First of all, the first type of percussive water well drilling rig mainly relies on the vertical reciprocating motion of drilling tools to make the drill bit impact the bottom of the well to break the rock layer. Its structure is simple, there is no circulation washing system, and the removal of rock chips cannot be carried out simultaneously with the drilling rig, thus its efficacy is low. The drilling depth is generally within 250 meters, sometimes up to 500-600 meters. There are mainly 2 types:
① Flush grab cone. Using the weight of the drilling tool itself to impact the formation. When the drilling tool moves downward under its own weight, the flaps open and cut into the rock layer, and then the drilling tool is lifted by the winch through the wire rope, and the flaps are closed to grab the rock chips into the cone and unload the chips from the wellhead. The drilling depth is usually 40 to 50 meters, and the deepest depth is 100 to 150 meters.
② Wireline percussion drilling rig. It is composed of mast and lifting pulley mounted on the top, steel wire rope, impact mechanism, drilling tools, electric motor and so on. During operation, the electric motor drives the impact mechanism through the transmission device and drives the wire rope to make the drilling tool reciprocate up and down, relying on the weight of the drill bit itself to cut into and break the rock layer during the downward movement, and relying on the wire rope to pull it upward. The drill stroke is 0.5~1m, and the impact frequency is 30~60 times/minute. The rock chips are cleared out of the ground by the sand extraction cylinder, and drilling and chip removal are carried out simultaneously.
Next is the second type of rotary water well drilling rig, which mainly relies on the rotary motion of drilling tools to break the rock layer and make holes. There are mainly 5 types:
(1) Pot Cone. Using its pot cone drilling tool to rotate and cut the soil layer. According to the size of the drilling tool, it is called big pot cone and small pot cone respectively, which can be driven by human power or power. The cut soil chips fall into the pot and are lifted to the ground and unloaded. Its simple structure and low efficacy are suitable for general soil layer or sand and pebble soil layer. The drilling depth is 80-100 meters for small pot cone and 30-40 meters for large pot cone.
(2) Circulating mud washing rotary drilling rig. It is composed of tower, winch, turntable, drilling tools, mud pump, tap and electric motor. During operation, the power machine drives the turntable through the transmission device, and the active drill pipe drives the drill bit to rotate and break the rock formation. There are two types of circulation: positive and negative. When the positive circulation drilling rig is in operation, the rock chips at the bottom of the well are brought out of the wellhead through the annular channel outside the drill pipe, and after settling in the sedimentation tank, the mud flows back to the mud tank for recycling. When the reverse circulation drilling rig is working, the mud flows into the bottom of the well from the wellhead by itself after settling in the sedimentation tank, while the mud carrying rock chips is pumped out of the well by the gravel pump through the drill bit water outlet through the inner cavity of the drill pipe upwards and sinks back to the sedimentation tank. The drilling rig forms a high upward flow rate in the drill pipe, with a strong ability to discharge rock chips and pebbles, and a fast drilling speed, which is suitable for loose formations where the diameter of soil, sand and pebbles is smaller than the internal diameter of the drill pipe. The drilling depth is generally within 150 meters.
(3) Pressure gas washing rotary drilling rig. Air compressor is used on the rotary drilling rig instead of mud pump to wash the well with compressed air instead of mud. It usually adopts the reverse circulation method, also called air lift reverse circulation. It is suitable for arid areas with large well depth and water shortage and cold zone tundra.
(4) Hydraulic power head type drilling rig. It is driven by hydraulic motor through reducer, and the power head that moves up and down along the tower replaces the turntable and tap on the rotary drilling rig to drive the drill pipe and drill bit to rotate and cut the rock layer. It can drill large diameter water wells.
(5) Submerged vibratory rotary drilling rig. It drills rock formations by a combination of vibration and rotary motion. The drilling tool consists of drill bit, vibrator, vibration damper and guide barrel. The vibrating force generated by the vibrator makes the whole drilling tool make conical pendulum movement to break the rock formation. Compressed air is used to wash the well in reverse circulation, so that the rock chips are discharged through the conduit and the inner cavity of the drill pipe. The drilling depth can reach 150 meters.
The third type of composite water well drilling rig has 2 types:
One is the water well drilling rig that combines impact and rotary action in drilling, such as the wind-driven submersible hammer drilling rig. The submersible hammer drilling tools consist of cylinder sleeve and piston, etc. High-pressure air is provided by the air compressor to push the piston up and down in a reciprocating motion, impacting the drill bit to enhance the ability of the bit to drill into the rock formation. At the same time, the drilling tool makes a rotary motion at a lower speed of 35-60 rpm. The air discharged from the upper and lower cavities of the piston enters the drill bit and brings the rock chips out of the hole bottom. The wind-driven submersible hammer drilling rig can be used for drilling deep wells in hard rock formations, with high drilling speed and straighter drilled holes.
The other is a dual-purpose water well drilling rig with an impact mechanism added to the rotary drilling rig, which is mainly used for rotary drilling and percussion drilling when encountering pebble layers, and is highly adaptable to various strata.