Abstract: Process for the consolidation of sand in a well which produces fluids, particularly oil and/or gas, comprising the following steps:1) optional preflush with an aqueous solution of inorganic salts, preferably KCl;2) injection into the formation of a consolidating agent essentially consisting of an aqueous solution of sodium silicate in water;3) flushing with an inert gas, preferably nitrogen, of the formation treated in step (2) until the excess consolidating agent and water injected in step (2) have been removed;4) subsequent introduction into the formation thus treated of an aqueous solution of an acid having a pKa at 25.degree. C. of between 3 and 10, preferably selected from ammonium chloride and acetic acid.