Lasers Could Improve Drilling Safety
READING, UK -- If you shake a bottle of cola and open it, you get a sugary mess. If you open a pocket of high-pressure gas in the borehole of an oil well, you get a catastrophic blowout. A laser-based technique proposed by scientists at the University of Reading, however, could prevent such accidents, saving the petroleum industry millions of dollars each year in damages and lost production.
The sudden release of pressurized gas in a borehole spells potential injury to drillers, damage to equipment and a major risk of fire. Increasing pressure on the slurry at the drill bit can prevent blowouts, but drillers must be aware of their proximity to a high-pressure pocket. The technique would use a laser to examine the bubbles that form in slurry as the drill bit approaches a gas pocket.
Illuminating the slurry with a laser would make the bubbles visible. Timing the interval as the bubbles pass between two lasers would measure their size and velocity. The angle at which the light diffracted could offer information about the optical qualities of the gas bubbles and differentiate them from small particles.
Researchers at the University of Reading have proposed a laser-based technique that could prevent blowouts in oil wells.
David Waterman, a physicist on the project, said that a detector for the surface monitoring of slurry could be developed within a year or two.
HeNe lasers operating at a few milliwatts would be adequate as the light source and would require no special handling or miniaturization.
The researchers' goal is to develop a system that could operate close to the tip of the drill bit. Fiber optic cables, carrying light deep into the hole and bubble information back to the surface, would offer a true early warning system, allowing rapid response to a change in the character of the slurry.
Developing such a system, however, will require more work. "Boreholes are very aggressive places," said Waterman. He explained that fiber optic cables are easily damaged in the high-temperature and -pressure environment, which is strongly saline. They also tend to absorb water, changing their optical properties.
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