Metals in geothermal fluids and metal precipitations in surface pipelines in Iceland can these been utilized? Dr. Vigdís Hardardóttir, Iceland GeoSurvey - ÍSOR Msc. NordMin course Iceland Nov. 2016
Black smokers and Reykjanes ~ 300 C downhole (1350, 1500 m), 2 cm/yr ~ 350 C ocean floor 2600 md, 6.2 cm/yr, po, cpy, sph ~ 360 C ocean floor 3670 md, 2.4 cm/yr,py, cpy, sph, am-sio 2 Up to 407 C ocean floor, 3000 md, 3.2 cm/yr, massive cpy, py py, cpy, isocu Breaking up of the continent ~60-70 million years ago Tivey 2008 Msc. NordMin course Iceland Nov. 2016 2
Mantle plume position through time 40 M y Reykjanes Ridge 30 M y 20 M y Today Kolbeinsey Ridge UK 400 km Saunders et al., 1997 Msc. NordMin course Iceland Nov. 2016 3
Volcanic systems in and surrounding Iceland Modified from Hjartarson & Erlendsson 2016 Msc. NordMin course Iceland Nov. 2016 4
Iceland Reykjanes Ridge Plate boundary Tholeiitic - Volcanic systems (No silicic rocks) variable crustal thickness From Hardardóttir et al. 2009 Msc. NordMin course Iceland Nov. 2016 5
Þingvellir Rifting Rifting and transcurrent faulting 30 to 40 oblique to the spreading direction resembling faster spreading ridges both in terms of topography and seismicity Msc. NordMin course Iceland Nov. 2016 6
Reykjanes Peninsula Elongated ridges and table mountains lacks central volcanos Msc. NordMin course Iceland Nov. 2016 7
Reykjanes Peninsula, SW Iceland: Oblique aerial photograph to ENE Reykjanes analogous to seafloor hydrothermal systems in terms of host rock type and low water/rock alteration modified seawater 270-340 C Area of surface features and wells of Reykjanes 1 km Msc. NordMin course Iceland Nov. 2016 8
Reykjanes Geothermal System Hardardottir 2011 Msc. NordMin course Iceland Nov. 2016 9
Reykjanes Geothermal System Hardardottir 2011 Msc. NordMin course Iceland Nov. 2016 10
Reykjanes Geothermal System Hardardottir 2011 Msc. NordMin course Iceland Nov. 2016 11
Sea floor high-temperature hydrothermal system Seawater recharge Layered gabbros Jeffrey C. Alt 1995, Sefloor Hydrothermal Systems in Susan E. Humphris et al Lavas, hyaloclastites and pillow basalts 2-3 km dikes heat source Sheeted dyke complex 4-5 km 6-7 km? 10 km Msc. NordMin course Iceland Nov. 2016 12
Geochemical Flywheel for the Oceans 1 2 7 7 1 2 C 1) cold seawater sinks into the seafloor along fissures 2) alteration of the oceanic crust at low temperatures (<150 C) clay and sulfate 3 4 5 6 100 C 300 C 400-450 C 3) Mg 2+ and OH - in the seawater are taken up by the host rocks; the ph-drops 4) precipitation of anhydrite takes up all of the Ca 2+ and most of the SO 4 2-5) Na, Ca and K are released into the fluid; leftover SO 4 2- is reduced to H 2 S; ph reaches ~ 3 and Cu, Zn, Fe, Au... and S are leached from the basalt 1200 C 6) The hot, metal-rich fluid ascends rapidly to the seafloor 7) massive sulfides form where hydrothermal fluids and cold seawater mix Msc. NordMin course Iceland Nov. 2016 13
Geochemical Alteration (ODP Hole 504B) Low-temperature K metasomatism Oxidation of basalt (reduction of seawater) Msc. NordMin course Iceland Nov. 2016 14
Power Plant: 100 Mwe Expansion plan 50 + 30 MWe The only seawater cooled geothermal power plant in the world boiled liquid in to the sea 29 16 10 13 11 14 1500 md, 296 C 12 21 1350 md, 284 C 34 drill holes drilled From Fridleifsson Msc. NordMin course Iceland Nov. 2016 19 1500 md, 15
North American plate Eurasian plate Borehole pressure logging 2 phase fluid First, downhole temperature and pressure measurements: Samples collected 1phase at 1350 m and fluid 1500 (284-296 C), below depth of first boiling Msc. NordMin course Iceland Nov. 2016 16
Butterfield et al., 1990; Von Damm et al., 1998, 2003; Douville et al., 2002; Hannington et al., 2005; Gallant & Von Damm, 2006; Koschinsky et al., 2008) Downhole mg/kg µg/kg Fe 9-141 Ni 150-550 Zn 5-27 As 100-150 Cu 14-17 Ag 30-100 Mn 2-3 Au 1-6 Pb 0.12-0.29 Reservoir liquid Msc. NordMin course Iceland Nov. 2016 Hardardottir et al., 2009: Metals in deep liquid of th Reykjanes geothermal system, southwest Iceland: Implications for the composition of seafloor black smoker fluids. 17
Differences similarities between RN-wells, 21 N and TAG Msc. NordMin course Iceland Nov. 2016 18
Upstream Wellhead RN9 Gray Lagoon Vent house Separation station Orifice plate Downstream 19 m G.O.Fridleifsson Msc. NordMin course Iceland Nov. 2016 19
Borehole pressure logging clogging 260 C 267 C 330 C Sph, cpy, gn, (bn, cv, py, Am SiO 2 ) Zn: 48-43 wt% Cu: 11-18 % Fe: 3-4 % Pb: 0.3-1% SiO2: 3-2% S: 30-28% Ag: 890-3500ppm Au:110-80 ppm Msc. NordMin course Iceland Nov. 2016 20
Borehole pressure logging RN-9 clogging Year Production, million ton Total production end of the year, million ton Average production, kg/s 1 Well million ton 2005 0.94 52.23 29.89 2006 14.36 66.60 455.47 1.89 2007 23.21 89.80 735.88 3.10 Msc. NordMin course Iceland Nov. 2016 21
Medium-pressure wells 5µm Cc RN-12 Zn = 20% Fe = 9% Cu = 23% Pb = 15% S = 22% 570 ppm Au 9200 ppm Ag Bornite, sphalerite, galena, chalcopyrite, covellite RN12, 314 C max in well, at wellhead 247 C; ΔP 15 bars, CuS Msc. NordMin course Iceland Nov. 2016 22
RN24, 285 C max in well, at wellhead 235 C; ΔP 10 bars, ZnS+Cu 5 FeS 24, bornite/ digenite SiO 2 +Fe, Mn, Al, Ca Ag 5 µm Msc. NordMin course Iceland Nov. 2016 galen a bornite/digenite, RN-24 Zn = 22% Fe = 8% Cu = 25% Pb = 16% S = 23% 340 ppm Au 17,800 ppm Ag 23
RN21 RN21, 285 C max in well, at wellhead 240 C; ΔP 11 bars, PbS covelite 5 µm Bornite, sphalerite, galena 5 cm RN-21 Zn = 24% Fe = 6% Cu = 24% Pb = 13% S = 23% RN21, 285 C highest, ΔP=15-22 bars, PbS 140 ppm Au Ag 5 µm Msc. NordMin course Iceland Nov. 2016 22,600 ppm Ag 24
Mass Accumulation in RN-9 RN-9 well1983-1993 11 t/year of sphalerite RN-9 surface pipeline 8 m 0.94 m 3 of scales in ~ 1 year 2.5 t of 0.6 t sphalerite 0.2 t of chalcopyrite 1.6 t of amorphous silica RN11+ RN22+ RN23 = 2.4 t Zn ~0.9 t ~0.3 t Cu, ~0.2 t Fe, 22 kg Pb, 5 kg Ag, 700 g Au Msc. NordMin course Iceland Nov. 2016 25
Workover on well RN-XX 17/4 4/5 2013
Msc. NordMin course Iceland Nov. 2016 27
A B C D E F, bottom Flow direction rdmin course Iceland Nov. 2016 28
#79B B
#79C #79C C D
Cpy Sph C The washout B
Results Traces of scale at ~1000-1100 m depth mainly sulfides (sphalerite/wurtzite (sph/wz), trace of pyrite (py), clay and magnetite (Mt) and hematite (Hm) from host-rock and liner seen Traces of scale at ~1560 m depth and down to pipe No.79 mainly clay and Mt and Hm (from host-rock and liner) Bottom pipe full of mater which is mainly sulfides (sph/wz, cpy, py), with metal flakes from the liner (Mt, Hm, minor amount), rock fragments Volume of scale in the pipe = 0.48 m 3 which equal to 1 mm of scale (if spread evenly inside pipe (with radius = 0.133 m) from 1100 m depth to the wellhead The main scale are likely located just above the boiling point (1100 m depth?) and at 675-680 m depth (where the slotted liner meets the production casing)
Reykjanes scales analogue to the mound on the ocean floor Black smoke seawater Chalcopyrite (CuFeS 2 ) Remnant Anhydrite Fe-Zn-sulfides SO 4 2- Ca 2+ 350-400 C SO 4 2- Anhydrite (CaSO 4 ) Outer marcasite crust Lateral vent (horizontal fracturing) Chalcopyrite (CuFeS 2 ) High-temperature fluid Sph, cpy, gn, (bn, cv, py, Am SiO 2 ) Zn: 48-43 wt% Cu: 11-18 % Fe: 3-4 % Pb: 0.3-1% SiO2: 3-2% S: 30-28% Ag: 890-3500ppm Au:110-80 ppm Msc. NordMin course Iceland Nov. 2016 33
Reykjanes sub-aerial geothermal system Similar to sea floor hydrothermal system (tectonics, rock types, fluid composition, T C) Sphalerite, chalcopyrite, pyrite, pyrrhotite, bornite, covelite. (No anhydrite at Reykjanes) Strong depletion of metals after boiling at RN Depletion of some metals in sea floor systems due to boiling? Msc. NordMin course Iceland Nov. 2016 34
Thank you for your attention Msc. NordMin course Iceland Nov. 2016 35