A new technique to monitor the long-term integrity of suspended or decommissioned oil and gas wells in the North Sea is in development via a collaborative project including Heriot-Watt University, Sentinel Subsea and the Oil & Gas Innovation Centre (OGIC).
The North Sea is currently home to approximately 11,000 oil and gas wells with 2,379 expected 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. In both cases, industry lacks a standard approach at this stage in a well's lifecycle to integrity monitoring and environmental liability.
The new project will address this challenge by building 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 and, on breaching the sea surface, 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 even small leaks. The development is already showing promising results in the laboratory.
Professor David Bucknall from the School of Engineering and Physical Sciences at Heriot-Watt University explains the challenges:
“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.
“It also needs to remain 'dormant' for an extended period of time, sealed within the well. 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 nearing completion 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 later in 2019.
Neil Gordon, Chief Executive Officer at Sentinel Subsea, said: “Environmental assurance and cost reduction are the two cornerstones of well decommissioning. It is vital that the North oil and gas industry can ably demonstrate proactive, best practice of environmental stewardship to all stakeholders throughout the late life and decommissioning process, whilst working towards the Oil and Gas Authority's reduction target of 35% on current cost projections.
“Sentinel Subsea's technology provides that environmental assurance whilst providing the confidence for industry to adopt innovative decommissioning techniques that could make a huge contribution to that cost-saving objective. Furthermore, the early-detection offered by our technology also has the potential to significantly lower clear-up costs.
“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 Oil & Gas Innovation Centre said: “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 £15.3 billion 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.
“With the total decommissioning expenditure over the next 10 years expected to reach £15.3 billion 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.”
“The industry as a whole is striving to reduce decommissioning expenditure by 35% by 2035 and this non-invasive, environmentally-friendly monitoring system has the potential to monitor thousands of decommissioned and suspended wells across the UK and further afield at low cost.
“With the objective of driving innovation in the sector, OGIC continues to actively engage with those companies that see the benefit of investing in these important niche market technologies. A continued investment and collaboration in these projects is not only vital for the future of the sector, but also vitally important to maintain Scotland's lead in innovative technologies for the oil and gas sector - both in the UK and globally.”
- Source: Oil & Gas UK Decommissioning Insight Report: Facts and figures November 2018