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.

Abstract: The invention concerns a new process for plugging and/or consolidating a permeable geological formation, notably when traversed by a borehole.The process, according to this invention, comprises the following steps: (a) insertion into the formation of an overdelayed gelling compound, composed of a gelable material and a hardener, for which the setting time is considerably longer than the suitable positioning time for the composition, in such a way that this permeates the formation over a significant distance. (b) insertion, after a mechanical or fluid plug, of a rapid-action gelling agent, which causes the instantaneous gelling of that part of the overdelayed gelling compound in the immediate neighborhood of the interface between the zone to be treated and the borehole. Thus preventing displacement of the overdelayed gelling compound toward the interior of the formation. The resultant gelling being both resistant and correctly placed.The invention application is to oil, gas, water or geothermal drillings.