When conventional recovery methods failed to retrieve a flow target left downhole, a North Sea oil and gas operator approached Oilenco to create a bespoke solution to clear the restriction and allow abandonment operations to continue.
The initial project investigation identified several potential challenges:
• Unknown orientation of the flow target
• The flow target had the ability to rotate
• The hanger type needed to be identified
• Recovery was ruled out due to tight tolerances between the seal bores and OD of the flow target.
The concept
Oilenco began a collaboration project with Welltec to create a solution that reduced the restriction caused by the flow target, maximising access to the wellbore, allowing the operator to use industry standard plugging and cutter options.
The proposal was to use a unique ‘offset or eccentric’ milling solution to drill a large hole through the flow target using Welltec milling technology.
A conventional concentric milling approach would have caused the flow target to rotate, however by creating an offset within the milling guide sleeve, the flow target would be prevented from rotating.
The result
Following successful onshore trials and approval by the client, the operation was completed. Using the Oilenco depth indicator tool, a bespoke design for the asset, the client was able to correlate the depth, determine the position of the flow target, and verify the hanger type from one run of the tool.
An offset milling sleeve was then run to stabilise the flow target and protect the seal bores throughout the operation using the results from the depth indicator tool.
Once milling was complete, a flow target conduit protection sleeve was run, allowing the operator safe access through the milled flow target for well entry and exit.
Client support
Following numerous unsuccessful fishing attempts, the client was looking for an optimised solution to solve their novel issue in the most efficient and effective way.
In collaboration with Welltec and the client P&A team, Oilenco supported the project from design, through to manufacture, providing workshop and offshore support to asset personnel helping to ensure a successful operation.
The client provided feedback stating, “The flow target was not wedged in place within the tubing hanger and could move around, so it was a great achievement in milling it and gaining access allowing a successful P&A of the well.
“Our confidence in this solution allowed us to call off the preparation of a costly coil tubing contingency. This operation is seen as a huge success.”
This article was authored by Oilenco. For more information, visit the Oilenco and Welltec websites.
