Changes

[[file:migration-of-petroleum_fig7-8.png|300px|thumb|{{figure number|1}}Illustration of what happens when seals leak from traps with gas caps. After Schowalter.<ref name=ch07r12>Schowalter, T., T., 1979, [http://archives.datapages.com/data/bulletns/1977-79/data/pg/0063/0005/0700/0723.htm Mechanics of secondary hydrocarbon migration and entrapment]: AAPG Bulletin, vol. 63, p. 723–760.</ref>]]

[[file:migration-of-petroleum_fig7-8.png|300px|thumb|{{figure number|1}}Illustration of what happens when seals leak from traps with gas caps. After Schowalter.<ref name=ch07r12>Schowalter, T., T., 1979, [http://archives.datapages.com/data/bulletns/1977-79/data/pg/0063/0005/0700/0723.htm Mechanics of secondary hydrocarbon migration and entrapment]: AAPG Bulletin, vol. 63, p. 723–760.</ref>]]

In traps with gas caps, the buoyancy of the gas and oil column can exceed the breakthrough pressure of the seal prior to the trap being filled to the spill point. If this happens, the trap will leak through the seal and preferentially lose the gas phase. This situation (deep oil, shallow gas) is observed but is opposite to the expected sequence of entrapment due to [[maturation]] (oil migrates first, then gas). [[:file:migration-of-petroleum_fig7-8.png|Figure 1]] illustrates what happens when seals leak from traps with gas caps.

In [[trap]]s with [http://www.glossary.oilfield.slb.com/en/Terms/g/gas_cap.aspx gas caps], the [[Buoyancy pressure|buoyancy]] of the gas and oil column can exceed the breakthrough pressure of the seal prior to the trap being filled to the spill point. If this happens, the trap will leak through the seal and preferentially lose the gas phase. This situation (deep oil, shallow gas) is observed but is opposite to the expected sequence of entrapment due to [[maturation]] (oil migrates first, then gas). [[:file:migration-of-petroleum_fig7-8.png|Figure 1]] illustrates what happens when seals leak from traps with gas caps.

==Differential entrapment==

==Differential entrapment==