Real-time judgment method for coal gangue in horizontal section of coal bed gas

Abstract

The invention belongs to the field of coal and gangue mining, and relates to a coal bed gas horizontal section coal and gangue real-time judgment method which comprises the following steps: step 100, lowering a horizontal section drilling tool to obtain azimuth gamma data of a coal bed gas horizontal section; step 200, generating an azimuth gamma curve according to the azimuth gamma data in combination with corresponding well depth data; step 300, observing an inflection point of the azimuth gamma curve, and pre-judging drilling encountering coal gangue; 400, the torque and the drilling time are observed at a wellhead, and coal gangue encountering drilling is judged; 500, it is determined that the drilling track is located in the coal bed gas horizontal section, the drilling track is adjusted, and drilling continues; and step 600, repeating the steps 300 to 500. The horizontal section drilling tool penetrates and drills in a target coal seam, whether coal gangue is drilled or not is detected in real time by means of an orientation gamma detection tool in the horizontal section drilling tool, and after it is judged that the coal gangue is drilled, drilling parameters are adjusted in time, the underground collapse degree is reduced, and safe drilling of the horizontal section is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of coal gangue mining, specifically relating to a method for real-time determination of coal gangue in horizontal sections of coalbed methane. Background Technology

[0002] Coalbed methane (CBM) extraction depths typically exceed 300 meters underground. Horizontal CBM wells are characterized by small well site footprints, large controlled reservoir layers, and high gas production. However, horizontal well drilling presents challenges such as difficulty in safely entering the well window, low drilling success rate, and high risks of collapse and stuck pipe.

[0003] Currently, azimuth gamma detection tools are often used to detect gamma values ​​in specific directions of the formation in real time to determine the position of the drill bit in the coal seam, prevent the drill bit from drilling out of the coal seam, and improve the drilling rate of horizontal coal seams. However, the efficiency of judging the encounter of coal gangue in horizontal coal seams is low, and wellbore collapse is prone to occur, which has always plagued the safe and rapid drilling of long horizontal sections of coalbed methane. Summary of the Invention

[0004] The purpose of this invention is to provide a method for real-time determination of coal gangue in the horizontal section of coalbed methane, so as to overcome the above-mentioned technical defects.

[0005] To address the aforementioned technical problems, this invention provides a method for real-time determination of coal and gangue in the horizontal section of coalbed methane, comprising: Step 100: Lower the drilling tool for the horizontal section and obtain the azimuth gamma data of the horizontal section of the coalbed methane. Step 200: Generate an azimuth gamma curve based on the azimuth gamma data and the corresponding well depth data. Step 300: Observe the inflection point of the azimuth gamma curve to predict the encounter with coal and gangue. Step 400: Observe the torque and drilling time at the wellhead to determine if coal or gangue has been encountered. Step 500: Determine that the drilling trajectory is within the horizontal section of the coalbed methane, adjust the drilling trajectory, and continue drilling; Step 600, repeat steps 300-500.

[0006] According to the real-time coal gangue determination method for horizontal sections of coalbed methane, the horizontal section drilling tool consists of a drill bit, a single-bend screw, a short section, a non-magnetic drill collar, and a drill rod connected in sequence; The non-magnetic drill collar is equipped with an azimuth gamma detection tool for acquiring azimuth gamma data.

[0007] According to the real-time determination method of coal gangue in the horizontal section of coalbed methane, the horizontal section drilling tool drills through the target coal seam in the horizontal section of coalbed methane, and the target coal seam is mixed with coal gangue. Above the target coal seam is the upper interface of the target coal seam, and the top layer of the upper interface of the target coal seam is the roof. Below the target coal seam is the target coal seam lower interface, and the bottom layer of the target coal seam lower interface is the bottom plate.

[0008] According to the real-time determination method for coal and gangue in the horizontal section of coalbed methane, step 300 involves observing the inflection point of the azimuth gamma curve and predicting the encounter with coal and gangue, including: Observe the inflection point of the azimuth gamma curve. If the inflection point of the azimuth gamma curve is 1-2m away from the upper or lower interface of the target coal seam, it is predicted that the drilling will encounter coal gangue. At the same time, observe the changes in torque and drilling time at the wellhead.

[0009] According to the real-time determination method for coal and gangue in the horizontal section of coalbed methane, step 400 involves observing the torque and drilling time at the wellhead to determine the encountered coal and gangue, including: If the torque and drilling time are observed at the wellhead, and the torque increases and the drilling time is lengthened, then the drilling footage is adjusted to increase by 2-8m to make the torque and drilling time values ​​normal, and the drilling fluid circulation is normal, then it is determined that coal and gangue have been encountered.

[0010] According to the real-time determination method for coal and gangue in the horizontal section of coalbed methane, step 500, determining that the drilling trajectory is located within the horizontal section of coalbed methane, means: If, during the drilling process, the torque at the wellhead increases and the drilling time lengthens, and the inflection point of the azimuth gamma curve is 2-3 meters away from the upper or lower interface of the target coal seam, it is predicted that coal gangue has been encountered, and the drilling trajectory is determined to be within the horizontal section of the coalbed methane.

[0011] Real-time determination methods for coal gangue in horizontal sections of coalbed methane also include: If it is determined that the drilling trajectory is not within the horizontal section of the coalbed methane, reduce the wellhead rotation speed and perform short tripping operations to maintain wellbore stability.

[0012] According to the real-time determination method for coal and gangue in the horizontal section of coalbed methane, the indication that the drilling trajectory is not within the horizontal section of coalbed methane is: the drill bit of the drilling tool in the horizontal section drills out of the target coal seam. The method for determining that the drilling trajectory is not within the horizontal section of the coalbed methane is as follows: If the upper gamma value of the azimuth gamma curve increases first with increasing well depth, and the lower gamma value increases subsequently, and then the upper and lower gamma values ​​coincide and are higher than the average gamma value, it indicates that the drill bit of the horizontal drilling tool is drilling out from the roof, and thus it indicates that the drilling trajectory is not within the horizontal section of the coalbed methane. If the lower gamma value of the azimuth gamma curve increases first with increasing well depth, followed by an increase in the upper gamma value, and then the upper and lower gamma values ​​coincide, it indicates that the drill bit of the horizontal drilling tool has exited from the bottom plate, and thus indicates that the drilling trajectory is not within the horizontal section of the coalbed methane.

[0013] This invention proposes a method for real-time determination of coal and gangue in the horizontal section of coalbed methane. The method involves drilling through the target coal seam using a horizontal drilling tool, and using an azimuth gamma detection tool inside the horizontal drilling tool to detect whether coal and gangue have been encountered in real time. Once coal and gangue have been encountered, the drilling parameters are adjusted in a timely manner to reduce the degree of downhole collapse and ensure safe drilling in the horizontal section.

[0014] To make the above description of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for real-time determination of coal and gangue in the horizontal section of coalbed methane.

[0016] Figure 2 This is a schematic diagram of a horizontal drilling tool traversing and drilling within the target coal seam.

[0017] Explanation of reference numerals in the attached figures: 10. Horizontal drilling tools; 11. Drill bit; 20. Target coal seam; 30. Coal gangue; 41. Upper interface of the target coal seam; 42. Lower interface of the target coal seam; 51. Top plate; 52. Bottom plate. Detailed Implementation

[0018] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0019] It should be noted that, in this invention, the upper, lower, left, and right in the figure are regarded as the upper, lower, left, and right of the coalbed methane horizontal section coal gangue real-time determination method described in this specification.

[0020] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0021] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0022] This embodiment relates to a method for real-time determination of coal and gangue in the horizontal section of coalbed methane. Please refer to [link / reference needed]. Figure 1 ,include: Step 100: Lower the horizontal drilling tool 10 to obtain the azimuth gamma data of the horizontal section of the coalbed methane.

[0023] The horizontal drilling tool 10 consists of a drill bit 11, a single-bend screw, a short section, a non-magnetic drill collar, and a drill pipe connected in sequence. The non-magnetic drill collar is equipped with an azimuth gamma detection tool for acquiring azimuth gamma data.

[0024] In some embodiments, the short section may be a directional joint.

[0025] Azimuth gamma detection tools measure the radioactivity released during the decay of naturally occurring radioactive nuclei in coal seams. The gamma energy level width can be captured by a scintillation counter to indicate whether the currently drilled well is located in a coal seam.

[0026] Azimuth gamma detection tools open a window in a specific direction and block gamma measurements from other locations. Azimuth gamma probes can be used to measure gamma values ​​at the upper and lower interfaces of coal seams, accurately identify the upper and lower boundary positions of coal seams, and effectively guide the construction of horizontal wells.

[0027] Determination of the upper and lower interfaces of the coal seam - (1) The upper and lower gamma value curves show that when the drill bit drills out of the coal seam from the roof, the upper gamma value increases first because the upper test area is closer to the roof. Then the lower gamma value increases until their values ​​are basically the same and much higher than the average gamma value of the coal seam, indicating that the coal seam has been drilled out. (2) When the drill bit drills out of the coal seam from the bottom, the lower gamma value increases first, and then the upper gamma value increases until their values ​​are basically the same. This means that the drilled well has entered the bottom of the coal seam.

[0028] Please see Figure 2 The horizontal drilling tool 10 drills through the target coal seam 20 in the coalbed methane horizontal section. The target coal seam 20 contains interbedded coal gangue 30. Coal gangue 30 consists of other rock strata (blocks) interbedded within the coal seam, mostly argillaceous rock, claystone, kaolinite claystone, and carbonaceous mudstone. Coal gangue 30 often occurs in layered, quasi-layered, or lenticular shapes, increasing the ash content of the coal and reducing its quality. The presence of coal gangue 30 complicates the coal seam structure; thicker and more argillaceous coal gangue 30 may be misidentified by geologists as roof and floor, making horizontal drilling difficult.

[0029] Please continue reading. Figure 2 Above the target coal seam 20 is the upper interface 41 of the target coal seam, and the top layer of the upper interface 41 of the target coal seam is the roof 51; below the target coal seam 20 is the lower interface 42 of the target coal seam, and the bottom layer of the lower interface 42 of the target coal seam is the bottom 52.

[0030] Figure 2 The hollow arrow in the image indicates the drilling direction for the horizontal section of the coalbed methane.

[0031] In some embodiments, the coalbed methane horizontal section is in accordance with Figure 2 Drilling is carried out in the direction shown, wherein the thickness of the target coal seam 20 is 5-6m; the distance between the designed horizontal section of the wellbore trajectory and the upper interface 41 or lower interface 42 of the target coal seam is 2.5-3m; the thickness of the upper interface 41 or lower interface 42 of the target coal seam is 0.8-1m; the target coal seam 20, i.e., pure coal, is located between the upper interface 41 and the lower interface 42 of the target coal seam, and coal gangue 30 is interbedded in the pure coal; in comparison, the pure coal is softer, while the coal gangue 30, the roof 51, and the floor 52 are harder.

[0032] Step 200: Generate an azimuth gamma curve based on the azimuth gamma data and the corresponding well depth data.

[0033] The measurement data from the azimuth gamma detection tool is transmitted to the ground via a non-magnetic drill collar. The ground data processing system combines the azimuth gamma data with the corresponding well depth data to generate an azimuth gamma curve, which guides the guidance engineer to distinguish the lithological characteristics of the upper and lower interfaces (the upper interface 41 and the lower interface 42 of the target coal seam) and determine the position of the horizontal drilling tool 10 within the target coal seam 20.

[0034] Azimuth gamma curves can display upper gamma values, lower gamma values, and average gamma values.

[0035] During the drilling of the horizontal section of the coalbed methane, the drill bit 11 travels within the target coal seam 20. The gamma probe behind the drill bit 11 transmits and receives signals in real time. The surface data processing system calculates the distance between the drilled borehole and the upper and lower interfaces (the upper interface 41 and the lower interface 42 of the target coal seam) to prevent the borehole from drilling out of the target coal seam 20. The calculation process and principle are existing technologies and will not be elaborated here. Furthermore, the surface data processing system can clearly see the spatial distance between the upper and lower interfaces (the upper interface 41 and the lower interface 42 of the target coal seam).

[0036] Step 300: Observe the inflection point of the azimuth gamma curve and predict the encounter of coal and gangue 30, including: Observe the inflection point of the azimuth gamma curve. If the inflection point of the azimuth gamma curve is 1-2m away from the upper interface 41 or the lower interface 42 of the target coal seam, it is predicted that the drilling will encounter coal gangue 30. At the same time, observe the changes in torque and drilling time at the wellhead.

[0037] For example, if the upper interface 41 of the target coal seam is 3710 and the lower interface 42 of the target coal seam is 3740, then the areas near the upper interface 41 of the target coal seam are 3711 and 3712, and the areas near the lower interface 42 of the target coal seam are 3739 and 3738. If the inflection point of the azimuth gamma curve falls into 3711, 3712, 3711, 3712, it indicates that coal gangue 30 may have been encountered.

[0038] The inflection point of the azimuth gamma curve is a conventional concept in this field. To explain it simply, for example, if the gamma data of the azimuth gamma curve is between 80 and 90, and the gamma data suddenly changes to 97, then that data point is the inflection point.

[0039] Step 400: Observe the torque and drilling time at the wellhead to determine if coal or gangue 30 has been encountered, including: If the torque and drilling time are observed at the wellhead, and the torque increases and the drilling time is lengthened, then the drilling footage is adjusted to increase by 2-8m to make the torque and drilling time values ​​normal, and the drilling fluid circulation is normal. Then it is determined that coal gangue 30 has been encountered.

[0040] Because the coal gangue 30 is relatively hard, drilling into it will lead to increased torque and longer drilling time. Moreover, the gamma data displayed by the ground data processing system is significantly abnormal compared with the existing data. Therefore, it can be determined that the drilling encountered coal gangue 30, rather than the upper interface 41 and lower interface 42 of the target coal seam.

[0041] To further confirm the encounter with coal gangue 30, in this embodiment, after observing an increase in torque and a longer drilling time, the drilling footage can be increased by 2-8m to make the torque and drilling time values ​​normal, and the drilling fluid circulation normal, thus confirming that coal gangue 30 has been encountered.

[0042] Step 500: Determine that the drilling trajectory is within the horizontal section of the coalbed methane, adjust the drilling trajectory, and continue drilling.

[0043] Since the coal gangue 30 is interspersed within the target coal seam 20, when it is determined that the drilling has encountered the coal gangue 30, it can also be determined that the current drilling trajectory is located in the horizontal section of the coalbed methane. At this time, the wellbore trajectory is slightly adjusted to ensure that the drilling wall is smooth and drilling continues in the horizontal section.

[0044] In addition, if the torque at the wellhead increases and the drilling time is extended during the drilling process of the horizontal section drilling tool, and at the same time, the inflection point of the azimuth gamma curve is 2-3m away from the upper or lower interface of the target coal seam, it is predicted that coal gangue has been encountered, and the drilling trajectory is determined to be within the horizontal section of the coalbed methane. At this time, the wellbore is still traveling within 20 of the target coal seam.

[0045] Step 600, repeat steps 300-500.

[0046] In some embodiments, the real-time determination method for coal gangue in the horizontal section of coalbed methane further includes: If it is determined that the drilling trajectory is not within the horizontal section of the coalbed methane, reduce the wellhead rotation speed (50-55 rpm) and perform short tripping operations to maintain wellbore stability. Observe the drilling fluid circulation at the wellhead and the wellbore rock falling off, adjust the drilling fluid properties in a timely manner, reduce the degree of downhole collapse, and ensure safe drilling in the horizontal section.

[0047] The characteristic of a drilling trajectory not being within the horizontal section of the coalbed methane is that the drill bit of the drilling tool in the horizontal section drills out of the target coal seam.

[0048] Specifically, the method for determining that the drilling trajectory is not within the horizontal section of the coalbed methane formation is as follows: (1) If the upper gamma value of the azimuth gamma curve increases first with the increase of well depth, and the lower gamma value increases subsequently, and then the upper gamma value and the lower gamma value coincide and are (far) higher than the average gamma value, it indicates that the drill bit of the drilling tool in the horizontal section drills out from the top plate, and further indicates that the drilling trajectory is not in the horizontal section of the coalbed methane.

[0049] (2) If the lower gamma value of the azimuth gamma curve increases first with the increase of well depth, and the upper gamma value increases subsequently, and then the upper gamma value and the lower gamma value coincide, it indicates that the drill bit of the drilling tool in the horizontal section drills out from the bottom plate, and further indicates that the drilling trajectory is not in the horizontal section of the coalbed methane.

[0050] In some embodiments, the real-time determination method for coal gangue in the horizontal section of coalbed methane includes: Step 1: Analyze the block design to understand the physical properties, burial depth, thickness, regional orientation, and drilling speed of the deep coal seam in the block; analyze the properties of the upper and lower interfaces of the deep coal seam in the block; and lay the foundation for improving the detection rate of deep coal gangue and safe drilling.

[0051] Step 2: Analyze the drilling engineering design to understand the well structure and the technical difficulties of drilling and completion; Horizontal section drilling tool structure: Φ215.9mm PDC drill bit + φ165mm 0.25° single-bend screw + φ165mm short section + 165mm non-magnetic drill collar (gamma detection tool) + φ127mm drill pipe.

[0052] Step 3: During the drilling process, the instrument measures gamma data at the bottom of the well and at a specific azimuth; the data is transmitted to the ground receiving system; the ground system receives the signal and sends it to the computer.

[0053] Step 4: Convert the data measured by the instrument into curves; determine the position of the drilling trajectory in the deep coal seam based on the curves converted from the azimuth gamma data; and simultaneously observe the curves and data inflection points of the ground instruments in real time.

[0054] Step 5: When the curve inflection point is far from the existing deep coal seam upper and lower interface (1-2m), it is predicted that the drilling may have encountered coal gangue inclusions; at the same time, observe the changes in torque and drilling time at the wellhead.

[0055] Step Six: When the wellhead torque increases and the drilling time increases, the wellhead footage increases by 2-8m, and the torque and drilling time return to normal.

[0056] The drilling fluid circulation was normal; it was determined that the drilling encountered coal gangue.

[0057] Step 7: Determine that the current drilling trajectory is still within deep coal seams; make slight adjustments to the wellbore trajectory to ensure a smooth wellbore wall; continue drilling in the horizontal section.

[0058] Step 8: As the wellhead torque increases during drilling, the drilling time rises; observe the curve changes of the downhole carbon nanotube.

[0059] When the curve data of the gamma carbon nanotube is far from the upper and lower interfaces of the deep coal seam (2-3m), it is predicted that the drilling has encountered coal gangue, and the wellbore is still traveling in the coal seam.

[0060] Step 9: When it is determined that the current drilling trajectory is not in the deep coal seam and the wellbore trajectory needs to be adjusted in time, reduce the wellhead rotation speed (50-55 rpm) and perform short tripping operations to maintain wellbore stability.

[0061] Step 10: Observe the drilling fluid circulation at the wellhead and the falling debris on the well wall; adjust the drilling fluid properties in a timely manner; reduce the degree of downhole collapse and ensure safe drilling in the horizontal section.

[0062] Steps five through ten allow for timely understanding of the geological properties of the coal seam encountered by the drill bit, ensuring a higher probability of drilling into the coal seam.

[0063] This embodiment constructs a novel system and method for improving the detection rate of coal gangue inclusions in horizontal sections of coal seams and enhancing safe drilling. It fills the current gaps in related technologies, obtains a real-time method for determining coal gangue in horizontal sections of deep coal seams, reduces the risk of safe drilling of coal gangue in horizontal wells of deep coal seams, reduces the complexity of drilling in horizontal sections of deep coal seams, and provides theoretical support for on-site construction.

[0064] The real-time coalbed methane horizontal section coal gangue determination method provided in this embodiment was applied to well QS-L1. At a well depth of 637.00m, the upper gamma value was greater than the lower gamma value, and both increased to near the gamma value of mudstone. With the mechanical parameters unchanged, the drilling time was significantly greater than the drilling time of the target coal seam 20 by 1-2 min / m, and the footage slowed down (it was estimated that drill bit 11 was about to enter the top of the coal seam). At 643.00m, the upper and lower gamma curves converged, which meant that it had entered the top of the coal seam. At 763-769m, the upper and lower gamma curves diverged and converged, which meant that drill bit 11 encountered coal gangue 30. At this time, the drilling parameters were adjusted in time to prevent wellbore collapse.

[0065] At this point, the tool face control trajectory descends to an angle less than the formation dip angle, making it possible to return to the coal seam as quickly as possible. When the well depth reaches 650.00m, the upper and lower gamma rays converge, indicating that the drill bit has now returned to the coal seam. Subsequent observation of the rock cuttings and gas logging data returned to the surface, combined with comparison with existing geological data, also confirmed that the drill bit did indeed emerge from the top of the coal seam.

[0066] During the third-stage construction of horizontal wells for coalbed methane, the large undulations in the trajectory make it easier for cuttings to accumulate and form a bed of cuttings. It is advisable to perform short-run operations every 100 meters of drilling to ensure the sand-carrying capacity of the drilling fluid, circulate it multiple times to eliminate the cuttings bed, and minimize friction when lowering the drill string with the pump shut off. In horizontal well construction, in addition to using azimuth gamma rays, a comprehensive judgment based on logging data and well logging information can better correct and control the actual drilling trajectory to guide the field. During the build-up section, it is necessary to draw a multi-well landing comparison map and use gamma rays and sand samples to identify marker layers and target coal seams. After a smooth landing, the key construction phase begins in the horizontal section. Trajectory control in the horizontal section must first prevent downhole accidents such as drill bit burial or stuck drill bits, and it must also achieve the specified drilling success rate and horizontal section length. Based on the coal seam and roof and floor properties of adjacent drilled wells and logging data, combined with the coal seam floor contour map, the formation conditions of subsequent well sections are predicted, including the coal seam strike trend, whether there will be large dip angles in some areas, and the characteristics of coal gangue and coal seam thickness.

[0067] by Figure 2 For example, a horizontal well in a deep coal seam is drilled forward as shown in the figure. The thickness of the deep coal seam is 5-6m. The distance between the designed horizontal section of the wellbore trajectory and the upper and lower interfaces is 2.5-3m. The thickness of the upper and lower interfaces is 0.8-1m. The area between the upper and lower coal seams is pure coal, with some coal gangue interspersed between the pure coal. In comparison, the pure coal is softer, while the coal gangue and the caprock at the upper and lower interfaces are harder.

[0068] During the drilling of deep coal horizontal wells, the drill bit travels within the coal seam. A gamma probe behind the drill bit transmits and receives signals in real time, calculating the distance between the drilled wellbore and the upper and lower interfaces. This prevents the wellbore from extending beyond the deep coal seam. Simultaneously, the data curves generated on the surface clearly show the spatial distance between the upper and lower interfaces.

[0069] When the drill bit encounters coal gangue interspersed among pure coal, the torque increases and the drilling time increases; the gamma data of the coal seam measured on the ground is significantly abnormal compared with the existing data, and it is preliminarily determined that the drill bit encountered coal gangue blocks; it is not the upper and lower interface of deep coal.

[0070] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A method for real-time determination of coal and gangue in horizontal sections of coalbed methane, characterized in that, include: Step 100: Lower the drilling tool for the horizontal section and obtain the azimuth gamma data of the horizontal section of the coalbed methane. Step 200: Generate an azimuth gamma curve based on the azimuth gamma data and the corresponding well depth data. Step 300: Observe the inflection point of the azimuth gamma curve to predict the encounter with coal and gangue. Step 400: Observe the torque and drilling time at the wellhead to determine if coal or gangue has been encountered. Step 500: Determine that the drilling trajectory is within the horizontal section of the coalbed methane, adjust the drilling trajectory, and continue drilling; Step 600, repeat steps 300-500.

2. The method for real-time determination of coal and gangue in the horizontal section of coalbed methane according to claim 1, characterized in that, The horizontal section drilling tool consists of a drill bit, a single-bend screw, a short section, a non-magnetic drill collar, and a drill pipe connected in sequence; The non-magnetic drill collar is equipped with an azimuth gamma detection tool for acquiring azimuth gamma data.

3. The method for real-time determination of coal and gangue in the horizontal section of coalbed methane according to claim 2, characterized in that, The horizontal drilling tool drills through the target coal seam in the horizontal section of the coalbed methane, and the target coal seam contains coal gangue; Above the target coal seam is the upper interface of the target coal seam, and the top layer of the upper interface of the target coal seam is the roof. Below the target coal seam is the target coal seam lower interface, and the bottom layer of the target coal seam lower interface is the bottom plate.

4. The method for real-time determination of coal and gangue in the horizontal section of coalbed methane according to claim 3, characterized in that, Step 300: Observe the inflection point of the azimuth gamma curve to predict the encounter with coal and gangue, including: Observe the inflection point of the azimuth gamma curve. If the inflection point of the azimuth gamma curve is 1-2m away from the upper or lower interface of the target coal seam, it is predicted that the drilling will encounter coal gangue. At the same time, observe the changes in torque and drilling time at the wellhead.

5. The method for real-time determination of coal and gangue in the horizontal section of coalbed methane according to claim 1 or 4, characterized in that, Step 400 involves observing the torque and drilling time at the wellhead to determine if coal or gangue has been encountered, including: If the torque and drilling time are observed at the wellhead, and the torque increases and the drilling time is lengthened, then the drilling footage is adjusted to increase by 2-8m to make the torque and drilling time values ​​normal, and the drilling fluid circulation is normal, then it is determined that coal and gangue have been encountered.

6. The method for real-time determination of coal and gangue in the horizontal section of coalbed methane according to claim 3 or 4, characterized in that, Step 500, determining that the drilling trajectory is located within the horizontal section of the coalbed methane, means: If, during the drilling process, the torque at the wellhead increases and the drilling time lengthens, and the inflection point of the azimuth gamma curve is 2-3 meters away from the upper or lower interface of the target coal seam, it is predicted that coal gangue has been encountered, and the drilling trajectory is determined to be within the horizontal section of the coalbed methane.

7. The method for real-time determination of coal and gangue in the horizontal section of coalbed methane according to claim 3, characterized in that, Also includes: If it is determined that the drilling trajectory is not within the horizontal section of the coalbed methane, reduce the wellhead rotation speed and perform short tripping operations to maintain wellbore stability.

8. The method for real-time determination of coal and gangue in the horizontal section of coalbed methane according to claim 7, characterized in that, The indication that the drilling trajectory is not within the horizontal section of the coalbed methane is that the drill bit of the drilling tool in the horizontal section drills out of the target coal seam; The method for determining that the drilling trajectory is not within the horizontal section of the coalbed methane is as follows: If the upper gamma value of the azimuth gamma curve increases first with increasing well depth, and the lower gamma value increases subsequently, and then the upper and lower gamma values ​​coincide and are higher than the average gamma value, it indicates that the drill bit of the horizontal drilling tool is drilling out from the roof, and thus it indicates that the drilling trajectory is not within the horizontal section of the coalbed methane. If the lower gamma value of the azimuth gamma curve increases first with increasing well depth, followed by an increase in the upper gamma value, and then the upper and lower gamma values ​​coincide, it indicates that the drill bit of the horizontal drilling tool has exited from the bottom plate, and thus indicates that the drilling trajectory is not within the horizontal section of the coalbed methane.

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