Red Hawk Down: How they made it look easy

The decommissioning of Anadarko’s Red Hawk spar in September 2014 set a number of records. Here, Ryan Kavanagh, the man in charge of the project, tells DecomWorld how planning made perfect

In ten minutes, Red Hawk’s hull had toppled out of site beneath the waves (InterMoor)

It started life as the world’s first cell spar, with a 560-ft-deep hull consisting of seven giant cylinders. It ended life as the deepest floating production unit ever to be decommissioned in the Gulf of Mexico, and the first spar ever to be reefed.

Impressive kudos indeed, but what made its transition to a new life sleeping with the fishes even more interesting was how slick the project was, given that both deepwater decommissioning and floating-structure decommissioning are both somewhat uncharted territory for the offshore industry.

In an interview with Upstream Intelligence, Anadarko’s Ryan Kavanagh explained how the project team, including Anadarko, the regulator, the contractors and other stakeholders spent 18 months ensuring it would look like child’s play on the day.

 

Decommissioning rock-n-roll

The Red Hawk was installed in 2004 in Garden Banks (GB) Block 876, 200 miles offshore in the Gulf to produce natural gas from subsea wells by Kerr McGee, which was acquired by Anadarko in 2006.

The Red Hawk was the world’s first cell spar, with a 560-ft-deep hull consisting of seven giant cylinders (Anadarko)

In 2011 the wells were permanently plugged and abandoned. Anadarko sought opportunities to redeploy the spar, but without success. With its lease on the block set to expire in 2012, the company set out to plan its decommissioning.

The project, which took place over 24 days in August and September 2014, had a number of what you might call true decommissioning rock-n-roll moments.

The most visually arresting was the lifting of the 3,600t topsides, using Versabar’s gargantuan VB 10,000, a crane system mounted on two dynamically-positioned barges that is high enough to slide over the topsides in mid-ocean and strong enough to pluck it off the hull in a single lift.

InterMoor deballasted the hull down to 20 feet of freeboard for the four-hour lift, and giant hooks had been welded into place on the topside deck to give the crane something to grab onto. The VB 10,000 then eased the topsides onto a barge, which bore it for 36 hours to Morgan City, Louisiana for recycling.

Versabar’s gargantuan VB 10,000 lifts Red Hawk’s 3,600t topsides

Topless now, the 560-foot-deep hull was reballasted way back up to 160 feet of freeboard, necessary because the hull was about to make a special journey, and could not be allowed to scrape on the seafloor when it left deep water.

 

An unusual sight

For two days and 70 nautical miles it was towed in that upright position – an unusual sight for any passing marine traffic – until the tugs reached Eugene Island Block 384, a designated reefing site under Louisiana’s Rigs-to-Reefs program.

The hull was deballasted until it rested on the seabed in 430 feet of water. Tugs then pushed it over. Five-foot-diameter holes that had been pre-cut in the cylinders by rope-access workers ensured their flooding in a particular sequence. In ten minutes it had toppled out of site beneath the waves, and the hull came neatly to rest between two platform jackets already reefed on the sea floor.

Red Hawk thus became the first spar to be decommissioned in the GOM, and the first spar to be reefed.

The hull, upright and topless, was towed for two days to the reefing site (InterMoor)

Looked so easy

It all went so smoothly that an observer might think it’s no big deal, decommissioning a deepwater spar. But that would be a mistake.

“The planning effort actually started back in early 2012,” said Ryan Kavanagh, Facilities Engineer, Gulf of Mexico Deepwater Facilities, Anadarko Petroleum Corporation. “The light was at the end of the tunnel then so we started to engage the regulators very early.

“It was a collaborative process to talk about the options that were there for Red Hawk, what challenges existed, what information they would want to see in a one-of-a-kind floating facility removal permit. We worked over 18 months to get a good, safe plan developed, permitted and ultimately approved for execution.”

During the permitting phase, planning rumbled along at medium-boil, but once the plan was agreed things got very busy.

“We kept things at a pre-FEED engineering level where we knew how we were going to do it but also identified some key areas we knew we’d have to dive into, like equipment sizing, procurement, etcetera,” Kavanagh said. “Once we knew our execution plan had been approved, then we dove into that and it became a very time consuming project.”


Structures active in the Gulf of Mexico in water depth greater than 400 ft (1978-2013c).

 

Blowin’ in the wind
Was there anything that kept him up nights as the day approached? Not really, Kavanagh said. They had put the plans through a thorough risk management and hazard identification process, multiple peer reviews, the SEMS requirements for the Gulf of Mexico, and Anadarko’s own management system.

After all, broken down into individual tasks, there was nothing about the Red Hawk project that hadn’t been done before. The tricky part was stringing all the tasks together in a compressed time period, a time period that fell – and this was the bit they couldn’t control – during peak hurricane season.

As it happened, the project got off lightly. Tropical Storm Dolly hit over 2-3 September 2014, just as the team was preparing for the topsides lift, but the storm was contained in the Mexican part of the Gulf, near the Bay of Campeche. Kavanagh said heightened swell caused some down-time but the storm did not otherwise affect the project.

And anyway, the planning heavily factored in hurricane risk: “We knew we couldn’t count on ten or fifteen-day perfect weather windows. We had to break everything down into two or three-day windows,” he said.

“For instance, we had to pre-cut the deck legs, which took over a day for each leg, and then temporarily secured them with clips so that when it came time to make the topside lift it was a quick flame cut. The clips themselves were designed to withstand the loads of a 10-year storm. We had a marine warranty surveyor review them, we had the Coast Guard review them.”

 

Same again, please

Asked for any major lessons learned, Kavanagh said only that planning makes perfect.

“The big lesson at the macro-level is that the plan we followed worked. It was permittable, and technically achievable. We had a good sparing capacity, good contingency plans in place for various things, so that if some what-ifs happened offshore it wouldn’t really impact the project.

“There were some lessons at the granular level to do with equipment but if we had to do it again, from an outside perspective, it would look the same.”

Kavanagh said Anadarko has other spars in the Gulf of Mexico that would be equally complex to decommission, but that they are producing hydrocarbons now and the company is not actively looking at any other decommissioning projects.

When the time comes, however, the future teams will be able to refer back to the Red Hawk experience: “We documented the process very well, leveraged the internal knowledge-bearing tools that we have, so twenty years down the road we’ll know what to do.”