By mid-century around 5,000 wells are expected to be abandoned in the North Sea. 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).
According to bosses at Well-Safe Solutions, higher oil prices, an easing of the pandemic and careful management of the firm’s cost base have positioned it to take advantage of an upturn in decommissioning activity.
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 21-well campaign for the company, Coretrax, the global well integrity and production optimisation leader, worked closely with several service companies to perform P&A activity on six wells across two fields in the Southern North Sea. The wells ceased production in 2018.
As an example of the success of this integrated approach, P&A work on a single well, generated 32 hours of rig-time savings, significantly reducing overall risk, expenditure, and schedule.
Multi-faceted North Sea campaign
To isolate the reservoir on this particular well, Coretrax’s CX-2 bridge plug was used in the 9 5/8-inch casing at 10,500 feet. 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 company’s Drop Drift Cleaner (DDC) was then deployed to clean 1,776 feet 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 highest stands to be cleaned without disturbing the cement.
To provide a single trip Perforation and Test string, a heavy duty CX-RTP (retrievable test packer), was mobilised in conjunction with a DAV MX™ circulating bypass tool, and a non-explosive hydraulic casing punch tool (Figure 1).
The CX-RTP is a heavy-duty service packer able to withstand high pressures during squeeze cementing, inflow testing and formation fracturing while the DAV MX’s smart dart’s speed provides fast circulating options. 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 optimise the placement of the environmental cap, a CX-2 was set at 8,462 feet before 692 feet of drill pipe was cleaned with the DDC. Using the 9 5/8-inch CX-2 as a base, Coretrax then deployed a second hybrid string.
Collaborating with another service company, the CX-SVE – a squeeze packer which releases with a slick stinger – was then run with perforating guns and hydraulically set at 900 feet (Figure 2). 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.
Commenting on the ongoing SNS P&A campaign, Ben Foreman, Well-Safe Solutions’ P&A club manager, said, “Coretrax added real value to project, not only with the equipment and services provided, but also the proactive and collaborative way they contribute to our ‘one team’ approach.”
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.
As the industry continues to focus on driving operational efficiencies and responsible oil recovery, Coretrax is ideally placed to support operations at all stages of the well lifecycle with an integrated, innovative approach to well lifecycle integrity and production optimisation.
Lyndsay Harley, group sales and marketing manager, has worked at Coretrax for 8 years, holding a number of operational and marketing roles. Prior to Coretrax, she was an account manager at a major oilfield services company. Lyndsay has extensive experience support the company’s operations across the UK, Africa and Asia Pacific with a key focus on business development, operations and sales.