Drilling Cost Optimization by Improvement of Reentry Well Operational Efficiency in Mahakam Field Offshore Asset Development

Abstract

The oil price downturn has driven Oil Companies to improve drilling operational efficiency in maintaining low cost for drilling to produce hydrocarbon, moreover in mature field such as the Offshore Asset in Mahakam Field operated by Pertamina Hulu Mahakam (PHM). Re-entry well drilling campaign by sidetracking from existing well has become one of the main strategies initiated by PHM for Offshore Mahakam development to reduce capital cost for a new well. Several optimizations are introduced in order to improve operational efficiency and reduce well cost.

The project is initiated by mapping conventional method of a re-entry well operation, starting from plug & abandoned (P&A), re-entry drilling preparation, milling casing window, drilling sidetrack hole, open-hole logging data acquisition, and well completion. The possibility of improvement on each step are reviewed, covering engineering and operational aspect, including alignment with PHM’s company rules, and impact on cost reduction. Special procedures and risk assessments are formulized to ensure all the initiatives can be executed smoothly without issue. Proper selection of parent well candidate is also defined to improve  operational efficiency. Field implementation trials are scheduled to allow adequate time to gain operational feedback for next improvement plan.

Many trials have been done in Offshore Mahakam drilling campaign by applying all of improvements. Those are rigless P&A, whipstock setting and milling optimization, and e-line logging through casing window. All of these improvements can be successfully executed without any major issue, particularly on HSEQ. Reduction of well duration is up to 10 days between the conventional method of a re-entry well campaign at the 1st well drilled in June 2019 until the latest well with operational
optimization drilled in May 2020. This optimization is equal to around 2 Million USD saving on well cost which is significant in the current environment where most of the wells have marginal reserve. As per today, there are 12 re-entry wells that have been delivered and still counting. Room for improvement is still foreseen to furthermore squeeze the well duration and boost the economics of the wells.