Offshore Decommissioning

I’ve been thinking on this concept of alternative oil rigs decommissioning since 2016. For the moment,  I couldn’t find ways to fund and implement it, but in 2017 I tutored a couple of great students from Politecnico di Torino (Davide Iannici and Filippo Laplaca) to develop a proposal for an alternative decommissioning of a ENI platform in the Adriatic Sea for their Final Design Thesis. If you are interested in their work, just send us an email.

The problem

Ship Shoal 32 is one of the earliest offshore platform installed in the Gulf of Mexico in September 1947. It has globally been followed by over 16,600 platform installations. Only in the Gulf of Mexico there are today more than 3,600 offshore platforms installed and operated by oil and gas companies. The decision to install a platform depends on the expected productivity and profitability of the field the platform is intended to produce from. When production falls below profitable levels the platform is shut down. The licenses agreements that oil companies have with governments require structures to be removed after production has stopped, and that environment conditions shall be restored to original conditions.

But, the costs of decommissioning are considerable (the estimated cost of the decomissioning of the roughly 500 installations on the Norwegian continental shelf could reach USD 20 billion), and some of the early international regulations (Continental Shelf in Geneva, 1958 and the United Nations Convention on the Law of the Sea in Montego Bay, 1982) have been revised shaping a more flexible and phased approach to the removal of abandoned offshore installations. Economic and cash flow considerations may influence decisions, and if economic or technical factors so dictate, operators may ask that removal be postponed. There is a great deal of uncertainty associated with the timing of decommissioning of installations. This depends on many factors, including oil prices, maintenance costs and the development of new technology for extracting oil and gas. The trend today is to extend the lifetimes of fields and installations beyond what was originally planned.

From the technical-economic perspective, the larger the structures are and the deeper they are located, the more appropriate it is to leave them totally or partially intact. Infact, the removal of steel or concrete fixed platforms is impossible without using explosive materials. This causes a very powerful, although short-term, impact on the marine environment and biota, which should not be neglected being extremely difficult to get any reliable estimates of possible mortality of marine organisms. Offshore platforms provide habitat for highly valued reef fish such as snappers and groupers. In the Gulf of Mexico for example, such habitat is scarce and offshore platforms have increased the total amount of reef habitat available by as much as 10 to 25 percent.

Design concept
An environmentally sustainable afterlife of offshore platforms to be decommissioned is an economically viable alternative to traditional decommissioning (total removal). It can be valuable to oil and gas companies, transforming a problem into an opportunity. The Redux Platforms include a series of activities complementary to each other, enabling closed loop operations. A list of these activities include:

Renewable Power Station: producing electricity and heat using: wind with low embedded energy kite based systems; waves and water streams; the sun with photovoltaics and thermal panels; organic waste to produce biogas in biodigesters. A part of the energy produced run onsite facilities, the rest is transferred to the land using the abandoned pipelines to run cables.

Green Island: a vegetable and fish production facility based on the principle drivers of future agriculture: less soil, less freshwater, no fossil energy, no pesticides and fertilisers, using only seawater and sun to produce at higher protein yields than soy, and at higher biomass yields than corn. The food island includes: integrated multitrophic aquaculture (IMTA) where molluscs are grown and their wastes are used as nutrients for seaweeds, anaerobic digestion of seaweed to produce biogas, digestate to be used as a fertiliser, electricity and heat, a seawater greenhouse cooled by evaporating seawater and irrigated by the resulting freshwater, photobioreactors growing Nitrogen-fixing marine cyanobacteria to be used as biofertilizer, using CO2 produced with biogas, tubular reactors to grow high microalge biomass to produce nutraceuticals, functional foods, and feed for fish.

Scientific Research Station: profiting of the artificial reef condition, researchers study regulation of the marine populations and coral reproduction, making underwater observations, monitoring the sea level, and collecting oceanographic and meteorological information within the framework of international projects.

University Resort: a small hosting structure with private rooms, and classrooms can accept small groups of 12/24 guests for short periods. The guests will participate at the daylife of the Redux Platform operators, and will gain an on field education on the themes of sustainability and clean energy production.

Operators Appartments: it’s the place dedicated to the lodging of the workers of the platform. It includes small appartments, a library, a kitchen and a refectory, the public spaces can be used also by the guets of the Redux University.

Base for search and rescue operations: platforms strategically located can host boat rescue crafts and helicopters.

Artificial reef: The existing structure of the rigs is often populated by a large number of marine flora and fauna species. Traditional decommissioning, based on total removal of the structure, can be a biodiversity disaster. The Redux platform will enhance mairne biodiversity, creating a much richer environment.

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