Advanced Geophysical Operations and Services Inc. (AGCOS) took part in Near Surface Geoscience 2018 Conference & Exhibition, 9-12 September 2018, Porto, Portugal and presented the following papers:
In a number of cases, it is necessary to combine several methods during geological mapping and exploration projects. For hydrocarbon exploration these are MT-MVP, TDEM, FDEMS-IP, CSAMT, less often AMT, MT, MVP, DES-IP, TEM. It is difficult at times for a contractor to acquire various equipment sets and maintain software for processing, visualizing, analyzing and interpreting data. To overcome these difficulties, increase efficiency and productivity of the entire integrated electroprospecting complex, designed were 4-channel and 8-channel broadband multifunction EM instruments GEPARD including all the necessary sensors and accessories for field data acquisition, processing, editing and analysis of all ground EM methods. EM data acquisition system is complemented by low power portable multifunction current source for investigations with control source methods up to 200-300m. For deep investigations with a controlled source, other mid-range and high-power transmitters can be used. However, the main focus for the deep soundings is on successful integration of MT, AMT and MVP methods as the most geologically and economically effective for investigations in the 10-150000m depth interval. Positive experience of integrated EM surveys has been accumulated in North America, Asia and Africa using instruments adapted for both ground and marine EM data acquisition system applications.
Recently developed and currently available on the market multichannel broadband multifunction EM instruments of the generation 5+ have levelled the costs of one measuring channel as well as field survey productivity during investigations of shallow geoelectric sections (up to 200m) with geometrical and induction EM soundings methods. Hence, it raises question of comparing resolution capabilities, sensitivity, productivity of geometrical and induction EM soundings methods during investigations of shallow sections. Research carried out by the authors has shown that the control source frequency domain electromagnetic sounding method (CSFDEMS or formerly FDEMS-IP) is the most sensitive to variation of parameters in the geoelectric sections, and subsequently, the most accurate for mapping boundaries of geoelectric section’s layers. The FDEMS method was developed in former USSR in the 50s of previous century together with MT and TEM and was mainly unknown in western countries. Since then, extensive FDEMS method field application experience has been accumulated and with new capabilities of recently developed equipment and software it became sensitive, highly productive and EM noise resistant method.
Australian geoscientists have made a significant breakthrough in mining exploration by establishing that anomalies of high electrical conductivity in the lower part of the Earth’s crust and upper mantle are commonly observed in the regions with large polymetalic and gold deposits. From these deep zones conductive pathways (fingers) rich with thermal fluids extend all the way to the Earth’s surface (ore deposits). To further develop this idea, Australia is currently conducting broadband MT surveys on a regional scale (1: 5 000 000) of its entire continent (AusLamp project) with the objective to discover new mining provinces. The analysis of MT and MVP data obtained in the territory of other countries which have been actively conducting deep investigations fully support findings of Australian geoscientists. Based on the above, as well as accumulated extensive MT/AMT and MVP surveys experience, it will be expedient to further subdivide exploration in wide depth intervals for new large mineral deposits into 4 stages.