A recent report by the Oil and Gas Authority estimated that 45% of all decommissioning expenditure in the UKCS is through P&A of wells. The current cost estimate of decommissioning is £51 billion with the government and industry aiming for an ambitious 35% reduction by 2022.
Unity has developed the Temporary Abandonment Cap Test Tool (TACTT) in response to this significant industry demand. It seeks to safely and sustainably drive down costs and increase efficiencies for P&A operations.
The TACTT can seal onto any type and size of TA cap, pressure test the seal to ensure well containment, then test and vent pressure from below the cap by stabbing the back pressure valve (BPV) and is able to leave a reliable secondary seal in place if required.
Crucially, the technology can be deployed either from a rig or alternatively from a vessel through open water.
Vessels have greater availability than rigs, can be deployed faster and generally save between 30-50% in costs when compared to rig-based intervention. Further economic, safety and environmental benefits can be realised when the TACTT can be deployed across multiple wells in region-wide vessel campaigns to pressure test, survey and prepare them for abandonment.
Testing for pressure accumulation below the TA cap provides operators with an accurate understanding of the well’s condition, allowing informed decisions to be made for the next stage of decommissioning. This may be to continue with vessel-based intervention or alternatively to leave the TACTT safety valve in place and return with a rig at a later date.
The technology is already field proven and has returned substantial savings for a number of clients.
“Unity’s TACTT allowed Spirit Energy to successfully abandon two North Sea wells in line with UK Government regulations. The tool removed all risk associated with re-entering a suspended well and the ability to deploy by vessel provided significant project savings.”
Olav Log, Director of Drilling and Wells at Spirit Energy
Spirit Energy approached Unity to overcome risks when re-connecting to temporary abandoned wells prior to decommissioning. This innovative tool addresses the potential pressure behind the TA cap safely.