Method for bispectral picking of anelliptical NMO correction parameters
AssigneeCggveritas Services SA
InventorRisto Siliqi
Life of this patent
Estimating the term…
Abstract
Method of determining the velocity V and anellipticity η parameters for processing seismic traces in a common midpoint (CMP) gather comprising:—a preliminary step to define a plurality of nodes (dtn, τo), for each node (dtn, τo) defined in the preliminary step, the following steps:—for static NMO correction of traces in the CMP gather as a function of the values of the said parameters dtn and τo at the node considered, and calculation of the semblance function associated with the said NMO correction for the node considered; and—for each picked time to, a step including determination of the maximum semblance node (dtn (to), τo (to)),—and a final step to convert the dtn (to) and τo (to) parameters, so as to obtain the velocity to) and anellipticity η (to) laws.
Claims41
Method of determining the velocity v and anellipticity η parameters for processing seismic traces obtained from seismic receivers in a common midpoint (CMP) gather including an anelliptic (Normal Move Out) NMO correction, comprising:
- a preliminary step to define a plurality of nodes (dtn, τ0) in a CMP gather of a series of seismic traces, at least a portion of said traces corresponding to signals reflected by geological interfaces of a subsurface zone, said nodes being indicative of parameters dtn and τ0, wherein dtn represent the NMO correction for the maximum offset and τ0 represent the zero offset travel time in hyperbolic coordinates, said preliminary step being followed by
- for each node (dtn, τ0) defined in the preliminary step, the following steps:
- performing static NMO correction of traces in the CMP gather as a function of the values of the said parameters dtn, τ0 at the node considered, and
- calculating the semblance function associated with the said NMO correction for the node considered;
- and
- for each picked time t0, determining the maximum semblance node (dtn (t0), τ0 (t0)),
- a step to convert the dtn (t0) and τ0 (t0) parameters so as to obtain the velocity V (t0) and anellipticity η (t0) laws
- and a step of processing the seismic traces in view of the obtained velocity V (t0) and anellipticity η (t0) laws, the output of said processing used to represent the seismic traces in one or more images of at least a portion of the geological interfaces of said subsurface zone.
Dependencies are inferred from the claim text.