Downward drilling water locking solving method based on controllable shock waves

Abstract

The invention discloses a downward drilling water locking solution method based on controllable shock waves, which comprises the following steps: S1, taking a target coal seam coal sample for laboratory test, and determining the minimum shock wave strength W and the shock frequency N required by coal seam pressure equalization; s2, inspecting a downward pre-pumping drill hole constructed in an underground roadway, and finding out a water locking drill hole; s3, delineating an outburst elimination range, and determining a water locking drill hole in the outburst elimination range for controllable shock wave treatment; and S4, according to the controllable shock wave construction effect of the previous outburst elimination range, the next outburst elimination range is constructed. The method has the beneficial effects that the downward drilling water locking phenomenon can be eliminated, soft low-permeability coal seam gas flowing is enhanced, and a gas high-pressure area is eliminated.

Description

Technical Field

[0001] The invention relates to the technical field of energy development, and in particular to a downward drilling water lock solution based on controllable shock waves. Background Art

[0002] As mining continues to deepen, the confining pressure on the coal rock mass increases significantly. Under the action of high confining pressure, the rock and coal mass exhibit ductile deformation characteristics, which are quite different from the properties exhibited by traditional coal rock mass.

[0003] According to classical fluid theory, as long as there is a pressure difference between the two ends of an object, the fluid will flow, and the flow will stop only when the pressure difference between the two ends of the object is reduced to zero. In underground coal seams, under the influence of confining pressure and gas pressure, gas flow requires a starting pressure to overcome the resistance generated by the flow. In particular, the starting pressure of gas flow in soft and low-permeability coal rocks will increase.

[0004] After pre-extraction of gas from soft and low-permeability coal seams, due to the existence of starting pressure, there will be a gas low-pressure area guided by the borehole and a gas high-pressure area formed by factors such as high stress and drilling trajectory deviation in the coal seam. If the gas high-pressure area is not properly handled, when the coal roadway is excavated into the gas high-pressure area, the gas in the working face will increase, and if it is large, it will cause coal and gas protrusion, and even cause a gas explosion.

[0005] The existing technologies are all to increase the permeability of the original coal seam. Due to factors such as the confining pressure and the gas pressure of the coal seam itself, the resulting fissures are difficult to preserve. In particular, the "water lock" effect of downward drilling will block the throat of the micro-cracks, making it difficult for the gas to flow under pressure.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art known to a person skilled in the art. Summary of the invention

[0007] The technical problem to be solved by the present invention is: how to solve the problem that the fissures generated due to factors such as confining pressure and gas pressure of the coal seam itself are difficult to preserve and the gas is difficult to release pressure and flow.

[0008] The present invention solves the above technical problems through the following technical means:

[0009] The method for solving the water lock of downward drilling based on controllable shock wave includes the following steps:

[0010] S1: Take the target coal seam coal sample for laboratory testing to determine the minimum shock wave intensity W and shock number N required for coal seam pressure equalization;

[0011] S2: Investigate the downward pre-extraction boreholes constructed in the underground tunnel to find the water-locked boreholes;

[0012] S3: Delineate the range of the sudden relief, and determine a water-locked borehole within the range for controllable shock wave treatment;

[0013] S4: According to the construction effect of the controllable shock wave in the previous burst elimination range, construct the next burst elimination range.

[0014] The present invention obtains the minimum shock wave intensity W and the number of shocks N required for the coal seam through laboratory tests, investigates the original boreholes by taking measures (such as pressure-maintaining coring to determine the residual gas amount, determining the gas pressure, and comparing the extraction amount of each borehole in the area, etc.), confirms the water-locked boreholes, delimits the range of the sudden outburst elimination near the water-locked boreholes, and performs controllable shock wave treatment on one of the water-locked boreholes to achieve the effect of increased production within the sudden outburst elimination range; finally, the construction parameters are adjusted according to the construction effect. The present invention can eliminate the water-locking phenomenon of downward boreholes, enhance the gas flow in soft and low-permeability coal seams, and eliminate the gas high-pressure area.

[0015] Preferably, in step S1, the ground test is a cyclic impact coal-rock dynamics experiment under triaxial stress or / and an X-CT scanning test, in which the intensity of new cracks appearing in the sample is W, and the number of impacts for through cracks to appear in the sample is N.

[0016] Preferably, in step S1, the minimum shock wave intensity W is 200 to 350 MPa, and the number of shocks N is 5 to 15 times.

[0017] Preferably, in step S2, the method for finding water-locked boreholes is: inspecting the gas concentration, negative pressure and temperature of the boreholes in the drilling site every shift; when the gas concentration of the borehole drops by more than 20%, the negative pressure increases and the temperature decreases, it is determined that the hole has a water-lock problem.

[0018] Preferably, in step S3, the bump elimination range is a range of 15-30 m in radius.

[0019] Preferably, in step S3, the controllable shock wave treatment is performed in the following manner: a controllable shock wave generating device is sent to the bottom of the hole, and the device carries N energetic rods with a shock wave intensity of W to perform the first shock wave operation, with N shock times.

[0020] Preferably, in step S4, if, within the previous sudden relief range, after the controllable shock wave construction, the pure amount Q of gas extraction from the construction drilling site main pipe is higher than 1.5 times the pure amount before construction, then the construction shock wave parameters within the next sudden relief range remain unchanged.

[0021] Preferably, in step S4, if within the previous sudden relief range, after the controlled shock wave construction, the pure amount Q of gas extracted from the construction drilling site main pipe is lower than 1.5 times the pure amount before construction, then within the next sudden relief range, 2N energy rods are used to carry out controlled shock wave operation construction.

[0022] Preferably, in step S4, if in the previous burst elimination range, there is still a gas concentration of more than 90% and the temperature difference between the borehole and the surrounding rock does not exceed 5 degrees Celsius, the next burst elimination range adopts a controllable shock wave operation with an intensity of 1.5W.

[0023] Preferably, in step S4, if in the previous sudden relief range, after the controlled shock wave construction, the gas concentration in the construction drilling site main pipe is lower than 0.8 times the flow rate before construction, the next sudden relief range uses an energetic rod with an intensity of 0.8W to perform controlled shock wave operation.

[0024] According to the construction results of the previous sudden relief range, the construction parameters in the next sudden relief range shall be adjusted in time to ensure that the gas high-pressure area is finally eliminated.

[0025] The advantages of the present invention are:

[0026] The present invention obtains the minimum shock wave intensity W and number of shocks N required for the coal seam through laboratory tests, investigates the original boreholes, confirms the water-locked boreholes, demarcates the range of the sudden relief near the water-locked boreholes, and performs controllable shock wave treatment on one of the water-locked boreholes to achieve the effect of increased production within the sudden relief range; finally, the construction parameters are adjusted according to the construction effect. The present invention can eliminate the water-locking phenomenon of boreholes (including horizontal, downward and upward boreholes or downward boreholes in coalbed methane wells) by means of the disturbance characteristics of different medium surfaces when the wave propagates in the formation, enhance the gas flow in soft and low-permeability coal seams, and eliminate the gas high-pressure area.

[0027] According to the construction results of the previous sudden relief range, the construction parameters in the next sudden relief range shall be adjusted in time to ensure that the gas high-pressure area is finally eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a downward drilling water lock solution based on controllable shock waves according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] Embodiment 1:

[0031] The method for solving the water lock of downward drilling based on controllable shock wave includes the following steps:

[0032] S1: Take the target coal seam coal sample for laboratory testing to determine the minimum shock wave intensity W and shock number N required for coal seam pressure equalization;

[0033] The ground test uses related basic parameter tests such as cyclic impact coal-rock dynamics experiment under triaxial stress and X-CT scanning test. Finally, the sample is loaded in the controllable shock wave coal seam permeability simulation experimental system. The system analyzes the experimental parameter thresholds and obtains the intensity of new cracks in the sample as W and the number of impacts of through cracks in the sample as N. Due to different coal qualities, the impact intensity is generally between 200 and 350MPa (±5MPa), and the number of impacts is generally between 5 and 15 times.

[0034] S2: Investigate the downward pre-extraction boreholes constructed in the underground tunnel to find the water-locked boreholes;

[0035] It should be noted that the downward pre-drainage borehole constructed in the underground tunnel is the original hole, and what needs to be done in this step is to find the water-locking borehole in the original hole.

[0036] The method to find water-locked boreholes is to inspect the gas concentration, negative pressure, and temperature of the boreholes in the drilling field every shift; when the gas concentration of the borehole drops by more than 20%, the negative pressure increases, and the temperature decreases, it is judged that the borehole has a water lock problem. Each shift can be 8 hours. The gas concentration drops by more than 20%, the negative pressure increases, and the temperature decreases generally occur at the same time.

[0037] Before examining the gas concentration, negative pressure and temperature of the borehole, the borehole opening needs to be sealed. In this embodiment, the borehole opening sealing device is a bag-type sealer. The outer end of the sealer is equipped with a gas concentration and temperature detection port.

[0038] S3: Delineate the range of the sudden relief, and determine a water-locked borehole within the range for controllable shock wave treatment;

[0039] The range of eliminating the sudden change is a range of 15-30m in radius. In this embodiment, the diameter is 30m, which can be selected as needed. The determined water lock borehole is preferably located at the center of the range of eliminating the sudden change.

[0040] Delineating the range of eliminating sudden gas means that after finding the water-locked borehole, a range with a diameter of 30m is delineated. As long as a water-locked borehole within the range is subjected to controllable shock wave treatment, the purpose of eliminating the high-pressure area of ​​coal seam gas can be achieved within the range of eliminating sudden gas. It is preferred to drill a hole in the middle of the delineated area to cause disturbance to the adjacent holes.

[0041] The method of carrying out controllable shock wave treatment is as follows: a controllable shock wave generating device is sent to the bottom of the hole. The device carries N energetic rods with a shock wave intensity of W to carry out the first shock wave operation with N shock times.

[0042] S4: According to the construction effect of the controllable shock wave in the previous burst elimination range, construct the next burst elimination range.

[0043] If, within the previous sudden relief range, after the controlled shock wave construction, the pure amount Q of gas extracted from the construction drilling site main pipe is higher than 1.5 times the pure amount before construction, it means that the intensity and frequency of the controlled shock wave are effective and can increase the gas extraction volume, then the construction shock wave parameters remain unchanged within the next sudden relief range.

[0044] If, within the previous sudden relief range, after the controlled shock wave construction, the pure amount Q of gas extracted from the construction drilling site main pipe is lower than 1.5 times the pure amount before construction, it means that the intensity and frequency of the controlled shock wave are limited and the impact intensity needs to be increased. In this case, 2N energy rods will be used for controlled shock wave operation within the next sudden relief range.

[0045] If there are still boreholes with gas concentration above 90% and borehole temperature close to the surrounding rock temperature in the previous burst elimination range, it means that the intensity and frequency of the controllable shock wave are limited and the shock intensity needs to be increased. The next burst elimination range shall adopt a controllable shock wave operation with an intensity of 1.5W.

[0046] If, within the previous sudden relief range, after the controlled shock wave construction, the gas concentration in the main pipe of the construction drilling site is lower than 0.8 times the flow rate before construction, it means that the intensity and frequency of the controlled shock wave may have shattered the borehole, and the debris has blocked the borehole. It is necessary to reduce the intensity of the shock wave, and use an energetic rod with a strength of 0.8W for controlled shock wave operation in the next sudden relief range.

[0047] According to the construction results of the previous sudden relief range, the construction parameters in the next sudden relief range shall be adjusted in time to ensure that the gas high-pressure area is finally eliminated.

[0048] This embodiment obtains the minimum shock wave intensity W and number of shocks N required for the coal seam through laboratory tests, investigates the original boreholes, confirms the water-locked boreholes, demarcates the range of the sudden elimination near the water-locked boreholes, and performs controllable shock wave treatment on one of the water-locked boreholes to achieve the effect of increased production within the sudden elimination range; finally, the construction parameters are adjusted according to the construction effect. The present invention can eliminate the water lock phenomenon of the downward borehole by means of the disturbance characteristics of different medium surfaces when the wave propagates in the formation, enhance the gas flow in the soft and low-permeability coal seam, and eliminate the gas high-pressure area.

[0049] 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 solution to water lock in downward drilling based on controllable shock waves, characterized in that: The following steps are involved: S1: Take the target coal seam coal sample for laboratory testing to determine the minimum shock wave intensity W and shock number N required for coal seam pressure equalization; S2: Investigate the downward pre-extraction boreholes constructed in the underground tunnel to find the water-locked boreholes; S3: Delineate the range of the sudden relief, and determine a water-locked borehole within the range for controllable shock wave treatment; S4: According to the construction effect of the controllable shock wave in the previous burst elimination range, construct the next burst elimination range.

2. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S1, the ground test is a cyclic impact coal-rock dynamics experiment under triaxial stress or / and an X-CT scanning test, a controllable shock wave coal seam permeability simulation experiment system. The system analyzes the experimental parameter thresholds and obtains the intensity of new cracks in the sample as W and the number of impacts N when through cracks appear in the sample.

3. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S1, the minimum shock wave intensity W is 200 to 350 MPa, and the number of shocks N is 5 to 15 times.

4. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S2, the method for finding water-locked boreholes is: each shift examines the gas concentration, borehole negative pressure, and temperature of the boreholes in the drilling site, and measures the residual gas content by taking core samples under pressure. When the borehole gas concentration drops by more than 20%, the negative pressure increases, and the temperature decreases, it is determined that the hole has a water-lock problem.

5. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S3, the collision elimination range is a range with a radius of 15-30m.

6. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S3, a controllable shock wave treatment is performed in the following manner: a controllable shock wave generating device is sent to the bottom of the hole, and the device carries N energetic rods with a shock wave intensity of W to perform the first shock wave operation, with N shock times.

7. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S4, if, in the previous sudden relief range, after the controllable shock wave construction, the pure amount Q of gas extraction from the construction drilling site main pipe is higher than 1.5 times the pure amount before construction, the construction shock wave parameters in the next sudden relief range remain unchanged.

8. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S4, if within the previous sudden relief range, after the controlled shock wave construction, the pure amount Q of gas extraction from the construction drilling site main pipe is lower than 1.5 times the pure amount before construction, then within the next sudden relief range, 2N energetic rods are used to carry out controlled shock wave operation.

9. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S4, if the gas concentration is still above 90% and the temperature difference between the borehole and the surrounding rock does not exceed 5 degrees Celsius in the previous burst elimination range, a controllable shock wave operation with an intensity of 1.5W is used in the next burst elimination range.

10. The downward drilling water lock solution based on controllable shock wave according to claim 1 is characterized in that: In step S4, if in the previous sudden relief range, after the controlled shock wave construction, the gas concentration in the construction drilling site main pipe is lower than 0.8 times the flow rate before construction, the next sudden relief range uses an energetic rod with an intensity of 0.8W to perform controlled shock wave operation.

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