Abstract: The invention relates to iron control in an acid medium for forestalling the formation of precipitates known as “sludges” (asphaltic products) in contact with certain crude oils. Use is made of compounds comprising a mercaptan function, and, in combination, a selection of catalysts. Application to acid treatments for oil, gas, water, geothermal and analogous wells, as well as to industrial cleaning.

Abstract: In the presence of certain crude oils, when ferric iron exists in very acidic fluid, it practically instantaneously forms precipitates known as sludges which lead to irreversible damage. Iron control compositions and acid fluids containing such iron control compositions are disclosed. For acid fluids containing up to 15% acid, the iron control composition includes a reducing agent selected from a substituted and unsubstituted thiourea compounds, and a reduction catalyst including a copper (cuprous or cupric) compound. When the acid fluid contains more than 15% acid, for example from 15 to 28% acid, the reducing agent is again selected from substituted or unsubstituted thiourea compounds, and the reduction catalyst is a combination of a copper (cuprous or cupric) compound and iodine (iodine or iodide ions).

Abstract: The invention relates to iron control in an acid medium for forestalling the formation of precipitates known as "sludges" (asphaltic products) in contact with certain crude oils.Use is made of compounds comprising a mercaptan function non miscible in water and, in combination, a selection of catalysts.Application to acid treatments for oil, gas, water, geothermal and analogous wells, as well as to industrial cleaning.