GAS BUBBLES that lead to explosions when drilling for oil can now be detected with laser light, using a technique developed by researchers at Reading University.
As a drill approaches an underground gas pocket, the increasingly porous rock gives off natural gas bubbles from the underlying gas and oil reserves. This gas, within the slurry around the drill, can ignite due to the red-hot friction of drilling.
Using sheets of laser light, the slurry around the drill tip is illuminated. Passing through the laser light, the bubbles bend the light and the amount of bending is measured to differentiate between gas particles and rock particles.
Bubble size and speed can also be determined by measuring the time intervals between bubbles lighting up adjacent sheets of laser light.
Detection of the bubbles will enable drill operators to respond in time to stop any potential explosion. To prevent the gas bubbles from developing, pressure can be increased at the point of drilling.
The operator will do this by modifying the lubricant mix normally used to keep the temperature as low as possible. The lubricant is water based and has rock material added to it to increase its mass and so increase the pressure it brings to bear when it reaches the bottom of the borehole.
Blowouts caused by gas bubbles can render boreholes useless for oil and gas extraction. Filling the borehole with rock, concrete and other materials, and then redrilling, is the only way to halt the uncontrolled release of natural gas and oil, and to ensure the proper extraction of these resources.
The huge costs associated with this remedial action mean that this new development could save the oil exploration industry millions of pounds. The technique is expected to come into commercial use within the next two years.
Copyright: Centaur Communications Ltd. and licensors