How do you choose the best drilling method for subsurface exploration?

2 Auger drilling

Auger drilling is a drilling method that uses a helical screw to penetrate and lift the subsurface materials. The screw can be either continuous or discontinuous, depending on the size and shape of the borehole. Continuous augers have a long and slender screw that rotates inside a hollow stem, which collects the subsurface materials and brings them to the surface. Discontinuous augers have a short and wide screw that rotates at the end of a solid stem, which pushes the subsurface materials to the surface. Auger drilling does not use drilling fluids, and therefore does not produce much waste or contamination. However, it also does not collect samples, and can only provide qualitative information about the subsurface materials. Auger drilling is suitable for drilling in soft and unconsolidated materials, such as clay, silt, or loose sand, and can reach depths of up to 30 meters.

3 Percussion drilling

Percussion drilling is a drilling method that uses a hammering action to break and loosen the subsurface materials. The hammer can be either driven by compressed air or by a cable, depending on the power and speed of the drilling. Air-driven hammers are attached to the drill bit, which is connected to a hollow stem that allows for the circulation of air. The air helps to remove the cuttings and to cool and lubricate the hammer and the drill bit. Cable-driven hammers are suspended from a cable, which is connected to a winch that raises and lowers the hammer. The hammer strikes the drill bit, which is connected to a solid stem that collects the cuttings and brings them to the surface. Percussion drilling can collect samples, either by using a core barrel or by using a split-spoon sampler, which is a hollow tube that splits open to reveal the subsurface materials. Percussion drilling is suitable for drilling in hard and unconsolidated materials, such as rock, gravel, or clay, and can reach depths of up to 100 meters.

4 Sonic drilling

Sonic drilling is a drilling method that uses high-frequency vibrations to advance and retract the drill bit and the core barrel. The vibrations create a liquefaction effect, which reduces the friction and resistance of the subsurface materials, and allows for the easy penetration and extraction of the drill bit and the core barrel. Sonic drilling can collect high-quality and undisturbed samples of the subsurface materials, as the vibrations prevent the mixing and compaction of the samples. Sonic drilling can also drill faster and deeper than other drilling methods, as it does not require much drilling fluid or pressure. Sonic drilling is suitable for drilling in a wide range of materials, from soft and unconsolidated to hard and consolidated, and can reach depths of up to 300 meters.