In naturally developed wells, fine formation material around the screen is removed by a developing process to create a more permeable zone. Certain conditions, however, favor the construction of an artificial gravel pack or the addition of a formation stabilizer.
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The objective of well development is the removal of fine sand, silt, and other such materials from the zone immediately surrounding the well to increase the permeabilty of the zone. Another purpose is to correct any clogging or compacting of the formation resulting from drilling operations. Development also grades the aquifer material around the screen to achieve maximum yields of sand free water.
There are several well-development methods in use, but three of the most effective and commonly used are mechanical surging, high-velocity jetting, and backwashing.
When the aquifer contains many clay streaks or clay balls,
the action of the plunger can cause the clay to smear over the
screen surface and reduce the yield. Also, the surging caused
by the plunger can cause high differential pressures in the well
which could collapse the screen, unless a sufficiently free flow
of water has been established in the well before surging is begun.
Care should be taken if the overlying formation is soft clay, fine
sand, or silt.
The jet washes fine materials out of the water-bearing formation and the turbulence created by the jet washes the material into the well. When possible, lightly pump the well during jetting operations.
Some wells respond to this, but the surging action is not vigorous enough to obtain maximum results in most cases.
A string of pipe let down in the well to about its full depth is connected to the discharge of the pump. Water is then pumped from the well and circulated back into the inside the screened section. The turbulence thus created inside the well screen assists in developing the well.
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