| abstract |
Subterranean formations containing iron deposits are treated, for example to stimulate them, using as an iron sequestrant at least one of hydroxylamine hydrochloride, hydroxylamine hydrobromide, hydroxylamine sulfate, hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine sulfate, hydrazine monobromide, hydrazine dibromide, hydrazine monoiodide, hydrazine diiodide and hydroquinone together with a catalytic amount of a solubilized salt of a compound capable of providing cupric, cuprous, nickel, zinc ions or mixtures thereof. Preferably, there is also used at least one of gluconodeltalactone, citric acid, salts of citric acid, ethylenediaminetetraacetic acid, salts or ethylenediaminetetraacetic acid, nitrilotriacetic acid, salts of nitrilotriacetic acid, hydroxyethylethylenediaminetrieactic acid, and salts of hydroxyethylethylenediaminetriacetic acid. |