Tricone drilling and maximum load
Tricone bit drilling is a method of drilling rock that depends on the energy the rig and drill tool act on the roller cone bit. The energy that is applied to the roller cone bit through the drilling tool includes the turning motion and the downward thrust. The thrust is achieved by the force of the drill acting on the roller bit and by the hydraulic cylinder, wire rope or chain on the drill.
Table 1 for the daily tri-cone bit load, for large-diameter roller cone drill bits generally use the upper part or bit weight.
Under the caliber with a drill collar, with a large bucket, and add stabilizer (or righting circle).
Large-diameter cone drill bit drilling as much as possible using gas lift reverse circulation drilling, bit life and drill speed will be greatly enhanced
Table 1 Tri-cone bit maximum load
|
Bit size |
Load |
||
|
In. |
mm |
psi |
Kg/mm |
|
6 8 1/2” 9 1/2” 9 5/8” 12 1/4” |
152 216 241 245 311 |
4100 4500 6010 6050 7350
|
75 93 103 106 131 |
IADC Tricone roller cone classification system
| First Digit-1,2,3 designate steel tooth bits and the formation being drilled,with 1 for soft,2 for medium,and 3 for hard formations.4,5,6,7,and 8 designate tungsten carbide insert bits and the formation being drilled,with 4 being the softest and 8 the hardest formation. |
| Second Digit-1,2,3 and 4 are further broken down by the formation,with 1 being the softest and 4 the hardest. |
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Third Digit-Classifies the bit according to bearing/seal type and special gauge/wear protection.
1.Open Bearing-On these bits the cones will spin freely.The bit has a front row of ball bearings and a back row of roller bearings 2.Opening Bearing,Air-Cooled-Cones are similar to#1.but have air injection directly to the cones to cool the bearings.Air flows into the cone through the passage ways inside the pin.(Not for use in mud applications.) 3.Open Bearing with Gauge Protection-Carbide inserts in the heel of the cone. 4. Sealed Roller Bearing-These bits have an o-ring seal with a grease reservoir for bearing cooling.The seal acts as a barrier against mud and cuttings to protect the bearings. 5.Sealed Roller Bearing with Gauge Protect-Carbide inserts in the heel of the cone. 6.Sealed Journal Roller Bearing-These bits are strictlt oil/grease cooled with nose bearings,o-ring seal and a race for maximum performance. 7.Sealed Journal Rolling Bearing with gauge protect-Carbide inserts in the heel of the cone. |
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Fourth Digit-used to indicate additional features. A. Air Application E: Extended Jet X: Chisel Insert C: Center Jet G: Extra Gauge Protection Y: Conical Insert S:Standard Steel Tooth J: Jet Deflection Z:Other Insert Shape D:Deviation Control R:Reinforced Welds |
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Example 1: IADC Code:321 Bit Description: 3=Steel Tooth,Hard Fromations 2=Semi-Abrasive and Abrasive Fromations. 1=Open Bearing
Example 2: IADC Code:514 Bit Description: 5=Tungsten Carbide Insert,Soft to Medium Formation 1=Soft Formations 4=Sealer Roller Bearing |