Shallow Gas Drilling Cost Optimization Through Utilization of KFDJ Diverter in Offshore Bekapai, Mahakam Field

Abstract

In the current condition of low oil prices, Oil Companies are forced to improve drilling operation efficiency and reduce drilling cost to produce hydrocarbon, moreover in mature field such as Mahakam Field operated by Pertamina Hulu Mahakam (PHM). One of main drilling challenges in Mahakam is shallow gas hazard which can lead to blowout event when drilling surface section. A new method to drill surface section with KFDJ diverter has been introduced. The KFDJ diverter system is used on jack-up rigs which replace the conventional diverter system.

Before implementing KFDJ diverter for shallow drilling, comparison between KFDJ and conventional diverter is made to perform gap analysis to PHM’s company rules and to find any modification needed on equipment or procedure to keep the operation safe and smooth. Distinctive risk assessment and mitigation are prepared to mitigate any potential additional risk when drilling shallow gas section with KFDJ diverter. A comprehensive gas dispersion study was also performed to simulate gas dispersion and heat radiation during gas evacuation process. Finally, trials are done for three wells drilling with action checklists to monitor and verify risk mitigation were fully implemented.

From the gap analysis, it was found that KFDJ diverter cannot meet the requirement of PHM’s company rules to able to do Complete Shut Off (CSO). To meet the PHM’s company rules requirement in utilizing KFDJ diverter for shallow gas drilling, kill string is utilized as mitigation of shallow gas kick possibility during non-CSO period. The gas dispersion study result shows KFDJ has another benefit due to the higher elevation which can reduce the gas exposure to shale shaker and other rig equipment during gas evacuation process. The first trial has been done successfully in offshore Bekapai with several operation modifications. It is proven that the utilization of KFDJ diverter saves up to 12.75 hours of rig time which is equivalent to cost saving of USD 133,000 per well. Shifting from conventional diverter to KFDJ diverter can also significantly reduce the amount of heavy lifting job during installation and dismantling process of diverter equipment.