Water Well Drilling Rig used for drilling wells and completing operations such as running pipes and washing wells. Including power equipment and drill bit, drill pipe, core pipe, drill frame, etc. Generally, it can be divided into three categories: rotary rotary drilling machine, percussive drilling machine and compound rotary machine.
The hole is formed by breaking the rock stratum by rotary movement of drilling tool. There are mainly large and small pan cone drilling rig, positive and reverse circulation rotary drilling rig, hydraulic power head drilling rig, DTH vibration rotary drilling rig, etc. Simple rotary drilling rig only has drilling device, while rotary drilling rig with perfect structure consists of drilling device and circulating well washing device. The drilling tools of rotary drilling rig include drill pipe and bit. There are four kinds of nominal diameter of drill pipe in common use: 60 mm, 73 mm, 89 mm and 114 mm. The drill bit is divided into two categories: the overall drilling bit and the annular drilling bit. The large and small pot cones use their cone drilling tools to cut the soil layer.
According to the size of the drilling tool, they are called big pot cone and small pot cone, which can be driven by manpower or power. The cut soil chips fall into the pot and are lifted to the ground for unloading. The structure is simple and the work efficiency is low. It can only be used in the general soil layer or the stratum with sand gravel diameter less than 10 cm and content less than 50%. The hole diameter of the small pot cone is 0.55 m, and the drilling depth is 80-100 m; the diameter of the large pot cone is 1.1 m, and the drilling depth is 30-40 M.
Rotary drilling rig commonly used in rotary drilling rig with positive and reverse circulation mud (Fig. 1) is composed of tower, winch, rotary table, drilling tool, mud pump, tap and motor. During operation, the power machine drives the rotary table through the transmission device, and the drill bit is driven by the driving drill pipe to rotate and crush the rock stratum at the speed of 30-90 rpm. After being pumped and pressurized by the mud pump, the mud is pressed into the hollow drill pipe through the tap above the drill pipe, and flows downward into the drill bit, and is ejected from the nozzle to cool and lubricate the bit; the bottom hole cuttings are taken out of the wellhead through the annular channel outside the drill pipe, and the mud flows back to the mud pool for recycling after sedimentation in the sedimentation tank.
The drilling method and structure of the reverse circulation mud washing rotary drilling rig are basically the same as the above, but the circulation mode of the mud is opposite: the mud flows into the bottom of the well from the wellhead after settling in the sedimentation tank, and the mud carrying cuttings is pumped out of the well through the inner cavity of the drill pipe by the sand pump through the bit nozzle and returns to the sedimentation tank. This method is called pump suction reverse circulation. Water pump can also be used to inject pressurized water from the bottom of the well through the nozzle into the inner cavity of the drill pipe to form upward flow carrying cuttings, which is called jet reverse circulation. The drilling rig can form a high ascending velocity in the drill pipe, and has a strong ability to discharge cuttings and pebbles, so the drilling speed is fast. It is suitable for soil layer, general sand layer and loose stratum where the diameter of pebble is smaller than the inner diameter of drill pipe.
The inner diameter of drill pipe used is larger, generally 150-200 mm, and the maximum is 300 mm. However, due to the limitation of pump suction or pressure delivery capacity, the drilling depth is generally less than 150 meters, and the chip removal efficiency is higher when the well depth is less than 50 meters. Air compressor is used to replace mud pump and compressed air is used to replace mud pump. Reverse circulation is usually used, also known as gas lift reverse circulation (Fig. 2).
The compressed air is sent to the air water mixing chamber through the air supply pipeline to mix with the water flow in the drill pipe to form aerated water flow with specific gravity less than 1. Under the gravity of the annular water column around the drill pipe, the aerated water carrying cuttings in the drill pipe rises continuously and is discharged out of the well to flow into the sedimentation tank, and the settled water flows back to the well by gravity. When the well depth is larger (more than 50m), the chip removal capacity of this kind of drilling rig is greater than that of the drilling machine with pump suction or jet reverse circulation. Therefore, this kind of drilling rig is suitable for the situation of larger well depth, drought area with water shortage and frozen soil layer in cold zone.
Some rotary drilling rigs are equipped with mud pump and air compressor at the same time, so different washing methods can be selected according to the situation.
A kind of rotary drilling rig with hydraulic power head. Driven by a hydraulic motor through a reducer, the power head moving up and down along the tower replaces the rotary table and faucet on the rotary drilling rig to drive the drill pipe and drill bit to rotate and cut the rock stratum. Large diameter water wells can be drilled with a large drill bit with a diameter of 1 m. its features are fast drilling speed, easy loading and unloading of drilling tools and easy running of well casing. When the drill pipe is extended, it is unnecessary to lift the drilling tool, and a series of components such as winch, lifting pulley, rotary table, faucet and square drill pipe are avoided. Down the hole vibration rotary drilling rig is a kind of rotary drilling rig which combines vibration and rotary motion to drill rock strata. The drilling tool is composed of bit, vibrator, vibration absorber and guide tube (Fig. 3). The exciting force produced by the vibrator makes the whole drilling tool swing. The drill bit is set on the outside of the vibrator shell through friction ring. On the one hand, it vibrates with the vibrator's working frequency of about 1000 rpm and amplitude of about 9 mm; on the other hand, it rotates at a low speed of 3-12 RPM around the vibrator axis to break the rock stratum, while the drill pipe does not rotate, and the vibration is not transmitted to the drill pipe by means of vibration absorber. The reverse circulation of compressed air is used to wash the well, so that the cuttings are discharged out of the well through the inner cavity of the pipe and drill pipe in the center of the vibrator. This kind of drilling rig has simple structure and high drilling efficiency. The borehole diameter is about 600mm and the drilling depth can reach 150m.
By the vertical reciprocating movement of drilling tools, the bit strikes the bottom of the hole to break the rock stratum. Its structure is simple, but there is no circulation well flushing system, so the cuttings removal and drilling machine can not be carried out at the same time, so the work efficiency is low. The drilling depth is generally less than 250m, and some can reach 500m-600m. The main types are as follows. A simple percussive drill that uses the weight of the drilling tool to impact the formation. The lower end of the drilling tool is several open angle claw valves. When the drilling tool moves downward under the action of its own weight, the grab valve opens, and each claw tip cuts into the rock stratum on the circumference of about 1 m in diameter, and then the winch lifts the drilling tool through the wire rope. During the closing process of the grab valve, the cuttings are caught into the cone body, and then the grab valve is opened to unload the rock cuttings. The drilling depth of the percussion and grabbing cone is usually 40-50m, and the maximum depth is 100-150m.
The wire rope percussive drilling rig is composed of mast and lifting pulley at its top, steel wire rope, impact mechanism, drilling tools (including drill pipe and drill bit), motor, etc. (Fig. 4). During operation, the motor drives the impact mechanism through the transmission device to drive the wire rope to make the drilling tool move up and down. When the drill moves downward, the weight of the drilling tool makes the bit cut into and break the rock stratum, while the upward movement depends on the traction of the wire rope. The falling height of drilling tool, i.e. stroke size, is determined according to rock conditions, generally 0.5-1 m, and large value is used for hard rock; the impact frequency is usually 30-60 times / min. The cut cuttings can be cleaned off the ground with a sand extraction barrel, or a barrel drilling tool that integrates the bit and the sand extraction barrel. Drilling and removing rock cuttings can be carried out at the same time, so that the cuttings can directly enter the extraction barrel, and then the drilling tool will be lifted to pour out the cuttings. In order to improve the wear resistance and drilling speed of the bit, tungsten steel powder is often overlaid on the end of the bit to form alloy repair welding bit.
There are two types: one is to add impact mechanism to rotary drilling rig on the basis of rotary drilling rig, mainly rotary drilling. When encountering pebble layer, dual-purpose water well drilling rig with impact drilling has strong adaptability to various formations; the other is well drilling rig combining impact and rotary action, such as pneumatic DTH hammer drill. The DTH hammer drilling tool (Fig. 5) is composed of a cylinder liner and a piston moving up and down in the cylinder liner. The lower end of the cylinder liner is connected with the drill bit, and the upper end is connected with the drill pipe through a threaded joint. The high-pressure air of 0.7-1.4 MPa provided by the air compressor passes through the check valve above the piston, the air distributor and the air inlet under the piston, which pushes the piston impact frequency as follows The reciprocating motion of 700-1200 times / min makes the piston frequently impact the bit, so as to enhance the ability of the bit to drill into the rock stratum. At the same time, the drilling tool rotates at a lower speed of 35-60 rpm.
The air discharged from the upper and lower cavities of the piston enters the drill bit downward to cool the bit and bring the cuttings from the bottom of the hole out of the wellhead. The structure of the rotary and circulating well washing parts is basically the same as that of rotary rotary rotary drilling rig with compressed air. The bits used are tungsten carbide ball tooth bits or cone bits. Pneumatic DTH hammer drilling machine can be used for drilling deep wells in hard rock stratum with high drilling speed, and the drilling speed does not decrease with the increase of drilling depth, and the drilled hole is straight.
In order to meet the needs of drilling in different formations and improve the drilling efficiency, water well drilling rigs are developing in the direction of multi-purpose drilling rigs and full hydraulic transmission and operation: a drilling rig is equipped with a variety of equipment and accessories, and can adopt various drilling methods such as percussive, rotary and DTH hammers; and it can also use mud washing, compressed air washing and forward and reverse circulation well washing.
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