Changes

[[file:evaluating-top-and-fault-seal_fig10-53.png|300px||thumb|{{figure number|1}}Top seal and oil accumulations in the Bodalla South field, Eromanga basin, Australia.<ref name=ch10r6 /> Copyright: Marine and Petroleum Geology.]]

[[file:evaluating-top-and-fault-seal_fig10-53.png|300px||thumb|{{figure number|1}}Top seal and oil accumulations in the Bodalla South field, Eromanga basin, Australia.<ref name=ch10r6 /> Copyright: Marine and Petroleum Geology.]]

The Bodalla South field, Eromanga Basin, Australia, has short oil columns—less than [[length::12 m]] high—that appear to be limited by the displacement pressure of the top seal.<ref name=ch10r6>Boult, P. J., 1993, Membrane seal and tertiary migration pathways in the Bodalla South oilfield, Eronmanga Basin, Australia: Marine and Petroleum Geology, vol. 10, no. 1, p. 3–13., 10., 1016/0264-8172(93)90095-A</ref> [[:file:evaluating-top-and-fault-seal_fig10-53.png|Figure 1]] shows the top seal and oil accumulations. The top seal, the Birkhead Formation, consists of fluvial channel and point bar deposits as well as more shale-prone levee bank, crevasse splay, floodplain, and coal swamp facies. (See [[Lithofacies and environmental analysis of clastic depositional systems]].)  Measured displacement pressures of the top seal have an average range of 150–200 psi (air-mercury) and can seal 10.86–12.64 m of oil. The maximum height of the actual trapped oil column is [[depth::11.25 m]].

The Bodalla South field, Eromanga Basin, Australia, has short oil columns—less than [[length::12 m]] high—that appear to be limited by the displacement pressure of the top seal.<ref name=ch10r6>Boult, P. J., 1993, Membrane seal and tertiary migration pathways in the Bodalla South oilfield, Eronmanga Basin, Australia: Marine and Petroleum Geology, vol. 10, no. 1, p. 3–13., 10., 1016/0264-8172(93)90095-A</ref> [[:file:evaluating-top-and-fault-seal_fig10-53.png|Figure 1]] shows the top seal and oil accumulations. The top seal, the Birkhead Formation, consists of fluvial channel and point bar deposits as well as more shale-prone levee bank, crevasse splay, floodplain, and [[coal]] swamp facies. (See [[Lithofacies and environmental analysis of clastic depositional systems]].)  Measured displacement pressures of the top seal have an average range of 150–200 psi (air-mercury) and can seal 10.86–12.64 m of oil. The maximum height of the actual trapped oil column is [[depth::11.25 m]].

Although predicted and observed data apparently agree, units within the top seal may be able to trap much greater oil columns. Measured displacement pressures of the shaly overbank facies are greater than [[pressure::3000 psi]] (air-mercury). These facies are not thought to be effective seals because they are either thin or lack lateral continuity.<ref name=ch10r6 /> More empirical studies are needed.

Although predicted and observed data apparently agree, units within the top seal may be able to trap much greater oil columns. Measured displacement pressures of the shaly overbank facies are greater than [[pressure::3000 psi]] (air-mercury). These facies are not thought to be effective seals because they are either thin or lack lateral continuity.<ref name=ch10r6 /> More empirical studies are needed.