METHOD FOR CLEANING AND TREATING BOTTOMHOLE ZONE OF HORIZONTAL WELL IN BITUMEN DEPOSIT Russian patent published in 2017 - IPC E21B43/25 E21B37/00 

FIELD: oil and gas industry.

SUBSTANCE: method for cleaning and treating the bottomhole zone of the horizontal well in bitumen deposit includes lowering a coiled tubing string into the well and fixation of the descent depth, pumping of aerated flushing fluid through the coiled tubing string, cleaning of bottomhole zone from colmatage sediments by flushing, transporting and circulating thereof into chute container. At that, lowering of the coiled tubing string equipped with pear-shaped packing at the end is carried out into the well down to the depth of 50 m below the well head. A nitrogen compressor is started in the line of the coiled tubing string and aeration of the flushing fluid is carried out, with simultaneous relowering of the coiled tubing string to down to the depth of the initial part of the shank filter. After that pump unit is started with supply of flushing fluid to the line of the coiled tubing string. Then bottomhole zone is cleaned in four cycles by flushing with aerated fluid. Each cycle consists of moving the coiled tubing string at a rate of 1 m/s to the face with simultaneous flushing with aerated fluid. After reaching the bottom, the movement of the coiled tubing string is stopped. The well is flushed with aerated fluid for 30 minutes. Then the pump unit and the nitrogen compressor are switched off. A 30 minutes process pause is held. At that, the level of liquid in the well is marked with echo sounder. Further, the coiled tubing string is raised to a depth of 50 m below the well head. After that the above-described cycle is repeated three times. Then bottomhole formation zone is treated by injection of 8% hydrochloric acid in interval of horizontal part of wellbore from beginning of filter part of the shankl to bottom by 0.2 m³ for every 50 m followed by forcing hydrochloric acid into fresh water formation.

EFFECT: improved cleaning quality of the horizontal well bottomhole zone and increased cleaning efficiency of well bottomhole zone.

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