Drag bits can be either solid or welded construction. Solid, or one piece construction, is the most durable and recommended for all oilfield and natural gas applications where error cannot be tolerated.
Only one bit manufacturer makes a one piece carbide drill bit - Kay Rock Bit Company!
Because of the large flow course, the Kay bit is suitable either for air or fluid drilling and does not detract from the bit's strength.
All tungsten carbide tips are silver soldered to the bit wing by a special process to ensure a strong bond that will not shear or break when drilling through hard rock.
All Kay bits are one piece construction of alloy steel forged or cast with tungsten carbide cutting tips and gauge sides to insure long life.
Drag bits come in two designs: step and chevron. Step drill bits are designed to drill soft to medium formations while chevron type bits are for harder formations.
STEP DRILL BIT
A step drill bit is used for drilling overburdens with sands, clays and soft formations. These bits will produce larger cuttings than a Chevron style bit.
Because the step drill bit is more aggressive than the Chevron, ROP will be higher. However, it will be less durable as well.
Rotary table speed should be between 60 and 80 rpm with light weight on bit (WOB).
CHEVRON DRILL BIT
Chevron drill bits are used for drilling more abrasive formations like soft sandstones and shales.
The Chevron style bit is more durable than the step drill bit but, because of cutting structure, will penetrate more slowly.
Rotary table speed should be between 50 and 60 rpm with light to medium weight on bit (WOB). Harder formations require more WOB.
3 WING OR 4 WING?
Simply put, 4 wing bits are the most durable AND have the lowest ROP.
When making a decision on which bit to buy, however, don't purchase a 3 wing just to be able to drill faster. Always remember that damaged carbide cutters slow penetration rates.
Additionally, 4 wing bits are more stable and tend toward drilling a straighter hole.
Kelly bits are commonly used for table drive rigs. Common threads are 2 3/8 IF, Mayhew regular, Failing or Mayhew Junior. The extremely long gauges help condition the hole.
DRAG BIT SIZES - 3 7/8" to 26"
AVAILABLE THREADS - 2 3/8", 2 7/8", 3 1/2", 4 1/2", 6 5/8" API Regular Pin
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.