PDC drill bits have grown from niche to mainstream products by gradual, subtle evolutions in design and materials technology. Occasionally, there have been more dramatic step changes in design or materials that have launched PDC bits into new applications. This paper will talk about such a step change: the design, manufacture and application of a contiguous blade of polycrystalline diamond. Rather than blades made up from individual cutters, as with a conventional PDC bit design, this bit has full-length, contiguous polycrystalline diamond coverage, without gaps between cutters on each blade. The advantages of this arrangement are many. Most obvious is the ability to drill erosive and/or abrasive formations without erosion. Often PDC bits, especially lighter set bits, can lose steel or matrix body material between the cutters due to erosion or abrasion, and this can be life-limiting. With no gaps between the cutters, this ceases to be a problem. Other possibilities include: bits for more conventional formations where a contiguous blade can be used instead of backup cutters, enhancing ROP and stability. The paper describes how various challenges were overcome: bit design; materials selection; polycrystalline diamond blade manufacture. It will also discuss applications of this technology in bits specially designed for the oil sands in northern Alberta, Canada, focusing on:
Dull condition enhancement as a result of avoiding cross-blade erosion and abrasion
Polycrystalline diamond blade durability
The effect of a smaller number of contiguous blades on ROP and PDC bit economics.
This represents a step change in bit design with the potential to redefine bit design across the applications spectrum.