Our research into fully automated dry hyperbaric (high pressure) gas metal-arc welding (GMAW) has led to new ways of connecting and repairing subsea pipelines. This should provide a boost to the oil and gas industry of billions of dollars through increased recovery and production.

Key facts

    • Fully automated dry hyperbaric (high pressure) gas metal-arc welding (GMAW) is used in the remote repair and hot-tap connections (making a connection to an existing pipeline that is in operation) of the expanding number of deep-sea oil and gas pipelines.

    • The world’s first fully remote application of hot-tap production took place in August 2012.

    • In September 2015, Statoil and partners realised the world’s first subsea compression on the Åsgard field in the Norwegian Sea. This saw compressors installed on the seabed, instead of on a platform, improving recovery from the Mikkel and Midgard reservoirs by more than 300 million barrels of oil equivalents.

    • The new technology will financially benefit oil and gas companies, by billions of dollars, through increased production and recovery from existing oil fields which will hopefully lower the cost of energy production. It should also make it easier to maintain pipelines, as well as providing the ability to repair subsea structures at great depths to avert, or deal with, underwater man-made disasters.

  • Funded by Statoil.

Impact of our research

Our long-running research into fully automated dry hyperbaric (high pressure) gas metal-arc welding (GMAW) has led to new ways of connecting and repairing subsea pipelines. This process allows pipeline operations in increasingly deeper waters, making it possible for the development of previously inaccessible hydrocarbon reserves. We researched and developed the technology for water depths of up to 2,500m before industry then further developed and qualified the technology.

GMAW is used in the remote repair and hot-tap connections (making a connection to an existing pipeline that is in operation) of the expanding number of deep-sea pipelines. The world’s first fully remote application of hot-tap production took place in August 2012, and Statoil and partners realised the world’s first subsea compression on the Åsgard field in the Norwegian Sea in September 2015. This saw compressors installed on the seabed, instead of on a platform, improving recovery from the Mikkel and Midgard reservoirs by more than 300 million barrels of oil equivalents.

Why the research was commissioned

The continuous increase in demand for oil and natural gas has resulted in sustained growth of offshore oil and gas production. Offshore crude oil production can be broadly classified in three categories based on the depth of water – shallow water (up to 400m), deep water (400-1,500m) and ultra-deep water (below 1,500m).

The rate of offshore production of oil and natural gas growth was on the rise from the mid-1960s until the mid-1990s when offshore production reached a plateau. This was due to the depletion of fossil fuel in the shallow water region as deep-sea exploration showed a significant growth during that period.

Dry welding in deep water is complex as no human intervention is allowed by legislation. Also, the behaviour of the arc under high pressure would be different and gas tungsten arc welding developed for diver-assisted welding in shallow water, below 180msw (metres of salt water), would not be suitable for deep-water application.

Why Cranfield?

We identified that fully automated dry hyperbaric welding for deep-water applications was going to be a major requirement for the sustainability of UK and world fossil fuels. Deep-water hydrocarbon recovery had grown steadily since 1990 to become a significant fraction of offshore oil and gas production. This production is likely to grow significantly over the coming years due to depletion of reserves in shallow waters.

We established a unique facility, still the only one for academic research, to enable the study and development of arc welding processes, in all positions, up to a gas pressure of 250 bar, equivalent to 2,500m water depth. Then, using this facility, we conducted extensive research and developed considerable understanding into the different power source and arc behaviour, in particular gas metal arc and plasma welding, at high pressures.

Facilities used

Hyperbaric welding chamber (maximum rated pressure 250 bar) and associated gas pumping and recirculation facility.