THREE-DIMENSIONAL MODELING OF SP DATA

Abstract

Since the SP method is sensitive to primary flows, such as heat flow or fluid flow, it has been used often to detect or monitor geothermal systems. Forward and inverse modeling, hopefully in three-dimensions, is important to fully assess the information content of these data. Three-dimensional (3D) forward modeling is a straightforward generalization of a technique advanced by Sill (1983) and illustrated by him for two-dimensional (2D) structures. The technique is illustrated using an analytic simulation of a convection cell.

The inverse problem is an instance of the source identification problem familiar from other fields such as cardiology. It reduces to a Fredholm Integral Equation of the First Kind, and as such is ill-posed and ill-condi-
tioned. Regularization of the equation using some means can give a source distribution, which must then be interpreted in terms of the primary flow parameters.

Interpretation of data gathened over the Newcastle geothermal system in terms of a radially symmetric fluid flow source distribution illustrates these concepts in a particularly nice manner.