Seismic imaging of salt structures in the Gulf of Mexico

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

doi:10.1190/1.1888720

Cited by 11 publications

(11 citation statements)

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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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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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“…Thus, by simply mapping the contact between these coherent, 'overburden' reflections and incoherent, 'salt' reflections, the location of the salt-sediment interface would be misinterpreted by several hundreds of metres, the width of the diapir stem would be underestimated and the overall geometry of the salt diapir would be wholly incorrect (Fig. 3) (see Ratcliffe et al 1992;Reilly 1995;Kessler et al 1996;o'Brien 2005;Farmer et al 2006). Although advanced, reverse time migration (RTM) and turning wave post-stack depth migration (PSDM) techniques may provide relatively accurate images of steep-sided salt structures (e.g.…”

Section: Seismic Imaging Of Steep-sided Salt Structures; Implicationsmentioning

confidence: 95%

“…Although advanced, reverse time migration (RTM) and turning wave post-stack depth migration (PSDM) techniques may provide relatively accurate images of steep-sided salt structures (e.g. Ratcliffe et al 1992;Farmer et al 2006), many interpreters are still restricted to using 'standard', pre-or post-stack depth-migrated seismic reflection volumes. As we have demonstrated, these types of seismic data may lead interpreters to incorrectly interpret that a salt structure has a 'tear-drop' shape owing to post-emplacement, inversion-related basin contraction.…”

Section: Seismic Imaging Of Steep-sided Salt Structures; Implicationsmentioning

confidence: 99%

Origin of an anhydrite sheath encircling a salt diapir and implications for the seismic imaging of steep-sided salt structures, Egersund Basin, Northern North Sea

Jackson

Lewis

2012

JGS

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The ingress of meteoric fluids into the crests of salt structures typically results in the formation of anhydrite-dominated caprock. The migration of connate fluids up the margins of salt structures has also been documented, although the products related to this are rarely sampled in the deep subsurface. We use 3D seismic reflection and borehole data to document the geometry and lithology of a salt diapir. Seismic data suggest that a weld is developed along the diapir stem, although borehole data indicate that the stem consists of an inner, c. 1500 m thick, halite-dominated zone, and an outer, c. 250 m thick, anhydrite-dominated 'sheath'. The anhydrite may have formed early in the basin history, as a depositional anhydrite or crestal caprock. An alternative interpretation is that the anhydrite represents 'lateral caprock', which formed late in the basin history in response to the migration of NaCl-poor fluid up the margins of the diapir and dissolution of halite. The possibility that lateral caprock may form adjacent to salt structures has implications for understanding the patterns and vigour of groundwater flow in sedimentary basins. Furthermore, our study shows the margins of steep-sided salt structures may be misidentified by several hundred metres if time-migrated seismic reflection data are used.

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“…Seismic wavefield imaging of Earth's interior across scales from ~7 km underneath the oceans to ~70 km beneath the Andes and Tibet 7,8 . As another example, the Gulf of Mexico contains high-wave-speed salt domes with complex geometries embedded in slow-wave-speed sediments 9 , and this type of environment cannot be modelled based on theories that invoke perturbations to smooth 'background' models. The goal of seismic full-waveform inversion (FWI) is to use all information contained in seismographic recordings -that is, every wiggle in a seismogram -to determine the structure of Earth's interior, constrained by the physics of seismicwave propagation.…”

Section: Surface Wavesmentioning

confidence: 99%

Seismic wavefield imaging of Earth’s interior across scales

Tromp

2019

Nat Rev Earth Environ

113

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Seismic full-waveform inversion (FWI) for imaging Earth's interior was introduced in the late 1970s. Its ultimate goal is to use all of the information in a seismogram to understand the structure and dynamics of Earth, such as hydrocarbon reservoirs, the nature of hotspots and the forces behind plate motions and earthquakes. Thanks to developments in high-performance computing and advances in modern numerical methods in the past 10 years, 3D FWI has become feasible for a wide range of applications and is currently used across nine orders of magnitude in frequency and wavelength. A typical FWI workflow includes selecting seismic sources and a starting model, conducting forward simulations, calculating and evaluating the misfit, and optimizing the simulated model until the observed and modelled seismograms converge on a single model. This method has revealed Pleistocene ice scrapes beneath a gas cloud in the Valhall oil field, overthrusted Iberian crust in the western Pyrenees mountains, deep slabs in subduction zones throughout the world and the shape of the African superplume. The increased use of multi-parameter inversions, improved computational and algorithmic efficiency , and the inclusion of Bayesian statistics in the optimization process all stand to substantially improve FWI, overcoming current computational or data-quality constraints. In this Technical Review, FWI methods and applications in controlled-source and earthquake seismology are discussed, followed by a perspective on the future of FWI, which will ultimately result in increased insight into the physics and chemistry of Earth's interior.

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Seismic imaging of salt structures in the Gulf of Mexico

Cited by 11 publications

References 0 publications

Reverse time migration of prism waves for salt flank delineation

Reverse time migration of prism waves for salt flank delineation

Origin of an anhydrite sheath encircling a salt diapir and implications for the seismic imaging of steep-sided salt structures, Egersund Basin, Northern North Sea

Seismic wavefield imaging of Earth’s interior across scales

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