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We present a FWI case study from offshore Gabon of an extremely large dataset covering an area ~25,000 km2, demonstrating that FWI can be applied to this size of survey in a timely manner. The history of the South Gabon basin is complex, leading to a rich geological picture today and challenging velocity model-building process. FWI is able to help with this process and the resulting velocity model reveals features that improve the migrated image. In addition, the detail in the FWI velocity model is shown to aid the geological interpretation by highlighting, amongst other things, the location of shallow gas pockets, buried channels and carbonate rafts.

The success of any broadband survey is dependent upon the accuracy with which acquisition and environmental factors are compensated for in processing. Such compensation ideally involves directional source designature and deghosting along with receiver deghosting. Traditionally, receiver deghosting is applied in the shot domain, and directional designature in the receiver domain. We introduce a robust algorithm working in the joint shot-receiver domain that simultaneously corrects for source and receiver side effects in a single process. The algorithm is shown to produce broadband results with improved spatial consistency compared with sequential directional designature followed by receiver deghosting on a North Sea dataset.

Abstract focusses on the LiveLand ESA IAP project and summarises how earth observation, weather forecast and GNSS can assist with the challenges transport operators across Scotland experience in relation to landslides and ground deformation along transport routes.

3D seismic data is only geophysical data which has good lateral sampling. Therefore, the use of seismic data to predict elastic properties away from a well is a widely used process. However transforming these elastic properties into geomechanical and other reservoir properties requires integration of different data sets (e.g. wireline logs, core and cuttings) at various scales. The integration of all data sets is essential for de-risking seismic amplitude supported interpretations. This study demonstrates how this approach and methodology was used to help predict important engineering properties in 3D space and away from any well control. The final inverted volumes were used to pick minimum intermediate casing points and, to predict maximum and minimum mud-weights both of which provide significant capital savings in casing design and/or lost bottom hole assemblies.

In this paper we present a practical extension of earlier work on the estimation of anisotropy parameters from isotropic techniques. We will take a closer look at the implications of working with effective elastic parameters in anisotropic (TI) seismic reflection inversion. In particular, for HTI media, the magnitude of the azimuthal Fourier terms is assessed. For many natural rocks the harmonic equations describing effective HTI anisotropy can be simplified, allowing for faster and more cost effective estimation of the magnitude and orientation of the anisotropy. Limits to these approximations in terms of the number of input azimuthal sectors used in the estimations are discussed.

We use the concepts of entropy and information theory to design a confidence measure for Bayesian facies estimations. Bayesian analyses provide the probabilities of occurrence of each constituent facies in a set. The entropy analysis uses all of these to establish a Confidence Index describing the reliability that the most-probable facies is in fact a clear best choice. We apply these ideas to various facies estimates from Gulf of Mexico inversions.

We address the problem of creating low frequency models for AVO inversions, investigating two workflows, neither of which involve well log interpolation. The first workflow creates a constant but structurally-compliant low frequncy model from averages over available logs. Facies analysis is done from the inversion outcomes. The second workflow takes the facies from the first workflow and together with per-facies trends creates a new model for a second pass of inversion. The results of the subsequent facies analysis are compared with the first in several ways and found to be superior. Notable in the analysis is the inclusions of several types of uncertainty which becomes useful in assessing risk.

CGG, together with TGS, recently acquired a multi-client TopSeis™ 3D seismic survey in the Barents Sea. The survey, known as “Greater Castberg” was acquired and imaged using the latest advances from CGG's proprietary TopSeis solution. The latest advances include a wide distribution of five sources over the spread together with one source in front of the spread. An early fast-track dataset shows outstanding imaging of the Greater Castberg area’s highly diverse and complex geology. An advanced fast-track volume will be ready for licensing in May and the final dataset will be available in Q1 2021.

We discuss the advantages of multidimensional (in data space) optimal transport (OT) full waveform inversion (FWI). We show that a careful formulation results into an enhanced coherency of the events continuity in the move-out direction, that leads to an improved velocity update compared to least squares but also to monodimensional (in data space) OT FWI. This is illustrated on both marine and land field datasets.