Controls of permeability on the mechanical evolution of shortening basins

R. Foroozan, Derek Elsworth, P. B. Flemings, F. Bilotti, S. Muhuri

Research output: Contribution to conferencePaper

Abstract

We follow the evolution of faulting in an idealized prismatic basin during lateral shortening as a result of poromechanical interactions. This includes the deformation-induced generation (compaction) and dissipation (hydraulic fracturing) of pore fluid pressures and the resulting natural evolution an underlying decollement and fault structures. Modeling is capable of representing the form of fault structures that may develop within a basin as a result of shortening. Thrust faulting develops as overpressures evolve to trigger failure. A decollement forms within the system at the boundary with the substrate where overpressures drive failure in extension, by hydrofracturing. Failure in the basin overlaying the decollement initiates from these overpressures at the decollement. Where the evolution of permeability with shear strain is artificially suppressed, pervasive shear develops throughout the basin depth as fluid pressures are pegged everywhere to the lithostat. Conversely, where permeability is allowed to increase with shear strain/rupture, faulting first nucleates at the decollement and localizes upwards through the section. Correspondingly, permeability evolution with shear is an important, likely crucial, feedback in promoting localization, as failure is concentrated at the limits of the upward-migrating fault-tip. Elevated pore pressures approaching the lithostat are localized at the hanging wall boundary of the faults. As faults extend, horsts and graben are ultimately isolated, and evolve with distinctive surface topography and separate pore pressure signatures. Horsts have elevated fluid pressures and reduced effective stresses at their core, and graben the converse.

Original languageEnglish (US)
StatePublished - Dec 1 2010
Event44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium - Salt Lake City, UT, United States
Duration: Jun 27 2010Jun 30 2010

Other

Other44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium
CountryUnited States
CitySalt Lake City, UT
Period6/27/106/30/10

Fingerprint

Faulting
decollement
Pore pressure
Shear strain
permeability
overpressure
fluid pressure
Fluids
pore pressure
faulting
basin
horst
shear strain
Hydraulic fracturing
graben
Surface topography
Compaction
Feedback
hanging wall
effective stress

All Science Journal Classification (ASJC) codes

  • Geology
  • Geotechnical Engineering and Engineering Geology

Cite this

Foroozan, R., Elsworth, D., Flemings, P. B., Bilotti, F., & Muhuri, S. (2010). Controls of permeability on the mechanical evolution of shortening basins. Paper presented at 44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium, Salt Lake City, UT, United States.
Foroozan, R. ; Elsworth, Derek ; Flemings, P. B. ; Bilotti, F. ; Muhuri, S. / Controls of permeability on the mechanical evolution of shortening basins. Paper presented at 44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium, Salt Lake City, UT, United States.
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Foroozan, R, Elsworth, D, Flemings, PB, Bilotti, F & Muhuri, S 2010, 'Controls of permeability on the mechanical evolution of shortening basins' Paper presented at 44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium, Salt Lake City, UT, United States, 6/27/10 - 6/30/10, .

Controls of permeability on the mechanical evolution of shortening basins. / Foroozan, R.; Elsworth, Derek; Flemings, P. B.; Bilotti, F.; Muhuri, S.

2010. Paper presented at 44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium, Salt Lake City, UT, United States.

Research output: Contribution to conferencePaper

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N2 - We follow the evolution of faulting in an idealized prismatic basin during lateral shortening as a result of poromechanical interactions. This includes the deformation-induced generation (compaction) and dissipation (hydraulic fracturing) of pore fluid pressures and the resulting natural evolution an underlying decollement and fault structures. Modeling is capable of representing the form of fault structures that may develop within a basin as a result of shortening. Thrust faulting develops as overpressures evolve to trigger failure. A decollement forms within the system at the boundary with the substrate where overpressures drive failure in extension, by hydrofracturing. Failure in the basin overlaying the decollement initiates from these overpressures at the decollement. Where the evolution of permeability with shear strain is artificially suppressed, pervasive shear develops throughout the basin depth as fluid pressures are pegged everywhere to the lithostat. Conversely, where permeability is allowed to increase with shear strain/rupture, faulting first nucleates at the decollement and localizes upwards through the section. Correspondingly, permeability evolution with shear is an important, likely crucial, feedback in promoting localization, as failure is concentrated at the limits of the upward-migrating fault-tip. Elevated pore pressures approaching the lithostat are localized at the hanging wall boundary of the faults. As faults extend, horsts and graben are ultimately isolated, and evolve with distinctive surface topography and separate pore pressure signatures. Horsts have elevated fluid pressures and reduced effective stresses at their core, and graben the converse.

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M3 - Paper

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Foroozan R, Elsworth D, Flemings PB, Bilotti F, Muhuri S. Controls of permeability on the mechanical evolution of shortening basins. 2010. Paper presented at 44th US Rock Mechanics Symposium and the 5th US/Canada Rock Mechanics Symposium, Salt Lake City, UT, United States.