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Changes in fracture direction across interfaces can have an important impact on PS-wave reflection coefficients in azimuthally anisotropic media. Extending conventional joint inversion with P-waves to include amplitude variations with azimuth (AVAz) would use radial and transverse reflection coefficients (RPSV and RPSH, respectively), and present a number of challenges. One of these is that layerstripping (LS) must be done either prior to or during joint inversion with fast PS1- and slow PS2-waves for azimuthal rock properties (e.g., fractures or stress directions). Also, null amplitude directions of RPSH can be shifted in azimuth when fracture direction changes across the interface, and will be different from the actual fracture direction. Thus, a full waveform inversion (FWI) approach with-out registering PS-waves to P-wave time could be more practical than attempting to align them prior to joint AVAz inversion.

We presented a joint tomography flow for OBN and streamer WAZ data in deep water Gulf of Mexico. This tomography provides the method to utilize surface offset gathers from surveys with different shot and receiver datums together for joint tomography. By incorporating both OBN and streamer data in tomography, the aperture and coarse sampling limitations of OBN can be overcome, and the full azimuth coverage, better low frequency, longer offsets, and higher S/N of OBN data can benefit tomography. Subsequently we are able to build a better velocity model.

We discuss methods to quantify the impact, reliability and value of low frequencies as provided in modern towed streamer broadband acquisitions. Acquisition, processing and inversion all have a role to play in creating reliable low frequency data. In this paper, focusing on marine data, we discuss various aspects of low frequency technology, associated uncertainties and QC methods. We address two key questions: Can broadband deliver the low frequencies? What value do they have? We show that scanning for the crossover frequency at well locations, where the background model is optimally known, is a useful way to visualize the impact of, and quantify the value of the low frequencies. Uncertainties due to unknowns such as wavelet errors at low frequencies and optimal regularization parameters such as sparseness constraints are discussed. Using this method, with a North Sea 3D multi-client data example, we show that broadband data provides valuable information, compared to conventional data that has been broadband processed.

Thrust complex imaging in the Timor Trough suffers from the fault shadows due to strong lateral velocity variation. We demonstrate a new workflow to tackle this. Broadband seismic data were acquired with high signal-to-noise ratio of low frequency. With broadband input, FWI derived better velocity model at the shallow water thrust area where the reflection tomography has limitation. Compared to conventional tomography which has difficulty in addressing the sharp velocity boundary properly, fault constrained tomography (FCT) uses the interpreted fault planes as constraint for inversion and benefits from better low frequency penetration in the severe fault shadows. Broadband seismic and depth imaging with FWI and FCT make a step change over the thrust complex areas.

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.