Well Digging Tools

Drill Rig Basics

• In the residential water well digging trade, the term "drilling rig" refers to truck- or trailer-mounted drilling equipment. Regardless of drill type, most rigs consist of a truck or trailer bed that holds a drill engine, mast and drill attachments. Alternatively, many equipment manufacturers offer drill rigs that attach to general purpose tractors. The largest truck-mounted drill rigs resemble 18-wheel trucks. Small, trailer-mounted rigs are sometimes lightweight enough for towing by large pickup trucks. Prices for well-drilling rigs generally range from the low ten thousands to hundreds of thousands of dollars. However, equipment yards often rent tractor- and trailer-mounted drill rigs.

Rotary Drill

• A rotary drill rig's bit sits at the end of a series of connected tubes. Like a handheld power drill, the rotary drill's bit rotates to bore through material. A lubrication and flushing fluid, called mud, circulates through the drill's tube and forces debris to the top of the hole. Additionally, the fluid lubricates the bit, prevents the bit from overheating and stabilizes the sides of the hole.

Cable Tool

• Although a cable tool rig appears similar to a rotary rig at first glance, the cable tool rig bores through the earth without a drill bit. The cable tool rig consists of a chisel-like tip attached heavy metal cable. To cut through the earth, the rig repeatedly lifts and drops the chisel-like tip against the ground. Cable tools can fit into tight or unusual shaped spaces, such as crevices, inaccessible to other types of rigs. However, cable tools do not flush the well shaft during pounding and drillers must occasionally stop digging to bail out the shaft. Thus, cable tools are generally the slowest type of well digging tool.

Air Hammer

• Attached to a drill pipe like the rotary drill, the air hammer or "downhole" hammer rig pounds the ground with a chisel-like tip. Like a jack hammer, the air hammer employs pneumatic force to pound and crush through the well shaft. An air hammer's tip usually rotates at a slow rate to ensure that the tip hits a new area with each strike. Air hammer rigs are powerful and considered effective for drilling through exceptionally hard rock.