SDX was an exploration well drilled on a jack-up rig, which was located offshore on the west side of the Malay basin. The well was classified as an ultra high pressure high temperature (HPHT) due to 455°F (235°C) maximum formation temperature and 11,200 psi maximum formation pressure. SDX was a very important well for a major operator in the attempt to explore and evaluate the potential hydrocarbon prospects in the field.
SDX field was well known for its drilling challenges due to extreme narrow window and HPHT condition. The pore pressure ramp steeply increased at shallower depth causing narrow drilling operating window between pore pressure and fracture gradient. Thus, the well was considered as conventionally “un-drillable” and managed pressure drilling (MPD) was a necessary enabler to achieve the well objectives.
MPD was deployed to drill the last four hole sections, 12 ¼” × 14 ¾”, 8 ½” × 12 ¼”, 8 ½” × 9 ½” and 5 ¾” × 6 5/8” to mitigate the challenging wellbore issues. The drilling strategy was to use a lower mud weight (MW) in order to walk the pore pressure line and allow the use of optimum drilling flow rates. Two essential MPD procedures were implemented to safely verify drilling window. The pore pressure ramp was established by performing static flow check (SFC) and the losses limit was established by conducting dynamic formation integrity test (DFIT). Furthermore, total depth (TD) criteria for the MPD section was defined by the minimum window required to perform managed pressure cementing (MPC) for the liners.
SDX well was successfully drilled to TD after overcoming defying wellbore challenges due to narrow window, pore pressure ramp uncertainty and HPHT condition. MPD was fully utilized to drill four most critical sections. MPC was performed splendidly for 11 ¾” and 9 7/8” liners without influx or loss. The paper will further explain on how proven MPD solutions were planned and executed to drill this exploration HPHT well. MPD and MPC lessons learned were also highlighted in this paper as part of the knowledge sharing.