For the development drilling phase of Ca Ngu Vang (Golden Tuna, Block 9-2, offshore Viet Nam), the 17 ½-in. section was deepened, compared with previous wells, to better suit the well design. The technological challenge centered on drilling the interbedded sand and shale Con Son sequence through the Bach Ho Shale, to total depth (TD) the section in the early Miocene with one drill bit and bottomhole assembly (BHA) at an economically viable rate of penetration (ROP).
Operator Hoan Vu JOC previously tested several different drilling methods with limited success, including employing a roller cone drill bit on rotary and later a PDC bit in tandem with a mud motor. This paper discusses the post-offset well analysis and the cooperative effort between the operator and service company that resulted in the introduction and successful implementation of a new 16-in. PDC bit and rotary steerable system (RSS) with real-time vibration monitoring. The new BHA combination drilled the section in one run, surpassing all ROP expectations, while meeting all directional drilling objectives. Following the successful run, which was the first application of a 16-in. PDC bit and RSS tandem in Vietnam, the bit exhibited minimal wear.
The authors examine the application and share the technical and operational lessons learned with recommendations for optimizing performance in future similar applications.