A method for determining the water-richness of loose aquifers controlled by fracture structures

Abstract

The present invention discloses a method for determining the water-richness of a loose aquifer controlled by a fracture structure, which relates to the field of hydrogeological and hydrodynamic condition analysis. The quantitative partitioning of the fracture complexity comprises obtaining a fractal dimension value level and a fractal dimension value quantitative partitioning. The fractal dimension value level obtaining comprises the following steps: S1, obtaining a box dimension N (r i ); S2, calculate the fractal dimension value Ds; S3, determine the fractal dimension level, the fractal dimension value quantitative partitioning includes: using the determined fractal dimension value Ds, using suffer to partition the Ds value according to the determined fractal dimension threshold, to obtain a fracture fractal dimension map, on this basis superimpose the structural outline map, to achieve quantitative partitioning according to the fractal dimension value, including the acquisition of the unit water yield value of the loose layer and the comparison of the unit water yield richness, which includes the following steps: S1, the acquisition of the unit water yield value of the loose layer, S2, the comparison of the unit water yield richness, the technical personnel of the present invention can easily understand the fracture control method based on, and the indicators are easy to obtain, which is convenient for practical application in the field.

Description

Technical Field

[0001] The invention relates to the field of hydrogeological and hydrodynamic condition analysis, and specifically to a method for determining the water-richness of a loose aquifer controlled by a fracture structure. Background Art

[0002] The Carboniferous-Permian coal seams mined in coal mines in eastern my country generally have a 10-40m thick ancient weathering crust. The thick loose soil layer deposited in the Neogene and Quaternary periods is unconformably covered, generally 300-500m. The thickness of the coal-bearing wind oxidation zone is a geological body with high earth pressure and high water pressure, weak and broken, and overall poor engineering geological properties. Threatened by surface water bodies and Quaternary water-bearing alluvial layers, shallow coal in some coalfields is difficult to mine. Exploring the water-richness of the loose layer will help to reasonably increase the upper limit of shallow coal seam mining, safely and steadily reduce the waterproof coal pillar, liberate a large amount of stagnant coal, and improve resource recovery rate, which is of great significance to coal mine production. However, the loose layer is subject to its own special geological structure, and its hydrodynamic conditions are extremely difficult to control. For example, the occurrence conditions of the loose layer have their own particularity, and the top surface of the loose layer is undulating and extremely uneven. There is still a lack of control under high-density engineering control within a ten-meter unit in the eastern mining area. And due to the regional incompleteness of the aquifer below the loose layer, that is, the bottom aquifer connected to the bedrock surface, the recharge, diameter and drainage rules of one of the hydrodynamic conditions of the loose layer are also difficult to control. These conditions will further affect the water-rich law of the loose layer. The water-richness of the loose layer varies greatly. For example, the unit water yield of the 5-6-1 hole in the Huainan coalfield is 1.416l / s·m. According to the detailed rules for water prevention and control, the water-richness of the loose layer should be strong water-rich, while the unit water yield of the 5-6 Kz3 hole is 0.00096l / s·m. According to the detailed rules for water prevention and control, the water-richness of the loose layer should be extremely weak water-rich, and the water yield differs by 104 orders of magnitude. For example, the water yield of the 07 hole in the Huaibei coalfield is 1.312 l / s·m. According to the detailed rules for water control, the loose layer water-richness should be classified as strong water-richness, while the unit water yield of the 29-302 hole is 0.00093 l / s·m. According to the detailed rules for water control, the loose layer water-richness should be classified as extremely weak water-richness. The difference in water yield is 10 4 Order of magnitude.

[0003] Such complex hydrogeological conditions make it difficult for on-site personnel to grasp the water-rich law of loose layers, and some water inrush disasters have also occurred in actual production. For example, at 18:55 on January 30, 2015, a water inrush accident occurred at the 866-1 fully-mechanized mining face of Zhuxianzhuang Coal Mine of Huaibei Mining Group. According to preliminary analysis, the source of the water inrush was the water content of the loose layer on the upper part of the working face affected by mining. The most typical example is the Qidong Mine in Huaibei Coalfield. Since it was put into production in 2002, Qidong Mine has experienced 17 frame-pressing water inrush accidents in 8 fully-mechanized mining faces, including 3222, 7114, 6130, and 7121. Among them, the first mining face 3222 had a frame-pressing water inrush accident. The water disaster in the loose layer caused huge losses and threats to the Qidong Mine. It is particularly important to explore the water-rich law of the loose layer. In production practice, it is found that the complexity of the structure is one of the factors that directly affect the efficiency and safety of coal mining. It not only determines the size and range of the groundwater flow space, but also plays a decisive role in the water inrush channel and the amount of water generated during mine mining. The geological structural conditions control the occurrence of mine water hazards. However, previous studies on the complexity of regional fault structures have focused on qualitative evaluation in order to judge the stability of rock formations, but there are few discoveries involving the control of structural complexity on the fourth aquifer in the loose layer. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a method for determining the water richness of loose aquifers controlled by fracture structures. The fracture control method based on the present invention is easy for technicians to understand, and the indicators are easy to obtain, which is convenient for practical application in the field.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for determining the water-richness of a loose aquifer controlled by fracture structures, wherein the fracture complexity quantitative zoning includes obtaining fractal dimension value grades and fractal dimension value quantitative zoning.

[0007] Furthermore, the obtaining of the fractal dimension value level comprises the following steps:

[0008] S1. Get the box dimension N(r i ), after clarifying the scope of the study area, the regional structural traces are covered by the grid method, and the grid length r0 is set according to the grid length r0. i Record the number of grids with fracture traces N(r i ), where r is the initial mesh edge length; N(r i ): box dimension value;

[0009] S2. Calculate the fractal dimension value Ds. Use the linear regression method to perform correlation analysis on lgN(r) and lg(r). The fractal dimension value Ds is calculated according to formula (1). The Ds value with a correlation coefficient greater than 0.95 is selected as the valid array.

[0010] Formula (1):

[0011] S3. Determine the dimensionality level. Combine the characteristics of the obtained Ds data, analyze its maximum, minimum and average values, determine the level threshold, and divide its level standards into four levels: simple, medium, relatively complex, and complex.

[0012] Furthermore, the fractal dimension value quantitative partitioning includes: using a determined fractal dimension value Ds, using suffer to partition the Ds value according to a determined fractal dimension threshold, obtaining a fracture fractal dimension map, and superimposing a structural outline map on this basis to achieve quantitative partitioning according to the fractal dimension value, and the water-richness of the loose layer under different fault complexity, including the acquisition of the unit water yield value of the loose layer and the comparison of the unit water yield, including the following steps:

[0013] S1, the unit water inflow value of the loose layer is obtained. The representative mining areas under different structural levels are found on the fractal quantitative zoning map. The pumping test is carried out on the representative mining areas under different levels. The data of the same aquifer in different mines are used for comparison. The water inflow Q and stable drawdown S of the loose layer water inflow test data of each mine are recorded. The unit water inflow calculation formula (2) is used to obtain the q value.

[0014] Formula (2):

[0015] S2. Comparison of water-richness per unit yield. A horizontal comparison of the unit yields of representative mining areas at different levels obtained in S1 is made, and a bar graph is drawn to determine the level corresponding to the unit yield values ​​under the structural complexity, medium, and simple levels, thereby determining the control of structural complexity on the water-richness of the loose layer. Areas with a higher degree of fault development, that is, areas with more complex fault structures, are conducive to the collection of water by underground aquifers. Generally, there is a positive correlation between the water-richness of the rock layer and the higher the structural complexity, that is, the higher the complexity, the stronger the water-richness.

[0016] Beneficial effects of the present invention: The fracture control method based on the present invention is easy for technicians to understand, and the indicators are easy to obtain, which is convenient for on-site application and practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings.

[0018] Figure 1 It is a flow chart of the present invention;

[0019] Figure 2construct trace plots;

[0020] Figure 3 Grid division diagram;

[0021] Figure 4 Fractal dimension value classification table;

[0022] Figure 5 List of unit water inflow of loose layers with different structural complexity;

[0023] Figure 6 Fractal dimensionality hierarchical partition diagram;

[0024] Figure 7 Comparison of water richness of loose layers at different levels. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inside", "all around" and the like indicating orientation or positional relationship are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the components or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0027] A method for determining the water richness of a loose aquifer controlled by a fracture structure includes quantitative zoning of fracture complexity and comparison of water richness of a loose layer under different fracture complexity. The Huaibei coalfield is used as an example for explanation. The quantitative zoning of fracture complexity includes obtaining fractal dimension value levels and quantitative zoning of fractal dimension values.

[0028] S1. Obtain the box dimension N(ri), and take the structural trace of the Huaibei coalfield area, such as Figure 2 As shown in Figure 1, a square grid with a side length of r0 = 5000m is selected as the standard grid to cover the study area. The study area is divided into several blocks, and each block is numbered and marked in a certain order. Figure 3 As shown. Based on the standard grid, first take ri = r0 / 2 and count the number of grids containing fracture traces N (r i). Then the grid size is continuously reduced, taking r = 1 / 2, 1 / 4, 1 / 8, 1 / 16 respectively, to obtain the corresponding number of grids N(r), and move according to the step size of r0 / 2 until all the grids in the study area are counted. r: initial grid side length; N(ri): box dimension value.

[0029] S2. Calculate the fractal dimension value Ds, and use the linear regression method to perform correlation analysis on lgN(r) and lg(r). The calculation of the fractal dimension value Ds is based on formula (1), and the Ds value with a correlation coefficient greater than 0.95 is selected as the valid array. This method is used to obtain the fractal dimension value of the fault network in the Huaibei coalfield area, which is between 0.1754 and 1.9221, and the correlation coefficient R of each block is mostly above 0.95.

[0030] Formula (1):

[0031] S3. Determine the fractal level. Combined with the characteristics of the obtained data, analyze its maximum, minimum and average values, and divide its level standards into four levels: simple, medium, relatively complex, and complex, that is, Ds<0.908, 0.908≤Ds<1.049, 1.049≤Ds≤1.193, Ds≥1.193. Figure 4 Table of contents.

[0032] The quantitative partitioning includes: using the determined fractal dimension value Ds, using suffer to partition the Ds value according to the determined fractal dimension threshold, obtaining the fractal dimension (similarity dimension) map of the Huaibei coalfield fracture, and superimposing the structural trace map on this basis to achieve quantitative partitioning according to the fractal dimension value, such as Figure 6 shown.

[0033] The water richness of loose layers under different fault complexity, including the acquisition of unit water yield value of loose layers and the comparison of water richness per unit water yield.

[0034] S1. Obtain the unit water inflow value of the loose layer and find representative mining areas under different structural levels on the Huaibei fractal quantitative zoning map. Figure 7 As shown, such as Qidong Mine (complex), Wobei (relatively complex), Renlou (relatively complex), Qingdong (medium). Water extraction tests were conducted on representative mining areas of different levels, and data from the same aquifer in different mines were used for comparison. The water inflow Q and stable drawdown S of the loose layer of each mine were recorded. The unit water inflow calculation formula (2) was used to obtain the q value. A table of unit water inflow of the loose layer of mining areas with different structural complexity levels was obtained, as shown in the figure below: Figure 5 As shown in the table,

[0035] Formula (2):

[0036] S2. Comparison of unit water yield: According to the unit water yield of representative mining areas at different levels obtained in the first step, a horizontal comparison is made, and a bar chart is drawn to determine the level corresponding to the unit water yield value under the complex, medium, simple and other structural classifications. Figure 3 As shown in the figure, the level of water inflow is determined according to the "Detailed Rules for Mine Water Control", so as to judge the control of structural complexity on the water-richness of the loose layer. Figure 3 As shown, Qidong Mine belongs to a complex fault structure area, with a maximum unit water inflow of 0.410 l / s·m, a minimum of 0.036 l / s·m, and an average of 0.269 l / s·m. The loose layer is moderately water-rich. Wobei Mine belongs to an area with relatively complex fault structure, with a maximum unit water inflow of 0.05318 l / s·m, a minimum of 0.00017 l / s·m and an average of 0.0199 l / s·m. The loose layer is weakly water-rich. Renlou Mine belongs to an area with relatively complex fault structure, with a maximum unit water inflow of 0.058 l / s·m, a minimum of 0.000325 l / s·m and an average of 0.0128 l / s·m. The loose layer is weakly water-rich. Qingdong Mine belongs to an area with moderately complex fault structure, with a maximum unit water inflow of 0.037 l / s·m, a minimum of 0.00033 l / s·m and an average of 0.0135 l / s·m. The loose layer is weakly water-rich. Generally speaking, the higher the degree of fault development in Qidong Mine, the more conducive it is to the gathering of loose layer water, and its water richness is much higher than that of Renlou Mine and Wobei Mine. Wobei Mine and Renlou Mine belong to more complex areas, and their water-richness is higher than that of Qingdong Mine. The fault structure has a significant control effect on the water-richness of the loose layer.

[0037] When using it, the fracture fractal method is first used to quantitatively partition the complexity of the fractures that affect coal mining under the loose layer, which can be divided into simple, medium, complex, and relatively complex. Secondly, the correlation analysis of the water richness controlled by the four different degrees of fracture development is carried out. Finally, it is shown that the complex-complex fracture area is conducive to the collection of water by the underground aquifer, and there is a positive correlation between the structural complexity and the water richness of the loose layer. The obtained fracture structure has an obvious control law on the water richness of the loose layer. The field personnel can use this law to reasonably arrange the hydrological control project under the loose layer. This method is easy to understand, and the indicators are easy to obtain, which is convenient for on-site application practice.

[0038] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0039] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A method for determining the water richness of a loose aquifer controlled by a fracture structure, characterized in that: It includes quantitative zoning of fault complexity and comparison of water-richness of loose layers under different fault complexity, wherein the quantitative zoning of fault complexity includes obtaining fractal dimension value grades and fractal dimension value quantitative zoning; The fractal dimension value quantitative partitioning includes: using a determined fractal dimension value Ds, using suffer to partition the Ds value according to a determined fractal dimension threshold, obtaining a fracture fractal dimension map, superimposing a structural outline map on this basis, and realizing quantitative partitioning according to the fractal dimension value, the water-richness of the loose layer under different fault complexity, including the acquisition of the unit water yield value of the loose layer and the comparison of the unit water yield, which includes the following steps: S1, the unit water inflow value of the loose layer is obtained. The representative mining areas under different structural levels are found on the fractal quantitative zoning map. The pumping test is carried out on the representative mining areas under different levels. The data of the same aquifer in different mines are used for comparison. The water inflow Q and stable drawdown S of the loose layer water inflow test data of each mine are recorded. The unit water inflow calculation formula (2) is used to obtain the q value. Formula (2): (2) S2. Comparison of water-richness per unit yield. A horizontal comparison of the unit yields of representative mining areas at different levels obtained in S1 is made, and a bar graph is drawn to determine the level corresponding to the unit yield values ​​under the structural complexity, medium, and simple levels, thereby determining the control of structural complexity on the water-richness of the loose layer. Areas with a higher degree of fault development, that is, areas with more complex fault structures, are conducive to the collection of water by underground aquifers. Generally, there is a positive correlation between the water-richness of the rock layer and the higher the structural complexity, that is, the higher the complexity, the stronger the water-richness.

2. According to the method for determining the water-richness of a loose aquifer controlled by a fracture structure as described in claim 1, the step of obtaining the fractal dimension value level comprises the following steps: S1. Get the box dimension After clarifying the scope of the study area, the grid covering method is used for the regional structural traces. On the standard grid, according to the set grid side length Record the number of grids with fracture traces of corresponding side lengths in sequence, where : initial mesh edge length; : box dimension; S2, calculate the fractal dimension value Ds, and use the linear regression method to lgN( ) and lg( ) to conduct correlation analysis, the fractal dimension value Ds is calculated according to formula (1), and the Ds value with a correlation coefficient greater than 0.95 is selected as the valid array. Formula (1): (1) S3. Determine the dimensionality level. Combine the characteristics of the obtained Ds data, analyze its maximum, minimum and average values, determine the level threshold, and divide its level standards into four levels: simple, medium, relatively complex, and complex.

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