*Applications of Polycrystalline Diamond (PCD) Materials in Oil and Gas Industry DOI: http://dx.doi.org/10.5772/intechopen.107355*

distribution in the diamond structure. Traditionally, PDC cutters can be manufactured at relatively low pressures and temperatures, around 5.5 GPa and 1400°C, respectively, due to metal catalysts. However, these metal binders reduce the hardness of polycrystalline diamond (PCD) materials to approximately 50−70 Gpa [7]. More seriously, when the formation or rock drilling operation generates high frictional heat, the metal catalyst binder in the PCD layer will unfavorably help the diamond turn back into graphite. In addition, the cutting and drilling process exposes the PCD material to high stresses, where PDC cutting edges with cobalt binders tend to produce microcracks and diamond particles fall/collapse when the stress is greater than the binding strength of the diamond grains in the PDC cutters at a specific temperature. The reason for this can be explained by differences in the modulus of elasticity and coefficient of thermal expansion between the cobalt metal binder and the diamond, which can lead to a mismatch between the volume change of the diamond and the binder in a high-stress and high-temperature operating environment. As a result, large stresses are created inside the PDC material, leading to early failure. Therefore, the whole drill bit industry tried to leach out the metallic binder from the diamond structure to improve the thermal stability. But this can reduce the fracture toughness of the PDC cutting structures and shorten the drill bit life. Developing a catalyst-free or binderless PDC cutter for drill bits would be an ideal and game-changing technical solution that has the potential to achieve the goal of "one run to total depth" in drilling technology.

This chapter will highlight their own research and development of binderless or catalyst-free micro polycrystalline diamond (MPD) PDC tools and related drill bit technologies in the oil and gas industry. Ultra-high pressure and ultra-high temperature (UHPHT) technologies make this possibility a reality. UHPHT technology is cutting-edge technology developed for many advanced superhard materials. Currently, the technology is mainly focused on the study of nanocrystalline diamond (NPD). However, their industrial applications are limited by small sizes and/or high costs. In Japan, researchers [8] developed a Kawai type 2–6-8 large-cavity hydrostatic pressure device that successfully achieved a high pressure of about 15 GPa when synthesizing millimeter-scale nanocrystalline PDC materials. Since then, after nearly 10 years of further development, the size of synthetic NPD has been successfully increased to the centimeter level. Larger tonnage high-pressure units are required to obtain larger sample sizes and ensure reasonable high-pressure efficiency. In anvil design, high reliability and efficiency are mainly affected by load losses during the transmission process, of which the structural design of the anvil assembly and the strength of the anvil material in the final stage are the most important. The progress of our UHPHT technologies will be introduced.
