The University of Drilling is a practical learning site, not an accredited school.

Figure A: Drill Stem

As described in API 7-1 and ISO 10424-1: (working from the bottom of the drill string upward) holes are bored with a bit (A:1) which is connected with a rotary pin connection (A:2) to a rotary box connection (A:3) of a bit sub (A:4) which uses rotary pin and box connects to drill collars (A:5) and crossover subs (A:6) to a series of drill pipe having a lower tool joint pin end (A:7), pipe body (A:8) and upper tool joint box end (A:9) extending to surface where it is rotated by and connected to either a kelly drive or a top drive.

A kelly assembly can have a lower kelly valve or kelly saver sub (A:11) with a rubber protector (A:10) screws into the lower kelly upset connection (A:12) of the “square” kelly drive section (A:13) having an upper kelly upset which connects to the upper kelly valve (A:15) and the double pin end swivel sub (A:16) that engages the box of the swivel stem (A:17) at the lower end of the swivel (A:18).

The kelly assembly can be replaced by a top drive assembly which is similar to a home hand held drill, except much larger.