Sand production and building of borehole storage facilities in Russia’s Far North

Abstract

The environmental problems that arise in the course of gas–condensate and oil field development in the conditions of the Russian Far North are discussed. It is urgent to boost theoretical advancement in the area of design as well as structural and process decision-making when justifying parameters for building underground storage facilities for liquid and solid waste of drilling. Building of borehole storage facilities belongs in the class of physicochemical geotechnologies, which supposes that a part of natural rock mass is removed via a borehole drilled from ground surface (borehole hydraulic technology). The main processes involved in the building are thermal destruction of permafrost sandy and clay rocks and the lift of sand and return water from bottomhole to ground surface. The lifting parameters should ensure removal of sand and water from boreholes at the preset flow rate and at the controlled water–air interface position in compliance with the underground storage facility building program. It is found that the average washout capacity in permafrost sandy rocks during construction of an underground storage facility is linearly dependent on the product of average reduced rate of thermal destruction and average temperature of water in borehole, which proves the accepted washout design procedure. In the zone of a future underground storage facility in permafrost sandy rocks, it is typical that rock properties are highly variable both along and across sand strata. The air-lift parameters depend on the air-lift capacity and on the density of fluid to be lifted. The stable air-lift of sandy slurry is possible when the slurry density is not higher than 1.4 g/cm3, which conforms to the water content round 54 %.