How does it work?
The procedure involves lowering down the well one or two inflatable hard rubber "sleeves" or "balloons"
(packers as they are more correctly called). First, all pipes, wires and the pump need to be removed from the well. The packers are then inflated to seal off a section of the well. The packers are usually set a minimum of 20 feet below the end of the casing and 60 feet below ground surface. Water is pumped at high pressure into the section of the well between the packers, or below the packer if only one is used. Most hydrofracturing equipment for private wells can provide between 500 and 2000 psi pressure, sometimes up to 3,000 psi (pounds per square inch). Up to 50 gallons a minute is usually adequate as a pumping rate for adding water into the well. Some states have specific regulations relating to the
The water pressure within the sealed-off section of the well will rise as the surrounding rocks resist the flow of water out of the well. A sign of successful hydrofracturing is a sudden drop in the pressure indicating that the surrounding rocks are accepting water. If more fissures have been opened there is often a strong backflow of turbid water when pumping into the well is stopped. If however, during the hydrofracturing process the pressure in the well increases to the maximum working pressure of the equipment, with no sudden drop in pressure, then the hydrofracturing procedure may not have been effective.
The cost for single packer hydrofracturing is usually less than when a double packer system is used. A double system allows for a selected zone in the well to pressured by inflating both packers. The packers are usually first set near the bottom of the well and then moved up to another section. Selection of the zones to pressurize may be made from information on the well drillers log or from a down-hole camera survey. Although not often used, some contractors may use proppants (small beads or sand grains) to keep open (prop) fractures & cracks in the rock.
There may be permit and reporting requirements for hydrofracturing. Well contractors who specialize in hydrofracturing services will know whether
"paperwork" is required.
Before & After Test
In order to assess the effectiveness of the hydrofracturing process the contractor will usually perform a "before & after" test of the well yield.
Influence on Neighboring Wells
There is the potential for the hydrofracturing process to temporarily influence water levels or turbidity in a close-by neighboring well if the two wells share some of the same fractures.
High Quality Water
The contractor should use high quality water (and/ or water pumped in advance from the well to be pressurized) for the hydrofracturing process to avoid introducing any contaminants into the aquifer.
After hydrofracturing, the contractor will normally purge the well of fine material but there could be some cloudiness in the water for a few days.
It is normal practice to sanitize a well after any maintenance or well
development work. You may have to wait 24 hours before the well can be put back into use.