Hydraulic Stimulation and Geophysical Fracture Monitoring in the -Project J. Orzol (1) , R. Jung (1) , H. Buness (1) , T. Tischner (2) , R. Jatho (2) and P. Kehrer (2) (1): GGA-Institute, Hannover; (2): BGR, Hannover
Objective • supply geothermal heat for direct use • use one-well concepts thermal power: 2 MW flowrate: 25 m 3 /h temperature: 130 °C costs: 7.5 Mio €
GeneSys • sedimentary rocks • low porosity & permeability • create artificial geothermal systems (EGS) • transfer waterfrac technology to sediments • Is there a self propping mechanism for sediments? • fracture propagation in layered sediments? • ….
Stimulation operations • Injection of 20.000 m³ fresh water • Creation of a large fracture with high conductivity 400 120 ≈ 330 bar injection pressure at wellhead (bar) 300 injection rate (l/s) 80 50 l/s 200 40 100 0 0 27-Oct 28-Oct 29-Oct 30-Oct 31-Oct 1-Nov 2-Nov 3-Nov
Phillips et al. 2002
3 - component 4,5 Hz geophone Dreilingen Z1 Horstberg Z1 900 m 1800 m 10 PDAS (6-Kanal) 9 EDL (3-Kanal)
use seismic signals from perforator guns to: • calibrate velocity model • estimate detection level Foto: S. Baisch (seismic efficiency only vaguely known) • M ~ 0. to -0.5 (comparable to Soultz) charges (each 30 g)
Induced seismicity – temporal occurence number of events: 3 1 7 wellhead pressure (bar) flow rate (l/s) ~ 8600 m 3
Second Stimulation 400 100 80 300 Injektionsdruck (bar) Injektionsrate (l/s) 60 Not a single event! 200 40 100 20 0 0 6-Nov 7-Nov 8-Nov 9-Nov 10-Nov 11-Nov 12-Nov 13-Nov
Seismic Event 1.11., 13:13:11. all stations, z-component Q-con Event 13:13:11 / 13:24:29 Seismic Event 1.11., 13:24:29. EDL - stations, all components, bandpass 30 – 90 Hz.
Phillips et al. 2002
Mohr Circle 1200 µ =1 µ =0,85 Shear stress (bar) 800 Soultz 400 Horstberg 0 0 200 400 600 800 1000 1200 Normal stress (bar)
Self-potential & tiltmeter Dreilingen Z1 Horstberg Z1 …no clear correlation to hydraulic activities… 1 km geophones tilmeter self-potential
Tiltmeter Okt. | Nov. Nov. | Dez. 26.10. 28.10. 30.10. 1.11. 3.11. 5.11. 7.11. 9.11. 11.11. 13.11. 15.11. 17.11. 19.11. 21.11. 23.11. 25.11. 27.11. 29.11. 1.12. 3.12. 5.12. 7.12. 22.10. 24.10. Y - component N1 N4 N3 N2 tides 5 µrad ~ 5 µm/m stimulations Okt. | Nov. Nov. | Dez. 22.10. 24.10. 26.10. 28.10. 30.10. 1.11. 3.11. 5.11. 7.11. 9.11. 11.11. 13.11. 15.11. 17.11. 19.11. 21.11. 23.11. 25.11. 27.11. 29.11. 1.12. 5.12. 7.12. 3.12. X - component
outlook • demonstration project Hannover • 3.800 m deep well • massive waterfrac-tests • installation of a micro- seismic network in preparation F. Böker, 1994
Conclusions/Summary • propagtion of a large tensile fracture by injection of 20.000 m³ of fresh water • only very few events detected • Soultz-like events did not occur • low stress difference between S h and S v : presumably no shearing, tensile fracture • potentially numerous smaller events not detected • deeper observation wells desirable, but too costly • more experience from Hannover site 2007/2008
Estimate of 3500 24.9.03, ungestört fracture height 3600 Solling-Sdst. • fracture clearly 3700 depth (m) propagates through clay Teufe (m) ≈ 200 m ! stones 3800 Detfurth-Sdst. • vertical fracture extension approx. 200 m 3900 4000 130 140 150 160 Temperatur (°C) temperature (°C)
Recommend
More recommend
