Page 27 - Air and Gas Drilling Manual

1-4 Air and Gas Drilling Manual
Rotary drilling is carried out with a variety of drilling rigs. These can be small
“single” rigs, or larger “double” and “triple” rigs. Today most of the land rotary
drilling rigs are mobile units with folding masts. A single drilling rig has a vertical
space in its mast for only one joint of drill pipe. A double drilling rig has a vertical
space in its mast for two joints of drill pipe and a triple drilling rig space for three
joints. Table 1-1 gives the API length ranges for drill collars and drill pipe [6].
Table 1-1: API length ranges for drill collars and drill pipe.
Ranges Minimum Length (ft) Maximum Length (ft)
Range 1 18 22
Range 2 27 30
Range 3 38 45
Figure 1-3 shows a typical single drilling rig. Such small drilling rigs are
highly mobile and are used principally to drill shallow (less than 3,000 ft in depth)
water wells, environmental monitoring wells, mining related boreholes, and other
geotechnical boreholes. These single rigs are usually self-propelled. The self-
propelled drilling rig in Figure 1-3 is a George E. Failing Company Star 30K.
These rigs typically use Range 1 drill collars and drill pipe.

Figure 1-3: Typical self-propelled single drilling rig (courtesy of George E. Failing
Company).