Hydrocarbon solvents such as xylene, toluene, and alcohols are being used with acid and sometimes instead of acid to treat some types of formation damage. In addition to the familiar roles of removing paraffin and tar, the solvents can be used successfully to remove oil-based mud damage, sludges, oil wetting problems and many emulsions. The solvents may also be used as preflushes for acids or mixed in with acids to enhance acid reaction. The success of solvent use depends upon the selection of the correct solvent and the best conditions for its application. The advantages of solvent usage are reduction or elimination of the acid and its accompanying corrosion and precipitation problems.

This paper deals with selection of the type and amount of solvent and the method of application. The actions of the solvents with various emulsions and sludges are discussed and suggestions are given for optimum reaction times. The guidelines were developed in the laboratory and have been field tested with excellent results. Laboratory and field results are given.

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