1. Construction principle of water well drilling tools: Drilling a pilot hole is to use directional drilling equipment to start directional drilling at the entrance. During the drilling process, the drill hole is extended according to the design trajectory through monitoring and control means. And drill out the surface from the other end to complete the construction of the pilot hole. If the pipeline to be installed is large and the reaming and back towing operations cannot be completed at the same time, the reaming is carried out step by step, and the diameter of each reaming is determined according to the equipment capacity, formation conditions and site conditions. Generally, pull back and reaming can be used. Pipeline pullback means that the directional drilling rig connects the pipeline to the drill pipe through the pullback head, the reaming bit and the transfer case at the exit, and uses the drilling equipment to rotate and pull back at the same time. bit, the reaming and dragging process is carried out continuously. There should be no long non-work pauses in between.

　　2. The directional drilling rig technology is an advanced technology developed from the field of oil drilling. It uses technical means such as rock drilling and directional drilling rig measurement and control. In the case of no trenching on the surface and minimal damage to the stratum structure, such as water supply, gas, Construction technology for laying public pipelines such as natural gas, sewage, and telecommunication cables. Directional drilling rigs have a wide range of applications. They can use bottom-hole motors or rigid drill rods to drive the drill bit to rotate to drill into holes, and can also be used for construction in hard rock or pebble layers.

　　3. Matters needing attention: First, according to the geological conditions of the crossing, select the appropriate drill bit and guide plate or underground mud motor, and start the mud pump to drill at the entry point. The drilling rig drives the rotation to cut the stratum and moves forward continuously. After each drilling, the position should be measured to adjust the drilling direction of the drill bit in time to ensure that the completed drilling guide curve meets the design requirements. Repeat the operation until the drilling is completed. The problem of affecting the working efficiency of the machine due to the position deviation of the drill bit can be avoided. Under normal circumstances, when using a small drilling rig, when the straight diameter is greater than 200 mm, pre-reaming is required. When using a drilling rig, when the diameter of the product pipeline is greater than 350 mm, pre-reaming is required. The scope and number of pre-reaming, It depends on the rig model and geological conditions. The use of horizontal directional drilling in this way not only reduces the resistance, but also protects the anti-corrosion layer of the pipeline. The construction cost is saved, and the working efficiency of the machine is improved.