Confidently setting an environmental barrier for plugging and abandonment (P&A) operations has traditionally been limited to complex and costly mechanical bridge plugs and inflatable devices.
With a patent pending, eight CX-Enviroplugs have so far been run across Norwegian and UK P&A projects in the North Sea. The most recent was completed in the Southern North Sea for a major, independent European operator. It is particularly suited to wells requiring an environmental barrier to prevent the leakage of oil-based mud.
Originally designed to act as a simple base for cement, the tool has been enhanced to allow the option of pressure testing in larger ID casing. Available in a range of sizes up to 20”, the three-finned tool, which allows accurate self-centralization, now incorporates a compression set element. The design is also able to pass through a smaller wellhead restriction.
The plug is typically run on the drill pipe. Once at depth, a ball is dropped, and pressure applied to shear out the disconnect sub. This leaves the lower section of the disconnect sub and the plug downhole. Once released, an open-ended disconnect sub is left and cementing can take place simultaneously. The disconnect tool utilised on the CX-Enviroplug is also suitable for other applications.