New Ultra-Strong and Catalyst-Free PDC Cutting Element Technology

Drilling very hard, abrasive and interbedded formations requires PDC cutters not only to possess higher wear resistance and higher impact resistance but also sufficient thermal stability. PDC cutters from conventional high pressure and high temperature (HPHT) technology have limited thermal stability due to the presence of unavoidable Cobalt (Co) catalyst in the cutting structure. Here, we report a new game-changing PDC cutter technology via ultra high pressure and high temperature (UHPHT) technology to produce the world-first ultra-strong and catalyst-free PDC cutting elements. Conventional HPHT technology usually has a synthesis capability of pressures of 5.5 GPa to 7 GPa. In our study, the UHPHT technology is achieved by an innovative two-stage multi-anvil apparatus with novel high pressure assembly designs for generating ultra high-pressures up to 35 GPa - seven times higher than current PDC cutter technology. Micro-sized man-made diamond powders are used as a starting material without the use of any catalyst to make ultra-strong and catalyst-free PDC cutting materials using this high pressure work hardening approach. The design principles and experimental study of centimeter-sized sample chamber for novel 6-8 type two-stage static ultra high pressure apparatus will be detailed. The conventional PDC cutter manufacturing HPHT technologies will also be reviewed. The hardness and fracture toughness of the new cutting materials were evaluated using a Vickers hardness tester. The new ultra-strong PDC cutting materials without using any catalyst were synthesized under applied pressures - nearly three times higher than current PDC cutter manufacturing pressure. The Vickers hardness of the ultra-high pressure synthesized PDC cutting materials reached the top limit of the single crystal diamond, more than 200% higher than current PDC cutters. The PDC cutting elements also possess the metallic fracture toughness that is also more than 200% higher than that of current PDC cutters. More importantly, the PDC cutting materials exhibit the industry record on wear resistance, more than 200% higher than current PDC cutters. Materials characterization including SEM and TEM indicated that the breakthrough performance is directly related to the unique micro-/nano composite microstructure developed under ultra high pressure work hardening conditions. The ultra-strong and catalyst-free PDC cutting elements achieved by innovative ultra high pressure and ultra high temperature technology represent a breakthrough for oil and gas drilling technology.