PDC Bits are the workhorses of the oil field. Features such as cutter types, cutter layout, and blade geometry are continuously being evaluated and improved to deliver value and drive down drilling costs. Certification with the IDEAS integrated dynamic design and analysis platform ensures these bits offer optimal performance.
Additionally, the IDEAS platform and field experience show that a single dynamically stable bit design can provide exceptional performance with a variety of drilling systems, especially in directional drilling. The earlier perception was that each type of rotary steerable system (RSS) or steerable motor BHA required its own bit design with highly specialized directional features. Bits with IDEAS platform certification are stable and produce less torque and stick/slip in transitional drilling. The risk of time-consuming and costly trips due to shock and vibration is greatly reduced.
Matrix-body
“Matrix” is a very hard, rather brittle composite material comprising tungsten carbide grains metallurgically bonded with a softer, tougher, metallic binder. Matrix is desirable as a bit material, because its hardness is resistant to abrasion and erosion. It is capable of withstanding relatively high compressive loads, but, compared with steel, has low resistance to impact loading.
Steel-body
Steel is metallurgically opposite of matrix. It is capable of withstanding high impact loads, but is relatively soft and, without protective features, would quickly fail by abrasion and erosion. Quality steels are essentially homogeneous with structural limits that rarely surprise their users.
Design of matrix and steel-body bits
Design characteristics and manufacturing processes for the two bit types are, in respect to body construction, different, because of the nature of the materials from which they are made. The lower impact toughness of matrix limits some matrix-bit features, such as blade height. Conversely, steel is ductile, tough, and capable of withstanding greater impact loads. This makes it possible for steel-body PDC bits to be relatively larger than matrix bits and to incorporate greater height into features such as blades.
Advantage of matrix-body PDC bits
Matrix-body PDC bits are commonly preferred over steel-body bits for environments in which body erosion is likely to cause a bit to fail. For diamond-impregnated bits, only matrix-body construction can be used.
Development of PDC bits
Fortunately, both steels and matrix are rapidly evolving, and their limitations are diminishing. As hard-facing materials improve, steel bits are becoming extremely well protected with materials that are highly resistant to abrasion and erosion. At the same time, the structural and wear-resisting properties of matrix materials are also rapidly improving, and the range of economic applications suitable for both types is growing.