Recognising the importance that groundwater holds for residences, commerce and industry alike has led to an increase in borehole installations. Drilling a borehole is not as simple as selecting an area on your property in the hopes that a water table will be intersected during the drilling process. Upon the initial planning, surveys need to be conducted before Aqua Boreholes selects a suitable method of drilling to ensure the most successful result.
It All Starts with Geology
Just as you would rely on the advice of a land surveyor before building a home, Aqua Boreholes must ascertain the availability of groundwater on the property and that the groundwater will be able to sustain the intended borehole use before drilling can start. As geology controls and determines the yield of boreholes and the quality of water, it is the starting point when drilling a borehole. Detailed geological maps together with a geologist’s field mapping and further geophysical techniques and surveys will delineate drill targets.
Main Methods Used for Borehole Drilling
- Cable Tool Drilling
Considered the earliest method of drilling, cable tool drilling equipment consists of five main components to ensure a successful drill. Best used to drill through harder materials, such as rock, the stability offered by cable tool drilling ensures a steady drilling process through the lifting and lowering of suspended solid steel drilling tools. The cable tool bit is used to crush the rocks as it drills through consolidated formations. What affects the performance of this drilling method is the resistance of the rock, the dip of the rock structure, the weight and stroke of the tools, the clearance as well as the density and depth of the slurry. In unconsolidated drilling formations, the drilling action is largely a loosening and mixing process and crushing only takes place when a large rock or boulder is encountered. Some of the main advantages of drilling a borehole using this method include:
- Rigs are simplistic in design and relatively inexpensive.
- These machines require little energy to operate.
- Reliable samples can be taken from varying depths during the drilling operation.
- The drilling rig can be operated in inaccessible terrain and on properties where space is limited.
- Air rotary drilling
Used for a variety of geographical formations, air rotary drilling has the distinct advantage of producing maximum penetration at higher speeds. Where other drilling methods rely on liquids, gases are used to cool the drill bits and lift the rock cuttings out of the wellbore through high-pressure circulated air.
- Mud rotary drilling
Mud rotary drilling is used in areas where there are loose formations. Drilling mud which comprises a mixture of water, bentonite clays, polymers and other additives is used as the circulation medium. This commences by pumping the drilling mud down the drill pipe and out through a nozzle in the bit carrying the cuttings through the hole to the surface where the mud is re-used. Mud rotary drilling is best suited for areas where air rotary drilling is prohibited such as bedrock, gravel zones and sand and gravel strata. The benefits are:
- It is considered one of the most efficient methods of drilling.
- It can be acceptably used in a variety of soil conditions.
- It is stabler than the rotary air method, providing more support for completed well construction.
- It allows for larger diameter boreholes to be tapped faster and easier.
- Down-the-hole drilling
The down-the-hole method of drilling transitions from dirt to rock borehole drilling with the addition of a compressor and hammer to the drill bit. This has made it easier and faster to drill boreholes. Used in hard rock drilling, it has enabled water bores to be drilled from fractured hard rock aquifers. The advantages involve:
- It makes adapting to a directional drill quick and easy.
- It lowers operational costs as the same drill can be used for dirt and hard rock.
- As compressed air is the medium, it is more cost-effective.
- Rigs are lighter making them easier to set up and take down.
- Less time is used as there is no changeover in the drilling mechanisms.
The groundwater development must be done correctly, including selecting the drilling position, the drilling methods, yield tests and installing the infrastructure, to ensure that your borehole investment lasts.
Superb-quality Full Turnkey Borehole Solutions
Situated in Johannesburg, Aqua Boreholes services over 500 domestic, commercial and corporate clients in Gauteng and surrounding areas. Contact us and we will arrange a site inspection at no cost to you to determine the size of drilling equipment that we need and your specific requirements when drilling a borehole. For domestic, commercial or industrial borehole drilling, we have the equipment and expertise to complete the project.
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