О некоторых особенностях сооружения и эксплуатации технологических скважин в криолитозоне

Abstract

A feature of Russian mineral deposits is that about 75% of them are loca­ted in the permafrost zone. Uranium deposits located in the permafrost zone and mined by the method of borehole in-situ leaching make a significant contribution to the all-Russian production of this metal. Complex mining and geological conditions of uranium mining in the permafrost zone require the adoption of extraordinary technical approaches to solving the issues of developing such deposits. The quality of process wells construction for in-situ leaching of uranium and the preservation of their operational characteristics throughout the entire period of operation. The relevance of the work is associated with the need to ensure efficient and environmentally safe uranium mining by in-situ leaching in a cryolithozone. This paper discusses the design elements of process wells that affect their operational performance, the temperature loads acting on production strings made of polymeric materials (low-density polyethylene and unplasticized polyvinyl chloride), the seasonality of well construction, and their operating modes. The author does not consider polymer materials of other types: fiberglass (have high brittleness, roads, tested in the late 1980s in Uzbekistan), metal-plastic (absolutely unsuitable for operation due to metal corrosion in case of violation of the polymer coating, for example, during repair and restoration work, were tested in Uzbekistan and Kazakhstan in 1985–1988, including with the participation of the author), polypropylene and acryl butadiene styrene pipes (low physical and mechanical characteristics). The analysis has showed that the temperature effect on polymer casing pipes is one of the most important factors, taking into account which it is possible to ensure trouble-free operation of constructed process wells. The work includes the analysis and processing of actual materials obtained during the construction and operation of wells. The conclusions have made it possible to determine the most effective technologies for equipping polymer production strings of technological wells, to select equipment elements and materials for waterproofing the casing space.