Seismic imaging of salt structures in the Gulf of Mexico

Ratcliff, Davis W.; Gray, Samuel H.; Whitmore, N.D.

doi:10.1190/1.1436876

Cited by 54 publications

(13 citation statements)

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“…Elastoplastic models have previously been applied to salt basin evolution and deformation modeling around salt (e.g., Schultz-Ela and Walsh, 2002;Schultz-Ela, 2003;Dirkzwager and Dooley, 2008). Plasticity will better simulate stress perturbations around salt bodies, which are known to involve plastic deformation in nature (e.g., Ratcliff et al, 1992;Davison et al, 2000b;Schultz-Ela, 2003).…”

Section: Analysis Of Model Resultsmentioning

confidence: 99%

Geomechanical modeling of stresses adjacent to salt bodies: Part 1—Uncoupled models

Luo¹,

Nikolinakou²,

Flemings³

et al. 2012

Bulletin

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We compare four approaches to geomechanical modeling of stresses adjacent to salt bodies. These approaches are distinguished by their use of elastic or elastoplastic constitutive laws for sediments surrounding the salt, as well as their treatment of fluid pressures in modeling. We simulate total stress in an elastic medium and then subtract an assumed pore pressure after calculations are complete; simulate effective stress in an elastic medium and use assumed pore pressure during calculations; simulate total stress in an elastoplastic medium, either ignoring pore pressure or approximating its effects by decreasing the internal friction angle; and simulate effective stress in an elastoplastic medium and use assumed pore pressure during calculations. To evaluate these approaches, we compare stresses generated by viscoelastic stress relaxation of a salt sphere. In all cases, relaxation causes the salt sphere to shorten vertically and expand laterally, producing extensional strains above and below the sphere and shortening against the sphere flanks. Deviatoric stresses are highest when sediments are assumed to be elastic, whereas plastic yielding in elastoplastic models places an upper limit on deviatoric stresses that the rocks can support, so stress perturbations are smaller. These comparisons provide insights into stresses around salt bodies and give geoscientists a basis for evaluating and comparing stress predictions.

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Section: Analysis Of Model Resultsmentioning

confidence: 99%

Geomechanical modeling of stresses adjacent to salt bodies: Part 1—Uncoupled models

Luo¹,

Nikolinakou²,

Flemings³

et al. 2012

Bulletin

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“…2A). The large amount of energy refracted by the vertical velocity gradient allows reflections from vertical structures to be as strong as those from horizontal structures (16 petroleum industry has developed techniques to image reflections from the steep sides of salt domes (17,18). Reflections have been observed from steeply dipping fault planes (16), but only Louie (19) has attempted to migrate the reflections, a necessary step in determining their subsurface location.…”

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confidence: 97%

Steep-Dip Seismic Imaging of the Shallow San Andreas Fault Near Parkfield

Hole

Catchings

Clair

et al. 2001

Science

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Seismic reflection and refraction images illuminate the San Andreas Fault to a depth of 1 kilometer. The prestack depth-migrated reflection image contains near-vertical reflections aligned with the active fault trace. The fault is vertical in the upper 0.5 kilometer, then dips about 70 degrees to the southwest to at least 1 kilometer subsurface. This dip reconciles the difference between the computed locations of earthquakes and the surface fault trace. The seismic velocity cross section shows strong lateral variations. Relatively low velocity (10 to 30%), high electrical conductivity, and low density indicate a 1-kilometer-wide vertical wedge of porous sediment or fractured rock immediately southwest of the active fault trace.

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“…If on the other hand strong diving waves are present, they can be reflected from the salt flank, recorded on the surface, and migrated by a two-way migration method, such as Kirchhoff migration (Ratcliff et al, 1991(Ratcliff et al, , 1992 or reverse time migration (RTM) (Baysal et al, 1983;McMechan, 1983;Whitmore, 1983). Even a one-way migration method can be modified (Hale et al, 1992) to incorporate diving waves for salt flank imaging.…”

Section: Introductionmentioning

confidence: 99%

Reverse time migration of prism waves for salt flank delineation

Dai¹,

Schuster

2013

SEG Technical Program Expanded Abstracts 2013

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SUMMARYIn this paper, we present a new reverse time migration method for imaging salt flanks with prism wave reflections. It consists of four steps: (1) migrating the seismic data with conventional RTM to give the RTM image; (2) using the RTM image as a reflectivity model to simulate source-side reflections with the Born approximation; (3) zero-lag correlation of the source-side reflection wavefields and receiver-side wavefields to produce the prism wave migration image; and (4) repeating steps 2 and 3 for the receiver-side reflections. An advantage of this method is that there is no need to pick the horizontal reflectors prior to migration of the prism waves. It also separately images the vertical structures at a different step to reduce crosstalk interference. The disadvantage of prism wave migration algorithm is that its computational cost is twice that of conventional RTM. The empirical results with a salt model suggest that prism wave migration can be an effective method for salt flank delineation in the absence of diving waves.

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Seismic imaging of salt structures in the Gulf of Mexico

Cited by 54 publications

References 0 publications

Geomechanical modeling of stresses adjacent to salt bodies: Part 1—Uncoupled models

Geomechanical modeling of stresses adjacent to salt bodies: Part 1—Uncoupled models

Steep-Dip Seismic Imaging of the Shallow San Andreas Fault Near Parkfield

Reverse time migration of prism waves for salt flank delineation

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