TY  - JOUR
ID  - epos2260
UR  - https://doi.org/10.1785/0120140208
IS  - 1
A1  - Baisch, Stefan
A1  - Rothert, Elmar
A1  - Stang, Henrik
A1  - Vörös, Robert
A1  - Koch, Christopher
A1  - McMahon, Andrew
Y1  - 2015///
N2  - Two fluid injection experiments were conducted in the Cooper Basin, Australia, in 2010 and 2012. Following previous stimulations in the Habanero reservoir, approximately 34,000??m3 of water were injected into the granitic crust at 4160 m depth through the Habanero 4 well. More than 29,000 induced seismic events were recorded by a local 24?station network. Event magnitudes are in the range between ML?1.6 and 3.0. Hypocenter locations could be determined for 21,720 events. The spatial hypocenter distribution indicates that the seismicity occurred on the same subhorizontal layer structure identified previously. Fault?plane solutions determined for 525 of the strongest events are mostly consistent with the regional stress field acting on a larger scale fracture zone with an orientation as outlined by the hypocenter distribution. The fracture zone is interpreted to be of tectonic origin. Large stress accumulations near a reservoir boundary indicate that the hypocenter distribution is bounded by a structural limit of the fracture zone.

High?pressure stimulation at similar depth in a nearby well caused only minor seismic activity. During an eight?day stimulation period, less than 80 induced seismic events were recorded followed by another 139 events over the next six months. The maximum event magnitude was ML 1.6. Hypocenters are located in close vicinity of the injection well and align along steeply dipping fractures consistent with their fault mechanisms. These fractures are not well oriented for shearing in the regional stress field. They were seismically activated at extremely large overpressures and accepted only small amounts of fluid. Our findings indicate that natural flowing fractures play a key role for hydraulic stimulations in the crystalline crust.

GeoRef Subject
Cooper Basin Australia crust Australasia faults earthquakes geothermal energy South Australia Queensland Australia
PB  - Seismological Society of America
JF  - Bulletin of the Seismological Society of America
VL  - 105
SN  - 0037-1106
TI  - Continued Geothermal Reservoir Stimulation Experiments in the Cooper Basin (Australia)
SP  - 198
AV  - none
EP  - 209
ER  -