Development of retarded acid system
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.
1. A retarded acid system comprising:
an aqueous acid;
the aqueous acid comprising:
from 5 wt. % to 35 wt. % of one or more of HF, HClO 4 , HClO 3 , HCl, HBr, HI, HNO 3 , HO 2 C 2 O 2 H, H 2 SO 4 , and H 2 SO 3 ; and
from 65 wt. % to 95 wt. % water; and
a retarding surfactant;
the retarding surfactant having the chemical formula R—(OC 2 H 4 ) X —OH, where:
R is a hydrocarbon having from 11 to 15 carbon atoms;
x is an integer from 6 to 10; and
the retarding surfactant has a hydrophilic-lipophilic balance from greater than 10 to 16;
where the ratio of the weight of retarding surfactant in the retarded acid system to the weight of the aqueous acid in the retarded acid system is from 1:25 to 1:5.
2. The retarded acid system of claim 1 , where R is a hydrocarbon having 13 carbon atoms and x is 8.
3. The retarded acid system of claim 1 , where the retarded acid system is free of hydrophobic organic alcohols.