TY  - JOUR
ID  - epos1350
UR  - http://dx.doi.org/10.1007/s00024-008-0335-7
IS  - 5
A1  - Cuenot, Nicolas
A1  - Dorbath, Catherine
A1  - Dorbath, Louis
N2  - In June/July 2000, a hydraulic stimulation experiment took place at the geothermal EGS site of Soultz-sous-Forêts (Alsace, France) in order to enhance the permeability of the fractured granitic massif at 5 km depth. As it is well known that fluid injections tend to induce microseismic events, a downhole and a surface seismological network have been installed to monitor the seismic activity during the stimulation test. 23400 m3 of fluid have been injected in the rock volume through the open-hole section (4400 m?5000 m) of the well GPK2 at increasing rates of 30 l.s?1, 40 l.s?1 and then 50 l.s?1. More than 7200 microseismic events in the magnitude range ?0.9 to 2.6 have been precisely located through a simultaneous inversion of the seismic velocity structure and location parameters. The analysis of the behavior of the seismicity relative to the hydraulic parameters gives important information about the geothermal reservoir. It appears that the evolution of the seismicity strongly depends on the variations of the injection rate: An increase or a decrease leads to changes of the velocity structure, the number and magnitude of microseismic events. This involves different hydro-mechanical processes between the fluid flow and the fracture planes, which will control the final shape of the microseismic cloud. Moreover, the study of the variations of the b-value with time suggests that the stimulation experiment produces a large proportion of small earthquakes, but records of events of magnitude higher than 2 indicate that fluid injection could reactivate structures whose dimensions allow the generation of such earthquakes.
VL  - 165
TI  - Analysis of the Microseismicity Induced by Fluid Injections at the EGS Site of Soultz-sous-Forêts (Alsace, France): Implications for the Characterization of the Geothermal Reservoir Properties
AV  - none
EP  - 828
Y1  - 2008///
PB  - Springer Verlag
JF  - Pure and Applied Geophysics
KW  - Geothermal reservoir
KW  -  hydraulic stimulation
KW  -         microseismicity
KW  -  velocity structure
KW  -  b-value
SN  - 0033-4553
SP  - 797
ER  -