A Guide To Water Well Casing and Screen Selection   -   14

5.4  Conductor Casing

Many wells require, for construction and occasionally protective reasons, the installation of a surface or conductor casing. Such casings range from 20 to 50 feet in length although more may be required to reach an impervious stratum. Usually surface casings for gravel envelope wells are 6 to 12 inches larger in diameter than the upper casing and approximately four inches larger for non-gravel envelope wells. Wall thicknesses range from .1875 inch to .3750 inch depending upon depth and diameter. The annular space between the casings may be grouted as well as the annular space between the conductor casing and its borehole.

Surface casing prevents the direct infiltration of polluted surface waters between the casing and borehole and stabilized the upper formations, which are usually unconsolidated, during drilling, completion and use.

Above:
Cementing conductor casing-positve
placement capped casing method.

Back   |   R & D Home   |   Next