Drill hole hydrophobic coefficient calculation method based on underground group hole drainage test

Abstract

The invention relates to the technical field of hydrogeological survey, in particular to a borehole hydrophobic coefficient calculation method based on an underground group hole drainage test. The method comprises the following steps: respectively carrying out group hole drainage tests of water drainage and water pressure monitoring of a target confined aquifer by utilizing drainage holes and monitoring holes; establishing an equation set corresponding to each frequency based on an unstable flow Jacob formula according to the collected group hole water discharge test data, and solving to obtain a water guide coefficient and an elastic water release coefficient; and solving the borehole hydrophobic coefficient by using the water conductivity coefficient and the elastic water release coefficient. In order to ensure that the calculation result has correctability, the number of the drainage drill holes is not less than 3, the number of the monitoring holes is not less than 2, the properties of the drainage holes and the monitoring holes can be mutually converted, the stable drainage flow of the drill holes is not less than 2 frequencies, and the test of the frequency is stopped after the water pressure of the monitoring holes is stable. According to the method, the complexity of hydrogeological conditions of the aquifer and inter-hole interference during multi-hole drainage are considered, so that a calculation result is more reliable and accords with reality.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogeological exploration, and in particular to a method for calculating a borehole hydrophobicity coefficient based on an underground group hole water discharge test. Background Art

[0002] Coal is an important basic energy source and plays an important role in the national economy. However, the safety of coal mining has always been the focus of attention, especially in the process of coal mining, where water disasters of varying degrees often occur. With the continuous increase in mining depth, the threat of water disasters faced by coal mining is also increasing.

[0003] Drainage and pressure reduction is one of the important methods to reduce the threat of water damage to the limestone aquifer at the bottom of the coal seam. Among them, the borehole drainage coefficient is the ratio of the depth drop to the flow rate when the borehole is drained, and its reciprocal is the drainage volume per unit depth drop of the borehole. This coefficient is an important indicator for judging the recharge performance of the aquifer, and it is also an important basis for mines to formulate underground water prevention and control plans. The traditional method for calculating the drainage coefficient is to use the stable water level drop and stable flow rate of the single-hole constant flow discharge test for calculation. Since the depth drop and flow rate of the single-hole discharge test often cannot truly reflect the water richness and recharge conditions of the aquifer, it is more reliable to use the depth drop and flow rate of the group hole discharge test for calculation. Under the condition of group hole discharge, the water level drop of a certain borehole is the result of the comprehensive effect of the group hole discharge. It is difficult to obtain the stable water level drop under its own flow discharge, which makes the calculated borehole drainage coefficient unrealistic. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a method for calculating the borehole hydrophobicity coefficient based on an underground group hole water discharge test. The technical solution adopted is as follows:

[0005] In combination with an embodiment of the present invention, a method for calculating the hydrophobicity coefficient of a borehole based on a downhole group hole water discharge test is provided, the method comprising:

[0006] Using the completed drainage holes and monitoring holes in the well, group-hole drainage tests were carried out for water drainage and water pressure monitoring of the target confined aquifer, and the water pressure and flow data at each time point during the drainage process were recorded;

[0007] The group hole water discharge test includes at least two frequency tests; based on the Jacob formula of unsteady flow, the equation groups corresponding to each frequency are established using the data collected at each frequency of the group hole water discharge test;

[0008] The equations corresponding to each frequency are solved respectively to obtain the water conductivity and elastic water release coefficient of the detection area; the borehole hydrophobicity coefficient corresponding to each frequency is obtained according to the water conductivity and elastic water release coefficient of the detection area; the borehole hydrophobicity coefficient of the detection area is obtained according to the borehole hydrophobicity coefficient corresponding to each frequency.

[0009] Preferably, the drain hole and the monitoring hole include:

[0010] The number of drainage holes in the group-hole drainage test is set to a first preset number, and the number of monitoring holes is set to a second preset number; wherein, the number of drainage holes shall not be less than 3, the number of monitoring holes shall not be less than 2, and the functions of the drainage holes and the monitoring holes can be converted to each other.

[0011] Preferably, the group hole water discharge test includes at least two frequency tests, including:

[0012] The number and position of drainage holes and monitoring holes used in each frequency test in the group-hole drainage experiment are different.

[0013] Preferably, the water pressure and flow rate data at each time point during the water discharge process are recorded, including:

[0014] In each frequency of water release test, the uneven collection method is used to collect data. In the first period, the data collection interval is the first interval; in the second period, the data collection interval is the second interval; in the third period, the data collection interval is the third interval; after the third period, the data collection interval is the fourth interval until the data collection is completed.

[0015] Preferably, the set of equations corresponding to each frequency is:

[0016]

[0017] Among them, s1, s2, …, s m is the total water level drop of each monitoring hole corresponding to a frequency; Q i is the flow rate of the ith drain hole; t1, t2, …, t m The time it takes for the water pressure of each monitoring hole corresponding to a frequency to reach stability; r i1 , r i2 ,…,r im is the distance between the ith drainage hole and each monitoring hole in a frequency; T is the water conductivity; μ * is the elastic water release coefficient.

[0018] Preferably, the equation groups corresponding to each frequency are solved respectively to obtain the water conductivity and elastic water release coefficient of the detection area, including:

[0019] The equation group corresponding to each frequency is solved to obtain the water conductivity and elastic water release coefficient corresponding to each frequency; the water conductivity corresponding to each frequency is averaged to obtain the water conductivity of the detection area; the elastic water release coefficient corresponding to each frequency is averaged to obtain the elastic water release coefficient of the detection area.

[0020] Preferably, the borehole hydrophobicity coefficient corresponding to each frequency is obtained according to the water conductivity and elastic water release coefficient of the detection area, including:

[0021] Construct the relationship between the borehole hydrophobicity coefficient and the following formula:

[0022]

[0023] in, represents the borehole hydrophobicity coefficient corresponding to the jth monitoring hole in the ath frequency; T c and μ * c represent the water conductivity and elastic water release coefficient of the detection area respectively; represents the time it takes for the water pressure of the jth monitoring hole in the ath frequency to reach stability; r w Indicates the drilling radius;

[0024] The drilling hydrophobicity coefficient corresponding to each frequency is obtained according to the drilling hydrophobicity coefficient relationship.

[0025] Preferably, the borehole hydrophobicity coefficient of the detection area is obtained according to the borehole hydrophobicity coefficient corresponding to each frequency, including:

[0026] The borehole hydrophobicity coefficients corresponding to each frequency are averaged to obtain the borehole hydrophobicity coefficient of the detection area.

[0027] The embodiments of the present invention have at least the following beneficial effects: the present invention arranges drainage holes and monitoring holes in the detection area according to the hydrogeological conditions, and drills holes according to the positions of the drainage holes and monitoring holes. By using the method of simultaneous drainage of multiple holes, the hydrogeological conditions of the well field can be fully revealed, and a large-scale, large-depth drawdown excitation flow field can be formed, which will provide a reliable basis for the calculation of hydrogeological parameters, and can truly reflect the water-richness and recharge conditions of the aquifer, thereby obtaining more comprehensive and accurate test data;

[0028] At the same time, water from the confined aquifer is released according to the completed drainage holes, water pressure is monitored at the monitoring holes, and the equation group corresponding to each frequency is calculated based on the Jacob formula of unsteady flow using the data collected at each frequency. The equation group corresponding to each frequency can accurately simulate the flow of water in the rock formation, taking into account the mutual influence between multiple pores and factors such as the formation structure, thereby improving the reliability and accuracy of the calculation results;

[0029] Finally, the equation group corresponding to each frequency is solved to obtain the water conductivity and elastic water release coefficient of the detection area, and then the borehole hydrophobicity coefficient corresponding to the equation group corresponding to each frequency is obtained, and then the borehole hydrophobicity coefficient of the detection area is obtained. Through systematic analysis and processing of the test data, the borehole hydrophobicity coefficient of the detection area can be calculated quickly and accurately. This method not only considers the characteristics of a single borehole, but also comprehensively considers the interaction between multiple holes, so that the calculation results are more in line with the actual situation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A method flow chart of a method for calculating a borehole hydrophobicity coefficient based on a downhole group hole water discharge test provided by an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a downhole drilling structure of a method for calculating a borehole hydrophobicity coefficient based on a downhole group hole water discharge test provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of a water level drop curve of a method for calculating a borehole hydrophobicity coefficient based on an underground group hole water discharge test provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the method for calculating the borehole hydrophobicity coefficient based on the downhole group hole water discharge test proposed by the present invention, its specific implementation method, structure, characteristics and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0035] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0036] The following is a detailed description of a method for calculating the borehole hydrophobicity coefficient based on an underground group hole water discharge test provided by the present invention in conjunction with the accompanying drawings.

[0037] Example:

[0038] The main application scenarios of the present invention are:

[0039] The present invention uses an underground group-hole water discharge test system to monitor the dynamic changes of water discharge volume and water level drop, analyze the shape, size and expansion process of the drop funnel, and combine with the unsteady flow theory to study the hydraulic connection between each aquifer in the groundwater system, thereby obtaining hydrogeological parameters such as permeability coefficient. Subsequently, the borehole hydrophobicity coefficient is calculated according to the unsteady flow Jacob formula to evaluate the hydrophobicity of the coal seam floor pressure aquifer. The present invention provides a method for eliminating the influence of other drainage holes under the conditions of the group-hole water discharge test, establishing a calculation formula for the ratio of single-hole water level drop and water discharge flow, and then obtaining the borehole hydrophobicity coefficient.

[0040] See also Figure 1 , which shows a flow chart of a method for calculating the borehole hydrophobicity coefficient based on a downhole group hole water discharge test provided by an embodiment of the present invention, the method comprising the following steps:

[0041] Step S1, using the completed drainage holes and monitoring holes in the well, respectively carry out group hole drainage tests for water drainage and water pressure monitoring of the target confined aquifer, and record the water pressure and flow data at each time point during the drainage process.

[0042] Water damage is the most common accident in coal mining. Therefore, in the process of coal mining, it is necessary to explore the hydrogeological parameters to provide a scientific basis for the prevention and control of water damage. First of all, it is necessary to comprehensively detect the hydrogeological conditions in the early stage of the area and reasonably arrange the drainage holes and monitoring holes. It should be noted that the location of the drainage holes and monitoring holes needs to be arranged by the implementers according to the actual hydrogeological conditions in the detection area.

[0043] Preferably, in the embodiment of the present invention, a first preset number of drainage holes is designed based on the hydrogeological conditions of the detection area, and the first preset number is 7, which are respectively recorded as A, B, C, D, E, F, and G; at the same time, a second preset number of monitoring holes is designed, and the second preset number is 3, which are respectively recorded as H, I, and J. The implementer can adjust the values ​​of the first preset number and the second preset number according to the actual situation of the detection area, that is, the total number of drainage holes and monitoring holes in the group hole drainage test is the first preset number and the second preset number, respectively.

[0044] At the same time, the distance between the drain holes should ensure that when one hole releases water, the other hole will produce a certain water level reduction (greater than 20cm); the drain holes should be selected at locations with large water output or relatively low elevation as much as possible. The number of drain holes shall not be less than 3, and the number of monitoring holes shall not be less than 2, and the functions of the drain holes and monitoring holes can be converted to each other.

[0045] After determining the specific locations of the drainage holes and monitoring holes, drilling is carried out. The downhole drilling structure is as follows: Figure 2 As shown, Figure 2 1 indicates the outer plugging of the pipe, 2 indicates the first-level casing, 3 indicates the water-stopping filler, 4 indicates the second-level casing, 5 indicates the filter pipe, 6 indicates the thickness of the water-blocking layer, and 7 indicates the thickness of the aquifer. Drill the drain holes and monitoring holes according to the drilling process. The drilling process is the drilling construction sequence, which is as follows:

[0046] First, a φ133mm drill bit was used to drill, and 10m of the first-stage φ127mm casing and water-stop filler were lowered, and the casing was grout-injected to consolidate it;

[0047] Next, after the casing solidifies, drill through the hole to the bottom of the hole, install the hole device and pressure gauge, and do a pressure test. The orifice pressure is ≥3.6MPa, and the pressure stabilization time must exceed 30min. After the test is qualified, the orifice water control valve and blowout prevention device are installed before drilling can continue;

[0048] Furthermore, a φ113mm drill bit was used to drill and lower the second-stage φ108mm casing for 20m, and the casing was grout-injected for consolidation;

[0049] Then, after the casing solidifies, drill through the hole to the bottom of the hole, install the hole device and pressure gauge, and do a pressure test. The orifice pressure must be ≥7.2MPa, and the pressure stabilization time must exceed 30min. After the test is qualified, the orifice water control valve and blowout prevention device must be installed before drilling can continue;

[0050] Finally, the diameter is changed to Φ94mm and the crushing is drilled to the designed hole depth, and then the water filter pipe is installed. Among them, the consolidation casing is quickly consolidated using cement-water glass double liquid slurry or inorganic quick-setting materials.

[0051] At the same time, it is also necessary to design the orifice device to facilitate the water discharge test. The orifice device consists of a valve, a pressure gauge, a flow meter, a pressure measuring tube and a water discharge pipe. The self-flowing water of the pressurized aquifer flows out through the borehole downhole, and the water pressure is measured by the pressure measuring tube and the pressure gauge, and the flow rate is measured by the flow meter, and finally discharged through the water discharge pipe. The orifice device is mainly used to monitor and adjust the flow rate and pressure during the water discharge test, and it is also necessary to ensure that the specifications and installation depths of the filters of each water discharge hole should be as similar as possible.

[0052] After the drainage holes and monitoring holes are completed, it is necessary to drain the water volume of the confined aquifer according to the completed drainage holes, and monitor the water pressure of the monitoring holes, that is, to conduct a group hole drainage test, and conduct a non-stable flow drainage of a fixed flow rate in the confined aquifer of the coal seam floor. The total amount of water discharged should be less than the drainage capacity of the mine. The drainage sequence is to first discharge water at a small flow rate, and then gradually increase the drainage holes to increase the water discharge volume, and at least two frequencies of drainage tests should be conducted. At the same time, it is necessary to monitor the water volume, water pressure and temperature synchronously, and the monitoring frequency should be from frequent to sparse.

[0053] Preferably, the present invention takes two frequency water discharge tests as an example, which are respectively recorded as the first frequency and the second frequency. In the first frequency, the A-F water discharge holes are opened, and in the second frequency, the A-G water discharge holes are opened. The water discharge holes and monitoring holes selected for the first frequency and the second frequency are shown in Table 1. The number and position of the water discharge holes and monitoring holes used in each frequency test in the group hole water discharge experiment are not completely the same:

[0054] Table 1 Drilling and monitoring hole layout

[0055] Frequency of water discharge Drain hole / flow monitoring hole Water pressure monitoring hole First frequency A, B, C, D, E, F H.I Second frequency A, B, C, D, E, F, G H.J.

[0056] Among them, the monitoring holes used in the first frequency are H and I monitoring holes, and the monitoring holes used in the second frequency are H and J monitoring holes; the discharge holes are used to monitor the flow data, and the monitoring holes are used to monitor the pressure data; the distances between each discharge hole and the monitoring hole are shown in Table 2:

[0057] Table 2 Distance between drain hole and monitoring hole (m)

[0058] drilling A B C D E F G H 150 150 153 157 160 161 163 I 155 153 150 152 155 150 158 J 161 160 157 155 153 150 160

[0059] Before conducting the water discharge test, the large pump, drainage pipeline, and power supply system need to be inspected and repaired. There must be no less than two spare drainage pumps to ensure that one water tank is supplied with water and the other is on standby.

[0060] In each frequency, the flow rate of the discharge hole and the water pressure (water level) of the monitoring hole should be observed synchronously, and the data collection method should be used for uneven collection. Specifically, in the first period, the data collection interval is the first interval; in the second period, the data collection interval is the second interval; in the third period, the data collection interval is the third interval; after the third period, the data collection interval is the fourth interval until the data collection is completed; preferably, in the embodiment of the present invention, the first period, the second period, and the third period correspond to the 1st to 10th minute, the 10th to 20th minute, and the 20th to 120th minute after the start of the water discharge test, respectively. Correspondingly, the first interval, the second interval, the third interval, and the fourth interval are measured once every 1 minute, once every 2 minutes, once every 10 minutes, and once every 30 minutes, respectively; the implementer can make adaptive adjustments to the first period, the second period, the third period, and the first interval, the second interval, the third interval, and the fourth interval according to the actual situation of the detection area and the drilling, so as to better fit the actual situation of the detection area.

[0061] At the same time, during the water discharge test, each water discharge hole is required to maintain a constant flow rate, and the water discharge flow rate is kept constant from beginning to end, and its change range is not greater than 3%. In the process of data collection, the accuracy of underground water pressure observation is required to reach 1 / 2 of the minimum scale of the pressure gauge, and the water volume observation accuracy of the flow meter is required to reach 0.1m 3The data collected are shown in Table 3 and Table 4. The water level drop curve of monitoring hole H is shown in Figure 3 shown.

[0062] Table 3 Monitoring of water discharge hole flow (m 3 / h)

[0063] stage A B C D E F G total First frequency 50 53 50 52 65 80 0 350 Second frequency 50 53 50 62 65 80 90 450

[0064] Table 4 Water pressure monitoring situation of water pressure monitoring holes

[0065]

[0066] Thus, the data collected in the water discharge test at each frequency were obtained.

[0067] Step S2, the group hole water release test includes at least two frequency tests; based on the Jacob formula of unsteady flow, the data collected at each frequency of the group hole water release test are used to establish the equation group corresponding to each frequency.

[0068] For the single-hole water discharge test, the analysis process usually requires the establishment of an unsteady flow mathematical model of the confined aquifer to solve the basic hydrogeological parameters of the study area. According to the unsteady flow Jacob formula, the water level drop caused by the discharge hole to any point (monitoring hole) in the single-hole water discharge test is:

[0069]

[0070] Where s represents the water level drop at the monitoring hole, in m; Q represents the flow rate at the discharge hole, in m 3 / h; π is pi, dimensionless; T is the water conductivity, unit is m 2 / h; t represents the time it takes for the water pressure in the monitoring hole to reach stability, in h; μ * represents the elastic water release coefficient, dimensionless; r represents the distance from the drainage hole to the monitoring hole, in meters.

[0071] For the present invention, in the group hole water discharge test, the water level drop produced by each monitoring hole is the result of the combined effect of each water discharge hole. According to the superposition principle, the total depth drop produced by the group hole water discharge at any monitoring hole is:

[0072]

[0073] Among them, s j represents the total water level drop of the jth monitoring hole in the group hole water release test, j = 1, 2, 3, ..., m, m is the total number of monitoring holes; s ij represents the water level drop caused by the i-th drainage hole to the j-th monitoring hole, i = 1, 2, 3, ..., n represents the total number of drainage holes; Q irepresents the flow rate of the ith drain hole; T represents the water conductivity; t j represents the time it takes for the water pressure at the jth monitoring hole to reach stability, r ij is the distance from the i-th drainage hole to the j-th monitoring hole; μ * is the elastic water release coefficient.

[0074] Furthermore, the water level drop caused by each monitoring hole is the result of the combined effect of each discharge hole. In a water discharge experiment of a certain frequency, the following equation group model can be established for n discharge holes and m monitoring holes:

[0075]

[0076] Among them, s1, s2, …, s m is the total water level drop of each monitoring hole corresponding to a frequency, m; Q i is the flow rate of the ith drain hole, m 3 / h; t1, t2, …, t m The time it takes for the water pressure of each monitoring hole corresponding to a frequency to reach stability, h; r i1 , r i2 ,…,r im is the distance between the ith drainage hole and each monitoring hole in a frequency, m; T is the water conductivity; μ * is the elastic water release coefficient, dimensionless. From this, we can get the equation group corresponding to each frequency.

[0077] Taking the first frequency and the second frequency as examples, based on the data collected at the first frequency and the second frequency, the first equation group and the second equation group corresponding to the first frequency are respectively constructed based on the equation group model. The first equation group is:

[0078]

[0079] Among them, s 1H and 1I They represent the total water level drop of monitoring hole H and monitoring hole I in the first frequency respectively; Q i1 represents the flow rate of the ith drain hole in the first frequency; T1 represents the water conductivity in the first frequency; t 1H and t 1I They respectively represent the time taken for the water pressure of monitoring hole H and monitoring hole I to reach stability in the first frequency; μ * 1 means the elastic water release coefficient in the first frequency; r iH and r iI They represent the distance from the ith drain hole to the monitoring hole H and the distance to the monitoring hole I. In the first frequency, since the drain holes A to F are opened, only the drain holes A to F have an effect on the monitoring holes H and I, so the value of n is 6.

[0080] The second set of equations is:

[0081]

[0082] Among them, s 2H and 2I They represent the total water level drop of monitoring hole H and monitoring hole J in the second frequency respectively; Q i2 represents the flow rate of the ith drain hole in the second frequency; T2 represents the water conductivity in the second frequency; t 2H and t 2J They represent the time taken for the water pressure at monitoring hole H and monitoring hole J to reach stability in the second frequency; μ * 2 represents the elastic water release coefficient in the second frequency; r iH and r iJ They represent the distance from the i-th drain hole to the monitoring hole H and the distance to the monitoring hole J respectively.

[0083] In the second frequency, since the drain holes opened are A~G, the drain holes A~G act on the monitoring holes H and J, so the value of n is 7.

[0084] Therefore, according to the first frequency and the second frequency water release test, the first and second equation groups corresponding to the first and second frequencies are constructed respectively, and further analysis is performed based on the first and second equation groups to solve more detailed hydrogeological parameters in the detection area. Analyzing the equation groups corresponding to each pair of frequencies can obtain more detailed hydrogeological parameters in the detection area.

[0085] Step S3, respectively solve the equation group corresponding to each frequency to obtain the water conductivity and elastic water release coefficient of the detection area; obtain the borehole hydrophobicity coefficient corresponding to each frequency according to the water conductivity and elastic water release coefficient of the detection area; obtain the borehole hydrophobicity coefficient of the detection area according to the borehole hydrophobicity coefficient corresponding to each frequency.

[0086] Furthermore, the fsolve function in Matlab is used to solve the equation group corresponding to each frequency to obtain the water conductivity and elastic water release coefficient corresponding to each frequency. The water conductivity corresponding to each frequency is averaged to obtain the water conductivity of the detection area; the elastic water release coefficient corresponding to each frequency is averaged to obtain the elastic water release coefficient of the detection area.

[0087] For the first and second equations, the fsolve function in Matlab is used to solve them respectively, and then further analysis is performed based on the solved values ​​to obtain the water conductivity and elastic water release coefficient of the detection area. Specifically, the first equation group is solved to obtain the water conductivity and elastic water release coefficient corresponding to the first equation group; the second equation group is solved to obtain the water conductivity and elastic water release coefficient corresponding to the second equation group; the water conductivity corresponding to the first and second equations is averaged to obtain the water conductivity of the detection area; the elastic water release coefficients corresponding to the first and second equations are averaged to obtain the elastic water release coefficient of the detection area.

[0088] In the embodiment of the present invention, the water conductivity corresponding to the first set of equations (first frequency) is 61.505m 2 / d, the elastic water release coefficient is 0.000402; the water conductivity corresponding to the second equation group (second frequency) is 47.677m 2 / d, the elastic water release coefficient is 0.000121. Taking the average value, the water conductivity of the detection area is 54.591m 2 / d, the elastic water release coefficient is 0.000262.

[0089] After obtaining the water conductivity and elastic water release coefficient of the detection area, further analysis is required to obtain the borehole hydrophobicity coefficient corresponding to each frequency. Specifically, for the monitoring hole, the distance between the drainage hole and the monitoring hole should be changed to the borehole radius, that is, r = r w For the borehole hydrophobicity coefficient, what is required is the borehole hydrophobicity coefficient of the drainage hole, and r = r w That is, to calculate the flow rate and depth drawdown at the well wall of the drainage hole. In this test, the water pressure changes of the drainage holes were not observed, but because the drainage holes were relatively concentrated and some monitoring holes were close to the drainage holes, the data of the monitoring holes were used to calculate the borehole hydrophobicity coefficient and to construct the depth drawdown relationship model of the monitoring holes. The depth drawdown relationship model is:

[0090]

[0091] Among them, s c Indicates the water level drop of the drain hole. However, since the water level drop of the drain hole is not obtained in the present invention, it is necessary to use the monitoring hole data instead; Q f represents the discharge flow rate of the drain hole, r w Indicates the drilling radius; T c and μ * c represent the water conductivity and elastic water release coefficient respectively; t c Indicates the time it takes for the water pressure in the monitoring hole to stabilize.

[0092] Furthermore, the relationship between the depth reduction s of the drainage hole and the flow rate Q is constructed according to the depth reduction relationship model, which is specifically:

[0093]

[0094] in, represents the borehole hydrophobicity coefficient corresponding to the jth monitoring hole in the ath frequency; T c and μ * c The hydraulic conductivity and elastic water release coefficient of the detection area are respectively expressed; represents the time it takes for the water pressure of the jth monitoring hole in the ath frequency to reach stability; r w It should be noted that the calculation does not require the water level drop and flow rate values. The required monitoring hole data can be entered into the borehole hydrophobicity coefficient, and the borehole hydrophobicity coefficient corresponding to each frequency can be obtained according to the borehole hydrophobicity coefficient relationship. Then the borehole hydrophobicity coefficient corresponding to each frequency is averaged to obtain the borehole hydrophobicity coefficient of the detection area.

[0095] In the embodiment of the present invention, the values ​​of a are 1 and 2, respectively, representing the first frequency and the second frequency; the values ​​of j are 1, 2 and 3, respectively representing the monitoring holes H, I and J. Thus, the borehole hydrophobicity coefficient corresponding to the first frequency can be obtained, which are and represents the borehole hydrophobicity coefficients corresponding to the first frequency monitoring holes H and I; the borehole hydrophobicity coefficients corresponding to the second frequency are respectively and The borehole hydrophobicity coefficients corresponding to the second frequency monitoring holes H and J are shown in Table 5. The borehole hydrophobicity coefficients corresponding to the first frequency and the second frequency obtained in the present invention are respectively:

[0096] Table 5 Summary of drilling hydrophobicity coefficient

[0097]

[0098] It can be seen that the borehole hydrophobicity coefficient obtained in the embodiment of the present invention is between 29.568 and 40.757 min / m 2 The average value of the borehole hydrophobicity coefficients obtained at the first and second frequencies was further calculated as the borehole hydrophobicity coefficient of the detection area, and the average value was 35.199 min / m 2 .

[0099] When the borehole hydrophobicity coefficient is ≥10, it means that the recharge is weak and easy to drain; when 3<the borehole hydrophobicity coefficient<10, it means that the recharge is strong and can be drained; when the borehole hydrophobicity coefficient is ≤3, it means that the recharge is very strong and cannot be drained.

[0100] The borehole hydrophobicity coefficient of the detection area is obtained by calculation, which provides a reference for subsequent drainage. It should be noted that when obtaining the borehole hydrophobicity coefficient, although the purpose is to determine the borehole hydrophobicity coefficient of the drainage hole, in a detection area, the data of the monitoring hole can be used to solve the corresponding borehole hydrophobicity coefficient, thereby obtaining the borehole hydrophobicity coefficient of the detection area, thereby representing the borehole hydrophobicity coefficient of the drainage hole.

[0101] It should be noted that the above-mentioned sequence of the embodiments of the present invention is only for description and does not represent the advantages and disadvantages of the embodiments. The above-mentioned specific embodiments of this specification are described. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0102] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for calculating the borehole hydrophobicity coefficient based on a downhole group hole drainage test, characterized in that: The method includes: Using the completed drainage holes and monitoring holes in the well, group-hole drainage tests were carried out for water drainage and water pressure monitoring of the target confined aquifer, and the water pressure and flow data at each time point during the drainage process were recorded; The group hole water discharge test includes at least two frequency tests; based on the Jacob formula of unsteady flow, the equation groups corresponding to each frequency are established using the data collected at each frequency of the group hole water discharge test; The equations corresponding to each frequency are solved respectively to obtain the water conductivity and elastic water release coefficient of the detection area; the borehole hydrophobicity coefficient corresponding to each frequency is obtained according to the water conductivity and elastic water release coefficient of the detection area; the borehole hydrophobicity coefficient of the detection area is obtained according to the borehole hydrophobicity coefficient corresponding to each frequency.

2. The method for calculating the borehole hydrophobicity coefficient based on the underground group hole water discharge test according to claim 1 is characterized in that: The drain hole and monitoring hole include: The number of drainage holes in the group-hole drainage test is set to a first preset number, and the number of monitoring holes is set to a second preset number; wherein, the number of drainage holes shall not be less than 3, the number of monitoring holes shall not be less than 2, and the functions of the drainage holes and the monitoring holes can be converted to each other.

3. The method for calculating the borehole hydrophobicity coefficient based on the underground group hole water discharge test according to claim 1 is characterized in that: The group hole water discharge test includes at least two frequency tests, including: The number and positions of the drainage holes and monitoring holes used in each frequency test in the group-hole drainage experiment are not exactly the same.

4. The method for calculating the borehole hydrophobicity coefficient based on the underground group hole water discharge test according to claim 1 is characterized in that: The water pressure and flow rate data at each time point during the water discharge process are recorded, including: In each frequency of water release test, the uneven collection method is used to collect data. In the first period, the data collection interval is the first interval; in the second period, the data collection interval is the second interval; in the third period, the data collection interval is the third interval; after the third period, the data collection interval is the fourth interval until the data collection is completed.

5. The method for calculating the borehole hydrophobicity coefficient based on the underground group hole water discharge test according to claim 1 is characterized in that: The equations corresponding to each frequency are: Among them, s1, s2, …, s m is the total water level drop of each monitoring hole corresponding to a frequency; Q i is the flow rate of the ith drain hole; t1, t2, …, t m The time it takes for the water pressure of each monitoring hole corresponding to a frequency to reach stability; r i1 , r i2 ,…,r im is the distance between the ith drainage hole and each monitoring hole in a frequency; T is the water conductivity; μ * is the elastic water release coefficient.

6. The method for calculating the borehole hydrophobicity coefficient based on the underground group hole drainage test according to claim 1 is characterized in that: The equation groups corresponding to each frequency are solved respectively to obtain the water conductivity and elastic water release coefficient of the detection area, including: The equation group corresponding to each frequency is solved to obtain the water conductivity and elastic water release coefficient corresponding to each frequency; the water conductivity corresponding to each frequency is averaged to obtain the water conductivity of the detection area; the elastic water release coefficient corresponding to each frequency is averaged to obtain the elastic water release coefficient of the detection area.

7. The method for calculating the borehole hydrophobicity coefficient based on the underground group hole drainage test according to claim 1 is characterized in that: The method of obtaining the borehole hydrophobicity coefficient corresponding to each frequency according to the water conductivity and elastic water release coefficient of the detection area includes: Construct the relationship between the borehole hydrophobicity coefficient and the specific formula is: in, represents the borehole hydrophobicity coefficient corresponding to the jth monitoring hole in the ath frequency; T c and μ * c represent the water conductivity and elastic water release coefficient of the detection area respectively; represents the time it takes for the water pressure of the jth monitoring hole in the ath frequency to reach stability; r w Indicates the drilling radius; The drilling hydrophobicity coefficient corresponding to each frequency is obtained according to the drilling hydrophobicity coefficient relationship.

8. The method for calculating the borehole hydrophobicity coefficient based on the underground group hole drainage test according to claim 1 is characterized in that: The method of obtaining the borehole hydrophobicity coefficient of the detection area according to the borehole hydrophobicity coefficient corresponding to each frequency includes: The borehole hydrophobicity coefficients corresponding to each frequency are averaged to obtain the borehole hydrophobicity coefficient of the detection area.

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