Characterizing the Mechanics of Fracturing from Earthquake Source Parameter and Multiplet Analyses: Application to the Soultz-sous-Forêts Hot Dry Rock site
نویسندگان
چکیده
In 2000 and 2003, two massive hydraulic fracturing experiments were carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The objective was to create a dense network of enhanced permeability fractures, which would form the heat exchanger. The injection of water in the fractured rock generated a high level of microseismic activity: around 30,000 and 90,000 micro-earthquakes were triggered during the injection of 2000 and 2003 respectively. From this around 14,000 and 9,000 events were then located to characterize the extent of the stimulated zones and hence of the fracture network. Then, the source parameters of each event, like seismic moments and stress drops, were computed automatically to characterize the mechanics of the fracturing. We found for example that the total seismic moment released is proportional to the injected fluid volume. This suggests that the injection flow rate could be a means to control the earthquake strength released during the stimulation and perhaps also control the effectiveness of the stimulation. Finally, we performed a multiplet analysis of a subset of these data to identify microearthquakes having similar waveforms. Multiplets are considered to be microearthquakes that occur on the same fracture plane and therefore may represent either seismically activated structures and/or permeable fractures induced by hydraulic fracturing. We identified 350 multiplets among 1000 analyzed events. We relocated them precisely by cross-spectrum analysis and found that they belong to sub-horizontal structures, likely permeable fractures stimulated by the injection.
منابع مشابه
Impact of Induced Thermal Stresses During Circulation Tests in an Engineered Fractured Geothermal Reservoir Example of the Soultz-sous-Forêts European Hot Fractured Rock Geothermal Project, Rhine Graben, France
Impact of Induced Thermal Stresses during Circulation Tests in an Engineered Fractured Geothermal Reservoir: Example of the Soultz-sous-Forêts European Hot Fractured Rock Geothermal Project, Rhine Graben, France — The wider concept of hot fractured rock geothermal energy is put forward to overcome the natural limitations of classic geothermal fields. A suite of numerical modules based on a disc...
متن کاملFracture Mapping in the Soultz-sous-Forêts geothermal field from Microearthquake relocation
In 2003, a massive hydraulic fracturing experiment was carried out at the European Geothermal Hot Dry Rock site at Soultz-sous-Forêts, France. The two week injection of water generated a high level of microseismic activity. About 90,000 microearthquakes were triggered during and after this fluid injection. Of these, 21,000 events, detected at all stations, were located individually with a grid ...
متن کاملThe Soultz-sous-Forêts’ Enhanced Geothermal System: A Granitic Basement Used as a Heat Exchanger to Produce Electricity
متن کامل
Hydrothermally Altered and Fractured Granite as an Hdr Reservoir I N the Eps-1 Borehole, Alsace, France
As part of the European Hot Dry Rocks Project, a second exploration borehole, EPS-1, has been cored to a depth of 2227 m at Soultz-sous-For@ts (France). The target was a granite beginning at 1417 m depth, overlain by post-Paleozoic sedimentary cover. Structural analysis and petrographic examination of the 800-111 porphyritic granite core, have shown that this rock has undergone several periods ...
متن کاملEstimation of Fine Scale Structures in Soultz Hdr Reservoir by Using Microseismic Multiplets
Microseismic multiplet has been used to estimate detailed structures of deep reservoir at Soultz HDR field, France. The multiplet is a group of microseismic events with similar waveforms in spite of different origin times. A hydraulic fracturing experiment was carried out at Soultz in 2000, and the artificial geothermal reservoir was created around the depth of 5,000 m. The induced microseismic...
متن کامل