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

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.