The Well Enhancer Helps Industry Successfully Test Well Cap Deployment

21 October 2011

Aberdeen-based Helix Well Ops UK (Well Ops), a business unit of Helix Energy Solutions Group (Helix ESG), was at the centre of a recent exercise that successfully tested the UK oil and gas industry’s ability to deploy a well capping device.

The purpose of the Emergency Equipment Response Deployment (EERD) exercise was to simulate the logistical process of responding to a well control incident. This involved transporting a well capping device, loading it on to a vessel and lowering it over the side before fixing it to a specially-built simulated well on the sea floor.

Led by the Oil Spill Prevention and Response Advisory Group (OSPRAG), the exercise was conducted from the Well Ops vessel the Well Enhancer at a site in block 206/4, around 75km north-west of Shetland.

Performed from the deck of the 132-metre long well intervention and diving support vessel, the 10-day operation demonstrated how the industry would handle a well blow-out and resultant oil spill.

The exercise was part of the UK oil and gas industry’s response to the 2010 Gulf of Mexico oil spill. Well Ops was able to implement best practice learnt by its parent company Helix Energy Solutions Group, which had played a key role in the response to that incident.

Launched in 2009, the Well Enhancer provides remotely operated vehicle (ROV), diving and well intervention services. It features a 150-tonne multipurpose tower fitted with passive and active heave compensation (AHC) and is capable of deploying wireline, slickline and coiled tubing (CT) tools to a depth of 1,000m. The vessel also features kill pumps, an intervention lubricator control system and a 100-tonne crane which is operational to 600m.

Following arrival at the test site, the first stage of the exercise involved deploying a specially-built landing base onto the seafloor at a depth of 300m, in order to accurately simulate a subsea well. This was deployed over the side of the vessel by the onboard 100-tonne main crane. Having recreated the subsea environment, ROVs were deployed to distribute a non-toxic fluorescent dye which replicated the use of subsea oil dispersant in a live well control situation.

The next element of the EERD process saw heavy-duty cutting shears being deployed to sever subsea marine pipes. The two choke lines and one riser were cut using an ROV-mounted saw and the cut sections recovered to deck. This process is necessary to clear the riser out of the way and allow the cap to be landed and seal off a blown-out well.

The 40-tonne demonstration cap was then lowered 300m by wireline, run from the AHC multi-purpose tower, through the Well Enhancer’s moon-pool and landed onto the simulation well. AHC keeps the load at a fixed position relative to the seabed and avoids the vessel’s motion being transferred to the load. ROVs were then used to lock the cap onto the base and activate the valve functions. The trial used a device that was of similar size and weight to the actual well cap which was launched at Offshore Europe 2011.

On completion of the exercise, all the equipment, including the landing base, was recovered back onto the deck of the Well Enhancer and no negative effects to the marine environment were detected.

Steve Nairn, Well Ops’ regional vice president of Europe and Africa, said: "The well capping device is a major and important piece of equipment for the UK oil and gas industry. This test has demonstrated the industry’s ability to respond to a major well control incident and underlined the capability of light well intervention vessels.

"The UK has not experienced a blowout for over 20 years and Well Ops is committed to working with the industry to ensure we are fully prepared should such an incident arise, but also to prevent such incidents in the first place. We are glad to have provided an effective contribution to this successful exercise.”