RE: First casing26 Oct 2018 11:00
Drill rate depends on a number of factors. Geology, drill bit type, drill string design (weight), vertical or directional. Most drill bits are 3 cone type, they have a design weight range, too much you going to break them, too little not going to drill efficiently. The amount of weight you can put on the bit is determined by the number of collars and heavy ball pipe. The zero weight point is normally kept in the top end of the heavy ball. It’s all a balancing act, the driller will have a target weight on his guage but will play around with it for max rate. Bear in mind he also wants to keep vertical if that is the design, too much weight on the bit can cause it to kick off sideways. If the well fills with cuttings, drilling stops and hole is circulated out.