Overcoming thrust‐belt imaging problems in Magdalena Valley, Colombia

Gittins, Jon; Vestrum, Rob; Gillcrist, Ralph

doi:10.1190/1.1839685

Cited by 4 publications

(1 citation statement)

References 2 publications

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“…The velocity model is simply a horizontal reflector at the base of a homogeneous dipping anisotropic layer, 2000 m in vertical thickness, with an axis of symmetry tilted at 15° from the vertical. The anisotropic parameters used for the overburden in these tests were chosen to be ɛ= 0.12 and δ= 0.03, which are commonly used values in thrust‐belt anisotropic depth migration (e.g., Vestrum 2002; Gittins, Vestrum and Gillcrist 2004). Figure 2 shows minimum‐traveltime raypaths for offsets ranging from 0–4000 metres for this model.…”

Section: Raytrace Modellingmentioning

confidence: 99%

Reflection point sideslip and smear in imaging below dipping anisotropic media

Vestrum¹,

Lawton²

2010

Geophysical Prospecting

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A B S T R A C TDipping anisotropic clastic strata are ubiquitous in fold and thrust belts. Geological structures below these strata will be mispositioned laterally and vertically on seismic images if we do not properly correct for seismic anisotropy during migration. The magnitude of this lateral mispositioning of a target structure varies with source-receiver offset, so reflection points will be smeared in the final stacked image. Raytracing demonstrates the lateral-position and smear phenomena when imaging structures below tilted transversely isotropic media. Analysis of the raytracing results predicts the quantity of lateral-position error and reflection-point smear on a seismic image. We created numerical-model seismic data to show reflection-point smear on synthetic seismic images and to evaluate the accuracy of the predictions from raytracing.

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Section: Raytrace Modellingmentioning

confidence: 99%

Reflection point sideslip and smear in imaging below dipping anisotropic media

Vestrum¹,

Lawton²

2010

Geophysical Prospecting

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Sideslip and smear beneath dipping transversely isotropic strata

Vestrum

Vermeulen

2004

SEG Technical Program Expanded Abstracts 2004

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Acoustic wave propagation in tilted transversely isotropic media: Incorporating topography

Shragge

2016

GEOPHYSICS

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Simulating two-way acoustic wavefield propagation directly from a free-surface boundary in the presence of topography remains a computational challenge for applications of reverse time migration (RTM) or full-waveform inversion (FWI). For land-seismic settings involving heavily reworked geology (e.g., fold and thrust belts), two-way wavefield propagation operators should also handle commonly observed complex anisotropy including tilted transversely isotropic (TTI) media. To address these issues, I have extended a system of coupled partial differential equations used to model 3D acoustic TTI wave propagation in Cartesian coordinates to more generalized 3D geometries, including a deformed computational mesh with a domain boundary conformal to free-surface topography. A generalized curvilinear transformation is used to specify a system of equations governing 3D acoustic TTI wave propagation in the “topographic” coordinate system. The developed finite-difference time-domain numerical solution adapts existing Cartesian TTI operators to this more generalized geometry with little additional computational overhead. Numerical evaluations illustrate that 2D and 3D impulse responses are well-matched to those simulated on Cartesian meshes and analytic traveltimes for homogeneous elliptical TTI media. Accordingly, these generalized acoustic TTI propagators and their numerical adjoints are useful for undertaking most RTM or FWI applications using computational domains conforming to free-surface topography.

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Overcoming thrust‐belt imaging problems in Magdalena Valley, Colombia

Cited by 4 publications

References 2 publications

Reflection point sideslip and smear in imaging below dipping anisotropic media

Reflection point sideslip and smear in imaging below dipping anisotropic media

Sideslip and smear beneath dipping transversely isotropic strata

Acoustic wave propagation in tilted transversely isotropic media: Incorporating topography

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