Hybrid Gridded Tomography

Jones, Ian F.; Sugrue, M.J.; Hardy, Pierre

doi:10.3997/1365-2397.2007013

Cited by 31 publications

(11 citation statements)

References 5 publications

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“…We performed top down iterations of tomographic velocity updating on the velocity model in order to derive a final depth interval velocity model for PSDM (Jones et al, 2007). The velocity model building was broken down into 10 model building units (MBUs).…”

Section: Model Building For Psdmmentioning

confidence: 99%

“…This gives correct ray paths at the seafloor, but suffers from the inaccuracies in 1D velocity picking involved in the creation of the field, and the result breaks down below the seafloor. Iterative depth domain tomographic velocity updating followed by PSDM is the best solution to the problem (Jones et al, 2007). This not only gives an accurate ray traced seafloor reflection, but also allows the deeper velocities to be determined based on ray traced analysis.…”

Section: Introductionmentioning

confidence: 99%

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Pre-stack depth migration for improved imaging under seafloor canyons: 2D case study of Browse Basin, Australia

Debenham

Westlake²

2014

Exploration Geophysics

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In the Browse Basin, as in many areas of the world, complex seafloor topography can cause problems with seismic imaging. This is related to complex ray paths, and sharp lateral changes in velocity. This paper compares ways in which 2D Kirchhoff imaging can be improved below seafloor canyons, using both time and depth domain processing.In the time domain, to improve on standard pre-stack time migration (PSTM) we apply removable seafloor static time shifts in order to reduce the push down effect under seafloor canyons before migration. This allows for better event continuity in the seismic imaging. However this approach does not fully solve the problem, still giving sub-optimal imaging, leaving amplitude shadows and structural distortion. Only depth domain processing with a migration algorithm that honours the paths of the seismic energy as well as a detailed velocity model can provide improved imaging under these seafloor canyons, and give confidence in the structural components of the exploration targets in this area. We therefore performed depth velocity model building followed by pre-stack depth migration (PSDM), the result of which provided a step change improvement in the imaging, and provided new insights into the area.

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Section: Model Building For Psdmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pre-stack depth migration for improved imaging under seafloor canyons: 2D case study of Browse Basin, Australia

Debenham

Westlake²

2014

Exploration Geophysics

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“…The statistical model described in this paper is based on the discrete layer velocity model representation and can be easily coupled with a layer -based tomographic inversion scheme. The challenge will be to incorporate an analogous model to gridded or hybrid velocity model representations [Jones et al, 2007] for complex geological structures, where the velocity regime is controlled by a combination of vertical compaction gradients and sharp velocity contrasts. 10-20-100-125 at seabed (sb), 10-20-100-125 at sb + 0.3 s, 8-15-100,120 at sb + 0.6 s, 5-10-90-110 at sb + 0.9 s, 3-8-50-70 at sb + 2.5 s Frequency -distance (f-x) deconvolution for random noise attenuation Amplitude-phase Inverse Q compensation = 200 Cosmetic sea noise mute preSDM/preSTM images with and without prestack amplitude shaping.…”

Section: Resultsmentioning

confidence: 99%

Uncertainty analysis of depth predictions from seismic reflection data using Bayesian statistics

Michelioudakis

Hobbs

Caiado

2018

Geophysical Journal International

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Estimating the depths of target horizons from seismic reflection data is an important task in exploration geophysics. To constrain these depths we need a reliable and accurate velocity model. Here, we build an optimum 2D seismic reflection data processing flow focused on pre-stack deghosting filters and velocity model building and apply Bayesian methods, including Gaussian process emulation and Bayesian History Matching (BHM), to estimate the uncertainties of the depths of key horizons near the borehole DSDP-258 located in the Mentelle Basin, south west of Australia, and compare the results with the drilled core from that well. Following this strategy, the tie between the modelled and observed depths from DSDP-258 core was in accordance with the ± 2σ posterior credibility intervals and predictions for depths to key horizons were made for the two new drill sites, adjacent the existing borehole of the area. The probabilistic analysis allowed us to generate multiple realizations of pre-stack depth migrated images, these can be directly used to better constrain interpretation and identify potential risk at drill sites. The method will be applied to constrain the drilling targets for the upcoming International Ocean Discovery Program (IODP), leg 369.

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“…However, a more fl exible route is to adopt a hybrid approach in which we combine the benefi ts of both schemes: the ability of a gridded route to capture the subtle lateral velocity variation inherent to some strata while keeping the sharp vertical breaks occasionally present in the earth (such as at chalk and salt boundaries (Jones et al, 2007). However, a more fl exible route is to adopt a hybrid approach in which we combine the benefi ts of both schemes: the ability of a gridded route to capture the subtle lateral velocity variation inherent to some strata while keeping the sharp vertical breaks occasionally present in the earth (such as at chalk and salt boundaries (Jones et al, 2007).…”

Section: Hybrid Approachesmentioning

confidence: 99%