If the site is virgin and does not have any history of it than the site is first marked on the 1:50,000 scale topographic sheet. The physical terrain of the site is first verified and if the need be the site is visited before conducting the survey. The resistivity survey is based on the basic principle that every individual matter has got its own resistance (electrical) and the nature of the matter can be interpreted based on this conductance or resistance. In order to eliminate the failure rates, potential sites are pinpointed with the help of Geophysical equipment that can investigate and infer the type of formations to a depth of 1500 ft. depth and the interpretation is done using latest computer software like the one developed for Schlumberger array or any other alternate kind of electrode separation suitable based on the terrain. The interpretation of the data from the survey gives a fair idea of the formations below and the quantity of water that can be tapped.
Deputation of Rig: Based on the formations as depicted in the survey the type of rig which is to be deputed is decided. There are mainly the following types of drilling methods
| Reverse Circulation drilling |
| Direct Circulation drilling |
| Cable tool drilling or Percussion type of drilling |
| DTH (Down the Hole ) Drilling |
| Ordex |
The other kind of drilling methods are either adopted version of these above mentioned methods or are improvised
combination of these kinds of drilling like dual rotary method (Combination of DTH & Casing drilling), Combination Rig ( Direct rotary rig combined with Percussion drilling) etc.
