Cgg Services Sas

Cggveritas Services (u.s.) Inc.

Cggveritas Services S.a.

Benjamin Roure

Yves Lafet

Raphael Bornard

Laurene Michou

Jon Downton

Methods and apparatuses characterize fracture orientations in orthorhombic adjacent layer. Seismic data with azimuthal coverage enables calculating Fourier coefficients of reflectivity at an interface between the orthorhombic adjacent layers. The phases of 2and 4FCs may be used to infer the fracture orientations in the orthorhombic adjacent layers. Analysis of 2and 4Fourier coefficients' phases for different incidence angles may indicate that the fracture orientations in the orthorhombic adjacent layers are aligned, orthogonal, at 45&#xb0;, that one of the layers is isotropic, etc.

Characterizing fracture orientations in orthorhombic adjacent layers using the phase of azimuthal fourier coefficients

PP and PS seismic data are jointly inverted in a stratigraphic grid, using different time axes for PP and PS reflections. A ratio of PP and of PS waves'travel times inside a same layer cell maintained to be a function of a ratio of a P-wave propagation velocity and of an S-wave propagation velocity therein. Since PP and PS seismic amplitudes and travel times are due to elastic properties of the same structure, they can be inverted at the same time to provide better estimates of these elastic properties.

Joint inversion of compressional and shear seismic data in native time domains

Methods for seismic exploration of an underground formation including at least one anisotropic layer perform a joint velocity-variation-with-azimuth, VVAz, and amplitude-variation-with-azimuth, AVAz, inversion using the azimuthal angle stacks to obtain a structural representation of the underground formation. The structural representation is used to generate scenarios for exploiting resources in at least one layer of the underground formation.

Methods and systems performing joint VVAz and AVAz inversion

A method for evaluating anisotropy parameters using statistical moments calculates second and third central moments using reflectivity values associated with pairs of incidence and azimuth angles. The method further determines tangential and normal weaknesses for the location using the calculated second and third central moments for different incident angles. Linear and non-linear inversions of statistical moments are used to estimate the fracture weaknesses, anisotropic gradient (biased and unbiased), anellipticity variation and unambiguous orientation.

Method and apparatus for characterizing azimuthal anisotropy using statistical moments

Global inversion of multi-vintage seismic data uses simulated annealing to minimize a cost function simultaneously for all vintages and all angle stacks to yield values of geophysical properties. Each vintage is generated from an independent seismic survey of a subsurface structure conducted over a distinct period of time and includes seismic traces and angle stacks. An initial model of the subsurface structure is used and includes values for geophysical properties and time shift maps between vintages. The time shift map contains shifts in the seismic trace between vintages. The cost function includes a time shift map term for the difference between the time shift map and a calculated time shift of the seismic trace between vintages and is based on a proposed perturbation to at least one of the geophysical properties. The time shift map is also used as a global constraint on proposed perturbations of subsurface properties.

Time-lapse simultaneous inversion of amplitudes and time shifts constrained by pre-computed input maps

An improved method for analyzing seismic data to obtain elastic attributes is disclosed. In one embodiment, a reflectivity series is determined for at least one seismic trace of seismic data obtained for a subterranean formation, where the reflectivity series includes anisotropy properties of a formation. One or more synthetic seismic traces are obtained by convolving the reflectivity series with a source wavelet. The one or more synthetic seismic traces are inverted to obtain elastic parameters estimates. According to one aspect, the data inputs are angle-azimuth stacks. According to another aspect, the data inputs are azimuthal Fourier coefficients, u, v.

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Calgary, Canada

Benjamin Roure