Industry Articles

Industry Articles Banner

The benefits of CGG technologies and services are regularly featured in the industry press. Find out more by consulting our e-library of published industry articles. Narrow your search by entering at least one search criterion:

 Search       Reset

Extracting seismic uncertainties from tomographic velocity inversion and their use in reservoir risk analysis

Leading Edge, February, 2017
Jeremie Messud | Mathieu Reinier | Herve Prigent | Patrice Guillaume | Thierry Coleou | Sylvain Masclet
©2017 SEG

Structural information in seismic images is critical for reservoir delineation, reserve estimation and well planning, but is also uncertain by nature. A cause for this is uncertainty in migration model estimated by tomography that straightforwardly affects position of migrated events, both laterally and vertically. We present a method that accounts for uncertainties in subsurface velocity model estimated by tomography, and translate them into the migrated domain. The method comes with QCs for validating computed attributes before integration with other downstream or interpretative information. The method is then applied to a North Sea area covered by multi-survey data.

 Download (PDF, 534.8KB)

Orthorhombic full-waveform inversion for imaging the Luda field using wide-azimuth ocean-bottom-cable data

Leading Edge, January, 2017
Yi Xie | Bin Zhou | Joe Zhou | Jiangtao Hu | Lei Xu | Xiaodong Wu | Nina Lin | Fong Cheen Loh | Lubo Liu | and Zhiliang Wang (CNOOC ltd-Tianjin)
©2017 SEG

Ocean Bottom Cable (OBC) acquisition has become the new trend in Bohai area with the benefit of operational flexibility, better illumination, better multiple elimination and better S/N for the targets at middle to deep depth. However, the presence of orthorhombic anisotropy causes severe challenges in imaging with Wide Azimuth (WAZ) OBC data, particularly fault imaging which is sensitive to velocity accuracy. Fault imaging can be smeared and fault shadows can be observed within complex strike-slip fault systems if the azimuthal dependency of wave propagation is not properly honored and velocity variation across faults is not properly modelled. To address these challenges encountered in imaging of Luda field with WAZ OBC data, we have developed a practical orthorhombic full-waveform inversion approach to invert for a high-resolution model in the presence of orthorhombic anisotropy. We will demonstrate that our orthorhombic FWI approach can produce high resolution velocity model which reconciles the structural discrepancies between seismic images from different azimuths, and significantly improves the focusing of the fault imaging and the imaging of structures beneath the faulting system. The combined effect of these improvements gives a clear uplift in the final seismic image.

 Download (PDF, 1.1MB)

Extracting geological information directly from high-resolution full-waveform inversion velocity models - a case study from offshore Trinidad

Leading Edge, January, 2017
Nick Benfield | Vishram Rambaran | Joel Dowlath | Tom Sinclair (BG-Group | a wholly owned subsidiary of Royal Dutch Shell plc) | Miles Evans | Jamie Richardson | Andrew Ratcliffe | and Andrew Irving (CGG)
©2017 SEG

This paper focusses on improving the seismic image on a dataset from offshore Trinidad & Tobago by using full-waveform inversion (FWI) to refine the shallow velocities and also describes geological information that can be inferred directly from the resulting velocity model. In the first half of the paper the geology of the region is introduced, then the imaging issues, before describing the FWI methodology and results. The second half of the paper discusses interpretational aspects of the FWI velocity model and highlights its use in a blind pore pressure prediction (PPP) test of well data.

 Download (PDF, 1.2MB)

A snapshot of geotectonics and petroleum geology of the Durban and Zululand Basins, offshore South Africa

First Break, December, 2016
Madhurima Bhattacharya | Gregor Duval
©2016 EAGE

This article reviews the status of hydrocarbon exploration and level of geological understanding in the Durban and Zululand Basins offshore South Africa and it provides clues and new ideas from seismic interpretation and observations of the latest CGG multi-client 2D shot in the area in 2014.

 Download (PDF, 1.6MB)

An offshore Gabon full-waveform inversion case study

Interpretation (SEG+AAPG), November, 2016
Bingmu Xiao | Nadezhda Kotova | Samuel Bretherton | Andrew Ratcliffe | Gregor Duval | Chris Page | Owen Pape
©2016 SEG

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.

 Download (PDF, 2.1MB)