Because the shearing action of PDC cutters are more efficient than the crushing action of a button or tooth bit, fixed cutters are in high demand.
In 1982, PDC drill bits accounted for only 2% of total footage drilled. In 2010, 65% of total footage drilled was by PDCs.
The diamond drill bit is used in nearly all applications including geothermal energy drilling, mining, water well and natural gas drilling and oil well drilling. Total depths range from 100' to 20,000'.
PDC drill bits are used extensively in the natural gas drilling.
Impact damage, heat damage and abrasive wear all inhibit a drill bit's performance and can occur in even the softest geological formations. However, the most difficult formation for a PDC bit to drill are extremely abrasive ones.
With PDC popularity on the rise, bit manufacturing companies are seeking new materials and design aspects to make a tougher bit without compromising ROP.
Drill Bit With Damaged Cutters
HOW PDC CUTTERS ARE MADE
Cutters are made using a combination of high heat and high pressure. Man made diamonds can be grown in 5-10 minutes. Because of this diamond content, a fixed cutter bit may also be known as a diamond drill bit.
Cutters are made from a carbide substrate and diamond grit. High heat of around 2800 degrees and high pressure of approximately 1,000,000 psi forms the compact. A cobalt alloy is also present and acts as a catalyst to the sintering process. The cobalt helps bond the carbide and diamond.
During the cooling process, the tungsten carbide shrinks at a rate of 2.5 times faster than the diamond. Controlling this stress, as with most aspects of drill bit design, is called Intellectual Property, and manufacturers rarely, if ever, share their secrets.
LARGE VS. SMALL CUTTERS
As a general rule, large cutters (19mm to 25mm) are more aggressive than small cutters. However, they may increase torque fluctuations. Additionally, if the BHA has not been designed to handle the increased aggressiveness, instability may result.
Smaller cutters (8mm, 10mm, 13mm and 16mm) have been shown to drill at higher ROP than large cutters in certain applications. One such application is limestone.
Also, bits designed with smaller cutters but more of them can withstand higher impact loading.
Additionally, small cutters produce smaller cuttings while large cutters produce larger cuttings. Large cuttings may cause problems with hole cleaning if the drilling fluid cannot carry the cuttings up the annulus.
COMMON DIAMOND DRILL BIT PDC CUTTER SIZES
Mining/Geothermal/Shallow Oil and Gas
|0804||8.20 mm||4.50 mm||0808||8.20 mm||8.00 mm|
|1004||10.00 mm||4.50 mm|
|1304||13.30 mm||4.50 mm|
|1303||13.30 mm||3.53 mm|
|1308||13.44 mm||8.00 mm|
Oilfield Drilling Bits
|1308||13.44 mm||8.00 mm||1313||13.44 mm||13.20 mm|
|1608||.16.00 mm||8.00 mm|
|1613||16.00 mm||13.20 mm|
|1908||19.05 mm||8.00 mm|
|1913||19.05 mm||13.20 mm||1916||19.05 mm||16.00 mm|
API Standards: API standards, including pin sizes for drill bits and acceptable tolerances for rock bits and pdc bits.
Atlas Copco: Atlas Copco bit selection guide, examples of shirttail protection, and TCI and steel tooth cutting structure.
Button Bits: Button bits offer several advantages over PDC drill bits: they are less expensive and can withstand higher impact.
Drag Bits: Drag Bits manufactured as one solid piece of alloy steel offer greater durability and reliability. Available in step and chevron styles for hard rock drilling.
Dull Grading: Dull grading drill bits is important but often overlooked. This process provides valuable information for proper bit selection.
IADC: The IADC classification system for tooth and button bits explained as well as dull grading codes and what they mean.
IADC Classification: The IADC classification system for PDC bits: pictures and explanation of what it means and how to use it.
PDC Cutters: Because of PDC cutters, PDC bits drill sixty-five percent of total footage. Their shearing action is more efficient than the crushing action of tricones.
PDC Drill Bits: Available in either matrix or steel bodies, PDC drill bits offer higher rate of penetration than tricones in many different formations.
Tricones: With the exception of cutting structure, tricone bits are designed in the same manner regardless of manufacturer.
Well Completion Bits: Well completion drill bits from Atlas Copco in both tooth and button bits. Bear Claw, Hurricane, Aardvark, and PDC diamond mill bits from KC Bit & Supply.