Fracture Systems and Fluid Flow in Geothermal Reservoirs

Abstract

In most geothermal reservoirs fluid flow is largely controlled by the permeability of the fracture system in the host rock. Both for the direct use of reservoirs, as well as for effective stimulation, the geometry of the existing fracture system and its likely future development need to be known as accurately as possible. Here I review manifold elements of multidisciplinary approaches, altogether aiming at reliable estimations of potential fluid flow in geothermal reservoirs. Focus is on parameters and methods useful for fluid-flow estimations in geothermal reservoirs, and their interdependencies. Examples include the following: 1) Field studies in fracture-controlled paleo-geothermal reservoirs in fault zones in Great Britain and in outcrop analogues of Mesozoic rocks that could be used to host geothermal reservoirs in Germany. 2) Numerical models of local stress fields that provide the basis for numerical models of fracture propagation and fluid flow in geothermal reservoirs. The presented studies increase our understanding of fluid flow in geothermal reservoirs. Considering all relevant parameters and processes for reliable estimations of the existing fracture system and potential fluid flow in geothermal reservoirs contributes to maximize the likelihood of success of geothermal wells.