Drilling in deeper formations with high-pressure/high-temperature (HP/HT) margins increases the tendency and frequency of well-control incidents related to anomalies of formation pressures and temperatures. This paper discusses how managed-pressure-drilling (MPD) technology led to cost savings in two wells drilled in the Hai Thach gas field offshore southern Vietnam. The wells were drilled from a semisubmersible tender-assisted rig with an automated MPD choke manifold and docking-station rotating control device (RCD), integrated on a flexible plug-and-play basis to enable easy rig up and rig down and the moving of equipment between wells.
Introduction
MPD systems have built a track record of success in mitigating drilling hazards related to uncertain formation pore pressures and narrow-pressure operating windows common to HP/HT exploration and development wells. In these wells, slow rates of penetration, wellbore-stability issues, ballooning, accuracy of influx-detection systems, and differential sticking can result in well-control problems and nonproductive time (NPT).
The Nam Con Son (NCS) basin off the southern coast of Vietnam presents such challenges.
