METHOD OF CLEANING OF BOTTOM-HOLE FORMATION ZONE Russian patent published in 2002 - IPC

FIELD: oil producing industry, particularly, methods of cleaning of bottom-hole formation zone from colmatant and asphalt-resinous-paraffin accumulations. SUBSTANCE: method includes successive injection into bottom-hole formation zone of gas- evolving solution and aqueous solution of hydrochloric acid forming carbon dioxide as result of reaction; process holding for reaction and pressure drop at bottom hole. Gas-evolving solution is used in form of aqueous solution of neutral salt of carbonic acid. After process holding, pressure is built-up at bottom hole corresponding to supercritical state of carbon dioxide with subsequent pressure drop at bottom hole. EFFECT: higher efficiency of cleaning and safety in operation. 3 dwg