Hydrogeological characteristics of the Outokumpu Deep Drill Hole

Laura Ahonen, Riikka Kietäväinen, Nina Kortelainen, Ilmo T. Kukkonen, Arto Pullinen, Taru Toppi, Malin Bomberg, Merja Itävaara, Aura Nousiainen, Mari Nyyssönen, Marjo Öster

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleScientific

18 Citations (Scopus)

Abstract

Extensive hydrogeological studies on the Outokumpu Deep Drill Hole R2500, drilled in 2004-2005, have been carried out during both the drilling phase as well as the post-drilling period. The present paper introduces the main results and characteristics of deep fluids and gases in the 2516 m deep hole drilled into a Paleoproterozoic formation of metasediments, ophiolite-derived altered ultrabasic rocks and pegmatitic granite. The main hydrogeological experiments during drilling were the daily monitoring of drilling fluid electrical conductivity, pH, composition and consumption (loss) of drilling fluid, as well as targeted fluid sampling and hydraulic testing during drilling breaks with the drill stem method. Hydrogeological sampling of the drill hole water with a tube method has been carried out three times to up to 1500-2350 m depths in the post-drilling period, and undisturbed formation fluid was pumped for several weeks from a packer-isolated fracture system at 967 m. The loss of drilling water during drilling was very heavy in the uppermost 1000 m of the hole (1-4 m3 of water per 1 m of drilling), but it decreased to a low level (<1 m3/m) at lower depths, indicating that hydraulically conductive fractures are more frequent in the first kilometre of bedrock than beneath. The hydraulic testing carried out at approximately 500-m depth intervals in 40-70 m thick sections indicated a similar pattern of hydraulic conductivity decreasing with depth: about 7.5 ·10-6 m/s at 500 m, 5.3 · 10-7 m/s at 1000 m, and practically impermeable rock at deeper levels. The electrical conductivity of the drill hole fluid rapidly increased in the post-drilling period due to the discharge of saline water from several fracture systems, and was monitored with repeated down-hole logs. In the uppermost 1000 m, fluid salinity has been in a semi-stable condition since about 2006, but in the deeper parts of the hole electrical conductivity continued to gradually increase in 2008 and 2009, when the most recent downhole logs and fluid sample profiles were obtained. The fluids are Ca-Na-Cl fluids with elevated Mg concentrations at the depths of the ophiolite-derived rocks of the Outokumpu assemblage. The fluids contain abundant gases, with methane and nitrogen being the main components. The stable isotope compositions (d2H, d18O) of the saline fluids indicate that they are not meteoric fluids but probably result from long-term water-rock interaction. The results indicate distinct water bodies isolated in fracture zones with minimal hydraulic connections.
Original languageEnglish
Title of host publicationOutokumpu Deep Drilling Project 2003-2010
EditorsIlmo T. Kukkonen
Place of PublicationEspoo
Pages151-168
Publication statusPublished - 2011
MoE publication typeB2 Part of a book or another research book

Fingerprint

drilling
fluid
electrical conductivity
drilling fluid
hydraulics
ophiolite
rock
water
water-rock interaction
sampling
metasediment
fracture zone
gas
hydraulic conductivity
bedrock
stable isotope
granite
methane
stem
salinity

Keywords

  • deep drilling
  • boreholes
  • bedrock
  • hydrogeology
  • ground water
  • hydrochemistry
  • salt water
  • stable isotopes
  • gases
  • hydraulic conductivity
  • Outokumpu
  • Finland

Cite this

Ahonen, L., Kietäväinen, R., Kortelainen, N., Kukkonen, I. T., Pullinen, A., Toppi, T., ... Öster, M. (2011). Hydrogeological characteristics of the Outokumpu Deep Drill Hole. In I. T. Kukkonen (Ed.), Outokumpu Deep Drilling Project 2003-2010 (pp. 151-168). Espoo.
Ahonen, Laura ; Kietäväinen, Riikka ; Kortelainen, Nina ; Kukkonen, Ilmo T. ; Pullinen, Arto ; Toppi, Taru ; Bomberg, Malin ; Itävaara, Merja ; Nousiainen, Aura ; Nyyssönen, Mari ; Öster, Marjo. / Hydrogeological characteristics of the Outokumpu Deep Drill Hole. Outokumpu Deep Drilling Project 2003-2010. editor / Ilmo T. Kukkonen. Espoo, 2011. pp. 151-168
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abstract = "Extensive hydrogeological studies on the Outokumpu Deep Drill Hole R2500, drilled in 2004-2005, have been carried out during both the drilling phase as well as the post-drilling period. The present paper introduces the main results and characteristics of deep fluids and gases in the 2516 m deep hole drilled into a Paleoproterozoic formation of metasediments, ophiolite-derived altered ultrabasic rocks and pegmatitic granite. The main hydrogeological experiments during drilling were the daily monitoring of drilling fluid electrical conductivity, pH, composition and consumption (loss) of drilling fluid, as well as targeted fluid sampling and hydraulic testing during drilling breaks with the drill stem method. Hydrogeological sampling of the drill hole water with a tube method has been carried out three times to up to 1500-2350 m depths in the post-drilling period, and undisturbed formation fluid was pumped for several weeks from a packer-isolated fracture system at 967 m. The loss of drilling water during drilling was very heavy in the uppermost 1000 m of the hole (1-4 m3 of water per 1 m of drilling), but it decreased to a low level (<1 m3/m) at lower depths, indicating that hydraulically conductive fractures are more frequent in the first kilometre of bedrock than beneath. The hydraulic testing carried out at approximately 500-m depth intervals in 40-70 m thick sections indicated a similar pattern of hydraulic conductivity decreasing with depth: about 7.5 ·10-6 m/s at 500 m, 5.3 · 10-7 m/s at 1000 m, and practically impermeable rock at deeper levels. The electrical conductivity of the drill hole fluid rapidly increased in the post-drilling period due to the discharge of saline water from several fracture systems, and was monitored with repeated down-hole logs. In the uppermost 1000 m, fluid salinity has been in a semi-stable condition since about 2006, but in the deeper parts of the hole electrical conductivity continued to gradually increase in 2008 and 2009, when the most recent downhole logs and fluid sample profiles were obtained. The fluids are Ca-Na-Cl fluids with elevated Mg concentrations at the depths of the ophiolite-derived rocks of the Outokumpu assemblage. The fluids contain abundant gases, with methane and nitrogen being the main components. The stable isotope compositions (d2H, d18O) of the saline fluids indicate that they are not meteoric fluids but probably result from long-term water-rock interaction. The results indicate distinct water bodies isolated in fracture zones with minimal hydraulic connections.",
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author = "Laura Ahonen and Riikka Kiet{\"a}v{\"a}inen and Nina Kortelainen and Kukkonen, {Ilmo T.} and Arto Pullinen and Taru Toppi and Malin Bomberg and Merja It{\"a}vaara and Aura Nousiainen and Mari Nyyss{\"o}nen and Marjo {\"O}ster",
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pages = "151--168",
editor = "Kukkonen, {Ilmo T.}",
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Ahonen, L, Kietäväinen, R, Kortelainen, N, Kukkonen, IT, Pullinen, A, Toppi, T, Bomberg, M, Itävaara, M, Nousiainen, A, Nyyssönen, M & Öster, M 2011, Hydrogeological characteristics of the Outokumpu Deep Drill Hole. in IT Kukkonen (ed.), Outokumpu Deep Drilling Project 2003-2010. Espoo, pp. 151-168.

Hydrogeological characteristics of the Outokumpu Deep Drill Hole. / Ahonen, Laura; Kietäväinen, Riikka; Kortelainen, Nina; Kukkonen, Ilmo T.; Pullinen, Arto; Toppi, Taru; Bomberg, Malin; Itävaara, Merja; Nousiainen, Aura; Nyyssönen, Mari; Öster, Marjo.

Outokumpu Deep Drilling Project 2003-2010. ed. / Ilmo T. Kukkonen. Espoo, 2011. p. 151-168.

Research output: Chapter in Book/Report/Conference proceedingChapter or book articleScientific

TY - CHAP

T1 - Hydrogeological characteristics of the Outokumpu Deep Drill Hole

AU - Ahonen, Laura

AU - Kietäväinen, Riikka

AU - Kortelainen, Nina

AU - Kukkonen, Ilmo T.

AU - Pullinen, Arto

AU - Toppi, Taru

AU - Bomberg, Malin

AU - Itävaara, Merja

AU - Nousiainen, Aura

AU - Nyyssönen, Mari

AU - Öster, Marjo

PY - 2011

Y1 - 2011

N2 - Extensive hydrogeological studies on the Outokumpu Deep Drill Hole R2500, drilled in 2004-2005, have been carried out during both the drilling phase as well as the post-drilling period. The present paper introduces the main results and characteristics of deep fluids and gases in the 2516 m deep hole drilled into a Paleoproterozoic formation of metasediments, ophiolite-derived altered ultrabasic rocks and pegmatitic granite. The main hydrogeological experiments during drilling were the daily monitoring of drilling fluid electrical conductivity, pH, composition and consumption (loss) of drilling fluid, as well as targeted fluid sampling and hydraulic testing during drilling breaks with the drill stem method. Hydrogeological sampling of the drill hole water with a tube method has been carried out three times to up to 1500-2350 m depths in the post-drilling period, and undisturbed formation fluid was pumped for several weeks from a packer-isolated fracture system at 967 m. The loss of drilling water during drilling was very heavy in the uppermost 1000 m of the hole (1-4 m3 of water per 1 m of drilling), but it decreased to a low level (<1 m3/m) at lower depths, indicating that hydraulically conductive fractures are more frequent in the first kilometre of bedrock than beneath. The hydraulic testing carried out at approximately 500-m depth intervals in 40-70 m thick sections indicated a similar pattern of hydraulic conductivity decreasing with depth: about 7.5 ·10-6 m/s at 500 m, 5.3 · 10-7 m/s at 1000 m, and practically impermeable rock at deeper levels. The electrical conductivity of the drill hole fluid rapidly increased in the post-drilling period due to the discharge of saline water from several fracture systems, and was monitored with repeated down-hole logs. In the uppermost 1000 m, fluid salinity has been in a semi-stable condition since about 2006, but in the deeper parts of the hole electrical conductivity continued to gradually increase in 2008 and 2009, when the most recent downhole logs and fluid sample profiles were obtained. The fluids are Ca-Na-Cl fluids with elevated Mg concentrations at the depths of the ophiolite-derived rocks of the Outokumpu assemblage. The fluids contain abundant gases, with methane and nitrogen being the main components. The stable isotope compositions (d2H, d18O) of the saline fluids indicate that they are not meteoric fluids but probably result from long-term water-rock interaction. The results indicate distinct water bodies isolated in fracture zones with minimal hydraulic connections.

AB - Extensive hydrogeological studies on the Outokumpu Deep Drill Hole R2500, drilled in 2004-2005, have been carried out during both the drilling phase as well as the post-drilling period. The present paper introduces the main results and characteristics of deep fluids and gases in the 2516 m deep hole drilled into a Paleoproterozoic formation of metasediments, ophiolite-derived altered ultrabasic rocks and pegmatitic granite. The main hydrogeological experiments during drilling were the daily monitoring of drilling fluid electrical conductivity, pH, composition and consumption (loss) of drilling fluid, as well as targeted fluid sampling and hydraulic testing during drilling breaks with the drill stem method. Hydrogeological sampling of the drill hole water with a tube method has been carried out three times to up to 1500-2350 m depths in the post-drilling period, and undisturbed formation fluid was pumped for several weeks from a packer-isolated fracture system at 967 m. The loss of drilling water during drilling was very heavy in the uppermost 1000 m of the hole (1-4 m3 of water per 1 m of drilling), but it decreased to a low level (<1 m3/m) at lower depths, indicating that hydraulically conductive fractures are more frequent in the first kilometre of bedrock than beneath. The hydraulic testing carried out at approximately 500-m depth intervals in 40-70 m thick sections indicated a similar pattern of hydraulic conductivity decreasing with depth: about 7.5 ·10-6 m/s at 500 m, 5.3 · 10-7 m/s at 1000 m, and practically impermeable rock at deeper levels. The electrical conductivity of the drill hole fluid rapidly increased in the post-drilling period due to the discharge of saline water from several fracture systems, and was monitored with repeated down-hole logs. In the uppermost 1000 m, fluid salinity has been in a semi-stable condition since about 2006, but in the deeper parts of the hole electrical conductivity continued to gradually increase in 2008 and 2009, when the most recent downhole logs and fluid sample profiles were obtained. The fluids are Ca-Na-Cl fluids with elevated Mg concentrations at the depths of the ophiolite-derived rocks of the Outokumpu assemblage. The fluids contain abundant gases, with methane and nitrogen being the main components. The stable isotope compositions (d2H, d18O) of the saline fluids indicate that they are not meteoric fluids but probably result from long-term water-rock interaction. The results indicate distinct water bodies isolated in fracture zones with minimal hydraulic connections.

KW - deep drilling

KW - boreholes

KW - bedrock

KW - hydrogeology

KW - ground water

KW - hydrochemistry

KW - salt water

KW - stable isotopes

KW - gases

KW - hydraulic conductivity

KW - Outokumpu

KW - Finland

M3 - Chapter or book article

SN - 978-952-217-151-1

SN - 978-952-217-152-8

SP - 151

EP - 168

BT - Outokumpu Deep Drilling Project 2003-2010

A2 - Kukkonen, Ilmo T.

CY - Espoo

ER -

Ahonen L, Kietäväinen R, Kortelainen N, Kukkonen IT, Pullinen A, Toppi T et al. Hydrogeological characteristics of the Outokumpu Deep Drill Hole. In Kukkonen IT, editor, Outokumpu Deep Drilling Project 2003-2010. Espoo. 2011. p. 151-168