By mid-century around 5,000 wells are expected to be abandoned in the North Sea.1 To achieve the OGA’s target of reducing decommissioning costs by 35%, operators must cut the overall outlay of well plugging and abandonment (P&A).
Challenge
With this anticipated level of activity, technical innovation and collaboration are key to improve efficiency, reduce rig-time, and lessen the financial burden of this essential end-of-life procedure.
As part of a continuing multi-well campaign with Well-Safe Solutions, Coretrax worked closely with several service companies to safely perform P&A activity for the first six wells of a 21-well campaign across two fields in Southern North Sea. The wells ceased production in 2018.
In a single well, this integrated approach generated 32 hours of rig-time savings, significantly reducing overall risk, expenditure, and schedule.
Multi-faceted solution
To isolate the reservoir, Coretrax’s CX-2 bridge plug was used in the 9 5/8” casing at 10,500ft. Unlike other mechanical barriers, it features a release system which provides a slick stinger with a through-bore to enable optimal subsequent cementing operations, eliminating the need for a dedicated second trip for cementing operations. The Drop Drift Cleaner (DDC) then cleaned 1,776ft of pipe allowing the uppermost stands to be cleaned in situ, removing the need to re-run the pipe for cleaning. Together these operations saved more than 16 hours of rig-time.
The DDC package consists of a drop drift brush, containing a weighted bullnose and handle with a bristled cleaning element, as well as a land out sub which is pre-installed in the drill string before running in hole. After cementing operations, the brush is dropped from surface and free-falls through the drill string before landing out in the bespoke internal profile of the catcher sub. The drill pipe is then pulled out of hole and the catcher sub is broken out before deploying a foam wiper ball to clean the remaining stands of drill pipe. Using the DDC allows the uppermost stands to be cleaned without disturbing the cement.
To provide a single trip Perforation and Test string, the heavy duty CX-RTP (retrievable test packer), the DAV MX circulating bypass tool, and the non-explosive hydraulic casing punch tool were combined. This modular, hybrid approach allowed the well to be displaced to 10.1ppg brine to give an overbalance, to punch the casing, and successfully complete the critical inflow test in a single run.
To further optimize the placement of the environmental cap, a CX-2 was set at 8,462ft before 692ft of drill pipe was cleaned with the DDC. Using the 9 5/8” CX-2 as a base, Coretrax then deployed a second hybrid string.
Collaborating with another service company, the CX-SV – a squeeze packer which releases with a slick stinger - was then run with perforating guns and hydraulically set at 900ft. Subsequently, perforations were made and cement was squeezed in behind and up the perforations to ensure the annular cement plug was in place. With no mechanical setting tool necessary, cement was placed on the disconnected CX-SV to create a one-trip solution, saving further rig time on this well abandonment operation.
Achievements
Coretrax aligned its P&A product line technologies and that of other suppliers to generate rig-time savings of 32 hours for the abandonment of this single well.
This collaborative, multi-technology approach clearly demonstrates that varying technical interfaces can work together for reliable, efficient, and cost-effective P&A projects in the future. It has also shown that even more significant savings can be made at greater depths.
Testimonial
“During this ongoing SNS P&A campaign, Coretrax has added real value to the project, not only with the equipment and services provided, but also the proactive and collaborative way they contribute to our #oneteam approach.”
Ben Foreman
P&A Club Manager
Well-Safe Solutions
