Dissolvable Technology Enhances Operational Efficiency of Offshore Completion Operations on the NCS

Abstract

Abstract In a typical well completion system, retrievable plugs run on wireline are used to set production packers and thereafter, to perform leak testing of the upper completion tubing. There are significant costs and risks associated with these intervention operations to set and retrieve aforementioned plugs. This paper presents the development and implementation of a system using dissolvable technology that allows for interventionless packer-setting and tubing testing of upper completions. The solution developed is a packer-setting kit consisting of a seat profile and a dissolvable ball. The seat is run as part of the tubing string below the production packer. After landing the completion string, the dissolvable ball is dropped from surface to land on the seat profile below the packer. This ball-seat system holds pressure from above, thereby, enabling the production packer to be set and a leak testing of the tubing to be performed. Eventually, the ball dissolves completely in the presence of downhole packer fluids permitting start-up of production activities. This paper documents the extensive qualification test program which was undertaken to qualify a dissolvable ball-seat system for one-such application. These tests were aimed to verify the capability of the packer-setting kit to fulfil the operational requirements (pressure rating, dissolution time periods) under the specific downhole conditions (packer fluid type, temperature). Following successful qualification testing, this solution was successfully implemented in 3 wells on the Norwegian Continental Shelf in 2018. Adopting this technology significantly improved operational efficiency by reducing well completion and intervention times along with associated costs. Consequently, this enabled earlier production start-up on these wells. The most challenging aspect of this new approach is the selection and qualification of a suitable dissolvable ball material appropriate for the application-specific requirements and operational constraints. The various steps and tests necessary to verify suitability of dissolvable technology for such applications are outlined in this work. Key operational considerations which need to be kept in mind when implementing this solution shall also be addressed.