Single borehole multilateral directional butted well salt mining method

The invention discloses a single borehole multilateral directional butted well salt mining method, which comprises the steps of: firstly conducting boring to a predetermined depth K1, then performing deflection by a directional drilling technology, boring out an inclined shaft through W1 and K2 points and reaching a T point in the ore bed, laying a casing pipe A to form a well, and conducting dissolution in the ore bed to build a small cave; in the same borehole, using a smaller level boring tool to pass through the deflecting point K1, carrying out boring downward vertically to a predetermined deflecting point K3, performing deflecting boring into the ore bed, laying a casing pipe B in the section of small-caliber borehole for well cementation; in the casing pipe B, using a smaller level boring tool to conduct further deflecting, boring a horizontal well section in the ore bed to realize butt joint with the small cave built in the first step; laying a center pipe in the casing pipe B, carrying out sealing connection on the center pipe end and the casing pipe B with a packer, and mounting well head equipment. The method provided by the invention utilizes directional boring and multilateral well technologies to build the horizontal butted well channel meeting brine mining at a smallest boring project amount.