High-flow air is injected through the drill string, cooling the bit, evacuating rock cuttings from the borehole and stabilizing the borehole during drilling. The air-rotary technique is much more efficient than other rock drilling techniques (i.e. cable tool) because the high-flow air constantly cleans the bottom of the borehole, which allows for consistent contact between the drill bit and intact bedrock. The size of the air compressor and borehole determine the achievable depth, since the compressor must maintain an up-hole velocity of approximately 3,000 feet per minute to effectively remove the drill cuttings. In bedrock formations where cuttings removal is more difficult, foam can be added to the injected air to increase the viscosity and help lift cuttings from the borehole.
The following are rigs in Hawk's fleet that offer the Air Rotary drilling method. Click to learn more details about their capabilities and respective advantages:
Drilling mud is injected through the drill string, cooling and lubricating the bit, carrying the cuttings to the surface to be deposited in either a mud tub or pit, permitting the removal of the cuttings from the mud at the surface. The drilling mud will clean out the bottom of the borehole, deposit an impermeable wall cake, overcome formation fluid pressures, and prevent caving of the borehole walls. The drilling mud will avoid damage to productive water zones, allow for interpretable electric well logs to be obtained, and protect the drill pipe against corrosion.
The following are rigs in Hawk's fleet that offer the Mud Rotary drilling method, click to learn more details about their capabilities and respective advantages:
Hollow Stem Auger
For normal hole advancement, a pilot bit is inserted through the cutter head to drill the center of the hole. The drill rod is bolted to the inside of the drive cap with a rod-to-cap adapter so that the pilot bit can turn in tandem with the augers. This method allows for split spoon sampling, Shelby tube sampling, Dennison sampling, Hydropunch discrete water sampling, and rock coring to be performed while leaving the augers in place.
Drill rods are normally added each time an auger is added. In soft formations (dirt and sand), a tapered wooden plug may be inserted into the end of the cutter head to prevent material from going up inside the augers and eliminates the use of drill rod. When the hole is completed, the plug may be knocked out the bottom of the auger string. The next step is to insert the monitoring screen and casing, which is then grouted into place to prevent contamination from the top of the hole.
The following rigs in Hawk's fleet that offer the Hollow Stem Auger drilling method, click to learn more details about their capabilities and respective advantages:
Hawk Drilling’s drilling services also include exploratory rock coring. This technique gathers high quality cylindrical samples that allow geologists to determine the composition of the rock lying underground. Wire line methodology, which leaves the drilling string intact while bringing the rock core to the surface with a wire ensures the least amount of contamination and most efficient gathering of samples.
Rock core drilling with water allows us to retrieve five-foot continuous samples of bedrock formations.