Abstract: A method is disclosed for transporting ball sealers down a perforated casing of a well to affect fluid diversion when hydraulically treating a formation penetrated by the well. In this invention, ball sealers are transported to said perforations in a carrier fluid system comprising a leading fluid portion having a density greater than said ball sealers and a trailing fluid portion having a density less than said ball sealers. The ball sealers will be moved downwardly in the casing to the perforations and will seat onto the perforations through which fluids are flowing to divert fluid through the unplugged perforations.

Abstract: A method of preventing the failure of a sand consolidation treatment due to contamination of the resinous material with aqueous rathole fluids during injection is described. The method involves displacing the aqueous rathole fluids with a dense, nonaqueous liquid prior to introducing the resinous material into the formation.

Abstract: A method is disclosed for generating or forming hydrofluoric acid in a subterranean siliceous formation by combining an injected aqueous solution of a fluoride salt and an injected aqueous acid solution in the pore spaces of the formation. This is accomplished according to this invention by immobilizing one of the aqueous solutions in the pore spaces of the formation by displacing the aqueous solution into the formation with a liquid that is substantially immiscible with the injected aqueous solution, thereby driving said aqueous solution to a saturation at or below its residual saturation. The other aqueous solution is then injected into the formation.

Abstract: A method of consolidating incompetent subterranean formation surrounding a well wherein a liquid resin diluted with a two-part diluent is injected into the formation and is followed by an overflush liquid to extract the diluent but leave the resin on the sand grains. The two-part diluent comprises a first component miscible with the resin and a second component immiscible with the resin but miscible with the first component and the overflush liquid.