Innovative Completion Technologies for Highly Deviated Gas Wells in Offshore Madura Strait: Key Insights and Lessons Learned

Abstract In March 2023, Husky-CNOOC Madura Limited successfully completed 10 highly deviated offshore gas wells in the Madura Strait, Indonesia. This paper highlights several novel technologies applied, including the installation of a fiber optic permanent downhole gauge (FOPDHG), the deployment of a tractor-stroker key-tool to open the completion isolation valve (CIV), and the utilization of a casing swivel during lower completion runs. The deployment of these technologies has already taken place, representing the first of its kind in Indonesia. The process starts with a wellbore cleanout operation, followed by lower completion installation, upper completion installation, Xmas tree installation, well unloading, and concludes with well testing operations. Several new technologies were deployed at the M Fields as part of continuous improvement from previous projects. These include the installation of a fiber optic permanent downhole gauge (FOPDHG) as a permanent pressure and temperature sensor, the deployment of a tractor-stroker key-tool to open the completion isolation valve (CIV), and the utilization of a casing swivel during lower completion runs. A permanent downhole gauge was installed for reliable downhole measurements. The gauge was placed inside a gauge mandrel as part of the upper completion and installed as close as possible to the producing reservoir section. This project marked the first application of a full fiber optic system (FO PT Sensor and Fiber Optic Cable) on a dry gas well in Indonesia, including the sensor, cable, and surface data acquisition unit. As the local oil and gas industry was not yet familiar with this technology, the installation could have posed significant challenges; however, the project successfully demonstrated that such challenges could be effectively managed, proving the system could be installed and operated reliably. The completion isolation valve (CIV) was installed to allow the upper completion to be deployed in an underbalanced condition. It was mechanically opened using a tractor-stroker deployed key-tool before the well-unloading operation, optimizing operational time and cost by eliminating the need for well opening and unloading operations using coiled tubing. However, a recovery strategy was implemented during operational issues with the technologies, leading to successful completion up to the well-testing operation. The casing swivel was selected for this completion design based on experience from a previous field, where the lower completion string landed prematurely. The casing swivel was chosen as a mitigation plan to allow the running string to rotate independently. The lower completion run-in-hole process was conducted smoothly, with the premium screens landing successfully at the target depth in all wells. The novelty of this paper lies in the design and selection of innovative completion technologies for offshore highly deviated wells (inclination >60°, with this case study reaching 70°, including the fiber optic permanent downhole gauge (FOPDHG), completion isolation valve (CIV), and the utilization of a casing swivel. Additionally, it covers the operational improvements and lessons learned from their installation and application. The research presented herein is valuable and can serve as a reference for future work by other researchers and companies.