The abandonment process in the North Sea is subject to many legislative and regulatory requirements. How can we abandon efficiently and ensure that we comply with these important requirements?

The long list of regulations can be daunting for operators. Some even delay abandonments longer than they would prefer, because they are concerned about meeting regulations.

It’s quite possible to manage successful—and compliant—P&A campaigns with thorough planning and evaluation. If you think of abandonment as a campaign rather than a series of discrete events, you can manage your risks with contingencies and even improve efficiency.

Schlumberger maintains close relationships with industry and regulatory bodies. Our P&A engineering advisor is part of the Oil & Gas UK (OGUK) work group that helps define the well abandonment guidelines. This involvement gives a very in-depth understanding of what the industry is looking for and what Schlumberger can deliver to ensure integrity of operations.

For an operator’s campaign, we can evaluate techniques and services that may be able to bring improvements and efficiencies to a campaign of work.

Additionally, being able to define the risks and associated mitigation in the subsurface, well hardware, and surface facilities can greatly reduce costs and exposures. Given our wealth of subsurface expertise and analysis tools, along with our engineering depth and numerous projects experience, we are well placed to work with our customers to robustly prepare and optimize work plans.

When should operators consider their well abandonment plans?

This is a great question, and one that more and more North Sea operators are asking as they face end-of-life planning. All too often operators completely disconnect production from abandonment, as if one day the asset is profitable and the next day it’s plugged. Of course, that’s not how it works. You see production declining, but that abandonment planning process is going to take some time, especially if you are designing an integrated campaign to gain the efficiencies you want.

So ideally, you want to start thinking about abandonment some time before you expect to actually abandon wells, and certainly while your asset is still producing. That way, you can evaluate your stock with a view to work over the best candidates and keep them producing while you are abandoning the less-viable wells. This extends the profitability of the better assets while gathering information about the whole campaign and helps mitigate risks moving forward.

There is a significant opportunity to look at late-life asset management in conjunction with planning for abandonments.

Schlumberger has subsurface and engineering capabilities to evaluate asset well stock with a view to working over wells to improve production, while at the same time gaining updated information on these wells to plan the abandonment campaign. Not only will this extend profitability of the asset, but it will ensure that the abandonment planning is more robust, mitigating the risk of the unknown.

A lot of these assets have decaying above-water infrastructure. An operator may not want to reinstate the platform rig or hire a jackup. What can be done riglessly?

Depending on the well architecture and the complexity of remedial work required, many abandonments can be executed under a true rigless regime. Examples of this include deploying digital slickline, coiled tubing, or both.

For complex wells, there is an opportunity to execute a significant portion of the abandonment without a rig, such as a plug and lubricate campaign of work. When a “rig” is definitively required, there are several options that would remove the need for either refurbishment of a drilling package or mobilizing a mobile drilling unit. Through the merger with Cameron, Schlumberger has the capability to design and deliver modular systems, which can cover operations ranging from simple pulling units to abandonment units able to cover full scope. Through our portfolio of services, we can offer fit-for-purpose P&A solutions for a wide number of applications. For example, in the Southern North Sea, digital slickline combined with small batch mixers, was used for full P&A operation and in the Central and Northern North Sea has been run simultaneously with rig-based operations to conduct rigless batch operations that reduce overall time and cost.

Schlumberger is actively working on developing technologies that will ultimately negate the need to use a rig-based approach in all but the most challenging of scenarios.

How does Schlumberger approach the challenge of abandonment of subsea infrastructure?

We also maintain strategic alliances such as the Subsea Services Alliance (SSA) with our partner Helix Energy Solutions Group (ESG). The SSA combines the strength of Schlumberger and OneSubsea, a Schlumberger company, to provide a wide portfolio of subsea well intervention technologies and decommissioning services enhanced by Helix ESG’s comprehensive marine support, project management operational expertise and capabilities. An example of the benefit of working with such an alliance is the ability to provide light well intervention vessels for subsea P&A and perform intervention-based work scopes upfront, which can sometimes eliminate the need to bring in a mobile offshore drilling unit (MODU). The SSA between Helix ESG and Schlumberger, which has been in effect for several years, has successfully executed many intervention and abandonment scopes in the UK, Gulf of Mexico, Asia, and West Africa.

How does an operator meet industry goals to reduce decommissioning cost by 35%?

An integrated campaign-based approach to abandonment is one of the best ways to manage costs and risks in abandonment. If you think of well abandonments as a set of discrete services rather than a holistic, integrated campaign, you will miss out on a lot of efficiencies.

Our integrated approach to work brings significant added benefit by provision of a single-sourced, project-managed package.

The benefits of this are to enhance the ability to evaluate the work-scope requirements and risk on a wider basis, introduce the ability to streamline resources, potentially including multiskilling of personnel within Schlumberger as well as other contractors, and from a risk perspective introduce more aligned commercial models to drive performance. When this is applied across a full decommissioning campaign, it becomes much more cost efficient, helping to meet the OGUK objective.

This alone will not be enough to meet the demands of the industry. Schlumberger is continuing to evolve and develop technologies in-house and work with subject matter experts and the industry to introduce a step change in how abandonment will be executed in the future. Watch this space.