As this relatively new technology matures, the cost of PDC drill bits is decreasing while the quality is greatly improving.
In the right formation and application, PDC drill bits can drill twice as fast or more than roller cone bits. You can save a lot of time and money. But should you replace your roller cone drill bits with PDC bits? This article will give you a general idea to start considering.
What is the difference?
The most immediate difference is that there are no moving parts in a PDC drill bit. They are constructed as follows:
Tricone drill bit consists of three “cones” that all have to spin on lubricated bearings. This lubrication in turn requires a grease reservoir, and for any medium or large project, some kind of bearing seal is needed to prevent debris from entering the cone body and stopping the rotation.PDC fixed cutter drill bits are solid and contain no moving parts.
PDC drill bits are made by combining fine-grained synthetic diamond and tungsten carbide under extremely high heat and pressure.
PDC & Cone Cutting types are also different.
PDC is used to split the rock, while Tricone is used for grouping and crushing.
A tricone drill bit requires relatively high drilling pressure to perform well. Otherwise, its blades may wear out prematurely.
Advantages &Disadvantages
PDC drill bit：Fast, safe, long service life，Cutter fracture in high impact formations
The ruggedness and strength of PDC drill bits give them many advantages over tri-cone drill bits.
Most importantly, PDC bits have a longer lifespan, which means they don’t need to be replaced as often as tricone bits. This reason alone explains much of the migration to PDC bits on large projects.
In addition, under optimal conditions, PDC bits can achieve higher penetration rates than roller cone bits. These factors combined mean that in formations where you have identified the rock type and selected the correct PDC bit, you can drill faster and farther with a single PDC bit, reducing the cost per foot to less than the cost of the roller cone body.
Although rotary cone drill bits may be cheaper upfront, on the right project that can take full advantage of the capabilities of a PDC drill bit, using a PDC drill bit will ultimately save money in the long run.
Finally, because roller cone bits consist of several different moving parts, there is a risk of losing part of the cone in the hole, a risk that does not exist with PDC bits.
Tricone drill bits: Wide range of applicable formations, low initial investment, more control options, better suited to hard rock formations, more impact resistant, slower drilling efficiency, shorter lifespan, possibility of ‘’cone” loss.
One of the biggest advantages of tricone drill bits is the length of time they have been in use. This length of time has allowed for significant advances in the design and manufacture of tricone drill bits, incorporating advances in material technology such as tungsten carbide inserts, or advances in engineering technology such as sealed journal bearings.
Roller bits are also easier to control in tricky situations, offering more options regarding torque and weight.
The action of a single roller on a tri-cone drill bit is used to break up the rock, making it more flexible in the range of formations in which one drill bit can be used.
One of the most important considerations for any drilling project is always cost, and all things being equal the cone body will tend to come out ahead. However, depending on the specifics of the drilling project, there may be a case for a PDC bit to come out ahead.
Conclusion
PDC bit is ideal for certain formation conditions. It is suitable for consolidated homogeneous rocks such as shale, sandstone, limestone, sand, clay.
When you mention your rock, you can try PDC bit as a fast, safe, reliable (low cost in the long run) solution.
Otherwise, roller cone bit is your best choice.
