Abstract: In-depth formation damage is prevented during water injection by adding to the water non-compressible solids of sufficient size and concentration to form an external filter cake within the injection well. Preferably, the non-compressible solids are either diatomite, perlite, saw dust, or calcium carbonate, and the concentration of non-compressible solids is from 0.001 to 5 wt%. When no longer needed, the external filter cake is removed from the injection well by using an acid wash or back-flowing the well.

Abstract: A method for reducing the amount of liquids produced from a selected geologic formation of a gas producing well is disclosed. A solution comprising controlled quantities of a scaling cation brine and scaling anion brine such that a scale will precipitate, and a controlled quantity of a scale inhibitor such that the scale precipitation will be delayed, is injected into the formation. The well is then shut-in long enough to allow the injected mixture to precipitate scale and to reduce the permeability of the formation such that a substantial portion of liquids that had been produced before, no longer are produced upon a resumption of gas production.

Abstract: A method is disclosed for prolonging the useful life of polymeric scale inhibitors or blends of non-polymeric and polymeric scale inhibitors injected within a formation. This method involves injecting an aqueous solution of polyquaternary amines into the formation. This solution of polyquaternary amines can be injected prior to, simultaneously with, or after the injection of the scale inhibitors. The scale inhibitors are preferably a blend of non-polymeric and polymeric scale inhibitors. Preferably, the polyquaternary amine is a poly-(dimethylamine-co-epichlorohydrin) or a poly-(diallyldimethylammonium chloride).

Abstract: A method is disclosed for prolonging the useful life of scale inhibitors injected within a formation. This method involves injecting aqueous solution of polyquaternary amines into the formation. This solution of polyquaternary amines can be injected either prior to or simultaneously with the injection of the scale inhibitors. The scale inhibitors are preferably non-polymeric scale inhibitors. Preferably, the polyquaternary amine is a poly(dimethylamine-co-epichlorohydrin) or a poly(diallyldimethylammonium chloride).