Method for processing reflection seismic traces recorded for variable offsets

Method of processing reflection seismic traces recorded as a function of time (t) for offsets (x) variable between a minimum offset and a maximum offset, wherein:

• gathers d(t,x) of normal moveout corrected (NMO corrected) common midpoint seismic traces are constituted in a first domain (t,x) from recorded seismic traces and a time dependent correction velocity law (V.sub.NMO),
• a transform is applied to the d(t,x) gathers in said first domain so that there corresponds to each d(t,x) gather a .mu.(.tau.,q) diagram in a second domain .mu.(.tau.,q), so that a seismic event distributed along a curvilinear trajectory in the d(t,x) gather is focused in an energy concentration area in the .mu.(.tau.,q) diagram in the second domain, the variation (.tau.) designating the propagation time of the seismic waves with reflection for a null offset (x=0) and the variable q being a parameter associated with the curvature of said curvilinear trajectory, characterised in that, in each .mu.(.tau.,q) diagram:
• a) the coordinates (.tau..sub.k,q.sub.k) of an apparent centre of each energy concentration area are picked,
• b) a window containing all of said energy concentration area is determined for each energy concentration area,
• c) each energy concentration area is swept in the corresponding window centred at the point with coordinates (.tau..sub.k,q.sub.k) by a straight line segment that pivots successively about each of the points with coordinates (.tau.,q.sub.k) inside said window and the slope of which is equal to the square of the offset and varies between two limits bracketed by the squares of the minimum and maximum offsets,
• d) the amplitudes of the signals in said window and intercepted by said straight line segment are stacked along said straight line segment, and in that:
• e) the stacked values for each energy concentration area are represented in the form of a D(.tau.,x.sup.2) diagram in a third domain (.tau.,x.sup.2).