The deep formation has a high degree of hardness and abrasivity; the bit type selection is difficult and the ROP is low especially under the high density mud.
深部井段地层的硬度高、研磨性强，钻头选型困难，特别是在高密度条件下机械钻速低。
2
This instrument, simple in structure and of multi-function, may be used to measuring the drillability and abrasivity of rocks, and simulate rotary or rotary-percussive drilling as well.