Drone based Geophysics
Improvements in the design and functionality of flight control systems have transformed drones to industrial-grade tools capable of acquiring high-quality geophysical measurements. Significant advances have also taken place in the development of miniaturized sensors specifically designed or adapted for UAV payloads, including geomagnetic and geo-electromagnetic sensors. Drones have established a presence in the corporate world over the past ten years. MGT has developed industry-specific solutions, esp. for the mining industry and for near surface applications.
Drones in Geophysical Exploration
- Increasing work efficiency and productivity, reducing labor and production costs
- Improved measurement accuracy, drape flight, wide area surveying
- Surveying of remote areas that are inaccessible by foot or costly for the deployment of manned platforms
Unexploded ordnances (UXO) pose a significant public safety hazard in many parts of the world. They occur on or near the surface and down to depths of several meters below the ground. One of the most established techniques for ordnance detection is magnetics. This method is very effective at locating buried metallic objects. MGT has developed a multisensory system that allows for cost effective wide area scanning with near 100 % coverage and near 100 % detection.
In recent years an important development in aeromagnetic surveys is the application of unmanned aircrafts. Compared with ground surveys UAVs allow faster and cheaper coverage of large areas. Such systems can be used at low altitude and in hostile environments that would not allow helicopter surveys. The use of UAV is ideal for collecting very dense data over small grids. Autonomous flight capabilities are very efficient and enable using drape flying in which the data is collected at constant terrain clearance.
Numerical Modelling and Inversion
Inversion is the mathematical process of calculating cause from a set of observations. In resistivity work, it is used to calculate the resistivity of different formations in the ground from a set of readings taken at the surface or on aerial platforms.
In geophysics, an electrical resistivity survey is conducted to map the subsurface of the earth. The measurements are performed using a powerful electric source on ground which injects a current. The drone, either rotory or fixed wing drones, carry magnetometers which pick and record the responding magnetic field. It results in a large data set which is processed and transformed into transfer functions.
The area of penetration is not exactly known since it depends on the underground conductivity distribution. It is the job of the inversion process to calculate a conductivity distribution under the survey area as accurately as possible.
Pipeline Detection and Localization
Pipelines are a mode of transportation for oil, gases and other fluid products, e.g. hydrogene. As a means of long-distance transport, pipelines have to fulfill high demands of safety, reliability and efficiency. Subsurface pipeline detection and localization is an important problem in gas and oil transport as well as in construction and excavation missions. MGT uses an unique UAV airborne electromagnetic methodology that allows locating buried pipes, cables and sewers with unprecidented accuracy.
The current and continuing drought in parts of Europe and other parts of the world, the demand from water users, including municipal, industrial, agricultural and environmental needs, has impacted groundwater resources.. Groundwater exploration programs are focusing on deeper (500 to 1000 metre below ground surface) production zones. But the costs of deep groundwater production wells can approach $1million. UAV airborne geophysical electromagnetics can reduce risk and unnecessary costs by assisting in the siting of wells in locations with the most potential to produce acceptable quantities of water. MGT uses a hybrid airborne electromagnetic method with a fixed electric source on the ground and a roving receiver attached to a drone.