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In marine seismic surveys, seismic interference (SI) remains a considerable problem when marine seismic data sets are acquired in close vicinity of each other. We present a method for attenuating SI noise using a sparse Tau-P transform. Using a synthetic example, we demonstrate that this method effectively attenuates SI noise while preserving the seismic signals. Applying our method to real data confirmed our observations from the synthetic data example. Compared to the conventional Tau-P based method, our method leaves fewer residuals without observable damage to the primary signals.

The anelastic effects of the overburden cause seismic amplitude attenuation, wavelet phase distortion and seismic resolution reduction. It is desirable to correct the frequency dependent energy attenuation and phase distortion in a prestack depth migration. The situation becomes more challenging in complex geological regions with the presence of absorption, such as complex shallow gas clouds. The wavefields can be severely complicated and distorted by strong velocity contrast with the surroundings and serious attenuation, hence mask the image of the deep objectives. To deal with such challenges associated with absorption in complex geological regions which quite often needs to account for multi-pathing and anisotropy in wave propagation, we have developed a stable visco-acoustic TTI Reverse Time Migration based on our derived formulation for visco-acoustic wave propagation in TTI medium to compensate for the anelastic effects in the seismic data. We will demonstrate our visco-acoustic TTI Reverse Time Migration with both synthetic and field data examples.

We present a method for estimating the shape of salt bodies by using ray-based nonlinear slope tomography. The data to invert mainly consist of residual moveout (RMO) observed below salt shapes on migrated common image point gathers. We compute Fréchet derivatives made of traveltime derivatives with respect to depth Bsplines parameters describing salt bounding surface. Salt shape is progressively updated after each linearized tomographic step. We demonstrate the method on a 2D synthetic example and on a high-fold 3D land dataset from the Sultanate of Oman.

While most marine baseline surveys do not use broadband techniques, increasingly more monitor surveys are being adapted to broadband techniques that often use different receiver-depth profiles (e.g., deeper or variable-depth). A regular matching filter that has been commonly used in 4D time-lapse processing may be insufficient to normalize the wavelet difference between baseline data and monitor data because of the large difference in receiver-depth profiles. Deghosting can effectively remove the wavelet difference among vintages caused by different receiver depths. However, deghosting different vintages separately may cause inconsistent deghosting of common events and thus create false 4D signals. We propose a joint inversion scheme that uses both the baseline and monitor data (or more vintages) that deghosts common events consistently while preserving the difference among vintages. Using synthetic and field data, we demonstrate that joint deghosting baseline and monitor data provides a more accurate ghost removal and a more reliable 4D difference over separate deghosting of both data.

In the oil rich Bohai area, Ocean Bottom Cable (OBC) acquisition has become the new trend 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 azimuthal anisotropy can cause severe imaging challenges in the Wide Azimuth OBC data, particularly fault imaging which is sensitive to velocity accuracy. Fault imaging can be smeared and fault shadow can be observed within complex strike-slip fault system if the azimuthal dependency of wave propagation is not properly honored. In this paper, we will present a new orthorhombic model building flow and demonstrate with Luda OBC data that our approach can successfully reconcile the structural discrepancies between seismic images from different azimuths, thus provide a clear and sharp fault image with the WAZ stacking process.

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, full waveform inversion (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.

Receiver deghosting algorithms assuming a flat sea surface may be sub-optimal in the case of significant sea surface datum variations. We propose a method that begins by using the seismic data to calculate a sea surface profile. The sea surface profile is then provided to a modified linear Radon inversion scheme to model the receiver ghost. We compare receiver deghosting results using a flat sea surface datum and a variable sea surface datum on a marine dataset acquired in the North Sea. We show that receiver deghosting using a variable sea surface may improve wavefield separation; specifically, the clarity of the shallow reflectors is improved at the higher frequencies.

We introduce an inversion-driven free surface multiple modelling scheme based on multi-order Green’s functions. The approach optionally combines surface related multiple modelling with source designature and receiver deghosting. We demonstrate the effectiveness of the approach for peg-leg multiple suppression as well as highlighting the benefits of combined receiver deghosting and demultiple. In addition we show how the use of multiples can provide uplift for cable interpolation.

Ghost wavefield elimination is pivotal for improving the bandwidth and image resolution for marine seismic data. Synhronized multi-level source arrays, which aim to synchronize the primary wavefield and desynchronize the source ghost, can greatly attenuate the source ghost wavefield during acquistion. However, even with this advanced source design, some source deghosting is still needed and can be achieved using a 3D joint source inversion algorithm. We demonstrate that the joint source inversion method can properly and effectively eliminate residual source ghost in the synchronized multi-level source streamer data using both 2D synthetic data and 3D real data examples.