PROFOR

This project research deals with the development of cutters for ground and underground excavation with a ''composition gradient'' with the lowest ratio of cost per foot in the underground and deep oil well drilling operations where excessive cutters consumption and low rate of penetration are an issue. The exploration of oil in deeper and deeper geological formations and geothermal operations require to design drill bits that should be capable to drill rocks at high temperature (350°C), heterogeneous, extremely hard and abrasive. For this type of drilling environment, the most suited bit is still the PDC bit (Polycrystalline Diamond Compact) composed with a hardmetal WC-Co substrate covered with a diamond table; this type of drill bit is aggressive in ductile and slightly abrasive formations. However, PDC cutters have a low impact resistance while drilling strongly heterogeneous formations, which reduces and limits their field of application to more homogeneous formations. Tricone bits offer a better wear resistance but suffer from impact weakness. This project has as an ambition to develop new cutters for both PDC bits and tricone bits that overcome the well established compromise between the hardness and the toughness of WC-Co. The development of these cutters will extend both abrasive and impact resistances of the bits through the improvement of the wear resistant part on the frictional area PDC cutter's substrate and an impact resistant part in the centre of the cutter. That is obtained thanks to the development of a new process of 'Controlled Liquid Phase Migration in a hardmetal WC-Co by liquid Co binder", which allows to locally adapt the properties of the cermet by modification of its binder content. The result of this research will be therefore perfectly transferable on WC-Co inserts used in drilling, civil engineering and construction which will be more reliable due to the continuous cobalt gradient that makes their surface harder and their centre more ductile. The consortium is composed with a drill bit manufacturer (Varel Europe) and its cutter supplier (Diamond Innovations sub-contractor of varel Europe) and three academic research laboratories can cover all the investigation fields involved the project: from the elaboration to the application. The complementary of the field of interest and of the competencies of the partners makes the consortium more reactive and more suitable to bring innovative solutions