Full waveform inversion: A North Sea OBC case study

Ratcliffe, Andrew; Win, Caroline; Vinje, Vetle; Conroy, Graham; Warner, Mike; Umpleby, A.; Štekl, I.; Nangoo, Tenice; Bertrand, A.

doi:10.1190/1.3627688

Cited by 33 publications

(18 citation statements)

References 4 publications

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“…Three-dimensional FWI has yielded impressive results on marine seismic datasets, producing high resolution velocity models which can be used directly for geological interpretation or for the migration of reflection seismic data to produce detailed images (e.g. Sirgue et al 2010;Ratcliffe et al 2011;Warner et al 2013;Mispel et al 2013;Jones et al 2013;Mothi et al 2013). The vast majority of such studies have utilised seismic data recorded on either hydrophone streamers or ocean bottom cables (OBC), in relatively shallow marine environments (water depth < 1,000 m).…”

Section: Introductionmentioning

confidence: 99%

Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Davy

Morgan

Minshull

et al. 2017

Geophysical Journal International

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SummaryContinental hyperextension during magma-poor rifting at the Deep Galicia Margin is characterised by a complex pattern of faulting, thin continental fault blocks, and the serpentinisation, with local exhumation, of mantle peridotites along the S-reflector, interpreted as a detachment surface. In order to understand fully the evolution of these features, it is important to image seismically the structure and to model the velocity structure to the greatest resolution possible. Travel-time tomography models have revealed the longwavelength velocity structure of this hyperextended domain, but are often insufficient to match accurately the short-wavelength structure observed in reflection seismic imaging. Here we demonstrate the application of two-dimensional (2D) time-domain acoustic full-waveform inversion to deep water seismic data collected at the Deep Galicia Margin, in order to attain a

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Section: Introductionmentioning

confidence: 99%

Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Davy

Morgan

Minshull

et al. 2017

Geophysical Journal International

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“…A combination of the velocity complexity of the gas and its absorption properties causes significant imaging challenges (Ratcliffe et al, 2011). It was discovered in 1977 in ~ 80 m of water, approximately 25 km southwest of Ekofisk field.…”

Section: Case-study Areamentioning

confidence: 99%

“…In our previous work here, the objective was to see the impact of FWI on the structural image (Ratcliffe et al, 2011;Warner et al, 2013;Ratcliffe et al, 2014). Achieving both goals should assist in interpretation of the area.…”

Section: Geophysical Challengesmentioning

confidence: 99%

Enhanced imaging with high-resolution full-waveform inversion and reverse time migration: A North Sea OBC case study

et al. 2014

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In a case study from the Tommeliten Alpha area of the Norwegian North Sea, imaging problems were caused by the presence of gas in the overburden. In particular, a large part of the reservoir is in a seismically obscured area (SOA) caused by the gas. Full-waveform inversion (FWI) and reverse time migration (RTM) dramatically improve the imaging from ocean-bottom cable (OBC) acquisition over the region. The FWI algorithm is pushed to 22 Hz to generate an extremely high-resolution velocity model, and RTM then becomes required to honor the complexity in the resultant velocity model. Consequently, migration is done with the FWI model to generate a highfrequency RTM image to 80 Hz. This image is approximately double the maximum frequency commonly used for RTM in the North Sea and matches that of equivalent Kirchhoff products, but with all the benefits in imaging that RTM brings, providing a subsequent impact on interpretation of the area. Figure 8. Comparison of 80-Hz VTI RTM sections zoomed to top-reservoir horizon depth for (a) line L1 migrated with the starting velocity model, (b) line L1 migrated with the FWI velocity model, (c) line L2 migrated with the starting velocity model, and (d) line L2 migrated with the FWI velocity model. Labels L1 and L2 refer to the yellow lines in Figure 4.

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“…Because of the combination of optimization algorithms and full wave equations, FWI can, in turn, offer more accurate velocity model with higher resolution than ray-based tomography and therefore dramatically improve pre-stack depth migration (PSDM) results (Ratcliffe et al, 2011;Silva et al, 2016). Since FWI recovers the physical parameters of the subsurface, for example, the P-wave velocity, the inversion result can be used to interpret the physical property of the by refracted waves.…”

Section: Introductionmentioning

confidence: 99%

Reflection full waveform inversion

Yao

2017

Sci. China Earth Sci.

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Because of the combination of optimization algorithms and full wave equations, full-waveform inversion (FWI) has become the frontier of the study of seismic exploration and is gradually becoming one of the essential tools for obtaining the Earth interior information. However, the application of conventional FWI to pure reflection data in the absence of a highly accurate starting velocity model is difficult. Compared to other types of seismic waves, reflections carry the information of the deep part of the subsurface. Reflection FWI, therefore, is able to improve the accuracy of imaging the Earth interior further. Here, we demonstrate a means of achieving this successfully by interleaving least-squares RTM with a version of reflection FWI in which the tomographic gradient that is required to update the background macro-model is separated from the reflectivity gradient using the Born approximation during forward modeling. This provides a good update to the macro-model. This approach is then followed by conventional FWI to obtain a final high-fidelity high-resolution result from a poor starting model using only reflection data. Further analysis reveals the high-resolution result is achieved due to a deconvolution imaging condition implicitly used by FWI.

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Full waveform inversion: A North Sea OBC case study

Cited by 33 publications

References 4 publications

Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion

Enhanced imaging with high-resolution full-waveform inversion and reverse time migration: A North Sea OBC case study

Reflection full waveform inversion

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