Deep see

An autonomous underwater vehicle (AUV) system developed in the UK could help cut the time and money spent by the offshore industry on the inspection of deep water oil and gas pipes.

Developed by Heriot-Watt University spin-out company Seebyte, the Autotracker system carries out detailed, high-speed surveys of submerged equipment.

According to BP, which helped fund the project, it could partially replace traditional inspection techniques within three years.

As oil and gas companies reach ever-deeper areas of the ocean in the hunt for fossil fuels, inspection techniques that are effective on pipelines in shallower waters are increasingly found wanting.

These rely on sonar-based systems towed by ships and are used to build up a map of the ocean bed. According to Seebyte’s Dr Jonathan Evans, not only do such systems provide a low-resolution image of the oil pipeline, but the ‘bobbing’ forces encountered by the towing cable also create inaccuracies in the data.

For more detailed surveys, the offshore industry sometimes uses tethered remotely operated vehicles (ROVs). While these can be used to carry out an up-close video inspection of the pipework, they are extremely slow and need a support vessel and a crew of up to forty.

The problems inherent in existing systems were brought into stark focus in the Gulf of Mexico last year when, in the face of Hurricane Ivan, the area’s offshore operators actually ran out of support vessels.

Evans said that Autotracker is expected to help, as it can survey pipes more quickly and in more detail and does not require the huge back-up operation demanded by traditional techniques.

While an earlier version of the system underwent BP-funded tests last September on Orkney’s Piper/Claymor to Flotta pipeline, Evans said that improvements mean that it is now almost ready for mass-deployment in deep water. Following further tests in Orkney this summer, the group hopes to take Autotracker to a deep-water site in the Gulf of Mexico next year.

The upgraded system features a bigger range of acoustic scanning technology, but Evans said that the biggest technical improvement is the addition of an obstacle avoidance system. This combines known information about the shape of the seabed, with an autonomous capability that spots anomalies, enabling the AUV to navigate around them and lock on to the pipeline once the danger has passed.

‘All the oil companies worry about the additional costs of deepwater working. BP has many such assets, and the economic advantages for using AUVs are becoming more compelling,’ said Evans.

BP sub-sea engineer Lee Billingham confirmed that the company is extremely interested in the technology, and said that assuming successful testing, AUV systems are likely to be in regular use within the next three years.