Industry Articles

In late 2009 CGG won a four-year contract with Pemex for a dedicated seismic vessel to acquire large, narrow-azimuth surveys in the deep offshore Mexican Gulf of Mexico. This contract was later extended to include two large 3D wide-azimuth projects. Under this contract, many records have been broken and milestones achieved, demonstrating Pemex?s commitment to the use of high-end technology to explore and develop Mexico?s natural resources as effectively as possible. Since the start of the original contract in 2009, new broadband technology has been developed and Pemex has embraced this technology by acquiring the world?s first-ever full-scale broadband, high-density, wide-azimuth survey specifically designed for field development.

We present a case study where a multitude of walkaway vertical seismic profiling (WVSP) data was employed in evaluating the accuracy of anisotropic velocity models used in a prestack depth migration (PSDM) project. We integrated the WVSP traveltimes with surface seismic PSDM residual moveout on migrated common-image gathers (CIG) in a joint inversion that determined the anisotropic model parameters. The resulting anisotropic model significantly reduces the mis-ties between the modeled and observed first arrivals in the various WVSP lines, in addition to the enhancement in CIG flatness and significant improvement in imaging.

As seismic processing technology advances, it opens opportunities for further improvements of existing datasets. This is especially important in the case of survey areas that may no longer be accessible for new seismic acquisition. The onshore Bahrain Field is just such a case because massive urban development since the original acquisition of a 3D seismic dataset in 1998?99 precludes any large-scale reshoot effort. The application of new 3D wide-azimuth processing techniques to the Bahrain dataset has substantially improved imaging of both shallow and deep reservoirs. Furthermore, the subset of the data volume that is near-surface/near-offset, and therefore wide-azimuth, has provided better fracture characterization of key shallow oil reservoirs. Here we describe the main processing steps that resulted in these image improvements, and weprovide an example of how the azimuthal data improved fracture characterization.

The ultimate goal of any seismic analysis is to extend reservoir knowledge beyond the wells. Neural networks represent a class of statistical methods that yield rich detail that can greatly assist in reservoir characterization and planning. While nothing is ever certain until a well is drilled and completed, the chances of success are noticeably improved with this approach.

This study used data from a three-month continuous reservoir monitoring experiment in Peace River, Alberta, Canada to measure spatial and temporal variations in nearsurface S-wave velocity (VS) and attenuation (QS) in the weathering layer. !e permanently buried sources generate a strong refracted S-wave that was recorded on buried 3C receivers. A method to perform receiver-side up-down separation and extract primary and ghost S-wavefields is presented.

In a recent interview with CGG, Oilfield Technology editor, Anna Scordos, asked Sophie Zurquiyah (Geology, Geophysics & Reservoir (GGR) division) how CGG intends to establish itself as an integrated geoscience company.

The Middle Magdalena Basin is an actively producing region in Colombia, which in recent years has been chosen for development by means of water and steam flooding. However, complex stratigraphy has challenged the development of a detailed reservoir static model. !e Tenerife 3C-3D experimental survey was conducted in 2009 as an integrated application (from acquisition design to interpretation) of multicomponent technology to differentiate lithology (sand and clay) in a Colombian field.

High-quality 3D data could provide new exploration opportunities in this highly prospective part of the Northern Carnarvon Basin, where underexplored areas exist within close proximity to producing fields.