Workreport 1997-57



Aänekosken Kivetyn kairanreikien KI-KR10 ja KI-KR11 geofysikaalisten reikämittausten tuloskäsittely ja rakennemallin tarkistus reikien KI-KR10 - KI-KR13 perusteella


Kai Front; Olli Okko; Pertti Hassinen



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1 Front, K., Okko, 0. & Hassinen, P., 1997. Interpretation of geophysical logging of
boreholes KI-KRlO and KI-KRll at the Kivetty site at Äänekoski and revision of the
1 bedrock model based on data from boreholes KI-KRlO - KI-KR13. Posiva, Work
Report 97-57, 63 p. + 9 app.

1 The Finnish power companies Teollisuuden Voima Oy and Imatran Voima Oy are
preparing for final disposal of the high-level nuclear fuel waste deep into the bedrock. The
Kivetty research site at Äänekoski is one of the four candidates selected for the detailed
1 site characterization conducted by Posiva Oy. This report describes the processing and
interpretation of standard single hole geophysical borehole logging carried out in the 600 m
long boreholes KR10 and KR11 cored in 1996 and geological description of the recently
1 cored boreholes KR12 and KR13 at the Kivetty site at Äänekoski.

1 Furthermore, the structural bedrock model of the Kivetty site was reviewed according to
the hydraulic conductivity measurements, and oriented fracture data of dipmeter, applied
in the 76 mm diameter borehole KR10 as well as according to the retlections obtained by

1 oriented borehole radar and VSP surveys.

Lithological units, different types of porphyritic granodiorite and granite with associated

1 dykes and short amphibolitic sections, are classified by the use of combined natural gamma
radiation, density and magnetic susceptibility information. Fracturing is analysed by the
interpretation of diflerent types of acoustic, density, resistivity and temperature logs. There

1 are typically 1 - 3 tight fractures per meter in the drilled borehole cores. Typically, the main
fracturing is associated within the uppermost 150 - 200 m of the core samples. In this depth
section, rusty and weathered fractures occur, especially along the borehole KR11. The tew
1 fractured sections are typically only 1 - 2 m Iong sections. They are located and described
along the boreholes KR10 and KR11 by combining the logs of t1uid temperature and salinity
together with the porosity and modulus of elasticity derived from the tuli wave form sonic
1 log and the visual observations at the core samples. The main exceptions in length of
fracturing are the 30 - 40 m long hydrothermally altered and weathered section at the depth
interval of 290 - 330 m in the borehole KR 12 and the altered fracturing with core loss
1 associated with the contact zone of amphibolitic rock and porhyritic granite at the core
depth of 320 - 325m in the borehole KR 13

1 According to hydraulic conductivity tcsts and attcnuation of both body and tubc waves in
the full waveform acoustic logs, 2 - 3 individual sections wcre considered locally signiiicant
fracturcd zoncs. Geometrically, orientcd fractures, the adjoining borehole radar and VSP
1 retlections of the fractured sections, and the hydraulic interference tcsts give incoherent
information. Thereforc, thc bedrock modcl is rc-evaluatcd according to thc largc-scalc

1 hydraulic connections and similarities in thc tcctonic and geological character in fracturcd
scctions in different borcholcs.

1 Key words: Gcophysical, structural bcdrock modcl, lithological unit, fracturing, hydraulic


Geofysikaalinen; rakennemalli; kivilaji; rikkonaisuus; vedenjohtavuus


Aänekosken Kivetyn kairanreikien KI-KR10 ja KI-KR11 geofysikaalisten reikämittausten tuloskäsittely ja rakennemallin tarkistus reikien KI-KR10 - KI-KR13 perusteella (pdf) (3.4 MB)


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