Understanding Energy: Decommissioning

While all observers are focused on coming first oil, offshore production is a long-term activity that will stretch decades. Though it is still early days, there are always longer-term activities that are important to consider.

One such activity is “decommissioning” — the careful process of dismantling oil production equipment, capping wells and other key steps in returning a drilling and production site to its previous natural state. This is the final step of the oil production cycle and happens when oil wells are depleted from years of production. This will likely be two to four decades down the road for Guyana.

The goal of decommissioning is to safely take tools and infrastructure used in oil production offline. That covers a lot of activity depending on how and where the oil is produced. In Guyana’s case, it could include everything from sealing off subsea wells to cleaning up any equipment left over at shorebases.

Given Guyana’s track record of 13 successful discoveries so far, the overall production in the Guyana Basin will long outlast individual wells. In regions like the North Sea and the Gulf of Mexico that have long histories of production, this is already the norm. Wells are capped once individual deposits are depleted and the rigs and production equipment are simply moved to a new site.

Decommissioning and exploration even happen side by side, since an oilfield can contain many separate deposits of hydrocarbons at different depths and in different spots nearby. Oil wells are also normally drilled years apart so each one will reach peak production and eventually be depleted on its own timeline.

The fact that Guyana’s oil deposits are in extremely deep water far offshore has implications for the decommissioning process. On one hand, it makes the process more technically challenging from an engineering standpoint. However, capping wells in deep water is a common industry practice and major companies and their contractors have long histories of doing safely.

On the other hand, the depth of Guyana’s reserves does come with some advantages. It is not directly near fragile onshore ecology, and the wells’ placement in deep waters also reduces any threat to reefs or other shallow water ecosystems.

In Guyana’s case, there will also be no rigs to remove. The oil will be produced by floating production storage and offloading (FPSO) vessels rather than the kind of permanent oil platforms used in shallow water. FPSOs have the ability to sail away when the field is depleted. The subsea system of pipes and control systems the FPSOs attach can be removed and taken away by surface vessels.

It should also be noted that this kind of decommissioning work often brings a new surge of economic activity, since many of the same skill sets are needed for both decommissioning and construction.

An example of this is in the North Sea, where production is declining after decades of successful deep-water oil extraction. A new industry is emerging around dismantling, scrapping and repurposing rigs and other equipment.

That drives demand for welders, construction workers, and other types of skilled workers.
Sites left behind onshore, such as supply depots, hangars and shore bases, can often be repurposed for use long after the industry leaves. It’s common for companies to negotiate with local governments to provide a repurposing plan to convert old sites into a new form that can serve an economic or social purpose, like a new park, arts space, or an industrial facility for local small businesses.

Although this kind of work won’t be taking place here for many years, it’s worth understanding the full life cycle of oil production, now that Guyana is on its way to becoming a major producer.

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