CN103742115B - A kind of coal mine underground fracturing sealing device and method - Google Patents

Abstract

A kind of coal mine underground fracturing sealing device and method, device comprises water injection pipe, return pipe, front and back polyurethane sealing of hole section, safety valve, umbrella-type bracing or strutting arrangement assembly, Grouting Pipe.Umbrella-type bracing or strutting arrangement assembly is made up of umbrella-type support frame, stay pipe, slip hoop, piston rod, piston, wherein stay pipe is provided with guide-track groove, safety valve, and when boring sent into by umbrella-type sealing device, device is contraction-like, is convenient to device and sends into boring.When injection initial pressure is the water under high pressure of 5MPa, umbrella-type bracing or strutting arrangement is opened, and is pushed away forward by piston, umbrella-type support frame struts, be punctured in coal body, water under high pressure constantly extrudes sealing of hole section, thus it is darker to make umbrella-type support frame thrust coal body, when water injection pressure be increased to >=15MPa time, press water breaks through safety valve, implements fracturing work, substantially increase sealing of hole section bearing capacity to boring, improve the pressure of water filling simultaneously, also improve fracturing effect.Its structure is simple, easy to operate, and bearing capacity is high, good sealing effect.

Description

A coal mine underground fracturing sealing device and method

technical field

The invention relates to a drilling sealing device and method, in particular to a sealing device and method suitable for underground coal mine fracturing.

Background technique

The geological conditions of my country's coal mines are complex, high-gas coal seams account for 50-70%, and high-gas low-permeability coal seams account for about 70% of them. The mining of high-gassy and low-permeability coal seams is often accompanied by a large amount of gas gushing, especially with the efficient intensification of coal production and the increase of mining depth, the amount of gas gushing is increasing, and the threat of gas explosion and gas outburst is also increasing. Gas disasters have become the most important factor restricting the development of intensive mining technology and safe production in colleges and universities. Therefore, how to solve the problem of gas gushing in the process of mining high-gas coal seams is of great significance to the safe production of coal mines.

In order to prevent and control mine gas, the first problem to be solved is how to improve the air permeability of low-permeability coal seams. For this reason, coal mines often adopt technologies such as underground coal seam high hydraulic fracturing and deep space loosening blasting to relieve pressure and increase permeability of coal. The formation of cracks in the body improves the air permeability of the coal seam. One of the technical difficulties is the high-pressure sealing of boreholes. For example, when high hydraulic fracturing is performed on coal seams, in order to form an effective fracture network inside the coal, for coal seams buried at a depth of 1000m, the sealing ability of boreholes needs to withstand water pressure above 30MPa. Otherwise, water leakage will occur in the borehole and affect the fracturing effect. In order to ensure the quality and success rate of hydraulic fracturing, it is imperative to develop high-pressure drilling sealing equipment.

Contents of the invention

Technical problem: The purpose of the present invention is to overcome the deficiencies in the prior art and provide a coal mine underground fracturing sealing device with simple structure, high pressure bearing capacity and good sealing effect.

Technical solution: The coal mine underground fracturing sealing device of the present invention includes a water injection pipe, a grout return pipe and a grout injection pipe fixed in the borehole through a polyurethane sealing section, wherein the water injection pipe passes through the front and rear polyurethane sealing sections, and the grout return The pipe and the grouting pipe enter the space formed by the front and rear polyurethane sealing sections and the drilling. The grout return pipe entering the sealing space is longer than the grouting pipe entering the sealing space. The pipe wall at the front of the water injection pipe A plurality of safety valves are arranged at intervals around the water injection pipe. The front end of the water injection pipe is equipped with an umbrella support device. The umbrella support device includes an umbrella support frame, a support tube, a sliding hoop, a piston rod, and a piston. The front part of the outer strut is hinged on the support tube, the inner strut of the umbrella support frame is hinged on the sliding hoop, the sliding hoop is connected to the piston that can move forward inside the support tube through the piston rod, and the sliding hoop is connected to the support tube. The matching pipe sections are symmetrically provided with guide rail grooves which can make the sliding hoop move forward.

The sliding hoop includes an outer sleeve sleeved on the support tube, the outer sleeve is provided with an inner sleeve for fixing the piston rod, and the two sides of the inner sleeve and the outer sleeve are connected with connecting blocks that can move in the guide rail groove of the support tube; The two ends of the piston rod are respectively threadedly connected with the inner casing of the piston and the support pipe; the front part of the pipe section where the sliding hoop matches the support pipe is provided with an elastic support card that prevents the sliding hoop from retreating; the pressure of the safety valve Set to 6MPa.

The coal mine underground fracturing sealing method using the above-mentioned device comprises the following steps:

(a) Drilling. Drilling is carried out according to the drilling orientation designed in the construction plan, and the drilling depth is set to the coal wall;

(b) Assemble the device, install the umbrella support device at the front end of the water injection pipe, connect the umbrella support frame of the umbrella support device to the support pipe, connect the sliding hoop and the piston thread together through the piston rod, and then connect the sliding hoop Set on the support tube through the guide rail groove, at this time, the umbrella-shaped support frame is in a contracted state;

(c) Send the pipe, bind the polyurethane sealing tape on the water injection pipe with a safety valve at the front, then send the water injection pipe into the drill hole until it reaches the set position, then send the grouting pipe and the grout return pipe into the In the borehole, at the same time, bind the polyurethane sealing tape at the section where the water injection pipe, grouting pipe and grout return pipe enter the borehole to block the borehole opening;

(d) Grouting, inject cement slurry into the drilled holes blocked by the front and rear polyurethane sealing sections through the grouting pump, and when the slurry flows out of the grouting pipe, close the valve on the grouting pipe, continue grouting for 1 to 2 minutes and then close it The grouting pump completes the plugging of the front and rear polyurethane sealing sections to plug the borehole;

(e) Water injection, set the initial pressure of water to 5MPa, and inject high-pressure water with a pressure of 5MPa into the borehole through the water injection pipe through the water injection pump. The sliding hoop connected to the piston rod moves forward, and the umbrella-shaped support frame hinged on the sliding hoop is stretched out and pierced into the coal body. With the continuous injection of high-pressure water, the pressure of high-pressure water continuously squeezes the front and rear polyurethane sealing sections, thereby The deeper the umbrella-shaped support frame penetrates into the coal body;

(f) For fracturing, increase the water injection pressure until the final water injection pressure is ≥15MPa. When the water injection pressure exceeds the 6MPa pressure set by the safety valve, the safety valve will be flushed open, and high-pressure water will be sprayed from the inlet of the safety valve into the borehole. Carry out fracturing operations on boreholes.

Beneficial effects: the sealing device provided by the present invention has the effect of a mechanical seal. When the umbrella seal device is sent into the borehole, the device is in a contracted shape, which is convenient for the device to be sent into the borehole. In the opening stage of the device, the water pressure is not enough to open the safety valve, but the piston can be pushed to the left, so that the sliding hoop moves to the left, and the device is opened under the push of the sliding hoop. There is a non-return groove on the support pipe, which can prevent the high-pressure water from pushing the pipe hoop away, thereby avoiding the shrinkage of the umbrella-shaped support frame. When high-pressure water is injected into the borehole, the high-pressure water will squeeze the sealing section, so that the umbrella-shaped support frame can penetrate deeper into the coal body, improve the pressure bearing capacity of the sealing section, and then increase the pressure of water injection , improve the fracturing effect.

Advantages: The fracturing sealing device provided by the present invention has a simple structure, and the mechanical seal is used to improve the pressure bearing capacity of the sealing section, which essentially improves the safety of the device without increasing the length of the sealing section, thus reducing the material usage, reducing costs.

Description of drawings

Fig. 1 is a structural diagram of the present invention.

Figure 2 is a structural diagram of the support tube.

In the figure: 1. Water injection pipe; 2. Coal body; 3. Slurry return pipe; 4. Front and rear polyurethane sealing sections; 5. Safety valve; 6. Umbrella support device assembly; 6-1. Umbrella support frame; 6-2, support pipe; 6-3, sliding hoop; 6-4, piston rod; 6-5, piston; 7, drilling; 8, grouting pipe.

detailed description

An embodiment of the present invention will be further described below in conjunction with accompanying drawing:

As shown in Figure 1, the coal mine underground fracturing sealing device of the present invention is mainly composed of a water injection pipe 1, a grout return pipe 3, a front and rear polyurethane sealing section 4, a safety valve 5, an umbrella support device 6, and a grouting pipe 8. The water injection pipe 1, the grout return pipe 3 and the grout injection pipe 8 are fixed in the borehole 7 through the polyurethane sealing section, wherein the water injection pipe 1 passes through the front and rear polyurethane sealing sections 4, and the grout return pipe 3 and the grout injection pipe 8 enter the In the space formed by the front and rear polyurethane sealing sections 4 sealing and drilling, the grout return pipe 3 entering the sealing space is long, the grouting pipe 8 entering the sealing space is short, and the pipe wall around the front part of the water injection pipe 1 A plurality of safety valves 5 are arranged at intervals, and the front end of the water injection pipe 1 is set with an umbrella support device 6, and the umbrella support device 6 includes an umbrella support frame 6-1, a support pipe 6-2, and a sliding hoop 6-3 , piston rod 6-4, piston 6-5, wherein, the front part of the outer strut of umbrella-shaped support frame 6-1 is hinged on the support tube 6-2, and the inner strut of umbrella-shaped support frame 6-1 is hinged on the slide On the hoop 6-3, the sliding hoop 6-3 is connected to the piston 6-5 that can move forward inside the support tube 6-2 through the piston rod 6-4, and the sliding hoop 6-3 is matched with the support tube 6-2 Symmetrically have a guide rail groove that can make the sliding hoop 6-3 move forward on the pipe section. The two ends of the piston rod 6-4 are respectively threadedly connected with the inner casing of the piston 6-5 and the support pipe 6-2; There is an elastic support card that blocks the sliding hoop 6-3 from retreating. The elastic support card is similar to the umbrella support card. It is composed of a spring and a block embedded in the wall of the support tube 6-2. When the sliding hoop 6-3 moves forward to When supporting the front of the card, the elastic supporting card pops up to block the sliding hoop 6-3. The pressure of the safety valve 5 is set to 6MPa.

As shown in Figure 2, the sliding hoop 6-3 includes an outer sleeve sleeved on the support tube 6-2, the outer sleeve is provided with an inner sleeve for fixing the piston rod 6-4, and the inner sleeve is connected to both sides of the outer sleeve. There is a connecting block movable in the support pipe 6-2 guide rail groove.

Underground coal mine fracturing sealing method of the present invention, concrete steps are as follows:

(a) Drilling. Drilling is carried out according to the drilling orientation designed in the construction plan. Taking parallel holes as an example, drilling a specified depth of drilling is perpendicular to the coal wall;

(b) Assembling the device, put the umbrella support device 6 on the front end of the water injection pipe 1, connect the umbrella support frame 6-1 of the umbrella support device 6 to the support pipe 6-2, and slide it through the piston rod 6-4. The hoop 6-3 and the piston 6-5 are threaded together, and then the sliding hoop 6-3 is set on the support pipe 6-2 through the guide rail groove, and at this time, the umbrella support frame 6-1 is in a contracted state;

(c) Send the pipe, bind the polyurethane sealing tape on the water injection pipe 1 with the safety valve 5 at the front, then send the water injection pipe 1 into the drill hole 7 until it reaches the set position, and then put the grouting pipe 8 and The grout return pipe 3 is sent into the borehole, and at the same time, the polyurethane sealing tape is bound at the section where the water injection pipe 1, the grout injection pipe 8 and the grout return pipe 3 enter the borehole to block the hole of the borehole; the grout return pipe 3 is located at Above the water injection pipe 1, the grouting pipe 8 is positioned at the bottom of the water injection pipe 1, and the grout return pipe 3 entrance goes deep into the hole bottom of the plugging borehole, and the grouting pipe 8 entrance enters the plugging borehole, and the grout return pipe 3 is relatively The grouting pipe 8 is long, and the grouting pipe 3 is short relative to the grouting pipe 8;

(d) Grouting: inject cement slurry into the drill holes blocked by the front and rear polyurethane sealing sections 4 through the grouting pump, and when the grout flows out of the grout return pipe 3, close the valve on the grout return pipe 3 and continue grouting 1 Turn off the grouting pump after ~2 minutes, and complete the plugging of the front and rear polyurethane sealing sections 4 to plug the borehole;

(e) Water injection, set the initial pressure water to 5MPa, and inject high-pressure water with a pressure of 5MPa into the borehole through the water injection pipe 1 through the water injection pump. Since the pressure water at this time is lower than the 6MPa pressure set by the safety valve 5, it is safe The valve 5 will not be opened, and under the action of 5MPa high-pressure water, the piston 6-5 in the support pipe 6-2 is pushed forward, driving the sliding hoop 6-3 connected with the piston rod 6-4 to move forward, hinged The umbrella-shaped support frame 6-1 on the sliding hoop 6-3 is stretched and pierced into the coal body. With the continuous injection of high-pressure water, the pressure of the high-pressure water continuously squeezes the front and rear polyurethane sealing sections 4, so that the umbrella-shaped support The deeper the frame 6-1 penetrates into the coal body, the elastic support card provided at the front of the pipe section where the sliding hoop 6-3 matches the support pipe 6-2 will pop out, preventing the sliding hoop 6-3 from retreating, and improving the bearing capacity of the sealing section. Pressure capacity, which in turn can increase the pressure of water injection and improve the fracturing effect;

(f) Carry out hydraulic fracturing on the borehole and increase the water injection pressure until the final water injection pressure is ≥ 15MPa. When the water injection pressure exceeds the 6MPa pressure set by the safety valve 5, the safety valve 5 will be opened, and the high-pressure water will flow from the safety valve 5. The inlet spray enters the borehole and performs fracturing operations on the borehole.

Claims (6)

1. a coal mine underground fracturing sealing device, comprise the water injection pipe (1) be fixed on through polyurethane sealing of hole section in boring, return pipe (3) and Grouting Pipe (8), wherein, water injection pipe (1) is through front and back polyurethane sealing of hole section (4), return pipe (3) and Grouting Pipe (8) enter by front and back polyurethane sealing of hole section (4) shutoff with hole in the space that formed, the return pipe (3) entering shutoff space is long, the Grouting Pipe (8) entering shutoff space is short, it is characterized in that: the tube wall ambient separation of described water injection pipe (1) front portion is provided with multiple safety valve (5), the front end sleeve of water injection pipe (1) is equipped with umbrella-type bracing or strutting arrangement (6), described umbrella-type bracing or strutting arrangement (6) comprises umbrella-type support frame (6-1), stay pipe (6-2), slide hoop (6-3), piston rod (6-4), piston (6-5), wherein, the outer strut front portion of umbrella-type support frame (6-1) is hinged on stay pipe (6-2), the internal overarm support of umbrella-type support frame (6-1) is hinged on and slides on hoop (6-3), the hoop (6-3) that slides connects the piston (6-5) that can move forward in stay pipe (6-2) inside through piston rod (6-4), on the pipeline section that the described hoop (6-3) that slides matches with stay pipe (6-2), symmetry has the guide-track groove that slip hoop (6-3) can be made to move forward.

2. a kind of coal mine underground fracturing sealing device according to claim 1, it is characterized in that: described slip hoop (6-3) comprises the outer tube be sleeved on stay pipe (6-2), be provided with the inner sleeve of fixed piston rod (6-4) in outer tube, inner sleeve and outer tube both sides are connected with can the contiguous block of movement in stay pipe (6-2) guide-track groove.

3. a kind of coal mine underground fracturing sealing device according to claim 1, is characterized in that: described piston rod (6-4) one end is threaded with piston (6-5), and the other end is threaded with the inner sleeve with stay pipe (6-2).

4. a kind of coal mine underground fracturing sealing device according to claim 1, is characterized in that: the pipeline section front portion that described slip hoop (6-3) matches with stay pipe (6-2) is provided with that stopping slides binds round the resiliency supported card that (6-3) retreat.

5. a kind of coal mine underground fracturing sealing device according to claim 1, is characterized in that: the pressure setting of described safety valve (5) is 6MPa.

6. use the coal mine underground fracturing encapsulating method of device described in claim 1, it is characterized in that, comprise the steps:

A () is drilled, the bore direction according to Construction Scheme is drilled, to the boring of rib set depth;

B () device is assembled, in the front end of water injection pipe (1) suit umbrella-type bracing or strutting arrangement (6), the umbrella-type support frame (6-1) of umbrella-type bracing or strutting arrangement (6) is connected on stay pipe (6-2), by piston rod (6-4), slip hoop (6-3) and piston (6-5) are threaded togather, again slip hoop (6-3) is sleeved on stay pipe (6-2) by guide-track groove, now, umbrella-type support frame (6-1) is in contraction state;

C () send pipe, the upper colligation polyurethane sealing pore area of the water injection pipe (1) of safety valve (5) is housed in front portion, afterwards water injection pipe (1) is sent in boring (7), until desired location, again Grouting Pipe (8) and return pipe (3) are sent in boring, enter boring section colligation polyurethane sealing pore area at water injection pipe (1), Grouting Pipe (8) and return pipe (3) simultaneously, drilling orifice is blocked;

(d) slip casting, by grouting pump, cement grout is injected in the boring of front and back polyurethane sealing of hole section (4) shutoff, when waiing upon outflow slurries in return pipe (3), close the valve on return pipe (3), close grouting pump after continuing slip casting 1 ~ 2min, complete the shutoff in polyurethane sealing of hole section (4) the shutoff boring of front and back;

(e) water filling, setting initial pressure water is 5MPa, be that the water under high pressure of 5MPa is by water injection pipe (1) injection hole by water injecting pump by pressure, under the effect of 5MPa water under high pressure, piston (6-5) in stay pipe (6-2) is passed forward, the slip hoop (6-3) be connected with piston rod (6-4) is driven to move forward, be hinged on the umbrella-type support frame (6-1) slided on hoop (6-3) to strut, be punctured in coal body, along with water under high pressure constantly injects, the pressure of water under high pressure constantly extrudes front and back polyurethane sealing of hole section (4), thus it is darker to make umbrella-type support frame (6-1) thrust coal body,

F () pressure break, improves the pressure of water filling, until last water injection pressure >=15MPa, when water injection pressure exceedes the 6MPa pressure that safety valve (5) sets, safety valve (5) is rushed to open, and water under high pressure enters boring from the entrance ejection of safety valve (5), implements fracturing work to boring.