IMPROVEMENT OF WELL FLUSHING TECHNOLOGY DURING DRILLING IN PERMAFROST

The article presents the research results on flushing of wells during drilling in permafrost. The most effective flushing method is the use of drill fluids added with various antifreeze agents. In order to reduce the time spent on the implementation of this method of well flushing, as well as to prevent thawing and collapse of rocks in unstable intervals of wells, before the addition of antifreeze agents, the drill fluid is cooled down to the desired temperature. To cool drill fluids in summer, a refrigeration machine is used. In winter period, natural cold accumulated by atmospheric air is used for cooling. The drill fluid is cooled by any known method, including simplified approaches without using of complex and energy-consuming compressor refrigeration machines, by air heat exchangers blown with cold air. The proposed method involves the negative temperature mode of flushing and can be used when drilling wells of any purpose, diameter and length in permafrost up to 600m thick.