Coal seam drilling and sampling device, sampling method and gas loss measurement method

Abstract

The present application belongs to the technical field of coal seam sampling and gas measurement, and particularly provides a coal seam while-drilling sampling device, a sampling method and a gas loss measurement method, wherein the coal seam while-drilling sampling device comprises an outer drilling structure, a sealed pressure-maintaining sample storage device, a sampling drill bit, a double-power drilling machine, an outer drill rod, an inner drill rod and a sealed pressure-maintaining adjusting device; the coal seam while-drilling sampling method comprises the following specific steps: arranging the double-power drilling machine to a working area and assembling the equipment; performing non-sampling section drilling construction on the coal seam; drilling coal samples from the coal seam; taking out the coal samples and replacing the sealed pressure-maintaining sample storage device. The present application utilizes the while-drilling construction to continuously drill the coal samples, realizes the one-hole multi-section continuous sampling technology, improves the drilling sampling utilization rate, utilizes the sealed pressure-maintaining sample storage device to realize the process of drilling the coal samples from the original coal seam under the sealed pressure-maintaining environment, and utilizes the while-drilling sealed space gas emission velocity measuring device to realize the high-precision measurement of the gas loss.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal seam sampling and gas measurement, and particularly provides a coal seam sampling-while-drilling device, a sampling method and a gas loss measurement method. BACKGROUND

[0002] At present, the technologies and equipment for measuring coal seam gas parameters on the market mostly use drilling machines for drilling construction, use back-feeding drill pipes or sampling drill pipes to transport coal samples from the bottom of the hole to the hole mouth, and use coal sample tanks to complete the direct sampling method of hole mouth sampling. In this process, gas loss is difficult to avoid, and considering that different media, different time periods, different coal qualities and other factors will affect the gas desorption law, therefore, due to the problem of dispersion, the data finally calculated may have a large error, which directly affects the reliability of the laboratory measurement results.

[0003] In addition, in the direct sampling method, the coal sample taken by the hole mouth sampling is not necessarily the coal sample at the predetermined depth of the coal seam, and the sampling depth is limited by technology. During the drilling process of the coal sample, the desorbed gas is adsorbed on the surface of the drilling fissure, causing gas loss. At the same time, there is also the characteristic that a single drilling hole can only collect a single coal sample, which has the disadvantages of low sampling efficiency and high cost.

[0004] For the current method of directly determining the coal seam gas content in coal mines, the determination process of gas loss is affected by human factors, there is an error in the exposure time of the coal sample, and there is a reading error in the determination process of the underground gas desorption value, which leads to inaccurate determination of the gas loss and desorption of the coal sample, and finally, leads to a large error in the determination of the gas content of the coal sample.

[0005] Therefore, it is necessary to develop a new technology and device and a new method to solve the problems of low sampling efficiency, high cost, single drilling for collecting a single coal sample and inaccurate determination of gas content parameters at each stage in the traditional drilling method, and to optimize the construction method of long-distance continuous coal sampling in complex environments and the new method of coal seam gas content determination. SUMMARY

[0006] To solve the above technical problems, the technical scheme adopted by the present application is: a coal seam drilling and sampling device, comprising an outer drilling structure, a sealed pressure maintaining and sample storing device, a sampling drill bit, a double-power drilling machine, an outer drill rod, an inner drill rod and a sealed pressure maintaining and adjusting device, the inner drill rod is coaxially assembled in the inner part of the outer drill rod, and the outer drill rod and the inner drill rod are both assembled on the double-power drilling machine, the outer drilling structure and the sampling drill bit are respectively assembled at the front ends of the outer drill rod and the inner drill rod, a drilling drill bit is arranged at the front end of the outer drilling structure, a central valve plate is arranged at the front end of the drilling drill bit, the sealed pressure maintaining and sample storing device is arranged at the front end of the inner drill rod and connected with the sampling drill bit, the sample cut by the sampling drill bit falls into the sealed pressure maintaining and sample storing device, a sealed pressure maintaining device is assembled at the rear part of the side wall of the sampling drill bit, and the sealed pressure maintaining device is connected with the sealed pressure maintaining and adjusting device through a pipeline.

[0007] Further, the sealed pressure maintaining device is composed of a plurality of high-pressure sealed pressure maintaining capsules, the plurality of high-pressure sealed pressure maintaining capsules are sleeved at the rear part of the side wall of the sampling drill bit, a second air guide pipe is arranged in the inner part of the inner drill rod, one end of the second air guide pipe is connected with the sealed pressure maintaining and adjusting device, and the other end of the second air guide pipe is provided with a plurality of branch openings, and the plurality of branch openings are connected with the plurality of high-pressure sealed pressure maintaining capsules one by one.

[0008] Further, the sealed pressure maintaining and sample storing device is composed of a sealed sample storing air chamber and an elastic pressure maintaining capsule, the sealed sample storing air chamber is a cylindrical structure, a sample storing air chamber valve plate is assembled at the front end of the sealed sample storing air chamber, and the elastic pressure maintaining capsule is assembled at the rear end of the outer surface of the sealed sample storing air chamber, a first air guide pipe is arranged in the inner part of the inner drill rod, and both ends of the first air guide pipe are connected with the sealed pressure maintaining and adjusting device and the elastic pressure maintaining capsule respectively.

[0009] A coal seam drilling and sampling method is applied to the coal seam drilling and sampling device in embodiment one, and the specific steps are as follows:

[0010] Step one, arranging the double-power drilling machine to the working area and assembling the equipment;

[0011] Step two, performing non-sampling section drilling construction on the coal seam;

[0012] Step three, drilling coal samples from the coal seam;

[0013] Open the center valve plate of the drilling bit, operate the outer power load device, retreat the outer drilling structure to the back of the closed pressure maintaining device, operate the closed pressure maintaining adjusting device, inflate the elastic pressure maintaining capsule and the high pressure closed pressure maintaining capsule, when the elastic pressure maintaining capsule and the high pressure closed pressure maintaining capsule are fully inflated, adjust the closed pressure maintaining adjusting system, keep the capsule gas pressure, form the closed pressure maintaining sampling space, open the sample storage air chamber valve plate, start the inner power load device drilling function, start the sampling section drilling and sampling operation, drill the coal sample through the sample storage air chamber valve plate into the closed sample storage air chamber, when the sampling section drilling and sampling operation are completed, close the sample storage air chamber valve plate, stop the inner power load device drilling function, complete the single sampling operation.

[0014] Step four, take out the coal sample, and replace the closed pressure maintaining sample storage device.

[0015] Step five, repeat the operation of step three and step four to complete multiple continuous sampling for a single borehole.

[0016] Further, the specific way of step four is to operate the closed pressure maintaining adjusting device to deflate the elastic pressure maintaining capsule and the high pressure closed pressure maintaining capsule, when the deflation is completed, operate the outer power load device to send the outer drilling structure to the front section of the borehole, at the same time, operate the inner power load device to withdraw the sampling drill bit and the closed pressure maintaining sample storage device with the coal sample into the outer drilling structure, then close the center valve plate, continue to withdraw the closed pressure maintaining sample storage device until it is completely withdrawn from the borehole through the outer drilling rod.

[0017] A gas loss measurement method based on the coal seam sampling while drilling method in embodiment two.

[0018] The front end of the inner side wall of the sampling drill bit is embedded with a gas emission velocity measuring sensor, and the front end position of the inner side wall of the closed sample storage air chamber is embedded with a gas emission velocity measuring sensor.

[0019] The gas emission velocity measuring sensor can identify the pressure, temperature and other conventional parameters of the gas in the borehole and the sample storage air chamber, and is provided with a built-in timing module and a storage module, and can obtain the gas emission velocity data in the sample storage air chamber through operation according to the identified parameters, and record the data in the storage module.

[0020] The specific process is as follows:

[0021] When the rotation function of the outer power load device of the double power drilling machine is stopped, the time t1 is recorded, and when the drilling function of the inner power load device is stopped, the time t2 is recorded.

[0022] When the inner layer pressure maintaining drilling sampling structure is withdrawn, the gas emission rate measuring sensor on the inner wall of the sampling drill bit is removed, and after the coal sample gas desorption amount and residual amount are measured in the laboratory, the gas emission rate measuring sensor on the inner wall of the closed sample storage gas chamber is removed, the gas emission rate is measured by the computer reading the measuring device, that is, at t1, the gas emission rate of the sampling section K1, the gas emission rate of the sample storage chamber K2, at t2, the gas emission rate of the sampling section K3, the gas emission rate of the sample storage chamber K4;

[0023] The gas loss amount calculation formula of the borehole sampling is:

[0024] Formula 1: V 损 =V 钻 -V 气室 ;

[0025] Formula 2: V 钻 =Q 钻 ·Δt=(K3-K1)·S 钻 ·(t2-t1);

[0026] Formula 3: V 气室 =Q 气室 ·Δt=(K4-K2)·S 钻 ·(t2-t1);

[0027] In the formula:

[0028] V 损 is the sampling gas loss amount (m³);

[0029] V 钻 is the sampling section gas emission amount (m³);

[0030] V 气室 is the gas emission amount of the sample storage chamber (m³);

[0031] Q 钻 is the gas amount through the sampling section borehole per unit time (m³ / min);

[0032] Q 气室 is the gas amount through the sample storage chamber per unit time (m³ / min);

[0033] S 钻 is the sampling section borehole cross-sectional area, m²;

[0034] S 气室 is the sample storage chamber cross-sectional area, m²;

[0035] K1 is the t1 sampling section gas emission rate (m³ / min·㎡);

[0036] K2 is the t1 sample storage chamber gas emission rate (m³ / min·㎡);

[0037] K3 is the t2 sampling section gas emission velocity (m³ / min·㎡);

[0038] K4 is the t2 storage gas chamber gas inflow velocity (m³ / min·㎡);

[0039] Through theoretical calculation, the coal seam gas loss amount V in the sampling process is determined 损 .

[0040] Further, according to the borehole sampling gas loss amount calculation formula, the operation flow is coded into the firmware device.

[0041] The beneficial effects of using the present application are:

[0042] The present application utilizes continuous drilling of coal samples with drilling operation, realizes the process of drilling coal samples in the original coal seam with continuous borehole drilling while drilling, greatly reduces the exposure time of drilling coal samples, eliminates the movement distance of drilling coal samples, eliminates the hidden dangers of work and human operation errors of traditional orifice drilling coal samples, reduces the drilling construction amount, avoids the problem of drilling trajectory deviation caused by complete drilling, realizes the continuous sampling technology of one hole and multiple segments, improves the utilization rate of drilling sampling;

[0043] The elastic pressure maintaining function of the closed pressure maintaining and sample storage device and the high pressure closed pressure maintaining capsule of the closed pressure maintaining device are utilized to perform closed pressure maintaining of the drilling coal sample environment, realize the process of drilling coal samples in the original coal seam under the closed pressure maintaining environment, ensure the closed isolation of the sampling space and the outside world, reduce the loss of gas desorption amount of drilling coal samples, improve the accuracy of gas desorption amount determination, and improve the authenticity of the original coal seam gas parameters;

[0044] The drilling closed space gas emission velocity determination device is utilized to determine the gas flow velocity in the borehole and the gas flow velocity in the closed sample storage chamber during the sampling process, the gas loss amount during the sampling process is determined through calculation, the human error value of drilling cuttings sampling gas desorption amount orifice loss and borehole fracture re-adsorption loss and loss amount is eliminated, and the accuracy of coal seam gas content is improved. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a schematic diagram of the sampling drill bit received in the internal state of the outer drilling structure of the present application;

[0046] Figure 2 is a schematic diagram of the sampling drill bit in the sampling operation state of the present application;

[0047] The reference signs include: 1, outer drilling structure; 2, closed pressure storage sample device; 3, drilling drill bit; 4, sampling drill bit; 5, double power drilling machine; 501, outer power load device; 502, inner power load device; 6, closed pressure device; 601, high-pressure closed pressure capsule; 7, elastic pressure capsule; 801, first air guide pipe; 802, second air guide pipe; 9, center valve plate; 10, sample storage gas chamber valve plate; 11, closed sample storage gas chamber; 1201, first gas emission rate measuring sensor; 1202, second gas emission rate measuring sensor; 13, outer drill pipe; 14, inner drill pipe; 15, coal sample; 16, coal seam; 17, closed pressure adjusting device. DETAILED DESCRIPTION

[0048] The application will be described in detail below with reference to the accompanying drawings.

[0049] Example 1

[0050] Reference Figure 1 And Figure 2 A coal seam while-drilling sampling device includes an outer drilling structure 1, a closed pressure storage sample device 2, a sampling drill bit 4, a double power drilling machine 5, an outer drill pipe 13, an inner drill pipe 14, and a closed pressure adjusting device 17. The inner drill pipe 14 is coaxially assembled inside the outer drill pipe 13, and the outer drill pipe 13 and the inner drill pipe 14 are both assembled on the double power drilling machine 5. The outer drilling structure 1 and the sampling drill bit 4 are respectively assembled at the front ends of the outer drill pipe 13 and the inner drill pipe 14. The front end of the outer drilling structure 1 is provided with a drilling drill bit 3, and the front end port of the drilling drill bit 3 is provided with a center valve plate 9. The closed pressure storage sample device 2 is arranged at the front end of the inner drill pipe 14 and connected with the sampling drill bit 4. The sample cut by the sampling drill bit 4 falls into the closed pressure storage sample device 2. The closed pressure storage sample device 2 is arranged at the front end of the inner drill pipe 14 and connected with the sampling drill bit 4. The sample cut by the sampling drill bit 4 falls into the closed pressure storage sample device 2. The rear part of the side wall of the sampling drill bit 4 is provided with a closed pressure device 6, and the closed pressure device 6 is connected with the closed pressure adjusting device 17 through a pipeline.

[0051] Specifically, the inner part of the outer drill pipe 13 is arranged with annular track frames at equal intervals, and the inner drill pipe 14 is slidably assembled in the inner part of the outer drill pipe 13 through the annular track frames.

[0052] Preferably, the closed pressure adjusting device 17 uses nitrogen as a gas source and uses a high-pressure gas pump as a pressurized gas supply equipment.

[0053] The closed pressure device 6 is composed of a plurality of high-pressure closed pressure capsules 601, which are sleeved on the rear part of the side wall of the sampling drill bit 4. The inner part of the inner drill pipe 14 is arranged with a second air guide pipe 802, one end of the second air guide pipe 802 is connected with the closed pressure adjusting device 17, and the other end of the second air guide pipe 802 is provided with a plurality of branch ports, which are connected with the plurality of high-pressure closed pressure capsules 601 one by one.

[0054] The closed pressure-maintaining sample storage device 2 is composed of a closed sample storage gas chamber 11 and an elastic pressure-maintaining capsule 7. The closed sample storage gas chamber 11 is in a cylindrical structure. The front end of the closed sample storage gas chamber 11 is equipped with a sample storage gas chamber valve plate 10. The rear end of the outer surface of the closed sample storage gas chamber 11 is equipped with the elastic pressure-maintaining capsule 7. The inner layer drill rod 14 is internally disposed with a first air guide pipe 801. The two ends of the first air guide pipe 801 are respectively connected with a closed pressure-maintaining adjusting device 17 and the elastic pressure-maintaining capsule 7.

[0055] The double-power drilling machine 5 is internally provided with an outer layer power load device 501 and an inner layer power load device 502. The outer layer power load device 501 and the inner layer power load device 502 are respectively connected with the outer layer drill rod 13 and the inner layer drill rod 14.

[0056] Example Two

[0057] A coal seam while-drilling sampling method applies the coal seam while-drilling sampling device in Example One. The specific steps are as follows:

[0058] Step One, arrange the double-power drilling machine 5 to the working area and perform equipment assembly.

[0059] Specifically, at the drilling site, the adjustable drilling bit 3 with the center valve plate 9 is connected with the outer layer drill rod 13 to form the outer layer drilling structure 1.

[0060] The sampling drill bit 4 is connected with the inner layer drill rod 14. The closed sample storage gas chamber 11 containing the sample storage gas chamber valve plate 10 is connected with the elastic pressure-maintaining capsule 7 to form the closed pressure-maintaining sample storage device 2.

[0061] The closed pressure-maintaining sample storage device 2 is connected with the sampling drill bit 4 through the track groove to form the inner layer pressure-maintaining drilling sampling structure.

[0062] Step Two, perform non-sampling section drilling construction to the coal seam 16.

[0063] Specifically, start the double-power drilling machine 5, open the outer layer power load device 501 drilling function, and at the same time, open the inner layer power load device 502 propulsion function to push the inner layer pressure-maintaining drilling sampling structure to enter the borehole along with the outer layer drilling structure.

[0064] Step Three, drill the coal sample 15 from the coal seam.

[0065] Specifically, the outer drilling structure 1 is constructed to the designed non-sampling section position before the sampling section, the rotation function of the outer power load device 501 of the double-power drilling machine 5 is stopped, the central valve plate 9 of the drilling bit 3 is opened, the outer power load device 501 is operated, the outer drilling structure 1 is retreated to the rear of the closed pressure maintaining device, the closed pressure maintaining adjusting device 17 is operated, the elastic pressure maintaining capsule 7 and the high-pressure closed pressure maintaining capsule 601 are inflated, when the elastic pressure maintaining capsule 7 and the high-pressure closed pressure maintaining capsule 601 are fully inflated, the closed pressure maintaining adjusting system 17 is adjusted to maintain the capsule gas pressure, the closed pressure maintaining sampling space is formed, the sample storage gas chamber valve plate 10 is opened, the drilling function of the inner power load device 502 is started, the sampling section drilling and sampling operation is started, the coal sample 15 is drilled by the sampling drilling bit 4 and enters the closed sample storage gas chamber 11 through the sample storage gas chamber valve plate 10, when the sampling section drilling and sampling construction is completed, the sample storage gas chamber valve plate 10 is closed, the drilling function of the inner power load device 502 is stopped, the single sampling operation is completed, and the time t2 is recorded.

[0066] Step four, the coal sample 15 is taken out, and the closed pressure maintaining sample storage device 2 is replaced;

[0067] Specifically, the closed pressure maintaining adjusting device 17 is operated to deflate the elastic pressure maintaining capsule 7 and the high-pressure closed pressure maintaining capsule 601, after complete deflation, the outer power load device 501 is operated to send the outer drilling structure 1 to the front section of the drilling hole, at the same time, the inner power load device 502 is operated to retreat the sampling drilling bit 4 and the closed pressure maintaining sample storage device 2 containing the coal sample 15 to the outer drilling structure 1, then the central valve plate 9 is closed, and the retreat of the closed pressure maintaining sample storage device 2 is continued until it completely exits the drilling hole through the outer drilling rod 13.

[0068] The new closed pressure maintaining sample storage device 2 is replaced, and is sent to the front section position of the outer drilling structure 1 through the inner power load device 502, and the preparation work for the next sampling is completed.

[0069] Step five, the operation of steps three and four is repeated to complete multiple continuous samplings for a single drilling hole.

[0070] Specifically, during the operation process of step four, the operation of step two is simultaneously implemented to construct the non-sampling section drilling hole, that is, the implementation of step four does not affect the implementation of step two.

[0071] Example three

[0072] A gas loss measurement method based on the coal seam sampling-while-drilling method in example two.

[0073] The first gas emission velocity measuring sensor 1201 is embedded in the front end of the inner side wall of the sampling drilling bit 4, and the second gas emission velocity measuring sensor 1202 is embedded in the front end position of the inner side wall of the closed sample storage gas chamber 11.

[0074] The first gas emission rate measuring sensor 1201 and the second gas emission rate measuring sensor 1202 are turned on at the same time when the inner power load device 502 is turned on to promote the function.

[0075] The gas emission rate measuring sensor can identify the pressure, temperature and other conventional parameters of the gas in the borehole and the sealed sample storage chamber 11, and has a built-in timing module and a storage module. According to the identified parameters, the gas emission rate data in the sample storage chamber can be obtained through calculation, and the data is recorded in the storage module.

[0076] A gas loss measurement method, the specific process is as follows:

[0077] When the rotation function of the outer power load device 501 of the double-power drilling machine 5 is stopped, the time t1 is recorded, and when the drilling function of the inner power load device 502 is stopped, the time t2 is recorded;

[0078] When the inner pressure-maintaining drilling sampling structure is exited, the first gas emission rate measuring sensor 1201 is removed, and after the laboratory measures the gas desorption amount and residual amount of the coal sample, the second gas emission rate measuring sensor 1202 is removed. The gas emission rate is measured by a computer reading measuring device, that is, at time t1, the gas emission rate K1 of the sampling section is K1, the gas emission rate K2 of the sample storage chamber is K2, at time t2, the gas emission rate K3 of the sampling section is K3, and the gas emission rate K4 of the sample storage chamber is K4.

[0079] The formula for calculating the gas loss amount of the in-hole sampling is:

[0080] Formula 1: V 损 = V 钻 -V 气室 ;

[0081] Formula 2: V 钻 = Q 钻 · Δt = (K3-K1)· S 钻 · (t2-t1);

[0082] Formula 3: V 气室 = Q 气室 · Δt = (K4-K2)· S 钻 · (t2-t1);

[0083] In the formula:

[0084] V 损 is the gas loss amount of the sampling (m³);

[0085] V 钻 is the gas emission amount of the sampling section (m³);

[0086] V 气室 is the gas emission amount of the sample storage chamber (m³);

[0087] Q 钻 Q is the amount of gas passing through the sampling section borehole per unit time (m³ / min);

[0088] Q 气室 Q is the amount of gas passing through the sampling section borehole per unit time (m³ / min);

[0089] S 钻 S is the cross-sectional area of the sampling section borehole, m²;

[0090] S 气室 S is the cross-sectional area of the sampling section borehole, m²;

[0091] K1 is the gas emission rate of t1 sampling section (m³ / min·㎡);

[0092] K2 is the gas emission rate of t1 sampling section (m³ / min·㎡);

[0093] K3 is the gas emission rate of t2 sampling section (m³ / min·㎡);

[0094] K4 is the gas emission rate of t2 sampling section (m³ / min·㎡);

[0095] Through theoretical calculation, the amount of coal seam gas loss V 损 during sampling is determined.

[0096] The above operation process is coded into a firmware device (using a mature single-chip coding method on the market), which can realize the determination of the amount of gas loss in the borehole.

[0097] The above is only a preferred embodiment of the present application. For those skilled in the art, according to the idea of the present application, many changes can be made in the specific implementation and application range, as long as these changes do not deviate from the concept of the present application, and all belong to the protection scope of the present application.

Claims

1. A method for calculating gas loss, based on a coal seam sampling while drilling method and employing a coal seam sampling while drilling device; Coal seam sampling while drilling equipment, including an outer drilling structure, a sealed pressure-maintaining sample storage device, a sampling drill bit, a dual-power drilling rig, an outer drill rod, an inner drill rod and a sealed pressure-maintaining adjustment device. The inner drill rod is coaxially assembled inside the outer drill rod, and the outer drill rod and the inner drill rod are both assembled on the dual-power drilling rig. The outer drilling structure and the sampling drill bit are respectively assembled at the front ends of the outer drill rod and the inner drill rod. The front end of the outer drilling structure is provided with a drilling bit, and the front port of the drilling bit is provided with a center valve plate. The sealed pressure-maintaining sample storage device is provided at the front end of the inner drill rod and is connected to the sampling drill bit. The sample cut by the sampling drill bit falls into the sealed pressure-maintaining sample storage device. The rear part of the side wall of the sampling drill bit is equipped with a sealed pressure-maintaining device, and the sealed pressure-maintaining device is connected to the sealed pressure-maintaining adjustment device through a pipeline. The specific steps of coal seam sampling while drilling are as follows: Step 1: Arrange the dual-power drilling rig in the work area and assemble the equipment; Step 2: Drilling a non-sampling section into the coal seam; Step 3: Drilling coal samples from the coal seam; Open the central valve plate of the drilling bit, operate the outer dynamic load device, retreat the outer drilling structure to the rear of the closed pressure maintaining device, operate the closed pressure maintaining regulating device, inflate the elastic pressure maintaining capsule and the high-pressure closed pressure maintaining capsule, and when the elastic pressure maintaining capsule and the high-pressure closed pressure maintaining capsule are fully expanded, adjust the closed pressure maintaining regulating system to maintain the gas pressure in the capsule to form a closed pressure maintaining sampling space, open the valve plate of the sample storage chamber, start the drilling function of the inner dynamic load device, start the sampling section drilling and sampling operation, and use the sampling drill bit to drill the coal sample through the valve plate of the sample storage chamber to enter the closed sample storage chamber. After the sampling section drilling and sampling construction are completed, close the valve plate of the sample storage chamber, stop the drilling function of the inner dynamic load device, and complete the single sampling operation; Step 4: Take out the coal sample and replace the sealed pressure-maintaining sample storage device; Step 5: Repeat the operations of steps 3 and 4 to complete multiple consecutive samplings for a single borehole; The gas loss amount calculation method is characterized by: A gas outflow velocity measuring sensor is embedded in the front end of the inner wall of the sampling drill bit, and a gas outflow velocity measuring sensor is embedded in the front end of the inner wall of the sealed sample storage chamber; The gas outflow velocity measuring sensor can identify conventional parameters such as pressure and temperature of gas in the borehole and the sample gas storage chamber, and has a built-in timing module and a storage module. It can obtain gas outflow velocity data in the sample gas storage chamber through calculation based on the identified parameters and record the data in the storage module; The specific process is as follows: When the rotation function of the outer power load device of the dual-power drilling rig is stopped, the time t1 is recorded; when the drilling function of the inner power load device is stopped, the time t2 is recorded; When exiting the inner layer pressure-maintaining drilling sampling structure, remove the gas outflow velocity measuring sensor on the inner side wall of the sampling drill bit. After the laboratory measures the desorption amount and residual amount of the coal sample gas, remove the gas outflow velocity measuring sensor on the inner side wall of the closed sample storage chamber. The gas outflow velocity is measured by a computer reading measuring device. That is, at time t1, the gas outflow velocity of the sampling section is K1, and the inflow velocity of the sample storage chamber is K2. At time t2, the gas outflow velocity of the sampling section is K3, and the inflow velocity of the sample storage chamber is K4. The calculation formula for gas loss from hole sampling is: Formula 1: V 损 =V 钻 -V 气室 ; formula 2:V 钻 =Q 钻 ·Δt=(K3-K1)·S 钻 ·(t2-t1); Formula 3: V 气室 =Q 气室 ·Δt=(K4-K2)·S 钻 (t2 - t1); Where: V 损 is the sampling gas loss (m³); V 钻 is the gas outflow volume of the sampling section (m³); V 气室 is the gas influx into the sample gas chamber (m³); Q 钻 is the amount of gas passing through the sampling section borehole per unit time (m³ / min); Q 气室 is the amount of gas passing through the sample storage chamber per unit time (m³ / min); S 钻 is the cross-sectional area of ​​the sampling section borehole, m2; S 气室 is the cross-sectional area of ​​the sample storage chamber, m2; K1 is the gas outflow velocity at sampling section t1 (m³ / min·㎡); K2 is the gas inflow rate of the sample storage chamber at t1 (m³ / min·㎡); K3 is the gas outflow velocity at the sampling section t2 (m³ / min·㎡); K4 is the gas inflow rate of the sample storage chamber t2 (m³ / min·㎡); Through theoretical calculation, the coal seam gas loss V during sampling is determined 损 .

2. A method for calculating gas loss according to claim 1, characterized in that: The sealed pressure-maintaining device is composed of a plurality of high-pressure sealed pressure-maintaining capsules, which are mounted on the rear part of the side wall of the sampling drill bit. A second air duct is disposed inside the inner drill rod, one end of the second air duct is connected to the sealed pressure-maintaining adjustment device, and the other end of the second air duct is provided with a plurality of branch ports, which are connected one-to-one with the plurality of high-pressure sealed pressure-maintaining capsules.

3. The method for calculating gas loss according to claim 1, characterized in that: The sealed pressure-maintaining sample storage device is composed of a sealed sample storage air chamber and an elastic pressure-maintaining capsule. The sealed sample storage air chamber is a cylindrical structure. The front end of the sealed sample storage air chamber is equipped with a sample storage air chamber valve plate, and the rear end of the outer surface of the sealed sample storage air chamber is equipped with an elastic pressure-maintaining capsule. A first air guide tube is deployed inside the inner drill rod, and both ends of the first air guide tube are respectively connected to the sealed pressure-maintaining adjustment device and the elastic pressure-maintaining capsule.

4. The method for calculating gas loss according to claim 1, wherein: The specific method of step four is to operate the closed pressure maintaining adjustment device to unload the elastic pressure maintaining capsule and the high-pressure closed pressure maintaining capsule. After the pressure is completely unloaded, operate the outer dynamic load device to send the outer drilling structure to the front section of the drilling hole. At the same time, operate the inner dynamic load device to withdraw the sampling drill bit and the closed pressure maintaining sample storage device containing the coal sample into the outer drilling structure, and then close the center valve plate and continue to retract the closed pressure maintaining sample storage device until it passes through the outer drill rod and completely exits the drilling hole.

5. The method for calculating gas loss according to claim 1, characterized in that: According to the calculation formula of the gas loss amount of the hole sampling, the operation process is encoded into the firmware device.

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