Neat intervention

Applying university research to an industry challenge has helped create new solutions for Aberdeen’s Hydrasun. Elaine Maslin reports.

Interventor characterization testing at University of Strathclyde.Photo from Hydrasun.

When Hydrasun set out to take well intervention hose technology to a new level, its aim was to develop a product that provided operational efficiencies and cost savings over currently available flexible conduit systems.

Hydrasun thinks it has not only done that, but, thanks to help from researchers at the University of Strathclyde, the hose will be able to support both its own weight and that of other equipment, such as a distribution manifold.

The new 5000 psi-rated 2in hose, named “Interventor,” is virtually neutrally buoyant, light weight, and has a small minimum bend radius compared to other fluid transfer technologies used in well maintenance activities. The hose is un-bonded in structure with aramid reinforcement. It has been designed to be used for fluid injection, such as methanol or acid, on subsea well intervention campaigns, or for dispersant, in the case of a subsea blowout, and most commonly from light well intervention vessels.

“The main driver from operators is for economic well intervention technologies,” says Ben Coutts, director, engineering and research and development, Hydrasun. One example of how Interventor can deliver benefits over current surface to subsea fluid transfer methods, is instead of having to deploy a hose on a cable or wire rope, in order to provide the required level of tensile strength, which means manually clamping it to the cable or wire as its deployed, the hose is itself load-bearing – up to 1.5-tonne with 3:1 safety factor, Coutts says.

Because a separate support cable is no longer needed, less equipment is required onboard and deployment/retrieval of the hose is both safer and quicker.

Interventor comprises a nylon inner liner, aramid reinforcement layers, and an outer polyurethane protective sheath. An empty section weighs 3.2kg/m in air and 5.38kg/m in air filled with seawater. Submerged, and filled with seawater, it reduces to 0.2kg/m.

Because Hydrasun uses aramid for strengthening, the hose itself has no metallic parts, Coutts says, just high fatigue resistance without corrosion.

The materials used means the hose has a small minimal bend radius, which means it can be loaded onto small drums, and is able to operate at temperatures from -40° C to 72°C. To maintain the small bend radius between sections, Hydrasun had a flexible, high pressure articulated joint developed by a supplier to connect the up to 700m-long hose sections. But, it was the hose’s load bearing strength, confirmed during testing at the University of Strathclyde that has given it additional functionality.

Hydrasun was introduced to the university by the Oil & Gas Innovation Centre (OGIC), a new UK body to match industry with academia, which the firm helped set up. “When the requirement for materials characterization was needed Hydrasun came to us,” says Ian Phillips, OGIC’s CEO.

Five universities provided proposals and Strathclyde was selected. “What’s significant is that it is not a traditional oil and gas industry related university,” Phillips says. “Strathclyde has been one of the most responsive of the universities taking part. The principal wants Strathclyde to be the MIT of the UK and they do have a very industrially focused approach to the world.”

By working with a university through OGIC, Hydrasun secured 50% funding for the research. The university, through the project, also gains material for its research projects.

Initially, testing to destruction was performed at Lloyds British in Scotland, with 3.5-tonne load followed by successful hydrostatic tests. Then, at Strathclyde, more complex characterization tests were performed, including static and dynamic load testing, load elongation, cyclic testing, loading under pressure, bending with compression, bending with tension and combinations of the two, etc.

“Minimal failure loads were established, at 5.7-tonne, on a worst case scenario with the hose unpressurised,” Coutts says.

An initial 110,000 cyclic fatigue test (equivalent to 19 days continuous service offshore Africa) was performed, cycling between 1-2-tonnes with no degradation of the hose, followed by a successful hydrostatic test at 7500psi.

“This was a key piece of work,” Coutts says. The end result has been operators that now have shown interest in running long-term tests. Hydrasun plans to continue development and testing of Interventor in preparation for commercialization by December 2015.