Difference between revisions of "Displacement pressure: theory vs. reality"

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Rarely is the actual column of trapped hydrocarbon compared with the prediction from measured displacement pressures. Empirical studies are needed because simple, idealized laboratory experiments show significant errors between the predicted and observed hydrocarbon column heights.<ref name=ch10r12>CatalanXiaown, L., F., Chatzis, I., Dullien, F., A., L., 1992, An experimental study of secondary oil [[migration]]: AAPG Bulletin, vol. 76, no. 5, p. 638–650.</ref> These experiments at best have column heights 19–23% larger than predicted. At worst, they are 125–217% larger than predicted. (The larger differences are probably the result of short equilibration times.)
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Rarely is the actual column of trapped hydrocarbon compared with the prediction from measured [[displacement pressure]]s. Empirical studies are needed because simple, idealized laboratory experiments show significant errors between the predicted and observed [[hydrocarbon column]] heights.<ref name=ch10r12>Catalan, L., F. Xiaown, I. Chatzis, and F. A. L. Dullien, 1992, [http://archives.datapages.com/data/bulletns/1992-93/data/pg/0076/0005/0000/0638.htm An experimental study of secondary oil migration]: AAPG Bulletin, vol. 76, no. 5, p. 638–650.</ref> These experiments at best have column heights 19–23% larger than predicted. At worst, they are 125–217% larger than predicted. (The larger differences are probably the result of short equilibration times.)
  
 
==Benton field==
 
==Benton field==
Benton field, Illinois, in one example in which the trapped column heights match the measured displacement pressure of the top seal.<ref name=ch10r78>Sneider, R., M., Bolger, G., 1993, Estimating seals from wireline logs of clastic seals and reservoir intervals, in Ebanks, J., Kaldi, J., Vavra, C., eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg Research conference, unpublished abstract.</ref> Measured displacement pressures predict the top seal is capable of trapping 29–34 m (94–110 ft) of hydrocarbon. The actual column of hydrocarbon in the field in the Tar Springs reservoir is [[length::29 m]] [[depth::(95 ft]]).
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Benton field, Illinois, in one example in which the trapped column heights match the measured [[Top seal displacement pressure|displacement pressure of the top seal]].<ref name=ch10r78>Sneider, R. M., and G. Bolger, 1993, Estimating seals from wireline logs of clastic seals and reservoir intervals, in J. Ebanks, J. Kaldi, and C. Vavra, eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg Research conference, unpublished abstract.</ref> Measured displacement pressures predict the top seal is capable of trapping 29–34 m (94–110 ft) of hydrocarbon. The actual column of hydrocarbon in the field in the Tar Springs Formation reservoir is [[length::29 m]] [[depth::(95 ft]]).
  
==Bodalla south field==
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==Bodalla South field==
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 pathway]]s 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> The following cross section 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. 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]].
 
  
[[file:evaluating-top-and-fault-seal_fig10-53.png|thumb|{{figure number|10-53}}After .<ref name=ch10r6 /> Copyright: Marine and Petroleum Geology.]]
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[[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.]]
  
==Top seal quality variation==
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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.
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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.
  
 
==See also==
 
==See also==
* [[Pitfalls and limitations of estimating seal capacity]]
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* [[Seal capacity: pitfalls and limitations of estimation]]
* [[Difficulty of characterizing Pd of a seal]]
 
 
* [[Saturations required for hydrocarbon flow]]
 
* [[Saturations required for hydrocarbon flow]]
 
* [[Seal capacity of breached and hydrocarbon-wet seals]]
 
* [[Seal capacity of breached and hydrocarbon-wet seals]]
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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]]
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[[Category:Treatise Handbook 3]]

Latest revision as of 13:36, 1 April 2022

Exploring for Oil and Gas Traps
Series Treatise in Petroleum Geology
Part Predicting the occurrence of oil and gas traps
Chapter Evaluating top and fault seal
Author Grant M. Skerlec
Link Web page
Store AAPG Store

Rarely is the actual column of trapped hydrocarbon compared with the prediction from measured displacement pressures. Empirical studies are needed because simple, idealized laboratory experiments show significant errors between the predicted and observed hydrocarbon column heights.[1] These experiments at best have column heights 19–23% larger than predicted. At worst, they are 125–217% larger than predicted. (The larger differences are probably the result of short equilibration times.)

Benton field

Benton field, Illinois, in one example in which the trapped column heights match the measured displacement pressure of the top seal.[2] Measured displacement pressures predict the top seal is capable of trapping 29–34 m (94–110 ft) of hydrocarbon. The actual column of hydrocarbon in the field in the Tar Springs Formation reservoir is length::29 m depth::(95 ft).

Bodalla South field

Figure 1 Top seal and oil accumulations in the Bodalla South field, Eromanga basin, Australia.[3] 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.[3] 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.[3] More empirical studies are needed.

See also

References

  1. Catalan, L., F. Xiaown, I. Chatzis, and F. A. L. Dullien, 1992, An experimental study of secondary oil migration: AAPG Bulletin, vol. 76, no. 5, p. 638–650.
  2. Sneider, R. M., and G. Bolger, 1993, Estimating seals from wireline logs of clastic seals and reservoir intervals, in J. Ebanks, J. Kaldi, and C. Vavra, eds., Seals and Traps: A Multidisciplinary Approach: AAPG Hedberg Research conference, unpublished abstract.
  3. 3.0 3.1 3.2 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

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