A method for alarming when a roof and floor are drilled in coal seam air drilling

Abstract

The present application relates to a kind of coal seam air drilling in drilling roof and floor alarm method, belong to coal mine directional drilling field.The present application includes the following steps: the recess surface of one place in the front part of drill pipe at the front end of screw drill rod column is plated with insulating coating, two non-contact metal sheets on the insulating coating are fixed as electrode for measuring resistance value;Power supply and signal transmitting device are fixed in drill pipe;Positive pole of power supply in drill pipe is connected with positive pole metal sheet on insulating coating by wire, negative pole is connected with negative pole metal sheet on insulating coating by wire, current meter is connected in series in wire;When air drilling, air circulation speed is fast, cuttings are accumulated in the recess of drill pipe to form current path, current meter can measure current after drill pipe internal power supply provides voltage, and resistance value R between two electrodes is calculated according to current;If resistance value R mutates, coal seam and roof and floor interface are identified and timely alarm.

Description

Technical Field

[0001] This invention relates to an alarm method for encountering the roof and floor during air drilling in coal seams, belonging to the field of directional drilling in coal mines. Background Technology

[0002] Before coal mining, it is usually necessary to extract the coalbed methane (CBM) contained in the coal seam using surface or underground drilling. This provides clean energy and prevents underground gas explosions. To maximize CBM extraction efficiency and reduce production risks, high-pressure air is used as a circulating medium in air drilling of coal seams. This medium cools the drill bit, protects the wellbore, and carries rock cuttings to the wellhead. Air drilling is efficient, low-cost, and safe within the borehole. However, due to its high drilling speed, it is easy to drill through or lose the coal seam, causing significant losses to the drilling operation. Therefore, timely identification of the interface between the coal seam and the roof and floor is crucial for keeping the drill bit within the coal seam and improving CBM extraction efficiency. Currently, in the field of directional drilling in coal mines, gamma and resistivity meters are commonly used to identify the resistivity of the coal seam and surrounding rock to determine the interface. However, the measurement position is several meters or even tens of meters away from the drill bit, and the measured data is delayed, failing to identify the roof or floor encountered in real time, affecting drilling efficiency and incurring high costs. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides an alarm method for encountering the roof and floor during coal seam air drilling. This invention can transmit data in real time, and it can also save costs and improve the coal seam drilling rate and work efficiency.

[0004] To achieve the above objectives, the technical solution provided by this invention is: a method for alarming when encountering the roof and floor during air drilling in coal seams, specifically including the following steps:

[0005] S101: The auger drill string consists of two or more drill rods. An insulating coating is plated on the surface of one of the grooves at the front of the drill rod at the front end of the auger drill string. Two non-contacting metal plates are fixed on the insulating coating as electrodes for measuring resistance.

[0006] S102: A power supply and signal transmitting device are fixed inside the drill pipe at the front end of the auger drill string, and the power supply voltage is constant at U;

[0007] S103: The power source, positive electrode metal plate, negative electrode metal plate, ammeter, and rock debris between the positive and negative electrode metal plates form a current path;

[0008] S104: After the current path is formed, the resistance value R = U / I between the two electrodes is calculated based on the constant voltage U of the power supply and the current I measured by the ammeter.

[0009] S105: The measured resistance value R of rock cuttings between the two electrodes is transmitted to the wellhead via a signal transmitting device. If the measured resistance value R changes abruptly, the interface between the coal seam and the roof and floor is identified and an alarm is triggered in time.

[0010] In step S101, the auger drill string consists of two or more drill rods. An insulating coating is plated on the surface of a groove at the front of the foremost drill rod of the auger drill string. Two non-contacting metal plates are fixed on the insulating coating as electrodes for measuring the resistance value; specifically:

[0011] The grooves in the drill pipe experience less friction from the well wall. By plating an insulating layer on the grooves, the drill pipe is less prone to wear and failure. After fixing the metal sheet onto the insulating coating, the insulating coating separates the drill pipe from the metal sheet. The two mutually insulated metal sheets form the two poles for measuring the resistance value.

[0012] In step S103, a current path is formed between the power source, the positive electrode metal plate, the negative electrode metal plate, the ammeter, and the rock debris between the positive and negative electrode metal plates; specifically:

[0013] The circulating medium is air, so the two metal plates that make up the two poles are disconnected. During the drilling process, after the rock cuttings accumulate and compact in the groove of the drill pipe, the power supply, wires, ammeter, positive metal plate, rock cuttings and negative metal plate form a current path.

[0014] In step S105, the measured resistance value R of the rock cuttings between the two electrodes is transmitted to the wellhead via a signal transmitting device. If the measured resistance value R changes abruptly, the interface between the coal seam and the roof and floor is identified and an alarm is triggered promptly. Specifically:

[0015] The drill bit is mounted at the very front of the drill rod at the very front of the auger drill string. A signal transmitter transmits the resistance value R of the rock cuttings generated by the drill bit in the drilling strata between the two electrodes to the wellhead. If the drill bit enters the roof or floor, the measured resistance value R will change abruptly, triggering an alarm and identifying the interface between the coal seam and the roof or floor. Then, the borehole trajectory is adjusted to keep the drill bit drilling horizontally in the coal seam. If the measured resistance value R does not change abruptly, the drill bit continues to drill.

[0016] As can be seen from the above technical solution, the present invention provides an alarm method for encountering the roof and floor during air drilling in coal seams. This method involves coating an insulating layer onto the surface of a groove at the front of the drill rod at the very front of the auger string, fixing two non-contacting metal plates on the insulating layer, and placing a power source inside the drill rod. This creates a current path during air drilling in the coal seam, connecting the power source, ammeter, positive electrode metal plate, rock cuttings, and negative electrode metal plate. The resistance data of the rock cuttings between the two electrodes is measured and transmitted to the wellhead. If the resistance value R of the rock cuttings between the two electrodes changes abruptly, the interface between the coal seam and the roof and floor is identified, and an alarm is triggered promptly. Compared with existing technologies such as gamma meters and resistivity meters, this invention offers real-time performance, improves the coal seam encounter rate and work efficiency, and is cost-effective. Attached Figure Description

[0017] Figure 1 A flowchart of a method for alarming when encountering the roof and floor during air drilling in coal seams;

[0018] Figure 2 A schematic diagram illustrating the alarm triggered when encountering the roof and floor during air drilling in coal seams;

[0019] Figure 3 A schematic diagram of the power supply and ammeter inside the drill pipe, as well as the insulation layer and metal sheet of the groove.

[0020] Figure 2 In the middle: 1. The front part of the drill rod at the very front of the auger drill string; 2. Air; 3. Drill rod.

[0021] Figure 3 In the middle: 1. The front part of the drill rod at the very front end of the auger drill string; 2. Ammeter; 3. Positive electrode metal plate; 4. Insulating coating; 5. Wire; 6. Power supply; 7. Negative electrode metal plate. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0023] The technical solution provided by this invention is a method for alarming when encountering the roof and floor during air drilling in coal seams, specifically including the following steps:

[0024] S101: The auger drill string consists of two or more drill rods. An insulating coating is plated on the surface of one of the grooves at the front of the drill rod at the front end of the auger drill string. Two non-contacting metal plates are fixed on the insulating coating as electrodes for measuring resistance.

[0025] Specifically, the groove of the drill pipe experiences less friction from the well wall. An insulating layer is plated in the groove of the drill pipe to prevent it from being worn and failing. After the metal sheet is fixed on the insulating coating, the insulating coating separates the drill pipe from the metal sheet. The two mutually insulated metal sheets form the two poles for measuring the resistance value.

[0026] S102: A power supply and signal transmitting device are fixed inside the drill pipe at the front end of the auger drill string, and the power supply voltage is constant at U;

[0027] S103: The power source, positive electrode metal plate, negative electrode metal plate, ammeter, and rock debris between the positive and negative electrode metal plates form a current path;

[0028] Specifically, the circulating medium is air, so the two metal plates that make up the two poles are disconnected. During the drilling process, after the rock cuttings accumulate and compact in the groove of the drill rod, the power supply, wires, ammeter, positive metal plate, rock cuttings and negative metal plate form a current path.

[0029] S104: After the current path is formed, the resistance value R = U / I between the two electrodes is calculated based on the constant voltage U of the power supply and the current I measured by the ammeter.

[0030] S105: The measured resistance value R of rock cuttings between the two electrodes is transmitted to the wellhead via a signal transmitting device. If the measured resistance value R changes abruptly, the interface between the coal seam and the roof and floor is identified and an alarm is triggered in time.

[0031] Specifically, the drill bit is installed at the very front of the drill rod at the very front of the auger drill string. The resistance value R of the rock cuttings generated by the drill bit in the drilling strata between the two electrodes is transmitted to the wellhead through a signal transmitting device. If the drill bit drills into the roof or floor, the measured resistance value R will change abruptly, triggering an alarm and identifying the interface between the coal seam and the roof or floor. Then, the borehole trajectory is adjusted to keep the drill bit drilling horizontally in the coal seam. If the measured resistance value R does not change abruptly, the drill bit continues to drill.

[0032] Example 1: Reference Figure 2 and Figure 3 , Figure 2 In the middle section, the strata have a horizontal layered structure. The front part 1 of the auger drill string drills along the coal seam from the roadway, and the drilling circulating medium is air 2. The specific structure of the power supply, ammeter, and the insulation layer and metal plates of the groove inside the drill pipe is as follows: Figure 3 As shown, Figure 3 In the process, an insulating layer 4 is plated in the groove at the front part 1 of the auger drill string. The insulating layer fixes the positive electrode metal plate 3 and the negative electrode metal plate 7. The positive electrode metal plate 3 is connected to the positive terminal of the power supply 6 through a wire 5, and the negative terminal of the power supply 6 is connected to the negative electrode metal plate 7 through a wire 5. The ammeter 2 is connected in series with the wire 5. When drilling in the coal seam, the power supply generates a constant voltage U. After the rock cuttings accumulate in the groove at the front part 1 of the auger drill string to form a current path, the ammeter measures the current data I and calculates the rock cutting resistance value R = U / I. This resistance data is transmitted to the wellhead through a wired cable or an electromagnetic transmitter. When drilling into the roof or floor, due to the significant change in lithology, the resistance value R of the rock cuttings generated during drilling shows a significant difference between the two electrodes, which promptly alarms the drilling into the roof or floor. The operators adjust the borehole trajectory in time to keep the drill bit drilling horizontally in the coal seam.

Claims

1. A method for alarming when encountering the roof and floor during air drilling in coal seams, characterized in that... Specifically, the following steps are included: S101: The auger drill string consists of two or more drill rods. An insulating coating is plated on the surface of one of the grooves at the front of the drill rod at the front end of the auger drill string. Two non-contacting metal plates are fixed on the insulating coating as electrodes for measuring resistance. The groove of the drill pipe experiences less friction from the well wall. By plating an insulating layer on the groove of the drill pipe, it is less likely to be worn and fail. After fixing the metal sheet on the insulating coating, the insulating coating separates the drill pipe from the metal sheet. The two mutually insulated metal sheets form the two poles for measuring the resistance value. S102: A power supply and signal transmitting device are fixed inside the drill pipe at the front end of the auger drill string, and the power supply voltage is constant at U; S103: The power source, positive electrode metal plate, negative electrode metal plate, ammeter, and rock debris between the positive and negative electrode metal plates form a current path; The circulating medium is air, so the two metal plates that make up the two poles are disconnected. During the drilling process, after the rock cuttings accumulate and compact in the groove of the drill pipe, the power supply, wires, ammeter, positive metal plate, rock cuttings and negative metal plate form a current path. S104: After the current path is formed, the resistance value R between the two electrodes of the rock cuttings is calculated based on the constant voltage U of the power supply and the current I measured by the ammeter. S105: The measured resistance value R of rock cuttings between two electrodes is transmitted to the wellhead through a signal transmitting device. If the measured resistance value R changes abruptly, the interface between the coal seam and the roof and floor is identified and an alarm is triggered in time. The drill bit is mounted at the very front of the drill rod at the very front of the auger drill string. A signal transmitter transmits the resistance value R of the rock cuttings generated by the drill bit in the drilling strata between the two electrodes to the wellhead. If the drill bit enters the roof or floor, the measured resistance value R will change abruptly, triggering an alarm and identifying the interface between the coal seam and the roof or floor. Then, the borehole trajectory is adjusted to keep the drill bit drilling horizontally in the coal seam. If the measured resistance value R does not change abruptly, the drill bit continues to drill.

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