| abstract |
A method of treating an earth formation, especially a calcareous earth formation, containing petroleum and connate brine to stimulate production of the petroleum without substantially increasing the production of brine. A liquid pre-flush composition, including a water solution of polar solvent having dissolved in the solution rosin soap and fatty acid soap is injected into the formation. The preflush composition reacts with the connate brine to produce a precipitate that blocks the brinebearing passages, but the preflush composition does not react with the petroleum to produce a precipitate. Thus, the petroleum bearing passages are left open. Thereafter, an acid solution or other treating solution is injected into the formation to selectively stimulate or treat the oil-bearing passages. Preflush concentrates and compositions for use in the formation-treating method are disclosed as well as processes of making such compositions. |