Page 566 - Air and Gas Drilling Manual

11-4 Air and Gas Drilling Manual
(in its respective track). These dual rotary rigs can handle a variety of drill string
types and outside diameters (including dual wall pipe). When simultaneously
running casing while advancing the drill string, only internal/external flush welded
joint casing can be used.

Figure 11-3: Casing shoe ring drag type bit (carbide studded) welded to the bottom of
the casing (courtesy of Foremost Industries Incorporated).

Top Head Rotary Drive Slant Rigs
A variety of shallow drilling rigs can be used to drill a slant borehole. The
slant capability of a drill rig refers to its ability to tilt the mast to an angle relative
to the horizontal. Most slant capable rigs can slant their mast between 0˚ and 45˚
(relative to the vertical). The 0˚ angle is a vertical mast. Figure 1-1 is an example
of a shallow drilling rig that has 0˚ to 45˚ slant capability. These slant capable
small drill rigs are utilized in monitoring well construction, and in a variety of
geotechnical and mining drilling operations.
Figure 11-4 shows a trailer mounted deep drilling rig that can be slanted to
angles between 0˚ and 45˚. This rig design is known as the Sierra Model and is
fabricated by the George E. Failing Supply Company, Limited (Canada). These rigs
can utilize an integral top drive power swivel (similar to a top head rotary drive) that
is hydraulically actuated, or a rotary table that can also be slanted to match the slant
of the mast. The hoist system is of a conventional design with a crown block and
track mounted traveling block. The can use a variety of drilling fluids (e.g., drilling
mud, or air and gas drilling fluid technology). The rig in Figure 11-4 has a 73 ft