Construction of Open Wells
How to construct water wells?
A water well is a lot more than a drilled hole, but for many people, the above ground part of the drilling process is the only part they see. A water well is a specially engineered hole in the ground;
For ground water monitoring, or for scientific research purposes, wells may be drilled in a way that allows the specialists to closely examine the rock formations and take frequent water samples.
Augured wells and diamond core drilling are drilling techniques often used for scientific purposes.
Most home wells are drilled to 8 or 6 inches in diameter. Municipal or irrigation wells are likely to be drilled at larger diameters, sometimes as much as 24 inches or more.
Types of well drilling methods
Three methods typically used for drilling water wells are rotary, air hammer and cable tool
In rotary drilling, a drill bit is attached to a length of connected drill pipe. The drill bit will be made of tough metals such as tungsten, and as the drill is rotated, the bit acts to grind up the rock. The broken pieces (cuttings) are flushed upward and out of the hole by circulating a drilling fluid (sometime called drilling mud) down through the drill pipe and back to the surface.
This drilling fluid also serves to cool and lubricate the drill bit, and by stabilizing the wall of the hole, it can prevent possible cavein of unstable sands or crumbly rock before the well casing or well screen is installed. As the drill intersects water bearing rock formations water will flow into the hole. Most drillers carefully monitor the depth of water "strikes" and keep a note of the formations in which they occur.
2. Air Hammer:
3. Cable Tool Method:
See also: Video of Cable Tool Method
Another drilling technique uses a "pounder" machine, usually referred to as cable tool drilling. With this method, a heavy bit is attached to the end of a wire cable and is raised and dropped repeatedly, pounding its way downward. Periodically, cuttings are bailed out of the hole. The method is slow and in most places has been replaced by rotary drilling. However the cable tool method is responsible for millions of successful wells around the world.
Considerations \ Precautions in drilling wells