Practical Steps Involved in Drilling a Borehole

The world seems to be evolving fast. The use of hand dug wells seems to be going into extinction. From simple shopping complexes to shopping plazas, Private houses to Estates and even in Office setups, factories and even our farms, we can see the rapid ways by which boreholes are being springing up.

Base on this, it will be in our own personal interest to know about some things that are associated with borehole drilling since in one way or the other, we will definitely interact with it.

Firstly, let me take us back to some activities that take place before borehole is being drilled.i.e Prognosis to Borehole drilling.

This is prognosis is called Geophysical Investigation. Some people called it Geophysical survey. Over the years, I have received numerous number of calls asking about price for drilling a borehole and my response is always have you conducted a geophysical investigation on your site? Do you have the Geophysical report with you?
The Clients questions were like, whats do you mean by Geophysical Investigation? My neighbor already have a borehole drilled on his site and it cost #80,000, My neighbor's borehole depth is 50m, why will my own be different. From your past experience in that area, do you still need to conduct a geophysical investigation before drilling?

The short response to these is that...You need to know that the subsurface is not uniform. And changes deep down is not predictable. Hence your neighbor's borehole properties might be absolutely different from yours. And as you know, drilling its self is not always 100% successful. There is always a risk factor, so not conducting a geophysical investigation is just like increasing the drilling risk factor. Please note Geophysical investigation is always charged separately and you can consult an independent Geophysicist to carry it out for you.


After the Prognosis exercise/Geophysical Investigation now comes the drilling proper.

It is From the Investigation, you would have the idea of the drilling architecture and likewise the financial implications. The architecture will talk about the exact point to drill, the likely depth to drill and the formations/rocks to encounter with their various thicknesses. All these is what will determine the eventual financial implication for drilling the hole.
The drilling is most times charged per meter or as a lump sum depending on the technicality involved and the firm handling the project. The Drilling could be full casing or hanging depending on the nature of the subsurface. You should know that will also affect the cost.

After drilling, the hole should be properly flushed and decontaminated and also gravel packed(Grouting) and properly cased. This is called Borehole completion and expert experience is needed here as any loophole could destroy any good work that has been done so far.

Next is Pump Installation. The type of pump to use depends on the depth and yield of the borehole. The yield can be know from test pumping. Most times its assumed while drilling is on when compressor is being used.


After the pump has being installed, provision should be made for its security if the place is well open and not secured.