The composite sheet of the PDC drill bit is usually cylindrical, and a thin layer of synthetic diamond is made on the tungsten carbide substrate. When drilling, the shape of the composite sheet must be kept intact to ensure that the drill bit can operate reliably in accordance with the designed 3D geometry cutting structure.
The cutting structure of a PDC bit may seem simple, but it is usually the most complicated part of a PDC bit design. Usually, the composite pieces are arranged in rows for better cleaning of cuttings. Each row is arranged along the top of the blade, protruding downward, supporting the cutting structure and keeping it in place, while effectively connecting the cutting structure to the end of the drill string. Between the blades is a chip flute, which is a channel through which the drilling fluid washes the cuttings from the face of the drill bit during drilling.
The bit body of PDC bit is divided into carcass and rigid body. The interface of the carcass PDC bit is made of steel and transitions to tungsten carbide composite material on the outer surface. The steel body PDC drill bit is made of crude steel and then coated with hard surface material to increase corrosion resistance.
The PDC bit can be designed into almost infinite variable combinations, so it can be modified according to the drilling application. The demand side can design and adjust it by engineers and designers by proposing performance requirements.
The ultimate goal of designing a PDC bit mainly includes two, to increase the total footage or the ROP.
Before the design starts, we need to fully understand the drilling application, including drilling rig capacity, speed (RPM), weight on bit (WOB), flow rate (TFA), drilling tool (BHA), formation strength and hardness, and drilling distance. After collecting and analyzing this information, the previous similar execution methods and execution results should be compared and analyzed according to the drill bit database. Before proceeding to the bit design part, these empirical data and all external factors should be used to create design and performance expectations.