Successful Casing Drilling Experience with Premium Connection for Production Casing Application on a Subsea Well

Abstract

Abstract This paper discusses the casing design and connection selection process where the first Casing while Drilling (CwD) technology was deployed in a subsea exploration well in the Dampier Sub-Basin, Northwest Shelf offshore Australia to overcome the problematic drilling operations while drilling through the highly porous "Bare Sands" which often led to severe loss circulation. This was the first attempt for the operator to deploy a newly developed Threaded and Coupled (T&C) Type Premium Connection on 9-5/8-in. 47 ppf L80 for production casing application with CwD technology. Hence, the process of identifying and mitigating risks when applying new connection technology in a highly critical application was vetted thoroughly. It is understood that not all premium connections are suited for such application to meet key selection criteria, such as fatigue performance, torque resistance and being able to maintain gas sealability whilst under severe well load conditions including tension and compression loads after being subjected to severe cyclical bending stress during CwD operation. In order to ensure that the connection survives the continuous abuse during CwD in order to meet the objective of the well, a newly developed T&C connection from VAM® was selected for this challenging application. The connection is characterized by easy field make up, exceptionally high torque resistance, excellent gas sealability which is in compliant with ISO 13679 CAL IV and it comes with superior fatigue resistance attributed to the new and innovative connection technology. The casing drilling operation was completed from a semi-submersible rig reaching a world record depth at 1,906 m in technical limit time with drilled interval of 1,710 m. The successful deployment of 9-5/8-in. 47ppf L80 with this newly developed premium connection for production casing opens up a new chapter for similar CwD applications in the industry.