Abstract: A scale removal agent may effectively be introduced into a well having a formation temperature of 300° F. The scale removal agent is a component of a gelled fluid containing an amine oxide viscoelastic surfactant.

Abstract: A composite for controlling the release of a well treatment agent or for inhibiting or preventing the formation of contaminants into a fluid or a surface within a reservoir contains a well treatment agent immobilized on a surface of the support or into the pores of a porous support. The composite is at least partially coated with an organic polymer or inorganic material. The composite exhibits sufficient strength for the composite to be used as a proppant or in conjunction with a proppant.

Abstract: A composition of a mixture of at least three organic acids with hydrofluoric acid (HF) generates a system that stimulates subterranean sandstone formations, enhances the permeability thereof, and therefore increases the formation's productivity. This system has a very low corrosion rate and may start with a pH greater than about 2. It is suitable for high temperature wells (greater than about 250° F. (121° C.)) and wells completed with specialized metal alloys. The system is hydrochloric acid-free and is compatible with high clay formations. Particularly suitable organic acids include, but are not necessarily limited to, the dicarboxylic acids succinic acid, glutaric acid, adipic acid, and mixtures thereof. Alternatively, the hydrofluoric acid is supplied by a substance that hydrolyzes to HF (e.g. ammonium bifluoride) and boric acid is included to delay the hydrolyzing to HF.