First of all, the use of the previous bit should be carefully checked. Understand the wear status of drill gauge. Inspect the bit body for any missing damage (missing parts, such as teeth, that may harm the bit that is about to be drilled).Bit stability is important to prevent deviation and maximize bit performance, so. When using a PDC bit, it is recommended that the bit be drilled in a stable operating state. However. By the specific length of drilling and the particularity of hole conditions. Sometimes there is no need to pursue textual and species stability. All stabilizers and hole punches should have their outside diameters checked to ensure that the outside diameters are not too large.
First drill of new bit:
1. When the drill bit is near the bottom of the hole, turn on the pump to its maximum displacement, and then start the rotary wheel to control the speed between 30 and 60rpm. Drill slowly until the bit touches the bottom of the hole.
2. To create a new bottom hole, the recommended starting weight on BIT should be applied during drilling the first 1m or so of the hole. The table provides starting weight on bit values for various types of bits of different sizes. The starting operating parameters (weight on bit and rotational speed) of the bit should be at least as long as one bit can be drilled.
3. Once the new bottom hole is formed, the weight on bit is increased gently and evenly until it reaches the normal weight on bit level. For extremely soft formations, this weight on bit is very close to the initial weight on bit. In harder formations, it takes longer for the bit to run in to form a new bottom hole, resulting in higher normal working weight on bit. The optimal weight on bit should be when the weight on bit reaches this value and the bit's ROP no longer increases with new weight on bit, or the bit torque has reached its limit.
4. Increase bit speed until desired level. The optimal rotational speed of the bit should be: After the rotational speed reaches this value, the ROP of the bit will no longer increase with the new rotational speed, or the bit torque has reached the limit torque value. Generally, ROP is more sensitive to changes in rotational speed when drilling in softer rock. High bit speed can easily lead to premature wear and failure of cutters in hard and abrasive formations. Therefore, it is important to monitor the bit ROP as a function of RPM so that we can achieve the desired ROP at the lowest possible RPM. Generally, the recommended bit RPM range is 60 to 240rpm.
