PDC or tricone in HDD? May the best bit win!
PDC (polycrystalline diamond compact) bits and tricones have advanced over the years. The market is constantly changing and adapting - to new and improved materials and designs.
PDC’s and tricone’s have pros and cons for the HDD environment.
Advantages of a PDC:
PDC bits don’t require significant weight on bit to support the cutting action. A PDC bit will drill fast and shear the rock, rather than grinding and crushing. Whether this is more effective than a tricone will depend on the ground, your equipment, and experience using the tooling.
PDCs:
Are fast cutting in the right formation
Have no moving parts
Shear rock through scraping action
Have a long life
Have higher rates of penetration
PDCs may cost more than tricones, but they last longer when used in their optimal conditions.
Advantages of a tricone:
Tricones have been around a long time, and have been the traditional go to bit - when needing to deal with harder conditions requiring an AT style rig or mud motor. Tricones work by grinding and crushing, with its three roller cones.
Tricones:
Are a familiar tool that drillers understand how to use to best effect
Work well in inconsistent ground conditions
Have a lower cost
Are hard hitting
Are very versatile
Have more control with torque and weight
If you are able to source a tricone built specially for HDD, it will have extra gauge protection, which helps reduce wear on the shirtail on the bottom of the hole.
Ground conditions in Australia:
PDC
Consolidated ground
Sandstones
Clay
Soft sands
Tricones
hard rock
unconsolidated ground
abrasive ground
Ground conditions in New Zealand:
PDC
East Coast Bays formation
Consolidated hard formation
Tricones
Basalt
Gravel and unconsolidated formations
Hard rock with fissures
There are advantages and disadvantages to both tricones and PDCs; with geology, drilling fluids and rig capacity all coming into consideration. With a combination of a good drilling fluid system, lubricated bits, and a smooth operator at the helm - winner winner chicken dinner!
For help in determining the right bit for your HDD project, please talk to one of our Sales Managers. Blick stocks a leading range of tricones and PDCs, and partners with M-I SWACO for drilling fluids.