Improving data capture

The more you understand about your project in the early stages, the better you are able to plan for and manage risk of it. Aeroquest International's Jonathan Rudd explains how airborne geophysical methods are helping improve information capture.

All projects, from those of a regional nature to those with a small footprint, benefit from an understanding of the geology in the near surface. Airborne geophysical surveys offer mature, non-invasive technologies that provide systematic, quantitative, rapid, cost-effective, information about the near-surface in the project area. Modern airborne geophysical methods offer accurate, high precision, calibrated data sets, which measure the electrical conductivity, magnetisation, natural radioactivity, topography and density. The correct combination of these methods for a given project will provide valuable layers of information for integration and interpretation of the surface and sub-surface characteristics.

With a presence on every continent (barring Antarctica), and as a public company focused exclusively on airborne surveying, Aeroquest International Group of Companies is uniquely positioned to deliver customised turnkey airborne services wherever a project is located. Aeroquest is focused on raising the bar in the Airborne Geophysics Industry, building on its past successes and leadership in our industry. The UTS arm of the company was the first to offer compensated, stinger-mounted magnetics on a helicopter for high resolution, high accuracy magnetic mapping in any terrain. UTS continued to innovate, and developed Ultra High Resolution Airborne Magnetic and Radiometric (UHRAM) surveys. These surveys offer the highest resolution data sets available from a fixed wing platform and are delivered using purpose-built crop-duster aircraft capable of flying safely as low as 15-20 metres above the ground.

Aeroquest was also the first to commercially offer helicopter-borne time-domain electromagnetic (HTEM) surveys. These systems have powerful transmitters that allow for mapping to depths of several hundred metres with great spatial resolution and detail. The AeroTEM system is well-suited to the delineation and interpretation of both discrete targets and stratigraphy in many environments. Helicopter-based systems provide project managers with many technical and logistical advantages, and the AeroTEM system can be quickly employed and has been credited with a number of mineral discoveries.

In this example, the AeroTEM survey is interpreted to produce a 3D model of the variation in the electrical conductivity of the ground. These results are used to map the continuity, thickness and depth of the various layers across the survey area. A conductive shale formation in this area is very important in delineating the underlying sandstone (the reservoir rock), and is also an important element in defining the mining/extraction process for oil sands. The AeroTEM results also effectively map the distribution of aggregate resources at surface. Paleochannels are mapped as relatively resistive units with a very clear morphology and are important as sources of aggregate and water, and for planning the oil sand extraction process.

The application of this technology is virtually limitless. In western Africa, AeroTEM was effective in locating and characterising conductive ground sinks for electrical transmission lines. In eastern Africa, AeroTEM was combined with the magnetic and radiometric methods for mapping potential gas seeps across a prospective licence area. Combining the appropriate EM technology with magnetics and radiometrics allows for the layering of information for a more effective and robust interpretation of the survey results. AeroTEM is currently being used in Yemen for the characterisation of the low velocity layer to improve the static correction of noisy seismic data.

Aeroquest's history is proof of capable guidance, growing an innovative, full-service airborne geophysical company that provides service globally to multiple markets. The company as a whole has acquired and delivered more than nine million line kilometres of high-resolution airborne geophysical data. And Aeroquest's present is focused on further expanding and developing our technologies and services. From a high-resolution magnetic gradiometer to the helicopter-borne AeroTEM system to our frequency domain EM systems, the strength of Aeroquest's product offering is in its diversity and the ability to customise the survey systems and parameters to match the project requirements.

Jonathan Rudd is Chief Geologist at Aeroquest Surveys.