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==Factors to consider during bit selection and operation==
== Factors to consider during bit selection and operation ==


Some important rules to help guide in drilling bit selection are discussed below:
Some important rules to help guide in drilling bit selection are discussed below:


===Rules of thumb for bit selection===
=== Rules of thumb for bit selection ===
* Shale has a better drilling response to drill speed. 
* Limestone has a better drilling response to bit weight. 
* Bits with roller bearings can be run at a higher speed than bits with journal bearings. 
* Bits with sealed bearings have a longer life than bits with open bearings. 
* Bits with journal bearings can be run at higher weights than bits with roller bearings. 
* Diamond product bits can run at higher speeds than three-cone bits. 
* Bits with high offset may wear more on gauge. 
* Cost-per-foot analysis can help you decide which bit to use. 
* Examination of dulls can also help you decide which bit to use.


===Tripping can ruin a new bit===
*Shale has a better drilling response to drill speed.
* Make the bit up to proper torque.
*Limestone has a better drilling response to bit weight.
* Hoist and lower the bit slowly through ledges and doglegs.
*Bits with roller bearings can be run at a higher speed than bits with journal bearings.
* Hoist and lower the bit slowly at liner tops.
*Bits with sealed bearings have a longer life than bits with open bearings.
* Avoid sudden stops. Drillpipe stretch can cause a bit to hit the hole bottom.
*Bits with journal bearings can be run at higher weights than bits with roller bearings.
* If reaming is required, use a light weight and low speed.  
*Diamond product bits can run at higher speeds than three-cone bits.
*Bits with high offset may wear more on gauge.
*Cost-per-foot analysis can help you decide which bit to use.
*Examination of dulls can also help you decide which bit to use.


===Establish a bottomhole pattern===
=== Tripping can ruin a new bit ===
* Rotate the bit and circulate mud when approaching bottom. This will prevent plugged nozzles and clear out fill.
* Lightly tag bottom with low speed.
* Gradually increase speed and then gradually increase weight.


===Use a drill-off test to select best weight on bit (WOB) and speed===
*Make the bit up to proper torque.
* Select speed.
*Hoist and lower the bit slowly through ledges and doglegs.
* Select bit weight. Depending on bit selected, refer to appropriate manufacturer’s recommended maximum speed and WOB.
*Hoist and lower the bit slowly at liner tops.
* Lock brake.
*Avoid sudden stops. Drillpipe stretch can cause a bit to hit the hole bottom.
* Record drill-off time for 5,000-lbm increments of weight indicator decrease.
*If reaming is required, use a light weight and low speed.
* Repeat this procedure for different speeds.
* Drill at the weight and speed that give the fastest drill-off time.  


===The bit is not always to blame for low ROP===
=== Establish a bottomhole pattern ===
* Mud weight may be too high with respect to formation pressure. 
* Mud solids may need to be controlled. 
* Pump pressure or pump volume may be too low. 
* Formation hardness may have increased. 
* Speed and weight may not be the best for bit type and formation. Use drill-off test. 
* Bit may not have adequate stabilization. 
* Bit may be too hard for the formation.


==References==
*Rotate the bit and circulate mud when approaching bottom. This will prevent plugged nozzles and clear out fill.
*Lightly tag bottom with low speed.
*Gradually increase speed and then gradually increase weight.


=== Use a drill-off test to select best weight on bit (WOB) and speed ===


==Noteworthy papers in OnePetro==
*Select speed.
*Select bit weight. Depending on bit selected, refer to appropriate manufacturer’s recommended maximum speed and WOB.
*Lock brake.
*Record drill-off time for 5,000-lbm increments of weight indicator decrease.
*Repeat this procedure for different speeds.
*Drill at the weight and speed that give the fastest drill-off time.


==External links==
=== The bit is not always to blame for low ROP ===


==See also==
*Mud weight may be too high with respect to formation pressure.
[[Rotary drill bits|Rotary drill bits]]
*Mud solids may need to be controlled.
*Pump pressure or pump volume may be too low.
*Formation hardness may have increased.
*Speed and weight may not be the best for bit type and formation. Use drill-off test.
*Bit may not have adequate stabilization.
*Bit may be too hard for the formation.


[[Roller cone bit design ]]
== References ==


[[PDC drill bits]]
== Noteworthy papers in OnePetro ==


[[PEH:Introduction to Roller-Cone and Polycrystalline Diamond Drill Bits|PEH:Introduction to Roller-Cone and Polycrystalline Diamond Drill Bits]]
== External links ==


[[Category: 1.5 Drill Bits]]
== See also ==
 
[[Rotary_drill_bits|Rotary drill bits]]
 
[[Roller_cone_bit_design|Roller cone bit design]]
 
[[PDC_drill_bits|PDC drill bits]]
 
[[PEH:Introduction_to_Roller-Cone_and_Polycrystalline_Diamond_Drill_Bits|PEH:Introduction to Roller-Cone and Polycrystalline Diamond Drill Bits]]
 
==Category==
[[Category:1.5 Drill bits]]  [[Category:NR]]

Revision as of 12:53, 26 June 2015

Factors to consider during bit selection and operation

Some important rules to help guide in drilling bit selection are discussed below:

Rules of thumb for bit selection

  • Shale has a better drilling response to drill speed.
  • Limestone has a better drilling response to bit weight.
  • Bits with roller bearings can be run at a higher speed than bits with journal bearings.
  • Bits with sealed bearings have a longer life than bits with open bearings.
  • Bits with journal bearings can be run at higher weights than bits with roller bearings.
  • Diamond product bits can run at higher speeds than three-cone bits.
  • Bits with high offset may wear more on gauge.
  • Cost-per-foot analysis can help you decide which bit to use.
  • Examination of dulls can also help you decide which bit to use.

Tripping can ruin a new bit

  • Make the bit up to proper torque.
  • Hoist and lower the bit slowly through ledges and doglegs.
  • Hoist and lower the bit slowly at liner tops.
  • Avoid sudden stops. Drillpipe stretch can cause a bit to hit the hole bottom.
  • If reaming is required, use a light weight and low speed.

Establish a bottomhole pattern

  • Rotate the bit and circulate mud when approaching bottom. This will prevent plugged nozzles and clear out fill.
  • Lightly tag bottom with low speed.
  • Gradually increase speed and then gradually increase weight.

Use a drill-off test to select best weight on bit (WOB) and speed

  • Select speed.
  • Select bit weight. Depending on bit selected, refer to appropriate manufacturer’s recommended maximum speed and WOB.
  • Lock brake.
  • Record drill-off time for 5,000-lbm increments of weight indicator decrease.
  • Repeat this procedure for different speeds.
  • Drill at the weight and speed that give the fastest drill-off time.

The bit is not always to blame for low ROP

  • Mud weight may be too high with respect to formation pressure.
  • Mud solids may need to be controlled.
  • Pump pressure or pump volume may be too low.
  • Formation hardness may have increased.
  • Speed and weight may not be the best for bit type and formation. Use drill-off test.
  • Bit may not have adequate stabilization.
  • Bit may be too hard for the formation.

References

Noteworthy papers in OnePetro

External links

See also

Rotary drill bits

Roller cone bit design

PDC drill bits

PEH:Introduction to Roller-Cone and Polycrystalline Diamond Drill Bits

Category

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