TARGETING LOCALISED UPWELLINGS WITH A NEW MULTIPHYSICS SIMULATOR

Abstract

A paradigm shift in geothermal engineering is to target specifically fault zones of high permeability and potential convection. By embracing the concept of convection as an efficient mode of heat transfer, the drilling costs may be reduced significantly as localised upwellings can be targeted. The problem remains to identify the location and depths of these potential upwellings from geophysical and geological data.
We present a new multiphysics simulator where the occurrence of convection can be made using a fundamental stability analysis known as the pseudo-arclength continuation method. We find that localised convection can be triggered by a local additional heat source in active faults (known as frictional or shear heating). Another finding is that deep advective topography-driven sweeps can be pinned on suitably located fault zones. With these additions, we can better numerically simulate convection in fault zones with more realistic parameters such as lower permeabilities and narrower fault damage zones. These findings can be significant in case studies in major geothermal sites. We present a preliminary analysis from two extension zones: 1) the Perth Basin half-graben setting in Western Australia, and 2) the Rhine Graben setting (Soultz-sous-Forêts, Landau).