Abstract
An operator in the North Sea planned an 11-well field development which included installation of long 4-½ in. completion liners in the horizontal reservoir sections of each well. Successful completion liner deployment was identified as a major project risk based on liner deployment challenges experienced in earlier development campaigns in the field. The new drilling campaign had plans to include the longest length laterals drilled and completed in the field to date. Additional challenges included complicated geology, widely varying pore pressure profiles over the length of the laterals, and open hole stability/enlargement concerns. An incomplete understanding of the mechanisms at play in prior drilling campaigns further increased risks of not being able to achieve the planned total depth with the completion liner.
To minimize overall risk, the operator planned to use a managed pressure drilling (MPD) technique to maintain conditions as ‘near balanced’ as possible during both the reservoir drilling and completion phases of the operation. It was hypothesized that MPD would enable the successful drilling of challenging pore pressure profiles and minimize openhole stability issues. This would, in turn, improve the likelihood of successful completion liner deployment. Despite the expected positive impact of MPD techniques, a strong understanding of the downhole dynamics during deployment of the lower completion liner was needed.
To address this challenge, the operator installed a newly developed workstring dynamics logging tool directly above the liner hanger running tools. This tool continuously recorded axial loads, torque, temperature, and pressure data during the lower completion liner deployment operations. The data provided by the tool helped facilitate continuous operational and design improvements by establishing best practices and troubleshooting unexpected results/issues. The data also helped the team understand root causes and develop appropriate mitigations, significantly reducing downtime. These improvements allowed the operator to overcome known challenges from previous campaigns to achieve a robust deployment strategy and add significant project value.
