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DENVER–The economics of unconventional plays can be improved by placing horizontal wellbores to target facies with the most favorable reservoir and geomechanical properties. Recognizing that, an integrated multidisciplinary approach was developed to reduce economic risk, facilitate improved and faster decision making, and enable more efficient and effective well placement in a tight, stratigraphically complex Upper Cretaceous Sandstone in the Powder River Basin. The subsurface environment was known to exhibit significant variations in lithofacies and reservoir properties, both laterally and vertically. The objective was to provide an accurate and synergized understanding of interwell reservoir characteristics, quantitatively honoring all input geoscience data and verifying through blind well testing. That goal was achieved by utilizing geostatistical inversion to predict lithofacies and reservoir rock/geomechanical properties that honored data from multiple disciplines.

An integrated geological and petrophysical workflow was used to evaluate the Jurassic shale plays in southern England. It illustrates how sedimentological and electrofacies interpretations were integrated with QEMSCAN data to significantly improve petrophysical interpretations and TOC estimates from logs using the CARBOLOG method. Reservoir quality risk maps were based on the sedimentological facies and log-derived elastic properties. Additionally, source quality and maturity were combined to create generation risk maps. The risk for ground water contamination was evaluated and was combined with the reservoir and generation risk maps to create common risk segment maps and identify the "sweet spots".

A quantitative interpretation was carried out in order to improve geological model and de-risk the prospect in the next exploration drilling campaign. Recently drilled exploration wells based on conventional seismic interpretation drilled through channel levee instead of the targeted channel core. Vertical resolution, reservoir quality, distribution and continuity of the channel feature are the main risks. A geostatistical inversion guided by rock physics modeling and deterministic inversion has been conducted to improve resolution, analyze the rock character and deliver probabilistic reservoir properties analysis as part of risk assessment. The results show that this technique improves the mapping of channel features associated with porosity and volume of clay distribution in comparison to the deterministic inversion or conventional seismic interpretation.

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.

The deepwater Gabon South Salt basin represents one of the last underexplored regions of the West African continental margin. A new 25,000-sq km (9,653-sq mi) broadband 3D seismic survey was recently acquired in the basin as part of an integrated eoscience program to support the Gabonese Republic’s new deepwater 11th Licensing Round. Given the high-quality results seen so far, final results are expected to be a significant resource for explorationists to de-risk this promising exploration arena.

Removing the band limitation by the seismic source wavelet may further enhance the spatial resolution of seismic images after de-ghosting and amplitude attenuation compensation. In this abstract authors propose a new de-signature method that incorporates structural conformity constraint and sparse regularization into the inversion-based deconvolution to achieve better signal-to-noise ratio and geological coherence in the resolution-enhanced output images. The new method was applied to field data; and compared with an inversion-based method without sparse regularization and structural conformity constraint, the new method gives cleaner and more coherent seismic images meanwhile with broader bandwidth. Acoustic impedance inversion was carried out after de-signature, and a more detailed and coherent impedance volume was obtained.

While for reverse time migration deconvolution imaging condition offers the strongest possibility for source designature and compensation of illumination, cross-correlation-based imaging conditions are the most widely used due to their high stability. We propose here a general theoretical frame and practical solution for stabilizing deconvolution-based reverse time migration. Our approach involves an optimization scheme regularized by a set of constraints. The proposed constraints insure both high-resolution and removal of low frequency migration noise arising in case of diving or reflected waves in the background model. We show the improvement obtained with our approach on synthetic and real datasets.

Porosity estimation using EMERGE for an onshore Abu Dhabi field. CGG processed the seismic and it was followed by seismic inversion. The P-impedance was further used in predicting the porosity. This porosity result very helpful to client to well planning and drilling to target the best porosity in the reservoir. Porosity result matched very well with the new well's acquired porosity data.

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.