Pipe cleaner

A team from Heriot-Watt University has discovered a novel way to transport natural gas products and prevent expensive blockages that hold up production, potentially saving the industry billions of pounds.

The technique uses chemical additives to prevent gas hydrates forming an icy slush in the high-pressure, low temperature environment of oil and gas pipelines running along the sea bed or through cold regions.

By reducing transport costs and the overall price of fuel production, the technique could allow oil and gas firms to continue exploiting fields that are not fully depleted, but have been abandoned as uneconomical, such as those off the UK coast. This would reduce the UK’s dependence on oil and gas imports.

Hydrates have long been a problem for the industry. Oil and gas companies have previously tried to prevent them from forming by insulating or heating pipes, but this has proved expensive and has had only limited success.

Instead of trying to prevent the hydrates forming, the Heriot-Watt team, led by Prof Bahman Tohidi, director of the university’s Gas Hydrate Research Centre, have introduced chemical additives to the hydrocarbons during transport.

‘The principle is to allow the hydrates to form, but to make them transportable,’ said Tohidi. The additives encourage the methane to crystallise into specially tailored hydrates where the size of the crystals is controlled so that they do not stick together.

Tohidi was unable to disclose which chemicals are used as the technology has yet to be patented.

Instead of forming a blockage, a smooth flowing hydrate slurry is created. This cold flow approach will reduce the operating and capital cost of pipelines as well as their operating pressure. There will also be no need to insulate them.

Transporting gas as hydrates is also safer. If a pipeline is attacked, hydrates burn slowly but do not explode. If pipes rupture, large amounts of gas do not escape.

When hydrates form, methane molecules are trapped individually within a cage-like lattice and can exist much closer together than when in their gaseous form. This means that creating a slurry for transportation will also increase the capacity of pipelines.

Along with another technology, the additive has been awarded research funds from development agency Scottish Enterprise’s 2005 Proof of Concept programme.