Computerized method of characterizing a geological region of interest and computer program implementing this method
A data set comprises data obtained by seismic imaging of a region of interest during an observation period. An intrinsic geological variability of a region is determined from the comparison of reception signals for neighbor bins as a function of a difference in signal geometry for the neighbor bins.
1. A computerized method of characterizing a geological region of interest comprising:
providing a data set comprising data obtained by seismic imaging of the region of interest during an observation period, said data set comprising, for each bin of the region of interest, data related to an emission signal, a reception signal, and a signal geometry,
repeatedly, for all bins of a region of interest, a processor determines an intrinsic geological variability of a bin of the region of interest from the comparison of reception signals for neighbour bins as a function of a difference in signal geometry for said neighbour bins, thereby obtaining a map of the intrinsic geological variability of the region of interest, and
displaying said map on a display.
2. The method according to claim 1 , wherein signal geometry comprises data related to location of emission of the emission signal, location of reception of the reception signal, and estimated location of reflection by earth of the emission signal.
3. The method according to claim 1 wherein said processor determines said intrinsic geological variability of a bin of the region of interest by estimating said intrinsic geological variability as a distance equal to the difference in geometry for which a difference in reception signals between bins is over a predetermined threshold.
4. The method according to claim 1 , wherein comparison of two reception signals involves the signal-to-distortion ratio of a first of the two reception signals with respect to the second of the two reception signals.
5. The method according to claim 4 , wherein the signal-to-distortion ratio is defined as ∥b∥ 2 /∥d∥ 2 , when m is written as m=δ r *b+d, where b is the first reception signal, m the second reception signal, and δ r is a factor representative of geometrical timeshifts of the first and second reception signals with respect to one another, and d is a random geological distortion term.
6. The method according to claim 5 , wherein the signal to distortion ratio is estimated as max(x bm ) 2 /(1−max(x bm ) 2 ),
where x bm designates the normalized cross-correlation function between the base and the monitor and max designates the maximum of a function.
7. The method according to claim 4 , wherein the signal to distortion ratio is estimated from the random variable ΔGDP representing the distance between reflection points of the two reception signals in the bin.
8. A method of characterizing a geological region of interest comprising generating a data set by seismic imaging and applying the method of claim 1 to said data set.
9. A method of setting-up a seismic imaging acquisition comprising:
performing a method according to claim 1 , and
determining parameters of said seismic imaging acquisition from a result of determining said variability.