Enhanced Geothermal Systems: Mitigating Risk in Urban Areas

Kraft, Toni; Martin, Paul Marius; Wiemer, Stefan; Deichmann, Nicholas; Ripperger, J.; Kästli, Philipp; Bachmann, C. E.; Fäh, Donat; Wössner, Jochen; Giardini, Domenico

doi:10.1029/2009eo320001

Cited by 69 publications

(38 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Geothermal sites in the Rhine Graben near Basel , Landau (Grünthal, 2014) and Soultz-sousForêts (Dorbath et al, 2009), however, have experienced 2.5 events due to EGS activities (Table 1). Although this seismicity has been short lived it has attracted public concern due to its proximity to populated areas (Kraft et al, 2009). At other sites, geothermal seismicity is entirely of low magnitudes and then may drop below the detection threshold, possibly due to geologic conditions, e.g.…”

Section: Introductionmentioning

confidence: 99%

Analysis of induced seismicity in geothermal reservoirs – An overview

et al. 2014

Self Cite

View full text Add to dashboard Cite

In this overview we report results of analysing induced seismicity in geothermal reservoirs in various tectonic settings within the framework of the European Geothermal Engineering Integrating Mitigation of Induced Seismicity in Reservoirs (GEISER) project. In the reconnaissance phase of a field, the subsurface fault mapping, in situ stress and the seismic network are of primary interest in order to help assess the geothermal resource. The hypocentres of the observed seismic events (seismic cloud) are dependent on the design of the installed network, the used velocity model and the applied location technique. During the stimulation phase, the attention is turned to reservoir hydraulics (e.g., fluid pressure, injection volume) and its relation to larger magnitude seismic events, their source characteristics and occurrence in space and time. A change in isotropic components of the full waveform moment tensor is observed for events close to the injection well (tensile character) as compared to events further away from the injection well (shear character). Tensile events coincide with high Gutenberg-Richter -values and low Brune stress drop values. The stress regime in the reservoir controls the direction of the fracture growth at depth, as indicated by the extent of the seismic cloud detected. Stress magnitudes are important in multiple stimulation of wells, where little or no seismicity is observed until the previous maximum stress level is exceeded (Kaiser Effect). Prior to drilling, obtaining a 3D -wave ( ) and -wave velocity ( ) model down to reservoir depth is recommended. In the stimulation phase, we recommend to monitor and to locate seismicity with high precision (decametre) in real-time and to perform local 4D tomography for velocity ratio ( / ). During exploitation, one should use observed and model induced seismicity to forward estimate seismic hazard so that field operators are in a position to adjust well hydraulics (rate and volume of the fluid injected) when induced events start to occur far away from the boundary of the seismic cloud.

show abstract

Section: Introductionmentioning

confidence: 99%

Analysis of induced seismicity in geothermal reservoirs – An overview

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…Fluid injection causes stress field changes and re-activation of the pre-existing joints and slip of nearby faults which consequently can result in larger magnitude events, e.g. local magnitude of 3.4 event in Basel EGS operation (Kraft et al, 2009). These largest events tend to occur on the fringes, outside the "main cloud" of seismicity and are often observed after well shut-in, making them difficult to control (Mukuhira et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation on optimized stimulation of intact and naturally fractured deep geothermal reservoirs using hydro-mechanical coupled discrete particles joints model

2014

View full text Add to dashboard Cite

This numerical study investigates hydraulic fracturing and induced seismicity in intact and fractured reservoirs under anisotropic in situ stress using hydro-mechanical coupled discrete particles joints model. A 2 km 2 km reservoir model with granitic rock and joints properties is constructed. Various injection scenarios are tested which involve continuous and cyclic styles of pressure controlled and flow rate controlled injections. Results are compared which include: spatial and temporal evolution of induced seismic events in relation with fluid pressure distribution, moment magnitudes of the induced events, occurrence of post-shut-in large magnitude events, etc. Several field observations on induced seismicity phenomena are simulated which include creation of new fractures, reactivation of the pre-existing joints, post-shut-in seismicity and large magnitude event with non-double-couple source, Kaiser phenomenon, moment magnitude vs. frequency distribution of the induced events following the Gutenberg-Richter law, etc. Cyclic injection results in larger volume of injected fluid but less number of total events and larger magnitude events; hence less seismic energy radiated by the induced events, slower relaxation of the fluid pressure after shut-in, longer and thinner propagated fractures with larger fluid saturated area. The major conclusions of this study are that the presented modeling is capable of simulating induced seismicity phenomena in Enhanced Geothermal System and fluid injection in fractured reservoirs in cyclic way has potential in mitigating the effects of larger magnitude induced events.

show abstract

“…Both the extraction of hot water in deep boreholes and the reinjection of cold water in distant boreholes can generate a geothermal energy production cycle until the hot rocks deep underground (2-6km) cool down and the thermal energy source ceases. The production cycle, however, can be perturbed when too much fluid is extracted (see figure 5) or injected [65]. Large amounts of water masses can be removed or accumulated during the lifespan of a deep geothermal power plant.…”

Section: Geothermal Energy Productionmentioning

confidence: 99%

“…Their socioeconomic impacts, however, are disproportionally higher, because human-triggered earthquakes  only occur in regions close to the geoengineering activities, i.e., rural and urbanized areas,  occur mostly in naturally stable continental regions, with >90 percent of the world population,  nucleate in very shallow depths (0 − 20km), while damaging seismic energy can reach the Earth surface,  can create lasting seismic activities in areas that were initially stable (e.g., Australia, Europe) [23,65].…”

Section: How Do Human-triggered Earthquakes Affect Human Security?mentioning

confidence: 99%

Human-triggered earthquakes and their impacts on human security

Klose

2010

Nature Precedings

View full text Add to dashboard Cite

Abstract.A comprehensive understanding of earthquake risks in urbanized regions requires an accurate assessment of both urban vulnerabilities and earthquake hazards. Socioeconomic risks associated with human-triggered earthquakes are often misconstrued and receive little scientific, legal, and public attention. However, more than 200 damaging earthquakes, associated with industrialization and urbanization, were documented since the 20th century. This type of geohazard has impacts on human security on a regional and national level. For example, the 1989 Newcastle earthquake caused 13 deaths and US$3.5 billion damage (in 1989). The monetary loss was equivalent to 3.4 percent of Australia's national income (GDI) or 80 percent of Australia's GDI per capita growth of the same year. This article provides an overview of global statistics of humantriggered earthquakes. It describes how geomechanical pollution due to large-scale geoengineering activities can advance the clock of earthquakes or trigger new seismic events. Lastly, defense-oriented strategies and tactics are described, including risk mitigation measures such as urban planning adaptations and seismic hazard mapping.

show abstract

Enhanced Geothermal Systems: Mitigating Risk in Urban Areas

Cited by 69 publications

References 6 publications

Analysis of induced seismicity in geothermal reservoirs – An overview

Analysis of induced seismicity in geothermal reservoirs – An overview

Numerical investigation on optimized stimulation of intact and naturally fractured deep geothermal reservoirs using hydro-mechanical coupled discrete particles joints model

Human-triggered earthquakes and their impacts on human security

Contact Info

Product

Resources

About