Water is life, essential for human existence, and its importance for individual health cannot be overemphasized. It is equally vital for the well-being of a nation, and access to good quality water is imperative.
A borehole is a hydraulic structure that permits the economic withdrawal of water from an aquifer. In Nigeria, a borehole is a major source of water. There is manual digging (done by hand) of wells. Drilling actually means making a hole. On the Earth’s crust, there are fractures known as formations, and in these formations are located regions referred to as aquifers (a water-bearing formation).
Making a borehole (mechanized drilling) for obtaining natural water from the ground is done by drilling through the cracks, fractures, and aquifers found in the Earth’s formation. Hence, when someone wants to drill a borehole, a machine known as a rig is used. As the drilling takes place, the rod passes through all the layers of the Earth’s crust, continuing to make a hole inside the rock until it reaches the area where there is a crack. When the rod hits the crack, water begins to flow out, making it important to note that 90% of cracks on the ground have water.
In the drilling business, carrying out a survey (also known as a physical survey or sounding) is the first necessary step to get information about the location and to ascertain the position of cracks, also called fractures (a place where there is a water log), and make decisions on price, types of formations, and availability of water in the crust. Then, the rig is brought to the site, and a rod is pierced into the ground. It keeps going down until it hits a crack (fracture), and once there is water, it bursts and flows through the hole, and water begins to come out using a compressor. If the process continues, the rod could get to another level of fracture, which then bursts and more water comes out. Finally, when water has been located, the rod is removed, and the hole remains, and as such, water will flow through the hole to the surface.
TYPES OF FORMATIONS
BASEMENT FORMATION
Basement refers to a rocky or stony hard surface characterized by a very rigid surface, located in the far north and Abuja. There can be water at different levels of the Earth’s crust but is easy to drill. The hole can stay put while drilling but can be suspended with casings. It takes about 3-5 hours to drill, and a compressor is used for drilling. A compressor (a machine that produces air and is used for hitting the rock with a hammer) uses air to drill and is referred to as ‘air drilling’. It is quite noisy (loud) when drilling.
SEDIMENTARY FORMATION
A sedimentary surface is one that is characterized by sandy soil, located mostly in the eastern and western parts of Nigeria. This is made possible because of its proximity to the ocean and water fronts. The soil is very soft and flexible. There is always water available in the ground but quite difficult to drill because of the loose soil nature. The cost of drilling is more expensive and takes a longer period to drill because the soil keeps falling back when drilling. It can take up to 2 weeks to complete the drilling. A mud pump is used for drilling in this environment.
It is important to note that during conducting a survey, information from at least two points, Vertical Electrical Sounding (VES 1) and Vertical Electrical Sounding (VES 2). Both points are compared to determine the best location for drilling. A key term used in the survey is ‘Versatility,’ which refers to the thickness or strength of the formation and is measured in Ohms. The values obtained from Versatility indicate the softness or hardness of the surface. When the value decreases, it means the soil is getting softer, and when it is in ascending order, the crust is becoming harder. However, there is usually a comparison between VES 1 and VES 2, which helps give a recommendation and ultimately assists in interpretation.
In Nigeria, a household name in drilling and water provision is Techno Santo Mezel Nigeria Limited, an indigenous borehole drilling company specializing in all sizes of boreholes for domestic and commercial purposes. They are capable of drilling up to 500m on any solid formation, providing drilling services with integrity all over Nigeria since 2001. They also maintain and rehabilitate old and existing boreholes.”
