METHOD FOR ACID TREATMENT OF BOTTOM-HOLE FORMATION ZONE Russian patent published in 1996 - IPC

FIELD: oil producing industry, particular, methods for acid treatment of bottom-hole formation zones. SUBSTANCE: method for acid treatment of bottom-hole formation zone includes successive injection into well of aqueous solution of nitrate or mixture of nitrates of the metals from the group including beryllium, bismuth, cadmium, cobalt, manganese, copper, nickel, lead, strontium, aluminium, iron, chromium, tin with the content of nitrates in aqueous solution from 2.0 mas.% up to that corresponding to saturated solution, and aqueous 1.0-36.0 mas.% solution of hydrochloric acid. Amounts of aqueous solution of nitrates and aqueous solution of hydrochloric acid are determined by mathematic expression. The method may be modified by addition of nonionic surfactants, mixture of nonionic surfactants into aqueous solution of nitrates in the amount of 0.001-5.0 vol.% by addition of anionic, cationic, nonionic surfactants or mixtures of these surfactants to aqueous solution of hydrochloric acid in the amount of 0.001-5.0 vol.% by addition of hydrochloric acid to aqueous solution of hydrochloric acid in the amount of 0.1-6.0 mas.% and also by addition of anionic, cationic, nonionic surfactants or mixtures of these surfactants to aqueous solution of mixture of hydrochloric and hydrofluoric acids in the amounts of 0.001-5.0 vol. %. Volume of aqueous solution of hydrofluoric acid for preparation of mixture of aqueous solutions of hydrochloric and hydrofluoric acids is determined by the mathematic expression. EFFECT: increased well production rate due to increased amount of dissolved reservoir rocks with preserved depth of treatment. 4 cl, 1 tbl