Making a step change

Elaine Maslin reports on two new vessels and a semisubmersible from Helix Well Ops due out in 2017-2019, which aim to make a step change in operational efficiency.

The Siem Helix 1’s back deck spread from Osbit.Image from Helix.

Helix Energy Solutions has three new vessels coming into the market, the Siem Helix I and 2 this year and the Q7000 in 2019. They have all been designed building on Helix’s nearly 30 years’ experience in the well intervention space – plus a dollop of a northeast England engineering expertise.

Each new unit is being fitted out with a new-design intervention tension frame (ITF), blowout preventer (BOP) storage and maintenance tower, moveable decks and gangway access system.

Together, these will enable Helix to do something significant – i.e. change between coiled tubing and wireline operations without the need to disengage from the wellhead. This is an industry first. Before, a reconfiguration would have been required between operations. Staff will also no longer have to use so-called man-riding winches or cranes to access the equipment for maintenance, making the system safer.

Both moves are set to reduce downtime and increase staff safety. “The ITF is designed to increase efficiency and safety,” says David Carr, vice president – Commercial, Helix. “It will take all man riding out of the process and provide a walk-to-work system so staff can get right up close to heave compensated equipment that is bouncing up and down, without having to wear riding belts. It is a real step change in use of technology to increase efficiency and safety in operations.”

The 158m-long, 31-beam, DP3, Salt 307 WIV design Siem Helix I and 2 were completed at the Flensburger shipyard in Germany (owned by Siem Industries) in 2016, and will be chartered from Siem Offshore (part of the Siem group). Both will work for Petrobras, under four-year initial term contracts, offshore Brazil, with the Siem Helix I starting operations in Q2 and the Siem Helix 2 due in service later in the year.

Both vessels have accommodation for up to 150, a Huisman multipurpose tower (MPT) and a 250-tonne, down to 3000m water depth crane. The Q7000 is being built by Sembcorp Marine’s Jurong Shipyard in Singapore and is due in service in 2019. Once complete, the unit will also have a Huisman MPT.

Northeast England engineering firm Osbit designed a string of new systems for all three newbuilds, having been initially awarded the ITF contract in March 2015. Osbit had previously worked with Helix on its Seawell refit and designed some other equipment – umbilical guide wire system and ROV launch and recover systems – for the Q7000.

“Helix came up with a brief outline of what they wanted,” says Steve Binney – Osbit engineer and project owner. “The industry used to have someone on the moving equipment on a man riding crane. It was probably something that started as a one-off but it took a company like Helix to be building new vessels to start thinking about how to move away from that.”

Brendon Hayward, Osbit’s managing director, says: “In parallel to that, the market is driving people to look for efficiencies and competitive advantage. Because the oil prices have dropped, no one has money, so we need to be more efficient. The whole idea is to make the process safer, better, faster and cheaper. The result is a step change.”

Hanging off each vessel’s Huisman heave compensated MPT, the ITFs form a tensile connection between the well riser and the vessel’s handling equipment during well intervention operations, while also facilitating safe access into the riser. The entire ITF effectively stays stationary as the vessel moves, so that subsea equipment, including the riser, isn’t damaged.

In normal run of operations, the riser sections, with subsea stack attached to the bottom, would be built down to 5-10m from the seabed. Then the ITF would be attached, active heave compensation (AHC) mode initiated and the stack connected to the well. The gangway would be connected before going into AHC mode.

To this is added the maintenance tower, with a 120-tonne crane, to build and service the stacks, and pivot for connecting to the ITF while active, and the movable deck, which slides to the well center and from which the iron roughneck and third party equipment can be deployed. Beneath the moveable deck is a well center operations equipment storage space. Both add a level of safe access for operations maintenance that has not existed before, Osbit says, as well as providing working and storage areas, all while not getting in the way of the riser handling cat walk.

The ITF enables Helix to switch between coiled tubing and wireline operations, without detaching from the well, removing the need for tool changeover, and allows for operation in worse weather conditions. Each ITF has three platform access levels, supported by Osbit-supplied BOP maintenance and storage towers and moveable decks. This allows on-board equipment to be moved into its working position quickly and easily via three-plane movement skidding systems, rather than being lifted into position. The systems were also designed to support a full range of third party equipment and can be configured for different tooling options.

Each ITF stands at more than 20m-high and weigh about 100-tonne, with a 600-tonne safe working load and meets EX BSEN13463 standard.

Integrating the systems was an important part of the work, Hayward says. “Often subsea systems can be over looked and don’t often work that well together,” he says. “In this example, Helix brought us a problem, which we worked with them to solve. But in a position where we can look at all the subsea system integration.”

Accommodating and packaging all the necessary equipment subsystems and third party equipment was a challenge. To accomplish this, the ITF’s skidding systems were developed. A design that could handle a vast range of third party equipment varying in size, weight and shape was created. 3D design software, used throughout the design, helped ensure there would be no equipment clashes during skidding operations and that equipment could be secured.

While all three ITFs look similar from the outside, and are, the internal will differ on the Q7000, with different level platforms, etc. The equipment layout on the Q7000 will also tend to be more stable, whereas the Siem Helix I and 2 would be more adaptable to meet Petrobras’ needs, which meant the design on the Q7000 could also be more stream-lined, Binney says. But, should the ITFs need to be moved to a different vessel with different internals, they could (and were also designed to be road transportable).

Osbit was also able to work in a unique way with Helix. “We started out with a problem,” Hayward says. “We worked from that to find what was feasible and what was the best solution, then optimized that to get the best weight, which is quite rare. Normally someone gives you a weight budget.”

This was partly enabled by Helix doing initial design studies with Osbit, to find a rough idea of the weight of the system, then designing the vessels around that weight. “The weight hasn’t really varied from the initial front-end engineering studies,” Binney says.