Types of Drill bits Used in Drilling Rigs

Drilling rigs employ a diverse range of drill bits, each tailored to specific drilling tasks and geological conditions. One of the most common types is the roller cone bit. As mentioned earlier, the threecone roller bit is widely used. These bits are designed with cones that have teeth, either steelmilled teeth or tungsten carbide inserts. Steeltooth bits have cones with wedgeshaped teeth milled directly into the cone steel. To enhance their durability, extremely hard tungsten carbide material is often welded onto the tooth surfaces. Tungsten carbide insert (TCI) bits, on the other hand, have shaped teeth made of sintered tungsten carbide pressfit into drilled holes in the cones. Some steeltooth bits may also incorporate TCI elements in addition to the milled teeth. The cones rotate on roller or journal bearings, which are usually sealed to protect them from the harsh downhole drilling fluid environment. A pressurecompensated grease lubrication system is also commonly used to ensure smooth operation of the bearings.
Another important type is the PDC bit. PDC bits are fixed cutter bits that use polycrystalline diamond compacts as the cutting elements. These diamond compacts are extremely hard and wearresistant, making PDC bits highly efficient in drilling through soft to mediumhard formations. The design of PDC bits allows for highspeed rotation, which can significantly increase the drilling rate. The diamondtipped blades on PDC bits scrape and shear the rock as the bit rotates, effectively removing material and creating the hole.
There are also diamondimpregnated bits. These bits are often used in drilling hard and abrasive formations. The entire bit body is impregnated with small diamond particles. As the bit wears during the drilling process, new diamond particles are continuously exposed, providing a constant cutting edge. This makes diamondimpregnated bits very suitable for longterm and deep drilling operations where the formation is particularly tough.