Underground under-pressure hydrological observation borehole casing dislocation repairing method

Abstract

The invention relates to an underground hydrological observation borehole casing dislocation repairing method under pressure, and belongs to the field of mine hydrological monitoring and water disaster treatment. According to the technical scheme, the method comprises the steps that the dislocation depth and the dislocation condition of the casing pipes are detected, a new casing pipe with a proper caliber is put in, annular gaps between the new casing pipe and the old casing pipe are filled through grouting, and rock stratum fractures at the dislocation position and fractures generated by roadway floor heaving are subjected to grouting reinforcement. The method has the beneficial effects that the dislocation depth and the staggering degree of the original casing pipe of the drill hole are accurately and visually determined; the caliber and depth of the new casing pipe are matched with the damage condition of the original casing pipe; the grouting process can reduce grout loss and guarantee the grouting effect; hole sweeping is not needed after grouting, and the process is simple; and the service life is prolonged through roadway grouting reinforcement.

Description

Technical Field

[0001] This invention relates to the field of mine hydrological monitoring and water hazard control, and in particular to a method for repairing misaligned casing in pressurized underground hydrological observation boreholes. Background Technology

[0002] Mine hydrological observation boreholes often serve the entire lifespan of a mine. Due to the special underground environmental conditions, factors such as ground stress, mining stress, water pressure, and corrosion can easily cause deformation and bulging around the borehole, leading to casing misalignment, affecting normal use, and even causing water damage. Furthermore, the location and degree of casing misalignment are difficult to determine accurately, and borehole repair work is also limited by underground conditions, making it difficult to lower the repair inner casing and resulting in poor grouting and water plugging effects. Summary of the Invention

[0003] This invention addresses the problems of difficulty in accurately determining the location and degree of misalignment of casing in downhole pressurized hydrological observation boreholes, difficulties in running down repair casing, and poor grouting and water plugging effects by providing a method for repairing misaligned casing in downhole pressurized hydrological observation boreholes.

[0004] The technical solution adopted in this invention is as follows: Detect the location and distance of the casing misalignment, insert a new casing of appropriate diameter, grout to fill the annular gap between the old and new casings, and reinforce the rock fissures at the misalignment point and the fissures caused by the tunnel floor heave with grout. The specific steps are as follows:

[0005] 1. Use downhole drilling video technology to detect the location and distance of casing misalignment.

[0006] 2. Use a brushing device to remove rust and scale from the inner wall of the casing.

[0007] 3. Based on the casing misalignment distance, select the diameter of the new casing through testing, and install the new casing with a guide at the bottom, hemp or water-swellable tape wrapped at the lower end, and a grouting device at the upper end. Connect the new casing to the original casing through a flange. The new casing should be installed to a depth that exceeds the misalignment depth by a certain distance.

[0008] 4. Use a grouting pump to inject cement grout to fill the annular gap between the old and new casings, and to fill the rock fissures caused by the misalignment of the original casing and the rock fissures caused by the heave of the roadway floor.

[0009] 5. Grouting reinforcement of the area affected by the bottom heave around the borehole.

[0010] The beneficial effects of this invention are: accurately and intuitively determining the misalignment depth and degree of the original casing in the borehole; matching the diameter and depth of the new casing with the damage condition of the original casing; reducing grout loss and ensuring grouting effect through the grouting process; eliminating the need for hole sweeping after grouting, simplifying the process; and extending the service life of the roadway through grouting reinforcement. Attached Figure Description

[0011] To more clearly illustrate the technical solution of the present invention, the accompanying drawings will be briefly described below.

[0012] Figure 1 This is a schematic diagram of the original casing being misaligned in a specific embodiment of the present invention.

[0013] Figure 2 This is a schematic diagram of the process of inserting a new casing and grouting in a specific embodiment of the present invention.

[0014] Figure 3 This is a schematic diagram of drilling after casing misalignment repair in a specific embodiment of the present invention.

[0015] In the diagram: 1. Original casing, 2. New casing, 3. Misalignment, 4. Water blocking device, 5. Steel pipe section with the same diameter as the original casing, 6. New casing section, 7. Flange, 8. Grouting gate valve, 9. Drainage gate valve, 10. Grouting pump, 11. Pressure gauge, 12. High-pressure valve, 13. Rock fissure. Detailed Implementation

[0016] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. The specific steps are as follows:

[0017] 1. Review the drilling data of the pressurized hydrological observation borehole and install drainage facilities with appropriate capacity according to the water inflow during borehole formation to ensure drainage for borehole inspection and treatment.

[0018] 2. Use a downhole drilling video surveying instrument to detect the misalignment of the original casing 1 and determine the misalignment depth and distance.

[0019] 3. Use a brushing device to remove rust and scale from the inner wall of the original sleeve 1.

[0020] 4. Select a new casing 2, 10 meters in total length and one diameter smaller than the original casing 1, and tentatively lower it into the original casing 1 to see if it can pass through the misalignment point 3. The bottom end of the new casing 2 can be equipped with a guide to facilitate smooth passage through the misalignment point 3. If even with a guide, it cannot pass through the misalignment point 3, the upper end of the casing below the misalignment point 3 needs to be straightened and cleaned. If the original casing 1 has a large misalignment distance, making it difficult to lower a new casing 2 that is one diameter smaller than the original casing 1, try lowering a new casing 2 that is two diameters smaller than the original casing 1. After testing... The diameter of the new casing 2 is determined by inspection; the new casing 2 is lowered to a depth more than 10 meters beyond the misalignment point 3, and the bottom end is equipped with a guide to facilitate passage through the misalignment point 3. A water-blocking device 4 is installed 1-2 meters above the bottom end, which is generally wrapped with hemp or water-swellable tape to block water and grout. The upper part of the new casing 2 is equipped with a grouting device, including a steel pipe short section 5 with the same diameter as the original casing, a new casing short section 6, upper and lower flanges 7, a grouting gate valve 8, and a drain gate valve 9; the new casing 2 is connected to the original casing 1 through the flange 7.

[0021] 5. Use grouting pump 10 to inject cement grout to fill the annular gap between the old and new casings, and to fill the rock fissures 13 caused by the misalignment of the original casing and the heave at the bottom of the tunnel. During grouting, open the high-pressure valve 12 to draw water out of the aquifer, reducing the water pressure at the misalignment of the original casing 3 and the water inflow at the bottom of the tunnel. This allows the cement grout to first sink and accumulate on the water-blocking device 4 under gravity, gradually filling the annular gap between the old and new casings between the water-blocking device and the misalignment. Then, it fills the rock fissures 13 caused by the misalignment of the original casing 3 and the heave at the bottom of the tunnel. Finally, it fills the annular gap between the old and new casings between the misalignment of the original casing and the grouting gate valve. Grouting is done intermittently. If grout leaks at the bottom of the tunnel or a large amount of water with grout flows in at the high-pressure valve, grouting is stopped and resumed after an interval of 1-2 hours. The final grouting pressure reaches the water pressure of the observed borehole.

[0022] 6. Grouting reinforcement of the borehole is carried out in the roadway surrounding the borehole, with the depth exceeding the original casing misalignment depth.

[0023] The beneficial effects of this invention are: accurately and intuitively determining the misalignment depth and degree of the original casing in the borehole; matching the diameter and depth of the new casing with the damage condition of the original casing; reducing grout loss and ensuring grouting effect through the grouting process; eliminating the need for hole sweeping after grouting, simplifying the process; and extending the service life of the roadway through grouting reinforcement.

Claims

1. A method for repairing a broken downhole casing under pressure, comprising detecting the depth and condition of the casing break, lowering a new casing of appropriate diameter, grouting the annular gap between the new and old casings, and grouting the fractures in the rock strata and fractures caused by the floor heave of the roadway.

2. Using downhole drilling video technology to detect the depth and condition of the casing break.

3. Using a hole cleaning device to remove rust and scale from the inner wall of the casing.

4. According to the distance of the casing break, select the diameter of the new casing by testing, and lower the new casing with a guide at the bottom, a hemp or water-swellable adhesive tape at the lower end, and a grouting device at the upper end, connected to the original casing through flanges, and the depth of the new casing exceeds the break depth by a certain distance.

5. A grouting device comprising a double-layer casing, upper and lower flanges, a grouting gate valve, and a water discharge gate valve.

6. A grouting process using a grouting pump to inject cement slurry, gradually filling the annular gap between the new and old casings below the original casing break, the fractures in the rock strata at the original casing break, the fractures in the rock strata caused by the floor heave of the roadway, and the annular gap between the new and old casings above the original casing break.

7. Grouting and reinforcing the area affected by the floor heave around the borehole.

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