What Does Polycrystalline Diamond Compact Bit Mean?
A polycrystalline diamond compact (PDC) bit is a bit that uses synthetic diamond disks, called "cutters," to shear its way through rock with an ongoing scraping motion. The PDC bit is particularly suited to drilling through shale formations, which present some specific problems with regard to borehole instability, such as borehole narrowing.
At least one major offshore drilling organization advocates for the use of an oil-based drilling fluid and a PDC bit to help alleviate or at least mitigate this issue.
Trenchlesspedia Explains Polycrystalline Diamond Compact Bit
PDC bits come in two styles: a matrix body and a steel body bit. Matrix bits are used at times and in environments where steel body PDC bits suffer body erosion. Steel bodies, on the other hand, can withstand impact loading better than matrix bodies.
The diamond cutters are synthetic diamond material, but not a single synthetic diamond. Rather, clusters of diamond grit (about 0.00004 inches in size) are aggregated into larger masses of crystals with a random orientation. These aggregated crystals are shaped into the cutting surfaces, called diamond tables. Because they bond easily and well with tungsten carbide materials (which can themselves be brazed to bit bodies) they overcome the problem of attachment by brazing to the bit, which synthetic diamonds, unaided, cannot do.