What is the difference between PDC Bit and rock bit?

1.Cutting Structure:

The cutting structure is the main point of differentiation between PDC Drill Bits and rock bits. A PDC bit has a layer of polycrystalline diamond (PCD) cutters bonded to a tungsten carbide substrate. In contrast, a rock bit, also known as a roller cone bit or tricone bit, has three rotating cones with hardened steel teeth or tungsten carbide inserts.

2. Cutting Action:

PDC bits primarily achieve cutting through a grinding and shearing action. The diamond cutters on the bit's surface grind and scrape the rock formations, breaking them into small chips or cuttings. Rock bits, on the other hand, rely on the rotation of the cones with teeth or inserts to crush, chip, and scrape the rock as they roll, creating cuttings.

3. Application:

PDC bits are generally preferred for drilling through hard and abrasive formations, such as shale, limestone, sandstone, and compacted formations. They are known for their high rate of penetration (ROP) and durability in these types of formations. Rock bits, on the other hand, are more versatile and can be used in a wider range of formations, including soft, medium, and hard formations.

4. Cost:

PDC bits tend to be more expensive than rock bits due to the cost of manufacturing the polycrystalline diamond cutters. Rock bits with steel teeth are typically more affordable, while those with tungsten carbide inserts are usually more expensive.

But,the selection of a drill bit depends on various factors, including the type of formations being drilled, drilling objectives, drilling parameters, and cost considerations. Drillers often evaluate the formation characteristics and drilling requirements to determine whether a PDC bit or a rock bit would be more suitable for the specific drilling operation.