borrhålet

Borrhålet (the borehole) is a narrow shaft drilled into the ground to access subsurface fluids or to obtain geotechnical or hydrogeological information. The term is commonly used in Swedish geology and engineering to describe holes drilled for water wells, geological investigations, or monitoring installations.

Construction and methods: Drilling techniques include rotary and percussion methods, and for shallow holes auger drilling may be used. Drilling fluids or compressed air are often circulated to lift cuttings and stabilize the hole, and to cool the drill bit. Many boreholes are lined with casings to prevent collapse and to control fluid flow. In deeper work, cement or grout is used to seal joints and isolate formations.

Applications: Boreholes serve diverse purposes, including water supply wells, groundwater monitoring wells, geothermal boreholes, and mineral or hydrocarbon exploration. They are also used for geotechnical testing in construction projects such as foundations, tunnels, and dams, providing access to rock and soil properties and enabling chemical or hydraulic measurements.

Data collection and monitoring: Boreholes are equipped with sensors and logging tools to measure water level, temperature, chemical properties, pressure, and rock characteristics. The collected data support groundwater models, environmental monitoring, resource assessment, and safety planning for engineering works.

Regulation and environmental considerations: Drilling activities are governed by safety standards and environmental regulations to prevent contamination and protect water resources. Abandonment or decommissioning of boreholes typically involves sealing and backfilling to prevent leakage and to restore land as needed.