We use a Simple Multi-Borehole Resistivity Method for Small to Large Scale 3D Imaging.

Its a good idea to carry out in-person domestic and international mine site visits to get a better appreciation of their scale and scope. It also reminds us that mine deposits eventually get depleted so its important to make new economically feasible discoveries to feed the mills and keep everyone employed.

ClearView Geophysics Inc. of Brampton, Ontario has expanded depth-to-bedrock investigations to include waterway and river crossings, primarily for HDD (horizontal directional drilling) applications. 

Many mineral exploration projects are completed from base camps located in remote areas.  This requires gear to be crated and shipped by plains, trains and automobiles…and trucks.

Borehole Time-Domain EM (Electromagnetics) Surveys are carried out using a large fixed loop with electricity powered by transmitters on surface.  ClearView uses Geonics TEM57 transmitters and TEM67 power modules.  Currents up to 28 amps can be applied to 10 gauge copper wire loops. The PROTEM receiver records the results typically with a base frequency of 30 Hz but occasionally with 3 Hz for stronger conductors.

CSAMT (Controlled Source Audio-frequency Magnetotellurics) are an effective way to image the ground resistivity by collecting ‘soundings’ at each location. Readings taken in the ‘Scalar-Mode’ use one magnetic sensor which is oriented perpendicular to several 25-metre or 50-metre electrical dipoles.

Distributed Array surveys (DAS) are recommended for deep complex anisotropic targets where near surface resolution is a lower priority.  Hardware advances over the past decade make it possible to to acquire large quantities of data in a relatively short amount of time. 

A Geometrics Geode with ability to record up to 65,536 samples per record allows high resolution data to map stratigraphy and structure to depths up to 2 km using a trailer-mounted 800 lb weight-drop system.  A ‘seismic gun’ is sufficient for shallower investigation depths. 

The Geonics EM34-3XL ground conductivity meter can be applied in ‘rover-mode’ for high resolution coverage in a short amount of time.  The onboard ‘Archer²‘ datalogger collects real-time GPS at 1-second intervals tagged to Apparent Conductivity readings at 5x per second.

Abandoned wells need to be located and decommissioned. There are several steps required in order to accomplish this. The first step is to search for drill logs filed with the City/Region or MOE. 

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

Gravity Surveys are used for many applications, including gold, base metal and diamond exploration.  For geotechnical applications it can be used to detect buried bedrock escarpments, for example.  

Cross-hole IP/Resistivity Surveys are carried out with C1-C2 transmitter current electrodes at ‘infinity’ perpendicular to the target strike and on each side of the target. 

ClearView owns and operates a Sensors & Software Conquest 100 System for concrete scanning services.  This compact 1 GHz GPR instrument includes an added-on power cable detector.

ClearView Geophysics Inc. carries out large loop TDEM surveys for base metal, uranium and graphite exploration using Geonics PROTEM receivers and TEM57 transmitters with TEM67 power modules. 

Geotechnical engineers require accurate parameters for designing buildings, foundations, rock slopes and so forth. The shear-wave velocity of the ground is a useful part for determining common geotechnical parameters such as Poisson’s Ratio and Shear Modulus.

There are many types of ‘targets’ that geophysics can be used to detect.  For exploration, targets can be gold, base metals, specialty metals, diamonds and sand/gravel deposits, to name a few.

The Dipole-Dipole electrode configuration is ideal for detecting off-hole targets because the transmitter and receiver electrodes are always at the same distance apart as the configuration moves down the borehole.

The main thing with our cross-hole IP system is that it’s simple, with single wires down each hole, and there are many readings taken at different angles making the inversion converge very quickly even with tight constraints (e.g., UBC low chi factor).