With cost-effective well intervention and decommissioning major priorities for the North Sea, rigless technology offers a route to realising greater efficiencies. Wireline learns more from expert Helix Energy Solutions.
Subsea wells are a paradox – at least according to Helix Energy Solutions Group’s David Carr.
They are in general among the most expensive wells in the world to drill, often in the harshest of environments and most remote areas of the world. “The paradox,” Carr explains, “is that although they are typically very prolific, they generally have the lowest recovery factor, primarily due to the fact that intervening on such wells is incredibly expensive, as it traditionally requires a large deepwater drilling unit to gain well access for such work.”
The topic is a timely one, not just as the industry begins in earnest to grapple with the extent of decommissioning on the UK Continental Shelf (UKCS) – where subsea wells make up around 40% of the well stock expected to be decommissioned over the next decade – but in extending field life through workovers as well. Reducing the complexity and expense of subsea intervention operations is therefore critical to lowering operating expenditure and improving recovery over the long term. Rigless well intervention, in which smaller vessels and light well access technology are used to perform well operations, avoiding the need for a larger drillship or rig and associated riser pipework, is a key enabling technology.
Helix Energy Solutions Group (ESG) is a pioneer in this field. The company made its entrance into the UK North Sea when it performed the world’s first riserless well intervention operation from the dive vessel MSV Seawell at the BP-operated Magnus field in 1987. This ground-breaking project paved the way for a whole new industry to arise – developing vessels, equipment and techniques to economically enhance, repair and ultimately decommission subsea wells.
Following Helix’s advances in the light well intervention field, companies like TechnipFMC, in partnership with Island Offshore and Altus Intervention, have expanded the use of riserless light well intervention vessels (LWIV) using similar technologies. Helix however, has remained at the forefront, and still operates two vessels in the UK with unique characteristics – both the MSV Seawell and Well Enhancer LWIVs are capable of conducting well interventions using riserless technology while simultaneously performing saturation diving operations, an activity that is often essential with older subsea tree infrastructure.
Carr, a senior vice president at Helix Well Ops UK, adds: “Many of these North Sea trees have been producing since the 1980s and in many cases are past their design life. Working them over with a rig would mean landing over 150 tonnes of [blow-out preventer] BOP and marine riser onto them, which is generally impossible. A riserless package – weighing from just 30 tonnes – combined with diving support is often the only way to maximise economic recovery from these older assets.”
“This is a culmination of the technologies and learning from across the world, distilled into a unit that is conceived and specified for the North Sea.”
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Although its name may have been made in the North Sea, much of Helix’s recent expansion has been concentrated in the US Gulf of Mexico and Brazil. It was this environment that spurred the development of its Intervention Riser System (IRS) for deepwater operations, where asphaltene production from high-volume wells frequently requires the deployment of coiled tubing to enter wells to clear blockages.
Deployment of the IRS also led to the development and construction of the world’s first dedicated rigless intervention vessel, the Q4000 (the same vessel that would later cap the Macondo well following the Deepwater Horizon disaster). This in turn led Helix to build (to contract) Brazil’s first dedicated rigless intervention vessels, the sister ships Siem Helix 1 and 2, currently under a multi-year contract for Brazil’s Petrobras. The national oil company recently awarded Helix with the ‘2018 Supplier of the Year Award for Operation of Maritime Rigs’ – a notable achievement for the team in the first year for which they were eligible.
While Helix has expanded global operations, the Seawell and Well Enhancer have remained stalwarts of the North Sea sector, Carr notes, the former undergoing a £58 million refit in 2016. More than 30 years on, the innovation that started at Magnus in 1987 will come full circle when Helix intends to introduce its new riser-based intervention vessel, the Q7000.
“This is a culmination of the technologies and learning from across the world, distilled into a unit that is conceived and specified for the North Sea,” he continues. “We created a vessel that can take on the well access challenges of the west of Shetland zone, as well as being able to deal with central North Sea environments down to just 80m.”
The approximately $500 million, semi-submersible vessel represents a strategic investment by Helix in the UKCS, where it will be deployed to address the specific challenges posed by maximising economic recovery (MER) and decommissioning cost reduction.
Built at Sembcorp Marine’s Jurong yard, the vessel’s specifications also reflect a combination of the company’s experience from North Sea operations and riser-based operations in the US Gulf, as well as the topside efficiencies created for Brazil monohull vessels which allow for very fast changeovers between work modes. “For good measure, we built this semi-submersible on ship-shaped pontoons so that she can transit at 10 knots, allowing us to support seasonal work in West Africa as well,” Carr adds.
Flexibility would seem to be the guiding principle of the Q7000’s development. Capable of working in depths from 80m up to 3,000m, the unit also features twin ROV support with heavy weather launch and recovery systems, a multi-palette skidding system on deck (which means no crane lifting is required to carry out routine operations) and DP3-class positioning, all of which open greater operational windows in terms of weather conditions and sea state. The ability to switch between coiled tubing and wireline quickly also reduces downtime between interventions, while a riserless openwater abandonment module (ROAM) will enable well decommissioning without the need for a full-bore riser in many cases.
Helix anticipates all these capabilities will equal greater cost savings and more value for UK operators. Carr points to a recent case study from the Gulf of Mexico, in which the Q7000’s sister vessel Q4000 completed a 13-well campaign for a large operator over a period of 135 days. In this project, Helix performed a wide array of MER and decom work across seven fields, including three zonal isolations, two coiled tubing clean-outs, two chemical treatments, a milling operation, five stimulations and two abandonments.
“Efficiency was added to this operation by ‘hopping’ the IRS well access package subsea, from well to well – a total of 41 miles,” he says. Helix acted as project manager for the operation – which necessitated 44 regulatory submissions – but resulted in over 40,000 barrels per day of additional incremental production achieved across the project, as well as 20,000 bpd of increased water injection capability.
While beneficial, in this instance the usual metrics of efficiency and cost are secondary. Carr stresses that using a vessel like the Q4000 made these kinds of production-enhancement operations economical. “The work, and the increased production, would never have happened without this technology,” he notes. In that regard, they are expected to be a key asset as operators and the Oil and Gas Authority (OGA) seek to achieve MER.
Currently preparing for its first operation offshore West Africa, the Q7000 is due to launch officially in Q3 2019. Although Helix has yet to announce firm contracts, the vessel is expected to make its way to the North Sea sometime in 2020-21.
“Shut-in wells, stranded reserves and of course maximising economic recovery are all very much plans for the coming decades.”
The enhanced capabilities of vessels like the Q7000 reflect Helix’s wider business strategy. As CEO Owen Kratz adds: “Helix is a solutions provider, not a vessel and equipment provider. We set out to become the company that can provide all forms of subsea well intervention. So now, unlike other companies, we can offer our clients the intervention solution they need, not just the assets and equipment we have.”
Beyond its established work in oil and gas, the company has also developed a presence in the offshore renewables industry. Leveraging its subsea trenching expertise, Helix has become a major player not just in the development of offshore windfarms, but also in “power from shore” electrification initiatives, aimed at reducing gas flaring and, where possible, lowering the emissions intensity of offshore production and enabling the wider energy transition.
Helix has extended its innovative approach to commercial models as well, actively moving away from ‘fee for service’ day-rate contracting to new ways of unlocking value through what it calls ‘creative contracting.’ “We may not be the cheapest, but we’re always the lowest cost” quips Carr. “We are prepared to stand by our skill and experience, and that allows us to enter into different commercial models such as performance contracting, shared risk and reward, and even qualified lump sum operations.”
This extends to decommissioning and late-life operation too. The combination of service company with late-life operator – a model previously employed by Helix’s former E&P subsidiary – also presents a route for future work. Having all the tools and equipment at hand to enhance the production of subsea wells grants it the flexibility and capability to carry out interventions and ultimately decommission wells on its own schedule, lowering costs for all stakeholders.
This approach was revived earlier in 2019 when the company acquired Marathon’s four-well Droshky field in the Gulf of Mexico, and Helix is seeking similar models on the UKCS. While there are no official work programmes as yet, Carr confirms it is “something we’re actively pursuing in the UK.”
With the Q7000 now set on its path to the North Sea, Carr says that Helix is looking forward to exercising these enhanced capabilities alongside its existing riserless intervention assets to help address the unique challenges of the basin. “By offering low-cost operations, combined with creative contracting options, we aim to be a driver of the Vision 2035 goals of the OGA in the subsea segment,” he adds. “Shut-in wells, stranded reserves and of course maximising economic recovery are all very much plans for the coming decades.”