Water Well Drilling and Development Scenario
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Water Well Drilling and Development Scenario of Drilling Equipment in India
Though, irrigation wells. Are known to exit from ancient times, real impetus to water well drilling for irrigation came only after independence and particularly with the launching of the planned development programme.  Notable break through in water well drilling, however, came when two consecutive droughts, during 1966-67 and 1967-68 swept over the country and exposed the vulnerability and canal irrigation in times of crises. It was only thereafter concerted efforts were made to explore and develop the much dependable ground water resources of the Country. Keeping in view the knowledge and field experience acquired by the Author on the various types of drilling rigs and well constructions a narration of various drilling techniques, design and construction of tube wells has been discussed in this article so as to provide the basic ideas for the well construction in various Hydro geological formations including development scenario of drilling equipment in India.
Particular drilling method have become popular in certain parts of the Country because they are most effective in penetrating the local hydro geological formations thus reducing the cost of various operations. In water well drilling we may change the usual drilling procedure depending on the depth and diameter of the well, type of formation to be drilled etc. It is, therefore, obvious that no single method of drilling is good for all types of hydro geological formations. Successful drilling is, therefore, an art developed from the long experience and the application of good engineering practices by the drilling engineers and drillers engaged in water well construction.

METHODS OF DRILLING
The methods of drilling and water well construction are so numerous that only the basic principles and some of their genera1 applications can be described. The most commonly used methods for well drilling and construction are: * Digging
* Boring
* Driving
* Jetting
* Reverse Circulation Drilling
* Cable tool Drilling
* Conventional Mud
*
Rotary Drilling
* Down the hole drilling (DTH)

Detail drilling operation and procedures shall be followed in the subsequent articles with more information about well design and construction with economics.

DIRECT MUD   ROTARY DRILLING

Direct Rotary Mud Drilling method
is becoming the most effective and widely practical procedure of all available drilling systems and has been adopted by the water well industry as the conventional drilling system. In water well drilling, this method is mostly deployed for drilling in unconsolidated and semi-consolidated formations alluvial soil, sand stone etc. for small as well as large diameter bore holes of any required depth. In this method drill string is consist of Kelley drill pipe and bit. For better result to maintain verticality of hole stabilizer and drill colars are also used in drill string. Mud pump is used to inject drilling fluid through drill rod and bit to the bore hole. The drilling fluid carries the cuttings from the bore hole and also gives cooling effects to the bit as well as it makes a semi-prominent plastering on the wall of the bore hole. The hydrostatic pressure of the fluid prevents the collapse of the bore hole.  A rotary table arrangement with the rig gives a rotation to the bit through drill rod. Different 'types of bits are used to encounter different type of formation. This type of drilling is faster method then that of percussion drilling.