Addressing anisotropy in 3-D prestack depth migration: A case study from the Southern North Sea

Hawkins, Keith; Leggott, Richard; Williams, Geoffrey Lee; Kat, Herman

doi:10.1190/1.1438988

Cited by 13 publications

(5 citation statements)

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“…The biggest challenge was related to the fact that we already know from the surface seismic survey that this geological medium has very low anisotropy strength, and estimated anisotropy parameters were very low; however, these parameters have a significant impact on seismic processing and migration. This accurate information about local anisotropy could improve reprocessing of seismic data in the future, especially model building for depth migration [6]. The obtained results showed that combining the advanced processing of challenging walkaway VSP data with detailed data analysis of P-wave-only inversion gives additional helpful reservoir information that can be used to make interpretation more accurate when other surveys produce poor quality results and even if anisotropy is relatively low.…”

Section: Introductionmentioning

confidence: 91%

P-Wave-Only Inversion of Challenging Walkaway VSP Data for Detailed Estimation of Local Anisotropy and Reservoir Parameters: A Case Study of Seismic Processing in Northern Poland

2021

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In this paper, we present a detailed analysis of walkaway vertical seismic profiling (VSP) data, which can be used to obtain Thomsen parameters using P-wave-only inversion. Data acquisition took place in difficult field conditions, which influenced the quality of the data. Therefore, this paper also shows a seismic data processing scheme that allows the estimation of correct polarization angles despite poor input data quality. Moreover, we showed that it is possible to obtain reliable and detailed values of Thomsen’s anisotropy parameters for data that are challenging due to extremely difficult field conditions during acquisition and the presence of an overburden of salt and anhydrite (Zechstein formation). This complex is known for its strong seismic signal-attenuating properties. We designed a special processing workflow with a signal-matching procedure that allows reliable estimation of polarization angles for low-quality data. Additionally, we showed that P-wave-only inversion for the estimation of local anisotropy parameters can be used as valuable additional input for detailed interpretation of geological media, even if anisotropy is relatively low.

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Section: Introductionmentioning

confidence: 91%

P-Wave-Only Inversion of Challenging Walkaway VSP Data for Detailed Estimation of Local Anisotropy and Reservoir Parameters: A Case Study of Seismic Processing in Northern Poland

2021

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“…The accuracy of transverse anisotropy parameters determines the accuracy of depth matching of seismic data with well information. The difference between horizontal and vertical velocities can be determined better with long offsets, although walkaway VSP information and other well data would be helpful or even mandatory as well (Hawkins et al, 2001;Hawkins et al, 2002;Robein, 2010).…”

Section: Determine Maximum Offsetmentioning

confidence: 98%

3D Seismic Survey Design, Second edition

Vermeer¹

2012

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“…Secondly, we estimate the effective Thomsen's (1986) parameter 5 from the mismatches between effective P-wave velocities derived from surface seismic data after signal enhancement and compressional sonic logs after upscaling. Since the lack of structure permitted the assumption of a vertical axis of symmetry (VTI), we incorporate the following velocity matching formula (Hawkins et al, 2001)…”

Section: Velocity Model Buildingmentioning

confidence: 99%

“…The Dix inversion formula then transformed the stacking velocity into the reference 'sediment only' velocity perturbation AV(x,t). To reduce uncertainties of the reference isotropic model (Hawkins et al, 2001;Jones, 2003;Lambare et a l , 2007), we estimated the effective parameter 6 using eq. (1).…”

Section: Prestack Time Migration and Initial Velocity Estimatesmentioning

confidence: 99%

A study of sub-basalt depth imaging using the local Radon attributes on the Erlend Tertiary volcanic complex - North of Shetland, UK

Droujinine

Pajchel

Hitchen

2008

Netherlands Journal of Geosciences

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IAcquiring conventional 3 km towed streamer data along a 2D profile in the North of Shetland (UK) enables us to use the local Radon-attributes within the context of depth processing methodology for accurate delineation of volcanic units and imaging beneath high-velocity layers. The objective is to map the radially-dipping structure of the Erlend pluton and to investigate the potential existence of relatively soft Cretaceous sediments underneath volcanic units. Success in the Erlend Volcano study requires strict attention to the separation between different groups of events. The crucial point is the generalized discrete Radon transform formulated in terms of local wavefront (dip and curvature) characteristics. This transform is utilized during pre-CMP processing and migration to minimize event-coupling artefacts. These artefacts represent cross-talk energy between various wave modes and include the unwanted part of the wavefield. We show how to produce detailed subsurface images within the region of interest (exploration prospect only) by applying the closely tied processes of prestack event enhancement and separation, well-driven time processing for velocity model building, and final event-based prestack depth imaging. Results show enhanced structural detail and good continuity of principal volcanic units and deeper reflections, suggesting a faulted 0.6 -0.9 km thick layer of Cretaceous sediments in the proximity of well 209/09-1. Our interpretation complements existing low-resolution geophysical models inferred from gravity and wide-angle seismic data alone.

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Addressing anisotropy in 3-D prestack depth migration: A case study from the Southern North Sea

Cited by 13 publications

References 0 publications

P-Wave-Only Inversion of Challenging Walkaway VSP Data for Detailed Estimation of Local Anisotropy and Reservoir Parameters: A Case Study of Seismic Processing in Northern Poland

P-Wave-Only Inversion of Challenging Walkaway VSP Data for Detailed Estimation of Local Anisotropy and Reservoir Parameters: A Case Study of Seismic Processing in Northern Poland

3D Seismic Survey Design, Second edition

A study of sub-basalt depth imaging using the local Radon attributes on the Erlend Tertiary volcanic complex - North of Shetland, UK

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