An early warning system that detects leaks in oil and gas wells – dubbed a ‘smoke alarm for the sea’ – is being developed by scientists and industry specialists.
Developed by Sentinel Subsea, Heriot-Watt University in Edinburgh and the Oil & Gas Innovation Centre, the new environmentally friendly technique will focus on the long-term integrity of suspended or decommissioned wells in the North Sea.
The North Sea is currently home to around 11,000 oil and gas wells, with almost 2,400 due to be decommissioned over the next 10 years.
Suspended wells must be inspected; however, this is neither continuous nor frequent, and there is currently no obligation to inspect abandoned wells, according to the team.
In both cases, it is claimed the industry lacks a standardised approach at this stage in a well’s lifecycle to ensure its integrity, monitoring and environmental reliability.
The new project will address this challenge and builds upon a concept conceived by Sentinel Subsea to develop an environmentally benign tracer compound, known as SWIFT, that will be pumped into a well before it is sealed.
If the well leaks, the compound will react solely with a detector material, known as the trigger, at the seabed.
The highly selective and specific tracer-trigger reaction will then cause a buoyant beacon to detach. When the beacon reaches the sea surface, it will communicate via satellite with its base station, alerting the need for further investigation of the specific well to which that beacon was assigned.
Designed to act like a “smoke alarm for the sea”, the system will be capable of detecting smaller leaks, and the developers say it is already showing “promising results” in the laboratory.
Professor David Bucknall, of Heriot-Watt University, said: “The SWIFT compound we are developing cannot be found naturally in the environment as this could cause a false positive detection but must, at the same time, be completely non-toxic and non-hazardous to allow it to enter the sea environment from the well.”
“We also need to ensure that it does not react with any of the materials and compounds that exist in the wells already,” Bucknall added. “It also needs to remain ‘dormant’ for an extended period of time, sealed within the well.”
Speaking about the team’s progress, Bucknall said: “We are testing materials that can last for up to 100 years by artificially ageing the compound under lab conditions.
“The position of the trigger on the seabed means it can be more readily replaced so this will need to last for approximately 10 years.”
The project will focus on three critical stages. The chemical design is currently under way and will be followed by laboratory and simulated field trials before independent external validation tests.
The materials will then be commercially produced in sufficient quantities to begin offshore trials conducted by Subsea Sentinel in wells in the North Sea before Heriot-Watt scientists evaluate the trial data and ensure functionality matches lab-based results.
Widespread production of the system is expected to begin later this year.
Neil Gordon, CEO of Sentinel Subsea, said: “Our partnership with Heriot-Watt University, supported by the Oil & Gas Innovation Centre, allows our technology to begin its tangible journey to make global decommissioning a safe, highly efficient industry.”
Ian Philips, chief executive of the Oil & Gas Innovation Centre, added: “During 2017, for the first time, the number of wells being decommissioned was higher than the number of new wells being drilled.
“With the total decommissioning expenditure over the next 10 years expected to reach £15.3bn on the UK continental shelf alone, collaborations like this between Heriot-Watt University and Sentinel Subsea have the potential to bring further cost efficiencies and increase environmental safety standards to the sector.”