgin pressures in contrast to the lower pressures in the main field.
[[file:evaluating-top-and-fault-seal_fig10-8.png|thumb|{{figure number|10-8}}See text for explanation.]]
==See also==
* [[Fault seal behavior]]
* [[Fault seal behavior basics]]
* [[Cross-leaking faults]]
* [[Dip-sealing faults]]
* [[Dip-leaking faults]]
* [[Controls on percent fill]]
==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
}}
A cross-sealing fault prevents communication of hydrocarbons between juxtaposed sands (reservoirs). Cross-sealing faults can be identified using the following criteria:
* Hydrocarbon-bearing sands against water-wet sands
* Different hydrocarbon contacts
* Different pressures
==Hydrocarbon against water==
A fault is cross sealing if it juxtaposes hydrocarbon-bearing sands with water-wet sands, as illustrated in the following figure. Both oil and gas are prevented from flowing into the sand in the hanging wall (R<sub>d</sub>) by the cross-sealing fault.
[[file:evaluating-top-and-fault-seal_fig10-6.png|thumb|{{figure number|10-6}}See text for explanation.]]
==Different hydrocarbon contacts==
A fault is also cross sealing if it juxtaposes sands with different hydrocarbon contacts and/or different free water levels, as illustrated in the following figure. Small differences in hydrocarbon contacts do not necessarily imply a cross-sealing fault because the capillary properties of the juxtaposed sands can create different hydrocarbon contacts even across a cross-leaking fault. Different free water levels do imply a cross-sealing fault.
[[file:evaluating-top-and-fault-seal_fig10-7.png|thumb|{{figure number|10-7}}See text for explanation.]]
==Different pressures==
Different pressures across a fault imply cross seal. In the figure below, wells 1 and 2 are separated by a cross-sealing fault. Well 2 encountered virgin pressures in contrast to the lower pressures in the main field.
[[file:evaluating-top-and-fault-seal_fig10-8.png|thumb|{{figure number|10-8}}See text for explanation.]]
==See also==
* [[Fault seal behavior]]
* [[Fault seal behavior basics]]
* [[Cross-leaking faults]]
* [[Dip-sealing faults]]
* [[Dip-leaking faults]]
* [[Controls on percent fill]]
==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]]