Method for seismic processing, in particular for compensating birefringence on seismic traces
First Claim
1. A method of seismic processing for obtaining information on the geophysics of subsoil, the method comprising:
- acquiring seismic traces at at least one point on the surface of the subsoil, the seismic traces corresponding on each occasion to two perpendicular components of a shear wave emitted into the subsoil and reflected by different interfaces therein;
applying a succession of inverse transformations (⊥
) at least to a temporal portion of the seismic traces to obtain result traces, the inverse transformations to restore transformations that it is assumed that the shear wave has encountered on passing through a succession of layers in the subsoil, the layers being analyzed as a whole, and an operation of applying the succession of inverse transformations being repeated for different assumptions concerning birefringence in the layers;
for each of these assumptions, determining a value of a parameter representative of the coherence/similarity between the result traces; and
selecting as a function of the values obtained in this way that one of the assumptions which is considered as being most representative of the subsoil, two final result traces obtained for said assumption being compensated for the subsoil birefringency, wherein the two final result traces are obtained by analyzing the layers as a whole.
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Accused Products
Abstract
A method of seismic processing for obtaining information on the geophysics of the subsoil includes acquiring seismic traces at at least one point on the surface of the subsoil or in the subsoil, the seismic traces corresponding on each occasion to two perpendicular components of a shear wave emitted into the subsoil and reflected by different interfaces therein; applying a succession of transformations (⊥) at least to a temporal portion of the traces for each of these assumptions, determining the value of a parameter representative of the coherence/similarity between the result traces obtained in this way; and election as a function of the values obtained in this way that one of the hypotheses which is considered as being most representative of the subsoil, the two result traces obtained for said hypothesis being compensated traces of the subsoil birefringency.
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Citations
12 Claims
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1. A method of seismic processing for obtaining information on the geophysics of subsoil, the method comprising:
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acquiring seismic traces at at least one point on the surface of the subsoil, the seismic traces corresponding on each occasion to two perpendicular components of a shear wave emitted into the subsoil and reflected by different interfaces therein; applying a succession of inverse transformations (⊥
) at least to a temporal portion of the seismic traces to obtain result traces, the inverse transformations to restore transformations that it is assumed that the shear wave has encountered on passing through a succession of layers in the subsoil, the layers being analyzed as a whole, and an operation of applying the succession of inverse transformations being repeated for different assumptions concerning birefringence in the layers;for each of these assumptions, determining a value of a parameter representative of the coherence/similarity between the result traces; and selecting as a function of the values obtained in this way that one of the assumptions which is considered as being most representative of the subsoil, two final result traces obtained for said assumption being compensated for the subsoil birefringency, wherein the two final result traces are obtained by analyzing the layers as a whole. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A seismic processing method for revealing fractures in subsoil, comprising:
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acquiring seismic traces at at least one point on the surface of the subsoil, the seismic traces corresponding on each occasion to two perpendicular components of a shear wave emitted into the subsoil and reflected by different interfaces therein; applying a succession of inverse transformations (⊥
) at least to a temporal portion of the traces to obtain result traces, the inverse transformations to restore transformations that it is assumed that the shear wave has encountered on passing through a succession of layers in the subsoil, the layers being analyzed as a whole, and an operation of applying the succession of inverse transformations being repeated for different assumptions concerning birefringence in the layers;for each of these assumptions, determining a value of a parameter representative of the coherence/similarity between the result traces obtained; and selecting as a function of the values obtained in this way that one of the assumptions which is considered as being most representative of the subsoil, two final result traces obtained for said assumption being compensated for the subsoil birefringency, wherein the two final result traces are obtained by analyzing the layers as a whole.
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9. A method for obtaining information on the geophysics of subsoil, the method comprising:
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acquiring seismic traces at least one point on the surface of the subsoil, the seismic traces corresponding on each occasion to two perpendicular components of a shear wave emitted into the subsoil and reflected by different interfaces therein; applying a succession of inverse transformations (⊥
) at least to a temporal portion of the traces to obtain result traces, the inverse transformations to restore the transformations that it is assumed that the shear wave has encountered on passing through a succession of layers in the subsoil, the layers being analyzed as a whole, and an operation of applying the succession of inverse transformations being repeated for different assumptions concerning birefringence in the layers;for each of these assumptions, determining a value of a parameter representative of the coherence/similarity between the result traces.
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10. A method of seismic processing for obtaining information on the geophysics of subsoil, the method comprising
a) acquiring a pair of seismic traces at at least one point of the surface of the subsoil, said seismic traces corresponding to two perpendicular components of a shear wave emitted in the subsoil and reflected by different interfaces corresponding to a plurality of successive layers therein, b) choosing a first succession of sets of birefringence parameters which characterize a succession of birefringence transformations that it is assumed that the shear wave has encountered on passing through said plurality of successive layers, c) applying at least to a temporal portion of said two traces corresponding to two perpendicular components of the shear wave, a succession of transformations which are the inverses of said succession of birefringence transformations that it is assumed that the shear wave has encountered on passing through said plurality of successive layers, d) calculating on the pair of results traces thus obtained a cost function value which is based on the coherency/similarity of said results traces, e) repeating steps c) and d) for other succession of sets of birefringence parameters corresponding to other assumptions concerning birefringence of the plurality of successive layers, f) selecting, as a function of the cost function value calculated, the succession of sets of birefringence parameters which optimizes the coherency/similarity between the result traces obtained.
Specification