Waste shaft gushing water and grouting isolation method

Abstract

The invention relates to a waste shaft gushing water grouting isolation method, and belongs to the field of mine water disaster treatment. According to the technical scheme, geological conditions and current situations of the abandoned wellbore are investigated and detected; drilling is conducted on the outer side of the shaft, the drilling hole is away from the edge of the shaft by a certain distance, a directional drilling technology is used, drilling is conducted in the shaft at a certain depth, and geological and hydrological conditions are further detected in the drilling process; a water blocking plug with a certain thickness is constructed in a shaft by drilling and injecting cement paste, and water in a water-bearing layer is prevented from entering the lower portion of the shaft. The method has the advantages that the water blocking plug is built in the abandoned shaft through drilling and grouting, the purpose of preventing water in a water-bearing layer from entering the lower portion of the shaft is achieved, the construction technology is simple, investment is small, the water blocking effect is good, and safety is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of mine water hazard control, and in particular to a method for isolating water inrush in abandoned mine shafts by grouting. Background Technology

[0002] Water hazards are one of the major disasters threatening safe production in coal mines. Water accumulation in old mine shafts is a major source of these hazards, and controlling this water accumulation is a crucial aspect of coal mine water control. my country has a long history of coal mining, and many small coal mines exist in shallow coal seams. Some of these small mines were not sealed after closure, and some abandoned mine shafts even connected to aquifers, threatening the safe mining of deeper coal mines. In one case, a partially collapsed abandoned mine shaft connected to an aquifer, with the water level at a depth of 24.5 meters. Pumps were used to extract water from this shaft, but the pumps could only reach a depth of 50 meters. The lower part of the shaft was filled with debris, and the pumping capacity reached 150 cubic meters. 3 A hissing sound was heard coming from the well casing. A drilling rig was dispatched to probe the casing, encountering filling material at a depth of 51m, making further drilling extremely difficult. The deepest point reached was 59m. Retrieved items included plastic ventilation duct fabric, wood chips, cement-bonded red bricks (the well casing was constructed of red bricks), and quartz sandstone pebbles with diameters of several centimeters. Analysis suggests that the well casing had collapsed and become blocked due to long-term abandonment, with the accumulated water source originating from the alluvial gravel layer. Given that further drilling was impossible and conventional well casing filling methods were not feasible, this invention proposes a method for isolating water seepage in abandoned well casings using grouting. Summary of the Invention

[0003] This invention addresses the specific situation where abandoned wells have collapsed but have not been properly filled, still allowing aquifer water to flow through and threatening deep mines, making conventional well filling methods impractical. It provides a method for isolating water inflow through abandoned wells by grouting.

[0004] The technical solution adopted in this invention is as follows: Investigate and explore the geological conditions and current status of abandoned well casings; drill holes on the outside of the well casing, a certain distance from the edge of the well casing, using directional drilling technology to drill into the well casing at a certain depth, further exploring geological and hydrological conditions during the drilling process; inject cement grout into the drill holes to construct a water-blocking plug of a certain thickness in the well casing, preventing aquifer water from entering the lower part of the well casing. Specific steps are as follows:

[0005] 1. Investigate the depth of abandoned wells, the geological conditions they pass through, observe the collapse of the well walls, and detect the filling and water accumulation in the wells.

[0006] 2. Drill holes outside the wellbore, at a certain distance from the edge of the wellbore. The diameter of the borehole must meet the minimum requirements for processes such as isolating alluvial layers, directional drilling, and grouting. Determine the thickness of the alluvial layer. Lower the grouting casing into the stable bedrock. Use directional drilling technology to drill into the wellbore. Further explore the geological and hydrological conditions during the drilling process.

[0007] 3. By intermittently injecting cement slurry through drilling, observe the changes in water level in the wellbore and the upward flow of cement slurry until the grouting pressure reaches the final pressure requirement, forming a water-blocking plug in the wellbore to achieve the goal of isolating the aquifer water.

[0008] The beneficial effects of this invention are as follows: by drilling and grouting, a water-blocking plug is constructed in the abandoned well casing, thereby isolating the aquifer water from entering the lower part of the well casing. The construction process is simple, the investment is low, the water-blocking effect is good, and the safety is guaranteed. Attached Figure Description

[0009] To more clearly illustrate the technical solution of the present invention, the accompanying drawings will be briefly described below.

[0010] Figure 1 This is a schematic diagram of the construction of drilling and grouting to isolate the aquifer of abandoned wells in a specific embodiment of the present invention.

[0011] Figure 2 This is a schematic diagram of the wellbore after grouting to form a water-blocking plug, according to a specific embodiment of the present invention.

[0012] In the diagram: 1. Well shaft, 2. Water level in the well shaft, 3. Filling material, 4. Collapsed cavity in the well wall, 5. Drilling equipment, 6. Borehole, 7. Water-blocking plug. Detailed Implementation

[0013] 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:

[0014] 1. Investigate the depth of the abandoned well, the geological strata it penetrates, observe the well wall collapse, and detect the well filling and water accumulation. The investigation revealed a well diameter of 2.6 m, a depth of 225.86 m, and a water level depth of 24.5 m. Pumping water from this well only reached a depth of 50 m, as the lower part was filled with debris. The pumping capacity reached 150 m³ / h. 3 A hissing sound was heard coming from the well shaft. A drilling rig was dispatched to probe the shaft, encountering filling material at a depth of 51m, making further drilling extremely difficult. The deepest point reached was 59m. Objects retrieved included plastic ventilation duct fabric, wood chips, cement-bonded red bricks (the well shaft was constructed of red bricks), and quartz sandstone pebbles with diameters of several centimeters. Analysis suggests that the well shaft had collapsed and become blocked due to long-term abandonment, with the accumulated water originating from the alluvial gravel layer.

[0015] 2. Drilling was conducted on the outside of the wellbore using directional drilling technology to penetrate into the wellbore. During drilling, geological and hydrological conditions were further investigated. Due to site limitations, the borehole was positioned 140° southeast of the wellbore, 2.9m from the well wall. The borehole opening was through a backfill layer of gangue, followed by loess and gravel. A cavity was encountered at 22-27m, and a 273mm casing was run down to 29.9m. Bedrock was encountered at 76.2m, and a 159mm casing was run down to 76.31m. Directional drilling then commenced, and red bricks were encountered at 127m, allowing entry into the wellbore. Drilling continued to 136.18m, where the rock was relatively soft and no water leakage was observed. The wellbore filling was identified as red brick blocks, gray and purple mudstone, and grayish-white sandstone. The drilling revealed that the water accumulation in the wellbore originated from an alluvial gravel aquifer; the wellbore collapse and blockage occurred from a depth of 51m to below 136.18m.

[0016] 3. By injecting cement grout into the borehole, a water-blocking plug is formed in the wellbore, achieving the goal of isolating the aquifer water. Grouting is carried out intermittently once a day, with each injection being 20-30 tons, and a water-cement ratio of 0.75-0.6:1. After grouting, the borehole is swept back to its original depth. When a total of 191 tons of grout has been injected, the water level in the wellbore rises by 1.0 m, the probed wellbore depth is 24.60 m, and the initial wellbore depth is 51 m, forming a 26.4 m thick cement water-blocking column. When a total of 211 tons of cement has been injected, grout returns to the borehole opening, and the grouting borehole maintains a pressure of 0.2-0.4 MPa. When a total of 336 tons of cement has been injected, the grouting pressure reaches 0.45 MPa, and grouting continues until a total of 358 tons of grout has been injected. After sweeping the borehole, the pressure at the water outlet reaches 2 MPa, at which point grouting is completed and the borehole is sealed. Analysis shows that the wellbore from 24.60m to 136.18m has been compacted, and the gravel aquifer has been isolated from the lower wellbore.

[0017] The beneficial effects of this invention are as follows: by drilling and grouting, a water-blocking plug is constructed in the abandoned well casing, thereby isolating the aquifer water from entering the lower part of the well casing. The construction process is simple, the investment is low, the water-blocking effect is good, and the safety is guaranteed.

Claims

1. A method for isolating water inrush in abandoned wells using grouting. The technical solution is as follows: investigate and explore the geological conditions and current status of the abandoned well; drill holes on the outside of the well, a certain distance away from the edge of the well, using directional drilling technology to drill into the well at a certain depth, and further explore the geological and hydrological conditions during the drilling process; intermittently inject cement grout through the drill holes to construct a water-blocking plug of a certain thickness in the well, thereby preventing the aquifer water from entering the lower part of the well.

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