Page 99 - Air and Gas Drilling Manual
P. 99
Chapter 3: Downhole Equipment 3-27
Figure 3-22 shows a “tapered” drill string with a drill bit at the bottom, drill
collars above the drill bit, heavy-weight drill pipe above the drill collars, and
standard drill pipe above the heavy-weight drill pipe.
Figure 3-22: Typical tapered drill string using heavy-weight drill pipe (courtesy Smith
International).
Heavy-weight drill pipe elements are used in a number of applications in rotary
drilling. Since this drill pipe can be used in compression, this drill pipe can be used
in place of drill collars in the shallow wells with small single or double rotary
drilling rigs. This drill pipe is also used in conventional drill string for vertical
drilling operations as transitional stiffness elements between the stiff drill collars and
