Plugging-back of wells

Sanitary plugging-back is made with renewal of the initial protection of the horizon, according to the approved project.

The general plan of plugging-back includes preparation of the site around the well, delivery of the necessary equipment and materials, assembly of the equipment, inspection of the state of well (running the tubes for measurements to the bottomhole with simultaneous disposal of cuttings by flushing, identification of the state of casings), plugging-back with the help of coarse sand or graded fine gravel of the bottom part of well to the level of confining layer of the lowermost aquiferous horizon, opened up in the course of well drilling. It is needed for conservation and renewal of natural flow of underground water in aquiferous horizon.

In order to disinfect the well, the sand or gravel is pumped into it with the help of solution of chlorinated lime.

The plugging-back procedure also includes: cutting out and lifting (if possible) of the part of pipe string, which does not contact the rocks; filling the residual part of the wellbore with clay balls with the interval plugging-back, or cement grouting with addition of fine sand or other grouting mortar to the height that is by 1,25 m lower than the level of the day surface; cutting out of casings at the bottom of bore pit; filling the bore pit with the layer of concrete with thickness 0,25 m; filling the bore pit with local soil.

The unused wells with unknown design, partly filled with various objects, are eliminated after thorough works on the wellhead, running the caliper and impression blocks.