Nonlinear Traveltime Optimization for Ray Tracing in Complex 3D Media

Abstract

A new method for solving the boundary value ray tracing problem in laterally variable media is presented. The strategy overcomes some well known difficulties that arise in standard shooting and bending methods. Problems related to: (1) the selection of new take-off angles, and (2.) local minima in multipathing cases, are overcome by using a stochastic optimization algorithm. At each iteration, the ray is propagated from the source by solving a standard initial value problem. The last portion of the raypath is then forced to pass through the receiver. The problem is put into a nonlinear optimization scheme in which total traveltime is globally minimized with respect to the initial conditions that produce the absolute minimum
path. A number of examples of multipathing in 2D and 3D media are examined.