Novel Lightweight Thixotropic Cementing Brings Operational Efficiency to Major Operator in Malaysia Ultra-Deepwater Operation

Abstract Cementing ultra-deepwater exploration wells involves complex operational and technical challenges, particularly where water depths closed to 10,000 feet. In Malaysia, these are further compounded by narrow pore pressure and fracture gradient (PPFG) margins, low seabed temperatures, and shallow flow hazard. This paper details the successful deployment of a novel lightweight, thixotropic cement system, proposed as a practical alternative to foam cementing, which remains uncommon in the region due to logistical and cost constraints. The system features rapid gel strength development and aggressive thixotropic behaviour, effectively mitigating gas migration during the critical gel strength period (CGSP) – the time between the development of critical static gel strength (CSGS) and 500 lbf/100 ft2. The paper outlines the system’s full development cycle, including blend and fluid design, field execution, and post-job evaluation. During the operation, over 700 barrels (bbl) of customized slurry were pumped for a riser-less 20-inch casing section, achieving full returns at the seabed. Post-placement remotely operated vehicle (ROV) surveillance confirmed sheath integrity, with no visible gas bubbling. This successful case not only met technical and operational objectives but also demonstrated reduced complexity and enhanced reliability compared to traditional foam cementing methods. It sets a benchmark for scalable, lightweight thixotropic cementing strategies in Asia-Pacific deepwater developments.