Installation of Long Interval Conductor String Across Challenging Offshore Drilling Environment

Conductor string installation has always proven to be key element process for a successful well construction in offshore project. However, challenging drilling environment such as rough current presents a huge resistance for the conductor string installation with conventional drilling technique. Previous offshore exploration activities have seen many case studies with failure on conductor installation causing significant delay on drilling operation consequently impacted with higher project cost. Non-retrievable casing drilling technology, has gained wide reception from operators in Asia Pacific region for drilling top hole sections in offshore project recent years. The high value realized in reduction on well construction costs and efficient installation process across challenging drilling environment has contributed to the high popularity of this innovative drilling technique in the region’s offshore work. A non-retrievable casing drilling bit has been successful in previous casing drilling application across Myanmar shallow water. The previous success has raised interest for an attempt in pushing deeper conductor string setting depth to simplify well design and determining the ultimate capability of this system in drilling a 549 m conductor string, the deepest 20-Inch string set with casing drilling technique in Asia Pacific region. A new Leopard SD casing connector with higher torque capacity was first time utilized on a casing drilling application in this project. This paper introduces the planning and implementation process of the long interval 20” casing drilling through challenging drilling environment in this project. In the paper it also discusses the detail running procedure, drilling parameters involved, operational results of the casing drilling bit, casing connector’s performance and lesson learnt from the project.