MINNOVA INC. GEOPHYSICAL REPORT ON AN BOREHOLE PULSE EM SURVEY

MT. SICKER PROPERTY, HOLES MTS-53, MTS-54, MTS-55, AND MTS-57

LATITUDE: 48° 52'N LONGITUDE: 123° 47' NTS: 92B/11E

AUTHOR: DENNIS V. WOODS, Ph.D.,P.Eng. Geophysicist

DATE OF WORK: 8-10 June 1988 DATE OF REPORT: 16 J u l y 1988

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W H I T E G E O P H Y S I C A L I N C .

TABLE OF CONTENTS PAGE

INTRODUCTION 1 PROPERTY LOCATION AND ACCESS 1 BOREHOLE PULSE EM TECHNIQUE 1-3 SURVEY PROCEDURE 3 DISCUSSION OF RESULTS 4 CONCLUSIONS AND RECOMMENDATIONS 4-5 REFERENCES 6 INSTRUMENT SPECIFICATIONS 7-8 STATEMENT OF QUALIFICATIONS

Dennis V. Woods, Ph.D., P.Eng 9

ILLUSTRATIONS

Figure 1 Borehole L o c a t i o n Map Figures 2-5 Borehole Pulse EM P r o f i l e s

W H I T E G E O P H Y S I C A L I N C .

INTRODUCTION:

On 8-10 June 1988, a borehole Pulse EM survey was c a r r i e d out on Minnova Inc. boreholes MTS-53, MTS-54, MTS-55 and MTS-57 on the Mt. Sicker property, Vancouver I s l a n d .

The purpose of the survey was to explore f o r p o s s i b l e zones of conductive sulphide m i n e r a l i z a t i o n i n the v i c i n i t y of the d r i l l h o l e s , not n e c e s s a r i l y i n t e r s e c t e d by the holes.

PROPERTY LOCATION AND ACCESS:

The Mt. Sicker property i s l o c a t e d about 10 km northeast of Duncan, B.C. on Vancouver I s l a n d . Access i s v i a logging roads o f f the Lake Cowichan highway 1.5 km east of the Trans Canada highway.

BOREHOLE PULSE EM TECHNIQUE

The Crone borehole pulse EM system i s a time domain downhole EM instrument capable of d e t e c t i n g conductive m i n e r a l i z a t i o n i n t e r s e c t e d by the d r i l l h o l e or l y i n g o f f h o l e . The borehole pulse EM system u t i l i z e s a s p e c i a l downhole r e c e i v e r c o i l , 600m cable and winch i n conjunction w i t h a standard PEM t r a n s m i t t e r and re c e i v e r normally employed i n surface surveys.

The primary f i e l d i s produced by a 150m by 150m square surface loop d r i v e n by the 500 watt PEM t r a n s m i t t e r . Large loop surveys (e.g. 500m by 1000m) using the 2000 watt t r a n s m i t t e r , and sm a l l loop surveys using the 10m diameter portable equipment, can be c a r r i e d out depending on the depth and s i z e of the expected conductive t a r g e t .

The time d e r i v a t i v e of the secondary EM f i e l d i s measured using an a x i a l r e c e i v e r c o i l lowered down the diamond d r i l l h o l e . The minimum s i z e of d r i l l h o l e which can be accommodated i s AQ (1 3/4"

W H I T E G E O P H Y S I C A L I N C .

diameter). The r e c e i v e r obtains e i g h t samples of the secondary f i e l d during the primary f i e l d o f f - t i m e . Sample times range from 0.15 to 6.4 ms a f t e r primary f i e l d s h u t - o ff on a 10.8 ms t r a n s m i t t e r time base.

M u l t i p l e t r a n s m i t t e r loops may be used to provide various loop to conductor c o u p l i n g geometries i n order to o b t a i n conductor a t t i t u d e and p o s i t i o n i n f o r m a t i o n . A complete survey of a given borehole may e n t a i l logging the hole from f i v e t r a n s m i t t e r loop setups. One of these loops would be approximately centred over the area of i n t e r e s t w i t h the remaining four loops away from and d i s t r i b u t e d around the borehole.

When an anomalous response i s observed i n a borehole l o g from a s i n g l e t r a n s m i t t e r loop, the nature of t h i s anomaly allows the determination of the l o c a t i o n of the conductive source r e l a t i v e to the d r i l l h o l e . As shown by Woods and Crone (1980, F i g s . 7 & 8), the response can i n d i c a t e whether the borehole i s i n t e r s e c t i n g the centre of the conductor, the margin of a conductor, w i t h the bulk of conductive m a t e r i a l away from the ho l e , or whether the conductor i s e n t i r e l y o f f - h o l e .

Model study curves f o r various conductor to borehole geometries from Woods (1975) are employed i n the i n t e r p r e t a t i o n . Q u a n t i t a t i v e a n a l y s i s of the conductor's a t t i t u d e , p o s i t i o n and conductance i s made us i n g nomograms presented by Woods, et a l . (1980). Computer p l a t e modelling, using the r o u t i n e s developed by Dyck, et a l (1980), can be used t o confirm the i n t e r p r e t a t i o n .

In the case of a d i k e - l i k e or t a b u l a r conductor, the magnitude of an anomaly v a r i e s w i t h the angle t h a t the primary f i e l d cuts the conductor. Thus, the degree to which c o u p l i n g i s obtained to the conductor, i n coverage of a borehole from s e v e r a l loop setups, w i l l provide i n f o r m a t i o n on the a t t i t u d e and p o s i t i o n of the conductive m i n e r a l i z a t i o n .

W H I T E G E O P H Y S I C A L I N C .

I f the conductor tends towards a more s p h e r o i d a l shape, the anomaly character w i l l change, as w e l l as i t s magnitude, when the primary f i e l d angle i s a l t e r e d . This occurs because the eddy cur r e n t s are not co n s t r a i n e d to flow w i t h i n a conductive sheet. Thus, m u l t i p l e t r a n s m i t t e r loop coverage can a l s o provide i n f o r m a t i o n on the shape of a conductive body.

In p r a c t i c e the responses observed i n f i e l d s i t u a t i o n s are much more complex than those of simple models, but the r e s u l t s are s u f f i c i e n t l y i n t e r p r e t a b l e that the method has general acceptance and a number of d i s c o v e r y case h i s t o r i e s e x i s t .

SURVEY PROCEDURE:

Holes MTS-53, MTS-54 and MTS-55 and MTS 57 were surveyed on 8-10 June 1988 using the Crone 2.5 kW P.E.M. 8-channel t r a n s i e n t EM system. Two 300m x 300m t r a n s m i t t e r loops were l a i d out around the holes as shown i n Figure 1. These loop p o s i t i o n s give maximum EM co u p l i n g f o r the geologic s t r u c t u r e i n the v i c i n i t y of the d r i l l h o l e s . Primary and secondary f i e l d readings were taken every 10m down the holes w i t h the instrument set at a constant maximum gain of 100%. The use of the higher powered t r a n s m i t t e r and 300m x 300m t r a n s m i t t e r loops increases the a b i l i t y to detect weakly conductive zones and decreases the noise l e v e l on the l a t e r channels.

The boreholes were i n i t i a l l y dummy probed to insure an open passage f o r the PEM r e c e i v e r probe. During these t e s t s i t was discovered t h a t MTS-56 was blocked near the top of the hole and hence was not surveyed using the PEM r e c e i v e r . In a d d i t i o n , MTS-55 was found to be blocked at 240m depth, however, since t h i s was below the depth of i n t e r e s t , t h i s hole was surveyed.

W H I T E G E O P H Y S I C A L I N C .

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M T . S I C K E R - V A N C O U V E R I S L A N D

LOOP LOCATION SKETCH DDH - M T S 5 3 , 5 4 , 5 5 , 5 7

o 100 I 2 0 0 — i — 3 0 0 m = 1

DISCUSSION OF RESULTS:

The borehole PEM p r o f i l e s shown i n Figures 2-5 i n d i c a t e the presence of a weakly conductive h o r i z o n at approximately 180m depth. This conductor has produced a broad, low-amplitude p o s i t i v e , channel 1-2 anomaly o v e r p r i n t i n g the general background p o s i t i v e response. The shape of the response, and the decay c h a r a c t e r i s t i c s i n d i c a t e t h a t a l l boreholes have i n t e r s e c t e d a uniform conductive sheet w i t h a c o n d u c t i v i t y - t h i c k n e s s product of about 0.5 to 1.0 mho/m.

The centre of the anomaly, and hence the depth of i n t e r s e c t i o n of the conductive sheet i s 175m i n MTS-53, 175m i n MTS-54, 195m i n MTS-55, and 175m i n MTS-57. However, because of the broad character of the response, t h i s depth estimate i s only accurate to w i t h i n ±20m. The c o n d u c t i v i t y - t h i c k n e s s product of the conductive sheet appears to increase to the east beneath MTS-55 and MTS-57.

There i s no i n d i c a t i o n of any other conductive zones i n the v i c i n i t y of the boreholes, nor does there appear to be any higher c o n d u c t i v i t y s e c t i o n s w i t h i n the conductive sheet.

CONCLUSIONS AND RECOMMENDATIONS:

Previous borehole PEM surveys of MTS-34, MTS-45, MTS-46, MTS-47 and MTS-48 by Woods (1987, 1988) on the Mount S i c k e r property f a i l e d to detect any conductive m i n e r a l i z a t i o n i n the v i c i n i t y of the diamond d r i l l h o l e s , i n s p i t e of minor sulphide concentrations i n the core. An a r g i l l a c e o u s sedimentary u n i t was encountered i n MTS-53, MTS-54, MTS-55 and MTS-56, which i s most l i k e l y the source of the broad p o s i t i v e response i n these holes.

v. W H I T E G E O P H Y S I C A L I N C .

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I N S T R U M E N T : CRONE! PEM

T I M E B A S E : 10 MSEC

C O N S T A N T GRIN 1 0 0 *

WHITE GEOPHYSICHL INC

MINNOVfl INC. MT. SICKER PROJECT

BOREHOLE PULSE EM SURVEY DDH MTS-53 LOOP B

DRTE: JUNE/88 FIG . 2

I N S T R U M E N T : CRONE PEM

T I M E B A S E : 10 M S E C

MTS-54 1

CONSTANT G A I N 100% B

WHITE GEOPHYSICRL INC

MINNOVFI INC. MT. SICKER PROJECT

BOREHOLE PULSE EM SURVEY DDH MTS-54 LOOP B

DRTE: JUNE/88 FIG. 3

5

The borehole P.E.M. system has an e f f e c t i v e search radius of about 50m to 100m, depending on the s i z e of the conductive t a r g e t , hence i t can be concluded that no conductive sulphide zones e x i s t i n the v i c i n i t y of holes MTS-45, MTS-46, MTS-47 and MTS-48.

Massive sulphide occurrences are known to be q u i t e l o c a l i z e d i n the S i c k e r Group v o l c a n i c s (e.g. Abermin Coronation zone), hence i t i s recommended that other Minnova Inc. d r i l l h o l e s on the Mt. Sicker property be surveyed u s i n g borehole Pulse E.M. to search f o r s m a l l , massive sulphide lenses not i n t e r s e c t e d by d r i l l i n g .

Non-conductive zones of economic sulphides may be detected using downhole IP techniques. Although the search radius i s not as la r g e as downhole EM, an IP survey w i l l i n d i c a t e the presence of sulphide concentrations surrounding a borehole.

Dennis V. Woods, Ph.D., Consulting G e ophysicist

P.Eng.

v. W H I T E G E O P H Y S I C A L I N C .

6

REFERENCES:

Woods, D.V., 1975; A model study of the Crone Borehole pulse electromagnetic (PEM) system; unpublished M.Sc. t h e s i s , Queen's U n i v e r s i t y , Kingston, Ontario.

Woods, D.V. and Crone, J.D. 1980; Scale model study of a borehole pulse electromagnetic system; C.I.M. B u l l e t i n , vol.73, no. 817, pp.96-104.

Woods, D.V., Rai n s f o r d , D.R.B. and F i t z p a t r i c k M.N. 1980; Analogue modelling and q u a n t i t a t i v e i n t e r p r e t a t i o n of borehole PEM measurements (a b s t r a c t o n l y ) ; EOS Transactions of the American Geophysical Union, v o l . 61, no. 17, pp. 414-415.

Woods, D.V., 1987; Geophysical Report on a Borehole Pulse EM Survey Mt. S i c k e r Property Hole MTS-34 f o r Minnova Inc., White Geophysical Inc.

Woods, D.V., 1989; Geophysical Report on a Borehole Pulse EM Survey Mt. S i c k e r Property Holes MTS-45, MTS-46, MTS-47 and MTS-48 f o r Minnova Inc., White Geophysical Inc.

W H I T E G E O P H Y S I C A L I N C .

SPECIFICATIONS - CRONE BOREHOLE PULSE EM EQUIPMENT

PROBE: — Measures dB/dt of axial-component of borehole — Ferrite cored antenna with preamplifier and self contained power supply (Ni.-Cd. rechargeable) — 30 hours continuous operation -Weight : 3.6 Kg. - L e n g t h : 1.63 M. — Diameter: 2.9cm (for U E " holes and larger) -Pressure tested to 13.8 MPa (2000 PSI)

WINCH ASSEMBLY: — 3 speed gear box, gear ratios 1:1, 2:1, 3:1 — Optional power winching for deep holes — Borehole cable capacity of up to 2000 meters -Portable

UNDERGROUND PUSHROD SYSTEM: — For use in horizontal boreholes (< 45 degrees) — Powered Pushrod assembly for holes > 500 meters

BATTERY SUPPLY: ±12 V D C , two internal, rechargeable, 12V gel type batteries

MEASURED QUANTITIES: Primary shut-off voltage pulse (PP). Time derivative of the transient magnetic field by integrative sampling over eight, contiguous time gates (microseconds).

1. NO. WINDOW WIDTH MID PT. R E L GAIN WINDOW WIDTH MIDPT. PP -100 to 0 100 -50 1.00 -200 to 0 200 -100 1 100 to 200 100 150 1.00 200 to 400 200 300 2 200 to 400 200 300 1.39 400 to 800 400 600 3 400 to 700 300 550 1.93 800 to 1400 600 1100 4 700 to 1100 400 900 2.68 1400 to 2200 800 1800 5 1100 to 1800 700 1450 3.73 2200 to 3600 1400 2900 6 1800 to 3000 1200 2400 5.18 3600 to 6000 2400 4800 7 3000 to 5000 2000 4000 7.20 6000 to 10K 4000 8000 8 5000 to 7800 2800 6400 10.00 10K to 15.6K 5600 12.8K

10.8ms. Time Base 21.6ms. Time Base

READOUT: Readings are output on an analog meter (6V FSD), over three sensitivity ranges (XI, X10, X100). Data retrieval made by channel select switch.

TIMING: A telemetry link ("sync") is maintained by radio signal, or a back-up cable, between the transmitter and the receiver, and is meter monitored.

SENSITIVITY: Adjustable through a ten turn, calibrated gain pot.

SAMPLING MODES: U S & H " (Sample & Hold)

The receiver averages 512 (10.8 ms), or 256 (21.6ms), readings for all channels, and stores the results for display. X O N T ' (Continuous)

A running average for all channels is stored, enabling the operator to reject thunderstorm spikes and power line noise by visual inspection.

W H I T E G E O P H Y S I C A L I N C .

SPECIFICATIONS - PULSE EM TRANSMITTER EQUIPMENT

M O T O R G E N E R A T O R :

4 -1/2 H.P. Wisconsin, 4 cycle engine with belt drive to D C . alternator; maximum output 120V, 30

amps; external gas tank; frame unit weight: 33 kg, shipping: 47 kg.

R E G U L A T O R :

Controls and filters the alternator output; continuously variable between 24V and 120V D . C . ; 20 amp

maximum current; weight: 10 kg, shipping: 24 kg.

P E M W A V E F O R M T R A N S M I T T E R :

Controls bipolar, on-off waveform and linear current shut-off ramp time. Radio and cable time syn-

chronization with housing for optional crystal clock sync system; on-off times for 60 Hz areas 8.33ms

16.66ms, 33.33ms; for 50 Hz areas 10.0ms, 20.0ms, 40ms; for analog PEM operation 10.9ms, 21.3ms-

linear controlled current shut-off ramp times of 0.5, 1.0 and 1.5ms; monitors for shut-off ramp operation,

instrument temperature, Tx loop continuity, and overload output current; automatic shut-down for open

Tx loop. Weight: 12.5 kg, shipping: 22 kg.

R E M O T E R A D I O . A N T E N N A A N D M A S T :

Used for radio timing synchronization on large survey grids; range up to 2 km; radio has 12V

rechargeable gell cell battery supply; antenna is fiberglass mounted on a 4 section aluminum mast each

2m long. Radio weight: 2.7 kg, shipping: 6.0 kg; mast and antenna shipped as bundle: 6.4 kg.

O P T I O N A L C R Y S T A L C L O C K T I M I N G L INK :

Installed in the Digital Rx and external box mounted to be plugged into P E M - T x . Gel rechargeable power

supply. Weight: 10 kg, shipping: 15 kg.

W I R E , S P O O L S A N D W I N D E R S :

Transmitter wire is usually No. 10 or No. 12 A W G copper in 310m or 410m lengths, 1 length per spool; 2

spools in a shipping box; winder is mounted on a magnesium packframe.

M U L T I - T U R N M O V I N G C O I L :

7 turn, 13.7 meter diameter Tx loop with plugs to break into 2 sections. Aluminum or ccpner wire and

various coverings depending on area being used.

B A T T E R Y POWER S U P P L Y :

24V, 20 amp hour, rechargeable battery supply for use with PEM-Tx as power source rather than motor-

generator-regulator. In aluminum case, with clamp connectors. Weight: 20.5 kg, shipping: 29 kg.

• Battery chargers supplied for all rechargeable battery units

• All instruments and equipment operational from - 4 0 ° C to + 5 0 ° C .

• Shipping boxes are reusable plywood construction with closed cell foam shock protection.

W H I T E G E O P H Y S I C A L I N C .

9

STATEMENT OF QUALIFICATIONS

NAME: PROFESSION: EDUCATION:

PROFESSIONAL ASSOCIATIONS:

EXPERIENCE:

WOODS, Dennis V. Geophysicist

B.Sc. Applied Geology Queen's U n i v e r s i t y M.Sc. Applied Geophysics Queen's U n i v e r s i t y Ph.D. Geophysics A u s t r a l i a n N a t i o n a l U n i v e r s i t y R e g i s t e r e d P r o f e s s i o n a l Engineer Province of B r i t i s h Columbia S o c i e t y of E x p l o r a t i o n Geophysicists Canadian Society of E x p l o r a t i o n Geophysicists A u s t r a l i a n Society of E x p l o r a t i o n G e o p h y s i c i s t s P r e s i d e n t , B.C. Geophysical S o c i e t y 1971-79 - F i e l d G e o l o g i s t w i t h St. Joe M i n e r a l

Corp. and Selco Mining Corp. (summers). - Teaching a s s i s t a n t at Queen's

U n i v e r s i t y and the A u s t r a l i a n N a t i o n a l U n i v e r s i t y .

1979-86 - Professor of A p p l i e d Geophysics at Queen's U n i v e r s i t y .

- Geophysical c o n s u l t a n t w i t h Paterson Grant & Watson L t d . , M.P.H. Co n s u l t i n g L t d . , James N e i l s o n and Assoc. L t d . , Foundex Geophysics L t d .

- V i s i t i n g research s c i e n t i s t at Geo l o g i c a l Survey of Canada and the U n i v e r s i t y of Washington.

1986-88 - Pr o j e c t G e o p h y s i c i s t w i t h Inverse Theory and A p p l i c a t i o n s Inc.

- Chief G e o p h y s i c i s t w i t h White Geophysical Inc.

W H I T E G E O P H Y S I C A L I N C .