JPH06229184A - Method and device for deep-well excavation construction - Google Patents

Abstract

PURPOSE:To excavate a boring pit having the high bottom hole water pressure of groundwater by compressed air at low pressure by using a down-hole drill without employing a booster compressor. CONSTITUTION:Valves 7 are installed to drill strings 6 at intervals along the longitudinal direction of the drill strings. Water in sections upper than the valves is removed by ejecting compressed air in order from the upper valves, water pressure on a bottom hole is reduced, and a down-hole drill 4 is driven by using a general-purpose compressor at low pressure and soil is excavated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep well excavation method and an apparatus therefor, and relates to a boring excavation technique using compressed air. Especially, by using a general-purpose portable low-pressure compressor, it is possible to dig deep into the groundwater layer, which was previously impossible, and it is not only the normal circulation method for air drilling but also the reverse circulation method and deep well pumping. Is also available.

[0002]

2. Description of the Related Art Boring excavation technology using compressed air (air excavation technology) has been rapidly developed in groundwater development, hot spring, geothermal, or underground resource exploration boring. In the conventional air excavation technology, when the groundwater layer is encountered during excavation, the depth at which the groundwater pressure corresponds to the maximum discharge pressure of the compressor is the limit of excavation. Further, since back pressure for removing the cutting waste during excavation together with groundwater is also generated, the limit of the excavation depth of the groundwater layer is to a head pressure lower than the maximum pressure of the air compressor used.

According to recent air drilling technology, a booster compressor is used for hot spring development and the like to drill a few hundred meters below the water table. However, handling ultra-high pressure air is dangerous and power consumption is high. Is extremely large and expensive. FIG. 2 shows the arrangement of such a conventional device, 1 is a deep well excavator, 2 is a boring hole, 3 is a bit, 4 is a down-the-hole drill, and 5 is a conventional drill string. The air compressor 30 discharges compressed air of 8 to 24 kgf / cm ^{2 to} the receiver 31, and the booster compressor 32 boosts this to a required pressure and supplies it to the deep well excavator 1. The required pressure is higher than the water pressure of the ground water at the bottom of the hole, and becomes extremely high pressure when the depth of the hole reaches several hundred meters.

However, such ultra-high pressure air is required only when the excavation is interrupted and groundwater is filled in the borehole to increase the water pressure at the bottom of the borehole. That is,
When drilling is interrupted by adding drill pipes or exchanging bits, groundwater will boil into the holes to maintain the natural groundwater level 20, and the head pressure of groundwater will act on the bottom of the holes. In order to restart excavation in this state, it is necessary to remove the groundwater in the hole with an air pressure exceeding the head pressure of the hole bottom, and as described above, the ultrahigh-pressure booster compressor is required.

On the other hand, the air pressure required for normal excavation without hydraulic head pressure is the sum of the back pressure in the flushing state and the friction loss consumed by the drill string, and the down-the-hole drill is used. In any case, the driving pressure of the down-the-hole drill is only added. Specifically, the back pressure during flushing is 2 kgf / c.
m ^2, the drill string in the loss of 1 kgf / cm ^2, the driving pressure of the down-the-hole drill is 5~7kgf / cm ² or so, the pressure of the air compressor in the excavation in the absence of action of the head pressure is 8~10kgf / cm It is about ² .

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to perform deep well drilling in a groundwater layer by using only a general-purpose compressor having a pressure necessary for drilling, without using a dangerous and large-sized and expensive booster compressor. The purpose is to provide an economical and safe deep well excavation method and equipment for groundwater development and underground resource exploration boring.

[0007]

According to the present invention, when a deep well is drilled by using compressed air as a drilling fluid for boring, water in the hole above the boring hole is pumped by compressed air from a shallow position. It is a deep well excavation method characterized by eliminating the hole bottom water pressure to excavate a deep well using low pressure compressed air. That is, at a position with a low water head pressure and a shallow depth in the boring hole, water above the position is removed using compressed air, and by repeating this, the water is sequentially drained in multiple stages, and finally the bottom of the hole. It is possible to drive the down-the-hole drill by discharging the water pressure to the part close to, reducing the water pressure at the hole bottom, and using low-pressure compressed air.

A device capable of suitably carrying out this method may be a deep well drilling device equipped with a compressed air driven down-the-hole drill and a valve for bypassing the compressed air in the middle of the drill string. ,
A valve whose operating pressure can be adjusted so that it opens and closes according to the pressure of compressed air and the water level in the hole is used, and multiple valves with different valve operating pressures are spaced in the length direction of the drill strings. By arranging them open, it is possible to sequentially drain water. Also, in order to carry out this in sequence, it is sufficient to arrange so that the operating pressure of the valve becomes higher from the bottom to the top, and the operating pressure of the valve at the bottom end is higher than the driving pressure of the down the hole drill. By setting so that the operating pressure of the uppermost valve is lower than the discharge pressure of the compressor, the water in the boring hole is automatically drained and the drilling is started. be able to.

[0009]

According to the method of the present invention, in a deep well drilling device using compressed air as the drilling fluid for boring, the water in the boring hole is pumped out by using compressed air in order from the top with the lowest head pressure. This is an epoch-making technology that enables the drilling of deep wells in the groundwater layer by lowering the water pressure and using the low-pressure compressor to drive the drilling equipment at the bottom without using the booster compressor.

As a method for removing the water in the boring hole by pumping, the compressed air supplied to the drill pipe is discharged into the groundwater through a valve provided in the middle of the drill string, and the air lift pump action and the flushing action cause the inside of the hole to be removed. It removes water to the ground. The valves that release compressed air from the drill strings are arranged in multiple stages at appropriate intervals in the drill strings so that the release depths are different, and the head with a low head pressure depending on the pressure of the compressed air and the water level in the hole. To open and close sequentially,
The structure is such that the operating pressure of the valve can be adjusted.

The valve at the bottom of the drill string is
For down-the-hole drill use, adjust to operate at slightly higher pressure than the down-the-hole drill drive pressure, and adjust top valve to operate at slightly lower pressure than compressor discharge pressure. To do. By using a drill string equipped with such a valve, it is possible to perform deep well drilling in the groundwater layer without using a dangerous and large and expensive booster compressor, and to develop economical and safe groundwater and underground resources. Exploration drilling will be possible, or pumping will be possible.

The operation of the device of the present invention is as follows.
The drill strings are provided with a plurality of valves arranged along the longitudinal direction at appropriate intervals so that the release depth of compressed air is different, and the operating pressures of these valves are the air pressure in the drill pipe and the water pressure in the hole. According to the above, adjustment is made so that the hydraulic head pressure is sequentially opened and closed from the top to the bottom.

When the compressed air from the compressor is sent to the drill strings, if the head pressure at the bottom of the hole is smaller than the pressure of the compressor, the compressed air is passed through the bit attached to the lower end of the drill string to the hole wall. It flows into the gap between the drill pipe and the drill pipe, pushes up the water in the hole, and enters the flushing state, enabling excavation. When the water head pressure at the bottom of the hole is higher than the pressure of the compressor, the air flow stops when the pressure of the compressed air and the water head pressure are balanced. At this time, for example, when the groundwater level reaches the mouth of the boring hole, the valve installed at the top is adjusted to open at a pressure slightly lower than the compressor pressure, so that the pressure in the drill strings is reduced. When this pressure rises to this operating pressure, it operates to expel the compressed air in the drill pipe into the groundwater, eliminating groundwater above this valve by airlift pumping and flushing actions. On the other hand, the valve arranged vertically below the valve in operation is designed to open at a pressure slightly lower than that of this valve, but since the head pressure acting on the valve is large, it may operate. Can not.

When the water above the valve is removed by the operation of the valve during operation, the head pressure acting on the valve is reduced, and at the same time, the pressure in the drill strings is also reduced. Also, the compressed air pressure in the drill strings drops and the valve closes. At this time, the next lower valve is adjusted to operate at a set pressure that is slightly higher than the head pressure to the next valve, so the next lower valve opens and the water above it is opened. Exclude. In this way, every time the internal pressure of the drill pipe and the water head pressure are balanced, the valve is opened to remove the water above it, and the water level is gradually lowered. When the bottommost valve completes drainage above it, the compressed air will eventually actuate the down-the-hole drill, flushing through the bit and resuming drilling. And this excavation will continue as long as the pumping volume is larger than the groundwater discharge.

For the maximum excavation water depth Dm, a concrete numerical value as a guide can be obtained by the following simple calculation. Dm = Vi × Vn + (Pc−Pf) × 10 (1) Pd <Pv <Pc (2) Vi = (1/2) Pc × 10 (3) Vn ≦ Pc−Pd (4) Where : Dm is the maximum drilling water depth (m) Vi: Valve arrangement interval (m) Vn: Number of valve arrangement steps (anonymous integer) Pc: Compressor maximum discharge pressure (kgf / cm ² ) Pf: Flushing back pressure (kgf) / Cm ² ) Pd: Driving pressure of down the hole drill (kgf / cm
² ) Pv: operating pressure of valve (lower stage <upper stage) (kgf / cm
² ) Formula (1) is a measure of the depth (D
m) is calculated and is not necessarily the limit value of excavation. Expression (2) determines the settable pressure range of the valve to be installed. Formula (3) determines the arrangement interval of the valves with reference to the capacity of the compressor, and the relationship with the water head is set to 1/2 of the compressor pressure as a guide. 0 <Vi <Pc ×
Eq. (3) will be used so that adjacent valves work well with each other, possible in the range of 10. The number of valve stages that can be arranged is calculated by the equation (4). If the operating pressure difference between the adjacent valves is made too small, it is necessary to finely adjust the pressure of the valves, and the valve structure becomes complicated, so that it cannot be mounted on a thin pipe. Therefore, considering that the operating pressure difference is 0.5 to 1 kgf / cm ² ,
The value obtained by the equation (4) is converted into an integer to obtain the number of valve stages.

FIG. 7 shows an example of a valve arrangement according to the present invention. A drill string 6 having a compressed air driven bit 3 at the bottom of a boring hole 2 is provided with valves 7 at regular intervals Vi. There is. When the water level 20 in the hole is high, compressed air is ejected from the valve above to eliminate water above it. The operating pressure of the valve is P from top to bottom
If v ₃ , Pv ₂ and Pv ₁ , then Pv ₃ > Pv ₂ > Pv
_{Is 1} .

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. In FIG. 1, a deep well drilling machine 1 is drilling a boring hole 2, and a down-the-hole drill 4 equipped with a bit 3 is attached to the lower end of a drill string 6 in the boring hole 2. This device does not include the booster compressor 32 of FIG. The drill strings 6 have several valves 7 arranged at appropriate intervals.
The valve 7 is shown in detail in its embodiment in FIGS.
3 is a front view of the valve, and FIG. 4 is a sectional view thereof.

In FIGS. 3 and 4, a valve body 9 is provided between the drill pipes 8 and 8 and a valve 10 is provided. The valve seat 12 is fixed to the valve body 9 by a snap ring 11, and the outer diameter of the valve seat 12 is sealed by an O-ring 13. The valve guide 14 holds the valve 10 via a disc spring 15. The valve 10 is screw-connected to the valve guide 14, and the valve guide 14 is incorporated in the valve seat 12 via a spring. Therefore, when the valve guide 14 is pressed so as not to rotate and the valve 10 is tightened, the biasing force of the disc spring 15 increases, and the plate 18 made of a flexible material attached to the valve 10 is strongly pressed to the valve seat 12. The operating pressure of the valve can be increased. On the contrary, if the valve 10 is loosened, the operating pressure becomes low. In this way, the operating pressure of the valve can be adjusted.

FIG. 5 shows a state in which the valve is operating. The valve 10 opens against the biasing force of the disc spring 15,
The state is shown in which the compressed air 21 is discharged through the valve and is flowing as indicated by arrow 22. FIG. 6 shows an example in which the valve is applied to a double-circle drill pipe for reverse circulation, 16 is an outer pipe drill pipe, and 17 is an outer pipe drill pipe.
Is an inner tube, and 23 is a hole wall.

Next, a specific example will be described with reference to FIG. Compressor pressure Pc = 8 kgf / cm ² Flushing pressure Pf = 2 kgf / cm ² Down the hole drill drive pressure Pd = 5 kgf / cm ²
Then, Vi = (1/2) / 8/10 = 40 Vn = 8-5 = 3 Dm = 40 × 3 + (8-2) × 10 = 180 The operating pressure Pv of the disposed valve is calculated from the equation (2). 5 <Pv <8
, Pv ₁ = 6.5, Pv ₂ = 7, Pv
Assuming ₃ = 7.5 V ₀ = 180−Vi × 3 = 60 Now, it is assumed that there is a water level on the ground surface. The water pressure acting on each valve is Pv ₃ = 6, Pv ₂ = 10, Pv ₁ = 16. When the blowing of compressed air is started, the internal pressure is 7.5 kgf /
All valves are closed until cm ² is exceeded and P
v ₃ of the valve to release the compressed air to open. When the water of V ₀ is pumped and discharged and the water level is lowered, the water pressure acting on the valve of Pv ₂ is also lowered to become Vi + Pf. Vi = 40
Since m and Pf = 2, the water pressure at this time is 6 kgf / cm
It becomes ² . In this process, since the internal pressure falls below 7.5 kgf / cm ² , the Pv ₃ valve closes, and naturally compressed air is discharged from the Pv ₂ valve.

In the process in which the water level lowers and the water pressure acting on the Pv ₁ valve eventually becomes 6 kgf / cm ² , compressed air is released from the Pv ₁ valve and finally the hole bottom pressure is 6 kgf / cm 2. ² , so the compressor pressure is 8
Groundwater can be pumped from the bottom of the hole even if the flushing pressure is subtracted from kgf / cm ² . In this way, in the flushing state, the internal pressure is reduced to ² kgf / cm ^2, and the down-the-hole drill can be driven.

[0022]

As described above, according to the present invention, in a deep well excavating device which uses air as a drilling fluid for boring, the hole bottom water pressure is lowered by pumping out the water in the hole in order from the lower head pressure. By utilizing this, deep well drilling in the groundwater layer can be performed without using a large and expensive booster compressor that is dangerous, and economical and safe groundwater development and hot spring, geothermal, underground resource exploration drilling can be performed. It is a groundbreaking thing that can be done. The device of the present invention can also be used as a pumping device for deep wells.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an arrangement of a drilling device of the present invention.

FIG. 2 is an explanatory diagram showing an arrangement of a conventional excavating device.

FIG. 3 is a front view of a valve.

FIG. 4 is a sectional view of a valve.

FIG. 5 is an operation state diagram of the valve.

FIG. 6 is a cross-sectional view of a double pipe valve.

FIG. 7 is an explanatory diagram of the present invention.

[Explanation of symbols]

1 Deep Well Excavator 2 Boring Hole 3 Bit 4 Down The Hole Drill 5,6 Drill Strings 7 Valve 8 Drill Pipe 9 Valve Body 10 Valve 11 Retaining Ring 12 Valve Seat 13 O-ring 14 Valve Guide 15 Disc Spring 16 Outer Pipe Drill Pipe 17 Inside Pipe 23 Hole wall 30 Air compressor 31 Receiver 32 Booster compressor

Claims (7)

[Claims] 1. When drilling a deep well by using compressed air as a drilling fluid for boring, the bore water above the borehole is removed by compressed air from a shallow position in the borehole to reduce the bore bottom water pressure. A deep well excavation method characterized by excavating a deep well using low pressure compressed air. 2. A deep well drilling device comprising a compressed air driven down-the-hole drill and a valve for bypassing compressed air in the middle of a drill string. 3. The deep well excavation according to claim 2, wherein the valve is capable of adjusting an operating pressure of the valve so as to open and close according to a pressure of compressed air and a water level in the hole. apparatus. 4. The deep well excavating device according to claim 3, wherein a plurality of valves having different operating pressures of the valves are arranged at intervals in the length direction of the drill string. 5. The deep well drilling device according to claim 4, wherein the valve is arranged such that the operating pressure of the valve increases from bottom to top. 6. The deep well excavating device according to claim 4, wherein the operating pressure of the valve at the lowermost end is set to operate at a pressure higher than the driving pressure of the down-the-hole drill. 7. The deep well excavating device according to claim 4, wherein the operating pressure of the uppermost valve is set to operate at a pressure lower than the discharge pressure of the compressor.