Publications

Drilling through hard massive carbonate formation combined with naturally induced torsional vibration due to bit-formation interaction is often resulting in unnecessary down time caused by downhole tool failures, sub-optimal drilling performance and extra trip to change out worn out bit. The torsional vibration is also well known as as stick and slip. To address the challenge, special PDC bit with advanced cutter technology were utilized in ERD well in Offshore East Java. The key focus when selecting the bit was on PDC cutter shape selection to improve drilling efficiency and utilization of higher strength material elements to improve stability and impact durability of the cutting structure critical in drilling hard and harsh rocks. The bit record, bit type configuration, QA/QC process, hydraulic & stability analysis and secondary cutter materials consideration were also specifically analysed when selecting this bit to improve bit performance further and ensure the bit could be repairable & reusable after being used. The first field run of the bit incorporating all this technology mentioned above was performed on last two (2) ERD well drilled in East Java Offshore area, at the 8.5in hole section with 7 bladed, 16mm cutter. The bit successfully drilled total of 3,029 ft interval through massive carbonate formation for both wells. The bit reached target depth without bit change. The bit had proven to reduce drilling torsional vibration stick & slip from severe to medium level. Both bit run also had set considerably remarkable slip-to-slip Rate of Penetration (ROP) for ERD wells category, which had significantly improved by 69.35% compared to previous ERD well drilled in same carbonate formation with ERD profile. When on surface, the bit was observed still in excellent condition for this application. The enhanced PDC bit selection had proven to enable drilling into more challenging torsional vibration induced formation in massive Carbonate formation and challenging ERD trajectory thus improving overall drilling performance and achieve actual rig time & cost saving compared to plan.