geophysical drillhole logging and imaging of drillholes ol ......suomen malmi oy conducted...

P O S I V A O Y

O l k i l u o t o

F I -27160 EURAJOKI , F INLAND

Te l +358-2-8372 31

Fax +358-2-8372 3809

Anna -Mar ia Tarva inen

Eero He ikk inen

August 2011

Work ing Repor t 2011 -58

Geophysical Drillhole Logging and Imaging ofDrillholes OL-KR54, OL-KR55 and OL-KR55B

at Olkiluoto in 2010 and 2011

August 2011

Working Reports contain information on work in progress

or pending completion.

The conclusions and viewpoints presented in the report

are those of author(s) and do not necessarily

coincide with those of Posiva.

Anna -Mar ia Tarva inen

Suomen Ma lm i Oy

Eero He ikk inen

Pöyry F in l and Oy

Work ing Report 2011 -58

Geophysical Drillhole Logging and Imaging ofDrillholes OL-KR54, OL-KR55 and OL-KR55B

at Olkiluoto in 2010 and 2011

GEOPHYSICAL DRILLHOLE LOGGING AND IMAGING OF DRILLHOLES OL-KR54, OL-KR55 AND OL-KR55B AT OLKILUOTO IN 2010 AND 2011

ABSTRACT

Suomen Malmi Oy conducted geophysical drillhole logging as well as optical and acoustic imaging of the drillholes OL-KR54, OL-KR55 and OL-KR55B at the Olkiluoto site in Eurajoki between August 2010 and January 2011. The survey is a part of Posiva Oy’s detailed investigation program for the final disposal of spent nuclear fuel. The assignment included the field work and data processing. The report describes field operation, equipment as well as processing procedures and shows the obtained results and an analysis of their quality in the appendices. New focused resistivity, susceptibility, natural gamma and density probes were tested and compared with old probes. This report describes the major features of new probes and the comparison with old probes. The raw and processed data are delivered digitally in WellCAD, PDF and Excel format. Keywords: Geophysics, drillhole logging, structural geology, nuclear waste disposal.

GEOFYSIKAALISET REIKÄMITTAUKSET JA KUVAUKSET KAIRAREI'ISSÄ OL-KR54, OL-KR55 JA OL-KR55B OLKILUODOSSA VUOSINA 2010–2011 TIIVISTELMÄ

Suomen Malmi Oy teki geofysikaalisia mittauksia sekä optista- ja akustista reikä-kuvausta kairarei’issä OL-KR54 ja OL-KR55 ja OL-KR55B Olkiluodon tutkimus-alueella elokuusta 2010 tammikuuhun 2011. Työ tehtiin Posiva Oy:n tilauksesta osana yksityiskohtaisia kallioperätutkimuksia käytetyn polttoaineen loppusijoitusta varten. Toimeksiantoon kuuluivat kenttätyöt ja tulosten prosessointi. Raportissa on kuvattu kenttätöiden kulku, käytetty kalusto ja tehdyt korjaukset sekä esitetty tulosten laatu liitteissä. Uudet resistiivisyys-, tiheys- ja suskeptibiliteettianturit testattiin ja mittaus-tuloksia verrattiin vanhojen antureiden vastaaviin. Tässä raportissa käsitellään uusien antureiden tärkeimmät ominaisuudet ja vertailu vanhojen antureiden kanssa. Tulokset on toimitettu tilaajalle digitaalisesti WellCAD-, PDF- ja Excel-muotoisina tiedostoina. Avainsanat: Geofysiikka, reikämittaukset, rakennegeologia, ydinjätteen loppusijoitus.

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TABLE OF CONTENTS ABSTRACT TIIVISTELMÄ

1� INTRODUCTION .................................................................................................... 3�

2� EQUIPMENT AND METHODS ............................................................................... 5�

2.1� Wellmac Logging System .............................................................................. 5�

2.2� Geovista Slimhole Density Sonde ................................................................. 6�

2.3� QL40 MagSus Magnetic Susceptibility Sonde .............................................. 6�

2.4� Geovista Dual Guard Focused Resistivity Sonde ......................................... 6�

2.5� Mount Sopris Caliper and Temperature-Fluid Resistivity Probes ................. 6�

2.6� ALT FWS50 Full Waveform Sonic Tool ........................................................ 7�

2.7� ALT OBI40 Slimhole Optical Televiewer ....................................................... 7�

2.8� ALT ABI40 Slimhole Acoustic televiewer ...................................................... 7�

3� FIELD WORK.......................................................................................................... 9�

4� PROCESSING AND RESULTS ............................................................................ 11�

4.1� Natural gamma radiation ............................................................................. 11�

4.2� Gamma-gamma density .............................................................................. 12�

4.3� Magnetic susceptibility ................................................................................ 12�

4.4� Focused resistivity ....................................................................................... 13�

4.5� Fluid temperature and resistivity ................................................................. 14�

4.6� Caliper ......................................................................................................... 15�

4.7� Full Waveform Sonic ................................................................................... 15�

4.8� Optical drillhole image ................................................................................. 17�

4.9� Acoustic drillhole image .............................................................................. 18�

5� COMPARISON OF RESISTIVITY, SUSCEPTIBILITY, NATURAL GAMMA AND DENSITY MEASUREMENTS WITH NEW AND OLD PROBES .................. 19�

5.1� Resistivity measurements ........................................................................... 19�

5.2� Susceptibility measurements ...................................................................... 21�

5.3� Natural gamma and density measurements ............................................... 22�

6� CONCLUSIONS.................................................................................................... 27�

REFERENCES ............................................................................................................. 29�

APPENDICES Appendix 1: Timing of the field work..............................................................................31 Appendix 2: Results ....................... ...............................................................................33

Appendix 2.1 OL-KR54 Appendix 2.1.1 Drillhole logging ................................................................. 34 Appendix 2.1.2 Fluid Properties .................................................................. 39

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Appendix 2.1.3 Acoustic Logging ............................................................... 44 Appendix 2.1.4 Acoustic Image................................................................... 50 Appendix 2.1.5 Acoustic Hole Imaging, ABI ................................................ 55 Appendix 2.1.6 Optical Hole Imaging, OBI, an example ............................. 61

Appendix 2.2 OL-KR55

Appendix 2.2.1 Drillhole logging ................................................................. 63 Appendix 2.2.2 Fluid Properties .................................................................. 73 Appendix 2.2.3 Acoustic Logging ............................................................... 83 Appendix 2.2.4 Acoustic Image................................................................... 94 Appendix 2.2.5 Acoustic Hole Imaging, ABI .............................................. 104

Appendix 2.3 OL-KR55B

Appendix 2.3.1 Drillhole logging ............................................................... 117 Appendix 2.3.2 Fluid Properties ................................................................ 118 Appendix 2.3.3 Acoustic Logging ............................................................. 119 Appendix 2.3.4 Acoustic Image................................................................. 120

Appendix 3: Tool technical information . ......................................................................121

Appendix 3.1 Wellmac Logging System ................................................... 121 Appendix 3.2 Geovista Slimhole Density Sonde ....................................... 123 Appendix 3.3 QL40 MagSus Magnetic Susceptibility Probe ..................... 124 Appendix 3.4 Geovista Dual Guard Focused Resistivity Sonde ............... 125 Appendix 3.5 Mount Sopris 3-Arm Caliper and Temperature-Fluid Resistivity Sonde ........................................................ 126 Appendix 3.6 ALT FWS50 Full Waveform Sonic Tool ............................. 127 Appendix 3.7 ALT OBI40 Slimhole Optical Televiewer ............................. 129 Appendix 3.8 ALT OBI40 Slimhole Acoustic Televiewer ........................... 131

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1 INTRODUCTION

In 1999, Posiva Oy filed an application for a policy decision from the council of state for a construction permit to build a final disposal facility for spent fuel at the Olkiluoto area in the Eurajoki municipality. In December 2000, the Council of State made a positive policy decision and in May 2001, the Parliament ratified the decision. The policy makes it possible to concentrate the research activities at Olkiluoto. Suomen Malmi Oy (Smoy) carried out geophysical drillhole surveys, optical drillhole imaging and acoustic drillhole imaging in drillholes OL-KR54, OL-KR55 and OL-KR55B. The assignment included various geophysical surveys and acoustic data interpretation according to a purchase order 9163-09. The drillhole geophysics contributes to fracture detection as well as further description of the crystalline bedrock at the Olkiluoto site. The field surveys were coordinated by geophysical foreman Antero Saukko. Reporting was conducted by Anna-Maria Tarvainen. Geophysical data processing and interpretation and was subcontracted by Pöyry Finland Oy (Eero Heikkinen). Optical and acoustic images were processed and interpreted by Anna-Maria Tarvainen. Data quality control was carried out by Client’s representative (Pöyry Finland Oy). This report describes the field operation of the drillhole surveys and the data processing and interpretation. The quality of the results is shortly analysed and the data presented in the Appendices.

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2 EQUIPMENT AND METHODS

The geophysical surveys carried out in OL-KR54, OL-KR55 and OL-KR55B drillholes included natural gamma radiation, gamma-gamma density, magnetic susceptibility, focused resistivity, fluid temperature and resistivity, caliper and full waveform sonic measurements as well as optical and acoustic imaging. Normal resistivity and single point resistance measurements were substituted with focused resistivity measurements. Old MALÅ GeoScience gamma, density and susceptibility probes as well as new QL40 MagSus magnetic susceptibility probe and Geovista Slimhole density probe were used for natural gamma, density and susceptibility measurements. Acquisition systems and probes are listed in Table 1. Table 1. Acquisition systems and probes.

Method Acquisition Probe Natural gamma Wellmac MALÅ GeoScience Gamma Probe

ALT Matrix Geovista Slimhole Density Sonde Density Wellmac MALÅ GeoScience Density Probe

ALT Matrix Geovista Slimhole Density Sonde Susceptibility Wellmac MALÅ GeoScience Susceptibility Probe

ALT Matrix QL 40 MagSus Focused Resistivity ALT Matrix Geovista Dual Guard Focused Resistivity

Sonde (DLL3) Fluid ALT Matrix Mount Sopris 3-Arm Caliper Sonde Caliper ALT Matrix Mount Sopris Temperature-Fluid Resistivity

sonde Full waveform sonic ALT Matrix ALT FWS 50 Optical imaging ALT Matrix ALT OBI 40 Acoustic imaging ALT Matrix ALT ABI 40

A cable is operated by a motorised winch. Depth measurement is triggered by pulses of a sensitive depth encoder, installed on a pulley wheel. Wellmac measurements applied a 1000 m long 3/16” polyurethane covered 5-conductor cable and all other measurements applied a Mount Sopris manufactured 1000 m long, 3/16” steel reinforced 4-conductor cable. The cables were marked with 10 m intervals for controlling depth measurement to adjust any cable slip and stretch.

2.1 Wellmac Logging System

Wellmac equipment contains gamma, density and susceptibility probes. Gamma probe measures total natural gamma radiation from potassium, uranium and thorium and susceptibility probe the magnetic susceptibility of rock. Density probe uses gamma-gamma density logging method and measures scattered gamma radiation which is converted into density values. Wellmac system consists of a surface unit and a laptop interface as well as a cable winch, a depth measuring wheel and a drillhole probe suite. Each probe is a stand-alone unit and they can be combined as desired. All probes have a diameter of 42 mm. Technical information of Wellmac equipment is presented in Appendix 2.1.

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2.2 Geovista Slimhole Density Sonde

Gamma-gamma density and natural gamma radiation are measured with new integrated Geovista slimhole density sonde. Survey data is obtained from same depth values in a single run. The sonde uses a 10mCi cesium source. The probe measures simultaneously the natural gamma radiation over 134 cm and two gamma-gamma counts over different distances from detector (short spacing density, SSD, 11 cm and long spacing density, LSD, 22 cm). Detectors are 50 x 25 mm NaI crystals. Recording time is 0.22 second. Density probe has a diameter of 38 mm and a length of 1.65 m. Technical information of equipment is presented in Appendix 2.2.

2.3 QL40 MagSus Magnetic Susceptibility Sonde

Magnetic susceptibility is measured with new Bartington’s QL40 MagSus magnetic susceptibility sonde. The sonde has two sections: the focused dual coil detector is located in a non-magnetic enclosure and electronic circuity in an aluminium alloy cylindrical enclosure. The sonde uses operating frequency of 1.5 kHz. The full width half maximum of the vertical magnetic zone of investigation is 120 mm. Susceptibility probe has a diameter of 43 mm and a length of 1.4 m. Technical information of equipment is presented in Appendix 2.3.

2.4 Geovista Dual Guard Focused Resistivity Sonde

Focused resistivity measurement is carried out using Geovista’s Dual Guard (DLL3) focused resistivity sonde. It measures shallow and deep laterolog resistivity and offers deeper penetration and better vertical resolution than the traditional normal resistivity sonde. Current is injected onto a plane perpendicular to drillhole, using two symmetrically placed A-current electrodes at different distances. Return current is arranged on isolator bridle which is 10 m apart of active electrode array. Compensated voltage is measured using closely spaced dipole in the middle of the array. The tool measures the current and the potential. Their ratio is computed and presented as Laterolog shallow and Laterolog deep values which correspond different penetrations of current out of the drillhole. The tool has a diameter of 42 mm and a length of 2.37 m. Technical information of equipment is presented in Appendix 2.4.

2.5 Mount Sopris Caliper and Temperature-Fluid Resistivity Probes

The Mount Sopris manufactured 3-arm caliper sonde and temperature-fluid resistivity sonde are compatible with ALT acquisition system. The caliper arms are attached to a mechanical assembly that drives a linear potentiometer which uses reference voltage and output voltage converted to a frequency. A quadratic correction is used to convert output frequency so that it is linearly related to drillhole diameter. Fluid resistivity is measured by seven electrode mirrored Wenner array and temperature by a semiconductor device. Some of the technical details of the probes are presented in Appendix 2.5.

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2.6 ALT FWS50 Full Waveform Sonic Tool

Full waveform sonic measurement is recorded with Advanced Logic Technology’s (ALT) FWS50 probe which is compatible with Smoy’s ALT acquisition system. A piezoceramic transmitter (Tx) emits sonic impulses of 15 kHz nominal frequency and two receivers (Rx1 and Rx2) detect arriving impulses. The arriving waveform is digitally sampled according to tool configuration parameters. Tx-Rx spacing is 0.6 m (Rx1) and 1.0 m (Rx2). Tool diameter is 50 mm. Technical information of FWS50 equipment is presented in Appendix 2.6.

2.7 ALT OBI40 Slimhole Optical Televiewer

Optical imaging is carried out using Advanced Logic Technology’s (ALT) OBI40 optical televiewer. OBI40 is a high-resolution optical drillhole imagery for wells and drillholes. OBI40 creates a 360 degree image of drillhole wall by using a CCD camera, a prism. Orientation measurement is controlled with a 3-axes magnetometer and 3 accelerometers. This makes possible to measure drillhole deviation data and create accurate orientation of the optical image. OBI40 tool diameter is 40 mm. Tool azimuthal resolution is user definable (90, 180, 360 or 720 pixels per revolution). Vertical resolution depends on sampling rate and maximum resolution is 0.5 mm. Survey rate is 20 – 30 cm/min. Smoy has prepared special centralisers for 76 mm drillholes. Tool technical information of OBI40 equipment is presented in Appendix 2.7.

2.8 ALT ABI40 Slimhole Acoustic televiewer

Acoustic imaging was carried out using Advanced Logic Technology’s (ALT) ABI40 acoustic drillhole televiewer. ABI40 creates a 360 degree image of drillhole wall by using acoustic ultrasound pulses and recordings of amplitude and travel time of signal. Orientation measurement is controlled with a 3-axes magnetometer and 3 accelerometers. This makes possible to measure drillhole deviation data and create accurate orientation of the acoustic image. ABI40 tool diameter is 40 mm. Width of acoustic beam is 1.5 mm. The sampling rate is 72, 144 or 288 measured points per revolution depending on the operator’s selection. Both longitudinal and azimuthal resolution is restricted by width of acoustic beam, i.e. 1.5 mm, although also smaller features can be detected. The detection limit for structures is at order of tens of micrometers. Survey rate is 60 – 100 cm/min. Smoy has prepared special centralisers for 76 mm drillholes. Tool technical information of ABI40 equipment is presented in Appendix 2.8.

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3 FIELD WORK

The field work was carried out within 40 working days between August 2010 and January 2011. The drillhole specifications are listed in Table 2 and the survey parameters of each method in Table 3. The duration of the field work is presented in Appendix 1. Old MALÅ GeoScience gamma, density and susceptibility probes as well as new QL40 MagSus magnetic susceptibility probe and Geovista Slimhole density probe were used for natural gamma, density and susceptibility measurements. Table 4 shows the used natural gamma, density and susceptibility probes for each drillhole.

Table 2. Specifications of the drillholes surveyed.

Drillhole Northing Easting Z Diameter Azimuth Dip Length OL-KR54 6792477.68 1527226.91 2.62 76 mm 191.1 70.5 500.18 OL-KR55 6792485.97 1527218.52 2.55 76 mm 279.9 59.3 998.40 OL-KR55B 6792481.75 1527222.67 2.57 76 mm 221.7 68.9 44.99

Table 3. Survey parameters of the applied methods.

Method Depth sampling Settings Survey speed

Natural gamma/ Wellmac 0.02 m Calibrated for rapakivi granite in 1999 2.0 m/min

Natural gamma/ Geovista 0.02 m Compared to reading of Wellmac tool 2.0 m/min

Density/ Wellmac 0.02 m Calibrated for KR19-KR22 in 2001 and

Olkiluoto site specific histogram fitting 2.0 m/min

Density/ Geovista 0.02 m Calibrated with site petrophysical density

and readings of Wellmac tool 2.0 m/min

Susceptibility/ Wellmac 0.02 m Calibration with brick and Olkiluoto site

specific histogram fitting 2.0 m/min

Susceptibility/ QL40 MagSus 0.02 m Adjusted to site petrophysical level 2.0 m/min

DLL3 0.02 m Calibrated with measuring the resistance of known calibration pad 2.5 m/min

Caliper 0.01 m Calibrated with rings 1.0 m/min

Fluid resistivity and temperature 0.05 m

Calibrated for temperature using Pt-1000 thermometer, and for fluid resistivity with known NaCl solutions and temperature

3.0 m/min

Full waveform sonic 0.02 m Time sampling 2 μs, time Interval 0…2048

μs R1 gain 1, R2 gain 1 1.0 m/min

Optical imaging 0.0005m 720 pixels / turn, 0.5 mm depth interval 0.3 m/min

Acoustic imaging 0.0014 m 288 measured points per revolution, 1.5 mm depth interval 0.8 m/min

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Table 4. Used natural gamma, density and susceptibility probes for each drillhole..

OL-KR54 OL-KR55 OL-KR55B Natural gamma/Wellmac x x Natural gamma/Geovista x x x Density/Wellmac x x Density/Geovista x x x Susceptibility/Wellmac x x x Susceptibility/QL40 MagSus x

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4 PROCESSING AND RESULTS

The processing of the conventional geophysical results includes basic corrections and calibrations presented in Posiva Working report 2001-30 (Lahti et al. 2001). Sonic interpretations, depth adjustments and data integration were carried out by Pöyry Finland Oy (Eero Heikkinen) as described in Heikkinen et al. (2005). Optical and acoustic images were processed by Anna-Maria Tarvainen. Natural gamma radiation, gamma-gamma density, magnetic susceptibility, caliper, fluid temperature and resistivity as well as shallow and deep laterolog resistivity results are presented in Appendix 2.1.1, 2.2.1 and 2.3.1. Derived fluid properties are separately displayed in Appendices 2.1.2, 2.2.2 and 2.3.2. The full waveform sonic results are shown in Appendices 2.1.3, 2.1.4, 2.2.3, 2.2.4, 2.3.3 and 2.3.4. Acoustic images are presented in Appendices 2.1.5 and 2.2.5. An example of the optical image is shown in Appendix 2.1.6. The results were joined with the available geological data received from Posiva. The data includes lithology, fracture frequency, fracture location and core loss. The initial depth matching is based on cable mark control. The locations of rock type contacts and fractures in core were used in the final depth matching. At first drillhole optical and acoustic images were adjusted to core data. Gamma-gamma density and natural gamma was set to the image depth using mafic gneiss variants and leucosome parts. Susceptibility and sonic data were adjusted according to density. Electrical measurements were adjusted according to sonic and density minima and susceptibility maxima (conductive zones). Depth accuracy to core depth of all methods is better than 5 cm. The fluid resistivity results were set only according to cable marks, allowing accuracy of 10-30 cm.

4.1 Natural gamma radiation

Wellmac raw data is converted into μR/h values using a coefficient determined at drillholes HH-KR5 and HH-KR8 in Hästholmen, Loviisa. The conversion is carried out so that 1 μR/h equals 3.267 p/s. The determination of the coefficient is presented in Posiva’s Working report 99-22 (Laurila et al. 1999). The results are presented in Appendix 1.1.1, 1.2.1 and 1.3.1. The new Geovista probe was calibrated by comparing the readings to reading of Wellmac tool. The same numeric level in microRontgen/hr is obtained by multiplying the count provided by Geovista probe by factor 1.8. Natural gamma counts are enhanced by larger NaI crystal but reduced by shorter counting time which makes the gamma ray values slightly noisier compared to those of Wellmac tool. The results measured with new Geovista sonde are presented in Appendix 2.2.1, 2.2.1 and 2.3.1.

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Table 5. Results of the natural gamma radiation survey. Tool: Geovista Slimhole Density Sonde.

Drillhole Depth interval (m) Range (μR/h) min max min max median

OL-KR54 38.01 497.11 1.70 118 38.5 OL-KR55 38.00 981.68 5.41 310 37.8 OL-KR55B 0.31 43.55 5.33 73.5 34.7

4.2 Gamma-gamma density

The calibration of Wellmac density values is carried out using the calibration conducted during surveys of drillholes OL-KR19, OL-KR20 and OL-KR22 and the petrophysical samples taken from those drillholes (Lahti et al. 2003). The accuracy of the density data is better than 0.01 g/cm3. The level of the data was checked on a basis of the petrophysical data distribution from the site (not from the same drillholes, though). The levels of both magnetic susceptibility and density would be more reliably calibrated with petrophysical sample data from the drillhole surveyed. The activity of the new Cs-137 source and the new geometry of Geovista probe were calibrated with petrophysical density distribution of the site (Aaltonen et al. 2009) and comparison between previous Wellmac survey, run overlapping in drillholes OL-KR54 and OL-KR55. Counts recorded by tool are first converted to counts per second. Calibration to density was deduced with curve fitting to a 3rd order function at range 1.1 - 3.5 g/cm3. Calibration is valid for water filled 76 mm drillhole diameter. For other diameter and dry hole conditions the calibration has to be considered separately. The decay of the source (Cs-137 half-life 30.17 years) will reduce the count (increase apparently the density) which has to be taken into account frequently. The results measured with new Geovista sonde are presented in Appendix 2.2.1, 2.2.1 and 2.3.1.

Table 6. Results of the gamma-gamma density survey. Tool: Geovista Slimhole Density Sonde. Drillhole Depth interval (m) Range (g/cm3)

min max min max median OL-KR54 38.03 498.35 2.23 3.43 2.72 OL-KR55 38.00 981.68 2.36 3.17 2.71 OL-KR55B 1.51 44.77 2.34 3.72 2.73

4.3 Magnetic susceptibility

The susceptibility probe was calibrated using a calibration brick with known susceptibility of 740×10-5 SI and a value taken in free air, both before and after the logging run. Temperature drift was compensated on a basis of visual examination. Reading accuracy is 1-2 ×10-5 SI. The level of the data was checked on a basis of

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petrophysical data distribution from the site (not from the same drillholes, though). Reason for occasional negative results is probably diamagnetic graphite or quartz in rock mass. Susceptibility measurement with QL40 MagSus probe was imported without tool calibration. Simultaneously measured temperature was used to remove temperature drift. Drift was defined by analysis of temperature dependency. After removal the values were adjusted to site petrophysical level by removing level difference (883) so that the pegmatite granite values are close to zero. The cgs units were converted to SI values by multiplication by 4� and experimental factors, using c. 16.5. Level and distribution was checked against site petrophysical distribution. The results measured with MALÅ GeoScience Susceptibility Probe are presented in Appendices 2.2.1, 2.2.1 and 2.3.1. The results with QL40 MagSus probe need further consideration because of calibration issues.

Table 7. Results of the susceptibility survey. Tool: MALÅ GeoScience Susceptibility Probe. Drillhole Depth interval (m) Range (E-5 SI)

min max min max median OL-KR54 38.65 499.37 -36719 22859 28.8 OL-KR55 38.00 982.12 -38503 887 31.6 OL-KR55B 11.33 43.91 0.52 21706 2084

4.4 Focused resistivity

Tool resistivity reading was calibrated with measuring the resistance of known calibration pad at 1 Ohm, 10 Ohm, 100 Ohm and 1000 Ohm. Calibration was carried out by fitting a 3rd order function on the logarithmic observation values. Raw results are imported without calibration, and then computed to resistivity values using the deduced function. Measurement range is wide from < 0.1 Ohm metre to over 60.000 Ohm metre. The tool does not require compensation for drillhole fluid resistivity or drillhole diameter. Resistivity data has been depth corrected using location of fractures in the core log and image, and with susceptibility data where some of magnetized layers are also conductive. The results are presented in Appendices 2.2.1, 2.2.1 and 2.3.1.

Table 8. Results of shallow dual laterolog resistivity.

Drillhole Depth interval (m) Range (Ohm metre) min max min max median

OL-KR54 36.01 500.33 1.06 23191 5602 OL-KR55 38.00 994.82 5.88 25251 9888 OL-KR55B 11.33 44.77 -52691 15670 15.7

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Table 9. Results of deep dual laterolog resistivity.

Drillhole Depth interval (m) Range (Ohm metre) min max min max median

OL-KR54 36.01 500.33 1.27 24731 7068 OL-KR55 38.00 994.82 2.64 26494 10448 OL-KR55B 11.33 43.91 0.46 22265 2011

4.5 Fluid temperature and resistivity

The fluid temperature was calibrated using Pt-1000 electronic thermometer over the measurable range in Olkiluoto drillholes, 5 – 20 ºC. The accuracy of the temperature recording is 0.01 ºC. Since the tool response of resistivity is linear only for resistive fluids, a non-linear (2nd order) calibration function was deduced. The fluid resistivity was calibrated using solutions of known NaCl-concentration, and electrical conductivity (EC) from literature (Table 9; Eutech Instruments 2005) for temperature of 25 ºC. Literature values were used since it is known that actual measurement of EC is strongly frequency dependent, and would require increasingly high frequencies to avoid saturation when the concentration increases (Radiometer Analytical 2005). The theoretical EC values in 25 ºC were converted to measurement temperature T of the NaCl-solution samples using conversion relation presented in Poikonen (1983).

Table 10. Concentrations, resistivity and pulse counts of prepared synthetic solutions. Concent-ration g/l

Resistivity in 25 ºC [Ohm metre]

Temperature T [ ºC]

Resistivity in T [Ohm metre]

Pulses

0.5 9.736517 13.61 - 13.78 10.626 – 10.677 28409 - 28412 2 2.559817 18.25 - 20.0023 2.536 – 2.644 30920 - 30925 10 0.523553 18.1717 - 18.3088 0.5900-0.5920 31520 - 31525 33 0.185773 15 -15.1371 0.2756 – 0.27668 31626 - 31658 64 0.104223 17.4473 - 17.6235 0.172364 - 0.17312 31656 - 31659 90 0.078728 14.119 - 14.1777 0.11894 – 0.11913 31663 - 31668

A function was deduced to convert the obtained data in pulses (range 0….32000) to actual fluid resistivity values. The data values were then converted both to resistivity in temperature of 25 ºC, and to apparent Total Dissolved Solids (TDS, g/l) values according to Heikkonen et al. (2002). Measurement is rather insensitive at high salinity values 60-100 g/l (0.07 – 0.1 �m), where also electromagnetic noise of the site has a large influence. Noise can be caused from small particles present in the fluid, too. Reading accuracy of fluid resistivity recording is 0.008 �m at the whole measurement range (0.05…approx. 200 �m). The results are presented in Appendices 2.1.2, 2.2.2 and 2.3.2.

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Table 11. Results of processed fluid temperature data.

Drillhole

Depth interval (m) Range (°C) min max min max median

OL-KR54 1.24 495.42 6.48 11.8 8.8 OL-KR55 1.19 987.11 6.46 16.6 11.1 OL-KR55B 0.80 44.78 6.16 11.0 6.2

Table 12. Results of processed fluid resistivity data.

Drillhole

Depth interval (m) Range in 25 °C (Ohm m) min max min max median

OL-KR54 1.34 495.48 2.22 29.1 2.92 OL-KR55 1.19 987.17 1.90 185.4 4.00 OL-KR55B 2.44 44.86 2.7378 58.4 8.14

4.6 Caliper

The caliper measurement has been calibrated using a set of tubes with known diameter for each length of arms. The diameter has been measured both before and after logging to compensate wearing in the hard metal tips of arms, and possible changes in level. Measurement was performed with a single arm connected, which provides highest location accuracy. The accuracy of caliper reading is 0.04 mm. Range of relevant readings is 74...96 mm for a single short arm in a 75.7 mm drillhole. Small, positive or negative values of caliper indicate errors in reading or communication. The results are presented in Appendices 2.2.1, 2.2.1 and 2.3.1.

Table 13. Results of processed caliper data.

Drillhole

Depth interval (m) Range (mm) min max min max median

OL-KR54 36.01 496.70 74.6 92.1 76.1 OL-KR55 38.34 868.72 38.0 90.9 76.0 OL-KR55B 0.31 44.52 74.8 89.9 76.1

4.7 Full Waveform Sonic

The sonic data processing has followed the outlines defined in reports by Lahti & Heikkinen (2004 and 2005) and Öhman et al. (2009) for the FWS50 tool. The processing consisted of visual inspection of the recording and defining P and S wave velocities and tube wave energies for both channels, and their attenuations. Raw data was read in WellCAD (ALT 2001) and exported to SEG-2 format to be processed in ReflexW (2003). Traces were resampled to 0.1 microsecond and filtered with 3-8 and 33-38 kHz band-pass. A phase follower was applied to pick the appropriate distinct P and S wave coherently. A semiautomatic process was continued if the automatic picking failed. Convenient multiple of a half cycle (wave length time,

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typically 20-24 μs for this dataset) was subtracted from the most distinct cycle time (first maximum and minimum for S and P, respectively). True velocity was computed using stand-off correction. The correct level of velocity was checked against the distribution of petrophysical velocity values from the site (Öhman et al. 2009, Aaltonen et al. 2009). The data processing included the computation of P and S wave attenuations, reflected tubewave energies and finally the attenuation of tubewaves. Also dynamic rock mechanical parameters, Young’s modulus Edyn, Shear modulus μdyn, Poisson’s ratio �dyn, Bulk modulus and apparent Q’ value (Barton 2002) were computed from the acoustic and density data. All the acoustic data and derived parameters are displayed in Appendices 2.1.3, 2.1.4., 2.2.3, 2.2.4, 2.3.3 and 2.3.4.

Table 14. Results of the full waveform sonic survey, OL-KR54.

Drillhole: OL-KR54

Depth interval (m) Range min max min max median

Velocity P 0.6m (m/s) 2.66 5752.46 2931 7502 5717 Velocity P 1.0 m (m/s) 2.66 5752.46 2620 7063 5742 Velocity S 0.6 m (m/s) 2.64 498.24 1843 4081 3251 Velocity S 1.0 m (m/s) 2.66 5752.46 -12011 3876 3217 Attenuation P (dB/m) 2.66 5752.46 -86.9 50.0 -10.7 Attenuation S (dB/m) 2.66 5752.46 -100.4 111.8 4.3 Tubewave amplitude 0.6 m (μV) 2.66 5752.46 6197 948368 187461 Tubewave amplitude 1.0 m (μV) 2.66 5752.46 6936 2069560 144414 Tubewave attenuation (dB/m) 2.68 5752.46 -27.9 26.5 -5.5 Poisson’s Ratio 2.64 498.24 -0.50 0.39 0.26 Shear Modulus (GPa) 38.02 498.24 9.27 50.4 28.9 Young’s Modulus (GPa) 38.02 498.24 18.0 123.7 72.8 Bulk Modulus (GPa) 38.02 498.24 3.2 109.4 50.4 Bulk Comp 1/Mpa 38.02 498.24 0.0091 0.31 0.020 Apparent Q 2.64 498.42 0.27 10043 164.9

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Table 15. Results of the full waveform sonic survey, OL-KR55.

Drillhole: OL-KR55


Velocity P 0.6m (m/s) 2.13 985.29 3060 6497 5684 Velocity P 1.0 m (m/s) 2.13 985.29 3286 6563 5716 Velocity S 0.6 m (m/s) 2.13 985.29 -7057 3908 3260 Velocity S 1.0 m (m/s) 2.13 985.29 1796 3752 3218 Attenuation P (dB/m) 2.13 985.27 -91.9 67.1 -1.32 Attenuation S (dB/m) 2.09 985.29 -123.9 50.0 -14.9 Tubewave amplitude 0.6 m (μV) 2.11 985.31 2879 1019990 217032 Tubewave amplitude 1.0 m (μV) 2.11 985.31 2960 1373410 159777 Tubewave attenuation (dB/m) 2.11 985.31 -38.3 22.8 -6.5 Poisson’s Ratio 2.11 985.15 0.03 0.39 0.26 Shear Modulus (GPa) 2.13 981.67 7.01 44.0 28.7 Young’s Modulus (GPa) 2.13 981.67 18.3 108.8 72.2 Bulk Modulus (GPa) 2.13 981.67 10.2 77.6 49.0 Bulk Comp 1/Mpa 2.13 981.67 0.013 0.10 0.020 Apparent Q 2.11 985.31 0.36 994 152.8

Table 16. Results of the full waveform sonic survey, OL-KR55B.

Drillhole: OL-KR55


Velocity P 0.6m (m/s) 2.19 43.97 2745 6001 5212 Velocity P 1.0 m (m/s) 2.19 43.97 3238 5893 5280 Velocity S 0.6 m (m/s) 2.19 43.97 1719 2992 2700 Velocity S 1.0 m (m/s) 1.69 43.47 2012 3016 2713 Attenuation P (dB/m) 2.19 43.97 -150.1 38.9 -4.8 Attenuation S (dB/m) 2.19 43.97 -93.5 49.7 -12.4 Tubewave amplitude 0.6 m (μV) 2.21 43.97 104247 936089 734114 Tubewave amplitude 1.0 m (μV) 2.21 43.97 256505 1262450 976989 Tubewave attenuation (dB/m) 2.23 43.97 -2.3 25.8 7.6 Poisson’s Ratio 2.19 43.97 0.075 0.41 0.32 Shear Modulus (GPa) 2.19 43.97 7.04 24.1 21.3 Young’s Modulus (GPa) 2.19 43.97 17.0 64.1 55.2 Bulk Modulus (GPa) 2.19 43.97 8.5 75.2 48.1 Bulk Comp 1/Mpa 2.19 43.97 0.013 0.12 0.021 Apparent Q 2.19 43.97 0.18 317 52.1

4.8 Optical drillhole image

The applied survey parameters of drillhole imaging were determined according to earlier optical televiewer works at the Olkiluoto site (Lahti 2004a, Lahti 2004b). The survey was never left unsupervised. The overlapping of data between recorded intervals was ensured by rerunning of the last 0.5 m of each recording. The data processing carried out after the field work consists of the depth adjustment and the image orientation of the raw image. The methods are presented in the Posiva

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Working report 2004-27 by Lahti (2004a). The images were produced to depth matched and oriented to high side presentations including a 3D image. Images can be viewed using WellCAD Reader and WellCAD software. For the report, the images were also printed on PDF documents in scale 1:4. In the original logging optical image was missing from 511.2–520.1 m depth from drillhole OL-KR55 because of the surveyor's mistake when counting the cable marks. The missing part of the image was measured separately in July 2011, and the results have been saved to Potti and Kronodoc systems. An example of optical image is presented in Appendix 2.1.6.

Table 17. Depth interval of optical drillhole imaging.

Drillhole Depth interval (m) min max OL-KR54 38.72 498.30 OL-KR55 38.69 984.70 OL-KR55B 12.82 44.86

4.9 Acoustic drillhole image

The applied survey parameters of drillhole imaging were determined according to working report 2009-41 (Tiensuu & Heikkinen 2009). The data processing of the drillholes included depth matching and image correction. The quality of the data was controlled during the survey. The survey was never left unsupervised. The overlapping of data between recorded intervals was ensured by rerunning of the last 0.5 m of each recording. The results are presented as amplitude variation and centralised travel time as well as variation in the drillhole caliper (minimum, maximum and average). The amplitude image is also presented as exaggerated 3-D view, using non-centralised travel time as caliper. Images can be reviewed with WellCAD Reader and WellCAD software. For the report, the images were also printed on PDF documents, in scale 1:200. The acoustic image is presented in Appendix 2.1.5 and 2.2.5.

Table 18. Depth interval of acoustic drillhole imaging.

Drillhole Depth interval (m) min max OL-KR54 39.35 498.38 OL-KR55 38.65 984.77

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5 COMPARISON OF RESISTIVITY, SUSCEPTIBILITY, NATURAL GAMMA AND DENSITY MEASUREMENTS WITH NEW AND OLD PROBES

Resistivity, susceptibility, natural gamma and density measurements were carried out with new and old probes. Normal resistivity and single point resistance measurements were substituted with focused resistivity measurements carried out with Geovista’s Dual Guard (DLL3) sonde. Old MALÅ GeoScience gamma, density and susceptibility probes as well as new QL40 MagSus magnetic susceptibility probe and Geovista Slimhole density probe were used for natural gamma, density and susceptibility measurements.

5.1 Resistivity measurements

The data of drillhole ONK-KR13 was available for the comparison of single point resistance, short normal and long normal (Elog) to Dual Laterolog-3 shallow and deep (DLL3). The data is presented in Figure 1 which shows lithology, fractures and caliper, short and long normal resistivity, fluid resistivity, fluid corrected short and long normal resistivities and DLL3 results from left to right. Dual laterolog tool has significantly better spatial resolution which indicates responses from even narrow resistive or conductive layers (fractures etc). DLL3 results are readily representing true, petrophysical in situ resistivity of the rock mass. Fluid corrected short and long normal resistivity and DLL3 levels are similar. DLL3 does not need fluid compensation. Difference on the shallow and deep results describes the resistivity difference of drillhole water compared to bedrock groundwater. This ratio can be used to deduce resistivity of bedrock groundwater when drillhole fluid resistivity is known, and further to deduce the formation factor from fluid and rock mass resistivity.

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Figure 1. Comparison of single point resistance, short normal and long normal (Elog) to Dual Laterolog-3 shallow and deep (DLL3) results in drillhole ONK-KR13. From left to right: lithology, fractures and caliper, SN and LN, fluid resistivity, fluid corrected SN and LN as well as DLL3 results.

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5.2 Susceptibility measurements

The comparison of susceptibility data is made from drillhole ONK-KR54 and is presented in Figure 2. Wellmac data is presented with green and QL40 MagSus data with blue on left. Detail at 300-350 m from drillhole OL-KR54 is presented on right above and an example Geovista susceptibility probe temperature calibration on right below. Data has been depth adjusted to core, converted to physical values, temperature adjusted and level checked to petrophysical data distribution. Geovista tool has higher noise on low susceptibility due to sensitivity setting in the probe. Spatial resolution of magnetic units is better with Geovista tool. The results with QL40 MagSus probe need further consideration because of calibration issues.

Figure 2. Comparison of susceptibility data measured with Wellmac (Malå Geoscience) and QL40 MagSus probes. Detail at 300-350 m from drillhole OL-KR54 is presented on right above and an example Geovista susceptibility probe temperature calibration on right below.

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5.3 Natural gamma and density measurements

Natural gamma and density measurements were made with Wellmac density probe and Geovista Slimhole density probe. The comparison of natural gamma data and density data is presented in Figures 3 and 5. Figure 3 shows depth adjusted natural gamma data (green: Wellmac, blue: Geovista) from OL-KR54 on left. Detail at 300-350 m is presented on right above. Geovista tool has higher noise level due to short 0.2 s integration time. Stacking would improve result but it is more useful to measure density and gamma simultaneously. Longest distance of gamma sensor is not affected by Cs-137 source in simultaneous measurement. The measurement without Cs-137 source was carried out in OL-KR55B. Comparison of natural gamma results is presented with three different and stacked data on right below and stacked data on right below, Figure 4. Profiles are identical except random variation.

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Figure 3. Comparison of natural gamma data measured with Wellmac (Malå Geoscience) and Geovista slimhole density probe in drillholes OL-KR54 (left and right above) and OL-KR55B (right below). Left: depth adjusted natural gamma (green: WellMAC, blue: Geovista) from OL-KR54; right above: detail at 300-350 m, and right below: comparison of natural gamma results from OL-KR55B with three different sensors in Geovista probe without Cs-137 source (profiles are identical except random variation) and stacked data.

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Figure 5 shows depth adjusted density data (green: Wellmac, blue: Geovista) and from OL-KR54 on left and a detail at 300-350 m on right. Geovista tool specifications differing from previous Wellmac affect the results. Higher count rate of fresh source, larger crystal and shorter spacing are increasing the nominal accuracy of readings. Geovista tool has significantly better spatial resolution due to short 11 cm spacing which also enhances the resolution of thin layers and fractures. Some advantages of high count rate and large crystal are lost by shorter 0.2 s counting time which increases noise level. Geovista density data is very similar to previous Wellmac data, with higher level of detail but containing slightly more noise which may be both temporal and spatial. Long spaced density has deeper radius of investigation, and it averages the rock mass properties more. Because core drilling in crystalline rock produces very smooth drillhole wall, the short spacing density applies well for accurate density measurement of rock mass. Wellmac density seems to have included minor depth (temperature) dependency which is not present in results of Geovista tool. The dependency is presented in Figure 4.

Figure 4. The depth dependency of density measured with Wellmac.

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Figure 5. Comparison of density data measured with Wellmac (Malå Geoscience, green) and Geovista slimhole density (blue) from OL-KR54. Left: whole of drillhole, right: detail at 300 – 350 m.

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6 CONCLUSIONS

The task of surveying OL-KR54, OL-KR55 and OL-KR55B drillholes was concluded between August 2010 and January 2011. A missing part of the optical image of OL-KR55 was surveyed in July 2011. New focused resistivity, susceptibility, natural gamma and density probes were tested and compared with old probes. The processed and interpreted data was delivered to the Client in digital format. The draft report was compiled in May 2011. The quality was observed and validated by Pöyry Finland Oy (Eero Heikkinen).

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REFERENCES

Aaltonen, I., Heikkinen, E., Paulamäki, S., Säävuori, H., Vuoriainen, S. & Öhman, I. 2009. Summary of petrophysical analysis of Olkiluoto core samples 1990 – 2008. Posiva Working Report 2009-11, 235 p. ALT 2001. WellCAD user’s guide for version 3.0. Advanced Logic Technologies, Luxembourg. 831 p. Barton, N. 2002. Some new Q-value correlations to assist in site characterization and tunnel design. International Journal of Rock Mechanics & Mining Sciences 39 (2002), 185-216. Heikkinen, E., Tammisto, E., Ahokas, H., Lahti, M. & Ahokas., T. 2005. Geophysics applied in tunnel pilot boreholes for pre-grouting design parameters. Extended abstract A045, 11th European meeting of Environmental and Engineering Geophysics, 4th - 7th September 2005, Palermo, Italy Lahti, M., Tammenmaa J. ja Hassinen P. 2001. Kairanreikien OL-KR13 ja OL-KR14 geofysikaaliset reikämittaukset Eurajoen Olkiluodossa vuonna 2001 (Geophysical borehole logging of the boreholes OL-KR13 and OL-KR14 in Olkiluoto, Eurajoki, 2001). Työraportti 2001-30. Posiva Oy, 136 p. Lahti, M., Tammenmaa, J. & Hassinen, P. 2003. Geophysical logging of boreholes OL-KR19, OL-KR19b, OL-K20, OL-KR20b, OL-KR22, OL-KR22b and OL-KR8 continuation at Olkiluoto, Eurajoki 2002. Posiva Oy. 176 p. Working report 2003-05. Lahti, M. 2004a. Digital borehole imaging of the boreholes KR6, KR8 continuation, KR19, KR19b, KR20, KR20b, KR21, KR22, KR22b, KR23, KR23b and KR24 at Olkiluoto during autumn 2003. Posiva Oy. Working report 2004-27. 39 p. Lahti, M 2004b. Digital borehole imaging of the boreholes KR24 upper part and PH1 at Olkiluoto, March 2004. Posiva Oy. Working report 2004-28. 21 p. Lahti, M & Heikkinen, E. 2004. Geophysical borehole logging of the borehole PH1 in Olkiluoto, Eurajoki 2004. Posiva Oy. Working report 2004-43. 30 p. Lahti, M & Heikkinen, E. 2005. Geophysical borehole logging and optical imaging of the pilot hole ONK-PH2. Posiva Oy. Working report 2005-04. 72 p Laurila, T. Tammenmaa J. ja Hassinen P. 1999. Kairareikien HH-KR7 ja HH-KR8 geofysikaaliset reikämittaukset Loviisan Hästholmenilla vuonna 1999 (Geophysical borehole logging of the boreholes HH_KR7 and HH-KR8 at Hästholmen, Loviisa, 1999). Posiva Oy, Työraportti 99-22. ReflexW. 2003. Version 3.0. Karlsruhe, Germany. K-J. Sandmeier. 341 p.

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Saksa, P., Hellä, P., Lehtimäki, T., Heikkinen, E. & Karanko, A. 2001. Reikätutkan toimivuusselvitys (On the performance of borehole radar method). Posiva, Working Report 2001-35, 134 p. Tiensuu, K. and Heikkinen, E. 2009. Acoustic imaging of the drillholes OL-KR19, OL-KR40, OL-KR46 and OL-KR46B, at Olkiluoto 2008. Working report 2009-41. Posiva Oy, Eurajoki. 22 p. Öhman, I., Palmén, J. & Heikkinen, E. 2009. Unification of acoustic drillhole logging data. Posiva, Working Report 2009-32, 64 p.

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Appendix 1: Timing of the field work August 2010 Date Drillhole Actions Surveyors 30.8. OL-KR55 Optical imaging HL 31.8. OL-KR55 Optical imaging HL, PT, AKu September 2010 Date Drillhole Actions Surveyors 1.9. OL-KR55 Acoustic imaging HL, PT, AKu 2.9. OL-KR55 Acoustic imaging HL, AKu 6.9. OL-KR55 Acoustic imaging HL, AKu 7.9. OL-KR55 Fluid resistivity & temperature survey HL, PT, AKu8.9. OL-KR55 Full waveform sonic survey HL, PT, AKu9.9. OL-KR55 Caliper survey HL, PT, AKu 14.9. OL-KR55 Caliper survey HL 15.9. OL-KR55 Natural gamma survey HL, AS 16.9. OL-KR55 Natural gamma survey HL, AS 20.9. OL-KR54 Optical imaging HL, AS, AKi 21.9. OL-KR54 Optical imaging AS 22.9. OL-KR54 Optical imaging, Full waveform sonic survey AS 23.9. OL-KR54 Full waveform sonic survey AS 24.9. OL-KR54 Natural gamma survey HL, AS 27.9. OL-KR54 Density survey, Susceptibility survey HL, AS 28.9. OL-KR54 Susceptibility survey, Natural gamma survey AKi, AS 29.9. OL-KR54 Density survey AS 29.9. OL-KR55B Optical imaging, Fluid resistivity & temperature

survey, Full waveform sonic survey AS

30.9. OL-KR55B Caliper survey, Susceptibility survey AS

October 2010 Date Drillhole Actions Surveyors 7.10. OL-KR55B Density survey, Natural gamma survey EN, JV, AS 8.10. OL-KR55 Density survey EN, JV 9.10. OL-KR55 Susceptibility survey EN, JV 10.10. OL-KR54 Density survey EN, JV 11.10. OL-KR54 Caliper survey EN, JV, AS12.10. OL-KR54 Fluid resistivity & temperature survey EN, JV, AS

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November 2010 Date Drillhole Actions Surveyors 1.11. OL-KR54 Dual Laterolog survey HL 4.11. OL-KR54 Dual Laterolog survey HL 9.11. OL-KR55 Optical imaging JV 10.11. OL-KR55 Optical imaging JV 12.11. OL-KR55 Optical imaging JV 13.11. OL-KR54 Acoustic imaging JV 14.11. OL-KR54 Acoustic imaging JV 16.11. OL-KR55 Dual Laterolog survey JV 30.11. OL-KR55B Dual Laterolog survey JV

’ January 2011 Date Drillhole Actions Surveyors 18.1. OL-KR55 Optical imaging PT, AK 20.1. OL-KR55 Optical imaging PT, AK 21.1. OL-KR55 Optical imaging PT, AK 22.1. OL-KR55 Optical imaging PT, AK

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Appendix 2: Results The legend of lithological data

geophysical drillhole logging and imaging of drillholes ol ......suomen malmi oy conducted...

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