CN105089500A - Coal mine downhole hydraulic jet tree-shaped drill hole way-type drilling unit - Google Patents

Abstract

The invention relates to a coal mine underground hydraulic jet tree drilling combination drilling tool. The device includes six parts: a drill rod, a guide, a drill bit, a high-pressure hose, a self-propelled drill bit and a dial. The front end of the drill pipe and the guide is threaded, and the drill bit and the tail end of the guide are connected by threads; the combination of the drill pipe, the guide and the drill bit can simultaneously complete the two steps of reaming and feeding the guide; after the reaming is completed, The tree boreholes are drilled in the coal seam using a high-pressure hose and a self-propelled drill bit; the uniformity of the distribution of the tree boreholes is controlled by a dial. The main function of the invention is to drill into the mother hole of the tree-like borehole of the coal seam and the tree-like borehole, so as to realize uniform anti-permeability of the coal seam. The invention has simple structure and convenient operation, and is suitable for drilling tree-like boreholes in the process of gas drainage in low-permeable coal seams.

Description

Coal Mine Underground Hydrojet Tree Drilling Assembly Drilling Tools

technical field

The invention relates to the underground drilling technology of coal mines, in particular to a drilling tool used for self-advancing drilling into tree-shaped drilling holes in the gas drainage process of low-permeable coal seams.

Background technique

Many coal seams in my country have the characteristics of low permeability, etc., and conventional methods are difficult to effectively extract gas from coal seams with low permeability. How to increase the air permeability of coal seams is the key to solving the problem of gas drainage in low permeability coal seams.

As an effective reservoir permeability enhancement technology, hydraulic technology provides a feasible method to solve the problem of low permeability of coal seam, and is an effective way to increase the permeability of coal seam. Hydraulic technology uses high-pressure water as the driving force to expand and extend the original cracks in the reservoir or artificially form new holes, slots, cracks, etc., to promote the displacement of the rock mass and achieve the purpose of releasing pressure and increasing permeability of the reservoir, such as water jet cutting Fracture (or reaming, drilling), hydraulic fracturing, etc. As a new type of hydraulic anti-reflection technology, hydraulic jet tree drilling coal seam anti-reflection technology uses high-pressure water as the power to make the self-propelled drill bit advance in the mother hole of the rock formation, and after reaching the predetermined position of the coal seam, it passes through the guide Orientation, so as to drill vertical tree-shaped sub-holes, so as to achieve the effect of increasing the permeability of the coal seam. Hydrojet dendritic drilling coal seam anti-permeability technology is an efficient and safe gas pre-extraction method, which can shorten the total length of drilling, thereby saving drilling costs and shortening drilling time; realizing uniform anti-permeability in low-permeability coal seams; It will produce sparks and coal dust, increase the safety of work, improve the working environment and other advantages.

Currently, the drilling tools used for hydrojet tree drilling in coal mines are separate and independent. To realize the steering of the high-pressure hose in the guide, the female hole must meet a certain diameter requirement. Therefore, after the female hole is drilled with an ordinary drill bit, it is necessary to use a reaming drill to ream the hole. Although the existing reaming drill bits in coal mines can drill holes that meet the requirements, because the drilling and guide are sent separately, it often takes a lot of time and increases the workload. There may also be cases of collapsed holes.

In addition, the current guide is unreasonable in the design of the guide track. First, there is usually only one curvature, and it is difficult for the high-pressure hose to turn; second, the width of the steering guide track is not properly designed. The drill bit is stuck, and if it is too large, it cannot play a practical restraint role. In addition, the current guider does not consider the problem of slag discharge when drilling tree-shaped holes. The guider has a small annular space and cannot discharge slag smoothly, thus affecting the smooth advancement of the drill bit.

In addition, self-propelled drill bits are required for hydraulic jet tree drilling in coal mines, and self-propelled drill bits need to cooperate with guides. The current drill bits have the following problems: 1) The drill bit or nozzle has a complex structure, large size, and poor steering ability. Short service life; 2) The efficiency of water jet rock-breaking drilling is low during long-distance drilling; 3) The drilled holes are small in size, easy to jam the drill bit, and difficult to remove slag; The rock effect is poor, and it is easy to form a boss in the center of the drill hole, which hinders the advancement of the drill bit; 5) The self-progressive force generated by the drill bit is small, the hole trajectory is difficult to control, and it is easy to drill a partial hole.

Contents of the invention

The purpose of the present invention is to aim at the above-mentioned deficiencies existing in the prior art, and to provide a coal mine hydraulic jet tree-shaped drilling combination drilling tool, which combines a drill pipe, a guide, a drill bit, a high-pressure hose, a self-propelled drill bit and a dial Make a reasonable combination and optimize the structure of the drill pipe to reduce the resistance of the high-pressure hose passing through; optimize the structure of the guide so that the guide can be used in conjunction with the drill bit; optimize the structure of the drill bit to improve the drilling efficiency; select the appropriate The high-pressure hose optimizes the structure of the self-advancing drill at the front end of the high-pressure hose; the dial is designed so that the tree-like drilling can be evenly distributed.

Technical solution of the present invention is as follows:

Underground coal mine hydrojet tree drilling assembly includes drill pipe, guider, drill bit, high-pressure hose, guide dial and self-propelled drill bit.

Among them, the drill pipe, the guide and the drill bit are connected in sequence, and they are used together when reaming. The high-pressure hose, self-propelled drill bit and dial are used when drilling tree-shaped holes. A steering dial is installed on the chuck connected to the front end of the drill pipe and the drill rig. One end of the dial is fixed on the drill pipe and moves with the drill pipe. Rotate, the other end is fixed on the drill chuck, the rotation angle of the guide is controlled by the dial, the self-propelled drill bit is connected to the front end of the high-pressure hose, and when drilling into a tree-shaped hole, it passes through the drill pipe and is guided by the guide, relying on the nozzle The jet generates self-progressive force to drill out tree-like holes.

The diameter of the drill pipe is consistent with the diameter of the commonly used drill pipe for underground gas drainage in coal mines, with an outer diameter of 73mm and an inner diameter of 50mm; the front and rear threads of the drill pipe are designed according to national standards for easy connection; the inside of the drill pipe is a smooth through hole , the high-pressure hose can pass through smoothly.

The diameter of the guide is 100-150mm. The upper end of the guide is a drill pipe connecting portion with an internal thread, and the lower end is a drill bit connecting portion with an external thread, and the two connecting portions have through holes connecting up and down. There is a double-curvature turning guide track in the guide, whose width is twice the width of the nozzle at the front end of the high-pressure hose, ranging from 20-50mm, and the turning radius is 75-150mm. It is an ultra-short radius radial horizontal well guide.

The track axes of the inlet direction and the outlet direction of the guide track are perpendicular to each other, that is, from the axial direction to the radial direction. Two arc segments.

The axial straight pipe section has a length of 30-50mm, and the through hole of the drill pipe connection part transitions to the axial straight pipe section through an oblique contraction section.

The arc radian of the first arc segment is a=10°-30°, and the diameter is 75-150mm.

The inclined pipe section is tangent to the two arc sections and connects the first arc section and the second arc section.

The arc radian of the second arc section is b=a+90°, and the diameter is 75-130mm; fine holes are distributed at the bottom of the second arc section, and the high-pressure water flow of the guide track can pass through the fine holes and connect Part of the through hole reaches the drill bit; the end of the second arc section is the exit position of the guide rail, and a hollow spiral ring is installed. When the combined drilling tool is used for reaming, the circular cement block is fixed on the hollow spiral ring to seal the guide rail. track exit.

The wall of the guide track is provided with four rollers, the radius of the rollers is 4-5mm, protruding from the track wall by about 2mm; and one roller is arranged on the first arc segment, and three rollers are arranged on the second arc segment. scroll wheel.

The size of the drill bit is consistent with the size of the commonly used drill bit for underground gas drainage in coal mines. The drill thread is a standard thread, which is convenient to connect with the guide; there is a flow channel connected to the connecting part of the guide inside the drill bit, so that the water flow can pass through the guide and then pass through the drill bit. , in order to carry out slag discharge, the inner flow channel of the drill bit gradually narrows from top to bottom, and there is a section of enlarged space in the middle to form a cavitation structure, which can make the water flow used for slag discharge also have the effect of assisting rock breaking, and enhance the breaking effect. Rock efficiency; cinders generated by drilling are discharged from the drill bit annulus.

The self-advancing drill bit is connected to the front end of the high-pressure hose. The self-propelled drill bit includes a drill body and a central self-excited oscillation nozzle on the drill body, a side nozzle, a middle nozzle and a rear nozzle, and the drill body has a front platform and an internal cavity. The front part of the drill bit body is spherical, and the spherical front end surface is a platform. A central self-excited oscillation nozzle is arranged on the center of the platform, that is, the axis of the self-propelled drill bit. Side nozzles with deflection angle β; middle nozzles with deflection angle θ in the cross section are evenly distributed in the middle of the drill body, and the cross section refers to the plane passing through the axis of the middle nozzle and perpendicular to the axis of the drill bit; the rear end of the drill body is an open end, There are internal threads for connecting high-pressure hoses, and the rear nozzles are uniformly arranged on the side wall with a cone angle Φ to the axis of the drill body. The internal cavity of the drill body is a combined cavity of the front section conical and the rear section cylindrical , the taper of the conical segment is . The central self-excited oscillating nozzle and side nozzles of the self-propelled drill bit can break the coal and rock mass; the middle nozzle can spray high-speed jets vertically to the borehole during the drilling process of the self-propelled drill bit, so that the self-propelled drill bit and the wall of the drill hole are kept in good contact with each other. A certain distance can achieve the effect of righting the drill bit and avoid drilling deviation; the rear nozzle can provide a certain reverse thrust for the self-propelled drill bit to advance, and drive the high-pressure hose to pass through the drill pipe and the guide when drilling into a tree-shaped hole device, and break the circular cement block at the outlet of the guide, and finally carry out tree drilling. The rotation angle of the guide is controlled by a dial. When the drill pipe rotates, it drives the guide to rotate together, and the dial can display the rotation angle of the drill pipe, so as to obtain the rotation angle of the guide and provide a guarantee for the uniform distribution of tree-shaped drilling holes.

Using the combined drilling tool of the present invention, the ordinary drill bit is used to drill holes in the low-level roadway to the coal seam in advance, and the drilling tool of the present invention is used to ream the hole after the hole is formed to form the mother hole of the self-advancing hydraulic jet tree-like drilling, Then use the high-pressure hose and the self-propelled drill bit to drill into the tree-shaped holes in the coal seam at the predetermined position of the coal seam to achieve uniform anti-permeability of the coal seam.

The present invention has the following characteristics:

1. The combination drilling tool reasonably combines the drill pipe, guide, drill bit, high-pressure hose, self-advancing drill bit and dial, and can simultaneously complete the drilling of the tree-shaped drilling mother hole and the introduction of the guide, that is, Through the reaming of the drill bit, there is no need to withdraw the drill and install the guide after drilling, and the tree-shaped drilling of the coal seam can be drilled directly, which saves the time caused by the separate feeding of the drill and the guide device, and reduces the workload.

2. The size of the drill pipe used in the combined drilling tool is the same as that commonly used in coal mines, which facilitates the use and processing of the drill pipe; the inside of the drill pipe is a smooth through hole, and the high-pressure hose can pass through smoothly.

3. The drill pipe, guide device and drill bit of the combined drilling tool are connected with standard threads, which is convenient for processing and use. The drill pipe and the drill bit can be used alone as a reaming drill bit, or a guide device can be added to provide a guide track for tree drilling.

4. The radius of the guider of the combined drilling tool is short, and the resistance of the high-pressure hose to pass through is small.

5. The drill bit connected to the front end of the guide is a cavitation drill bit. The guide track of the guide device is connected with the flow channel of the drill bit connected to the front end. After the high-pressure water passes through the flow channel, it can assist rock breaking with lower water pressure and increase drilling. efficiency.

6. The self-advancing drill bit is an integrated structure, relatively simple in design, small in size, long in life, good in rock breaking, large in size, does not form bosses, and is not easy to deviate. Moreover, the high-pressure fluid generated by the pump enters the self-propelled drill bit through the high-pressure hose, and will be divided into four jets, so that the self-propelled drill bit has a good function of breaking rocks in stages.

7. When the high-pressure hose of the combined drilling tool is working, it can rely on the forward thrust generated by the high-pressure water and the crushing ability of the high-pressure water on the coal body to drill into the tree-shaped borehole.

8. Through the adjustment of the dial to the outlet direction of the guider, the uniform distribution of tree-shaped drilling holes can be realized, and the air permeability of the coal seam can be better improved.

It can be seen that the combination drilling tool involved in the present invention is suitable for use when drilling tree-shaped boreholes in the process of gas drainage in low-permeability coal seams. Predetermine the location of the coal seam, and use high-pressure hoses and self-propelled drill bits to drill tree-shaped holes in the coal seam, thereby improving the air permeability of the coal seam.

Description of drawings

Shown in Fig. 1 is drilling tool schematic diagram of the present invention;

Shown in Fig. 2 is the drill pipe structural representation of the present invention;

Shown in Fig. 3 is the structural representation of guide device of the present invention;

The fine hole for water flow to pass through on Fig. 4 guider;

Shown in Fig. 5 is the used hollow spiral ring and circular cement block of guide device of the present invention;

Shown in Fig. 6 is the drill bit structural representation of the present invention;

Shown in Fig. 7 is the drill bit structure end view of the present invention;

Shown in Fig. 8 is the left side view of self-propelled drill bit of the present invention;

Shown in Fig. 9 is the A-A sectional view of self-propelled drill bit of the present invention;

Shown in Fig. 10 is the BB sectional view of self-propelled drill bit of the present invention;

Shown in Figure 11 is the enlarged view of the center self-excited oscillation nozzle section of the self-propelled drill bit of the present invention;

Figure 12 is a schematic diagram of the deflection angle and opening angle of the self-advancing drill side nozzle of the present invention;

Shown in Fig. 13 is the comparison diagram of the rock-breaking effect of the self-advancing drill bit of the present invention and the traditional only with the axial angle drill bit;

Shown in Figure 14 is the dial front view of the present invention;

Figure 15 is a side sectional view of the dial of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the combined drilling tool that the present invention proposes comprises drilling rod (1), guide device (2), drill bit (3), high-pressure hose (4), self-propelled drill bit (5) and steering dial ( 6) etc. The drill rod (1), the guide (2) and the drill bit (3) are connected in sequence, and are used together when reaming. High-pressure hose (4), self-advancing drill (5) and steering dial (6) are used when drilling tree boreholes. One end of the steering dial is fixed on the drill rod and rotates with the drill rod, and the other end is fixed on the chuck of the drilling rig, and the rotation angle of the guide (2) is controlled by the steering dial. The front end of the high-pressure hose (4) of the present invention is equipped with a self-advancing drill bit (5), and the high-pressure hose can withstand a certain high pressure and has certain flexibility.

As shown in Figure 2, the diameter of the drill pipe (1) is consistent with the diameter of the commonly used drill pipe for underground gas drainage in coal mines, with an outer diameter of 73mm and an inner diameter of 50mm. The front and rear threads of the drill pipe are designed according to national standards, which is convenient for connection. The inside of the drill pipe is a smooth through hole, and the high-pressure hose can pass through smoothly. The drill rod is beneficial to accurately send the guide to the designated position and drive the guide to turn.

As shown in Figure 3, the upper end of the guide (2) is the drill pipe connecting portion (2.1), and the lower end is the drill bit connecting portion (2.10). There are through holes through each connecting portion up and down.

The guide (2) is equipped with a guide track for guiding the high-pressure hose. The track axes in the direction of the entrance and exit of the guide track are perpendicular to each other, that is, from the axial direction to the radial direction, and the entire guide track from the entrance to the exit consists of The specific designs of the axial straight pipe section (2.2), the first circular arc section (2.3), the inclined pipe section (2.4) and the second circular arc section (2.5) are:

The length of the axial straight pipe section (2.2) is 30-50 mm, and the lower end of the through hole of the drill pipe connection part (2.1) transitions to the axial straight pipe section (2.2) through an oblique contraction section.

The arc radian a of the first arc section (2.3) is 10°-30°, and the diameter is 75-150mm.

The inclined pipe segment (2.4) is tangent to the two arc segments, and connects the first arc segment (2.3) and the second arc segment (2.5).

The arc radian of the second arc segment (2.5) is b=a+90°, and the diameter is 75-130mm. It can be seen from Fig. 4 that there are thin holes (2.7) distributed at the bottom of the second arc segment (2.5), which communicate with the through holes in the connecting part (2.10). After the drill track, it reaches the drill bit through the fine hole (2.7) and the through hole of the connecting part (2.10), so that when the high-pressure water flow performs the slag discharge function, it can assist rock breaking with lower water pressure and increase the drilling efficiency. . As can be seen in conjunction with Figure 5, the end of the second arc segment (2.5) is the exit position of the guide rail, and a hollow spiral ring (2.8) is installed. The hollow spiral ring is a hollow inner hexagonal structure, and the ring is engraved with mounting threads. When using the combination drilling tool to carry out reaming, the circular cement block (2.9) is fixed on the hollow spiral ring (2.8), which is used to seal the guide track outlet. Therefore, the hollow spiral ring of the guide and the round cement block should be used when reaming and installed before reaming. The circular cement block can seal the outlet of the guide when the combined drilling tool is drilling, so that the high-pressure water flow of the guide track can reach the drill bit through the fine holes on the track. Although the strength of the circular cement block can withstand the pressure of the high-pressure water used in the drilling process of the combined drilling tool, the self-propelled drill bit can break the circular cement block and pass it through the guide.

Simultaneously, four rollers (2.6) are arranged on the wall of the guide track, the radius of the rollers is 4-5mm, protruding from the track wall by about 2mm, a roller is arranged on the first arc section (2.3), and a roller is placed on the second circle. Three rollers are arranged on the arc section (2.5), the function is to assist the drill bit of the high-pressure hose to guide correctly, and can effectively reduce the resistance of the high-pressure hose to pass through.

As shown in Fig. 6 and Fig. 7, the size of the drill bit (3) connected to the front end of the guider is consistent with the size of the drill bit commonly used for underground gas drainage in coal mines, and the drill thread is a standard thread, which is convenient for connecting with the guider. A part of the overall guide device of the drill bit can more easily send the guide device into the female hole when the female hole is not formed regularly and is obstructed, and at the same time can complete small-scale reaming. Inside the drill bit there is a flow channel (3.1) communicating with the through hole of the drill bit connection part (2.10) of the guide, so that the water flow can pass through the guide and then through the drill bit, so as to carry out slag discharge. The inner flow channel of the drill bit gradually narrows from top to bottom, and there is an enlarged space in the middle, forming a cavitation structure (3.2), which can make the water flow for slag discharge also have the effect of assisting rock breaking, and improve rock breaking efficiency. With this drill bit, the guide track of the guide device communicates with the flow channel of the drill bit connected to the front end, and after high-pressure water passes through the flow channel, it can assist rock breaking with relatively low water pressure, increasing drilling efficiency.

As shown in Figures 8 to 12, the self-propelled drill includes a drill body and a central self-oscillating nozzle (5.2), a side nozzle (5.3), a middle nozzle (5.4) and a rear nozzle (5.5) on the drill body. The front part of the self-propelled drill bit (5) is spherical, and the front end is a platform (5.1). The platform (5.1) reduces the overall size of the drill bit, which is convenient for drilling the center self-excited oscillation nozzle (5.2) and side nozzles ( 5.3), the radius R2 is 2.5mm-4.0mm. Side nozzles (5.3) with a certain opening angle α and deflection angle β are evenly arranged around the self-excited oscillation nozzle (5.2).

As shown in Figure 12, the definition of opening angle α and deflection angle β is as follows: on the front end surface of the conical section of the inner cavity, a certain distance from the axis of the drill bit is determined as the starting point c of the side nozzle, and the starting point c of the passing side nozzle and The straight line cc' parallel to the drill bit axis oo' is defined as straight line 1, and the plane oo'd'd defined by straight line 1 and the drill bit axis is defined as plane 1; with straight line 1 as the baseline, first move away from the direction of the side jet outlet in plane 1 The direction of the drill axis is deflected by a certain angle, and this angle is set as the opening angle α. At this time, the nozzle axis ce is defined as the line 2; then the line 2 takes the starting point of the side nozzle as the origin, and the line 1 as the rotation axis, and rotates a certain cone angle , the obtained nozzle axis cf is defined as straight line 3, which is the actual axis of the front nozzle. At this time, the included angle between the projections ec' and fc' of straight line 2 and straight line 3 on the cross-section of the self-advancing drill bit is set as the deflection angle beta. All side nozzles are evenly arranged in this way, and the angle and direction of deflection are consistent. The number of side nozzles (5.3) is 3-6, the nozzle diameter is 0.5mm-1.2mm, the distribution radius R1 is 1.0mm-2.0mm, and the opening angle α is between 15°-30°, the optimum is 25°, The deflection angle β is between 60°-90°, and the optimal value is 360°/n (n refers to the number of edge nozzles). The distribution radius R1 refers to the distance from the center of the jet outlet of the edge nozzle to the axis of the drill bit.

The middle part of the drill bit is evenly distributed with middle nozzles (5.4) with a certain deflection angle θ in the cross section, as shown in Figure 10, the cross section refers to the plane passing through the axis of the middle nozzle and perpendicular to the axis of the drill bit, and the deflection angle θ refers to the plane in the middle The angle between the axis of the nozzle and the radial radius. It can be seen from Fig. 10 that the number of nozzles (5.4) in the middle is 3-6, the nozzle diameter is 0.5mm-1.2mm, and the deflection angle θ is between 30°-45°. The main function of the nozzle in the middle is the righting function, and the effect of breaking rocks and repairing holes is relatively weak. At the same time, the moment generated by the recoil force of the jet can tighten the drill bit.

The rear end of the drill bit is an open end, and an internal thread (5.6) is provided inside for connecting a high-pressure hose, and a rear nozzle (5.5) with a certain cone angle Φ with the axis is evenly arranged on it, as shown in Figure 9, the cone angle Φ refers to the angle between the axis of the rear nozzle and the axis of the drill bit; the number of rear nozzles (5.5) is 6-8, the nozzle diameter is 0.5mm-1.5mm, and the axial cone angle Φ is between 10°-30° Between, the optimum is 25°.

Combining with Figure 9, it can be seen that the inside of the drill bit has a cone angle of The combined cavity (5.7) of the cone and cylinder, the cone angle of the conical section of the combined cavity is between 20°-45°, the cone angle The principle of selection is to minimize the local loss of the jet and facilitate processing.

It can be seen from Fig. 11 that the central self-oscillating nozzle (5.2) is arranged on the axis of the self-propelled drill bit, and consists of an upstream nozzle (5.8), a self-oscillating cavity (5.9) and a downstream nozzle (5.10). The length L of the self-excited oscillation cavity is generally 2.3 to 3.3 times the diameter d1 of the upstream nozzle, and the diameter d2 of the downstream nozzle is generally 1.2 to 1.3 times the diameter d1 of the upstream nozzle. The main body of the self-excited oscillation cavity (5.9) is a cylindrical cavity, and its diameter is 18 times the diameter of the upstream nozzle d1; the longitudinal section of the cavity is a parallelogram that is symmetrical up and down, and the collision wall of the upstream and downstream nozzles of the cavity is a conical surface, and The collision wall of the upstream nozzle is convex to the upstream, and the collision wall of the downstream nozzle is concave to the downstream.

The overall length of the self-advancing drill bit ranges from 14mm to 18mm, and the outer diameter ranges from 10mm to 14mm.

The self-advancing drill bit of the present invention can divide the high-pressure water into four jets, so that the drill bit has the function of breaking rocks in stages:

First, a part of the fluid passes through the central self-excited oscillation nozzle, relying on the self-excited oscillation chamber of the nozzle, transforms the continuous jet into a pulsed jet, improves the instantaneous striking force of the central jet, and takes the lead in generating the central crushing pit. The principle is: the upstream nozzle completes the formation of the jet beam in the cavity, and its geometric parameters and machining accuracy will affect the flow characteristics of the jet beam, the initial separation position of the shear layer, and the size of the disturbance. The self-excited oscillation cavity can form a feedback path, and the frequency can be selected according to different lengths and diameters. When the disturbance peak amplified by the shear layer reaches the downstream collision wall, it collides with it. Since the local cross-sectional area of the jet here is larger than the cross-sectional area of the downstream outlet, a pressure transient will be generated here due to the influence of velocity. The transient is reflected upstream along the jet axis at the speed of sound, and then produces a pressure transient at the upstream nozzle, thereby generating a strong disturbance here, which is transported downstream with the shear layer and amplified to reach the downstream Collisions occur again, resulting in pressure transients. Repeat back and forth in this way to form a positive feedback closed loop and form a self-excited oscillation. During this process, the energy of the fluid is gathered and released intermittently, forming a pulsed jet whose instantaneous energy is several times higher than that of a continuous jet. For the specific generation mechanism, see the generation mechanism of self-excited oscillation pulse jet.

Then, part of the fluid passes through the side nozzle with a certain opening angle and deflection angle, and the jet produced has three-dimensional velocities: axial velocity, radial velocity and hoop velocity, so that the rock is not only damaged by impact, but also sheared and stretched. Moreover, during the drilling process, the target distance between the drill bit and the rock is from far to near. Compared with the rock-breaking effect of the traditional drill bit with only an opening angle, the rock-breaking effect is shown in Figure 13: The erosion hole produced by the drill bit with deflection angle and opening angle can effectively form the central connecting hole, because the drilling process of the self-advancing drill bit is a dynamic process from far to near, that is, the process of moving target distance, so The action point of the water jet varies at different drilling times. For the drill bit with only opening angle, the trajectory of the jet action point is a straight line passing through the center, while for the drill bit with deviation angle and opening angle, the trajectory of the action point is a helical line, so the trajectory line is longer and the damage area is larger Larger, it is easier to make the crushing pit caused by each jet flow form a drill hole, so that the rock breaking effect is good, and the rock breaking drilling can be continued around the central crushing pit to form a pilot hole to make the drill bit advance.

Then, the jet formed by the middle nozzle with a certain deflection angle in the cross section has a radial component velocity and a tangential component velocity (the tangential velocity refers to the component velocity along the tangential direction of the peripheral wall of the drill bit.), the diameter of the jet flow The tangential speed can keep the drill bit in the air all the time, has the function of righting, keeps the drilling balance between the drill bit and the high-pressure pipe, and can prevent the drill bit from drifting to a certain extent; Reaming the hole again, and correcting the hole to make the shape of the hole more regular.

Finally, another part of high-pressure fluid will pass through the rear nozzle with a certain cone angle with the axis of the drill bit, and the generated jet will provide self-propelling force for the drilling of the drill bit and high-pressure pipe, and further reaming. In addition, due to the relatively large number of rear nozzles, a large number of backward jets have a good slag discharge function, and the backward jets have the same angle with the axis. The smaller the angle, the greater the recoil force of the jet. However, as the cone angle decreases, the deflection angle between the jet outlet direction and the inlet direction increases, the local pressure loss increases, and the jet velocity decreases, thereby reducing the self-propelled force, so the cone angle is generally between 10°-30° .

Referring to Fig. 14 and Fig. 15, a steering dial (6) is installed on the chuck connected between the drill rod and the front end of the drilling rig, and the rotation angle of the guide (2) is controlled by the steering dial. The steering dial is used when drilling into a tree-shaped hole after the reaming is completed. When in use, one end of the steering dial is fixed on the drill pipe and rotates with the drill pipe, and the other end is fixed on the drill chuck. The rotation angle of the drill pipe can be read through the steering dial, which can be read within a range of 360°. The rotation angle of the drill pipe is the rotation angle of the guide. Reasonable control of the rotation angle can achieve uniform distribution of tree-like drilling.

The working principle of the combined drilling tool described in the present invention is as follows: use common drill bits to drill holes in the low-level roadway coal seam in advance, use the drilling tool described in the present invention to ream the holes after the hole is formed, and form a self-advancing hydraulic jet tree-shaped drilling base. holes, and then use high-pressure hoses and self-propelled drill bits to drill tree-shaped holes at predetermined positions in the coal seam to achieve uniform anti-permeability of the coal seam.

The use process of the present invention is as follows:

①Before use, first use a common drill to drill holes where the gas is to be pre-pumped.

②Connect the guide (2) and the drill pipe (1) through the drill pipe connecting part (2.1), then connect the drill bit (3) and the guide (2) through the drill connecting part (2.10), and successively put the round cement Block (2.9), hollow spiral ring (2.8) are installed in the guide rail outlet.

③ Then use the drill bit (3) of the combined drilling tool to ream the hole, and the combined drilling tool can bring the guide (2) into the predetermined position in the female hole while reaming, eliminating the need for reaming back drill and guide Sending and other processes.

④ After arriving at the predetermined position, feed the high-pressure hose (4) and the self-advancing drill bit (5) from the drill pipe (1) so that they pass through the drill pipe and the guide in turn. The drill bit breaks the round cement block and drills the tree-shaped hole.

⑤ Control the exit direction of the guide through the reading of the dial (6), and drill holes in the same plane multiple times and uniformly. After completion, perform the same drilling on other planes of the same mother hole, and finally form a tree-like drilling.

The above descriptions are only illustrative specific implementations of the present invention, and are not intended to define the scope of the present invention. On the basis of the technology and solutions disclosed in the present invention, those skilled in the art can use the technical content disclosed in this patent without Creative labor can make some modifications and changes to some of the technical features, and these modifications and changes are all within the protection scope of the present invention.

Claims (3)

1. Underground coal mine hydraulic jet tree drilling assembly, including drill pipe (1), guide (2), drill bit (3), high-pressure hose (4), self-propelled drill bit (5) and steering dial (6); It is characterized in that: the drill pipe (1), the guide (2) and the drill bit (3) are connected in sequence, and are used in conjunction with reaming; the high-pressure hose (4), the self-propelled drill bit (5) and the steering The dial (6) is used when drilling into a tree-shaped hole. A steering dial (6) is installed on the chuck connected between the drill pipe and the front end of the drilling rig, and the rotation angle of the guide (2) is determined by the steering dial (6). Control, the self-propelled drill bit (5) is connected to the front end of the high-pressure hose (4), and when drilling into a tree-shaped hole, it passes through the drill pipe (1) and is guided by the guide (2), relying on the nozzle jet to generate self-propelled force to drill out dendritic hole; The diameter of the drill pipe (1) is consistent with the diameter of the commonly used drill pipe for underground gas drainage in coal mines. Its outer diameter is 73mm and its inner diameter is 50mm; The through hole, the high pressure hose can pass through smoothly; The diameter of the guide (2) is 100-150mm; The upper end of the guide (2) is a drill pipe connecting portion (2.1) with an internal thread, and the lower end is a drill bit connecting portion (2.10) with an external thread, and both connecting portions have through holes that penetrate up and down; The guide (2) has a double-curvature turning guide rail, the width of which is twice the width of the nozzle at the front end of the high-pressure hose, the range is between 20-50mm, and the turning radius is 75-150mm, which belongs to the ultra-short radius radial water rail. flat well guide; The track axes of the entrance direction and the exit direction of the guide track are perpendicular to each other, that is, from the axial direction to the radial direction, and the whole guide track from the entrance to the exit sequentially includes an axial straight pipe section (2.2), a first circular arc section (2.3 ), the inclined pipe section (2.4) and the second arc section (2.5); The axial straight pipe section (2.2) has a length of 30-50 mm, and the through hole of the drill pipe connection part (2.1) transitions to the axial straight pipe section (2.2) through an oblique contraction section; The arc radian of the first arc segment (2.3) is a=10°-30°, and the diameter is 75-150mm; The inclined pipe section (2.4) is tangent to the two arc sections, and connects the first arc section (2.3) and the second arc section (2.5); The arc radian b=a+90° of the second arc segment (2.5) has a diameter of 75-130mm; a thin hole (2.7) is distributed at the bottom of the second arc segment (2.5), so that the guide track The high-pressure water flow can reach the drill bit (3) through the through hole of the connecting part (2.10) through the fine hole; the end of the second arc segment (2.5) is the exit position of the guide track, and a hollow spiral ring (2.8) is installed. When the tool is reaming, the circular cement block (2.9) is fixed on the hollow spiral ring (2.8) to seal the guide rail exit; The wall of the guide track is provided with four rollers (2.6), the radius of the rollers is 4-5mm, protruding from the track wall by about 2mm; Three rollers are arranged on the arc section (2.5); The size of the drill bit (3) is consistent with the size of the commonly used drill bit for underground gas drainage in coal mines, and the drill thread is a standard thread, which is convenient to be connected with the guide; The water flow can pass through the guide and then pass through the drill bit for slag discharge. The inner flow channel of the drill bit gradually narrows from top to bottom, and there is an enlarged space in the middle to form a cavitation structure (3.2). The water flow used for slag discharge is also It has the effect of assisting rock breaking and improving the efficiency of rock breaking; the cinder generated by drilling is discharged from the annulus of the drill bit. 2. The coal mine underground hydraulic jet tree drilling combination drilling tool according to claim 1, characterized in that, the self-propelled drill bit comprises a drill bit body and a center self-excited oscillation nozzle (5.2) on the drill bit body, a side nozzle (5.3), the middle nozzle (5.4) and the rear nozzle (5.5), the drill bit body has a front platform (5.1) and an internal cavity (5.7); the front part of the drill bit body is spherical, and the spherical front end surface is a platform ( 5.1), the central self-excited oscillating nozzle (5.2) is set on the center of the platform, that is, the axis of the self-propelled drill bit, and side nozzles ( 5.3); the middle part of the drill body is evenly distributed with a middle nozzle (5.4) with a deflection angle θ in the cross section, and the cross section refers to a plane passing through the axis of the middle nozzle and perpendicular to the axis of the drill bit; the rear end of the drill body is an open end, set There are internal threads (5.6) for connecting high-pressure hoses, and the rear nozzles (5.5) that form a cone angle Φ with the axis of the drill body are evenly arranged on the side wall, and the internal cavity (5.7) of the drill body is conical in the front section and The combined cavity of the rear section is cylindrical, and the taper of the conical section is The radius R2 of the platform (5.1) is 2.5mm-4.0mm, the number of side nozzles (5.3) is 3-6, the nozzle diameter is 0.5mm-1.2mm, and the distribution radius R1 around the center of the platform is 1.0mm-2.0 mm, the opening angle α is between 15°-30°, and the deflection angle β is between 60°-90°; the setting of the side nozzle is: the front end surface of the conical section of the inner cavity (5.7) is a certain distance from the axis of the drill bit The point determined by the distance is the starting point of the side nozzle, and the straight line passing through the starting point of the side nozzle and parallel to the axis of the drill bit is defined as straight line 1, and the plane defined by straight line 1 and the axis of the drill bit is defined as plane 1; The direction away from the axis of the drill bit is deflected by a certain angle, and this angle is set as the opening angle α; at this time, the axis of the nozzle is defined as the line 2; then the line 2 takes the starting point of the side nozzle as the origin, and the line 1 as the rotation axis, and rotates a certain cone angle , the obtained nozzle axis is defined as line 3, which is the actual axis of the side nozzles. At this time, the included angle projected by line 2 and line 3 on the cross-section of the self-advancing drill bit is set as the deflection angle β; all side nozzles are set according to This method is evenly arranged, and the deflection angle and direction are consistent; The number of said middle nozzles (5.4) is 3-6, the nozzle diameter is 0.5mm-1.2mm, the deflection angle θ is between 30°-45°, and the deflection angle θ refers to the axis of the middle nozzle and the radial radius Angle; The number of the rear nozzles (5.5) is 6-8, the nozzle diameter is 0.5mm-1.5mm, the axial cone angle Φ is between 10°-30°, and the axial cone angle Φ refers to the The angle between the axis and the axis of the drill bit. The overall length of the drill bit ranges from 14mm to 18mm, and the outer diameter ranges from 10mm to 14mm. 3. The coal mine underground hydraulic jet tree drilling combination drilling tool according to claim 2, characterized in that: the self-excited oscillation nozzle (5.2) is sequentially composed of an upstream nozzle (5.8), a self-excited oscillation cavity (5.9) and The downstream nozzle (5.10) is composed of; the length L of the self-excited oscillation cavity is 2.3 to 3.3 times the diameter d1 of the upstream nozzle, and the diameter d2 of the downstream nozzle is 1.2 to 1.3 times the diameter d1 of the upstream nozzle; the main body of the self-excited oscillation cavity (5.9) is a cylinder The diameter of the cavity is 18 times the diameter of the upstream nozzle d1; the longitudinal section of the cavity is a parallelogram that is symmetrical up and down. The recess is downstream.