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A water borehole is not just a hole in the ground. It has to be properly designed, professionally constructed, and carefully drilled. Boreholes for extracting water consist essentially of a vertically drilled hole a strong lining to prevent the collapse of the walls such as steel casing, which includes a means of allowing clean water to enter the borehole space and surface protection, and a means of extracting water.

In a similar manner to geotechnical and environmental drilling, exploration and investigation drilling is primarily an informationgathering exercise. When working on any mineral exploration programme the driller’s objective is to recover the maximum amount of information (e.g., core, samples, drilling data) in a form required by the client or geologist.

In sand and clay formations, the mud rotary method is used. It is a specialized method that allows us to drill through the sand and leaves the hole open for casing installation. A screen is placed opposite the targeted horizon to allow the water to flow into the hole. Between the screen and coarse sand, a filter pack is inserted to prevent any fine material flowing back into the hole.

In problem formations like riverbed and highly fractured formations, it might be necessary to install the casing as the drilling continues, as the formation keeps collapsing and it prevents the casing to
be inserted normally. Once the problem area is cased-off and the solid rock formation was penetrated, normal percussion drilling can continue to the required depth. The hole can then be cleaned and developed for pump testing and pump installation.

Angled holes are drilled at a predeterminate angle into the Ore Bodies so that better samples of the mineralization can be taken. Angled holes are drilled to the client’s needs.

Primary cementing is a critical procedure in the well construction process. The cement sheath provides a hydraulic seal that establishes zonal isolation, preventing fluid communication between producing zones in the well and blocking the escape of fluids to the surface. The cement sheaths also anchor and support the casing string and protect the steel casing against corrosion by formation fluids. Failure to achieve these objectives may severely limit the well’s ability to reach its full producing potential.

Rotary drilling is a drilling method where a sharp, rotational drill bit is used in order to make its way through various degrees of surface hardness. Rotary drilling is one of the most effective and prevalent methods used in various industries, including construction and mining. Clay cutters: Drill bits which are specially designed for use in soft surface areas, such as sand, clay, or even soft rock. Tricones: This type of bit is capable of handling a wide range of different rock formations including soft, hard, and everything in between. Augers:
Augers are generally used for drilling holes in deep foundation piles.

This system is used to identify ore bodies and consists of drilling with a Core Barrel that is flushed with air and backwashed with fluids. AIR CORE is drilled from 70mm – 250mm in diameter. Normally Coal targets are explored with this system.

Percussion Rotary Air Blasting is a drilling technique that makes use of Pneumatic pressure to drive the steel drill bit into the ground in order to create a hole. It is a hammer-like process that is easily able to penetrate rock in order to find mineral and Ore Deposits. The drill bits used are hollow. The debris which results from the drilling process shoots out of the earth and lands next to the machine, by use of air compression.

A video survey enables full inspection of the inside of a borehole to be carried out, from top to bottom, in ‘real time.’ Side views allow casing or screen condition to be observed at accurate, recorded depths. With information of this quality, problems can be identified, and complete rehabilitation of a borehole planned. Construction details can be observed directly and compared with the original log if one is available. Objects or debris dropped into a hole can be inspected and the possibility of removal assessed. Water cascades, and to a certain extent, can be viewed on a television monitor, laptop, or desktop.

Large diameter holes are drilled then filled with reinforcing and concrete. Typical uses are in the building industry and tower foundations for anchors.