Wells for domestic purposes which require small quantity of water are bored with auger turned by hand.
Smaller wells in unconsolidated formations may be constructed by cutting action of a jet of water.
None of these two methods is however applicable to deep tube wells.
Deep and high yield wells are constructed by drilling.
There are various techniques of boring the well hole. All the techniques have their own merits and demerits, depending upon the formation in which drilling is to be done.
Most commonly used drilling methods have been described as follows.
1. Cable tools method or percussion drilling method.
2. Hydraulic rotary method.
3. Reverse rotary or jetting method.
1. Cable Tool Method or Percussion Drilling Method.
This method of drilling of the well hole is based on the use of striking force, (hammering and cutting) of the drilling bit, attached to the lower end of the cable.
The drilling bit is alternately lifted and dropped in the hole to break the formation.
In this method a standard well drilling rig consisting of a mast, a multiline hoist, a walking beam, and an engine are all mounted on a truck in assembled form so that equipment may be easily transported.
A string of cable tools, consists of a rope socket, a set of jars, a drill stem and a drill bit. A set of jars is used to aid in loosening tools struck in a hole and drill stem is used to provide length and weight to the cable tools.
The whole assembly of cable tools may weight 100 kg to over 2000 kg.
Percussion drilling tools.
A pit is dug at the site where well is to be bored.
A casing pipe along with drive shoe is erected vertically
Launch your Graphy