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The carbonates in the pre-salt area of the Santos basin off-shore Brazil are good candidates for potential reservoirs of hydrocarbons. The presence of highly reflective stratified salt in this basin, combined with the focusing of energy due to the concave shape of these reflectors, causes relatively high amplitude inter-bed multiples to interfere with pre-salt reflectors. This multiple energy hampers the imaging and interpretation of these targets. We show that inter-bed multiple attenuation can be used to successfully remove the interference due to such multiples, thus improving the imaging of the pre-salt targets and facilitating improved interpretation. Using the water-bottom as the only inter-bed multiple-generating reflector turned out to be sufficient to attenuate most of the multiple energy. The attenuation of the multiples was done in the migrated domain.

While 5D data reconstruction has become widespread in recent years, we show that the use of 5D model spaces in some settings may result in sub-optimal handling of structures exhibiting HTI traveltime behaviour. To overcome these problems we propose the use of a 6D model space based on an extension of the parametric definition of Hugonnet et al. (2008). The model is solved using a sparse solver based on the anti-leakage Fourier transform of Xu et al. (2005). Synthetic and real datasets exhibiting HTI anisotropy are used to illustrate the signal preserving benefits of the approach.

While sufficient for many deep water datasets, vertical designature in shallow water environments can lead to unsatisfactory levels of ringing and amplitude striping, particularly on outer streamers where the assumption of a vertical farfield signature is least accurate. In this paper we modify the tau-px-py Radon equations to introduce a 3D directional designature algorithm. Assuming source-receiver propagation symmetry a 3D source re-signature operation is introduced and solved with an iteratively re-weighted least squares solver. The results of the strategy lead to improved spatial consistency and a reduction in the level of amplitude striping in the output data. Data examples from a real-world dual-level source project with variable depth streamer from the North Sea are given.

Receiver deghosting has been widely used to extend the bandwidth of marine seismic data. Efforts have also been made to remove the source ghost and signature to further maximize the bandwidth of the acquired seismic data. We present an inversion scheme for angle-dependent source deghosting and designature that honors modern complex air-gun array geometry. Using both a synthetic ocean bottom node dataset and a field streamer dataset acquired with a multi-level source, we demonstrate that our method effectively removes source ghost and signature either separately or jointly. The resulting images have a wider bandwidth.

We use a North Sea example to demonstrate that the use of geological constraints in this extended tomography allows improving the focusing of the seismic image and providing a more geologically plausible velocity model also below complex overburdens.

With the new broadband acquisitions, allowing to record frequencies down to 2,5 Hz, and the new tomographic tools, allowing to resolve for vertical velocity components up to 6 Hz, we have moved for velocity model building from the situation of a mid-frequency gap to the situation of an overlapping area in terms of resolution we can expect from tomography and migration-inversion. Full waveform inversion-guided migration velocity analysis has been proposed as an approach taking advantage of this new situation. We show here a first real data application of this innovative approach.

This case study highlights how the application of an optimized hydraulic fracture stimulation plan, by honoring lateral well geological heterogeneities measured by RoqSCAN, improved completion efficiency and well production within the Cleveland Sandstone formation, Oklahoma, USA.

In seismic land acquisition, harmonic–noise in vibrator ground-force has always been a major limitation in terms of data quality and productivity. In high productivity acquisition, vibrator distortion is usually prevented by waiting enough time between successive shots. Otherwise, it has to be reduced during seismic data processing. The low-dwell sweeps that are now currently used in production can induce even more important distortion issues. Harmonics from low frequency content can be considerably more spread out over time after correlation. Consequently, the extensive use of the low-frequency bandwidth for vibro-seismic sources prompted the need for improved distortion control, especially at low frequency. This paper describes a method to mitigate the harmonic distortion directly before emission. The output noise is measured and injected adaptively with opposite phase in the source input to converge towards an ideal output. The results show important noise reduction over the full bandwidth, with perfect low-frequency fidelity. A better source signal quality provides better seismic data that is easier to process, and opens new possibilities in terms of acquisition scenarios with possible productivity improvement.

The quality of the seismic data you record depends on the quality of the energy generated by the source, how it interacts with the subsurface and the ability to record all the effects of those interactions. To obtain the required response from the reservoir it is necessary to start with the right sound, at the right level, from the right angle. This requires the use of the right survey design, with the right equipment and the right acquisition methods, as well as preserving all the recorded information through advanced broadband processing and imaging. By integrating all the available geological knowledge with existing gravity and velocity information it is possible to design the optimum acquisition parameters for a survey. This integrated approach was used to design, acquire and process the new 25,000-km2 broadband multi-client 3D survey offshore Gabon, that covers the five blocks on offer in Gabon’s new deepwater license round.