Doubling Down on Decommissioning

By Felicity Landon

Mammoet project manager Martin Alards shares his expert insight into the transport company’s critical role in one of the world’s most ambitious gas well closure programs – the SITURN initiative in the Netherlands.

From Issue 1, 2025 of Breakbulk Magazine.

(5-minute read)

The Netherlands is embarking on one of the most ambitious gas well decommissioning programs the world has ever seen. With 800 wells, 350 locations and 1,750 km of pipelines slated for closure over the next 10 to 15 years, the SITURN initiative represents a new frontier in dismantling decades of fossil fuel infrastructure.

Overseen by NAM, the Shell-ExxonMobil joint venture exploration and production company, in partnership with Arcadis, WellGear and equipment giant Mammoet, this huge effort is setting a precedent for safe and efficient well closure operations – and capturing the attention of the energy sector.

The project will see the decommissioning of every closed onshore gas well in the Netherlands, including the Groningen gas field wells first discovered in 1959. Mammoet’s role is to provide the critical logistical and engineering support for this massive program.

NAM has been producing Groningen natural gas since 1963 but the Dutch government ordered its closure and production stopped at the beginning of 2024. Groningen gas production undoubtedly brought prosperity to the region and the country, but not everyone is sorry to see it shuttered.

Over the years, residents living above the gas field have endured earthquakes caused by gas production – the most dramatic being in 2012, when an earthquake of magnitude 3.6 on the Richter scale hit the area near Huizinge.

A NAM spokesperson said that while the closure of the Groningen gas field was government-ordered, closure of the other fields has been for technical or economic reasons, and not linked to energy transition. “On the contrary, if there is not sufficient energy produced through sustainable sources, gas – especially gas produced from in-country sources – has a role to play in the transition to a new energy system,” the spokesperson said.

Global Intrigue

Nevertheless, as the energy transition gathers pace, we can expect to see more well closure operations around the world. The oil and gas industry is “very intrigued” by this project and its execution in the Netherlands, said Martin Alards, Mammoet’s project manager, not least because decommissioning a well is often more challenging than constructing one.

The NAM program is one of the biggest gas well closure projects in the world and closure of the first well began in May 2024. Mammoet’s scope is to coordinate and oversee onsite preparations before the arrival of WellGear’s P&A (Plug & Abandonment) hydraulic workover unit, which fills the gas wells with cement caps to shut them in. The equipment itself is electrically driven, to reduce both the carbon and noise impact of the project.

Mammoet is managing the transport, site preparations, assembly and disassembly of the P&A unit as it ‘visits’ each location, overseeing all road and onsite logistics. The 180-ton P&A unit and peripheral equipment, including pumps, waste tanks and accommodation units, amount to about 50 truckloads.

The components will be moved to each location on conventional trailers, pulled by prime movers. The unit will then be assembled and disassembled using mobile cranes with capacities of 100-230 tons. Mammoet is deploying trailers and mobile cranes, including a 450- ton mobile crane for “well hops,” where multiple wells are found in one location and only the WellGear unit needs to be repositioned.

While this is not the biggest project Mammoet has ever taken on, globally speaking, Alards said: “In this particular market segment – gas well closure – it most definitely is.”

He described the project as a “first“, explaining: “We have been active in the oil and gas industry for many, many decades, of course, but the closure of wells and all the work related to that represents a different challenge.”

Safety Drawings

Mammoet is supporting WellGear with rig layout plans to determine how the parts and equipment will be stored at each location before assembly begins. It is also assisting with safety drawings and location safety plans, and its engineers are providing guidance on whether civil works are needed to create space to accommodate the equipment in some of the more remote locations.

Alards said: “The operations we execute for this particular project suit us perfectly. Cranes and transport are our daily business, after all. The site preparations for this kind of project are different but with the help of subcontractors, the project has run smoothly.”

A decade or more is a long commitment – will there be times in between when nothing is happening, or is this continuous work over the coming years? And what does that mean for resourcing and replacing equipment?

Alards explained: “The scope of work is to be executed continuously for the coming period. Equipment that is used is being replaced according to the timescales it usually would be, under Mammoet’s routine maintenance protocols. The resources required will be monitored during the upcoming years and replenished as needed.”

The 350 locations involved are all around the Netherlands – the majority in the northern provinces, with another large cluster in the west. The biggest challenge, said Alards, is that the scope of work for Mammoet can become a 24-hour-aday, seven-day-a-week operation. “We are not continuously on site and so, for example, when a rig move has to take place, the start time can occur at any given date or time, at relatively short notice,” he said. “This is the nature of the work.”

Up to this point, only one P&A unit is in use – but Alards said it’s possible that this might change. “For a well-to-well move – a location with multiple wells, where we hop from well to well – we manage to move in under 24 hours. When we must execute a site-to-site move, from one location to another, we move in under 48 hours. So the longest time the P&A unit is not in operation is 48 hours.”

If technology moved on to the point that WellGear changed its strategy, Mammoet would “certainly team up with WellGear to ensure that together we will still offer the strongest strategic plans for the project.” said Alards. “We of course always try to improve on our services, so whenever we will see an opportunity to improve, we will try to implement that.”

Track Record

It’s notable that Mammoet worked with WellGear from 2019 to 2023 on a successful 76-well closure campaign. Alards reflected: “The experience, dedication and safety of execution in our operations were pivotal, I believe, to our customer choosing Mammoet. Also the drive to always be better and more efficient during the next execution is the spirit of all parties involved.”

He added: “We are not the only lifting and hoisting company in the world that can execute these operations, of course. However, with the history and knowledge we have built up in the past couple of years, we are most certainly a company that has the advantage of an experienced crew with detailed knowledge of the techniques needed to pull this kind of work off.”

Noting the global oil and gas industry’s interest in the project, he said: “Since WellGear and Mammoet are global players, we can deploy similar techniques as part of other well closure campaigns worldwide.

“This is a significant project for Mammoet. It is the biggest gas well decommissioning program in the Netherlands, even the world. The Netherlands is leading in these kinds of operations and, with the world’s energy markets transitioning quickly, it is likely more countries will follow.

“Working with WellGear gives us the unique opportunity to take our combined approach to efficient P&A operations further – not only in the Netherlands but worldwide.”

Mammoet will be exhibiting at Breakbulk Middle East 2025 on Feb 10-11 in Dubai.

PHOTO CREDIT: Mammoet