This paper describes the application of using new 3D shape PDC cutters in XX development wells in offshore Sarawak. Based on historical drilling data from offset wells around the XX Field, multiple bit trips were required on each section from 17-1/2" until 8-1/2" holes. Various bit manufacturers had come up with several bit designs to drill this field. Post-run bit dull reports showing that those bits were worn out due to formation related issues which were suspected due to interbedded soft shale and abrasive sandstone.
One of the greatest challenges that any PDC bit manufacturer encounter today is the combination of crushing (roller cone) and shearing mechanism (PDC) into drilling challenging formation with single drilling trip. Current PDC application into hard rock drilling, where impact damage, heat damage and abrasive wear of PDC cutters limit its performance. XX Field formation profile with interbedded soft shale and abrasive sand make it impossible to predict on ideal bit selection with combining PDC and Roller Cone runs together effectively.
The challenges have led to the development of a new 3D shape PDC cutter tested in XX Field development wells successfully. The client saved multiple trips of PDC bit runs and drilled 50% farther, double rate of penetration (ROP) than the best PDC bit run in the offset wells. The revolutionary bit cutter design works well regardless of any hole size and BHA configuration. This study will present an analysis of the drilling data from the field and provide a detailed description of the bits and cutter design achievement by comparing the performance of both roller-cone and conventional PDC.
The 3D PDC cutter design has generated a stable rotation and reduced vibrations throughout drilling which resulted in improved ROP while extending the bit life at the same time. The new ground-breaking bit cutter design has provided a viable solution to drilling interbedded soft shale, abrasive sandstone with unexpected hard stringers.