| abstract |
In one embodiment, a retarded acid system comprises an aqueous acid and a retarding surfactant. The aqueous acid may comprise from 5 wt. % to 25 wt. % of a strong acid, that is, an acid having a K a greater than or equal to 0.01. The aqueous acid may further comprise from 75 wt. % to 95 wt. % water. The retarding surfactant may have the general chemical formula R—(OC 2 H 4 ) X —OH where R is a hydrocarbon having from 11 to 15 carbon atoms and x is an integer from 6 to 10. The retarding surfactant may have a hydrophilic-lipophilic balance from 8 to 16. |