The most important task of exploratory core drilling is to ensure high yield and quality of core - source material for geological and engineering-geological sampling. Analysis of production data of a number of organizations engaged in drilling in permafrost rocks shows that when drilling with flushing the core yield is 60-70% for bedrock with moisture content of 2 - 5% and 20-30% in rocks with moisture content of 15% and more. In production conditions very often in order to increase the core yield one switches to “dry” drilling. However, the core quality deteriorates sharply. Partial or complete thawing of the core takes place with violation of its structural characteristicsю

Currently, hard rocks account for about 25-30% of the total volume of exploration core drilling. Drilling is carried out by shotgun drilling. By the end of the seven-year plan (1959-1965) about 50% of shot drilling will be replaced by fine-diamond drilling. Thus, the improvement of shot drilling technology still plays a major role in accelerating the exploration of mineral deposits. One of the ways to improve the technology of shot drilling is blowing out the bottom hole with compressed air instead of flushing with water. Air, as a flushing agent, is not able to keep the walls of the well from collapse, but this is not required in shot drilling in strong rocks, as a rule. Compressed air successfully fulfills the other requirements to the flushing agent.