METHOD OF CLEANING BOTTOM-HOLE FORMATION ZONE OF INJECTION WELLS AFTER HYDRAULIC FRACTURING Russian patent published in 2016 - IPC E21B37/00 

FIELD: oil industry.

SUBSTANCE: invention relates to oil industry, namely, to cleaning of bottom-hole zones of low-permeable formations in injection wells after formation hydraulic fracturing (FHF). After FHF TS with packer is lowered into well, well fluid is replaced for foam and packer is seated above formation, pumping in three cycles is made by pressing formation with water-gas mixture - foam. Pressure of foam injection into formation is increased in steps with each cycle of pressing up to value not higher than FHF pressure in last pressing cycle. Each pressing cycle consists of three process operations, involving pumping of foam into formation via TS to pressure, corresponding to each cycle with subsequent discharge of pressure through TS with opening valve at wellhead equipment and pouring of waste foam through union. Union diameter is decreased with increase of pressure in each cycle of foam pressing on formation, wherein at each technological operation drop of injection pressure is performed in stepwise manner with even pitch to atmospheric pressure in last process operation. After every cycle of pressing packer releasing, union replacement for larger diameter and reverse washing of well are made, then packer is installed for next cycle.

EFFECT: cleaning efficiency is increased, losses of intake capacity of low-permeable beds are decreased, method performances are expended irrespective of availability of surrounding production wells.

1 cl, 3 dwg