THE SOULTZ EGS PROJECT AND
ITS SOCIAL ENVIRONMENT:
HOW TO REDUCE THE RISK OF
PUBLIC OPPOSITION
Nicolas CUENOT & Daniel FRITSCH
GEIE “Exploitation Minière de la Chaleur” / EEIG “Heat Mining”
Route de Soultz – BP 38 – 67250 Kutzenhausen – France
Tel.: +33 3 88 80 53 63 / Fax : +33 3 88 80 53 51 / www.soultz.net
Corresponding author: cuenot@soultz.net
OUTLINE:
 Hydraulic
stimulations and induced seismicity
 Consequences for public acceptance
 Scientific research on larger magnitude events
 Scientific cooperation
 Use of other stimulation techniques
 Communication
Hydraulic stimulation and induced seismicity
 4 massive hydraulic stimulation experiments
Injected
volume
Maximum flow rate
Maximum
overpressure
Induced
seismicity
Larger
magnitude
events
13 MPa
~14000
(located)
75 (M≥1.8)
1 x 2.6
2 x 2.4
43 (M≥1.8)
1 x 2.9
2 x 2.7
GPK2 (2000) ~23400 m3
50 l/s
GPK3 (2003) ~34000 m3
50 l/s; 60 & 90 l/s
“Focused stimulation”
18 MPa
~22000
(located)
GPK4 (2004) ~9300 m3
45 l/s
17 MPa
~5800
(located)
3 (M≥1.8)
1 x 2.0
19 MPa
~3000
(located)
17 (M≥1.8)
1 x 2.6
1 x 2.3
GPK4 (2005) ~12300 m3
45 l/s
Hydraulic stimulation and induced seismicity
Consequences for public acceptance
 growing fear due to:
• the largest earthquakes (vibration, sound, moving objects)
• repetition of felt earthquakes (within a short period and from one
stimulation test to another)
 lots of phone calls (complain or ask for information)
 complaints to local authorities from individuals or associations
 articles in local newspapers
 around 30 complaints for presumed damages, which were evaluated by
experts from insurance companies
 long-term risk of strong opposition to the project
Scientific research
First action → scientific research to understand the occurrence
of the stronger earthquakes:
 presence of large faults, able to produce seismic events of
such magnitudes
 high stress drop: strong energy release on small fractures
From Dorbath et al., 2007
Scientific research
Other actions:
 Installation by EOST of a permanent surface seismological
network before the stimulation of GPK3
 Installation of surface accelerometers at different places in
Soultz to monitor the effective ground acceleration
From Dorbath et al., 2007
Scientific research
International cooperation
 creation of an independent experts group,
which is in charge to evaluate the stimulations
programs in terms of seismic risk
 participation to different workshops on induced
seismicity
 creation of an EHDRA workgroup “Seismohydraulics”: 4 meetings were organized to
discuss issues related to stimulation processes
 Organization of a yearly EHDRA Scientific
Meeting, with at least one session dedicated to
microseismicity
Technical measures
In order to limit the induced earthquakes in terms of number and
magnitude, we try to act on the medium by performing chemical
stimulations instead of pure hydraulic stimulations, as we know
that the fractures are sealed by hydrothermal deposits (calcite,
silica and clays)
 a one-year program was built with the help of geochemists and
companies, which have experience in chemical stimulation
 GPK4 was the target, as this well exhibited a low productivity
index after the 6-months circulation test
 RMA (Regular Mud Acid) in May 2006; max flow rate: 28 l/s,
aiming at dissolving minerals like clay, feldspars and mica.
 Chelatants (NTA) in October 2006; max flow rate: 40 l/s, aiming
at acting on calcite
 OCA (Organic Clay Acid) in February 2007; max flow rate: 55
l/s, used in high temperature medium with high clay content.
Technical measures
Results of the chemical stimulation program:
 Improvement of the productivity of the well
 lower volume of injected fluids; Lower flow rates,
except for short periods (“flush”) → lower
overpressures
 RMA: ~20 seismic events, highest magnitude: 1.9,
but the earthquake was not felt.
 NTA: no seismicity
 OCA: ~80 seismic events, highest magnitude: 1.5
 direct consequence: NO complaint from the
population and a more peaceful environment around
the project
Upper figure: seismicity during the RMA test
Lower figure: seismicity during the OCA test
both from EOST (J. Charléty & L. Dorbath)
Communication
 Before any stimulation test, a information
letter is sent to the population to present the
stimulation program and the possibility of
induced seismicity
 Following the strongest event, public
information meetings were organized by the
EEIG with the participation of seismologists
to explain the stimulation tests and to give
more precise information about induced
seismicity and, to a larger extent,
seismology
 A small macroseismic investigation was
achieved after the M=2.9 earthquake to get
information about how people felt the
vibrations
 Accelerometers were installed in the
Police buildings and in the cellar of one
inhabitant’s house to record the effective
ground acceleration (presumed site effect)
Communication
 Organization of a public information
meeting every 2 months to present the
project
• 40 to 50 people at each meeting,
mainly students and local population
• numerous questions about the
project, and mainly about earthquakes
• people looks very interested and
satisfied after the meetings
 Organization of special information
meetings for associations, groups of
students, companies…
 Publication of a regular 2-folds
newspaper, which is written in 3 languages
and distributed to a large audience to
present the development of the project and
the main events.
 The Web site is regularly updated.
Conclusions
 Working on three different ways contributed to significantly increase
the social acceptability by producing a more quiet environment around
the project for 2 years now:
• Scientific → better understanding of induced seismicity
• Technical → use of low seismicity-inducing stimulation techniques
• Communication → better information to a motivated population
 The population and local authorities now fully supports the project,
since they noticed that we are doing our best to avoid the possible
nuisances, or at least, to inform them honestly about them
 For the future, once people will see the concrete achievement of our
project (and others), they will be able to make a better balance between
the benefits given by geothermal projects and the possible disturbances
related to their development.