CA3052021A1 - Water retention method for promoting self-healing of mining fractures by chemically softening carbonatite - Google Patents
Water retention method for promoting self-healing of mining fractures by chemically softening carbonatiteInfo
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- CA3052021A1 CA3052021A1 CA3052021A CA3052021A CA3052021A1 CA 3052021 A1 CA3052021 A1 CA 3052021A1 CA 3052021 A CA3052021 A CA 3052021A CA 3052021 A CA3052021 A CA 3052021A CA 3052021 A1 CA3052021 A1 CA 3052021A1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/38—Waterproofing; Heat insulating; Soundproofing; Electric insulating
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/001—Improving soil or rock, e.g. by freezing; Injections
- E21D9/002—Injection methods characterised by the chemical composition used
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Abstract
The present invention discloses a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite, which is suitable for the technical fields of water resource protection and mine water hazard prevention and treatment in coal mining. Information of the distribution range of a water-conducting fractured zone in overlying strata that communicates with a water-bearing layer in stratum and information of a rock stratum with rich carbonatite mineral in a mining area are determined; in the mining area, a drill hole is constructed from the ground surface to a target rock stratum with rich carbonatite mineral within the range of the water-conducting fractured zone and below the water-bearing layer in stratum, a softener is injected to the fractures in the target rock stratum through the drill hole, to fully react with the carbonatite mineral in the target rock stratum to soften the carbonatite, so as to drive the tension fractures in the rock mass to close gradually under the action of the stress in the mining stratum, to decrease the water conducting ability of the tension fractures, and thereby to artificially promote self-healing of the mining fractures and realize protection of the underground water-bearing layer.
The method has simple steps, can attain a reliable effect, and is highly practical.
The method has simple steps, can attain a reliable effect, and is highly practical.
Description
Description Water Retention Method for Promoting Self-Healing of Mining Fractures by Chemically Softening Carbonatite I. Technical Field The present invention relates to a water retention method, particularly to a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite applicable to the technical field of water resource protection and mine water hazard prevention and control in coal mining.
Background Art The underground coal mining may result in displacement and damage of the overlying strata, and thereby result in formation of mining fractures in the overlying strata; the mining fractures formed in the overlying strata provide channels for regional water resource loss, and become geological sources of ecological environment damages in mining area. Viewed from the general distribution characteristics of the mining-induced water-conducting fractured zone in the overlying strata, 3 zones are distributed in the vertical section within the "saddle-shaped" development range of the water-conducting fractured zone: a compression fractured zone, a tension fractured zone, and a central compaction zone. Wherein, the fractures in the compression fractured zone and the central compaction zone have smaller opening and lower overflow capacity, while the fractures in the tension fractured zone near the inner side of the mining boundary have larger developed opening and stronger overflow capacity; therefore, when the water-conducting fractured zone caused by coal mining communicates with the water-bearing layer in stratum, the main channels for water resource loss are the mining fractures with large openings in the tension fractured zone. Hence, the key to realize water resource protection in coal mining is to reasonably control the overflow capacity of the mining fractures in the tension fractured zone in the water-conducting fractured zone, so decreasing the opening of the mining fractures and promoting closing and self-healing of the mining fractures.
Rock strata with different lithology and strength exist in coal measure strata. Most of these rock strata are formed by carbonatite, alum inosilicate rocks, and a variety of clay minerals, and the difference in composition of various mineral components results in the difference in strength of various strata.
Relevant researches find that the mineral components in the rock mass often have long-time and persistent water-rock interactions with underground water, and thereby the bearing strength of the rock mass structures is weakened; in addition, the degree of strength weakening resulted from the water-rock interactions will be different, depending on the pH value of the underground water. The carbonatite mineral component in the rock mass is a substance that can easily react with acidic chemical substances. If the acidity of the underground water can be changed artificially to promote the softening effect of water-rock reaction in the rock strata, plastic flow will occur in the mining rock mass structures, and thereby the mining fractures in the rock mass can close gradually under the compaction action of the stress in the mining strata. That is undoubtedly an effective approach to decrease the overflow capacity of the mining fractures and promote self-healing of the mining fractures. Therefore, it is necessary to develop a special design of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite on the basis of the development characteristics of the mining-induced water-conducting fractured zone in the overlying strata.
Contents of the Invention Object of the Invention: to overcome the drawbacks in the prior art, the present invention provides a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite, in which by identifying the distribution area of a mining water-conducting fractured zone in the overlying strata that communicates with a water-bearing layer in stratum, a method of artificially injecting chemical softener to promote plastic flow of target rock stratum which is rich in carbonatite and promoteself-healing of the mining fractures is established, thereby reducing the water resource loss of the water-bearing layer, mitigating the threat of underground water hazard, and realizing green, safe and efficient production in the mine.
Technical Scheme: to achieve the above-mentioned object, a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention is provided, which comprises: according to the development characteristics of the water-conducting fractured zone in the mining overlying strata under specific mining conditions, determining the information of the distribution range of a water-conducting fractured zone in the overlying strata that communicates with a water-bearing layer in stratum in a mining area, and acquiring information of a rock stratum with rich carbonatite mineral at the same time; in the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, constructing a drill hole from the ground surface to a target rock stratum with rich carbonatite mineral which is in the water-conducting fractured zone and below the water-bearing layer in stratum; due to the distribution of a large quantity of fractures in the target rock stratum with rich carbonatite mineral, injecting a chemical softener to the fractures in the target rock stratum through the drill hole, and making the chemical softener to fully react with the carbonatite mineral in the target rock strata to promote softening of the rock mass structure of the carbonatite and gradually closing the tension fractures in the rock mass under the action of the stress in the mining stratum, to decrease the water conducting ability thereof, and thereby to realize artificially-promoted self-healing of the mining fractures and protection of the underground water-bearing layer.
The specific steps are as following:
a. judging the position of the water-bearing layer in stratum according to a geological borehole column above the mining area, and judging a coal mining area where the water-bearing layer in stratum is damaged by mining according to the height of the water-conducting fractured zone in the overlying strata at the same time; if the water-bearing layer exists within the range of the height of the water-conducting fractured zone, judging that the water-conducting fractured zone in the corresponding area communicates with the water-bearing layer and water-retention repair is required;
if there is no water-bearing layer within the range of the height of the water-conducting fractured zone, judging that water-retention repair is not required;
b. carrying out construction in the area requiring water-retention repair: in the mining area where the water-conducting fractured zone communicates with the water-bearing layer, sampling the rock strata within the range of the corresponding water-conducting fractured zone and below the water-bearing layer, testing the mineral components in the rock strata, and thereby determining the target rock stratum with rich carbonatite mineral;
c. constructing a softener injection drill hole downward in the ground surface corresponding to the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, wherein, the type of the drill hole is determined according to the construction conditions of the ground surface: if construction conditions for arranging a drilling field are available on the ground surface corresponding to the mining area, selecting a vertical drill hole in the ground surface;
otherwise, constructing a horizontal drill hole at a drilling field arranged at an appropriate position on the ground surface outside the mining area;
d. injecting a chemical softener that can easily react with the carbonatite mineral into the softener injection drill hole, and making the chemical softener to fully react with the carbonatite mineral in
Background Art The underground coal mining may result in displacement and damage of the overlying strata, and thereby result in formation of mining fractures in the overlying strata; the mining fractures formed in the overlying strata provide channels for regional water resource loss, and become geological sources of ecological environment damages in mining area. Viewed from the general distribution characteristics of the mining-induced water-conducting fractured zone in the overlying strata, 3 zones are distributed in the vertical section within the "saddle-shaped" development range of the water-conducting fractured zone: a compression fractured zone, a tension fractured zone, and a central compaction zone. Wherein, the fractures in the compression fractured zone and the central compaction zone have smaller opening and lower overflow capacity, while the fractures in the tension fractured zone near the inner side of the mining boundary have larger developed opening and stronger overflow capacity; therefore, when the water-conducting fractured zone caused by coal mining communicates with the water-bearing layer in stratum, the main channels for water resource loss are the mining fractures with large openings in the tension fractured zone. Hence, the key to realize water resource protection in coal mining is to reasonably control the overflow capacity of the mining fractures in the tension fractured zone in the water-conducting fractured zone, so decreasing the opening of the mining fractures and promoting closing and self-healing of the mining fractures.
Rock strata with different lithology and strength exist in coal measure strata. Most of these rock strata are formed by carbonatite, alum inosilicate rocks, and a variety of clay minerals, and the difference in composition of various mineral components results in the difference in strength of various strata.
Relevant researches find that the mineral components in the rock mass often have long-time and persistent water-rock interactions with underground water, and thereby the bearing strength of the rock mass structures is weakened; in addition, the degree of strength weakening resulted from the water-rock interactions will be different, depending on the pH value of the underground water. The carbonatite mineral component in the rock mass is a substance that can easily react with acidic chemical substances. If the acidity of the underground water can be changed artificially to promote the softening effect of water-rock reaction in the rock strata, plastic flow will occur in the mining rock mass structures, and thereby the mining fractures in the rock mass can close gradually under the compaction action of the stress in the mining strata. That is undoubtedly an effective approach to decrease the overflow capacity of the mining fractures and promote self-healing of the mining fractures. Therefore, it is necessary to develop a special design of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite on the basis of the development characteristics of the mining-induced water-conducting fractured zone in the overlying strata.
Contents of the Invention Object of the Invention: to overcome the drawbacks in the prior art, the present invention provides a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite, in which by identifying the distribution area of a mining water-conducting fractured zone in the overlying strata that communicates with a water-bearing layer in stratum, a method of artificially injecting chemical softener to promote plastic flow of target rock stratum which is rich in carbonatite and promoteself-healing of the mining fractures is established, thereby reducing the water resource loss of the water-bearing layer, mitigating the threat of underground water hazard, and realizing green, safe and efficient production in the mine.
Technical Scheme: to achieve the above-mentioned object, a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention is provided, which comprises: according to the development characteristics of the water-conducting fractured zone in the mining overlying strata under specific mining conditions, determining the information of the distribution range of a water-conducting fractured zone in the overlying strata that communicates with a water-bearing layer in stratum in a mining area, and acquiring information of a rock stratum with rich carbonatite mineral at the same time; in the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, constructing a drill hole from the ground surface to a target rock stratum with rich carbonatite mineral which is in the water-conducting fractured zone and below the water-bearing layer in stratum; due to the distribution of a large quantity of fractures in the target rock stratum with rich carbonatite mineral, injecting a chemical softener to the fractures in the target rock stratum through the drill hole, and making the chemical softener to fully react with the carbonatite mineral in the target rock strata to promote softening of the rock mass structure of the carbonatite and gradually closing the tension fractures in the rock mass under the action of the stress in the mining stratum, to decrease the water conducting ability thereof, and thereby to realize artificially-promoted self-healing of the mining fractures and protection of the underground water-bearing layer.
The specific steps are as following:
a. judging the position of the water-bearing layer in stratum according to a geological borehole column above the mining area, and judging a coal mining area where the water-bearing layer in stratum is damaged by mining according to the height of the water-conducting fractured zone in the overlying strata at the same time; if the water-bearing layer exists within the range of the height of the water-conducting fractured zone, judging that the water-conducting fractured zone in the corresponding area communicates with the water-bearing layer and water-retention repair is required;
if there is no water-bearing layer within the range of the height of the water-conducting fractured zone, judging that water-retention repair is not required;
b. carrying out construction in the area requiring water-retention repair: in the mining area where the water-conducting fractured zone communicates with the water-bearing layer, sampling the rock strata within the range of the corresponding water-conducting fractured zone and below the water-bearing layer, testing the mineral components in the rock strata, and thereby determining the target rock stratum with rich carbonatite mineral;
c. constructing a softener injection drill hole downward in the ground surface corresponding to the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, wherein, the type of the drill hole is determined according to the construction conditions of the ground surface: if construction conditions for arranging a drilling field are available on the ground surface corresponding to the mining area, selecting a vertical drill hole in the ground surface;
otherwise, constructing a horizontal drill hole at a drilling field arranged at an appropriate position on the ground surface outside the mining area;
d. injecting a chemical softener that can easily react with the carbonatite mineral into the softener injection drill hole, and making the chemical softener to fully react with the carbonatite mineral in
2 the target rock stratum to induce plastic flow of the carbonatite rock mass structures, so that the carbonatite rock stratum is subjected to double actions of extrusion exerted by horizontal stress in the mining strata and compaction exerted by vertical stress in the mining strata, and the compression fractures and tension fractures in the target rock stratum gradually close, thereby effectively decreasing the water conducting ability of the rock strata in the tension fractured zone, so as to artificially promote self-healing of the mining fractures and realize protection of underground water-bearing layer.
The setting steps for different types of drill holes are as follows:
if the softener injection drill hole is a vertical drill hole constructed in the ground surface, the planar position of the drill hole should be near the outer side of the boundary of the mining area, at a horizontal distance from the mining boundary which is equal to the distance between the contour line of the water-conducting fractured zone corresponding to the position of the target rock stratum and the mining boundary, and the position of the end hole should be at the middle part of the target rock stratum with rich carbonatite mineral in the vertical direction; if the dimension of the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum exceeds 200-300 meters along the strike direction or dip direction, vertical drill holes are arranged at 200-300 meters interval along the strike direction or dip direction;
if a horizontal directional drill hole is constructed in the ground surface, the trajectory of the horizontal section of the drill hole should be along the position of the target rock stratum with rich carbonatite mineral, at a position laterally deviated from the contour line of the water-conducting fractured zone.
A casing for protecting the vertical drill hole should be provided within a range from the ground surface to 10m below the bottom interface of the water-bearing layer, and the casing is made of an acid corrosion-resistant and high-strength polymeric material, such as PVC; a casing for protecting the horizontal directional hole should be provided within a range from the ground surface to the water-conducting fractured zone, and the casing should be made of an acid corrosion-resistant and high-strength polymeric material, such as PVC.
The height of the water-conducting fractured zone is detected with a field measurement method, i.e., a drilling fluid loss method, or judged with a theoretical calculation method, i.e., "a method for predicting the height of water-conducting fractured zone based on the position of key layer".
The mineral components in the rock strata below the water-bearing layer are tested with an X-ray diffractometer, and a rock stratum with the highest content of carbonatite mineral component is determined as the target rock stratum with rich carbonatite mineral to which the chemical softener is injected.
The chemical softener is an acidic chemical solution comprising hydrochloric acid or sulfuric acid or hydrofluoric acid with a mass fraction of 15%-20%.
Beneficial effects: in the present invention, based on the development law and distribution characteristics of water-conducting fractures in the mining overlying strata, the dissolution and corrosive reactions of acidic chemical substances on carbonatite-rich minerals are fully utilized to effectively weaken the strength of the bearing structures of target rock strata, to induce plastic flow in the rock strata under the compaction action of the stress in the mining strata, and thereby drive the mining fractures in the rock strata to close, so as to artificially promote self-healing of the mining fractures, and finally attain a purpose of decreasing the water conducting ability of fracture channels and protecting the underground water-bearing layer. The present invention is adapted to the determination of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite under different mining conditions, and can provide a guarantee for
The setting steps for different types of drill holes are as follows:
if the softener injection drill hole is a vertical drill hole constructed in the ground surface, the planar position of the drill hole should be near the outer side of the boundary of the mining area, at a horizontal distance from the mining boundary which is equal to the distance between the contour line of the water-conducting fractured zone corresponding to the position of the target rock stratum and the mining boundary, and the position of the end hole should be at the middle part of the target rock stratum with rich carbonatite mineral in the vertical direction; if the dimension of the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum exceeds 200-300 meters along the strike direction or dip direction, vertical drill holes are arranged at 200-300 meters interval along the strike direction or dip direction;
if a horizontal directional drill hole is constructed in the ground surface, the trajectory of the horizontal section of the drill hole should be along the position of the target rock stratum with rich carbonatite mineral, at a position laterally deviated from the contour line of the water-conducting fractured zone.
A casing for protecting the vertical drill hole should be provided within a range from the ground surface to 10m below the bottom interface of the water-bearing layer, and the casing is made of an acid corrosion-resistant and high-strength polymeric material, such as PVC; a casing for protecting the horizontal directional hole should be provided within a range from the ground surface to the water-conducting fractured zone, and the casing should be made of an acid corrosion-resistant and high-strength polymeric material, such as PVC.
The height of the water-conducting fractured zone is detected with a field measurement method, i.e., a drilling fluid loss method, or judged with a theoretical calculation method, i.e., "a method for predicting the height of water-conducting fractured zone based on the position of key layer".
The mineral components in the rock strata below the water-bearing layer are tested with an X-ray diffractometer, and a rock stratum with the highest content of carbonatite mineral component is determined as the target rock stratum with rich carbonatite mineral to which the chemical softener is injected.
The chemical softener is an acidic chemical solution comprising hydrochloric acid or sulfuric acid or hydrofluoric acid with a mass fraction of 15%-20%.
Beneficial effects: in the present invention, based on the development law and distribution characteristics of water-conducting fractures in the mining overlying strata, the dissolution and corrosive reactions of acidic chemical substances on carbonatite-rich minerals are fully utilized to effectively weaken the strength of the bearing structures of target rock strata, to induce plastic flow in the rock strata under the compaction action of the stress in the mining strata, and thereby drive the mining fractures in the rock strata to close, so as to artificially promote self-healing of the mining fractures, and finally attain a purpose of decreasing the water conducting ability of fracture channels and protecting the underground water-bearing layer. The present invention is adapted to the determination of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite under different mining conditions, and can provide a guarantee for
3 water resource protection and water hazard prevention and treatment in coal mining in mining areas.
The method provided in the present invention is reliable and highly practical.
The method of the present invention has the following advantages:
(1) The method of "grasping the principal contradiction" is adopted for the water-conducting fractures in the overlying strata that communicate with the water-bearing layer in stratum, artificial measures are used to promote close and self-healing of the fractures with larger opening and higher overflow capacity in the overlying strata at the mining boundary.
Such a method is not only scientific and reliable, involves lower workload, and has no disturbance to the normal coal mining at the working face, but also can be implemented in the normal coal mining process or after the working face is closed.
(2) The water-rock chemical actions in the mining overlying strata are fully utilized, and a chemical softener is injected artificially to promote softening of the target rock stratum and closing of the fractures. Such a method follows the objective natural laws and has no severe impact on the underground water environment as well.
(3) The present invention is adapted to determination of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite under different mining conditions, can provide a guarantee for water resource protection and water hazard prevention and treatment in coal mining in mining areas with abundant water and fragile surface ecological environment in China. In addition, the method is simple and highly practical.
IV. Description of Drawings Fig. 1 is a plan view of the layout of vertical drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 2 is an A-A sectional view of the layout of vertical drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 3 is a schematic view of closing and self-healing of mining fractures before/after softening of the target rock stratum with rich carbonatite according to the present invention;
Fig. 4 is a plan view of the layout of horizontal directional drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 5 is a B-B sectional view of the layout of horizontal directional drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 6 is a plan view of the layout of the chemical softener injection drill holes in the ground surface at a working face 12301 in a coal mine in the actual application process of the method provided in the present invention.
In the figures: 1 - water-bearing layer; 2 - target rock stratum with rich carbonatite mineral; 3 - vertical drill hole; 4 - contour line of water-conducting fractured zone; 5 -compression fractured zone; 6 -tension fractured zone; 7 - central compacted zone; 8- horizontal directional hole; 9- horizontal stress in mining strata; 10 - vertical stress in mining strata.
V. Embodiments Hereunder the present invention will be further detailed with reference to the drawings and specific
The method provided in the present invention is reliable and highly practical.
The method of the present invention has the following advantages:
(1) The method of "grasping the principal contradiction" is adopted for the water-conducting fractures in the overlying strata that communicate with the water-bearing layer in stratum, artificial measures are used to promote close and self-healing of the fractures with larger opening and higher overflow capacity in the overlying strata at the mining boundary.
Such a method is not only scientific and reliable, involves lower workload, and has no disturbance to the normal coal mining at the working face, but also can be implemented in the normal coal mining process or after the working face is closed.
(2) The water-rock chemical actions in the mining overlying strata are fully utilized, and a chemical softener is injected artificially to promote softening of the target rock stratum and closing of the fractures. Such a method follows the objective natural laws and has no severe impact on the underground water environment as well.
(3) The present invention is adapted to determination of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite under different mining conditions, can provide a guarantee for water resource protection and water hazard prevention and treatment in coal mining in mining areas with abundant water and fragile surface ecological environment in China. In addition, the method is simple and highly practical.
IV. Description of Drawings Fig. 1 is a plan view of the layout of vertical drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 2 is an A-A sectional view of the layout of vertical drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 3 is a schematic view of closing and self-healing of mining fractures before/after softening of the target rock stratum with rich carbonatite according to the present invention;
Fig. 4 is a plan view of the layout of horizontal directional drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 5 is a B-B sectional view of the layout of horizontal directional drill holes in the ground surface in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention;
Fig. 6 is a plan view of the layout of the chemical softener injection drill holes in the ground surface at a working face 12301 in a coal mine in the actual application process of the method provided in the present invention.
In the figures: 1 - water-bearing layer; 2 - target rock stratum with rich carbonatite mineral; 3 - vertical drill hole; 4 - contour line of water-conducting fractured zone; 5 -compression fractured zone; 6 -tension fractured zone; 7 - central compacted zone; 8- horizontal directional hole; 9- horizontal stress in mining strata; 10 - vertical stress in mining strata.
V. Embodiments Hereunder the present invention will be further detailed with reference to the drawings and specific
4 examples. It should be understood that the examples are provided only for describing the present invention, and shall not be deemed as constituting any limitation to the scope of the present invention.
Various equivalent modifications to the present invention made by the person skilled in the art after reading the present invention are deemed as falling into the scope defined by the attached claims.
As shown in Figs. 1-5, in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention, according to the development characteristics of the water-conducting fractured zone in the mining overlying strata under specific mining conditions, the distribution range of a water-conducting fractured zone in the overlying strata that communicates with a water-bearing layer 1 in stratum is determined in the mining area, wherein, the edges of the water-conducting fractured zone are defined by a contour line 4 of the water-conducting fractured zone, the water-conducting fractured zone comprises a compression fractured zone 5 and a tension fractured zone 6, and a central compacted zone 7 is provided in the water-conducting fractured zone, and the central compacted zone 7 is enclosed between the compression fractured zone 5 and the tension fractured zone 6;
In the mining area where the water-conducting fractured zone communicates with the water-bearing layer 1 in stratum 1, drill holes are constructed from the ground surface to a target rock stratum 2 with rich carbonatite mineral which is in the water-conducting fractured zone and below the water-bearing layer 1 in stratum, a softener (e.g., an acidic chemical agent) is injected to fully react with the carbonatite mineral in the target rock stratum, to promote plastic flow of the rock mass structures and to induce gradual close of the tension fractures in the rock mass under the action of the stress in the mining strata, and thereby to decrease the water conducting ability thereof, to artificially promote self-healing of the mining fractures and to realize protection of the underground water-bearing layer.
Specifically, the method comprises the following steps:
a. judging a coal mining area where a water-bearing layer 1 in stratum is damaged by the mining according to the height of a water-conducting fractured zone in the overlying strata and the geological borehole column; if the water-bearing layer 1 exists within the range of the height of the water-conducting fractured zone, judging that the water-conducting fractured zone in the corresponding area communicates with the water-bearing layer 1 and corresponding chemical softener injection drill holes have to be arranged; if there is no water-bearing layer 1 within the range of the height of the water-conducting fractured zone, judging that no drill hole is required.
The height of the water-conducting fractured zone is detected with a field measurement method, i.e., a drilling fluid loss method, or may be judged with a theoretical calculation method, i.e., "a method for predicting the height of water-conducting fractured zone based on the position of key layer".
b. sampling and testing the mineral components in the rock strata within the range of the corresponding water-conducting fractured zone and below the water-bearing layer 1 in the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, and determining the target rock stratum 2 with rich carbonatite mineral.
The mineral components in the rock strata below the water-bearing layer 1 are tested with an X-ray diffractometer, and a rock stratum with the highest content of carbonatite mineral component is determined as the target rock stratum 2 with rich carbonatite mineral to which the chemical softener is injected.
c. constructing a chemical softener injection drill hole in the ground surface corresponding to the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, wherein, the type of the drill hole can be determined according to the construction conditions of the ground surface: if construction conditions for arranging a drilling field are available on the ground surface corresponding to the mining area, selecting a vertical drill hole 3 in the ground surface; otherwise constructing a horizontal directional drill hole 8 at a drilling field arranged at an appropriate position on the ground surface outside the mining area.
The setting steps for different types of drill holes are as follows:
if a vertical drill hole 3 is constructed in the ground surface, the planar position of the drill hole should be near the outer side of the boundary of the mining area, at a horizontal distance from the mining boundary which is equal to the distance between the contour line 4 of the water-conducting fractured zone corresponding to the position of the target rock stratum 2 with rich carbonatite mineral and the mining boundary, and the position of the end hole should be at the middle part of the target rock stratum 2 with rich carbonatite mineral in the vertical direction; if the dimension of the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum exceeds 200-300 meters along the strike direction or dip direction, vertical drill holes 43 are arranged at 200-300 meters interval along the strike direction or dip direction;
if a horizontal directional drill hole 8 is constructed in the ground surface, the trajectory of the horizontal section of the drill hole should be along the position of the target rock stratum 2 with rich carbonatite mineral, at a position laterally deviated from the contour line 4 of the water-conducting fractured zone.
A casing for protecting the vertical drill hole 3 should be provided within a range from the ground surface to 10m below the bottom interface of the water-bearing layer 1, and the casing should be made of an acid corrosion-resistant and high-strength polymeric material, such as PVC.
A casing for protecting the horizontal directional hole 8 should be provided within a range from the ground surface to the water-conducting fractured zone, and the casing should be made of an acid corrosion-resistant and high-strength polymeric material, such as PVC.
d.
injecting a chemical softener that can easily react with the carbonatite mineral into the softener injection drill hole, and making the chemical softener to ftilly react with the carbonatite mineral in the target rock stratum to induce plastic flow of the carbonatite rock mass structures, so that the carbonatite rock stratum is subjected to double actions of extrusion exerted by horizontal stress 9 in the mining strata and compaction exerted by vertical stress 10 in the mining strata, and the compression fractures and tension fractures in the target rock stratum gradually close, thereby effectively decreasing the water conducting ability of the rock strata in the tension fractured zone, so as to artificially promote self-healing of the mining fractures and realize protection of underground water-bearing layer.
The mass fraction of the acidic chemical solution is in 15%-20%.
The following tables 1 and 2 show judging results of borehole columns and the height of water-conducting fractured zone in different mining areas at a working face 12301 during the actual application process in a coal mine. It can be seen from the tables that the height of the water-conducting fractured zone and the condition of in communication with the water-bearing layer stratum are obviously different in the two borehole areas at the working face 12301. The water-conducting fractured zone in the overlying strata in the borehole area Ti does not communicate with the water-bearing layer in stratum, while the water-conducting fractures in the overlying strata in the borehole area T2 have developed to the top interface of the bedrock and directly communicate with the water-bearing layer in stratum. Therefore, the target rock stratum with rich carbonatite mineral within the range of the water-conducting fractured zone and below the water-bearing layer in the borehole area T2 has to be chemically softened to promote plastic flow in the rock mass and closing and self-healing of the mining fractures.
Table 1 shows the borehole column and judging result of key layer position in area Ti at working face 12301 in a coal mine;
Layer Thickness Burial Lithology Remarks No. /m Depth / m 1 15.25 15.25 Yellow soil Water-bearing 2 100.20 115.45 Conglomerate layer Argillaceous 3 20.06 135.51 siltstone .
Coarse-grain 4 15.30 150.81 sandstone cu I
c 5 3.15 153.96 Argillaceous siltstone o N Sandy 6 8.20 162.16 -cs mudstone (1) Fine-grain -r 7 4.40 166.56 __ ... ) . sandstone c.) ct . o c= Argillaceous 4 to 8 18.18 184.74 ¨ sandstone au til ....
c.) Medium-grain z 9 12.50 197.24 -o sandstone =
o Sandy o 10 10.64 207.88 4 mudstone a) ,.. Sandy ct 11 8.55 216.43 3 claystone c.
O Fine-grain 12 5.30 221.73 sandstone :a. Sandy to 13 10.47 232.20 '5 mudstone = Fine-grain II 14 13.77 245.97 sandstone 15 4.78 250.75 1-2 coal Table 2 shows the borehole column and judging result of key layer position in area T2 at working face 12301 in a coal mine;
Burial Layer Thickness Depth / Lithology Remarks 17.06 17.06 Yellow soil 1 1.40 18.46 Coarse-grain mom sandstone II 2 80.9 Water-99.36 Conglomerate bearing layer 3 3.87 103.23 Fine-grain sandstone 4 10.62 113.85 Siltstone
Various equivalent modifications to the present invention made by the person skilled in the art after reading the present invention are deemed as falling into the scope defined by the attached claims.
As shown in Figs. 1-5, in the water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to the present invention, according to the development characteristics of the water-conducting fractured zone in the mining overlying strata under specific mining conditions, the distribution range of a water-conducting fractured zone in the overlying strata that communicates with a water-bearing layer 1 in stratum is determined in the mining area, wherein, the edges of the water-conducting fractured zone are defined by a contour line 4 of the water-conducting fractured zone, the water-conducting fractured zone comprises a compression fractured zone 5 and a tension fractured zone 6, and a central compacted zone 7 is provided in the water-conducting fractured zone, and the central compacted zone 7 is enclosed between the compression fractured zone 5 and the tension fractured zone 6;
In the mining area where the water-conducting fractured zone communicates with the water-bearing layer 1 in stratum 1, drill holes are constructed from the ground surface to a target rock stratum 2 with rich carbonatite mineral which is in the water-conducting fractured zone and below the water-bearing layer 1 in stratum, a softener (e.g., an acidic chemical agent) is injected to fully react with the carbonatite mineral in the target rock stratum, to promote plastic flow of the rock mass structures and to induce gradual close of the tension fractures in the rock mass under the action of the stress in the mining strata, and thereby to decrease the water conducting ability thereof, to artificially promote self-healing of the mining fractures and to realize protection of the underground water-bearing layer.
Specifically, the method comprises the following steps:
a. judging a coal mining area where a water-bearing layer 1 in stratum is damaged by the mining according to the height of a water-conducting fractured zone in the overlying strata and the geological borehole column; if the water-bearing layer 1 exists within the range of the height of the water-conducting fractured zone, judging that the water-conducting fractured zone in the corresponding area communicates with the water-bearing layer 1 and corresponding chemical softener injection drill holes have to be arranged; if there is no water-bearing layer 1 within the range of the height of the water-conducting fractured zone, judging that no drill hole is required.
The height of the water-conducting fractured zone is detected with a field measurement method, i.e., a drilling fluid loss method, or may be judged with a theoretical calculation method, i.e., "a method for predicting the height of water-conducting fractured zone based on the position of key layer".
b. sampling and testing the mineral components in the rock strata within the range of the corresponding water-conducting fractured zone and below the water-bearing layer 1 in the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, and determining the target rock stratum 2 with rich carbonatite mineral.
The mineral components in the rock strata below the water-bearing layer 1 are tested with an X-ray diffractometer, and a rock stratum with the highest content of carbonatite mineral component is determined as the target rock stratum 2 with rich carbonatite mineral to which the chemical softener is injected.
c. constructing a chemical softener injection drill hole in the ground surface corresponding to the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, wherein, the type of the drill hole can be determined according to the construction conditions of the ground surface: if construction conditions for arranging a drilling field are available on the ground surface corresponding to the mining area, selecting a vertical drill hole 3 in the ground surface; otherwise constructing a horizontal directional drill hole 8 at a drilling field arranged at an appropriate position on the ground surface outside the mining area.
The setting steps for different types of drill holes are as follows:
if a vertical drill hole 3 is constructed in the ground surface, the planar position of the drill hole should be near the outer side of the boundary of the mining area, at a horizontal distance from the mining boundary which is equal to the distance between the contour line 4 of the water-conducting fractured zone corresponding to the position of the target rock stratum 2 with rich carbonatite mineral and the mining boundary, and the position of the end hole should be at the middle part of the target rock stratum 2 with rich carbonatite mineral in the vertical direction; if the dimension of the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum exceeds 200-300 meters along the strike direction or dip direction, vertical drill holes 43 are arranged at 200-300 meters interval along the strike direction or dip direction;
if a horizontal directional drill hole 8 is constructed in the ground surface, the trajectory of the horizontal section of the drill hole should be along the position of the target rock stratum 2 with rich carbonatite mineral, at a position laterally deviated from the contour line 4 of the water-conducting fractured zone.
A casing for protecting the vertical drill hole 3 should be provided within a range from the ground surface to 10m below the bottom interface of the water-bearing layer 1, and the casing should be made of an acid corrosion-resistant and high-strength polymeric material, such as PVC.
A casing for protecting the horizontal directional hole 8 should be provided within a range from the ground surface to the water-conducting fractured zone, and the casing should be made of an acid corrosion-resistant and high-strength polymeric material, such as PVC.
d.
injecting a chemical softener that can easily react with the carbonatite mineral into the softener injection drill hole, and making the chemical softener to ftilly react with the carbonatite mineral in the target rock stratum to induce plastic flow of the carbonatite rock mass structures, so that the carbonatite rock stratum is subjected to double actions of extrusion exerted by horizontal stress 9 in the mining strata and compaction exerted by vertical stress 10 in the mining strata, and the compression fractures and tension fractures in the target rock stratum gradually close, thereby effectively decreasing the water conducting ability of the rock strata in the tension fractured zone, so as to artificially promote self-healing of the mining fractures and realize protection of underground water-bearing layer.
The mass fraction of the acidic chemical solution is in 15%-20%.
The following tables 1 and 2 show judging results of borehole columns and the height of water-conducting fractured zone in different mining areas at a working face 12301 during the actual application process in a coal mine. It can be seen from the tables that the height of the water-conducting fractured zone and the condition of in communication with the water-bearing layer stratum are obviously different in the two borehole areas at the working face 12301. The water-conducting fractured zone in the overlying strata in the borehole area Ti does not communicate with the water-bearing layer in stratum, while the water-conducting fractures in the overlying strata in the borehole area T2 have developed to the top interface of the bedrock and directly communicate with the water-bearing layer in stratum. Therefore, the target rock stratum with rich carbonatite mineral within the range of the water-conducting fractured zone and below the water-bearing layer in the borehole area T2 has to be chemically softened to promote plastic flow in the rock mass and closing and self-healing of the mining fractures.
Table 1 shows the borehole column and judging result of key layer position in area Ti at working face 12301 in a coal mine;
Layer Thickness Burial Lithology Remarks No. /m Depth / m 1 15.25 15.25 Yellow soil Water-bearing 2 100.20 115.45 Conglomerate layer Argillaceous 3 20.06 135.51 siltstone .
Coarse-grain 4 15.30 150.81 sandstone cu I
c 5 3.15 153.96 Argillaceous siltstone o N Sandy 6 8.20 162.16 -cs mudstone (1) Fine-grain -r 7 4.40 166.56 __ ... ) . sandstone c.) ct . o c= Argillaceous 4 to 8 18.18 184.74 ¨ sandstone au til ....
c.) Medium-grain z 9 12.50 197.24 -o sandstone =
o Sandy o 10 10.64 207.88 4 mudstone a) ,.. Sandy ct 11 8.55 216.43 3 claystone c.
O Fine-grain 12 5.30 221.73 sandstone :a. Sandy to 13 10.47 232.20 '5 mudstone = Fine-grain II 14 13.77 245.97 sandstone 15 4.78 250.75 1-2 coal Table 2 shows the borehole column and judging result of key layer position in area T2 at working face 12301 in a coal mine;
Burial Layer Thickness Depth / Lithology Remarks 17.06 17.06 Yellow soil 1 1.40 18.46 Coarse-grain mom sandstone II 2 80.9 Water-99.36 Conglomerate bearing layer 3 3.87 103.23 Fine-grain sandstone 4 10.62 113.85 Siltstone
5 8.88 122.73 Argillaceous sandstone Fine-grain P 6 3.86 126.59 e sandstone eu 7 5.90 132.49 Sandy =
o mudstone N
-a 8 12.92 145.41 Limestone a) P 9 3.30 148.71 Sandy c.) mudstone w Medium-th c 10 32.70 181.41 grain ..t.--U ,Y
= sandstone o -a o c 11 1.18 182.59 1-1 coal ..., .1:
o Y. Sandy ci1:1 eu 12 0.87 183.46 mudstone 3 ... 13 0.12 183.58 Charcoal o mudstone = 14 1.25 184.83 Sandy .. mudstone bz = 15 0.10 184.93 Charcoal mudstone 16 4.30 189.23 Siltstone 17 2.20 191.43 Sandy mudstone 18 0.11 191.54 Fine-grain sandstone , 19 2.69 194.23 Sandy mudstone 20 0.30 194.53 1-2 top coal ir 21 9.78 204.31 Silt sandstone 22 9.60 213.91 Mudstone mem Sandy 23 1.32 215.23 mudstone 24 5.92 221.15 1-2 coal As shown in Fig. 6, the ground surface at the working face is relatively smooth and flat and suitable for arranging a drilling field for constructing vertical drill holes, thus vertical drill holes are constructed in the ground surface corresponding to the borehole area T2.
Through sampling and testing the mineral components in the rock strata within the range of the water-conducting fractured zone and below the water-bearing layer in the borehole area T2, it is found that the rock stratum No.
8 has rich carbonatite mineral with the highest content of up to 83%.
Therefore, the end hole position of the drill hole in the ground surface is at the middle part of the limestone stratum in the vertical direction, and the corresponding vertical depth is 139 m. As the advance length of the mining area in strike direction in the borehole area T2 is 560 m, drill holes are arranged at a horizontal interval of 300 m. According to relevant measure and calculation results, the distance between the laterally deviated contour line of the water-conducting fractured zone in the overlying strata in the borehole area T2 and the mining boundary of the limestone stratum No. 8 is 35m.
Therefore, the horizontal positions of the drill holes are arranged on the basis of that distance.
In the present invention, based on the development law and distribution characteristics of mining-induced water-conducting fractures in the overlying strata, the chemical reaction effects (e.g., dissolution and corrosion) of acidic chemical substances on carbonatite-rich minerals are fully utilized to effectively weaken the strength of the bearing structure of target rock strata, to promote plastic flow of the rock strata under the compaction action of the stress in the mining strata, and thereby drive the mining fractures in the rock strata to close, so as to artificially promote self-healing of the mining fractures, and finally realize a purpose of decreasing the water conducting ability of fracture channels and protecting the underground water-bearing layer. The present invention is adapted to determination of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite under different mining conditions, and can provide a guarantee for water resource protection and water hazard prevention and treatment in coal mining in mining areas. The method provided in the present invention is reliable and highly practical.
o mudstone N
-a 8 12.92 145.41 Limestone a) P 9 3.30 148.71 Sandy c.) mudstone w Medium-th c 10 32.70 181.41 grain ..t.--U ,Y
= sandstone o -a o c 11 1.18 182.59 1-1 coal ..., .1:
o Y. Sandy ci1:1 eu 12 0.87 183.46 mudstone 3 ... 13 0.12 183.58 Charcoal o mudstone = 14 1.25 184.83 Sandy .. mudstone bz = 15 0.10 184.93 Charcoal mudstone 16 4.30 189.23 Siltstone 17 2.20 191.43 Sandy mudstone 18 0.11 191.54 Fine-grain sandstone , 19 2.69 194.23 Sandy mudstone 20 0.30 194.53 1-2 top coal ir 21 9.78 204.31 Silt sandstone 22 9.60 213.91 Mudstone mem Sandy 23 1.32 215.23 mudstone 24 5.92 221.15 1-2 coal As shown in Fig. 6, the ground surface at the working face is relatively smooth and flat and suitable for arranging a drilling field for constructing vertical drill holes, thus vertical drill holes are constructed in the ground surface corresponding to the borehole area T2.
Through sampling and testing the mineral components in the rock strata within the range of the water-conducting fractured zone and below the water-bearing layer in the borehole area T2, it is found that the rock stratum No.
8 has rich carbonatite mineral with the highest content of up to 83%.
Therefore, the end hole position of the drill hole in the ground surface is at the middle part of the limestone stratum in the vertical direction, and the corresponding vertical depth is 139 m. As the advance length of the mining area in strike direction in the borehole area T2 is 560 m, drill holes are arranged at a horizontal interval of 300 m. According to relevant measure and calculation results, the distance between the laterally deviated contour line of the water-conducting fractured zone in the overlying strata in the borehole area T2 and the mining boundary of the limestone stratum No. 8 is 35m.
Therefore, the horizontal positions of the drill holes are arranged on the basis of that distance.
In the present invention, based on the development law and distribution characteristics of mining-induced water-conducting fractures in the overlying strata, the chemical reaction effects (e.g., dissolution and corrosion) of acidic chemical substances on carbonatite-rich minerals are fully utilized to effectively weaken the strength of the bearing structure of target rock strata, to promote plastic flow of the rock strata under the compaction action of the stress in the mining strata, and thereby drive the mining fractures in the rock strata to close, so as to artificially promote self-healing of the mining fractures, and finally realize a purpose of decreasing the water conducting ability of fracture channels and protecting the underground water-bearing layer. The present invention is adapted to determination of a water retention method for promoting self-healing of mining fractures by chemically softening carbonatite under different mining conditions, and can provide a guarantee for water resource protection and water hazard prevention and treatment in coal mining in mining areas. The method provided in the present invention is reliable and highly practical.
Claims (7)
1. A water retention method for promoting self-healing of mining fractures by chemically softening carbonatite, characterized in that: according to the development characteristics of the water-conducting fractured zone in the mining overlying strata under specific mining conditions, determining the information of the distribution range of a water-conducting fractured zone in the overlying strata that communicates with a water-bearing layer in stratum in a mining area, and acquiring information of a rock stratum with rich carbonatite mineral at the same time; in the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, constructing a drill hole from the ground surface to a target rock stratum with rich carbonatite mineral which is in the water-conducting fractured zone and below the water-bearing layer in stratum; due to the distribution of a large quantity of fractures in the target rock stratum with rich carbonatite mineral, injecting a chemical softener to the fractures in the target rock stratum through the drill hole, and making the chemical softener to fully react with the carbonatite mineral in the target rock strata to promote softening of the rock mass structure of the carbonatite and gradually closing the tension fractures in the rock mass under the action of the stress in the mining stratum, to decrease the water conducting ability thereof, and thereby to realize artificially-promoted self-healing of the mining fractures and protection of the underground water-bearing layer.
2. The water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to claim 1, characterized in that: said method comprises the following steps:
a. judging the position of the water-bearing layer in stratum according to a geological borehole column above the mining area, and judging a coal mining area where the water-bearing layer in stratum is damaged by mining according to the height of the water-conducting fractured zone in the overlying strata at the same time; if the water-bearing layer exists within the range of the height of the water-conducting fractured zone, judging that the water-conducting fractured zone in the corresponding area communicates with the water-bearing layer and water-retention repair is required; if there is no water-bearing layer within the range of the height of the water-conducting fractured zone, judging that water-retention repair is not required;
b. carrying out construction in the area requiring water-retention repair: in the mining area where the water-conducting fractured zone communicates with the water-bearing layer, sampling the rock strata within the range of the corresponding water-conducting fractured zone and below the water-bearing layer, testing the mineral components in the rock strata, and thereby determining the target rock stratum with rich carbonatite mineral;
c. constructing a softener injection drill hole downward in the ground surface corresponding to the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, wherein, the type of the drill hole is determined according to the construction conditions of the ground surface: if construction conditions for arranging a drilling field are available on the ground surface corresponding to the mining area, selecting a vertical drill hole in the ground surface; otherwise, constructing a horizontal drill hole at a drilling field arranged at an appropriate position on the ground surface outside the mining area;
d. injecting a chemical softener that can easily react with the carbonatite mineral into the softener injection drill hole, and making the chemical softener to fully react with the carbonatite mineral in the target rock stratum to induce plastic flow of the carbonatite rock mass structures, so that the carbonatite rock stratum is subjected to double actions of extrusion exerted by horizontal stress in the mining strata and compaction exerted by vertical stress in the mining strata, and the compression fractures and tension fractures in the target rock stratum gradually close, thereby effectively decreasing the water conducting ability of the rock strata in the tension fractured zone, so as to artificially promote self-healing of the mining fractures and realize protection of underground water-bearing layer.
a. judging the position of the water-bearing layer in stratum according to a geological borehole column above the mining area, and judging a coal mining area where the water-bearing layer in stratum is damaged by mining according to the height of the water-conducting fractured zone in the overlying strata at the same time; if the water-bearing layer exists within the range of the height of the water-conducting fractured zone, judging that the water-conducting fractured zone in the corresponding area communicates with the water-bearing layer and water-retention repair is required; if there is no water-bearing layer within the range of the height of the water-conducting fractured zone, judging that water-retention repair is not required;
b. carrying out construction in the area requiring water-retention repair: in the mining area where the water-conducting fractured zone communicates with the water-bearing layer, sampling the rock strata within the range of the corresponding water-conducting fractured zone and below the water-bearing layer, testing the mineral components in the rock strata, and thereby determining the target rock stratum with rich carbonatite mineral;
c. constructing a softener injection drill hole downward in the ground surface corresponding to the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum, wherein, the type of the drill hole is determined according to the construction conditions of the ground surface: if construction conditions for arranging a drilling field are available on the ground surface corresponding to the mining area, selecting a vertical drill hole in the ground surface; otherwise, constructing a horizontal drill hole at a drilling field arranged at an appropriate position on the ground surface outside the mining area;
d. injecting a chemical softener that can easily react with the carbonatite mineral into the softener injection drill hole, and making the chemical softener to fully react with the carbonatite mineral in the target rock stratum to induce plastic flow of the carbonatite rock mass structures, so that the carbonatite rock stratum is subjected to double actions of extrusion exerted by horizontal stress in the mining strata and compaction exerted by vertical stress in the mining strata, and the compression fractures and tension fractures in the target rock stratum gradually close, thereby effectively decreasing the water conducting ability of the rock strata in the tension fractured zone, so as to artificially promote self-healing of the mining fractures and realize protection of underground water-bearing layer.
3. The water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to claim 1, characterized in that, the setting steps for different types of drill holes are as follows:
if the softener injection drill hole is a vertical drill hole constructed in the ground surface, the planar position of the drill hole should be near the outer side of the boundary of the mining area, at a horizontal distance from the mining boundary which is equal to the distance between the contour line of the water-conducting fractured zone corresponding to the position of the target rock stratum and the mining boundary, and the position of the end hole should be at the middle part of the target rock stratum with rich carbonatite mineral in the vertical direction; if the dimension of the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum exceeds 200-300 meters along the strike direction or dip direction, vertical drill holes are arranged at 200-300 meters interval along the strike direction or dip direction;
if a horizontal directional drill hole is constructed in the ground surface, the trajectory of the horizontal section of the drill hole should be along the position of the target rock stratum with rich carbonatite mineral, at a position laterally deviated from the contour line of the water-conducting fractured zone.
if the softener injection drill hole is a vertical drill hole constructed in the ground surface, the planar position of the drill hole should be near the outer side of the boundary of the mining area, at a horizontal distance from the mining boundary which is equal to the distance between the contour line of the water-conducting fractured zone corresponding to the position of the target rock stratum and the mining boundary, and the position of the end hole should be at the middle part of the target rock stratum with rich carbonatite mineral in the vertical direction; if the dimension of the mining area where the water-conducting fractured zone communicates with the water-bearing layer in stratum exceeds 200-300 meters along the strike direction or dip direction, vertical drill holes are arranged at 200-300 meters interval along the strike direction or dip direction;
if a horizontal directional drill hole is constructed in the ground surface, the trajectory of the horizontal section of the drill hole should be along the position of the target rock stratum with rich carbonatite mineral, at a position laterally deviated from the contour line of the water-conducting fractured zone.
4. The water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to claim 3, characterized in that, a casing for protecting the vertical drill hole should be provided within a range from the ground surface to 10m below the bottom interface of the water-bearing layer, and the casing is made of an acid corrosion-resistant and high-strength polymeric material, such as PVC; a casing for protecting the horizontal directional hole should be provided within a range from the ground surface to the water-conducting fractured zone, and the casing should be made of an acid corrosion-resistant and high-strength polymeric material, such as PVC.
5. The water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to claim 1, characterized in that, the height of the water-conducting fractured zone is detected with a field measurement method, i.e., a drilling fluid loss method, or judged with a theoretical calculation method, i.e., "a method for predicting the height of water-conducting fractured zone based on the position of key layer".
6. The water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to claim 1, characterized in that, the mineral components in the rock strata below the water-bearing layer are tested with an X-ray diffractometer, and a rock stratum with the highest content of carbonatite mineral component is determined as the target rock stratum with rich carbonatite mineral to which the chemical softener is injected.
7. The water retention method for promoting self-healing of mining fractures by chemically softening carbonatite according to claim 1, characterized in that, the chemical softener is an acidic chemical solution comprising hydrochloric acid or sulfuric acid or hydrofluoric acid with a mass fraction of 15%-20%.
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| CN201810444777.5A CN108590717B (en) | 2018-05-10 | 2018-05-10 | The water-retaining method of chemical tendering carbonate rock promotion mining induced fissure selfreparing |
| PCT/CN2018/094416 WO2019214031A1 (en) | 2018-05-10 | 2018-07-04 | Water retention method for promoting self-repairing of mining-induced fracture by chemically softening carbonate rock |
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| CN100467829C (en) * | 2006-11-17 | 2009-03-11 | 中国矿业大学 | Water-protection coal-mining method using structural key layer as waterproof layer |
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| US9920606B2 (en) * | 2013-07-31 | 2018-03-20 | Schlumberger Technology Corporation | Preparation method, formulation and application of chemically retarded mineral acid for oilfield use |
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| CN104879113A (en) * | 2015-06-12 | 2015-09-02 | 中国石油化工股份有限公司 | Compound acid fracturing method for carbonate reservoir |
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- 2018-07-04 RU RU2019131559A patent/RU2737618C1/en active
- 2018-07-04 AU AU2018418035A patent/AU2018418035B2/en active Active
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| Publication number | Publication date |
|---|---|
| WO2019214031A1 (en) | 2019-11-14 |
| AU2018418035A1 (en) | 2019-11-28 |
| CN108590717A (en) | 2018-09-28 |
| AU2018418035B2 (en) | 2021-08-05 |
| RU2737618C1 (en) | 2020-12-01 |
| CN108590717B (en) | 2019-11-26 |
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