FIELD: mining, particularly to develop underground mineral deposit, for instance potassium salt deposit.
SUBSTANCE: method involves creating water-tight and fracture-closing screen in water-impervious rock layer, wherein the screen is formed as a number of cavities filled with viscous material; excavating mineral under the protection of water-impervious rock layer. The material used for cavity filling is flowable at working temperature, non-aggressive to water-impervious rock and adapted to isolate fractures. The material has density of not less than that of solutions, which tend to penetrate the screen cavities from overlayer flooded rock. The screen is coaxial to expendable or key well, which previously has been removed from operation. The well is drilled from land surface. The screen is created as horizontal cavity and vertical cavity communicated with horizontal cavity and filled with fracture-isolation material. The horizontal cavity is below lower boundary of water-impervious rock and spaced a distance H equal to or more than permissible water-impervious rock thickness from the boundary so that water-impervious rock is prevented from fracture formation during underworking thereof. The horizontal cavity radius is determined from mathematical expression. The vertical cavity extends along the well from horizontal cavity to at least upper boundary of water-impervious rock and has transversal dimensions equal to well diameter or exceeding thereof. Water-tight screen is formed after above well backfilling within the boundaries of water-impervious rock layer downwards from lower level of horizontal screen cavity. During screen usage cavity filling is controlled and fracture-isolation material is added into the cavities if necessary.
EFFECT: increased efficiency.
2 cl, 1 dwg
