The Flame Jet Drill is a type of drilling equipment

Drilling rig

A drilling rig is a machine which creates holes or shafts in the ground. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells, or they can be small enough to be moved manually by one person...

 whereby there is no contact with the drilling surface, therefore the drill never wears down.

The tool expels an ultra hot hydrogen flame (~4000 °C) which causes small inconsistencies in the rock

Rock (geology)

In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...

 to fracture

Fracture

A fracture is the separation of an object or material into two, or more, pieces under the action of stress.The word fracture is often applied to bones of living creatures , or to crystals or crystalline materials, such as gemstones or metal...

 and fly away and thus "drill" surface.

Another prototype drill called a Hydro Jet Drill is able to work in hot damp conditions by superheating

Superheater

A superheater is a device used to convert saturated steam or wet steam into dry steam used for power generation or processes. There are three types of superheaters namely: radiant, convection, and separately fired...

 water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 and spraying the rock with the fluid.

The devices were featured in a National Geographic documentary "MegaStructures: Deep Earth Drillers" about geothermal energy.