The shale oil revolution has been made possible due to the convergence of many innovative technologies such as horizontal drilling, hydraulic fracturing, and 3D seismic imaging to name a few. One of the most overlooked innovative breakthroughs making the shale oil revolution possible has been the development and evolution of the PDC (polycrystalline diamond compact) drill bit.
The PDC drill bit was first introduced into the drilling industry at Hughes Tool Company (HTC) by GE Carboloy (maker of cemented tungsten carbide) in late 1972. General Electric (GE) had earlier perfected a process for diamond synthesis under GE inventor Tracy Hall. The convergence of affordable tungsten carbide and PDC allowed for the development of the PDC drill bit.
The PDC drill bit or cutter, works by grinding its way through rock layers with PDC inserts and force from the rotation and weight of the drill string above. The rock cuttings produced from the bottom of the hole are carried up the borehole by the circulation of the drilling mud that lubricates and cools the drill bit. With shale, the PDC bit is the bit of choice. Specially designed drill bits for drilling shale are increasing ROP (Rate of Penetration) and shortening drilling times for unconventional shale gas and oil wells.
Schlumberger, an innovator in drill bit technology, has designed a shale specific drill bit specifically for unconventional shale applications. Shales often produce a poor hydraulic environment that requires high mud weights and low flow rates. Schlumberger’s Spear shale-optimized steel-body PDC drill bit is designed to deliver improved ROP while maintaining precise directional control which is crucial when drilling horizontally for up to 2 miles within the target formation. The black inserts in the diagram to the left are the PDC inserts.
A very detailed and somewhat technical paper on the historical development of PDC bits is available at: The History and Impact of Synthetic Diamond Cutters and Diamond Enhanced Inserts on the Oil and Gas Industry