Publications

Tunu is a mature giant gas field in Mahakam which is already entering a production declining phase. Most of the wells are targeting marginal reserves using a combination of grid systems and seismic target reservoirs. This causes an increase of trajectory complexity. Simple J-shapes were a standard profile prior to industrialization drilling campaigns introduced in the 2000; where well trajectories were shifted to S-shape profiles, which present more challenges including stick-slip while drilling and difficulty during tripping out the BHA. These issues have lead to increased well durations and subsequently higher well costs. These well costs have needed to be reduced in order to allow for continuous and economical drilling operations. PDC drill bits with self-adjusting depth of cut control technology yielded positive results in overcoming the challenges of drilling on S-shape trajectory profile in the Tunu Field. Severe stick-slip which had normally occurred in the dropping section at deeper depths was drastically reduced. Less restriction was also observed while tripping out the BHA which indicated a smoother and less tortuous wellbore. On-bottom ROP on this bit trial was the highest among the field for the wells which have similar profiles and well TD depth. Overall, this initiative significantly reduced the well duration by almost 3 days, a 20% reduction from the initial planned well duration. The success of this adjustable depth of cut control technology has shown to significantly improve performance and lower well costs, aiding in the economical continuation of drilling operations in Mahakam.