Gas Tight Mechanical Casing Anulus Packer Enables Compliance with Well Design and Barrier Requirements for Re-Entry Multilateral Application in 20+ Year Old Well on Norwegian Continental Shelf

With continually increasing drilling costs, the importance of utilizing existing slots in offshore platforms has never been higher in increasing average rate of recovery from the Norwegian Continental Shelf. Utilizing existing slots for new targets that were once inaccessible due to a multitude of reasons including technology limitations, value justification, among others pose many challenges for the operator. One of these challenges specifically relates to compliance with current well design criteria and barrier requirements. As our industry has evolved, more stringent design criteria and additional well barrier requirements ensuring well integrity have become commonplace. In addition, integrity reduction of previously installed downhole components must be accounted for. Utilizing casing strings and polished bore receptacles (PBR's) that have been installed and exposed to harsh downhole environments for 20 + years create a need for innovative solutions Through this paper we will demonstrate how through proper planning and equipment selection the operator was able to successfully install a gas tight mechanical casing annulus packer in a tieback string. This provided mechanical isolation of the previous casing string that had been exposed to years of wear. Traditional solutions of a tieback seal stem stung into a PBR were not possible due to expected condition of the seal surface in the PBR from years of down hole exposure. The rigorous qualification and validation program of the packer led to its selection in this application. Acceptance criteria of ISO 14310: V0 was used as the basis for testing. This included testing in a casing joint that had been previously installed in a well for 25+ years, mimicking downhole environments for this application. The annulus packer was installed integral to the tieback casing and activation was combined with subsequent installation of multi-lateral junction equipment. Requiring no dedicated runs for installation or activation provided additional value for the operator. The packer was tested as per well design criteria which allowed the operator to proceed with well construction and continue to new target with upmost confidence in barrier compliance and well integrity.