An extreme extended-reach drilling (ERD) well in the South China Sea was drilled with a complex BHA incorporating multiple drilling and LWD technologies. Despite multiple challenges, the well was successfully drilled to a new regional ERD record of 9,508 m-MD with zero stuck pipe events and successful casing installation.

China National Offshore Oil Corporation (CNOOC) wanted to develop the Enping 21-4 oil field in the South China Sea with two extreme extended-reach wells drilled from an existing production platform. Located at an average water depth of 89 m and with well depths exceeding 9,500 m, the field aims to reach a peak production of 5,300 BOE/d oil equivalent by 2025.

The project faced several challenges, including the difficulty of drilling with extreme extended reach and due to the increased risk of stuck pipe. Historical data indicate that the rate of stuck pipe is close to 30% in ERD operations offshore China for wells exceeding 8,000 m-MD. The formation's abrasive sands and hard stringers are detrimental to the reliability of downhole tools. Additionally, the wells had to cross three faults, and a narrow mud weight window made effective ECD management difficult.

The drilling operation set the record for the region's deepest production well at 9,508 m. The project had zero stuck pipe incidents, and all casing strings were successfully installed.

To achieve these results, the operation used it's complex hexa-combo BHA for ERD wells for the first time in China. The innovative BHA included multiple drilling and LWD technologies.

The PowerDrive Xcel™ rotary steerable system featured an enhanced design with thermally stable polycrystalline sleeves for better resistance to abrasive sands and a high-flow kit for improved hole cleaning. Additionally, the OptiDrill™ real-time drilling intelligence service helped monitor downhole conditions and avoid stuck pipe risks.

Advanced LWD services used in the operation included the NeoScope™ sourceless logging-while-drilling service, GeoSphere HD™ high-definition reservoir mapping-while-drilling service, and PeriScope Edge™ multilayer mapping-while-drilling service to deliver efficient reservoir mapping and accurate data collection. The TruLink™ definitive dynamic survey-while-drilling service eliminated stationary survey time, reducing stuck pipe risks.

Success was also driven by meticulous prejob planning, close collaboration with CNOOC, and effective teamwork with other service providers. Continuous monitoring of drilling dynamics, BHA motions, and key variables helped identify and manage risks, ensuring smooth operations. This field development approach has set the example for similar CNOOC projects.