Inverse Modeling of Fractured Geothermal Reservoirs Using Pressure Interference Data

Abstract

Numerically inverting simultaneous pressureinterference
measurements from multiple observation
wells can help to establish the large-scale spatial
distributions of permeability and storage within a
geothermal reservoir. For realistic results, it is
important to incorporate double-porosity (MINC)
descriptions into the modeling process to properly
reproduce the short-term pressure-transient response
to production or injection. A new finite-difference
inversion program has been developed for this
purpose. The reservoir is represented as a threedimensional
network of grid blocks, and the
description is restricted to single-phase (liquid) flow.
The single-phase limitation permits the linearization
of the pressure-diffusion equation in the sub-grid
ìmatrix regionî, so that MINC descriptions may be
accommodated at little additional computing cost.
The ìsimulated annealingî method is used as the
optimizing technique.