Calculation method and system for water storage coefficient of underground water reservoir in coal mines

Abstract

The present invention provides a method and system for calculating the water storage coefficient of a coal mine underground reservoir. The method includes: determining a preset area of ​​the coal mine underground reservoir bottom plate; obtaining the pressure in a sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping at the preset area of ​​the coal mine underground reservoir bottom plate; pumping the coal mine underground reservoir and obtaining the pressure in a sensing water tank after pumping, the water head height of the reservoir after pumping, and the internal air pressure of the reservoir after pumping at the preset area of ​​the reservoir bottom plate after the water level stabilizes; and calculating the water storage coefficient of the coal mine underground reservoir based on a stress balance formula at the preset area before pumping, a stress balance formula at the preset area after pumping, and influencing parameters. The present invention solves the technical problem of errors in the calculated water storage coefficient caused by methods other than direct measurement in the prior art by performing on-site measurements of reservoir bottom plate stress, water head, and air pressure, and calculating the water storage coefficient based on the stress balance equation.

Description

Technical Field

[0001] The present invention relates to the field of coal mines, and in particular to a method and system for calculating the water storage coefficient of underground water reservoirs in coal mines. Background Art

[0002] During coal mining, it is necessary to obtain the water storage coefficient of the coal mine underground reservoir to ensure mining. The current problem encountered in the on-site measurement of the water storage coefficient of the coal mine underground reservoir is that the coal mine underground reservoir is in a completely enclosed underground space. In the existing technology, many methods for calculating the water storage coefficient of the coal mine underground reservoir are not direct measurements, but through laboratory physical similarity simulation tests or numerical simulation calculations. However, the above two simulation methods are different from the actual situation on site, so the water storage coefficient obtained has errors and is inaccurate. Summary of the Invention

[0003] Based on the above problems, the present invention proposes a method and system for calculating the water storage coefficient of underground water reservoirs in coal mines. By performing on-site measurements of the reservoir bottom plate stress, head, and air pressure and calculating the water storage coefficient in combination with the stress balance equation, the present invention solves the technical problem in the existing technology that the water storage coefficient is calculated with errors by laboratory physical similarity simulation tests or numerical simulation calculations instead of direct measurements.

[0004] The present invention proposes a method for calculating the water storage coefficient of a coal mine underground reservoir, comprising:

[0005] Determine the preset area of ​​the bottom slab of the coal mine underground water reservoir;

[0006] Obtain the pressure inside the sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping at a preset area of ​​the bottom plate of the coal mine underground water reservoir;

[0007] Pump water from the underground reservoir of the coal mine and obtain the pressure inside the sensing tank after pumping, the water head height of the reservoir after pumping, and the internal air pressure of the reservoir after pumping at a preset area of ​​the reservoir bottom plate after the water level stabilizes;

[0008] The water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters. The influencing parameters include at least: the volume of rock below the water table directly above the preset area, the volume of invalid pores below the water table directly above the preset area, and the mass of rock directly above the preset area.

[0009] In addition, the stress balance formula at the preset area before pumping is:

[0010] P1A=M 岩 g+ρ 水 gh1A+P 气1 A-ρ 水 g(V 岩1 +V无效空隙1 ),

[0011] The stress balance formula at the preset area after pumping is:

[0012] P2A=M 岩 g+ρ 水 gh2A+P 气2 A-ρ 水 g(V 岩2 +V 无效空隙2 ),

[0013] Where: A is the preset area, P1 and P2 are the pressures in the sensing tank before and after pumping; h1 and h2 are the water head heights of the reservoir before and after pumping; P 气1 、P 气2 V is the internal pressure of the reservoir before and after pumping; 岩1 、V 岩2 V is the volume of rock below the water table directly above the preset area before and after pumping; 无效孔隙1 、V 无效孔隙2 M is the volume of ineffective pore space below the water table just above the preset area before and after pumping; 岩 is the mass of rock directly above the preset area; ρ 水 is the density of reservoir water; g is the acceleration due to gravity.

[0014] In addition, according to the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping and the influencing parameters, the water storage coefficient of the coal mine underground reservoir is calculated as follows:

[0015] After subtracting the stress smoothing formula at the preset area before pumping and the stress smoothing formula at the preset area after pumping, the drainage volume corresponding to the preset area is obtained.

[0016] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ),

[0017]

[0018] In addition, the calculation formula for the water storage coefficient R of the coal mine underground reservoir is:

[0019]

[0020] According to the calculated drainage volume corresponding to the preset area

[0021] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 )

[0022] And the total volume corresponding to the preset area

[0023] A(h1-h2)

[0024] Calculate the value of R.

[0025] The present invention also provides a coal mine underground water reservoir water storage coefficient calculation system, comprising:

[0026] Induction water tank, water pipe, water filling and draining valve, external water tank, water pressure gauge, water level gauge, processor and air pressure gauge;

[0027] The two ends of the water pipe are connected to the sensing water tank and the external water tank respectively. The water filling and discharge valves are installed on the water pipe. The water pressure gauge, water level gauge and air pressure gauge are connected to the processor respectively. The water pressure gauge is placed inside the external water tank to test the water pressure inside the external water tank. The water level gauge is placed near the bottom plate of the reservoir. The air pressure gauge is placed in the upper half of the reservoir. The water level gauge and air pressure gauge test the height of the reservoir and the air pressure inside the reservoir respectively. The pressure inside the sensing water tank is calculated based on the data measured by the stress sensing water tank, the external water tank and the water pressure gauge.

[0028] The calculation method of the water storage coefficient of the coal mine underground reservoir is as follows:

[0029] Determine the preset area of ​​the bottom slab of the coal mine underground water reservoir;

[0030] Obtain the pressure inside the sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping at a preset area of ​​the bottom plate of the coal mine underground water reservoir;

[0031] Pump water from the underground reservoir of the coal mine and obtain the pressure inside the sensing tank after pumping, the water head height of the reservoir after pumping, and the internal air pressure of the reservoir after pumping at a preset area of ​​the reservoir bottom plate after the water level stabilizes;

[0032] The water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters. The influencing parameters include at least: the volume of rock below the water table directly above the preset area, the volume of invalid pores below the water table directly above the preset area, and the mass of rock directly above the preset area.

[0033] In addition, the water level meter is MinDiver.

[0034] In addition, the barometer is Bivo.

[0035] In addition, the stress balance formula at the preset area before pumping is:

[0036] P1A=M 岩 g+ρ 水 gh1A+P 气1 A-ρ 水 g(V 岩1 +V无效空隙1 ),

[0037] The stress balance formula at the preset area after pumping is:

[0038] P2A=M 岩 g+ρ 水 gh2A+P 气2 A-ρ 水 g(V 岩2 +V 无效空隙2 ),

[0039] Where: A is the preset area, P1 and P2 are the pressures in the sensing tank before and after pumping; h1 and h2 are the water head heights of the reservoir before and after pumping; P 气1 、P 气2 V is the internal pressure of the reservoir before and after pumping; 岩1 、V 岩2 V is the volume of rock below the water table directly above the preset area before and after pumping; 无效孔隙1 、V 无效孔隙2 M is the volume of ineffective pore space below the water table just above the preset area before and after pumping; 岩 is the mass of rock directly above the preset area; ρ 水 is the density of reservoir water; g is the acceleration due to gravity.

[0040] In addition, according to the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping and the influencing parameters, the water storage coefficient of the coal mine underground reservoir is calculated as follows:

[0041] After subtracting the stress smoothing formula at the preset area before pumping and the stress smoothing formula at the preset area after pumping, the drainage volume corresponding to the preset area is obtained.

[0042] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ),

[0043]

[0044] In addition, the calculation formula for the water storage coefficient R of the coal mine underground reservoir is:

[0045]

[0046] According to the calculated drainage volume corresponding to the preset area

[0047] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 )

[0048] And the total volume corresponding to the preset area

[0049] A(h1-h2)

[0050] Calculate the value of R.

[0051] By adopting the above technical solution, the following beneficial effects are achieved:

[0052] The present invention solves the technical problem in the prior art that the calculated water storage coefficient has errors due to laboratory physical similarity simulation tests or numerical simulation calculations instead of direct measurements by performing on-site measurements of the reservoir bottom plate stress, water head and air pressure and calculating the water storage coefficient in combination with the stress balance equation.

[0053] The present invention solves the technical problem of calculating the local water storage coefficient of a coal mine underground water reservoir in the prior art. The current on-site measurement method of the reservoir water storage coefficient can calculate the water storage coefficient of different vertical layers and the average permeability coefficient of the entire reservoir, but cannot calculate the water storage coefficient of a certain point in the reservoir. The present invention controls the horizontal position by presetting an area in the reservoir and then controls the vertical height of the water by pumping water, so that the water storage coefficient of a certain point in the three-dimensional space of the reservoir can be calculated.

[0054] The present invention avoids errors caused by invalid pores and bound water by introducing the concept of V invalid pore volume into the stress balance equation.

[0055] The air pressure in the goaf above the water table of the reservoir will also change with weather, climate and other factors. The water storage coefficient calculation methods in the existing technology all take this factor into consideration. The present invention avoids the calculation error caused by the change of the internal air pressure of the reservoir by adding the internal air pressure parameter of the reservoir to the stress smoothing formula. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is a flow chart of a method for calculating the water storage coefficient of a coal mine underground reservoir provided by one embodiment of the present invention;

[0057] Figure 2 It is a schematic diagram of a coal mine underground water reservoir water storage coefficient calculation system provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0058] The present invention is further described in detail below with reference to specific embodiments and accompanying drawings, which are intended only to elaborate on the specific embodiments of the present invention and do not impose any limitation on the present invention. The scope of protection of the present invention shall be subject to the claims.

[0059] Reference Figure 1 The present invention proposes a method for calculating the water storage coefficient of a coal mine underground reservoir, comprising:

[0060] Step S001, determining a preset area of ​​the bottom plate of the coal mine underground reservoir;

[0061] Step S002, obtaining the pressure in the sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping at a preset area of ​​the bottom plate of the coal mine underground water reservoir;

[0062] Step S003: pumping water from the underground reservoir of the coal mine, and obtaining the pressure inside the sensing water tank after pumping, the water head height of the reservoir after pumping, and the air pressure inside the reservoir after pumping at a preset area of ​​the reservoir bottom plate after the water level stabilizes;

[0063] Step S004, the water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters, where the influencing parameters include at least: the volume of rock below the water table directly above the preset area, the volume of invalid pores below the water table directly above the preset area, and the mass of rock directly above the preset area.

[0064] There are several methods for determining the water storage coefficient of underground water reservoirs in coal mines in the prior art, such as:

[0065] 1) A method and electronic equipment for determining the water storage coefficient of a coal mine underground reservoir: obtaining the mining height, advancement length, thickness of each roof rock layer, collapse angle of each roof rock layer, crushing expansion coefficient of each roof rock layer, original porosity and fracture degree of each roof rock layer, and initial volume of each roof rock layer of the coal mine underground reservoir to be measured; determining the collapsed space volume of the roof rock layer after coal seam excavation based on the mining height, advancement length, thickness of each roof rock layer, and collapse angle of each roof rock layer; determining the water storage coefficient of the coal mine underground reservoir to be measured based on the thickness of each roof rock layer, crushing expansion coefficient of each roof rock layer, original porosity and fracture degree of each roof rock layer, initial volume of each roof rock layer, and collapse space volume of the roof rock layer.

[0066] This invention can infer the average water storage coefficient of the coal mine underground water reservoir through the state before mining collapse, but it has the following shortcomings: First, it assumes that all pores will be filled with water under the default water level. According to hydrogeology, porosity and effective porosity are two concepts. Not all pores in the rock mass will be filled with water, so the calculated water storage coefficient is too large; second, after the rock is soaked in water, bound water will form on the rock surface, and the water molecular structure is combined with the rock molecules. This part of water cannot be discharged from the reservoir again, resulting in the calculated water storage coefficient being too large.

[0067] 2) A method for determining the water storage coefficient of an underground water reservoir in a coal mine: establishing a three-dimensional similarity test model of a mine to be measured, the three-dimensional similarity test model including an overlying rock layer, an aquifer, an impermeable layer, an underground water reservoir rock layer and a floor rock layer arranged in sequence from top to bottom; performing working face coal seam excavation on the three-dimensional similarity test model; performing water injection and water discharge tests on the three-dimensional similarity test model to obtain the amount of water discharged per unit height drop in the water level of the underground water reservoir rock layer; determining the water-containing volume corresponding to each unit height of the underground water reservoir rock layer; determining the water storage coefficient corresponding to each unit height based on the water-containing volume corresponding to each unit height of the underground water reservoir rock layer and the water discharge corresponding to each unit height drop in the water level of the underground water reservoir rock layer.

[0068] This invention can calculate the average water storage coefficient of the coal mine underground water reservoir and the water storage coefficient of each layer through precipitation tests, but has the following shortcomings: First, from the perspective of the reservoir as a whole, the reservoir bottom plate is not necessarily horizontal, the reservoir boundary is irregular, and the water area of ​​the reservoir at different water levels is different, which will cause errors in calculating the water volume of the reservoir; secondly, due to the large area of ​​the reservoir, when the reservoir is pumped to lower the water level, the water surface inside the reservoir is not a plane, but forms a funnel shape with the pumping pipe as the lowest point, so there are errors in the calculation of the total volume and the volume of water; finally, there are differences between the data measured through similar tests and the data directly measured on site, and the errors are relatively large.

[0069] 3) A device for measuring the water storage coefficient of underground water reservoirs in coal mines: comprising a test box containing a rock mass of similar simulated material, one side of the test box connected to a water supply pipe and the other side connected to a water outlet pipe, the water supply pipe being connected to a water storage tank, the water supply pipe being provided with an electrically controlled automatic water stop valve, the outlet pipe being connected to a water storage capacity monitoring device, a pressure plate being placed on top of the test box, a pressure rod being connected to the pressure plate, the pressure rod being hinged to a lever, one end of the lever being hinged to a support frame above the test box, the other end being connected to a pressure device, the pressure device being provided with a pressure monitoring device, the support frame being provided with a displacement monitoring device for monitoring the displacement of the pressure plate, the electrically controlled automatic water stop valve, the water storage capacity monitoring device, the pressure monitoring device, and the displacement monitoring device being all connected to a computer. The device can realistically simulate the roof pressure environment of a water storage goaf area and measure the water storage coefficient under the action of the roof pressure.

[0070] This invention calculates the water storage coefficient through simulation test, but cannot directly measure the water storage coefficient of underground water reservoir in coal mines, and there is a large error.

[0071] In step S001 of the method for calculating the water storage coefficient of a coal mine underground reservoir proposed by the present invention, a preset area of ​​the bottom plate of the coal mine underground reservoir is determined; the bottom plate, the water table, and the surrounding boundaries of the coal mine underground reservoir cannot be determined to be horizontal or regular shapes. Many water storage coefficient calculation methods ignore this feature and lead to calculation errors. The present invention solves the technical problem of calculation errors caused by changes in reservoir area at different heights and non-horizontal water table by introducing the preset area of ​​the bottom plate of the coal mine underground reservoir.

[0072] In step S002, the pressure in the sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping are obtained at a preset area of ​​the bottom plate of the coal mine underground reservoir; and the data of the coal mine underground reservoir before pumping are obtained.

[0073] In step S003, the coal mine underground reservoir is pumped to obtain the post-pumping pressure in the sensing tank, the water head height, and the internal pressure of the reservoir at a predetermined area on the reservoir floor after the water level stabilizes. The post-pumping data is then used to calculate the discharge volume corresponding to the predetermined area.

[0074] Step S004 calculates the water storage coefficient of the coal mine underground reservoir based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and influencing parameters. The influencing parameters include at least the volume of rock below the water table directly above the preset area, the volume of ineffective pores below the water table directly above the preset area, and the mass of rock directly above the preset area. By introducing the ineffective pore volume into the stress balance formula (equation), errors caused by ineffective pores and bound water are avoided. This invention avoids errors caused by irregularities in the overall shape of the reservoir by using the preset area, and can measure the water storage coefficient at a specific point in the reservoir's three-dimensional space.

[0075] The present invention solves the technical problem in the prior art that the calculated water storage coefficient has errors due to laboratory physical similarity simulation tests or numerical simulation calculations instead of direct measurements by performing on-site measurements of the reservoir bottom plate stress, water head and air pressure and calculating the water storage coefficient in combination with the stress balance equation.

[0076] The present invention solves the technical problem of calculating the local water storage coefficient of a coal mine underground water reservoir in the prior art. The current on-site measurement method of the reservoir water storage coefficient can calculate the water storage coefficient of different vertical layers and the average permeability coefficient of the entire reservoir, but cannot calculate the water storage coefficient of a certain point in the reservoir. The present invention controls the horizontal position by presetting an area in the reservoir and then controls the vertical height of the water by pumping water, so that the water storage coefficient of a certain point in the three-dimensional space of the reservoir can be calculated.

[0077] The present invention avoids errors caused by invalid pores and bound water by introducing the concept of V invalid pore volume into the stress balance equation.

[0078] The air pressure in the goaf above the water table of the reservoir will also change with weather, climate and other factors. The water storage coefficient calculation methods in the existing technology all take this factor into consideration. The present invention avoids the calculation error caused by the change of the internal air pressure of the reservoir by adding the internal air pressure parameter of the reservoir to the stress smoothing formula.

[0079] In one embodiment, the stress balance formula at the preset area before pumping is:

[0080] P1A=M 岩 g+ρ 水 gh1A+P 气1 A-ρ 水 g(V 岩1 +V 无效空隙1 ),

[0081] The stress balance formula at the preset area after pumping is:

[0082] P2A=M 岩 g+ρ 水 gh2A+P 气2 A-ρ 水 g(V 岩2 +V 无效空隙2 ),

[0083] Where: A is the preset area, P1 and P2 are the pressures in the sensing tank before and after pumping; h1 and h2 are the water head heights of the reservoir before and after pumping; P 气1 、P 气2 V is the internal pressure of the reservoir before and after pumping; 岩1 、V 岩2 V is the volume of rock below the water table directly above the preset area before and after pumping; 无效孔隙1 、V 无效孔隙2 M is the volume of ineffective pore space below the water table just above the preset area before and after pumping; 岩 is the mass of rock directly above the preset area; ρ 水 is the density of reservoir water; g is the acceleration due to gravity.

[0084] This embodiment provides stress balance formulas at a preset area before pumping and stress balance formulas at a preset area after pumping. By introducing parameters such as the preset area, the pressure in the sensing water tank, the water head height of the reservoir, the air pressure inside the reservoir, the volume of rock below the phreatic surface directly above the preset area, and the volume of invalid pores below the phreatic surface directly above the preset area into the formulas, the calculation results are made more accurate and many errors are avoided.

[0085] In one embodiment, the water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters, including:

[0086] After subtracting the stress smoothing formula at the preset area before pumping and the stress smoothing formula at the preset area after pumping, the drainage volume corresponding to the preset area is obtained.

[0087] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ),

[0088]

[0089] Since the drainage volume corresponding to the preset area and the total volume corresponding to the preset area are required when calculating the water storage coefficient of the coal mine underground reservoir, the drainage volume corresponding to the preset area is calculated here first.

[0090] In one embodiment, the calculation formula of the water storage coefficient R of the coal mine underground reservoir is:

[0091]

[0092] According to the calculated drainage volume corresponding to the preset area

[0093] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 )

[0094] And the total volume corresponding to the preset area

[0095] A(h1-h2)

[0096] Calculate the value of R.

[0097] Subtract the drainage volume corresponding to the preset area from 1

[0098] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 )

[0099] Divide by the total volume corresponding to the preset area

[0100] The quotient of A(h1-h2) is used to obtain the water storage coefficient R of the coal mine underground water reservoir. The R value calculated in this way is more accurate and reliable.

[0101] The water storage coefficient R of the coal mine underground reservoir is the water storage coefficient above the preset area and between the height h1ˉh2.

[0102] Reference Figure 2 The present invention proposes a system for calculating the water storage coefficient of a coal mine underground reservoir, comprising:

[0103] Induction water tank 1, water pipe 2, water filling and discharge valve 3, external water tank 4, water pressure gauge 5, water level meter 7, processor 8 and air pressure meter 10;

[0104] The two ends of the water pipe 2 are respectively connected to the induction water tank 1 and the external water tank 4. The water filling and discharge valve 3 is installed on the water pipe 2. The water pressure gauge 5, the water level meter 7 and the barometer 10 are respectively connected to the processor 8. The water pressure gauge 5 is placed inside the external water tank 4 to test the water pressure inside the external water tank 4. The water level meter 7 is placed near the bottom plate of the reservoir. The barometer 10 is placed in the upper half of the reservoir. The water level meter 7 and the barometer 10 respectively test the height of the reservoir and the air pressure inside the reservoir; the pressure inside the induction water tank is calculated based on the data measured by the stress induction water tank 1, the external water tank 4 and the water pressure gauge 5;

[0105] The calculation method of the water storage coefficient of the coal mine underground reservoir is as follows:

[0106] Determine the preset area of ​​the bottom slab of the coal mine underground water reservoir;

[0107] Obtain the pressure inside the sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping at a preset area of ​​the bottom plate of the coal mine underground water reservoir;

[0108] Pump water from the underground reservoir of the coal mine and obtain the pressure inside the sensing tank after pumping, the water head height of the reservoir after pumping, and the internal air pressure of the reservoir after pumping at a preset area of ​​the reservoir bottom plate after the water level stabilizes;

[0109] The water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters. The influencing parameters include at least: the volume of rock below the water table directly above the preset area, the volume of invalid pores below the water table directly above the preset area, and the mass of rock directly above the preset area.

[0110] The reservoir floor's preset area A is equal to the upper area of ​​induction tank 1. The stress on the upper area of ​​induction tank 1 is the internal pressure of the induction tank. This pressure is calculated using data measured by the stress-sensing tank 1, the external tank 4, and the pressure gauge 5. When the external tank 4 and induction tank 1 are at the same altitude, the internal water pressures are the same. At this point, the pressure measured by the pressure gauge 5 represents the stress on the upper area of ​​induction tank 1.

[0111] Optionally, the water pressure gauge 5, the water level gauge 7 and the air pressure gauge 10 are respectively connected to the processor 8 via a data line 6. Optionally, the processor 8 is a computer.

[0112] The present invention solves the technical problem in the prior art that the calculated water storage coefficient has errors due to laboratory physical similarity simulation tests or numerical simulation calculations instead of direct measurements by performing on-site measurements of the reservoir bottom plate stress, water head and air pressure and calculating the water storage coefficient in combination with the stress balance equation.

[0113] The present invention solves the technical problem of calculating the local water storage coefficient of a coal mine underground water reservoir in the prior art. The current on-site measurement method of the reservoir water storage coefficient can calculate the water storage coefficient of different vertical layers and the average permeability coefficient of the entire reservoir, but cannot calculate the water storage coefficient of a certain point in the reservoir. The present invention controls the horizontal position by presetting an area in the reservoir and then controls the vertical height of the water by pumping water, so that the water storage coefficient of a certain point in the three-dimensional space of the reservoir can be calculated.

[0114] The present invention avoids errors caused by invalid pores and bound water by introducing the concept of V invalid pore volume into the stress balance equation.

[0115] The air pressure in the goaf above the water table of the reservoir will also change with weather, climate and other factors. The water storage coefficient calculation methods in the existing technology all take this factor into consideration. The present invention avoids the calculation error caused by the change of the internal air pressure of the reservoir by adding the internal air pressure parameter of the reservoir to the stress smoothing formula.

[0116] In one embodiment, the water level meter 7 is a MinDiver.

[0117] In one embodiment, the barometer 10 is a Bivo, 9 is the reservoir bottom plate, and 11 is the artificial dam body.

[0118] In one embodiment, the stress balance formula at the preset area before pumping is:

[0119] P1A=M 岩 g+ρ 水 gh1A+P 气1 A-ρ 水 g(V 岩1 +V 无效空隙1 ),

[0120] The stress balance formula at the preset area after pumping is:

[0121] P2A=M 岩 g+ρ 水 gh2A+P 气2 A-ρ 水 g(V 岩2 +V 无效空隙2 ),

[0122] Where: A is the preset area, P1 and P2 are the pressures in the sensing tank before and after pumping; h1 and h2 are the water head heights of the reservoir before and after pumping; P 气1 、P 气2 V is the internal pressure of the reservoir before and after pumping; 岩1 、V 岩2 V is the volume of rock below the water table directly above the preset area before and after pumping; 无效孔隙1 、V 无效孔隙2 M is the volume of ineffective pore space below the water table just above the preset area before and after pumping; 岩 is the mass of rock directly above the preset area; ρ 水 is the density of reservoir water; g is the acceleration due to gravity.

[0123] This embodiment provides stress balance formulas at a preset area before pumping and stress balance formulas at a preset area after pumping. By introducing parameters such as the preset area, the pressure in the sensing water tank, the water head height of the reservoir, the air pressure inside the reservoir, the volume of rock below the phreatic surface directly above the preset area, and the volume of invalid pores below the phreatic surface directly above the preset area into the formulas, the calculation results are made more accurate and many errors are avoided.

[0124] In one embodiment, the water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters, including:

[0125] After subtracting the stress smoothing formula at the preset area before pumping and the stress smoothing formula at the preset area after pumping, the drainage volume corresponding to the preset area is obtained.

[0126] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ),

[0127]

[0128] Since the drainage volume corresponding to the preset area and the total volume corresponding to the preset area are required when calculating the water storage coefficient of the coal mine underground reservoir, the drainage volume corresponding to the preset area is calculated here first.

[0129] In one embodiment, the calculation formula of the water storage coefficient R of the coal mine underground reservoir is:

[0130]

[0131] According to the calculated drainage volume corresponding to the preset area

[0132] (V 岩1 +V 无效孔隙1 )-(V岩2 +V 无效孔隙2 )

[0133] And the total volume corresponding to the preset area

[0134] A(h1-h2)

[0135] Calculate the value of R.

[0136] Subtract the drainage volume corresponding to the preset area from 1

[0137] (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 )

[0138] Divide by the total volume corresponding to the preset area

[0139] The quotient of A(h1-h2) is used to obtain the water storage coefficient R of the coal mine underground water reservoir. The R value calculated in this way is more accurate and reliable.

[0140] This embodiment determines the water storage coefficient of the coal mine underground reservoir by presetting the bottom area, obtaining the initial reservoir water level and initial stress of the preset bottom area, performing reservoir dewatering, and obtaining the cutoff reservoir water level and stress of the preset bottom area. The amount of water released corresponding to the preset area is calculated based on the initial and post-dewatering stress balance equations. The total volume corresponding to the preset area is calculated using the water levels before and after dewatering and the preset area, thereby determining the water storage coefficient of the coal mine underground reservoir. This embodiment avoids errors caused by ineffective pores and irregular reservoir bottom areas, enables reasonable measurement of the effective water storage coefficient of the underground reservoir, and guides the calculation of underground reservoir capacity and the optimized design of artificial dam structures.

[0141] The above description is only the principle and preferred embodiment of the present invention. It should be noted that for those skilled in the art, several other variations can be made based on the principle of the present invention, which should also be considered as the scope of protection of the present invention.

Claims

1. A method for calculating the water storage coefficient of a coal mine underground reservoir, characterized in that: include: Determine the preset area of ​​the bottom slab of the coal mine underground water reservoir; Obtain the pressure inside the sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping at a preset area of ​​the bottom plate of the coal mine underground water reservoir; Pump water from the underground reservoir of the coal mine and obtain the pressure inside the sensing tank after pumping, the water head height of the reservoir after pumping, and the internal air pressure of the reservoir after pumping at a preset area of ​​the reservoir bottom plate after the water level stabilizes; The water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters, wherein the influencing parameters include at least: the volume of rock below the water table directly above the preset area, the volume of ineffective pores below the water table directly above the preset area, and the mass of rock directly above the preset area; The stress balance formula at the preset area before pumping is: P1A6M 岩 g+ρ 水 gh1A+P 气1 A-ρ 水 g(V 岩1 +V 无效空隙1 ), The stress balance formula at the preset area after pumping is: P2A / M 岩 g+ρ 水 gh2A+P 气2 A-ρ 水 g(V 岩2 +V 无效空隙2 ), Where: A is the preset area, P1 and P2 are the pressures in the sensing tank before and after pumping; h1 and h2 are the water head heights of the reservoir before and after pumping; P 气1 、P 气2 V is the internal pressure of the reservoir before and after pumping; 岩1 、V 岩2 V is the volume of rock below the water table directly above the preset area before and after pumping; 无效孔隙1 、V 无效孔隙2 M is the volume of ineffective pore space below the water table just above the preset area before and after pumping; 岩 is the mass of rock directly above the preset area; ρ 水 is the density of reservoir water; g is the acceleration due to gravity; The water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters, including: After subtracting the stress smoothing formula at the preset area before pumping and the stress smoothing formula at the preset area after pumping, the drainage volume corresponding to the preset area is obtained. (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ), The calculation formula for the water storage coefficient R of the coal mine underground reservoir is: According to the calculated drainage volume corresponding to the preset area (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ) And the total volume corresponding to the preset area A(h1-h2) Calculate the value of R.

2. A coal mine underground reservoir water storage coefficient calculation system, characterized in that: include: Induction water tank, water pipe, water filling and draining valve, external water tank, water pressure gauge, water level gauge, processor and air pressure gauge; The two ends of the water pipe are connected to the induction water tank and the external water tank respectively. The water filling and discharge valves are installed on the water pipe. The water pressure gauge, water level gauge and air pressure gauge are connected to the processor respectively. The water pressure gauge is placed inside the external water tank to test the water pressure inside the external water tank. The water level gauge is placed near the bottom plate of the reservoir. The air pressure gauge is placed in the upper half of the reservoir. The water level gauge and air pressure gauge test the height of the reservoir and the air pressure inside the reservoir respectively. The pressure inside the sensing water tank is calculated by using the data measured by the stress sensing water tank, the external water tank and the water pressure gauge; The calculation method of the water storage coefficient of the coal mine underground reservoir is as follows: Determine the preset area of ​​the bottom slab of the coal mine underground water reservoir; Obtain the pressure inside the sensing water tank before pumping, the water head height of the reservoir before pumping, and the internal air pressure of the reservoir before pumping at a preset area of ​​the bottom plate of the coal mine underground water reservoir; Pump water from the underground reservoir of the coal mine and obtain the pressure inside the sensing tank after pumping, the water head height of the reservoir after pumping, and the internal air pressure of the reservoir after pumping at a preset area of ​​the reservoir bottom plate after the water level stabilizes; The water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters, wherein the influencing parameters include at least: the volume of rock below the water table directly above the preset area, the volume of ineffective pores below the water table directly above the preset area, and the mass of rock directly above the preset area; The stress balance formula at the preset area before pumping is: P1A6M 岩 g+ρ 水 gh1A+P 气1 A-ρ 水 g(V 岩1 +V 无效空隙1 ), The stress balance formula at the preset area after pumping is: P2A / M 岩 g+ρ 水 gh2A+P 气2 A-ρ 水 g(V 岩2 +V 无效空隙2 ), Where: A is the preset area, P1 and P2 are the pressures in the sensing tank before and after pumping; h1 and h2 are the water head heights of the reservoir before and after pumping; P 气1 、P 气2 V is the internal pressure of the reservoir before and after pumping; 岩1 、V 岩2 V is the volume of rock below the water table directly above the preset area before and after pumping; 无效孔隙1 、V 无效孔隙2 M is the volume of ineffective pore space below the water table just above the preset area before and after pumping; 岩 is the mass of rock directly above the preset area; ρ 水 is the density of reservoir water; g is the acceleration due to gravity; The water storage coefficient of the coal mine underground reservoir is calculated based on the stress balance formula at the preset area before pumping, the stress balance formula at the preset area after pumping, and the influencing parameters, including: After subtracting the stress smoothing formula at the preset area before pumping and the stress smoothing formula at the preset area after pumping, the drainage volume corresponding to the preset area is obtained. (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ), The calculation formula for the water storage coefficient R of the coal mine underground reservoir is: According to the calculated drainage volume corresponding to the preset area (V 岩1 +V 无效孔隙1 )-(V 岩2 +V 无效孔隙2 ) And the total volume corresponding to the preset area A(h1-h2) Calculate the value of R.

3. The coal mine underground reservoir water storage coefficient calculation system according to claim 2, characterized in that: The water level meter is MinDiver.

4. The coal mine underground reservoir water storage coefficient calculation system according to claim 2, characterized in that: The barometer is Bivo.

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