METHOD FOR THERMO-CHEMICAL WELL BORE ZONE CLEANING Russian patent published in 2006 - IPC E21B43/27 

FIELD: oil production industry, particularly to remove mudding formations, namely argillaceous drilling fluid deposits and paraffin-hydrate sediments from well bore zone.

SUBSTANCE: method involves flushing well with aqua-based killing liquid; performing thermo-chemical well bore zone by concentrated sulfuric acid solution to which complexion agent is added; installing production string bottom at depth corresponding to water volume in well bore calculated from analytic formula; forcing mixture including concentrated sulfuric acid solution and complexion agent into production string. Displacement liquid is sulfuric acid-inert petroleum solvent. When concentrated sulfuric acid solution passes from production string bottom the injection is performed in pulsed mode. When necessary well bore volume is filled with mixture of concentrated sulfuric acid and complexion agent hole annuity is closed and the mixture in fed into well bore zone of productive bed in pulsed mode. Then the string space is closed and the well is left as it is for 4-6 hours to provide reaction inside it. Then production string is installed at gas-lift operation depth and solutions having opposite pH values are independently injected into the hole annuity. Flow rates are chosen to provide simultaneous solutions supply into string space. After that the string space is opened and reaction products are discharged into vessel.

EFFECT: improved efficiency due to increased fullness of mudding formation removal from well bore zone, enhanced production well output and improved injection ability.

6 cl, 1 tbl, 1 ex, 2 dwg