Multi-Shot Processing For Better Velocity Determination

Abstract

We develop a linear programming inversion scheme to estimate lithology from well log data. The inversion described severely limits the dependence on core retrieval, and makes accurate mapping of new parameters possible. There are no limitations on the number of input well logs or output lithologic fractions. Because the method uses an L-I norm error measure, it should be more ·robust than otherwise similar techniques. Other advantages of the technique include the straightforward imposition of inequality constraints, and strictly positive volume fraction results. As specific examples we apply the method in a variety of geologic situations, and compare our results to those achieved via coring. We also test the new method against conventional least squares inversion algorithms. While both methods perform well, the linear programming inversion yields improved results when formation petrophysical properties are not known accurately.