INSTALLATION METHOD OF EASILY BREAKABLE CEMENT PLUG IN HORIZONTAL WELL Russian patent published in 2015 - IPC E21B33/134 C09K8/467 C09K8/14 

FIELD: oil and gas industry.

SUBSTANCE: installation method of easily breakable cement plug in horizontal well includes running in of the tubing string to a horizontal well up to interval of the plug setting, injecting of cement grout and chalk stone and flush fluid through the tubing string up to the plug setting interval, breaking of the plug with hydrochloric acid solution upon repair. Reduced-weight cement slurry with density of 1270-1410 kg/m³ is used as cement grout; it is based on sedimentation stable plugging material (SSPM) with the following ratio of ingredients, by weight fractions: SSPM 29.2-49.3, choke stone 9.8-23.4, water - the remaining share. Clay mud based on bentonite with density of 1130 kg/m is used as flush fluid; it is injected before and upon injection of reduced-weight cement slurry in volume not less than 25% of the volume of reduced-weight cement slurry, at that in order to break the plug of this slurry 12% inhibited hydrochloric acid is used, which is pumped into the horizontal well in volume of the tubing string, the process is withhold for the purpose of the plug breaking for 8 hours and thereupon reaction products are flushed from the horizontal well.

EFFECT: increased sealing at the plug setting in the horizontal well, increased strength of the set plug.

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