Executing PMCD with Downhole Isolation Valve (DIV) with Annulus Access in Shallow Water Wells

Abstract

Offshore carbonate drilling in Malaysia involves drilling through karst features that often lead to severe loss circulation, impacting approximately one third of the wells drilled. These losses typically occur near the carbonate top, rendering conventional circulation ineffective and increasing well control exposure during tripping, particularly in high-angle development wells. The Downhole Isolation Valve (DIV) provides a reliable downhole isolation mechanism that enables safe and predictable operations under losses conditions while improving completion efficiency. The DIV is a flapper-type downhole isolation valve installed within the 9-5/8″ tieback casing, providing full-bore access and operated via dual encapsulated control lines connected to a surface control unit. After Pressurized Mud Cap Drilling (PMCD), the DIV and tieback casing may be retrieved in line with the selected completion strategy. Design enhancements, including integration with ported joint or autonomous inflow control devices functioning as check valves, have further improved operational flexibility and flow assurance. Field applications across multiple campaigns in Malaysia have demonstrated that DIV deployment with annulus access significantly reduces well control exposure, minimizes reliance on conventional loss mitigation methods, and mitigates secondary risks such as stuck pipe, poor wellbore clean up, and productivity impairment. The DIV has proven to be a reliable enabler for high-risk, high-angle carbonate developments, delivering safer operations and more predictable campaign outcomes. This paper presents the evolution of DIV application in Shell Malaysia, key learnings, and future development opportunities for candidate wells where the technology can deliver the greatest value.