Reservoir Focused Seismic Gather Conditioning

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Reservoir characterization workflows are much more sensitive to undesirable artifacts in the seismic data than those of structural interpretation. Issues with signal-to-noise ratio, offset dependent frequency loss, and event alignment on gathers must be addressed in order to optimally characterize rock properties and fluid fill in the reservoir.

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The optimum time to start thinking about seismic data requirements for reservoir characterization is in the acquisition design phase. We work with your team to model acquisition parameters that should produce proper fold and offset distribution required to calculate elastic rock properties at the reservoir level.

This collaborative approach is carried through to the seismic processing phase, where we iteratively apply processing parameters, testing for the best signal to noise ratio across the range of offsets at the reservoir level, and comparing the results with modeled seismic gathers at well locations. An optimal result is produced when the seismic data are rich in frequencies, relatively noise free, of consistent amplitude, and the signal events at the reservoir are aligned to the expected AVO modeled response at the reservoir.

Wide-azimuth acquisition introduces another conditioning requirement – velocity variation with angle and azimuth. CGG have developed new processing algorithms to analyze and remove these effects, providing measurements of the magnitude and direction of the anisotropy, which give an indication of the presence of fractures in the overlying strata.

Often times the seismic data at hand was not acquired and processed specifically for reservoir characterization. The seismic gathers resulting from PSTM or PSDM processing can be further high-graded to better address the additional challenges of advanced seismic techniques such as prestack inversion or azimuthal analysis. Evaluation of the seismic data for reservoir work entails multiple QC processes utilizing maps, petrophysical analysis, synthetics, anisotropic analyses and inversion techniques. The QCs are used to design a data preconditioning sequence which may include frequency and amplitude balancing, noise attenuation, anisotropic velocity analysis, and signal event alignment. This entire process is non-unique and, if necessary, iterative.

When properly evaluated and applied, the result is better quantitative reservoir characterization, improved interpretation and increased confidence.

Offshore - BroadSeis

BroadSeis

Broadest bandwidth, best low frequencies deliver accurate models for better decisions. Choose BroadSeis at all stages from exploration to production.

Onshore - UltraSeis

UltraSeis

Enabling quantitative interpretation for onshore reservoir development. Update your reservoir model from this fully integrated solution.

Subsurface Imaging - RTM Angle Gathers

RTM Angle Gathers

Retain the rich azimuth and reflection angle information carried in wide-azimuth data and bring the outstanding quality of RTM pre-stack.

GeoConsulting - Geophysical Services (SRC)

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