Things to remember

Things to remember

Following are some more points about cementing:

1.) If your operation is limited to small wells (25 to 50 sacks of cement) you will probably be using small pumping equipment and a small cement tube.

This being the case, you must be very careful to provide exceptionally good screening ahead of the pump and use well mixed grout, free of all lumps and foreign material.

On larger pumps you can pass larger lumps and often can add to the mixture, loss circulating material such as seal flakes (shredded cellophane), Palco Seal (shredded redwood bark), etc.

These additives are very essential in establishing circulation in heavily creviced zones.

By being able to pump such material, you may be able to complete a cementing operation which a smaller pump would not have been able to handle.

2.) One advantage of pressure grouting is that you are not only cementing the annular space between a hole and a liner pipe, but you are also forcing grout back into cavities and crevices that contribute to possible contamination or bad corrosive water to the annular space.

When this is done, even though you may have some voids and possible shrinkage cracks in the cement envelope, the chances are that the liner is amply protected.

In the author's 30 years of experience with pressure grouted wells, I have never found a leaky casing where the casing was pressure-grouted in place.

3.) In handling cement grout you must plan on "pacing" the cement and must finish all pumping of same within approximately four hours.

The initial set of regular Portland cement takes place in about this time.

If the time is more than this elapsed time, you will encounter increased resistance to pumping.

So plan your work accordingly.