1. Drill bit selection

　　For soft formations, a steel tooth or insert bit with a combination of shifting, super-top, compound taper, large tooth profile, and the small number of teeth should be selected to give full play to the shearing and breaking effect of the bit. As the hardness of the rock increases, the drill bit of the DTH drill pipe should be shifted, over-topped, and the compound taper value should be reduced accordingly, and the teeth should be shortened or densified accordingly; abrasive formations are particularly easy to wear the gauge teeth and back cones of the cones. And the tip of the tooth, to make the drill bit diameter smaller, the borehole diameter reduction and sealing failure, should choose the special gauge structure strengthened on the back of the palm; for the anti-deflection drilling in the easily deviated formation, the drill bit should be selected without shifting the axis or with a small shifting amount. To reduce the bit slip at the bottom of the well and prevent the good deviation; For formations with alternating soft and hard, the bit-type of the harder rock in this set of formations should be selected.

　　2. Drilling situation analysis

　　DTH drill pipe surface equipment operation, cuttings and weight on bit, torque, ROP, pressure, and other surface instruments can directly reflect the downhole conditions and should be closely watched, especially the torque, pump pressure, ROP, and cuttings.

　　The torque change depends on the bottom hole conditions and speed changes. The normal torque value is relatively stable. The torque value is relatively low in soft or plastic homogeneous layers, the torque value of medium-soft to medium-hard homogeneous layers is in the middle, and the torque value of hard formations is large and has a certain range. Fluctuations. Torque changes may exist: centralizer scratches, drill bit gauge wear, interlayers, falling objects at the bottom of the well, keyways or doglegs in the well, excessive drilling pressure, changes in speed, drilling bits or bottom assembly mud packs, drilling With puncture leak or dry drill, etc.