Unique PDC bit technologies combine to reduce drilling time in interbeddedformations

Interbedded formations cause difficulty when selecting a drill bit for opti mum section performance. Hard stringers require bit features that conflict with those required far softer homogeneous formations. Limited by conventio nal technology, this culminates in the selection of a bit tao heavy set to maximize penetration rates through the soft formation or too light set to d rill the hard stringers. This paper describes a unique combination of PDC b it technologies that provide a solution to consistently drill interbedded f ormations without compromising bit selection. The unconventional design con sists of features to maintain high-penetration rates in soft formations and the stability and life required to pierce through hard stringers. The technologies are combined on a steel bit body. The nature of this mater ial allows its fundamental engineering properties to be exploited to produc e extreme features that cannot be achieved using matrix powder technology. This material is the cornerstone that expands the design and manufacture wi ndows for conventional PDC bit technologies. Soft formations imply high-penetration rates: the technologies developed ar e a novel hydraulic arrangement, bit face design, cutter size, and usable d iamond volume. Hard stringers require high stability in order to maintain b it life by preventing premature component failure. Technologies developed a re conventional antiwhirl theory, localized cutter placement to extend bit life, and an innovative low-friction gauge pod that spans two blades and en closes a junkslot. The case history demonstrates the significant performance improvement that can be achieved through interbedded formations by combining innovative PDC bit technologies. The study examines the development of the 12 1/4-in secti on in the Tunu field, Indonesia. The continual development of the project i s discussed including a lighter set variant to complete the same applicatio n and the successful translation of the design philosophy into a slim-hole program.