Aaron McDougal, Houlder Engineering Director, writes about the challenges facing those stacking drilling units.

We need to re-think the way we look at stacking and re-activating offshore units. It’s not easy to discuss. However, the reality of today’s industry must be faced, and a well-planned lay-up period can place companies in a stronger position in the long run. With detailed preparation and careful execution, a unit can be safely and securely stored in a state ready for rapid reactivation.

The first question should be “how will we re-activate when we need to?”. If you’re not thinking about it like that, then you’d be better off scrapping. It’s rarely a one-size-fits-all solution. A team must be formed who will cover all stages of the lay-up and reactivation. This contains people with an intimate knowledge of the unit – e.g. senior crew, but it should be led by an independent party.

Unit type and age will narrow the options. A jack-up has different unique requirements from a semi-submersible or drillship. Location; water depth, soil type, proximity to quayside. Preservation; trace heat, corrosion inhibitors, desiccants. It also drives the regulatory framework – vessels of different specification, notations and generations can have vastly different requirements to meet.

The duration of the lay-up period affects where you take the unit and how you leave it. For short-terms, it can be cost effective to maintain a “warm” stack (minimum crew to maintain critical equipment). For longer term, “cold” stacking can be more appropriate– completely down-manning, shutting down, preserving systems and sealing the unit. Careful consideration is needed here.

Once a set of basic requirements, plans and procedures are set, stacking locations can be assessed and vetted. It is critical for the Stacking Manager to visit and assess in person. The environment, logistics, security and commercials must all be tightly controlled. Very importantly, appoint a good agent who knows the port, local services and local customs.

On officially entering lay-up status, a class society surveyor attends. In general, this is to ensure the plan is adhered to and the unit is in a safe condition. The operational survey schedule goes on-hold, and a lay-up certificate is issued. For more complex and sophisticated units, this process may be more extensive – it is critical to capture this at the planning stage.

The on-going preservation of the unit must receive the same attention. The temptation to cut costs here will be at the detriment to the speed and efficiency of re-activation. Regular asset condition assessment and active integrity management are crucial. Even though regulators may not take the same interest when laid-up, it is absolutely the wrong thing for owners to ignore this too.

Companies must avoid the temptation of a “quick-win” – getting a rig stacked quickly, cheaply and often poorly. If there’s one thing we all know about oilfield economics, it’s that it is cyclical. Think long-term, and think strategically. Not all units will be worthy of stacking, but for those that are, your future depends on being the first out of the blocks when the whistle blows.