Interval velocity and thickness estimate from wide-angle reflection data.

A method to estimate interval velocities and thickness in a horizontal isotropic layered medium from wide-angle reflection travel time curves is presented. The method is based on a relationship between the squared reflection travel time differences and the squared offset differences relative to two adjacent reflectors. The envelope of the squared-time-offset-difference curves, for rays with equal ray parameter, is a straight line, whose slope is the inverse of the square of the interval velocity and whose intercept is the square of the interval time. The method yields velocity and thickness estimates without any knowledge of the overlying stratification. It may be applicable to wide angle reflection data when either information for upper crust and/or refraction control on the velocity is not available. Application to synthetic and real data show that the method, used together with other methods, allows us to define a reliable 1D-starting model for estimating a depth profile using raytracing or another technique.