How far to cement

How far to cement

If we are to concede the premise that cementing is essential to make a safe well, it must then follow that we cement to a point below the zone of possible contamination, and, if possible, to a point below the lowest pumping level.

This means that at least the lower part of the cemented area is below water.

With this fact in mind you cannot make a satisfactory cementing operation by dumping cement grout into the annular opening.

The proper method is to pump the cement into the hole or annular space through a pipe which has been installed to the bottom of the cemented area.

Two possible procedures are available to a driller using the simple pump and tank:

A pipe of any size, normally not less than 3/4 inch, can be run down the annular space to the bottom of the area to be cemented. Cement can then be pumped into the annulus until it returns to the surface.

The alternate procedure is to install a cementing shoe on the bottom of the liner or surface pipe. This shoe will have a back pressure valve. A cementing tube, or pipe, is lowered inside the liner and attached to the cement shoe, usually by means of a right and left hand thread.

Cement can be pumped down through the tube and out into the annular space until the annular space is completely filled.

The tubing or pipe is unscrewed. The back pressure check valve will close. Surplus cement is then washed out of the tubing and it is removed from the well.

This alternate method is particularly necessary where the annular space is restricted and where a pipe cannot be installed down the annular opening.

Cementing is not a complicated procedure.

You can derive a great deal of satisfaction from the repetition of proven techniques of grouting which can add to the quality of your work.