Energy-gathered bundle type nesting plugging and wall reinforcing device and application thereof in karst cave plugging

An application of an energy-gathered bundle type nesting plugging and wall reinforcing device in karst cave plugging, comprising the steps of:

• 1) if an external slotted metal pipe is single-layered, requiring a length of the metal pipe to be 400 mm longer than a longitudinal length of a karst cave;
• if the external slotted metal pipe is double-layered, selecting two metal pipes of different sizes, a wall thickness of each of the metal pipes varying with different metal materials;
• an inner diameter of an outer layered metal pipe is equal to an outer diameter of an inner layered metal pipe, an outer diameter of the outer layered metal pipe is 5 mm to 10 mm smaller than a diameter of a drill bit for drilling a plugged well section, and the two metal pipes have a same length that is 400 mm longer than a longitudinal length of the karst cave;
• 2) for the single-layered slotted metal pipe, cutting a plurality of straight slits or spiral slits on a pipe wall of the metal pipe on the ground, and leaving an upper end and a lower end of the metal pipe for 30 mm to 200 mm without cutting, thereby obtaining the single-layered slotted metal pipe;
• for the double-layered slotted metal pipe, cutting spiral strips with different left and right turning directions on two metal pipes on the ground respectively, widths of the spiral strips being 10 mm to 50 mm;
• leaving an upper end and a lower end of each of the two metal pipes for 30 mm to 200 mm without cutting, thereby obtaining the double-layered slotted metal pipe;
• or, cutting a plurality of straight slits on a pipe wall of each of the two metal pipes, a straight slit spacing on the inner layered metal pipe is different from a straight slit spacing on the outer layered metal pipe;
• also, leaving an upper end and a lower end of each of the two metal pipes for 30 mm to 200 mm without cutting, thereby obtaining the double-layered slotted metal pipe;
• 3) connecting a mandrel having a plurality of explosive grooves below a downhole drilling tool, widths of the explosive grooves varying with amounts of explosives placed;
• if the straight slits are cut on the metal pipe, the explosive grooves of the mandrel are spiral grooves, and if the spiral slits are cut on the metal pipe, the explosive grooves of the mandrel are straight grooves;
• next, sleeving the mandrel with the slotted metal pipe and fixing the slotted metal pipe, with a movable fit therebetween, and placing explosives in the explosive grooves of the mandrel;
• 4) delivering the mandrel to the karst cave using the drilling tool to ignite the explosives;
• by using energy generated by an explosion of the explosives, causing the slotted metal pipe fixed on the mandrel to be plastically deformed and attached to a wall of the karst cave, the upper end and the lower end of the slotted metal pipe respectively abutting against an upper plate and a lower plate of the karst cave to complete a nesting operation;
• next, injecting a long fiber material or a plugging glue to form an artificial well wall, thereby ensuring that the drilling can pass through a plurality of meters of karst cave safely, efficiently and quickly.