Spectral IP and Resistivity

Spectral Induced Polarization & Resistivity surveys (IP & Res) are excellent methods for detecting disseminated sulphide mineralization that could be associated with gold. The surveys are carried out using surface and borehole modes.

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Large Loop TDEM

ClearView Geophysics Inc. owns and operates transient PROTEM receivers and TEM57/67 transmitters built by Geonics. This system has proven itself useful for detecting both good and bad conductor sulphide mineralization located both shallow and 100’s of metres deep.  It is also useful for detecting sources of water.

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Snowmobile-Mode Cesium Magnetics

Cesium magnetometer surveys are carried out using a custom-built sleigh pulled behind a standard snowmobile.  This system has proven itself on numerous large-scale mineral exploration projects during the past 15+ years. 

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Seismic Refraction

Seismic Refraction surveys are typically carried out for depth to bedrock investigations.  The "shot" can be either an explosive or hammer source.  Interpex IXRefraX software is used to process the data.

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Electromagnetic (EM) and Magnetic surveys

EM and Magnetic surveys are perhaps the most common geophysical methods used on mineral exploration and environmental investigations. The most commonly used EM instruments for environmental investigations are the Geonics EM31 and EM61.

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GPR ( Ground Penetrating Radar )

GPR works best in low conductivity areas. Conductive materials (e.g., clay) attenuate the GPR signal to the point that very little depth penetration is achieved. Penetration is greatest in unsaturated sands and fine gravels.

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Gravity

Gravity surveys are completed for a number or applications, including mineral exploration (e.g., diamonds) and geotechnical investigations (e.g., escarpments).

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Geophysical Interpretation

ClearView has extensive experience interpreting airborne and ground-based geophysical data. We use UBC's suite of inversion software to produce 2D and 3D interpretations of total field magnetics and IP/Resistivity data. Post-processing software is also used to produce various derivative datasets and maps.  

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Welcome to ClearView Geophysics

ClearView Geophysics Inc. is a geophysical services company founded in 1996.  There is no better way to collect high resolution sub-surface data than with ground-based sensors or 'boots on the ground'. When you describe your project goals to us, we will design a geophysical survey to help you achieve those goals in the most cost-effective manner possible. Getting ground-based geophysical data is arduous - so we are constantly working to find ways to make it easier, whether its with our snowmobile- and ATV-mode surveys or with exo-skeleton systems for more supportive and safer fieldwork.

Joe Mihelcic, P.Eng., M.B.A.
Geophysicist, President & Owner

About the Owner: Mr. Mihelcic is an Applied Science '88 Geological Engineering (Geophysics Option) graduate of Queen's University at Kingston and '95 MBA graduate of Ivey Business School at the University of Western Ontario in London. He enjoys designing and implementing off-the-shelf components and technologies to make ground geophysical surveys easier and therefore more cost effective. He also writes his own software to streamline processing and interpretation.

Borehole FWS (Full Waveform Sonic) Surveys

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FWS (Full Waveform Sonic) borehole surveys can be an alternative to Borehole shear-wave seismic surveys in certain cases.

Borehole Shear Wave surveys use 1 or 2 borehole geophones that are 'clamped' against the PVC cased borehole wall.  Ideally the holes are dry.  Seismic shear waves are generated near the borehole collar using a hammer against a plank held in place under the wheels of a truck.

FWS can be used to determine Poisson's Ratio by measuring Vp compressional and Vs shear Wave velocities down the borehole in a single self-contained borehole probe. The method requires the borehole to be filled with water.  The main disadvantage of FWS compared to borehole seismic surveys is that the borehole needs to be uncased and as small diameter as possible.  This might be difficult through soft soils so the borehole should be logged immediately after the casing is pulled by the drill crew.  In some cases the drillers may need to fill the borehole with water to allow the survey to commence.

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The ALT QUL40-FWS tool with a 4MXA-1000 (500m) motorized winch is used for the FWS survey.  A Makita motor-generator with Panasonic Toughbook laptop is used to log the data.  A typical FWS tool configuration has 1 transmitter and 3 receivers, as displayed below.   

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More specifically, the ALT QL40-FWS tool is specifically designed for the water, mining and geo-technical industries. The QL40-FWS implements a high energy source generated by a ceramic-piezoelectric transducer that excites the formations in such a way that waves of different frequencies are developed and propagated. Real time analysis and processing of the full waveform are performed by the tool to enhance the picking of the different wave propagation modes. The tool can only be operated in a fluid-filled hole. Logging speed depends on tool configuration and acquisition parameters.

The FWS Seismic data are typically post-processed as follows using the FWS Module of WellCAD version 5.2 or later.  All data are preserved in raw <*.tfd> and processed <*.WCL> digital formats:

1)A low cut, low pass, high cut, high pass filter to the frequency spectrum is applied.

2)Stack traces 5x.

3)Determine 1st Arrivals using a ‘standard’ method which uses a blanking-factor and threshold factor.  Also use an ‘advanced’ method which computes the ratio of the average amplitude values of the ‘small’ (signal window) and the ‘large’ (noise window).  The transit time at the first sample for which the signal to noise ratio is larger than the specified ‘ratio threshold’ is returned in a Well log.

4)A stand-off correction of 0.0766 m and fluid slowness of 689.655 microseconds per metre (i.e., 1450 m/s) can be applied to correct for the water column around the probe in the borehole.  This is typically only required when analyzing the results with single receiver.

5)Velocity Analysis using ‘Semblance’ is completed for each receiver on the stacked traces (step 2 above).

6)The ‘P-Slowness’ (reciprocal of P-Velocity) is calculated as follows: (Rx2-Rx1)/0.2. However, this assumes the first arrivals are P-waves and not first arrivals through the water column which has a velocity of 1450 m/s.

7)If the S-wave is detected, the ‘Approx S-Slowness’ can be drawn manually on the Velocity Analysis output of step 5.

8)The ‘Adjust Extremum’ process can be completed to produce a more accurate ‘S-Slowness’ result from step 7.

9)Poisson’s Ratio can be computed using the ‘Velocity Analysis – max’ (S-Slowness) and P-Slowness.

 

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