A method and system for measuring gas content in coal seams at a long distance

Abstract

The present invention provides a method and system for long-distance gas content determination in coal seams, the method comprising: drilling to a target coal seam, withdrawing the drill, installing a closed coring device and sending it to the bottom of the hole; performing a coring operation using the closed coring device and recording a coring time t1 and a coring analysis time t2, thereby obtaining a coal sample for determination, collecting and saving a gas analysis amount W in the closed coring device 21 ; Collect and save the gas analysis amount W before crushing of the coal sample 22 ; crushing the measured coal sample, analyzing and saving the crushed gas analysis amount W3; processing the gas analysis amount W in the closed coring device with preset logic 21 , the gas analysis amount W before crushing 22 The crushed gas analysis amount W3 is used to determine the gas content. The present invention solves the technical problems of large gas content measurement error and short measurement distance.

Description

Technical Field

[0001] The invention relates to a gas prevention and control technology, and in particular to a method and system for measuring the gas content in a coal seam over a long distance. Background Art

[0002] Coal seam gas content is the basic parameter for calculating coal seam gas content and predicting and evaluating coal seam outburst danger, and is also the main indicator for testing the effectiveness of gas prevention and control measures. Rapid and accurate determination of coal seam gas content is of great significance for coal mine gas prevention and control work.

[0003] The invention patent with application number "CN201611155209.0" is a method for taking coal samples at near-horizontal, long-distance, fixed-point and sealed points in coal mines. It uses near-horizontal coal seam exploration directional holes to find out the fluctuation patterns of coal seams in the sampling area, and complete the design of sampling points and sampling directional holes; then, directional drilling is performed in sections to ensure that the directional holes are drilled to the sampling points along the designed trajectory, and then the pressure-maintaining and sealed sampling drill is used for sampling drilling and coal sampling under pressure until all sampling points are sampled. The existing patent determines the required sampling directional holes by exploring the sampling area. The sampling directional holes extend along the fluctuations of the coal seams and are arranged nearly horizontally. The sampling directional holes are composed of a casing hole section, a directional hole section and a sampling hole section. The casing hole section is close to the hole mouth, and the casing hole section is followed by directional hole sections and sampling hole sections that are alternately arranged in sequence. The trajectory setting of the sampling directional hole of the existing patent is different from that of the present application, and the existing patent does not disclose the specific processing logic of the free gas loss and adsorbed gas loss in the present application, which is significantly different from the technical solution of the present application. At the same time, the specification of the existing application discloses the use of the advantages of real-time measurement and control of the directional hole drilling trajectory and long-distance drilling and the pressure-resistant sealing characteristics of the pressure-maintaining closed sampling device to improve the measurement accuracy, which is very different from the technical implementation method of the present application using a fixed-point closed sampling device and a gas content determination method of closed sampling to calculate the gas loss to improve the detection distance and detection accuracy. In addition, the current domestic gas content determination sampling methods mainly include orifice slag connection, double-tube double-action, compressed air injection and other methods. Orifice slag connection is simple to operate and is the most used, but it cannot achieve fixed-point sampling, and it takes a long time at any time. The double-tube double-action method can ensure the quality of the sample, but the sampling time is very long, the gas content is lost during the sampling process, and the measurement error is large. Compressed air injection can both ensure sample quality and meet the time requirements for gas content determination, but it cannot be used for boreholes longer than 100 meters.

[0004] Many domestic experts and scholars have found through gas analysis and adsorption experiments that it is difficult to calculate the gas loss during the sampling process with a single gas content calculation model. The current model does not take into account the free gas loss during the sampling process when calculating the loss, resulting in generally low measurement results.

[0005] In summary, the existing technology has technical problems such as large gas content measurement error and short measurement distance. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to solve the technical problems of large gas content measurement error and short measurement distance.

[0007] The present invention adopts the following technical solutions to solve the above technical problems: A method for measuring the gas content in a coal seam at a long distance comprises:

[0008] S1. Drill to the target coal seam, withdraw the drill, install the closed coring device and send it to the bottom of the hole;

[0009] S2, using the closed coring device to perform coring operation and record the coring time t1 and the coring analysis time t2, thereby obtaining the coal sample for determination, collecting and saving the gas analysis amount W in the closed coring device 21 ;

[0010] S3, collecting and saving the gas analysis amount W of the coal sample before crushing 22 ;

[0011] S4, pulverizing the coal sample to be tested, and analyzing and saving the pulverized gas analysis amount W3;

[0012] S5, processing the gas analysis amount W in the closed coring device with preset logic 21 , the gas analysis amount W before crushing 22 and the crushed gas analysis amount W3, based on which the gas content is determined, the step S5 further includes:

[0013] S51, obtaining and processing preset sampling parameters using a preset gas analysis model to obtain the free gas loss amount W of the coal sample 11 ;

[0014] S52, using the preset gas analysis model to analyze the gas analysis amount W in the closed coring device 21 And the gas analysis amount W before crushing 22 , to obtain the adsorption gas loss W 12 ;

[0015] S53, according to the free gas loss amount W of the coal sample 11 And the adsorption gas loss W 12 The sampling loss amount W1 is obtained by processing;

[0016] S54, summing and processing the gas analysis amount W in the closed coring device 21 And the gas analysis amount W before crushing 22 , to obtain the natural analysis amount W2 before crushing;

[0017] S55, obtain and process the industrial analysis parameters of the coal sample to obtain the amount of gas adsorbed at normal pressure W C ;

[0018] S56, processing the sampling loss amount W1, the natural analysis amount before crushing W2, the crushing gas analysis amount W3 and the normal pressure adsorption gas amount W C , to obtain the gas content.

[0019] The present invention uses directional drilling, fixed-point closed sampling, coal sample crushing, and calculation of gas content to achieve long-distance coal seam gas content determination of more than 100 meters. The present invention calculates the sampling loss, the natural analysis amount before crushing, the crushing analysis amount, and the normal pressure adsorption gas amount to determine the gas content, thereby improving the accuracy of gas determination. The present invention uses a closed coring device for sampling, and the coal sample exposure time is short and the gas loss is small during the sampling process.

[0020] In a more specific technical solution, the drilling operation in step S1 adopts directional drilling construction.

[0021] In a more specific technical solution, the step S2 further includes:

[0022] S21, starting the timing from when the closed coring device is sent to the bottom of the hole and starts the fixed-point closed sampling;

[0023] S22, performing a closed coring operation with the closed coring device, and recording the coring time t1;

[0024] S23, before opening the closed coring device, recording the coring analysis time t2.

[0025] In a more specific technical solution, the closed coring operation includes: drilling, coring and sealing.

[0026] In a more specific technical solution, the step S3 further includes:

[0027] S31, opening the closed coring device to take out the coal sample for determination;

[0028] S32, collecting and saving the gas analysis amount W before crushing for the coal sample to be measured 22 .

[0029] In a more specific technical solution, the step S51 further includes:

[0030] S511. Test to obtain the original gas pressure p of the coal seam and the porosity V 孔 ;

[0031] S512: Process the original gas pressure p and porosity V of the coal seam using the following logic in the preset gas analysis model: 孔 , to obtain the free gas loss W of the coal sample 11 :

[0032]

[0033] , where p0 is the atmospheric pressure underground, T0 is the tunnel temperature, T is the coal seam temperature, p is the coal seam gas pressure, V 孔 is the porosity of the coal seam.

[0034] The present invention encapsulates the coal sample through a fixed-point closed coring device, reduces the gas loss in the sample, minimizes the loss in the sampling process, and then calculates the loss through coal seam gas pressure, gas analytical model and the like.

[0035] In a more specific technical solution, in step S52, the following logic in the preset gas analysis model is used to analyze the gas analysis amount W in the closed coring device: 21 And the gas analysis amount W before crushing 22 , to obtain the adsorption gas loss W12:

[0036]

[0037] , where t1 is the coring drilling time, t2 is the time from the start of coring to the opening of the closed coring device, and the adsorbed gas analysis time is

[0038] The present invention calculates the free gas loss and the adsorbed gas loss through the gas analysis model, obtains compensation data by calculating the free gas loss and the adsorbed gas loss, and the gas content calculation model introduces free gas compensation to make the measurement result more accurate. Through directional drilling construction, fixed-point closed sampling, and sampling loss model optimization, the coal seam gas content can be accurately measured.

[0039] In a more specific technical solution, in step S53, the free gas loss amount W of the coal sample is calculated by the following logic: 11 And the adsorption gas loss W 12 Sum:

[0040]

[0041] To obtain the sampling loss amount W1.

[0042] In a more specific technical solution, the industrial analysis parameters of the coal sample in step S55 include: adsorption constant a, adsorption constant b, and ash content.

[0043] In a more specific technical solution, a coal seam long-distance gas content measurement system includes:

[0044] The coring device is sent into the equipment, which is used to drill to the target coal seam, withdraw the drill, install the closed coring device and send it to the bottom of the hole;

[0045] The closed coring device is used to perform coring operations and record the coring time t1 and the coring analysis time t2, thereby obtaining coal samples for determination, collecting and saving the gas analysis amount W in the closed coring device. 21 , the enclosed coring device is connected to the coring device delivery device;

[0046] Gas analysis equipment before crushing, used to collect and save the gas analysis amount W before crushing of the coal sample 22 , the pre-crushing gas analysis equipment is connected to the closed coring device;

[0047] A crushing and analyzing device, used for crushing the coal sample to be measured, and analyzing and saving the crushed gas analysis amount W3, the crushing and analyzing device is connected to the pre-crushing gas analysis device;

[0048] Gas content measuring equipment, using preset logic to process the gas analysis volume W in the closed coring device 21 , the gas analysis amount W before crushing 22 and the crushed gas analysis amount W3, based on which the gas content is determined, the gas content determination device is connected to the crushing analysis device, and the gas content determination device also includes:

[0049] The free gas loss processing unit is used to obtain and process the preset sampling parameters to obtain the free gas loss of the coal sample W. 11 ;

[0050] Adsorption gas loss unit, used to analyze the gas analysis volume W in the closed coring device 21 And the gas analysis amount W before crushing 22 , to obtain the adsorption gas loss W 12 ;

[0051] The sampling loss processing unit is used to process the free gas loss W of the coal sample according to the free gas loss W of the coal sample. 11 And the adsorption gas loss W 12 The sampling loss amount W1 is obtained by processing, and the sampling loss amount processing unit is connected with the free gas loss processing unit and the adsorbed gas loss amount unit;

[0052] The natural analysis unit before crushing is used to sum and process the gas analysis amount W in the closed coring device. 21 And the gas analysis amount W before crushing 22 , to obtain the natural analysis amount W2 before crushing;

[0053] The atmospheric pressure adsorption gas processing unit is used to obtain and process the industrial analysis parameters of the coal sample to obtain the atmospheric pressure adsorption gas quantity W C ;

[0054] The crushed gas processing unit is used to process the sampling loss amount W1, the natural analysis amount before crushing W2, the crushed gas analysis amount W3 and the normal pressure adsorption gas amount W C , to obtain the gas content, the crushing gas processing unit is respectively connected to the sampling loss processing unit, the natural analysis unit before crushing, the crushing analysis equipment and the normal pressure adsorption gas processing unit.

[0055] Compared with the prior art, the present invention has the following advantages: the present invention uses directional drilling construction, fixed-point closed sampling, coal sample crushing, and calculation of gas content to achieve long-distance coal seam gas content determination of more than 100m. The present invention calculates the sampling loss, the natural analysis amount before crushing, the crushing analysis amount, and the normal pressure adsorption gas amount to determine the gas content, thereby improving the accuracy of gas determination. The present invention uses a closed coring device for sampling, and the coal sample exposure time is short and the gas loss is small during the sampling process.

[0056] The present invention encapsulates the coal sample through a fixed-point closed coring device, reduces the gas loss in the sample, minimizes the loss in the sampling process, and then calculates the loss through coal seam gas pressure, gas analytical model and the like.

[0057] The present invention calculates the free gas loss and the adsorbed gas loss through a gas analysis model, obtains compensation data by calculating the free gas loss and the adsorbed gas loss, and the gas content calculation model introduces free gas compensation to make the measurement result more accurate. Through directional drilling construction, fixed-point closed sampling, and sampling loss model optimization, the coal seam gas content can be accurately measured. The present invention solves the technical problems of large gas content measurement error and short measurement distance in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a basic flow chart of a method for long-distance gas content determination in a coal seam according to Example 1 of the present invention;

[0059] Figure 2 This is a schematic diagram of a detailed process of a method for determining gas content in a coal seam at a long distance according to Example 2 of the present invention;

[0060] Figure 3 Schematic diagram of gas content composition in Example 2 of the present invention. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Example 1

[0063] like Figure 1 As shown in the figure, the gas content determination process is divided into 4 steps:

[0064] S1. Directional drilling construction: In this embodiment, directional drilling is carried out to the target coal seam, the drill is withdrawn, a fixed-point closed coring device is installed, and the timing starts when the coring device is sent to the bottom of the hole.

[0065] S2, fixed-point closed sampling; in this embodiment, drilling, coring, and sealing are performed according to the method of use of the fixed-point closed coring device, the coring time t1 is recorded, and the coring device is taken out.

[0066] S3, coal sample crushing; in this embodiment, the time t2 is recorded before opening the closed coring device, and the gas analysis amount W in the coring device is recorded. 21 ; Crush the sample and record the gas analysis amount W before crushing 22 And crushing gas analysis W3

[0067] S4. Calculate gas content W a .

[0068] Example 2

[0069] like Figure 2 As shown in the figure, the detailed process of the method for determining the gas content in coal seams at a distance includes the following steps:

[0070] S1', drilling construction to the target coal seam;

[0071] S2', withdraw the drill, install the coring device and send it to the bottom of the hole;

[0072] S3', start coring;

[0073] S4', save the coring time t1;

[0074] S5', save the sample analysis time t2;

[0075] S6', coring is completed and the coring device is closed;

[0076] S7', taking out the coring device from the borehole;

[0077] S8', open the coring device and record the analytical volume W21 ;

[0078] S9', analyze and obtain the analysis amount W before crushing 21 ;

[0079] S10', analyze and obtain the sample crushing record analysis amount W3;

[0080] S11', calculate gas content W a .

[0081] like Figure 3 As shown, in this embodiment, the types of gas content measured include:

[0082] Gas content W a :

[0083] Gas content W a It consists of four parts: sampling loss amount W1, natural analysis amount before crushing W2, crushing analysis amount W3 and normal pressure adsorption gas amount Wc.

[0084] Sampling loss W1:

[0085] The sampling loss W1 is composed of the free gas loss of the coal sample during the sampling process W 11 and adsorption gas loss W 12 In this embodiment, the calculation method of the gas loss amount W1 is given as W 11 With W 12 sum:

[0086]

[0087] To obtain the gas loss W1.

[0088] Free gas loss W 11 It is calculated by the original gas pressure p of the tested coal seam and the porosity Vpore of the coal sample industrial analysis. 12 Calculated using a gas analytical model.

[0089]

[0090] Where: W 11 is the free gas loss, p0 is the underground atmospheric pressure, T0 is the tunnel temperature, T is the coal seam temperature, p is the coal seam gas pressure, and Vhole is the coal seam porosity.

[0091]

[0092] Where: W 12 is the adsorption gas loss, W 21is the gas analysis amount in the coring device, t1 is the coring drilling time, and t2 is the time from the start of coring to the opening of the sealed coring device. Since the coal sample is gradually stripped during the sampling process, the adsorbed gas analysis time during the sampling process is

[0093] Natural analysis amount before crushing W2:

[0094] The natural analysis volume W2 before crushing is obtained by the closed coring device W 21 The natural gas decomposition amount W before crushing 22 sum.

[0095] Crushing analysis volume W3:

[0096] The sample is crushed underground or on the ground to analyze the amount of gas.

[0097] Atmospheric pressure adsorption gas volume W C :

[0098] It is calculated through parameters such as adsorption constant a, adsorption constant b, ash content, etc. obtained through industrial analysis of coal samples.

[0099] By adopting a fixed-point closed sampling device in conjunction with a closed sampling method for determining gas content, a total of 24 samples were successfully taken to determine the gas content during an inspection of the effects of ground drilling and fracturing at the bottom parking lot of the Pan Yidong well. The maximum gas content in the original area of ​​the 13-1 coal seam was measured to be 24.8m3 / t, which is significantly higher than the value of 17m3 / t measured by the traditional gas content measurement method. This improves the accuracy of gas content measurement, and has high advancedness and promotion value.

[0100] In summary, the present invention has the following advantages over the prior art: the present invention uses four steps, namely, directional drilling, fixed-point closed sampling, coal sample crushing, and calculation of gas content, to achieve long-distance coal seam gas content determination of more than 100m. The present invention improves the accuracy of gas determination by calculating the sampling loss, the natural analysis amount before crushing, the crushing analysis amount, and the amount of gas adsorbed at normal pressure to determine the gas content. The present invention uses a closed coring device for sampling, and the coal sample exposure time is short and the gas loss is small during the sampling process.

[0101] The present invention encapsulates the coal sample through a fixed-point closed coring device, reduces the gas loss in the sample, minimizes the loss in the sampling process, and then calculates the loss through coal seam gas pressure, gas analytical model and the like.

[0102] The present invention calculates the free gas loss and the adsorbed gas loss through a gas analysis model, obtains compensation data by calculating the free gas loss and the adsorbed gas loss, and the gas content calculation model introduces free gas compensation to make the measurement result more accurate. Through directional drilling construction, fixed-point closed sampling, and sampling loss model optimization, the coal seam gas content can be accurately measured. The present invention solves the technical problems of large gas content measurement errors and short measurement distances in the prior art. The present invention solves the technical problems of large gas content measurement errors and short measurement distances in the prior art.

[0103] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring gas content in coal seams at a long distance, characterized in that: The method comprises: S1. Drill to the target coal seam, withdraw the drill, install the closed coring device and send it to the bottom of the hole; S2, using the closed coring device to perform coring operation and record the coring time t1 and the coring analysis time t2, thereby obtaining the coal sample for determination, collecting and saving the gas analysis amount W in the closed coring device 21 ; S3, collecting and saving the gas analysis amount W of the coal sample before crushing 22 ; S4, pulverizing the coal sample to be tested, and analyzing and saving the pulverized gas analysis amount W3; S5, processing the gas analysis amount W in the closed coring device with preset logic 21 , the gas analysis amount W before crushing 22 and the crushed gas analysis amount W3, based on which the gas content is determined, the step S5 further includes: S51, obtaining and processing preset sampling parameters using a preset gas analysis model to obtain the free gas loss amount W of the coal sample 11 ; Wherein, the step S51 further includes: S511. Test to obtain the original gas pressure p of the coal seam and the porosity V 孔 ; S512: Process the original gas pressure p and porosity V of the coal seam using the following logic in the preset gas analysis model: 孔 , to obtain the free gas loss W of the coal sample 11 : Among them, p0 is the underground atmospheric pressure, T0 is the tunnel temperature, T is the coal seam temperature, p is the original gas pressure of the coal seam, V 孔 is the coal seam porosity; S52, using the preset gas analysis model to analyze the gas analysis amount W in the closed coring device 21 And the gas analysis amount W before crushing 22 , to obtain the adsorption gas loss W 12 Wherein, in the step S52, the following logic in the preset gas analysis model is used to analyze the gas analysis amount W in the closed coring device: 21 And the gas analysis amount W before crushing 22 , to obtain the adsorption gas loss W 12 : Among them, t1 is the coring drilling time, t2 is the time from the start of coring to the opening of the closed coring device, and the adsorbed gas analysis time is S53, according to the free gas loss amount W of the coal sample 11 And the adsorption gas loss W 12 The sampling loss amount W1 is obtained by processing; wherein, in step S53, the free gas loss amount W of the coal sample is calculated by the following logic: 11 And the adsorption gas loss W 12 Sum: , to obtain the sampling loss amount W1; S54, summing and processing the gas analysis amount W in the closed coring device 21 And the gas analysis amount W before crushing 22 , to obtain the natural analysis amount W2 before crushing; S55, obtain and process the industrial analysis parameters of the coal sample to obtain the amount of gas adsorbed at normal pressure W C ; S56, processing the sampling loss amount W1, the natural analysis amount before crushing W2, the crushing gas analysis amount W3 and the normal pressure adsorption gas amount W C , to obtain the gas content.

2. A method for long-distance gas content determination in coal seams according to claim 1, characterized in that: The drilling operation in step S1 adopts directional drilling construction.

3. A method for long-distance gas content determination in coal seams according to claim 1, characterized in that: The step S2 further comprises: S21, starting the timing from when the closed coring device is sent to the bottom of the hole and starts the fixed-point closed sampling; S22, performing a closed coring operation with the closed coring device, and recording the coring time t1; S23, before opening the closed coring device, recording the coring analysis time t2.

4. A method for measuring gas content in a coal seam at a long distance according to claim 3, characterized in that: The closed coring operation includes: drilling, coring and sealing.

5. A method for measuring gas content in a coal seam at a long distance according to claim 1, characterized in that: The step S3 further comprises: S31, opening the closed coring device to take out the coal sample for determination; S32, collecting and saving the gas analysis amount W before crushing for the coal sample to be measured 22 .

6. A method for long-distance gas content determination in coal seams according to claim 1, characterized in that: The industrial analysis parameters of the coal sample in step S55 include: adsorption constant a, adsorption constant b, and ash content.

7. A coal seam long-distance gas content measurement system, used to perform a coal seam long-distance gas content measurement method according to any one of claims 1 to 6, characterized in that: The system comprises: The coring device is sent into the equipment, which is used to drill the target coal seam, withdraw the drill, install the closed coring device and send it to the bottom of the hole; The closed coring device is used to perform coring operations and record the coring time t1 and the coring analysis time t2, thereby obtaining coal samples for determination, collecting and saving the gas analysis amount W in the closed coring device. 21 , the enclosed coring device is connected to the coring device delivery device; Gas analysis equipment before crushing, used to collect and save the gas analysis amount W before crushing of the coal sample 22 , the pre-crushing gas analysis equipment is connected to the closed coring device; A crushing and analyzing device, used for crushing the coal sample to be measured, and analyzing and saving the crushed gas analysis amount W3, the crushing and analyzing device is connected to the pre-crushing gas analysis device; Gas content measuring equipment, using preset logic to process the gas analysis volume W in the closed coring device 21 , the gas analysis amount W before crushing 22 and the crushed gas analysis amount W3, based on which the gas content is determined, the gas content determination device is connected to the crushing analysis device, and the gas content determination device also includes: The free gas loss processing unit is used to obtain and process the preset sampling parameters to obtain the free gas loss of the coal sample W. 11 ; Adsorption gas loss unit, used to analyze the gas analysis volume W in the closed coring device 21 And the gas analysis amount W before crushing 22 , to obtain the adsorption gas loss W 12 ; The sampling loss processing unit is used to process the free gas loss W of the coal sample according to the free gas loss W of the coal sample. 11 And the adsorption gas loss W 12 The sampling loss amount W1 is obtained by processing, and the sampling loss amount processing unit is connected with the free gas loss processing unit and the adsorbed gas loss amount unit; The natural analysis unit before crushing is used to sum and process the gas analysis amount W in the closed coring device. 21 And the gas analysis amount W before crushing 22 , to obtain the natural analysis amount W2 before crushing; The atmospheric pressure adsorption gas processing unit is used to obtain and process the industrial analysis parameters of the coal sample to obtain the atmospheric pressure adsorption gas quantity W C ; The crushed gas processing unit is used to process the sampling loss amount W1, the natural analysis amount before crushing W2, the crushed gas analysis amount W3 and the normal pressure adsorption gas amount W C , to obtain the gas content, the crushing gas processing unit is respectively connected to the sampling loss processing unit, the natural analysis unit before crushing, the crushing analysis equipment and the normal pressure adsorption gas processing unit.

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