Reasonable Use of Roller Cone Drill Bits

Roller cone drill bits runout is usually caused by worn drill bits, improper cutting fluids and insufficient clamping force. Wear on the drill head and cutting edge can cause runout. The solution is to regularly replace worn drill bits and use the correct coolant and cutting fluid. Too little or too high a concentration of cutting fluid can also cause runout. The flow rate of cutting fluid should be increased and the correct concentration should be known. In addition, insufficient clamping force can also cause the drill bit to jump, and it is necessary to increase the clamping force to ensure that the drill bit is fixed and stable. 

To ensure that you can use the roller drill bit properly, the reasonable usage method of the roller drill bit is provided for your reference to avoid problems in future operations:

(1) According to the drillability value of the stratum and refer to the stratum of neighboring wells, choose the drill bit with more footage, fast speed, low cost and normal wear. In the upper soft stratum (drillability grade value less than 5), you can choose the milling bit with high mechanical drilling speed, and in the deep section of the stratum (drillability grade value more than 5), you can choose the set-roller cone drill bits with more footage. 

(2) In the formation with easy well inclination, the roller cone wheel offset is small, and the roller cone drill bits with many roller cone and short roller cone is used. 

(3) The bottom of the well should be clean and free of fallout.

 (4) The drilling speed should be slow, to prevent stagnant drilling. When the drill bit is 1 single root at the bottom of the well, open the pump and rotate the drill bit to fully wash the well and remove the rock chips at the bottom of the well, so as to avoid clogging the nozzle with the rock chips too quickly or opening the pump too violently to hold the leakage of the stratum. 

(5) After the drill bit touches the bottom of the well, run the drill bit under low drilling pressure and low rotational speed (drilling pressure of 10~30kN, rotational speed of 60r/min) for more than 0.5h, and then gradually increase the design value of drilling pressure and rotational speed after making a good shape of the bottom of the well. 

(6) Do a good job of drilling test, i.e., fix the drilling pressure and change the rotational speed, or fix the rotational speed and change the drilling pressure, so that the drilling pressure and rotational speed are reasonably matched to achieve high drilling speed drilling. 

(7) Drilling should try to improve the pump pressure, increase the water power of the drill bit, give full play to the interaction of hydraulic parameters and mechanical rock-breaking parameters to improve the efficiency of rock-breaking. 

(8) Use the combination nozzle to improve the efficiency of rock clearing. 

(9) Better to be recommended by the manufacturer of the drilling pressure and speed of the product of the constraints, can not be used at the same time the highest drilling pressure and the highest speed. 

(10) Drilling in the operation of smooth, uniform delivery of drilling, prohibited fierce lift and release, slip and stutter drilling. 

(11) If the drilling is not caused by the ground equipment, the drill should be started immediately to avoid dropping the roller cone.

(12) From the beginning of the drill bit into the drilling, must be done with the drilling cost calculation, as long as found in a few consecutive points when the cost increases, should start drilling.