Difference between revisions of "Cross-sealing fault"
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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 = 10-10 |
| − | | topg = 10- | + | | topg = 10-11 |
| 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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==Hydrocarbon against water== | ==Hydrocarbon against water== | ||
| − | A fault is cross sealing if it juxtaposes hydrocarbon-bearing sands with water-wet sands | + | <gallery mode=packed heights=200px widths=200px> |
| + | file:evaluating-top-and-fault-seal_fig10-6.png|{{figure number|1}}A fault is cross sealing if it juxtaposes hydrocarbon-bearing sands with water-wet sands. | ||
| + | file:evaluating-top-and-fault-seal_fig10-7.png|{{figure number|2}}A fault is cross sealing if it juxtaposes sands with different hydrocarbon contacts and/or different free water levels. | ||
| + | file:evaluating-top-and-fault-seal_fig10-8.png|{{figure number|3}}Two wells separated by a cross-sealing fault. Well 2 encountered virgin pressures in contrast to the lower pressures in the main field. | ||
| + | </gallery> | ||
| − | [[file:evaluating-top-and-fault-seal_fig10-6.png| | + | A fault is cross sealing if it juxtaposes hydrocarbon-bearing sands with water-wet sands, as illustrated in [[:file:evaluating-top-and-fault-seal_fig10-6.png|Figure 1]]. Both oil and gas are prevented from flowing into the sand in the hanging wall (R<sub>d</sub>) by the cross-sealing fault. |
==Different hydrocarbon contacts== | ==Different hydrocarbon contacts== | ||
| − | |||
| − | [[file:evaluating-top-and-fault-seal_fig10-7.png| | + | A fault is also cross sealing if it juxtaposes sands with different hydrocarbon contacts and/or different free water levels, as illustrated in [[:file:evaluating-top-and-fault-seal_fig10-7.png|Figure 2]]. 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. |
==Different pressures== | ==Different pressures== | ||
| − | |||
| − | [[file:evaluating-top-and-fault-seal_fig10-8.png| | + | Different pressures across a fault imply cross seal. In [[:file:evaluating-top-and-fault-seal_fig10-8.png|Figure 3]], 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. |
==See also== | ==See also== | ||
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* [[Dip-sealing faults]] | * [[Dip-sealing faults]] | ||
* [[Dip-leaking faults]] | * [[Dip-leaking faults]] | ||
| − | * [[ | + | * [[Percent fill: controlling factors]] |
==External links== | ==External links== | ||
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[[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 21:31, 24 March 2022
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
Figure 1 A fault is cross sealing if it juxtaposes hydrocarbon-bearing sands with water-wet sands.
Figure 2 A fault is cross sealing if it juxtaposes sands with different hydrocarbon contacts and/or different free water levels.
Figure 3 Two wells separated by a cross-sealing fault. Well 2 encountered virgin pressures in contrast to the lower pressures in the main field.
A fault is cross sealing if it juxtaposes hydrocarbon-bearing sands with water-wet sands, as illustrated in Figure 1. Both oil and gas are prevented from flowing into the sand in the hanging wall (Rd) by the cross-sealing fault.
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 Figure 2. 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.
Different pressures
Different pressures across a fault imply cross seal. In Figure 3, 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.
See also
External links
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