A method for obtaining process parameters of deep well recharge of coal mine water

Abstract

The application discloses a kind of coal mine well water deep well recharging process parameter acquisition methods, S1, determine recharging target layer: determine the permeability coefficient K of single sandstone aquifer and single aquifer thickness m;According to the size of the single sandstone aquifer transmissivity T, determine the recharging target layer, S2, determine the type of recharging well and its corresponding process parameters: S3, construction recharging well, obtain long-term stable recharging flow Q L : carry out variable flow field water injection test, continuously observe the injection pump pressure gauge during injection operation, determine the suitable long-term stable recharging flow Q L According to the method, large-flow long-time stable recharging can be realized, the efficiency of deep well recharging is improved, and the treatment cost of high-salt high-fluorine mine water is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of coal mine water protection and relates to a method for obtaining process parameters of deep well reinjection of coal mine water. Background Technology

[0002] As coal resource development shifts to deeper levels, the amount of mine water with high mineralization and containing special components (especially fluoride) will continue to increase. With increasingly stringent zero-discharge policies for mine water, surface treatment of high-mineralization, high-fluoride mine water will generate environmentally harmful solid waste and easily cause secondary pollution. Correspondingly, deep well reinjection technology utilizes the isolation and sealing effects of geological barriers to keep the treatment and disposal sites for high-mineralization and high-fluoride mine water far from the biosphere, thereby achieving long-term, safe, and environmentally friendly results. Deep well reinjection is widely used as a versatile, safe, economical, and efficient method. However, its process parameter design lacks scientific basis, therefore, there is an urgent need for a method for designing process parameters for deep well reinjection of coal mine water. Summary of the Invention

[0003] The purpose of this invention is to provide a method for obtaining process parameters of deep well reinjection of coal mine water. This method can achieve stable reinjection of large flow rates over long periods, improve the efficiency of deep well reinjection, and thus significantly reduce the treatment cost of high-salt and high-fluoride mine water.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for obtaining process parameters of deep well reinjection of coal mine water includes:

[0006] S1. Determine the target layer for reinjection: Determine the permeability coefficient K of a single sandstone aquifer. d And thickness m; the target layer for recharge is determined based on the magnitude of the hydraulic conductivity T of a single sandstone aquifer, and the sandstone aquifer with the highest hydraulic conductivity is the target layer for recharge; where:

[0007] T=K d m;

[0008] S2. Determine the well type and corresponding process parameters of the reinjection well: Based on the geological parameters of the target reinjection layer, numerical simulation is used to investigate the variation of reinjection flow rate Q and diffusion pressure p under different well types, lengths, and injection pressures. The geological parameters of the target reinjection layer include: porosity, permeability coefficient, confined head, and thickness. The larger the reinjection flow rate per unit diffusion pressure, the more optimal the corresponding reinjection well type and process parameters are, thus determining the well type and corresponding process parameters of the reinjection well.

[0009] S3. Construct a reinjection well to obtain a long-term stable reinjection flow rate Q. L: developing variable flow field water injection test, continuously observing the injection pump pressure during injection operation, and determining the suitable long-term stable injection flow Q according to the change of the injection pump pressure L .

[0010] Optionally, the long-term stable injection flow Q L is determined according to the relationship between the injection pump pressure P s and the rated pump pressure of the injection pump:

[0011]

[0012] In the formula, λ is the friction coefficient, L p is the length of the injection well, m; g is the acceleration of gravity, H is the burial depth of the injection target layer; h0 is the confined water head of the injection target layer; γ is the unit weight of water; K is the permeability coefficient of the injection target layer; M is the thickness of the injection target layer; R is the influence radius of the injection target layer; and r is the inner diameter of the injection well in the injection target layer, mm.

[0013] Optionally, the well type includes a straight well, a horizontal well and a cluster branch well.

[0014] Optionally, the process parameters of the straight well include the well diameter and the well length; the process parameters of the horizontal well include the well diameter and the length of the horizontal section; and the process parameters of the cluster branch well include the number of the cluster branch wells, the length of the cluster branch wells and the angle of the cluster branch wells.

[0015] A coal mine well water deep well injection process parameter acquisition method, comprising:

[0016] Step one, first investigate the regional injection stratum parameters, including drilling and comprehensive logging, interpreting the distribution of the aquifer and the aquiclude of the injection well stratum, and the stratum lithology, burial depth, thickness and porosity;

[0017] Step two, developing unsteady flow pumping test, determining the permeability coefficient, confined water head, thickness m and influence radius of the single-layer sandstone aquifer; according to the size of the single-layer sandstone aquifer water conductivity T, determining the injection target layer, and the sandstone aquifer with the largest water conductivity is the injection target layer, wherein:

[0018] T = K d m;

[0019] In the formula, K d is the permeability coefficient of the single-layer sandstone aquifer, and m is the thickness of the single-layer aquifer;

[0020] Step three: based on the geological parameters of the recharging target layer, the variation law of recharging flow Q and diffusion pressure p under the action of different well types, lengths and different injection pressures is carried out by using numerical simulation means, the geological parameters of the recharging target layer include: the porosity, the permeability coefficient, the pressure-bearing water head and the aquifer thickness M of the recharging target layer; the greater the recharging flow per unit diffusion pressure, the more optimal the corresponding recharging well type and process parameters are, so as to determine the well type of the recharging well and the corresponding process parameters;

[0021] Step four: the recharging well is constructed according to the well type of the recharging well and the corresponding process parameters determined in step three;

[0022] Step five: a variable flow field injection test is carried out, the recharging pump pressure during the recharging operation is continuously observed, and the long-term stable recharging flow Q is determined according to the change of the recharging pump pressure L ;

[0023] The relationship between the long-term stable recharging flow Q L and the rated pump pressure P s of the recharging pump is:

[0024]

[0025] In the formula: λ is the friction coefficient, L p is the length of the recharging well, m; g is the acceleration of gravity, H is the burial depth of the recharging target layer; h0 is the pressure-bearing water head of the recharging target layer; γ is the unit weight of water; K is the permeability coefficient of the recharging target layer; M is the thickness of the recharging target layer; R is the influence radius of the recharging target layer; and r is the inner diameter of the recharging well in the recharging target layer, mm.

[0026] Optionally, the well type includes a straight well, a horizontal well and a cluster branch well.

[0027] Optionally, the process parameters of the straight well include a well diameter and a well length; the process parameters of the horizontal well include a well diameter and the length of a horizontal section; and the process parameters of the cluster branch well include the number of cluster branch wells, the length of the cluster branch wells and the angle of the cluster branch wells.

[0028] The beneficial effects of the present application are:

[0029] By optimizing the recharging layer position and optimizing the well type and arrangement, the long-term recharging is finally kept in a high-flow and low-pressure state, the recharging efficiency is improved, and the treatment cost of high-salt and high-fluorine mine water is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings are included to provide a further understanding of the present disclosure and constitute a part of the specification, and together with the specific embodiments below, serve to explain the present disclosure but do not constitute a limitation on the present disclosure. In the drawings:

[0031] Fig. 1 is a different angle of the present application cluster branch well recharge flow variation diagram;

[0032] Fig. 2 is a different angle of the present application cluster branch well recharge diffusion pressure schematic diagram;

[0033] The present application will be described in detail below in conjunction with the drawings and specific embodiments. Specific embodiments

[0034] In accordance with the above technical solution, the following specific embodiments of the present application are given, it should be noted that the present application is not limited to the following specific embodiments, any equivalent transformation based on the technical solution of the present application falls within the scope of the present application.

[0035] The technical terms involved in the present application are explained as follows:

[0036] Long-term stable recharge flow Q L : refers to the maximum flow under long-term stable water injection of the water injection pump under the rated pump pressure.

[0037] The coal mine water deep well recharge process parameter acquisition method of the present application comprises:

[0038] S1, determine the recharge target layer: determine the burial depth, porosity, permeability coefficient K d , confined water head, thickness m and influence radius of single-layer sandstone aquifer; determine the recharge target layer according to the size of the single-layer sandstone aquifer transmissibility coefficient T, the sandstone aquifer with the largest transmissibility coefficient is the recharge target layer; wherein:

[0039] T = K d m;

[0040] In the formula: K d is the permeability coefficient of single-layer rock, m is the thickness of single-layer aquifer;

[0041] S2, determine the well type and corresponding process parameters of the recharge well: based on the geological parameters of the recharge target layer, use numerical simulation means to carry out the variation law of recharge flow Q and diffusion pressure p under the action of different well types, lengths and different water injection pressures, the geological parameters of the recharge target layer include: porosity, permeability coefficient K, confined water head h0 and thickness M of the recharge target layer; the larger the recharge flow under unit diffusion pressure represents the optimal corresponding recharge well type and process parameters, so as to determine the well type and corresponding process parameters of the recharge well;

[0042] S3, construction of recharge well, acquisition of long-term stable recharge flow Q L : carry out variable flow field water injection test, continuously observe the injection pump pressure during injection operation, and determine the suitable long-term stable recharge flow Q according to the change of injection pump pressureL .

[0043] The long-term stable recharge flow rate Q L and the relationship with the rated pump pressure P s of the recharge pump:

[0044]

[0045] In the formula, λ is the friction coefficient, L p is the length of the recharge well, m; g is the acceleration of gravity, H is the burial depth of the recharge target layer; h0 is the confined water head of the recharge target layer; γ is the unit weight of water; K is the permeability coefficient of the recharge target layer; M is the thickness of the recharge target layer; R is the influence radius of the recharge target layer; and r is the inner diameter of the recharge well in the recharge target layer, mm.

[0046] In the embodiments of the present disclosure, the well type includes a straight well, a horizontal well, and a cluster branch well; specifically, the process parameters of the straight well include a well diameter and a well length; specifically, the process parameters of the horizontal well include a well diameter and the length of a horizontal section; and specifically, the process parameters of the cluster branch well include the number of cluster branch wells, the length of the cluster branch wells, and the angle of the cluster branch wells.

[0047] A more detailed scheme of the coal mine water deep well recharge process parameter acquisition method includes:

[0048] Step one, first investigate the regional recharge stratum parameters, including drilling and comprehensive logging, interpreting the distribution of aquifer and aquifuge of the recharge well stratum, and the stratum lithology, burial depth, thickness, and porosity;

[0049] Step two, carry out unsteady flow pumping test to determine the burial depth, porosity, permeability coefficient K d , confined water head, thickness m, and influence radius of the single-layer sandstone aquifer; determine the recharge target layer according to the size of the single-layer sandstone aquifer transmissibility coefficient T; the sandstone aquifer with the largest transmissibility coefficient is the recharge target layer; wherein:

[0050] T=K d m;

[0051] In the formula, K d is the permeability coefficient of the single-layer stratum, and m is the thickness of the single-layer aquifer

[0052] Step three: based on the geological parameters of the recharge target layer, use numerical simulation means to carry out the variation law of the recharge flow rate Q and the diffusion pressure p under the action of different well types, lengths, and different water injection pressures; the geological parameters of the recharge target layer include the porosity, permeability coefficient K, confined water head h0, and aquifer thickness M of the recharge target layer; the larger the recharge flow rate under the unit diffusion pressure represents that the corresponding recharge well type and process parameters are optimal, so as to determine the recharge well type and the corresponding process parameters;

[0053] Step four: according to the recharging well type and corresponding process parameters determined in step three, the construction of the recharging well is carried out;

[0054] Step five: a variable flow field injection test is carried out, the recharging pump pressure during the recharging operation is continuously observed, and the suitable long-term stable recharging flow Q is determined according to the change of the recharging pump pressure L ;

[0055] The relationship between the long-term stable recharging flow Q L and the rated pump pressure P s of the recharging pump is:

[0056]

[0057] In the formula: λ is the friction coefficient, L p is the length of the recharging well, m; g is the acceleration of gravity, H is the burial depth of the recharging target layer; h0 is the confined water head of the recharging target layer; γ is the unit weight of water; K is the permeability coefficient of the recharging target layer; M is the thickness of the recharging target layer; R is the influence radius of the recharging target layer; and r is the inner diameter of the recharging well in the recharging target layer, mm.

[0058] The present application will be further described in detail in combination with the following examples.

[0059] Example one:

[0060] The coal mine water deep well recharging process parameter acquisition method of the present application comprises:

[0061] Step one: first, investigate the regional recharging stratum parameters, including drilling and comprehensive logging, interpreting the distribution of the aquifer and the aquifuge of the recharging well stratum, and the stratum lithology, burial depth, thickness and porosity;

[0062] Investigate the regional recharging stratum parameters, determine the thick 100m fine sandstone aquifer of the upper Permian Shiqianfeng group (P3sh) which can be used for the mine water deep well recharging, the burial depth is 2200m, the porosity is 0.15; the thick 300m medium sandstone aquifer of the lower Triassic Liujiaogou group (T1l), the burial depth is 1900m, the porosity is 0.21; and the thick 200m medium fine sandstone aquifer of the Heshanggou group (T1h), the burial depth is 170m, the porosity is 0.17.

[0063] Step two: carry out a non-steady flow pumping test to determine the burial depth, porosity, permeability coefficient K d , confined water head, single aquifer thickness m and influence radius of the single sandstone aquifer; according to the size of the single sandstone aquifer transmissibility T, determine the recharging target layer, the sandstone aquifer with the largest transmissibility is the recharging target layer; wherein:

[0064] T=Kd m;

[0065] Where: K d denoted as the permeability coefficient of a single rock layer, and m is the thickness of a single aquifer.

[0066] The permeability coefficient K of a 100m thick fine sandstone aquifer in the Upper Permian Shiqianfeng Formation (P3sh) was determined through experiments. d It is 0.011 (m·d) -1 The confined aquifer head is 200m, the single aquifer thickness is 100m, the radius of influence is 100m, and the hydraulic conductivity is 1.1m. 2 ·d -1 );

[0067] The permeability coefficient K of the 200m thick medium sandstone aquifer in the Lower Triassic Liujiagou Formation (T1l) d It is 0.015 (m·d) -1 ),

[0068] The confined head is 400m, the thickness of a single aquifer is 200m, the radius of influence is 200m, and the hydraulic conductivity is 3.0 (m). 2 ·d -1 );

[0069] The permeability coefficient K of the 200m thick medium-fine sandstone aquifer in the Heshangou Formation (T1h) d It is 0.012 (m·d) -1 The confined aquifer head is 300m, the single-layer aquifer thickness is 200m, the radius of influence is 150m, and the hydraulic conductivity is 2.4 (m). 2 ·d -1 );

[0070] Therefore, the 200m thick medium sandstone aquifer of the Triassic Liujiagou Formation (T1l) was selected as the target layer for recharge.

[0071] Step 3: Based on the geological parameters of the target reinjection layer, numerical simulation is used to investigate the variation of reinjection flow rate Q and diffusion pressure p under different well types, lengths, and injection pressures. The geological parameters of the target reinjection layer include: porosity, permeability coefficient K, confined water head h0, and aquifer thickness M. A higher reinjection flow rate per unit diffusion pressure indicates that the corresponding reinjection well type and process parameters are optimal, thus determining the reinjection well type and corresponding process parameters. Well types include vertical wells, horizontal wells, and cluster branch wells. The process parameters of vertical wells include well diameter and well length; the process parameters of horizontal wells include well diameter and the length of the horizontal section; the process parameters of cluster branch wells include the number of cluster branch wells, the length of the cluster branch wells, and the angle of the cluster branch wells.

[0072] The Liujiagou group (T1l) sandstone aquifer porosity 0.21, thickness 200m, permeability coefficient 0.015 (m·d -1 ), buried depth 1900m, confined water head 400m, the basic parameters, using numerical simulation studies, as Figs. 1-2 shown, also in the case of water injection pressure of 8MPa, well diameter 200mm conditions under the length of the well 200m working conditions of the recharge flow is 100m 3 / h, hole bottom diffusion pressure is 10MPa, unit diffusion pressure under the recharge flow is 10m 3 / (h·MPa)

[0073] Well diameter of 200mm conditions under the length of the horizontal well 200m working conditions of the recharge flow is 120m 3 / h, hole bottom diffusion pressure is 20MPa, unit diffusion pressure under the recharge flow is 6m 3 / (h·MPa);

[0074] Well diameter of 200mm conditions under the length of the horizontal well 200m working conditions of the recharge flow is 120m 3 / h, hole bottom diffusion pressure is 20MPa, unit diffusion pressure under the recharge flow is 6m 3 / (h·MPa);

[0075] Therefore, the preferred well type is cluster branch well, well diameter is 200mm, the number of branch wells is 2, the length of branch well is 565m, and the vertical angle of branch well is 45 degrees.

[0076] Step four: determine the ground mine water pretreatment system, in order to prevent clogging of the mine water pretreatment, the filtration accuracy should be determined according to the particle diameter and the content of the coal mine water particles and suspended solids of each level;

[0077] Step five: according to the type of recharge well determined in step three and the corresponding process parameters, the recharge well is constructed;

[0078] According to the cluster branch well type, the corresponding process parameters are well diameter of 200mm, the number of branch wells is 2, the length of branch well is 565m, and the vertical angle of branch well is 45 degrees.

[0079] Step six: carry out variable flow field water injection test, continuously observe the injection pump pressure during the injection operation, and determine the suitable long-term recharge flow Q L according to the change of injection pump pressure;

[0080] The relationship between the long-term stable recharge flow Q L and the rated pump pressure P s of the injection pump is:

[0081]

[0082] wherein λ is the friction coefficient, L p is the length of the recharging well, m; g is the acceleration of gravity, H is the burial depth of the recharging target layer; h0 is the confined water head of the recharging target layer; γ is the unit weight of water; K is the permeability coefficient of the recharging target layer; M is the thickness of the recharging target layer; R is the influence radius of the recharging target layer; and r is the inner diameter of the recharging well in the recharging target layer, mm.

[0083] The rated pump pressure P S of the selected pump is 10 MPa, λ is the friction coefficient, and the value is 0.005, L p is the working tube length, and is 2100 m; g is the acceleration of gravity, and is 9.8 N / m 2 ; H is the burial depth of the recharging target layer, and the value is 1900 m; h0 is the confined water head of the recharging target layer, and the value is 400 m; γ is the unit weight of water, and the value is 9800 KN / m 2 ; K is the permeability coefficient of the recharging target layer, and is 0.015 (m·d -1 ); M is the thickness of the recharging target layer, and is 200 m; R is the influence radius of the recharging target layer, and is 200 m; and r is the inner diameter of the recharging well in the recharging target layer, and is 0.2 m. L 3

[0084] Step seven: according to the determined long-term recharging flow rate Q L = 125 m 3 / h, the water injection pump is adjusted for long-term high-flow recharging, and the pressure gauge during the recharging operation is continuously observed. If the pressure increases sharply, the recharging operation can be performed to prevent clogging.

[0085] The preferred embodiments of the present disclosure are described in detail above in combination with the drawings, but the present disclosure is not limited to the specific details in the above-described embodiments. Within the technical concept range of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection range of the present disclosure.

[0086] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combination manners are not described again in the present disclosure.

[0087] In addition, various different embodiments of the present disclosure can also be combined in any manner, as long as they do not deviate from the idea of the present disclosure, and they should also be considered as disclosed content of the present disclosure.​​

Claims

1. A method for obtaining process parameters of deep well reinjection of coal mine water, characterized in that, include: S1. Determine the target layer for reinjection: Determine the permeability coefficient K of a single sandstone aquifer. d And thickness m; the target layer for recharge is determined based on the magnitude of the hydraulic conductivity T of a single sandstone aquifer, and the sandstone aquifer with the highest hydraulic conductivity is the target layer for recharge; where: ； S2. Determine the well type and corresponding process parameters of the reinjection well: Based on the geological parameters of the target reinjection layer, use numerical simulation to study the reinjection flow rate Q and diffusion pressure under different well types, lengths, and injection pressures. p The variation pattern of the target layer for reinjection includes the following geological parameters: porosity, permeability coefficient, confined head, and thickness of the target layer. The larger the reinjection flow rate per unit diffusion pressure, the more optimal the corresponding reinjection well type and process parameters are, thereby determining the reinjection well type and corresponding process parameters. S3. Construct a reinjection well to obtain a long-term stable reinjection flow rate Q. L Conduct variable flow rate field water injection tests, continuously monitor the reinjection pump pressure during reinjection operations, and determine the appropriate long-term stable reinjection flow rate Q based on the changes in reinjection pump pressure. L ; The method for obtaining long-term stable reinjection flow rate Q L With the rated pump pressure of the reinjection pump Relationship: ； In the formula: λ is the friction coefficient, L p denoted as , where is the length of the recharge well (m); g is the gravitational acceleration; H is the burial depth of the recharge target layer; h0 is the confined water head of the recharge target layer; γ is the unit weight of water; K is the permeability coefficient of the recharge target layer; M is the thickness of the recharge target layer; R is the radius of influence of the recharge target layer; and r is the inner diameter of the recharge well within the recharge target layer (mm).

2. The method for obtaining process parameters of deep well recharge in coal mines according to claim 1, characterized in that, The well types mentioned include vertical wells, horizontal wells, and cluster branch wells.

3. The method for obtaining process parameters of deep well recharge in coal mines according to claim 2, characterized in that, The process parameters of the vertical well include well diameter and well length; The process parameters of the horizontal well include the well diameter and the length of the horizontal section; The process parameters of the cluster branch wells include the number of cluster branch wells, the length of the cluster branch wells, and the angle of the cluster branch wells.

4. A method for obtaining process parameters of deep well reinjection of coal mine water, characterized in that, include: Step 1: First, investigate the parameters of the reinjection formation in the area, including drilling and comprehensive logging, interpreting the distribution of aquifers and impermeable layers in the reinjection well formation, as well as the formation lithology, burial depth, thickness and porosity; Step 2: Conduct unsteady flow pumping tests to determine the permeability coefficient, confined head, thickness (m), and radius of influence of a single sandstone aquifer. Based on the hydraulic conductivity (T) of the single sandstone aquifer, determine the target layer for recharge; the sandstone aquifer with the highest hydraulic conductivity is the target layer for recharge. Where: ； Where: K d denoted as the permeability coefficient of a single sandstone aquifer, and m is the thickness of the single aquifer. Step 3: Based on the geological parameters of the target reinjection layer, numerical simulation methods are used to study the reinjection flow rate Q and diffusion pressure under different well types, lengths, and injection pressures. p The variation pattern of the target layer for reinjection includes the following geological parameters: porosity, permeability coefficient, confined head, and aquifer thickness M. The larger the reinjection flow rate per unit diffusion pressure, the more optimal the corresponding reinjection well type and process parameters are, thereby determining the reinjection well type and corresponding process parameters. Step 4: Construct the reinjection wells according to the well type and corresponding process parameters determined in Step 3; Step 5: Conduct a variable flow rate on-site water injection test, continuously monitor the reinjection pump pressure during the reinjection operation, and determine the long-term stable reinjection flow rate Q based on the changes in the reinjection pump pressure. L ; The method for obtaining long-term stable reinjection flow rate Q L With the rated pump pressure of the reinjection pump Relationship: ； In the formula: λ is the friction coefficient, L p denoted as , where is the length of the recharge well (m); g is the gravitational acceleration; H is the burial depth of the recharge target layer; h0 is the confined water head of the recharge target layer; γ is the unit weight of water; K is the permeability coefficient of the recharge target layer; M is the thickness of the recharge target layer; R is the radius of influence of the recharge target layer; and r is the inner diameter of the recharge well within the recharge target layer (mm).

5. The method for obtaining process parameters of deep well recharge of coal mine water according to claim 4, characterized in that, The well types mentioned include vertical wells, horizontal wells, and cluster branch wells.

6. The method for obtaining process parameters of deep well recharge of coal mine water according to claim 5, characterized in that, The process parameters of the vertical well include well diameter and well length; The process parameters of the horizontal well include the well diameter and the length of the horizontal section; The process parameters of the cluster branch wells include the number of cluster branch wells, the length of the cluster branch wells, and the angle of the cluster branch wells.

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