Chipping Resistant Polycrystalline Diamond and Carbide Composite Materials for Roller Cone Bits

Abstract

Cemented tungsten carbide and polycrystalline diamond are the most critical materials used for roller cone bit cutting structure. Chipping and catastrophic breakage are the primary failure modes for the materials and hence the limiting factor of service life of a drill bit. Chipping and fracture resistance can be improved at the expense of hardness and wear resistance of the materials. This trade-off between wear resistance and chipping resistance hinders the development of super hard materials for demanding drilling applications. Functionally designed composite materials of polycrystalline diamond (PCD) and cemented tungsten carbide (WC-CO) that offer enhanced chipping resistance without significantly sacrificing wear resistance are studied and reported in this presentation. Specifically, one example of the functionally designed composite materials is a honeycomb structured composite of polycrystalline diamond (PCD) and WC-Co and its application for diamond enhanced inserts for roller cone bits. The PCD/WC-Co composite takes advantages of high modulus and superior wear resistance of diamond, while it mitigates chipping and cracking using the tougher WC-Co as cell boundaries. The overall engineering properties and performance are superior to that of pure PCD. Another example of functionally engineered hard materials is double cemented (DC) tungsten carbide. Double cemented tungsten carbide has 50% or higher fracture toughness than conventional cemented tungsten carbide at equivalent wear resistance. When compared to tool steels, DC carbide has equivalent fracture toughness but much higher wear resistance. Field tests of honeycomb structured diamond enhanced inserts (CDEI) demonstrated the controlled chipping characteristics and longer durability of components as compared to conventional homogeneous PCD materials with comparable wear resistance. DC carbide also exhibited excellent damage tolerance during field tests in demanding applications where excessive heat checking and fracturing of inserts are common failure modes. Introduction Polycrystalline diamond and other hard materials are widely used in oil and gas drilling as well as other earth boring applications. Diamond enhanced inserts (DEI) for roller cone bits as an example has steadily gained acceptance in more and more applications. Chipping and catastrophic breakage are the primary failure modes for the materials and hence the limiting factor of service life of a drill bit. Figure 1 shows typical failure modes observed of diamond enhanced inserts. Chipping and fracture resistance can be improved at the expense of hardness and wear resistance of the materials. This trade-off between wear resistance and chipping resistance hinders the development of super hard materials for demanding drilling applications. It is an obvious desire, but a difficult challenge for engineers and scientists to seek means to improve fracture toughness without having to compromise wear resistance. The present paper discusses a new approach, characterized as "functionally designed microstructure", which attempts to improve functional mechanical properties as well as some intrinsic properties by means of a composite microstructure. For the purpose of discussion, mechanical properties of materials can be classified into two categories: intrinsic and functional properties. The hardness and fracture toughness are intrinsic properties. Wear and chipping resistance are the functional properties. Functional properties are determined fundamentally by the intrinsic properties; but are affected by service conditions, i.e., external mechanical and chemical environment.

Evaluation of the Wear Resistance and Electrochemical Behavior of Drill Bits for Drilling Oil and Gas Wells

“…Together, different types of drill bits, in the process of working, are not only subject to wear processes, but are also in contact with chemically aggressive environments, meaning that corrosion can play a pivotal role in the degradation of the surface and can significantly accelerate wear [3]. Furthermore, despite their extensive use and excellent abrasion resistance, PDC tools are still very susceptible to fractures [4][5][6][7][8][9]; this is why the development of the wearing surface of PDC and TCI bits is one of the most crucial problems in drilling industries, considering that excessive costs can result from the improper choice (or design) of the cutting tool [10]. This is mainly a result of their relatively low fracture toughness [1] and because the bit wear is considered an intrinsic cost, although significant savings are achievable through the effective control and minimization of the bit wear [11].…”

“…This is mainly a result of their relatively low fracture toughness [1] and because the bit wear is considered an intrinsic cost, although significant savings are achievable through the effective control and minimization of the bit wear [11]. Finally, although there are various wear studies on PDC drill bits and on TCI uncertainties, there is no information on their corrosion behavior [4][5][6][7][8][9]11]. For this reason, the objective of this research is to determine the relation between microhardness and abrasion wear on two bodies through the pin-on-disc test.…”

Evaluation of the Wear Resistance and Electrochemical Behaviour of Drill Bits for Drilling Oil and Gas Wells

“…Together types of drill bits at the time of working the components are not only subject to wear processes, but are also in contact with chemically aggressive environments, corrosion can play an important role in the degradation of the surface and can significantly accelerate wear [3]. Furthermore, despite their extensive use and excellent abrasion resistance, PDC tools are still very susceptible to fractures [4][5][6][7][8][9]. This is why the development of the wearing surface of PDC and TCI bits is one of the most crucial problems in the drilling industries due 2 to the excessive costs that can result due to an improper choice (or design) of the cutting tool [10].…”

“…Therefore Development of the wear surface of the PDC bits is one of the most crucial problems in the drilling industries on account of the excessive costs which may result due to an inappropriate choice (or design) of the cutting tool [10]. Finally, although there are various wear studies for the PDC drill bits and for the TCI uncertainties, there is no information on their corrosion behavior [4][5][6][7][8][9]11]. For this reason, the objective of this research is determining the relation between microhardness and abrasion wear on two bodies through the pin or disc test.…”

Failure analysis and optimum structure design of PDC cutter

“…The PDC cutter is widely prevailed in the markets of measuring and cutting tools, down-hole tools of oil and gas drilling, mining and geothermal drilling industries. It owns key performance indicators including but not limited to wear resistance, high hardness, good thermal stability and impact toughness [2].…”