Across the globe, a growing number of oil and gas platforms and facilities are coming to the end of their lives as they are no longer productive. Decommissioning is part of the normal life cycle of every oil and gas installation - when an installation reaches the end of its life, and the economically recoverable oil and gas reserves have been extracted from the reservoir, the installations need to be ‘retired’ and then decommissioned by being dismantled, recycled, and disposed of.
In this blog post, Aubin’s Adam Brown discusses the decommissioning process, and the common issues faced within the industry.
Starting his career as a chemist, Adam has worked in product development, HSE, and project management before moving into business development at Aubin. With an in-depth knowledge of the industry, and experience managing projects from start to finish, Adam tells us first hand why these challenges occur, and potential solutions for overcoming them.
Challenges within the industry
“One of the biggest problems faced in decommissioning is that depending on the asset, the approach may vary. Assets can vary from large multi-well platforms to small platforms, FPSOs, and subsea wells, therefore it is unlikely that a company will find a ‘one size fits all’ solution.
“One well could be relatively easy to abandon, whilst another might need a lot of remedial work done before any plugs can be set.
“Over the space of my career I’ve worked on many projects and only one thing stays the same - that there really isn’t a ‘one size fits all’ solution. It’s important to evaluate each and every project individually and develop a plan that addresses its own individual challenges. Here are some of the most common challenges faced…”
1. Aging infrastructure
“With aging infrastructure, there’s a high probability that some lines will be corroded or pitted which will create restrictions on the maximum operating pressures, resulting in products running at a very low differential pressure to adhere to safety restrictions.
“As many assets have been around for over thirty years, it’s likely that they have deteriorated from their original state in one way or another. Often original documentation can be difficult to trace, creating knowledge gaps that subsequently lead to delays during execution.”
2. Limited access to pipelines
“Pipelines coming to the end of their life need to be cleaned, removing any hydrocarbon before they are decommissioned.
“However it’s not uncommon for there to be limited or restricted access to a pipeline, which can be problematic. Often there is one way into the line through something like a segment that’s down a platform leg, which can only be accessed by two men going down via rope access - a costly, potentially hazardous and time-consuming process.
“When faced with limited access, we have recommended using one of our gel products such as a separator gel to clean the line. The liquid or cross-linked gels are a pumpable solution that can be applied from the deck, pumped down hosing, and effectively clean the pipeline by efficient displacement.
“As well as keeping the operation time down, this approach is also more environmentally sound as the gel acts as a barrier ahead of a seawater flush to ensure all hydrocarbon is removed from the pipeline without using any more water than is required.”
3. Maximising recovery from pipelines
“It is recommended that all materials are removed completely from a line before it is sealed off permanently. As a result, lines will often be given a thorough clean before grouting or cutting begins.
“A common issue faced when cleaning a pipeline is that you cannot be reliant on flushing water through, as it doesn’t always work. Because the oil is lighter than water, it can sit in offtake lines or, depending on profile, in highpoints within the pipeline.
“Our water-based gel solution, TORT, is an effective solution. It is lighter than oil, and will displace in any cavities and attic sections above the main flow, successfully recovering the oil and leaving the line clean. Deployed as a pig train, TORT is a lightweight gel that sits between two EVO-Pigs. Because the gel is immiscible with oil, there is a high level of separation making it easier to treat after recovery, minimising the amount of slop or oily waste produced.”
4. Non-piggable pipelines
“Pigging is used to clean the line of hydrocarbons and debris before decommissioning. Mechanical and foam pigs are often the go-to options for pigging, however, depending on the pipeline, this may not be viable.
“Traditional pigging methods often cannot be used for complex pipelines that have varying diameters, short radius or 90 degree bends, as well as flow lines or flexible flow risers.
“Using shape memory technology, our EVO-Pigs can deform to half their original diameter to travel through long stretches of pipeline of varying diameters, allowing our customers to clean the line without any issues. When returning from reduced diameters, this chemical memory property means the EVO-Pig will return to its original sizing and ensure an efficient seal is maintained.
“In addition, the physical properties of these EVO-Pigs allow them to navigate bends and pipe types which could potentially have been considered formerly unpiggable.”
5. Safe removal of pipelines
“The main priority for our customers is the safe removal of their pipelines, ensuring that the lines are cleaned or sealed, and no hydrocarbon leaks into the environment.
“Our sealing agent, AXI-Lokk, is a silicone elastomer that, once cured, provides an inert plug, preventing any potential seepage of hydrocarbon out of lines once cut.
“When deployed, AXI-Lokk is in a liquid form with a tailorable density. Being hydrophobic, if pumped lighter than seawater from above, it will form a distinct layer above the seawater in the line and disperse the water, filling every cavity and groove. Within 24 hours, the product will cure and create a tight, solid plug within the line, allowing for safe removal.
“Although these are the most common challenges faced, the processes and technology used in decommissioning is ever-evolving. We are regularly approached by customers who are facing a new problem, and we work together to create innovative solutions, using our tried and tested technologies in new and novel ways.”