NUPUS - Teilprojekt "A volume-based conceptual approach for the analysis of hydraulic and geomechanical processes causing fault reactivation"

Several technologies linked with underground resources such as geothermal power generation, disposal of waste water, CO2 storage, enhanced oil recovery or hydraulic fracturing involve the injection of fluids into the subsurface. This corresponds with changed hydraulic and mechanical conditions of the reservoir and could possibly lead to the reactivation of pre-existing faults. Such a slip event on a fault and its implications for the flow field may sometimes be a desired result to enhance the productivity of the reservoir exploitation, but can become crucial for the public perception of a project, too. This highlights the necessity to increase the knowledge base of coupled hydraulic and geomechanical modelling to better understand the relevant processes.

Previous work has already introduced elastic deformation of the rock matrix to the open source simulator for flow and transport processes DuMuX (www.dumux.org). This allows to take geomechanical effects such as surface uplift, changed effective porosity and permeability into account. In addition, an evaluation of the failure criterion was implemented and regions prone to failure could be identified.

The aim of this project is to extend the modelling capabilities towards the simulation of fault reactivation resulting from fluid injections. In this context, we work along the hypothesis that this goal can be achieved by using a volume-based approach, which does not require to model the fault as a discrete surface but as elements representing a fault zone instead. Our first efforts are directed towards modelling shear failure on the fault plane and the effects of a slip event on the flow field, but further research will also focus on tensile failure and the opening of pre-existing fractures.

Class, Holger

Beck, Martin

LH2

02/2013 - 12/2015

DFG (Internationales Graduiertenkolleg NUPUS)