Reliable

Characterization of aquifers from the very near surface to over 400 metres

SKYTEM SYSTEMS CAN BE OPTIMIZED FOR TARGETING NEEDS

SkyTEM continues to deliver innovative airborne electromagnetic TEM systems that match scalable system configurations to achieve project-specific goals, from detailed near-surface exploration to deep target imaging, even combined with GRS and B-field.

The latest developments include newly developed High Power (HP) systems mounted on a revolutionary rigid and lightweight carbon frame. The new generation of systems are specifically designed to:

  • Explore deeper and at higher elevations
  • Improved characterization of geology and conductors through the use of integrated B-field and exploration proven 12.5 Hz repetition frequency
  • Reduce exploration costs due to fast flying (up to 150 km/h) and increase production with lightweight frames
  • Review data within 48 hours – allowing clients to customize systems within a few hours

FLEXIBLE SYSTEM CONFIGURATION

The three most common SkyTEM configurations available are summarised in Table 1. Additional system configurations are available to exactly match the exploration objective.

Table 1
SUPER LOW MOMENT (SLM)LOW MOMENT (LM)HIGH MOMENT (HM)SUPER HIGH MOMENT (SHM)
SkyTEM304
SkyTEM306
SkyTEM312

304

This the system has been built its reputation on as THE go-to provider of time domain electromagnetic data acquisition for near surface water and geotechnical exploration projects. The SkyTEM 304 is specialised to resolve the small differences in conductivity.

The success of the system is due to the pioneering dual moment capabilities which has been proven to provide the highest quality near surface data worldwide, and is used by governments and regional water authorities worldwide.

High resolution near surface at a glance

  • Calibration of the system ensures that it is possible for comparison between the borehole conductivity logs and drilling results, with confidence
  • Comprehensive in flight system parameters such as measurement of altitude and inclinometer together with publicly available filter parameters and extremely stable transmitter current waveform mean that rigorous quantitative interpretation is possible
  • Technical Specifications?

    306

    The 306 and 306 HP systems are specifically designed with the customers in mind looking to strike a balance between ultra high resolution near surface and also mapping to depths. This system with our patented dual moment technology is perfect for delivering success when multiple goals are in play.

    The SkyTEM306 HP (High Power) with six transmitter loop turns collects both near surface and deep data. The SkyTEM306 HP can be configured with SkyTEM’s breakthrough dual-moment innovation for faster turn-on and turn-off, recorded by fully digital 3 channel receivers. Furthermore, SkyTEM306 HP can be configured in FAST mode, featuring an aerodynamically superior system reducing acquisition costs by flying at speeds of up to 150 km/h, providing an economically viable alternative to fixed wing, particularly when cost-effectiveness and data quality are crucial parameters. Read further about SkyTEM306 HP here.

    312

    Over and over the mineral exploration companies shared that our system needed to be more powerful, we listened and developed the new high power, deep looking single moment only SkyTEM 312HP.

  • NIA >1,000,000
  • Maps to depths in excess of 600m with unparalleled detection capability
  • High signal to noise improvements, mapping resolution of subtle resistivity contrasts is further magnified
  • The high power, deep looking single moment only SkyTEM312HP, with an NIA of over 1,000,000 replaces the much larger footprint SkyTEM516, is capable of mapping to depths in excess of 600m with unparalleled detection capability. Mapping resolution of subtle resistivity contrasts is further magnified by the very high signal to noise ratio improvements available from SkyTEM312HP. Low noise levels are made possible by SkyTEM’s unique null coupled receiver coils and its rigid, aerodynamically stable frame. The optional 12.5Hz base frequency of the 312 makes it possible to collect off time data as late as 35ms increasing the prospect of detecting deep anomalies, with the MultiMoment 306HP remaining the all-rounder system.

    Technical Specifications?

    Calibrated Data

    Allowing rigorous analysis and accurate geological interpretation

    SkyTEM FAST

    SkyTEM, architects of the only DualMoment TEM technology, once again take airborne geophysics to the next level with the fastest helicopter data acquisition available. Engineered with a rigid aerodynamic carrier frame SkyTEMFAST remains straight and level during high-speed flight benefiting data quality as well as survey efficiency and economy. Data is able to be collected at speeds of up to 150kph with a late time gate of 15ms and 510,000 NIA to maximize depth of penetration. This system is ideal for large regional surveys and data collection over level terrain, with low terrain clearances of between 40 to 60m possible, combined with the ability to drape fly. The helicopter platform also offers logistics flexibility, potentially lessening the need for long refuel ferries.

    SkyTEMFAST enters the marketplace as a value for money alternative to fixed-wing EM, particularly when cost-effectiveness and data quality are crucial considerations when simultaneously collecting the highest resolution multi-use datasets in the near surface and at depth

    Greater Certainty

    Quickly and confidently identify economic and productive drill targets

    Calibrated and Repeatable Data

    The SkyTEM system is the only system calibrated at the Lyngby test range in Denmark, allowing for direct comparison with previous SkyTEM and ground based or borehole EM datasets together with complete traceability back to the Lyngby TDEM reference model.

    The nature of both SkyTEM’s frame and the hardware means that the raw data is well-calibrated (i.e. system bias is below background noise level and there is negligible drift). The receiver coils are placed so as to be null-coupled to the primary field of the transmitter, in order to minimise the self-response of the system. The bias signal from the transmitter is very low, meaning that regular excursions to high altitude to monitor the bias response are not necessary during each flight. In terms of applications and benefits to customers, this means that:

  • Data can be processed and inverted in the field, allowing rapid assessment of survey results and planning of infill lines whilst a survey is in progress.
  • This preliminary EM data, delivered within 48 hours of acquisition, is very similar to final office-processed data;
  • No levelling of the electromagnetic data is required between flights or infill campaigns Surveys done at different times and with different SkyTEM instruments can be seamlessly stitched together (see Figure 1). This gives the option of flying multiple systems concurrently on large surveys for faster completion of acquisition;
  • Results can be used for quantitative analysis of data (e.g. groundwater quality vs. geophysical response) and 4D monitoring (i.e. time-lapse) datasets can be acquired for groundwater monitoring applications.
  • Figure 1 – SkyTEM data was flown three weeks apart and stitched without leveling.

    The boundary between the two survey blocks is indicated by the red arrows on the centre and right-hand panels.

    Mineral exploration survey data example

    In-Loop Geometry

    In-loop geometry means fewer corrections need to be applied to correct for lag offsets, thus preserving the integrity of the originally measured data, together with higher accuracy as to where the anomaly originated. Additionally, the rigid slung load platform’s position and orientation is continuously monitored and together with its separation from the aircraft means that Caesium-vapour magnetic data is not being corrected with lower frequency response fluxgate data in the compensation calculations. Corrections regarding frame geometry are actual and not approximated.

    Confidence in the DATA

    Unlike many other systems, SkyTEM’s low drift means that frequent flights to high altitude to determine drift corrections are not required (some systems require this test several times per flight). On longer surveys, repeat flights to high altitude are conducted approximately weekly in order to verify that the null-coupling, bias and standard deviations have not changed. High altitude checks are also performed following any potential damage to the frame (e.g., hard landing) or replacement of major electronic components.

    • Primary Field Compensation (PFC) allows earlier time channel data to be used in the aLCI inversion, thus resolving shallow layers even more effectively than before.

    A spectral analysis will be performed daily on raw, unstacked data to monitor for VLF and sferic activity. In any case our primary sensor (due to the in-loop design of the system) is the Z and is significantly less affected than other systems.
    Data will be re-flown at the Contractor’s expense when the standard deviation of the normally processed late (e.g. 8904 μs for the 304) time gate EM channel continuously exceeds 2 nV/m2 for Z-component data and 6nV/m for X-component data over a horizontal distance of 2 km under normal (conditions free of man-made interference e.g powerline interference, radio transmitter, etc) survey conditions.

    Fast data collection

    Over large areas often for the price of a few boreholes

    The patented Dual-Moment/MulitiMoment nature of SkyTEM means that it is the only system in the world capable of resolving both shallow (<50m) and deeper (>500m) information in a single survey. This provides customers with a multiple-use dataset, with single-pass surveys providing:

    • Detection of deep bedrock mineralisation and shallow sediment hosted mineralisation;
    • Assessment of deep and surficial aquifers, including connectivity between the two;
    • Information on material above deep ore bodies (e.g. depth of weathering, groundwater reserves, etc.) which are critical to mine planning after the resource has been defined.

    SkyTEM also offers a number of distinct advantages over Frequency EM (FEM) for shallow quantitative mapping, including:

    • A dense dataset well-suited to quantitative interpretation via inversion, unlike the sparse datasets from FEM methods (in-phase and quadrature data at 5 or 6 discrete frequencies);
    • No requirement for levelling, which is an essential and time consuming processing step for FEM. Field processed SkyTEM data is immediately suitable for inversion;
    • Superior depth of penetration in conductive ground;
    • SkyTEM is insensitive to magnetic anomalies, whereas the low frequency in phase FEM response can be highly affected by magnetic anomalies.

    Unsurpassed Range of Investigation Depths

    The patented Dual-Moment/MulitiMoment nature of SkyTEM means that it is the only system in the world capable of resolving both shallow (<50m) and deeper (>500m) information in a single survey. This provides customers with a multiple-use dataset, with single-pass surveys providing:

    • Detection of deep bedrock mineralisation and shallow sediment hosted mineralisation;
    • Assessment of deep and surficial aquifers, including connectivity between the two;
    • Information on material above deep ore bodies (e.g. depth of weathering, groundwater reserves, etc.) which are critical to mine planning after the resource has been defined.

    Figure 2 – Joint inversion of both moments

    deep detection data

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