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Jetting - general

171 bytes added, 02:56, 17 July 2012

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[[Image:Jetting icon.png|right]]

[[Image:Manually rotated jetting.jpg|thumb|right|250px|Manually rotated jetting]]

Suitable for weakly cohesive sands and silts. Manual jetting is generally used up to depths of 35 meters.

 {{procontable | proborder="1" cellpadding="5" cellspacing="0" align="center"|-! width="50%" style="background:#efefef;" | Advantages! style="background:#ffdead;" | Disadvantages|-| valign="top" | - Very quick in fine and medium sand formations.<br>|convalign= "top" | - Generally limited to sandy soils. Soft clay will be penetrated only very slowly and coarse gravel and other highly permeable materials (cracks in the formation) cause loss of working water and cannot be drilled. The borehole stays open by water pressure. To prevent collapsing fluid-drilled boreholes must be kept full of water during the entire drilling and well installation process.<br>

- A large amount of working water needs to be available on the drilling location (several 200 liter drums/hour). The drilling and well installation needs to be done on the same day. Leaving the borehole open during the night has a high risk of collapsing.<br>

- The use of large quantities of water, the use of drilling fluids to greater depths and a motor pump make the equipment cost relatively high. <br>|}} 

==Construction, operations and maintenance==

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