Pressure Transient Testing Inversion for Fluid Flow Modeling in Fractured Rocks Using Simulated Annealing:-Three Dimensional Synthetic Cases

Abstract

The inversion of pressure transient tests by cluster variable aperture (CVA) simulated annealing is used as an inversion technique for developing models of fluid flow in fractured formations. A three-dimensional (3D) fracture network system is represented as a filled regular lattice of fracture elements. The algorithm iteratively changes element apertures for a cluster of fracture elements, which are chosen randomly from a list of discrete apertures, in order to improve the match to observed pressure transients. In this technique, the finite element code TRINET is used as a subroutine to solve for the pressure distribution at each iteration. Aperture size is chosen randomly from a list of discrete apertures. The cluster size is held constant throughout the iterations. This technique is applied to a 3D synthetic model to invert a series of three injection tests. The inversion result shows that the high transmissivity distribution is clearly reconstructed by CVA simulated annealing.