Magnetotellurics with SQUIDs

Methods to map the geological structure of the ground underneath our feet have long been of significant interest both to earth scientists, and to industry, with obvious importance to mining, oil and gas exploration, groundwater extraction, pollution monitoring and other activities.

Geophysical exploration techniques are a way to survey underground, without the expense of digging boreholes. Seismic sounding - measuring reflections of acoustic waves from controlled explosions - offers a powerful, but expensive, way to carry out a one shot survey. Techniques such as ground penetrating radar allow us to probe the ground at far lower cost with an electromagnetic signal, but the depth to which they can reach is limited by this probe signal. Magnetotellurics (MT) is a technique which uses the natural fluctuations in the geomagnetic field as a probe signal. By taking precision measurements of these signals at multiple sites on the surface we can probe to depths of several kilometres. But as these signals are very weak, it requires sensitive magnetic sensors and sophisticated noise rejection.

We have developed such a system, based on SQUIDs (Superconducting Quantum Interference Devices) for the cryoEDM experiment - a particle physics project aiming to measure the neutron electric dipole moment, and thus study the origin of the matter-antimatter asymmetry of the Universe. We believe the innovative hardware and software we have developed could make SQUIDs a suitable alternative to existing sensors used in MT, and thus improve the resolution and depth which can be reached.

This project aims to investigate this idea further. We will carry out a combination of computer modelling and measurements of the magnetic noise at typical field sites, in order to calculate the resolution which could be reached using our system and the potential improvement on existing techniques. In addition we will investigate the many possible applications of this technology to determine the specific needs (resolution, depth, working environment), and the size of the potential market. Thus we aim to identify which areas are the most promising for this instrumentation. We will then develop our design further.

At the present moment we can see many possible applications of SQUIDs in magnetotellurics, but we do not have answers to the questions that potential investors would like to know, such as: what is the potential improvement in resolution to which we can map the electrical conductivity at different depths? How susceptible is the technique to magnetic noise? Can it operate in a noisy industrial environment? This project will allow us to answer these questions. It will help identify the most promising potential market, and thus provide a step to the next stage in the commercialisation of this technology.

At the end of this programme, we will have the technical data to allow ISIS Innovation to protect the relevant IP and promote this idea to potential industrial partners.