Airborne Geophysical Services > Survey Technology

Introduction

DIGHEM Fugro Gravity & Magnetic Services with Fugro Airborne Surveys provides a complete suite of airborne electromagnetic (AEM) systems, both helicopter-mounted (HEM) and installed on fixed-wing aircraft (FWEM).

Fugro Airborne Surveys and its predecessor companies have over forty years of experience in developing successful AEM systems and providing surveys. This research on and development of proven AEM technology, as well as maintaining worldwide survey capability, continues today. Our goal is to anticipate, and provide, effective AEM solutions for the exploration/mapping challenges of our clients. If you have an exploration/mapping project, discuss it with us. Our experts will work with you to provide an AEM system, focused to provide an effective solution.

Helicopter Electromagnetics

Our HEM systems, RESOLVE and DIGHEM, are ideally suited for surveys where moderate depth penetration is required - especially if located in an area of rugged terrain. The HEM frequency domain transmitter and receiver coils are located in a cylindrical rigid bird slung beneath a helicopter. Spatial resolution of the targets is maximized due to the smaller search footprint made possible by the lower sensor altitude. This, and the ability to maintain consistent terrain clearance in mountainous areas, are inherent to helicopter surveys. The compact, symmetrical transmitter-receiver geometry produces data independent of flight direction which is beneficial for interpretation of target geometry. HEM is extremely efficient for small or irregularly shaped survey areas. The HEM system is generally installed in a local helicopter which reduces mobilization costs and/or delays.

More recently, Fugro Airborne Surveys has developed the HeliGEOTEM system, which incorporates the proven characteristics of the GEOTEM system. HeliGEOTEM combines the greater horizontal resolution and flexibility of helicopter mounted time-domain EM systems and the proven GEOTEM/MEGATEM technology.

In addition to our core mineral exploration solutions, Fugro Airborne Surveys has developed specialized HEM systems and completed successful surveys for groundwater, engineering, hydrocarbon alteration mapping and environmental studies.

Fixed-wing Electromagnetics

Fugro Airborne Surveys offers three FTEM systems: GEOTEM, MEGATEM, and TEMPEST, each with a special focus. With these systems, the time-domain transmitter loop is mounted upon a dedicated fixed-wing aircraft, e.g., Casa, Dash 7, or Skyvan, with the receiver coil towed behind in a small bird.

The large scale and high transmitter power of these systems provides a large effective depth of exploration/mapping as well as a large search footprint. This large scale, however, can limit the spatial resolution for target interpretation.

GEOTEM and MEGATEM are typically used in mineral exploration where bedrock internalization is the target, often covered by thick, conductive overburden and/or embedded in a conductive host but are also used for mapping hydrocarbon alteration effective petroleum exploration. The original GEOTEM developments, commencing in 1985, were enhancements of the successful INPUT system. Mounted on a CASA 212 aircraft, GEOTEM has been continuously upgraded to provide a system with proven success worldwide.