• In drilling the main forces concerened with the drill string are tension and torque.

 

• One of the main issues is making sure that the tension of the drill pipe is significant enough, so no weight is placed on the drill bit. By placing weight on the drill bit there force being placed on the whole drill pipe. There progressively more force placed on the drill string the deeper the drilling occurs. So buckling will occur.

 

• When buckling occurs the drill pipe is bent out of shape causing the string to "corkscrew."

 

• Another issue involved with drilling, is the torque placed on the drillstring. The drill-bit must be making significant progress through the rock formation so that the pipe does not have too much resistance to circular motion. The motor has enough torque that, if the bottom of the drill pipe is not making the same circular progress as the top, the pipe may twist and shear.