A method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells

Abstract

A method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells specifically includes the following steps: (1) Assemble a device for preventing coal powder settlement in the drainage of coalbed methane, which includes a coal powder monitoring system, a coal powder disturbance system, a signal transmitter, an alarm, and a computer remote control system; (2) Lower the coal powder monitoring system and the coal powder disturbance system into the target position in the wellbore together with the sucker rod; (3) Input the critical value of coal powder concentration and disturbance instructions into the computer remote control system; (4) Start the pump for normal drainage of coalbed methane. The coal powder monitoring system monitors the coal powder concentration in the wellbore in real time, and controls the coal powder disturbance system to perform disturbance operations in the wellbore; (5) After the coal powder concentration returns to normal, the coal powder monitoring system enters the normal monitoring state. The present invention can monitor the coal powder concentration in the wellbore in real time and perform disturbance operations on the coal powder, prevent the coal powder from settling and accumulating in the wellbore, reduce the number of workover operations, and achieve the normal drainage of coalbed methane wells.

Description

Technical Field

[0001] The present invention relates to the technical field of coalbed methane extraction, and specifically, to a method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells. Background Art

[0002] Coalbed methane is mainly stored in the coal reservoir in an adsorbed state. When conducting coalbed methane development on the ground, it is necessary to drain the water in the coal seam through the wellbore to reduce the reservoir pressure, so that the coalbed methane desorbs and is produced. Coal itself has the characteristic of low elastic modulus. After the reservoir is fracturing reformed, the coal seam is further fragmented. During drainage, coal powder will gradually migrate to the wellbore. When the drainage intensity is small and it is not enough to carry the coal powder out of the wellbore, the coal powder will accumulate at a certain part in the wellbore. The production of coal powder will reduce the pump efficiency, and in severe cases, it will cause pump jamming and even lead to the fracture of the sucker rod.

[0003] In order to prevent the settlement and accumulation of coal powder in the wellbore, domestic scientific and technological workers have carried out fruitful research. By injecting water into the annulus between the tubing and the casing through the wellhead three-way with a pressure washing pump device, while keeping the dynamic liquid level dropping steadily, the water output in the wellbore is increased, the flow rate of the drainage water in the tubing is increased, and the coal powder deposited in the tubing and the pump barrel is driven to be discharged to the ground, so as to achieve the purpose of reducing the coal powder concentration in the wellbore and extending the pump inspection period. However, this method requires continuous equipment handling to maintain the liquid drainage volume in the wellbore. At the same time, if the injection water volume is small, the amount of returned coal powder is limited and it is easy to cause coal powder blockage. The mechanical coal powder fishing operation uses a tubing-conveyed coal powder fishing pump to go down the well. After contacting the coal powder surface, by lifting and lowering the tubing, the coal powder particles in the casing are continuously sucked into the tubing string serving as the coal powder barrel under the fishing pump and brought to the ground, thus playing the role of fishing coal powder. However, the fishing coal powder operation adopts the method of well killing or venting. Well killing causes water to flow into the coal seam, which may block the channels. Moreover, the fishing coal powder operation requires lifting the drainage equipment out of the bottom of the well, affecting the normal progress of drainage. Using a three-truck movable well washing device, washing one well requires the cooperation of three vehicles, namely a sewage treatment device vehicle, a well washing pump vehicle, and a water tank vehicle. It is not convenient to use and operate, and the construction cost is relatively high. Therefore, it is urgent to develop a method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells, which can not only timely process the settled coal powder in the wellbore, but also reduce costs and enable the normal production of coalbed methane wells. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells. The present invention can monitor and disturb the coal powder in the drainage wellbore in real time, prevent the coal powder from settling and accumulating in the wellbore, reduce the number of workover operations, and realize the normal drainage of coalbed methane wells.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells, specifically including the following steps:

[0007] (1). Assemble a coal powder anti-settlement device for coalbed methane drainage. This coal powder anti-settlement device for coalbed methane drainage includes a coal powder monitoring system, a coal powder disturbance system, a signal transmitter, an alarm, and a computer remote control system. Both the coal powder monitoring system and the coal powder disturbance system are installed on the outer circumference of a certain section of sucker rod. The coal powder monitoring system is located below the coal powder disturbance system. The signal transmitter is installed on the sucker rod of the section closest to the ground. The alarm and the computer remote control system are set in the control room on the ground. The computer remote control system is signal-connected to the signal transmitter and the alarm respectively. The signal transmitter is signal-connected to the coal powder monitoring system and the coal powder disturbance system respectively. The coal powder disturbance system is electrically connected to the ground power supply;

[0008] (2). Lower the coal powder monitoring system and the coal powder disturbance system into the target position in the tubing in the wellbore together with the sucker rod;

[0009] (3). Input the critical value of coal powder concentration and the disturbance instruction into the computer remote control system;

[0010] (4). Start the pump for normal drainage of coalbed methane. Real-time monitor the coal powder concentration in the wellbore through the coal powder monitoring system. If the coal powder concentration is abnormal, control the coal powder disturbance system to perform corresponding disturbance operations in the wellbore to prevent coal powder from settling and accumulating;

[0011] (5). When the coal powder concentration returns to normal, the coal powder disturbance system stops the disturbance operation, and the coal powder monitoring system enters the normal monitoring state.

[0012] The coal powder monitoring system includes a capacitive density sensor. The capacitive density sensor is fixedly connected to a certain section of the sucker rod through a hoop. The signal transmitter is fixedly connected to the middle of the outer side wall of the sucker rod of the section closest to the ground through a hoop. The signal transmitter is signal-connected to the capacitive density sensor.

[0013] The coal powder disturbance system includes a C-type support, a fixed pulley, a disturbance motor, a disturbance gear, a rigid rope and two rope positioning rings. The upper side, the lower side and the outer side of the C-type support are all open. The C-type support is fixedly connected to a fuel-saving rod above the capacitive density sensor through a hoop. The fixed pulley is rotatably installed in the C-type support. The disturbance motor is fixedly installed on the side plate of the C-type support. The power shaft of the disturbance motor is coaxially connected to the central axis of the fixed pulley. The disturbance gear is arranged below the fixed pulley. One end of the rigid rope is fixedly wound around the fixed pulley, and the other end of the rigid rope extends downward from the fixed pulley and is fixedly connected to the disturbance gear. The two rope positioning rings are arranged at intervals up and down and are fixedly connected to a fuel-saving rod between the fixed pulley and the disturbance gear through a hoop. The rigid rope vertically passes through the two rope positioning rings. The disturbance gear is equipped with an electronic positioner. The signal transmitter is respectively connected to the disturbance motor and the electronic positioner signal, and the disturbance motor is electrically connected to the ground power supply.

[0014] The alarm is equipped with a built-in buzzer and three signal indicator lights, which are green, yellow and red respectively. The computer remote control system is connected with the buzzer and the three signal indicator lights respectively.

[0015] The computer remote control system and the signal transmitter are connected, as are the signal transmitter and the capacitive density sensor, the disturbance motor and the electronic positioner through corrosion-resistant signal cables. Each corrosion-resistant signal cable is fixedly connected to the corresponding fuel-saving rod through a number of hoops spaced apart vertically.

[0016] The distance between the two rope positioning rings and the distance between the fixed pulley and the rope positioning ring on the upper side are both 5m. Initially, the disturbance gear is located above the capacitive density sensor and the distance to the capacitive density sensor is less than 0.5m.

[0017] Step (ii) is specifically as follows: after assembling and debugging the coalbed methane drainage and coal dust anti-sedimentation device according to the design requirements, the layer section where coal dust is easily accumulated in the wellbore is obtained based on previous data, the insertion depth of the capacitive density sensor is calculated, and the capacitive density sensor is lowered into the oil pipe in the wellbore together with the oil rod. At the same time, the coal dust disturbance system is also lowered into the oil pipe in the wellbore together with the oil rod. The position of the disturbance gear in the wellbore can be obtained through the electronic positioner until the disturbance gear is lowered into the layer section where coal dust is easily accumulated in the wellbore, and the oil rod is stopped from being lowered, so that the capacitive density sensor is lowered to the calculated depth.

[0018] Step (iii) is specifically as follows: The staff inputs three gradually increasing critical values of pulverized coal concentration into the control software built in the computer remote control system. When the pulverized coal concentration in the shaft is lower than the first critical value of pulverized coal concentration, it is determined that the pulverized coal concentration in the shaft is normal, and the green light on the alarm goes on. When the pulverized coal concentration in the shaft exceeds the first critical value of pulverized coal concentration, it is determined that the pulverized coal concentration in the shaft is abnormal, that is, pulverized coal settles and accumulates in the shaft, the buzzer gives an alarm, and the red light on the alarm goes on. If the entire device fails, the yellow light on the alarm goes on;

[0019] When the pulverized coal concentration in the shaft is abnormal, the control software built in the computer remote control system determines the severity of pulverized coal settlement and accumulation in the shaft according to the three critical values of pulverized coal concentration, and classifies the severity of pulverized coal settlement and accumulation in the shaft into three levels: low, medium, and high. When the pulverized coal concentration in the shaft exceeds the first critical value of pulverized coal concentration and is lower than the second critical value of pulverized coal concentration, it is determined that the severity of settlement and accumulation is low. When the pulverized coal concentration in the shaft exceeds the second critical value of pulverized coal concentration and is lower than the third critical value of pulverized coal concentration, it is determined that the severity of pulverized coal settlement and accumulation in the shaft is medium. When the pulverized coal concentration in the shaft exceeds the third critical value of pulverized coal concentration, it is determined that the severity of pulverized coal settlement and accumulation in the shaft is high;

[0020] At the same time, three different disturbance instructions are respectively input corresponding to the three levels of the severity of pulverized coal settlement and accumulation in the shaft: When the severity of pulverized coal settlement and accumulation in the shaft is low, the corresponding disturbance instruction is to perform a disturbance every 2 hours within 24 hours. When the severity of pulverized coal settlement and accumulation in the shaft is medium, the corresponding disturbance instruction is to perform a disturbance every 1 hour within 24 hours. When the severity of pulverized coal settlement and accumulation in the shaft is high, the corresponding disturbance instruction is to perform a disturbance every 0.5 hour within 24 hours.

[0021] Step (iv) is specifically as follows: After starting the pump, the sucker rod rotates automatically, and the normal production of coalbed methane begins. The capacitive density sensor monitors the pulverized coal concentration in the shaft in real time and transmits the pulverized coal concentration information to the computer remote control system. The display interface of the computer remote control system displays the pulverized coal concentration in real time:

[0022] a. The alarm gives an alarm signal:

[0023] During the normal production process, when the buzzer gives an alarm sound and the green light on the alarm jumps to the red light, it is determined that the pulverized coal concentration exceeds the standard, that is, the pulverized coal concentration in the shaft is abnormal;

[0024] b. Determine the severity of pulverized coal settlement and accumulation in the shaft and trigger the computer remote control system to issue corresponding disturbance instructions:

[0025] After the alarm emits an alarm signal, the control software built into the computer remote control system determines the severity of coal powder settlement and accumulation in the wellbore as low, medium, or high. The computer remote control system controls the coal powder disturbance system to perform disturbance operations according to the corresponding disturbance instructions;

[0026] c. The coal powder disturbance system performs disturbance operations in the wellbore:

[0027] Taking the case where the severity of coal powder settlement and accumulation in the wellbore is high as an example, the coal powder disturbance system starts to operate. The disturbance motor drives the fixed pulley to rotate periodically in a reciprocating manner. Then, the reciprocating rotation of the fixed pulley causes the rigid rope to drive the disturbance gear to move up and down in the wellbore reciprocally. At the same time, driven by the self-rotation of the oil rod, the disturbance gear makes a rotational motion in the wellbore, disturbing the coal powder in the wellbore to prevent coal powder aggregation, and then discharging the coal powder out of the wellbore. The up and down movement distance of each disturbance operation of the disturbance gear is 10m, and the disturbance is carried out once every 0.5h, for a total of 48 times within 24h;

[0028] d. Reconfirm the coal powder concentration in the wellbore:

[0029] When the disturbance operation ends, the coal powder in the wellbore is allowed to stand for 2h, and the coal powder concentration in the wellbore is the real concentration. At this time, if the coal powder concentration in the wellbore is lower than the first coal powder concentration critical value, the red light on the alarm automatically turns into a green light, the buzzer stops sounding the alarm, and the coal powder disturbance system stops the disturbance operation. If the coal powder concentration in the wellbore is still abnormal, repeat steps b and c until the coal powder concentration in the wellbore is lower than the first coal powder concentration critical value, that is, the coal powder concentration in the wellbore is in a normal state.

[0030] The present invention has outstanding substantive features and significant progress compared with the prior art. Specifically, the present invention has the following advantages:

[0031] (1) The present invention can realize real-time monitoring of the coal powder concentration at the target position in the wellbore through the capacitive density sensor, enabling the computer remote control system to quickly issue corresponding disturbance instructions. The coal powder disturbance system operates in a timely manner to solve the problem of coal powder aggregation, reduce the number of workover operations, and achieve normal production and drainage of coalbed methane wells;

[0032] (2) The present invention can give different degrees of disturbance operation instructions according to different coal powder concentrations and aggregation degrees in the wellbore, achieving the purpose of discharging the coal powder in the wellbore to the ground.

[0033] In summary, the present invention can monitor and disturb the coal powder in the production wellbore in real time, prevent the coal powder from settling and aggregating in the wellbore, reduce the number of workover operations, and achieve normal production and drainage of coalbed methane wells. Brief Description of the Drawings

[0034] Figure 1 It is a layout structure schematic diagram of the coalbed methane drainage coal powder anti-settlement device of the present invention.

[0035] Figure 2 It is a schematic connection diagram of the signal transmitter of the present invention and a corresponding section of the oil rod.

[0036] Figure 3 It is a schematic connection diagram of the capacitive density sensor of the present invention and a corresponding section of the oil rod.

[0037] Figure 4 It is a schematic connection diagram of the C-shaped support, the fixed pulley and the disturbance motor of the present invention and a corresponding section of the oil rod.

[0038] Figure 5 It is a schematic connection diagram of the rope positioning ring of the present invention and a corresponding section of the oil rod.

[0039] Figure 6 It is Figure 1 The partial enlarged view at position A in Specific embodiments

[0040] The following further illustrates the embodiments of the present invention with reference to the accompanying drawings.

[0041] As Figure 1-6 shown, a method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells specifically includes the following steps:

[0042] (1). Assemble a coal powder anti-settlement device for coalbed methane drainage. This coal powder anti-settlement device for coalbed methane drainage includes a coal powder monitoring system, a coal powder disturbance system, a signal transmitter 1, an alarm 2, and a computer remote control system 3. Both the coal powder monitoring system and the coal powder disturbance system are installed on the outer circumference of a certain section of the oil rod 4. The coal powder monitoring system is located below the coal powder disturbance system. The signal transmitter 1 is installed on the oil rod 4 closest to the ground. The alarm 2 and the computer remote control system 3 are arranged in the control room on the ground. The computer remote control system 3 is respectively signal-connected to the signal transmitter 1 and the alarm 2. The signal transmitter 1 is respectively signal-connected to the coal powder monitoring system and the coal powder disturbance system. The coal powder disturbance system is electrically connected to the ground power supply;

[0043] (2). Lower the coal powder monitoring system and the coal powder disturbance system together with the oil rod 4 to the target position in the inner pipe 18 of the wellbore 16;

[0044] (3). Input the critical value of coal powder concentration and the disturbance instruction into the computer remote control system 3;

[0045] (4). Start the pump to conduct normal coalbed methane drainage. Real-time monitor the coal powder concentration in the wellbore 16 through the coal powder monitoring system. If the coal powder concentration is abnormal, control the coal powder disturbance system to perform corresponding disturbance operations in the wellbore 16 to prevent coal powder from settling and accumulating;

[0046] (V) When the coal powder concentration returns to normal, the coal powder disturbance system stops the disturbance operation in the shaft 16, and the coal powder monitoring system enters the normal monitoring state.

[0047] The coal powder monitoring system includes a capacitive density sensor 5, which is fixedly connected to a certain fuel-saving rod 4 through a hoop 6. The signal transmitter 1 is fixedly connected to the middle of the outer wall of the fuel-saving rod 4 closest to the ground through the hoop 6. The signal transmitter 1 is connected to the capacitive density sensor 5 signal.

[0048] The coal powder disturbance system includes a C-type support 7, a fixed pulley 8, a disturbance motor 9, a disturbance gear 10, a rigid rope 11 and two rope positioning rings 12. The upper side, the lower side and the outer side of the C-type support 7 are all open. The C-type support 7 is fixedly connected to a certain fuel-saving rod 4 above the capacitive density sensor 5 through a hoop 6. The fixed pulley 8 is rotatably installed in the C-type support 7. The disturbance motor 9 is fixedly installed on the side plate of the C-type support 7. The power shaft of the disturbance motor 9 is coaxially connected to the central axis of the fixed pulley 8. The disturbance gear 10 is arranged below the fixed pulley 8. The rigid rope 11 is provided with a plurality of rope positioning rings 12. One end of the rigid rope 11 is fixedly wound on the fixed pulley 8, and the other end of the rigid rope 11 extends downward from the fixed pulley 8 and is fixedly connected to the disturbance gear 10. Two rope positioning rings 12 are arranged at intervals up and down and are fixedly connected to a fuel-saving rod 4 between the fixed pulley 8 and the disturbance gear 10 through a hoop 6. The rigid rope 11 vertically passes through the two rope positioning rings 12. The disturbance gear 10 is equipped with an electronic positioner 17. The signal transmitter 1 is respectively connected to the disturbance motor 9 and the electronic positioner 17 signals, and the disturbance motor 9 is electrically connected to the ground power supply.

[0049] The alarm 2 has a built-in buzzer 13 and is provided with three signal indicator lights 14 , which are respectively a green light, a yellow light and a red light. The computer remote control system 3 is respectively connected to the buzzer 13 and the three signal indicator lights 14 by signals.

[0050] The computer remote control system 3 and the signal transmitter 1, as well as the signal transmitter 1 and the capacitive density sensor 5, the disturbance motor 9 and the electronic positioner 17 are connected via corrosion-resistant signal cables 15, and each corrosion-resistant signal cable 15 is fixedly connected to the corresponding fuel-saving rod 4 via a plurality of hoops 6 spaced apart vertically.

[0051] The distance between the two rope positioning rings 12 and the distance between the fixed pulley 8 and the upper rope positioning ring 12 are both 5 m. Initially, the disturbance gear 10 is located above the capacitive density sensor 5 and the distance from the capacitive density sensor 5 is less than 0.5 m.

[0052] Step (2) is specifically as follows: After assembling and debugging the coalbed methane drainage and coal powder anti-settlement device according to the design requirements, based on past data, determine the section in the wellbore 16 where coal powder is prone to accumulate, calculate the lowering depth of the capacitive density sensor 5, and lower the capacitive density sensor 5 into the tubing 18 in the wellbore 16 together with the sucker rod 4. At the same time, the coal powder disturbance system is also lowered into the tubing 18 in the wellbore 16 together with the sucker rod 4. The position of the disturbance gear 10 in the wellbore 16 can be obtained through the electronic locator 17. Stop lowering the sucker rod 4 until the disturbance gear 10 is lowered into the section in the wellbore 16 where coal powder is prone to accumulate, thereby lowering the capacitive density sensor 5 to the calculated depth.

[0053] Step (3) is specifically as follows: The staff inputs three gradually increasing critical values of coal powder concentration into the control software built in the computer remote control system 3. When the coal powder concentration in the wellbore 16 is lower than the first critical value of coal powder concentration, it is determined that the coal powder concentration in the wellbore 16 is normal, and the green light on the alarm 2 lights up. When the coal powder concentration in the wellbore 16 exceeds the first critical value of coal powder concentration, it is determined that the coal powder concentration in the wellbore 16 is abnormal, that is, coal powder settles and accumulates in the wellbore 16, the buzzer 13 gives an alarm, and the red light on the alarm 2 lights up. If the entire device fails, the yellow light on the alarm 2 lights up;

[0054] When the coal powder concentration in the wellbore 16 is abnormal, the control software built in the computer remote control system 3 determines the severity of coal powder settlement and accumulation in the wellbore 16 based on the three critical values of coal powder concentration, and classifies the severity of coal powder settlement and accumulation in the wellbore 16 into three levels: low, medium, and high. When the coal powder concentration in the wellbore 16 exceeds the first critical value of coal powder concentration and is lower than the second critical value of coal powder concentration, it is determined that the severity of coal powder settlement and accumulation in the wellbore 16 is low. When the coal powder concentration in the wellbore 16 exceeds the second critical value of coal powder concentration and is lower than the third critical value of coal powder concentration, it is determined that the severity of coal powder settlement and accumulation in the wellbore 16 is medium. When the coal powder concentration in the wellbore 16 exceeds the third critical value of coal powder concentration, it is determined that the severity of coal powder settlement and accumulation in the wellbore 16 is high;

[0055] At the same time, three different disturbance instructions are respectively input corresponding to the three levels of the severity of coal powder settlement and accumulation in the wellbore 16: When the severity of coal powder settlement and accumulation in the wellbore 16 is low, the corresponding disturbance instruction is to perform disturbance once every 2 hours within 24 hours. When the severity of coal powder settlement and accumulation in the wellbore 16 is medium, the corresponding disturbance instruction is to perform disturbance once every 1 hour within 24 hours. When the severity of coal powder settlement and accumulation in the wellbore 16 is high, the corresponding disturbance instruction is to perform disturbance once every 0.5 hour within 24 hours.

[0056] Step (iv) is specifically as follows: After starting the pump, the sucker rod 4 rotates self - sufficiently, and the normal drainage of coalbed methane begins. The capacitive density sensor 5 monitors the coal powder concentration in the wellbore 16 in real - time and transmits the coal powder concentration information to the computer remote control system 3. The display interface of the computer remote control system 3 displays the coal powder concentration in real - time:

[0057] a. The alarm 2 emits an alarm signal:

[0058] During the normal drainage process, when the buzzer 13 emits an alarm sound and the green light on the alarm 2 turns into a red light, it is determined that the coal powder concentration exceeds the standard, that is, the coal powder concentration in the wellbore 16 is abnormal;

[0059] b. Determine the severity of coal powder settlement and accumulation in the wellbore 16, and trigger the computer remote control system 3 to issue corresponding disturbance instructions:

[0060] After the alarm 2 emits an alarm signal, the control software built - in the computer remote control system 3 determines whether the severity of coal powder settlement and accumulation in the wellbore 16 is low, medium or high. The computer remote control system 3 controls the coal powder disturbance system to perform disturbance operations according to the corresponding disturbance instructions;

[0061] c. The coal powder disturbance system performs disturbance operations in the wellbore 16:

[0062] Taking the case where the severity of coal powder settlement and accumulation in the wellbore 16 is high as an example, the coal powder disturbance system starts to operate. The disturbance motor 9 drives the fixed pulley 8 to make periodic reciprocating rotations. Then, the reciprocating rotation of the fixed pulley 8 makes the rigid rope 11 drive the disturbance gear 10 to move up and down reciprocally in the wellbore 16. At the same time, driven by the self - rotation of the sucker rod 4, the disturbance gear 10 makes a rotational motion in the wellbore 16, so as to disturb the coal powder in the wellbore 16, prevent coal powder aggregation, and then discharge the coal powder from the wellbore 16. The up - and - down moving distance of each disturbance operation of the disturbance gear 10 is 10m, and the disturbance is carried out once every 0.5h, for a total of 48 times in 24h;

[0063] d. Re - confirm the coal powder concentration in the wellbore 16:

[0064] After the disturbance operation is completed, the coal powder in the wellbore 16 is left standing for 2h. The coal powder concentration in the wellbore 16 is the real concentration. At this time, if the coal powder concentration in the wellbore 16 is lower than the first coal powder concentration critical value, the red light on the alarm 2 automatically turns into a green light, the buzzer 13 stops emitting an alarm, and the coal powder disturbance system stops the disturbance operation. If the coal powder concentration in the wellbore 16 is still abnormal, repeat steps b and c until the coal powder concentration in the wellbore 16 is lower than the first coal powder concentration critical value, that is, the coal powder concentration in the wellbore 16 is in a normal state.

[0065] The function of the two rope positioning rings 12 is to limit the position of the rigid rope 11 and prevent the rigid rope 11 from winding around the sucker rod 4 during normal drainage due to the self - rotation of the sucker rod 4.

[0066] The present invention can monitor the pulverized coal in the drainage wellbore 16 in real time and disturb it, prevent the pulverized coal from settling and accumulating in the wellbore 16, reduce the number of workover operations, and realize the normal production and drainage of coalbed methane wells.

[0067] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be modified or equivalently replaced, and any modification or partial replacement without departing from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. A method for preventing coal dust settlement in the wellbore during the drainage of coalbed methane wells, characterized in that: The specific steps include: (1) Assembling a coalbed methane drainage and coal dust anti-settling device, the coalbed methane drainage and coal dust anti-settling device comprising a coal dust monitoring system, a coal dust disturbance system, a signal transmitter, an alarm and a computer remote control system, the coal dust monitoring system and the coal dust disturbance system are both installed on the outer circumference of a certain oil-saving rod, the coal dust monitoring system is located at the lower side of the coal dust disturbance system, the signal transmitter is installed on the oil-saving rod closest to the ground, the alarm and the computer remote control system are arranged in a control room on the ground, the computer remote control system is respectively connected to the signal transmitter and the alarm signal, the signal transmitter is respectively connected to the coal dust monitoring system and the coal dust disturbance system signal, and the coal dust disturbance system is electrically connected to the ground power supply; (ii) lowering the coal powder monitoring system and the coal powder disturbance system together with the oil rod into the target position in the oil pipe in the wellbore; (3) Inputting the critical value of coal powder concentration and disturbance instruction into the computer remote control system; (iv) Start the pump to drain coalbed methane normally, and monitor the coal powder concentration in the wellbore in real time through the coal powder monitoring system. If the coal powder concentration is abnormal, control the coal powder disturbance system to perform corresponding disturbance operations in the wellbore to prevent coal powder from settling and agglomerating; (V) When the coal powder concentration returns to normal, the coal powder disturbance system stops the disturbance operation and the coal powder monitoring system enters the normal monitoring state; The coal powder monitoring system includes a capacitive density sensor, which is fixedly connected to a certain oil section rod through a hoop, and a signal transmitter is fixedly connected to the middle of the outer wall of an oil section rod closest to the ground through a hoop, and the signal transmitter is connected to the capacitive density sensor signal; The coal powder disturbance system includes a C-type support, a fixed pulley, a disturbance motor, a disturbance gear, a rigid rope and two rope positioning rings. The upper side, the lower side and the outer side of the C-type support are all open. The C-type support is fixedly connected to a fuel-saving rod above the capacitive density sensor through a hoop. The fixed pulley is rotatably installed in the C-type support. The disturbance motor is fixedly installed on the side plate of the C-type support. The power shaft of the disturbance motor is coaxially connected to the central axis of the fixed pulley. The disturbance gear is arranged below the fixed pulley. One end of the rigid rope is fixedly wound around the fixed pulley, and the other end of the rigid rope extends downward from the fixed pulley and is fixedly connected to the disturbance gear. The two rope positioning rings are arranged at intervals up and down and are fixedly connected to a fuel-saving rod between the fixed pulley and the disturbance gear through a hoop. The rigid rope vertically passes through the two rope positioning rings. The disturbance gear is equipped with an electronic positioner. The signal transmitter is respectively connected to the disturbance motor and the electronic positioner signal, and the disturbance motor is electrically connected to the ground power supply.

2. The method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells according to claim 1, characterized in that: The alarm is equipped with a built-in buzzer and three signal indicator lights, which are green, yellow and red respectively. The computer remote control system is connected with the buzzer and the three signal indicator lights respectively.

3. The method for preventing coal dust settlement in the wellbore during the drainage of coalbed methane wells according to claim 2, wherein: The computer remote control system and the signal transmitter are connected to each other, as are the signal transmitter and the capacitive density sensor, the disturbance motor and the electronic positioner through corrosion-resistant signal cables. Each corrosion-resistant signal cable is fixedly connected to the corresponding fuel-saving rods through a number of hoops spaced apart vertically.

4. The method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells according to claim 3, characterized in that: The distance between the two rope positioning rings and the distance between the fixed pulley and the upper rope positioning ring are both 5 m. Initially, the disturbing gear is located above the capacitive density sensor and the distance from the capacitive density sensor is less than 0.5 m.

5. The method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells according to claim 4, characterized in that: Step (2) is specifically as follows: After assembling and debugging the coalbed methane drainage and coal powder anti-settlement device according to the design requirements, based on past data, determine the section in the wellbore where coal powder is likely to accumulate, calculate the lowering depth of the capacitive density sensor, and lower the capacitive density sensor into the tubing in the wellbore together with the sucker rod. At the same time, the coal powder disturbing system is also lowered into the tubing in the wellbore together with the sucker rod. The position of the disturbing gear in the wellbore can be obtained through the electronic locator. Stop lowering the sucker rod until the disturbing gear is lowered to the section in the wellbore where coal powder is likely to accumulate, so as to lower the capacitive density sensor to the calculated depth.

6. The method for preventing coal powder settlement in the wellbore during the drainage of coalbed methane wells according to claim 5, characterized in that: Step (3) is specifically as follows: The staff inputs three gradually increasing critical values of coal powder concentration into the control software built into the computer remote control system. When the coal powder concentration in the wellbore is lower than the first critical value of coal powder concentration, it is determined that the coal powder concentration in the wellbore is normal, and the green light on the alarm goes on. When the coal powder concentration in the wellbore exceeds the first critical value of coal powder concentration, it is determined that the coal powder concentration in the wellbore is abnormal, that is, the coal powder in the wellbore settles and accumulates, the buzzer gives an alarm, and the red light on the alarm goes on. If the entire device fails, the yellow light on the alarm goes on; When the coal powder concentration in the wellbore is abnormal, the control software built into the computer remote control system determines the severity of the coal powder settlement and accumulation in the wellbore according to the three critical values of coal powder concentration, and classifies the severity of the coal powder settlement and accumulation in the wellbore into three levels: low, medium, and high. When the coal powder concentration in the wellbore exceeds the first critical value of coal powder concentration and is lower than the second critical value of coal powder concentration, it is determined that the severity of the settlement and accumulation is low. When the coal powder concentration in the wellbore exceeds the second critical value of coal powder concentration and is lower than the third critical value of coal powder concentration, it is determined that the severity of the coal powder settlement and accumulation in the wellbore is medium. When the coal powder concentration in the wellbore exceeds the third critical value of coal powder concentration, it is determined that the severity of the coal powder settlement and accumulation in the wellbore is high; At the same time, input three different disturbing instructions corresponding to the three levels of the severity of the coal powder settlement and accumulation in the wellbore: When the severity of the coal powder settlement and accumulation in the wellbore is low, the corresponding disturbing instruction is to perform disturbance once every 2 h within 24 h. When the severity of the coal powder settlement and accumulation in the wellbore is medium, the corresponding disturbing instruction is to perform disturbance once every 1 h within 24 h. When the severity of the coal powder settlement and accumulation in the wellbore is high, the corresponding disturbing instruction is to perform disturbance once every 0.5 h within 24 h.

7. The method for preventing coal dust settlement in the wellbore during the drainage of coalbed methane wells according to claim 6, characterized in that: Step (4) is specifically as follows: After starting the pump, the sucker rod rotates self-driven, and the normal drainage of coalbed methane begins. The capacitive density sensor monitors the coal powder concentration in the wellbore in real time and transmits the coal powder concentration information to the computer remote control system. The display interface of the computer remote control system displays the coal powder concentration in real time: a. The alarm gives an alarm signal: During the normal drainage process, when the buzzer gives an alarm sound and the green light on the alarm jumps to the red light, it is determined that the coal powder concentration exceeds the standard, that is, the coal powder concentration in the wellbore is abnormal; b. Determine the severity of coal powder settlement and accumulation in the wellbore, and trigger the computer remote control system to issue corresponding disturbance instructions: After the alarm signal is sent by the alarm, the control software built in the computer remote control system determines that the severity of coal powder settlement and accumulation in the wellbore is low, medium or high. The computer remote control system controls the coal powder disturbance system to perform disturbance operations according to the corresponding disturbance instructions; c. The coal powder disturbance system performs disturbance operations in the wellbore: Taking the case where the severity of coal powder settlement and accumulation in the wellbore is high as an example, the coal powder disturbance system starts to operate. The disturbance motor drives the fixed pulley to make periodic reciprocating rotations. Then, the reciprocating rotation of the fixed pulley causes the rigid rope to drive the disturbance gear to move up and down reciprocally in the wellbore. At the same time, driven by the self-rotation of the oil rod, the disturbance gear makes a rotational motion in the wellbore, so that the disturbance gear disturbs the coal powder in the wellbore, prevents the coal powder from accumulating, and then discharges the coal powder out of the wellbore. The up and down moving distance of each disturbance operation of the disturbance gear is 10m, and the disturbance is carried out once every 0.5h, for a total of 48 times within 24h; d. Reconfirm the coal powder concentration in the wellbore: After the disturbance operation is over, the coal powder in the wellbore is allowed to stand for 2h, and the coal powder concentration in the wellbore is the true concentration. At this time, if the coal powder concentration in the wellbore is lower than the first coal powder concentration critical value, the red light on the alarm automatically turns into a green light, the buzzer stops sounding the alarm, and the coal powder disturbance system stops the disturbance operation. If the coal powder concentration in the wellbore is still abnormal, repeat steps b and c until the coal powder concentration in the wellbore is lower than the first coal powder concentration critical value, that is, the coal powder concentration in the wellbore is in a normal state.

Images