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Abstract High-Pressure High-Temperature (HPHT) wells are typically associated with high complexity, technically challenging, long duration, high risk and high Non-Productive Time (NPT) as many things could go wrong especially when any of the critical nitty-gritty details are overlooked. In this particular project, the complexity and risk are amplified due to possible losses in carbonate reservoir, high level of CO2 and H2S contaminants with elevated bottom hole pressure requiring high mud weight in excess of 17 ppg. A challenging contingency Pressurized Mud Cap Drilling (PMCD) program needs to be deeply scrutinized to handle high water-based "Light Annular Mud" (LAM) density of above 16 ppg during monsoon season in an offshore environment. In addition to that, due to the requirement for proper casing shoe placement to cater for a deep and high pressure well, long interval of under-reaming across interbedded formation with hard stringers is another challenge that needs to be overcome. The above sums up the challenges an operator had to manage in a final HPHT carbonate appraisal well in Central Luconia area, off the coast of Sarawak before the forthcoming development campaign. The result is imperative to fine-tune the engineering design to achieve the most optimized operation in the multiple well drilling campaign where significant cost saving is expected. With the completion of this well, it continued to push the historical envelope of such well category where it sets a record as the deepest and hottest carbonate HPHT well with high level of contaminants to be drilled in the region, and possibly globally. This last appraisal well (Well X) took more than 4 months to drill of more than 4000m of interval, covering 5-hole sections followed by well test which was carried out in a safe and efficient manner. With the seamless support from host authority, Joint Venture partners and all contractors, the well was successfully delivered. This paper will share the experience of the entire cycle from pre-job engineering/planning, execution and gathers key lesson learnt for future exploitations in similar environments.
Ong et al. (Tue,) studied this question.