Structural features and instructions for roller cone bits（tricone bits）
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As a tool for drilling rock formations, the dramatic improvement in the performance of roller cone bits directly reduces drilling costs, and the two performance indicators of service life and drilling speed determine the extent of the impact of the drill bit on drilling costs. In recent years, people have gradually realized that the diameter-maintaining structure also has a great impact on the ROP and life of the drill bit. Especially in highly deviated wells and horizontal wells, a reasonable diameter-maintaining structure is needed, and many new diameter-maintaining structures have been developed. Came out and applied to roller cone bits, and achieved good results. The following are the structural features and instructions for use of roller cone bits.
First, the structural characteristics of roller cone bits:
1. The roller cone bit adopts high-strength, high-toughness cemented carbide teeth, which improves the impact resistance of the teeth and reduces the damage rate of the teeth.
2. Through the optimized design of the number of teeth, the number of teeth, the height of the teeth, and the unique shape of the alloy teeth, the cutting ability and cutting speed of the drill can be fully utilized.
3. It adopts spring locking cone to withstand higher drilling pressure.
4. The inner hole of the cone is welded with anti-wear alloy to improve the anti-seizure ability of the bearing.
5. High saturation rubber O-ring is used to optimize the sealing compression and improve the sealing reliability of the bearing.
6. The all-rubber oil storage bag is used to limit the pressure difference, prevent the drilling fluid from entering the lubrication system, provide good lubrication for the bearing system, ensure the normal operation of the "O" seal, and increase the working life of the drill bit.
7. The use of a new type of grease resistant to high temperatures of 250°C and low wear is used to improve the high temperature resistance of the drill bit sealing lubrication system. When used at normal speed, it can withstand higher drilling pressure.
Second,Instructions for use of roller cone bit:
1. After the drill bit reaches the bottom of the well, it should be run with light pressure for about 0.5h, and then gradually pressurized to the required WOB. It is strictly forbidden to start the turntable under pressure. When operating the brakes, you must concentrate your thoughts and feed the drills evenly to prevent slipping and stalling accidents.
2. When drilling, it is necessary to analyze and grasp lithological changes at any time according to the changes in drilling time and bit operation, and adjust parameters to meet the needs of the drilled formation. Master the tripping time. Under normal circumstances, the working time of the drill bit depends on the life of the drill teeth and bearings.
3. Judging that the drill bit shrinks and the screw supports cutting the well wall: the torque of the turntable increases, the well is drilled, and the rotation speed of the turntable changes greatly. The rotating speed of the turntable changes uniformly in a wave shape on the curve, the torque does not increase, and the slow decline does not send the drill. The drilling pressure is low and the rotation speed is low, and the down the hole detention cannot be relieved. The lithology does not change during drilling, but doubles. After the pump is stopped, the drill tool is lowered without obstacles, and there is no large rock cuttings at the vibrating screen. It can be analyzed that the drill bit is reduced in diameter and the screw supports cutting the well wall.
4. Judging the damage of roller cone bit bearing: re-pressurizing, the torque and the rotating speed of the turntable are different, sometimes very stable. Sometimes the torque fluctuates abnormally; the pointer of the weight meter swings when re-pressurizing. The torque of sandstone formations is greater than that of mudstone formations, and changes frequently in a small range, while mudstone formations are relatively stable.
5. Judge whether there is a large piece of cuttings that cannot be returned from the borehole: the rotary table torque amplitude changes greatly during drilling, the large pieces of cuttings are returned, the spiral armature has different degrees of wear, and the water pump is stuck when the drill is lifted, and the well is broken. The torque of the turntable increases when the leak or well collapses, and the down the hole is crappy.
