Method of processing data obtained from seismic prospecting

1. A method of processing data obtained from seismic prospecting of an earth formation, comprising the steps of:

obtaining data representing a multicomponent seismic signal from a multicomponent seismic receiver at a receiver location in an earth formation, in response to transmitting seismic waves into the earth formation;

performing a wave-equation migration of the multicomponent seismic signal to obtain a seismic image of the earth formation, wherein the polarization of the seismic wave at the receiver location is taken into account;

wherein:

the step of performing a wave-equation migration comprises:

a) obtaining a velocity model of the earth formation;

b) determining, using the velocity model, a wave field generated by a dipole source at the receiver location, for a plurality of orientations of the dipole source, to obtain a plurality of source field components;

c) determining, using the velocity model and the multicomponent seismic signal, a plurality of back-propagated wave field components;

d) obtaining the seismic image from the multicomponent source field and the plurality of back-propagated wave field components;

the source field components and the back-propagated wave field components each relate to a particular spatial dimension; and

the seismic image value at a point in the earth formation is calculated from a sum of products of the source field component for a particular source orientation and the complex conjugated back propagated wave field component for the corresponding spatial dimension, summed over a plurality of spatial dimensions.

2. The method according to claim 1 , wherein the seismic data include multicomponent seismic signals from a plurality of multicomponent seismic receivers, and wherein in the calculation of the seismic image value a summation over the receivers is carried out.

3. The method according to claim 1 , wherein in the calculation of the seismic image value an integration or summation over a plurality of seismic wave frequencies is carried out.

4. A method of processing data obtained from seismic prospecting of an earth formation, comprising the steps of:

obtaining data representing a multicomponent seismic signal from a multicomponent seismic receiver at a receiver location in an earth formation, in response to transmitting seismic waves into the earth formation;

performing a wave-equation migration of the multicomponent seismic signal to obtain a seismic image of the earth formation, wherein the polarization of the seismic wave at the receiver location is taken into account;

wherein:

the step of performing a wave-equation migration comprises:

a) obtaining a velocity model of the earth formation;

b) determining, using the velocity model, a wave field generated by a dipole source at the receiver location, for a plurality of orientations of the dipole source, to obtain a plurality of source field components;

c) determining, using the velocity model and the multicomponent seismic signal, a plurality of back-propagated wave field components;

d) obtaining the seismic image from the multicomponent source field and the plurality of back-propagated wave field components;

the source field components and the back-propagated wave field components each relate to particular spatial dimension; and

the seismic image value at a point in the earth formation is calculated from a sum of products of the source field component for a particular source orientation and the complex conjugated back propagated wave field component for the corresponding spatial dimension, summed over a plurality of spatial dimensions;

wherein the multidimensional source field and the multidimensional back-propagated wave field both have components in a plurality of spatial dimensions, and wherein a seismic noise image value at a point in the earth formation is calculated from a difference of products, wherein each product is calculated from a source field component and a different complex conjugated back propagated wave field component.

5. The method according to claim 4 , wherein the seismic data include multicomponent seismic signals from a plurality of multicomponent seismic receivers, and wherein in the calculation of the seismic image value a summation over the receivers is carried out.

6. The method according to claim 4 , wherein in the calculation of the seismic image value an integration or summation over a plurality of seismic wave frequencies is carried out.