Geotek were interested in the non contact resistivity project developed for the British Geological Survey. The prototype would not work with their system as the sensor head needed to be 6.5 metres away from the main electronics. There were no more funds to redevelop the system. We decided on another way to achieve this and Derek and I developed a totally new system of which Geotek took the first prototype. It was successful and over the years it has evolved to be an extremely sensitive and reliable piece of equipment, over 130 units have been built to date.

It is used on oil drilling rigs to measure the amount of salts in the rock core samples from the borehole.

Oil was formed deep underground from the remains of carboniferous forests millions of years ago. Temperature and pressure converted the forest remains into oil which generally rises up to the surface through fissures in the rock. However if salts were present when the rocks were formed they solidified out in the fissures . In this case the oil stays trapped underground forming vast deposits under what were called 'salt domes'.

So when drilling for oil if there is no salt in the rock cores the the likely hood of oil being nearby is remote, so they can proceed at full speed (2mm per rev of the drill).

As soon as a high salt content is measured then drilling proceeds with caution to prevent the chance of a 'gusher'