Drilling has existed as an industry since the Chinese erected the first cable-tool rig approximately 4000 years ago. Since the development of drill rigs, techniques and applications have led to the industry’s expansion multiple specialised sectors. Definitions of each drilling sector follow, along with brief outlines of the applications involved. Processes and spheres of influence overlap in many cases.
Blast hole drilling
Holes are drilled for explosives, which are detonated to remove rock, ore, or minerals. The sector covers:
- Mines where surface and underground drilling is part of the extraction processing for valuable ore, including the removal of waste to access the ore body.
- Quarries to produce road or construction materials and dimension stone.
- Construction of roadworks, dam sites, and breakwaters.
Environmental drilling
This industry sector uses specialised geotechnical drilling and water well drilling methods to:
- Monitor the quality of groundwater and assist in the control and remediation of groundwater pollution.
- Test and monitor landfill sites, pollution of lagoons and sensitive sites (e.g. protected land, water supply well fields, chemical, or hydrocarbon storage sites).
- Determine the source or extent of pollution problems.
- Sample and construct wells for recovering or remediating pollutants in groundwater.
- Support work at archaeological sites.
Geotechnical investigation
This type of drilling is carried out to determine soil and rock characteristics. In some cases, it is also used to gather information about the nature and position of the water table from particular sites. Drilling is conducted to assess potential construction sites and to confirm conditions. It is important to have detailed information about soil and rock properties obtained from Geotechnical drilling so that buildings or tunnels are not placed on top of, or cut through, unstable or weak material. Geotechnical drilling precedes construction, and Foundation and Construction drilling.
Geothermal drilling
This industry sector uses drilling to generate electric power from steam turbines, which are powered by steam that is produced from hot water recovered from the drill holes. There are two main types of hydrothermal deposits:
- Hot water springs.
- Hot rocks.
Hot rocks require injection wells as well as production wells. Water is injected into the ground, where it is heated by the rocks and then recovered from the production wells.
Mineral exploration drilling
This industry sector uses drilling to search for valuable minerals or materials. Drilling is conducted to:
- Search for new ore bodies.
- Determine the size and grade of an ore body (resource definition).
- Collect stratigraphic information.
- Carry out geochemical surveys.
- Perform gravity or magnetic survey interpretation enhancement.
- Undertake grade control (i.e. determine what is uneconomical to treat and then drill to identify what can be treated during the mining process).
- Check that no economic ore or materials are below sites for a proposed waste dump, dam, plant, or building (sterilisation drilling).
- Explore for ore bodies.
