BOREWELL DRILLING METHODS
SURFACE DRILLING
Surface drilling methods are adopted in areas where the drilling location is vacant and has enough space for the drilling rig to set the point. There are various diameters of drilling bits used in surface drilling based on the usage of the borewell. As per current market situation high power rigs are equipped with a facility to drill borewells up to 1200 feet.
Domestic / Home purpose – 4.75 inch, 6 inch, 6.5 inch borewell drilling
Agriculture purpose – 6.5 inch, 8 inch, 10 inch, 12 inch borewell drilling
Industrial purpose – 6.5 inch, 8 inch, 10 inch, 12 inch borewell drilling
Borewell Drilling procedure:
Drilling procedure of a 6.5 inch borewell is been explained in our draft, the procedure is the same for all dimensions of drilling. The drilling rig is been set exactly in the point marked by a water diviner, hydro geologist, groundwater locator or a borewell point identification expert. Once the drilling rig is set in the point the 8 inch borewell drilling bit is set with the hydraulic hammer which gives pressure for the bits and is forced into the earth surface with the power produced from the high pressure compressor to blast the hole from the surface of the earth until the hard rock formation is hit.
Once the hard rock formation encounters the complete set of drilling rods along with the hammer and 8 inch bit is removed to the surface and casing pipes made of MS iron or PVC of required grade and thickness of 7 inch(6kg) diameter is been installed into the borehole which works as a wall for the borehole avoiding the soil to fall into the well.
After inserting the casing pipes 6.5 inch bit is been set with the hammer to drill the rock and is again driven into the bore hole and the rock is been drilled with a pressure based on the geological formation of the area. Normally drilling rods of measurement 20 feet each are been set for each and every 20 feet to drill all the way from the surface to the required target. When the drilling is in progress the driller or the drilling supervisor carefully watches the changes in formation for each and every foot. Usually the rock color and formation changes step by step in certain cases we also find the same rock throughout. The supervisor keeps an eye if there is some issues of silt or boulders during drilling, if silt or boulders occur during drilling special pipes called slotted or screener pipes need to be installed throughout the borewell. Once the water encounters from the borewell, it would be visibly running out from the drilled hole, approximately drilling supervisors can estimate the amount of yield from the borewell.
In case the water is sufficient the drilling process can be stopped if not it can be continued until the drilling reaches the next source. If the amount of water is high in the borewell, the borewell drilling cannot be processed
Issues:
• Always do not construct any kind of storage tanks or septic tanks near the borewell as it may result in contamination of the well.
• If the borewell are not cleaned at least once in two years it may result in blockage of sources.
• Gelatin blasting in borewell may end up in complete collapse of the well.
• Usage of borewell without installation of slotted casings in silted and boulder conditions may collapse the well, motor may get struck, issues in pumping may occur.
