Numerical analysis of far-field fault reactivation induced by reservoir cooling
Josselin Ouf (RWTH Aachen University, Geo-engineering)
Philip J. Vardon (Geo-engineering)
Kavan Khaledi (Fraunhofer Institute for Energy Infrastructures and Geothermal Systems, RWTH Aachen University)
W. Luo (RWTH Aachen University, Geo-engineering)
Mohammadreza Jalali (RWTH Aachen University)
Florian Amann (Fraunhofer Institute for Energy Infrastructures and Geothermal Systems, RWTH Aachen University)
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Abstract
This study presents a thermo-hydro-mechanical framework to model hydrothermal systems within a simplified faulted synthetic reservoir, replicating current production scenarios in The Netherlands and Germany. The reservoir, composed of porous and permeable sandstone, and the confining layer, made of porous but less permeable shale, undergoes a process where cold water is injected and hot water is extracted. A fault, situated 750 meters from the injection well, is investigated to examine the conditions when fault slip could occur. Various fault and formation stiffnesses are modeled to assess their impact on fault stability. Our analysis reveals that stress changes induced by hydrothermal operations can lead to fault reactivation, with the stiffness contrast between the reservoir and confining layers playing a significant role in when and where fault reactivation can occur. Stiffer confining layers lead to reactivation occurring more closely associated with the passage of the cooling front. In contrast, a stiffer reservoir results in greater and more gradual stress changes, making reactivation more closely related to the total volume of cooled rock.
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