The Benefits of Multi-azimuth Depth Migration over the Tidepole Field, North West Shelf, Australia

See, None William R. Dickinson, Donald R.; Ridsdill-Smith, Tom

doi:10.3997/2214-4609.201400652

Cited by 7 publications

(12 citation statements)

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“…A VSP survey was also acquired over the Stybarrow Field and did not show any observable SAA across this geologic interval [ Pevzner et al ., ]. The Tidepole 3‐D seismic survey was acquired toward the west of the Dampier Subbasin (Figure ) and does, however, observe strong SAA with consistent ϕ across a shallow, thin package that corresponds to the quartz sediments of the Bare Formation (Figure ) [ Dickinson and Ridsdill‐Smith , ].…”

Section: Resultsmentioning

confidence: 99%

Stress‐induced seismic azimuthal anisotropy in the upper crust across the North West Shelf, Australia

Gavin

Lumley

2016

JGR Solid Earth

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Seismic azimuthal anisotropy (SAA) is observed in many areas of the Earth, and fast polarized directions (ϕ) have been mapped using earthquake surface waves and teleseismic S wave splitting over large regional and tectonic scales. Higher‐resolution petroleum exploration data, including 3‐D seismic surveys and dipole shear logs, often exhibit azimuthal anisotropy; however, we are unaware of any published studies mapping SAA from exploration‐scale data to study large‐scale regional and tectonic SAA trends. The physical mechanisms causing SAA in earthquake data are a subject of great interest; comparing regional ϕ trends to the higher‐resolution exploration trends may help understand these mechanisms. We present a SAA analysis using seismic exploration data across the North West Shelf (NWS) of Australia. We map the fast polarization directions ϕ from 34 dipole shear logs and two 3‐D seismic surveys and compare them to in situ maximum horizontal stress orientations (σH). Our results show that the ϕ and σH trends correlate across a geographical area spanning almost 2000 km and are similar to published results in the region from earthquake seismology. These results suggest that differential horizontal stress is the likely mechanism causing SAA at a wide range of spatial scales on the NWS of Australia. We also show that SAA is not observed at exploration scales in some areas of the NWS and propose a lithology‐dependent stress sensitivity model in which SAA is strongest in clean, unconsolidated quartz‐dominated sandstones and weaker or nonexistent in well‐consolidated cemented rocks and shale‐dominated sediments.

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Section: Resultsmentioning

confidence: 99%

Stress‐induced seismic azimuthal anisotropy in the upper crust across the North West Shelf, Australia

Gavin

Lumley

2016

JGR Solid Earth

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“…The presence of orthorhombic anisotropy poses challenges in wide azimuth imaging. Analysis of multi-azimuth (MAZ) data often reveals noticeable fluctuations in moveout between different acquisition directions, preventing constructive summation of MAZ images (Dickinson et al 2010). VTI effects can also cause well misties and higher order moveout.…”

Section: Introductionmentioning

confidence: 99%

Multi-Azimuth Seismic Data Imaging in the Presence of Orthorhombic Anisotropy

et al. 2013

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Orthorhombic anisotropy is considered to be the simplest realistic symmetry for many geophysical problems. Orthorhombic anisotropy exhibits both HTI (Horizontal Transverse Anisotropy) and VTI (Vertical Transverse Anisotropy) effects, making seismic velocity varying with azimuthal direction as well as polar direction. In many cases, these effects are important by themselves and can be a target of special studies. The presence of orthorhombic anisotropy poses challenges in wide azimuth imaging which has been rapidly developed for better illumination, better imaging, and better multiple elimination. Analysis of multi-azimuth (MAZ) data often reveals noticeable fluctuations in moveout between different acquisition directions, preventing constructive summation of MAZ images due to the azimuthal dependency nature of wave propagation in orthorhombic medium. On the other hand, the co-existing VTI effects of orthorhombic anisotropy can also cause well misties and higher order moveout. Orthorhombic anisotropy can take into account the co-existing HTI/VTI effects. We have developed an approach for imaging in the presence of orthorhombic anisotropy, including orthorhombic velocity analysis and orthorhombic migration. Following Tsvankin's work, we put forward a ray tracing approach suitable for both weak and strong anisotropy which applies to both Kirchhoff and Beam PSDM. Aimed at the challenge in orthorhombic anisotropy model building, we have developed a practical workflow which combines the co-existing HTI/VTI anisotropy estimated through multi-azimuth tomography to form the orthorhombic model. In this paper, we first describe our approach for imaging in the presence of orthorhombic anisotropy, including the newly developed orthorhombic ray tracing method and the newly developed practical method for orthorhombic anisotropy model building. We then demonstrate with both synthetic and real data from offshore Australia that our approach can successfully take into account the co-existing HTI/VTI effects, reduce the structural discrepancies between seismic images built for different azimuths, hence produce constructive summation of MAZ dataset, resolve well mistie to match with geology, and deliver a step-change in the final seismic image quality.

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“…Analysis of multi-azimuth (MAZ) data often reveals noticeable fluctuations in moveout between different acquisition directions, preventing constructive summation of MAZ images (Dickinson et al 2010). VTI effects can also cause well misties and higher order moveout.…”

Section: Introductionmentioning

confidence: 99%

Prestack depth imaging of multi-azimuth seismic data in the presence of orthorhombic anisotropy

Xie¹,

Birdus²,

Sun³

et al. 2012

ASEG Extended Abstracts

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The Benefits of Multi-azimuth Depth Migration over the Tidepole Field, North West Shelf, Australia

Cited by 7 publications

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Stress‐induced seismic azimuthal anisotropy in the upper crust across the North West Shelf, Australia

Stress‐induced seismic azimuthal anisotropy in the upper crust across the North West Shelf, Australia

Multi-Azimuth Seismic Data Imaging in the Presence of Orthorhombic Anisotropy

Prestack depth imaging of multi-azimuth seismic data in the presence of orthorhombic anisotropy

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