Unity delivers North Sea preparatory P&A pressure testing

Unity, Europe’s largest provider of well integrity technology, services and engineering solutions, has successfully completed a preparatory P&A project in partnership with oilfield services provider Petrofac.

The Aberdeen-based business deployed its Temporary Abandonment Cap Test Tool (TACTT) to pressure test two suspended mudline wells in the North Sea in support of an end of life campaign undertaken by Petrofac for a multinational operator.

The TACTT is the only technology of its kind, able to seal on to any type and size of temporary abandonment (TA) cap fitted to a suspended well, pressure test the seal to ensure well containment, then test and vent pressure from below the TA cap. It can also leave a reliable secondary seal in place if required.

The technology is designed to provide a fast and mobile method of pressure testing, to simplify and improve safety for the re-entry of suspended wells. It also allows operators to understand the amount of pressure accumulation below the TA cap since the last intervention so the information can be factored into the operational plan for decommissioning.

In this project, the technology quickly confirmed zero pressure below the TA caps of the two wells, allowing efficient plugging and abandonment (P&A) operations to continue.

The TACTT was deployed on drill pipe from a rig, however it can also be cable deployed for vessel-based P&A activity and added cost efficiency. Only two engineers are required for deployment and it can be rapidly mobilised to meet operator schedules. In this case, the TACTT was delivered within just one week, returned to Unity after the first well, redressed in 3 days and then remobilised for the second well.

Gary Smart, Unity CEO said: “Re-entering offshore wells, which may have been suspended for a considerable number of years, is challenging and high risk, particularly as any pressure build up behind the back-pressure valve of the TA caps cannot usually be measured. For the first time, there is a safe and efficient method to test and vent these wells prior to re-entry.

“This latest project in partnership with Petrofac, builds on our successful track record and the value the industry already recognises in the TACTT technology. We look forward to continuing to deliver further cost, efficiency and safety benefits for our clients through this and our other innovative technology.”

With well abandonment activity in the UKCS increasing four-fold since 2016¹ the TACTT technology was developed to solve a related operational challenge, improve safety, reduce cost and meet increasing operator demand.