borehuller

Borehuller are drilled holes made in the earth to access subsurface resources or to gather subsurface information. The term is used in Danish and Norwegian and is commonly translated as boreholes in English. Borehuller vary greatly in size, depth, and purpose, from a few meters for domestic water to several kilometers for oil, gas, or geothermal projects. They may be vertical or inclined.

Drilling techniques include rotary drilling, percussion (hammer) drilling, and auger drilling. Most production boreholes are lined with casing and sealed with cement to prevent collapse and to isolate different subsurface layers. Drilling fluids, or muds, help stabilize the hole, carry cuttings to the surface, and control formation pressures. In some cases, open-hole construction is used for logging or testing before casing.

Applications cover water supply, mineral and hydrocarbon exploration, geothermal energy, environmental monitoring, and storage or waste disposal wells. Before drilling, planners consider geology, groundwater, surface conditions, permits, and environmental impact. After drilling, boreholes are completed by installing casing or screens, performing tests (flow tests, grouting), and conducting borehole logging to characterize the subsurface. The well may be tested for yield, water quality, or reservoir properties.

Decommissioning or abandonment involves permanently sealing the borehole to prevent cross-contamination or subsidence, following regulatory requirements. Borehuller play a critical role in resource extraction, groundwater management, and subsurface research, while also presenting environmental and safety challenges that require proper planning and management.