The problem at those depths has been the formation of gas hydrates, ice crystals described as “jelly like” by one former drilling engineer, which filled the top of the container and made it impossible to use it to pump the oil up to the surface.
The problems have highlighted the issue of gas hydrates: strange substances that create a variety of hazards, but may also offer a huge opportunity.
Gas hydrates are formed when molecules of methane or other gases are trapped in water crystals. They are found at the sea bed and trapped in permafrost, created by high pressure and low temperature environments.
They are well-known hazards for pipelines, but many aspects of their behaviour are still not fully understood.
It has been suggested that they may have been responsible for the leakage of gas into the Deepwater Horizon’s drill riser that appears to have caused the last month’s explosion.
A presentation last year by an engineer at Halliburton, the oil services company that was responsible for cementing the well to secure it, highlighted the risks that could be presented by gas hydrates for deep-water cement jobs.
The presentation warned:
Gas flow may occur after a cement job in deepwater environments that contain major hydrate zones.
Destabilization of hydrates after the cement job is confirmed by downhole cameras.
The gas flow could slow down in hours to days if the de- stabilization is not severe.
However, the consequences could be more severe in worse cases
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