Abstract
The installed capacity of geothermal systems for direct use of heat is increasing worldwide. As their number and density is increasing, the their interaction with subsurface faults becomes more important as they could lead to safety risks from induced seismicity. Assessment and management of such risks is essential for the further development and extension of geothermal energy for heating. At the same time, the economic output of geothermal systems can be marginal and is hence often supported by subsidy schemes. A combined assessment of fault stability and economic output could help operators to balance economic and safety aspects, but this is currently not common practice. In this study we present a methodology to assess field development plans based on fault stability and Net Present Value (NPV) using reservoir simulations of a fluvial, heterogeneous sandstone representative of the majority of direct-use Dutch geothermal systems. We find that the highest friction coefficient leading to exceedance of the Mohr–Coulomb failure criteria in this sandstone is 0.17; such values could be encountered in clay-rich fault gouges. Similar or lower fault permeability compared to the reservoir results in no changes and an increase respectively of both NPV and fault stability with larger Fault-to-Well Distance (FWD). Fault permeability higher than the reservoir permeability results in a minor increase in NPV with smaller FWD. Our results demonstrate that a combined analysis of thermal, hydraulic, mechanical and economic assessment supports a responsible and viable development of geothermal resources at a large scale. The importance of a high spatial density of supporting stress data will be essential for a better understanding and quantification of economic and fault stability effects of geothermal operations.
Highlights
Installed capacity and generated energy of geothermal systems for direct-use of heat is on the rise (Lund and Toth 2020) as they form a promising energy source that can deliver renewable, low-carbon, baseload energy for industrial and domestic usage
The present analysis is based on three discrete parts: reservoir simulations using the Delft Advanced Research Terra Simulator (DARTS), economic simulations using an economic model and fault-stability analysis with a model based on the Coulomb failure criterion
This section concludes with the combined results of the Net Present Value (NPV) and the fault stability
Summary
Installed capacity and generated energy of geothermal systems for direct-use of heat is on the rise (Lund and Toth 2020) as they form a promising energy source that can deliver renewable, low-carbon, baseload energy for industrial and domestic usage. The proper assessment, evaluation and mitigation of safety risks is essential for local communities and the environment. One of these risks is that geothermal operations induce seismic events. The required acceleration and expansion of geothermal operations depend on the assessment and management of their potential safety risks (Buijze et al 2019b; Knoblauch et al 2019). This is essential for social acceptance of the increased use of geothermal energy
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
