Abstract: A composition for sealing porous subterranean formations comprises a mixture of a water-swellable clay and a water insoluble, water absorbent, water-swellable polymer, wherein the mixture is coated with a material that is resistant to penetration by water. The water penetration resistant material helps the delay the onset of swelling of the clay and polymer until it reaches the formations intended for sealing. Mixing the clay with the water-swellable polymer prior to coating assists in coating of the water-swellable polymer with the water penetration resistant material. The coated mixture can be suspended in an aqueous liquid, and then pumped into a subterranean cavity to seal porous formations therein.

Abstract: A composition for sealing porous subterranean formations comprises a mixture of a water-swellable clay and a water insoluble, water absorbent, water-swellable polymer, wherein the mixture is coated with a material that is resistant to penetration by water. The water penetration resistant material helps the delay the onset of swelling of the clay and polymer until it reaches the formations intended for sealing. Mixing the clay with the water-swellable polymer prior to coating assists in coating of the water-swellable polymer with the water penetration resistant material. The coated mixture can be suspended in an aqueous liquid, and then pumped into a subterranean cavity to seal porous formations therein.

Abstract: A grouting composition for sealing a borehole or other cavity contains 90-99.9% finely divided water swellable clay and 0.1-10% polyacrylate thinner having a molecular weight of about 5,000 to 95,000. The grouting composition is mixed with fresh water to provide a completely reswellable, unflocculated, easily placed, low permeability sealing composition. The thinner allows a very high concentration of water-swellable clay in the composition. A preferred grouting composition contains 98-99.9% sodium bentonite and 0.1-2% polyacrylate thinner of molecular weight of about 2,000 to 50,000. In use, 50lb. of the preferred grouting composition is mixed with 11-14 gallons of fresh water, to provide a grouting mixture which includes about 25-40% reswellable solids.

Abstract: A grouting composition for sealing a borehole or other cavity comprising 90-99.9% finely divided water swellable clay and 0.1-10% thinner. The grouting composition is mixed with fresh water to provide a completely reswellable, unflocculated, easily placed, low permeability sealing composition. The thinner allows a very high concentration of water-swellable clay in the composition. A preferred grouting composition comprises 98-99.9% sodium bentonite and 0.1-2% polyacrylate thinner. In use, 50 lb. of the preferred grouting composition is mixed with 11-14 gallons fresh water, to provide a grouting mixture which comprises about 30-35% reswellable solids.