Abstract

A new process for manufacture of Polycrystalline Diamond Compact (PDC) cutters creates a wrapped thermostable region across the face and around the periphery of the diamond compact.  This differs significantly from existing first-generation thermostable product as the treated region has complex geometry in three dimensions.  This paper describes the new geometry of the cutters and shows how the thermostable region supports the cutter as it slowly wears.  It also shows how the onset of wear into the tungsten carbide substrate behind the diamond layer is delayed significantly.

Laboratory test results show a 270% improvement in abrasion resistance over premium PDC material and field case studies show how the new cutter type has saved money while drilling and allowed PDC bits to drill sections that previously required multiple bit runs.

Case studies are presented from a variety of applications around the world including hard and interbedded formations and abrasive sands.  They compare direct offset runs with existing, first-generation thermostable data.

The new-generation thermostable cutter stays sharper, for longer, than either the first-generation thermostable cutter or previous non-thermostable PDC material.  It will allow development of lighter set and more aggressive bit designs able to set new standards in speed, steerability and stability without having to sacrifice durability in the design.

New cutting material developments are at the forefront of the ongoing improvement of PDC bits.  This is a significant development that shows a step change in cutter and bit performance.  It allows for the realization of a new generation, not just of cutters, but also of bit designs.

History

For many years, the manufacturers and users of PDC bits battled against the limitations of the few grades and types of polycrystalline diamond available.  Historically, there has been a classic trade-off between abrasion and impact resistance of cutters.  Typically, as illustrated in Figure 1, impact resistance was achievable by using a larger diamond grain size, but at the expense of abrasion resistance – and vice-versa¹.