Page 69 - Air and gas Drilling Field Guide 3rd Edition

60 CHAPTER 4 Downhole Equipment

ROTARY BOX SWIVEL ROTARY BOX TOOL JOINT
CONNECTION L.H. CONNECTION BOX MEMBER
SWIVEL STEM
ROTARY PIN DRILL PIPE
CONNECTION L.H. SWIVEL SUB
STD 8A
ROTARY BOX
CONNECTION L.H.
STD 7 TOOL JOINT
KELLY COCK PIN MEMBER
(OPTIONAL) ROTARY PIN
ROTARY PIN
CONNECTION
CONNECTION L.H.
ROTARY BOX
ROTARY BOX CONNECTION CROSSOVER SUB
CONNECTION L.H. ROTARY PIN
UPPER UPSET CONNECTION
ROTARY BOX
CONNECTION DRILL COLLAR
KELLY
NOTE: (SQUARE OR HEXAGON)
ALL CONNECTIONS (SQUARE ILLUSTRATED)
BETWEEN “LOWER
UPSET” OF KELLY
AND “BIT” ARE R.H.
ROTARY PIN LOWER UPSET ROTARY PIN
CONNECTION KELLY COCK or CONNECTION
KELLY SAVER
ROTARY BOX SUB ROTARY BOX
CONNECTION CONNECTION
BIT SUB
PROTECTOR ROTARY BOX
RUBBER CONNECTION
ROTARY PIN
(OPTIONAL)
CONNECTION ROTARY PIN BIN
CONNECTION
FIGURE 4-1. Standard rotary drill string for direct circulation.

The number of drill collars in a drill string depends on how much weight on
bit (WOB) is required to allow the drill bit to be advanced efficiently (drill
string design is discussed in Section 4.6). The drill pipe and collar lengths are
in accordance with the range designations of Table 2-1 [1].
Generally the drill collars in a drill string have the same thread design. Above the
drill collars are the drill pipe joints. The drill pipe joint lengths are also in accor-
dance with the range designations of Table 2-1. The threads of the drill collar con-
nections are usually not the same as the threads of the drill pipe joint connections
(tool joints). Therefore, a special crossover sub must be used to mate the drill collars
to the drill pipe. The crossover sub is a short thick-walled pipe with a threaded pin
down (with the drill collar threads) and a threaded box up (with the drill pipe