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We show how the method recently proposed in Messud et al. (2017; 2017b) allows to consider “resolved space” tomographic uncertainties in complement to total tomographic uncertainties. Resolved space uncertainties are obtained by restricting the tomography model space to the one that can be resolved by tomography. Total uncertainties mostly quantify the illumination uncertainties, whereas resolved space uncertainties tend to be more correlated to the final tomography model. We illustrate how those two uncertainties give complementary information for the subsequent seismic interpretation.

This work highlights visco-acoustic full-waveform inversion (Q-FWI) as a method for estimating high-resolution velocity and attenuation models. We present a very large, real data, case study where Q-FWI has been applied to ~36,000 km2 of 3D, narrow azimuth, variable-depth streamer data over the North Viking Graben region of the northern North Sea. The results show that Q-FWI can invert for both velocity and attenuation with a high degree of spatial and vertical resolution. Our visco-acoustic FWI results, in comparison to those from conventional acoustic FWI, are supported by superior imaging in an attenuation compensating pre-stack depth migration.

Land surface seismic data are usually strongly affected by the presence of surface waves, (ground-roll), which can completely obscure the underlying primary reflection signal. It is therefore crucial to isolate the reflection signal for both imaging and amplitude analysis needs. Complex near-surface conditions complicate the ground-roll attenuation and may introduce other sources of noise such as multiples. We present an application of interferometric ground-roll removal and 3D convolutional de-multiple method on a seismic dataset acquired onshore North Kenya, where the shallow subsurface was characterized by strong heterogeneity and structural complexity.

Hydrocarbon prospection with seismic data on Barents Sea can be difficult to interpret because of severe contaminations of the sections by diffracted multiples residual noises often located above the objectives. Those diffracted multiples mainly result from significant scars of the sea floor produced by paleo-iceberg drifts during glacial ages. To mitigate this problem, a new marine seismic design has been developed which consist into a split-spread geometry where three different shot locations are located on the middle of the spread while acquiring broadband seismic signals. It allows for improved subsurface illuminations allowing for sharp and detailed representation of ground reflectors, including the sea floor. We used several multiples models in simultaneous adaption procedures, including 3D SRME models, but also 3D wave-equation based multiple modeling to fully benefit from those available rich subsurface reflectivity representations. On top of that, an innovative and specific implementation of WE modelling allowed for building diffracted multiples “only” models, into separated datasets for feeding the multi-model adaptive subtractions while preserving primary information (specially low frequencies) with AVO-driven primary models. The ensemble lead to unseen and improved demultiple results on those difficult areas.

This paper is the second part of two papers presenting the new source-over-cable marine acquisition solution. It presents the actual large-scale ~1950 km2 marine seismic acquisition as well as discusses the novel processing and imaging involved with this unique split-spread towed marine data. The acquisition setup consisted of a streamer vessel towing 14 streamers trailed by a shooting vessel in the middle of the streamer spread allowing for both positive-, zero- and negative-offsets to be recorded. Fast track migrations along with early QC and initial demultiple results from the new source-over-cable acquisition data, indicates that the new data delivers on its promises of superior image quality. The benefits are drawn from a multitude of new aspects such as but not limited to split-spread source-over-cable acquisition, dense streamer spacing and deep towed zero- and near-offset recording of energy from the new triple wide-tow-sources with very dense shot point interval using dithered overlapping shots.

This paper reviews the benefits of using “high-end new-generation” de-noising tools on a broadband single-source single-sensor Wide Azimuth survey acquired in Kuwait. A processing pilot has been conducted in a very challenging area containing agricultural and industrial zones, as well as various natural and man-made obstructions, leading to large holes and irregularities in the acquisition. We show that the in-place solution is correctly recovering the emitted broadband signal, by doing a dedicated processing on highly noise contaminated elementary traces. Then, once properly de-noised, a 5D interpolation process can faithfully reconstruct a consistent high resolution image, from the shallow to the deeper part. Appropriate de-noising steps prior to the 5D interpolation is also crucial for further processing steps as demultiple, pre-stack time and depth imaging and reservoir characterization.

Internal multiples constitute a major challenge for imaging. Artefacts generated by incorrectly imaging internal multiples interfere with targets, affecting the interpretation and contaminating amplitude analyses in the reservoir. The Santos basin is a particularly challenging example of this problem because of the presence of stratified salt. We implemented a method recently proposed by Van der Neut and Wapenaar (2016) to attenuate internal multiples and successfully applied it to a data set from the Santos basin.

While full wave based velocity model building approaches have earned their stripes during the last decade, ray based approaches remain the working horse in industry. I review here first the successes and the limitations of both families of approaches. If it appears that ray based approaches suffer of limitations in complex media, others of their characteristics like the picking (often seen as a weakness) or the computation of Fréchet derivatives may also appear in practice as decisive advantages. I believe that these are points on which we should challenge and even inspire full wave approaches. By the end rather than opposing ray based and full wave approaches I review the various trends in terms of the combination of the tools and concepts which appear from my point of view as the most promising.

Deriving high-resolution velocity models in heavily faulted areas is challenging. This is further complicated by the presence of gas bodies at multiple depth levels. In case of a WAZ or FAZ dataset, azimuthal anisotropy effect can be significant, depending on the presence of a principal stress orientation. To address these challenges, orthorhombic full waveform inversion (Ort-FWI) approach has been used to recover a high-resolution velocity model, addressing lateral velocity variations across faults or due to gas bodies, while honoring the azimuthal velocity variations. We show how Ort-FWI produces a high-resolution velocity model that improves fault focusing and heals fault and gas shadow effects.