A device for detecting the thickness of sediment at the bottom of a coalbed methane well

Abstract

The present invention discloses a device for detecting the thickness of bottom sediment in a coalbed methane well, comprising: a pressure-bearing body having a window on the side and an opening at the bottom; a controller sealed within the pressure-bearing body; a detector unit movably disposed at the window, the detector unit being electrically connected to the controller to provide feedback on the time when the detector unit successively receives reflected waves from different interfaces; a radial electric expander disposed within the pressure-bearing body, the action end of the radial electric expander being connected to the detector unit to control the radial extension and reset of the detector unit, the radial electric expander being electrically connected to the controller to be controlled by the controller; and an ultrasonic generator disposed within the opening, the ultrasonic generator emitting ultrasonic waves in a downward direction, the ultrasonic generator being electrically connected to the controller to be controlled by the controller. By obtaining the propagation time of the ultrasonic wave and according to the propagation speed of the high-frequency signal in water, coal powder, and quartz sand, which has been calibrated in advance, the thickness of the coal powder and quartz sand can be measured.

Description

Technical Field

[0001] The invention relates to the technical field of coalbed methane mining, and in particular to a device for detecting the thickness of bottom sediments in a coalbed methane well. Background Art

[0002] Coalbed methane (primarily methane) refers to unconventional natural gas adsorbed on the microporous surfaces and within coal particles. Since coalbed methane primarily exists in an adsorbed state on these surfaces and within coal particles, with a small amount remaining in a free state within the microcracks of the coal seam, its extraction requires hydraulic fracturing to create numerous fractures in the formation to create flow channels. This, combined with the reduction of the liquid column in the wellbore to reduce pressure on the coal rock, allows the methane adsorbed on the coal's microporous surfaces to desorb and flow into the wellbore along the channels created by the fracturing until it is extracted to the surface.

[0003] In coalbed methane (CBM) wells, hydraulic fracturing causes the coal seam to fracture and produces a large amount of coal dust. During the long CBM production process, some of the coal dust and fracturing proppant (quartz sand) are carried into the wellbore by water and gas, where they continuously settle and accumulate. Quartz sand forms the bottom, coal dust forms above it, and a liquid column (water) forms above the coal dust. The exact thickness of the quartz sand and coal dust at the bottom of the wellbore is often unknown. Excessive accumulation of sand and coal dust can affect CBM well production and can easily cause pump jamming during pumping. Summary of the Invention

[0004] To this end, the present invention provides a device for detecting the thickness of bottom sediments in a coalbed methane well, so as to solve the technical problem that the accumulation thickness of quartz sand and coal powder at the bottom of the wellbore is unknown.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A device for detecting the thickness of sediment at the bottom of a coalbed methane well, comprising:

[0007] A pressure-bearing body with windows on the sides and an opening at the bottom;

[0008] A controller sealed in the pressure-bearing body, the controller having a timing unit;

[0009] a wave detector unit movably arranged at the window, the wave detector unit being electrically connected to the controller to feed back the moments when the wave detector unit successively receives reflected waves from different interfaces;

[0010] a radial electric expander disposed in the pressure-bearing body, wherein an actuating end of the radial electric expander is connected to the wave detection unit to control radial extension and resetting of the wave detection unit, and the radial electric expander is electrically connected to the controller to be controlled by the controller;

[0011] An ultrasonic generator is arranged in the opening, and the ultrasonic wave emission direction of the ultrasonic generator faces downward. The ultrasonic generator is electrically connected to the controller to be controlled by the controller.

[0012] Furthermore, the detection unit includes a detector bracket and a piezoelectric detector. The detector bracket is slidably arranged at the window. The piezoelectric detector is arranged in the detector bracket with the ultrasonic receiving end of the piezoelectric detector facing downward. The piezoelectric detector is electrically connected to the controller.

[0013] Furthermore, the detector unit further includes a buffer pad, which is arranged on a side of the detector bracket away from the radial electric expander.

[0014] Furthermore, the radial electric telescoping device is an X-type horizontal and vertical motion converter, which includes a guide plate, a motor, a first support rod, a second support rod, a traction rod and a push plate. The guide plate is provided with a vertical guide groove, and a rack is provided on the vertical side of the guide groove. The motor can be slidably arranged on one side of the guide plate along the length direction of the guide groove. A driving wheel engaged with the rack is provided on the output shaft of the motor. The first end of the first support rod is pivoted to the guide plate, and the second end is pivoted to the push plate. Both the guide plate and the push plate are provided with a vertical sliding groove. The first end of the second support rod is slidably arranged in the sliding groove of the guide plate, and the second end is slidably arranged in the sliding groove of the push plate. The first end of the traction rod is pivoted to the shaft end of the output shaft of the motor, and the second end is pivoted to the first end of the second support rod.

[0015] Furthermore, the guide plate and / or the motor are slidably fixed vertically in the pressure-bearing body; the first end of the second support rod is slidably set in the sliding groove of the guide plate through a grooved pulley, and the second end is slidably set in the sliding groove of the push plate through a grooved pulley.

[0016] Furthermore, the detector bracket and the window opening are in rolling friction.

[0017] Furthermore, the device for detecting the thickness of bottom sediments in a coalbed methane well also includes a control module, which is sealed in the pressure-bearing body and electrically connected to the controller and the ultrasonic generator respectively.

[0018] Furthermore, the device for detecting the thickness of bottom sediments in a coalbed methane well also includes an acoustic wave energy focusing hood, which is arranged under the bottom opening of the pressure-bearing body.

[0019] The present invention has the following advantages:

[0020] After the coalbed methane well has been working for a certain period of time, the ground issues a detection command, and the controller controls the radial electric expansion joint to move, so that the detection unit extends from the side window of the pressure-bearing body to receive the ultrasonic reflection wave. The controller controls the ultrasonic generator to emit continuous high-frequency signals. At the same time, the controller starts timing, and the ultrasonic wave propagates toward the lower part of the wellbore. The vibration wave encounters the water-coal powder, coal powder-quartz sand and quartz sand-bottomhole interfaces in turn and reflects upward. At this time, the detection unit receives the reflection waves from different interfaces and feeds back the time of receiving the reflection wave to the controller, so that the corresponding propagation time can be obtained. According to the pre-calibrated high-frequency signal propagation speed in water, coal powder and quartz sand media, the thickness of coal powder and quartz sand can be measured. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can, without inventive effort, derive other implementation drawings based on the provided drawings.

[0022] The structures, proportions, sizes, etc. illustrated in this specification are intended solely to complement the contents disclosed herein and to facilitate understanding and reading by persons skilled in the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall remain within the scope of the technical contents disclosed herein.

[0023] Figure 1 A schematic structural diagram of a device for detecting the thickness of sediment at the bottom of a coalbed methane well provided in Example 1 of the present invention;

[0024] Figure 2 A schematic diagram of the structure of the device for detecting the thickness of sediment at the bottom of a coalbed methane well provided in Example 1 of the present invention when working at the bottom of the well;

[0025] Figure 3 This is a schematic structural diagram of the radial electric expansion joint of the device for detecting the thickness of bottom sediments in a coalbed methane well provided in Example 2 of the present invention.

[0026] In the figure: 1-pressure-bearing body; 2-controller; 3-radial electric expander, 31-guide plate, 32-motor, 33-first support rod, 34-second support rod, 35-traction rod, 36-push plate, 37-driving wheel, 38-grooved pulley, 311-guide groove, 312-rack, 313-sliding groove; 4-detection unit, 41-detector bracket, 42-piezoelectric detector, 43-buffer pad; 5-control module; 6-ultrasonic generator; 7-sound wave energy focusing cover; 8-casing. DETAILED DESCRIPTION

[0027] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0028] The terms "upper", "lower", "left", "right", "middle", etc. used in this specification are only for the convenience of description and are not intended to limit the scope of the present invention. Changes or adjustments to their relative relationships should be regarded as within the scope of the present invention without substantially changing the technical content.

[0029] Example 1

[0030] like Figure 1 and 2 As shown, this embodiment provides a device for detecting the thickness of bottom sediments in a coalbed methane well, comprising a pressure-bearing body 1, a controller 2, a radial electric expander 3, a detector unit 4, a control module 5, an ultrasonic generator 6 and an acoustic wave energy focusing cover 7, wherein the sediments are quartz sand and coal powder.

[0031] The pressure-bearing body 1 is cylindrical as a whole, with the upper end connected to the pipe column. A pipe buckle is generally provided at the upper end, and an opening is provided at the lower end to allow ultrasonic waves to be emitted downward; a window is provided on the side for setting a radial electric expander 3 and a detection unit 4.

[0032] Controller 2 is typically a PLC controller 2, such as the one in the Tianlang TL-2G. Controller 2 is sealed within the pressure-bearing body 1, above the window opening. It is used to receive control signals (commands) from the surface, transmit relevant times to the surface (e.g., via communication or data lines), and receive electrical energy from the surface (e.g., via cables) and transmit it to the radial electric expansion joint 3, detector unit 4, control module 5, and ultrasonic generator 6. Controller 2 includes a timing unit that measures the time from ultrasonic emission to the moment the reflected ultrasonic wave (reflected waves from the water-coal, coal-quartz sand, and quartz sand-bottomhole interfaces) is received (detected, measured, or sensed) by the detector unit 4.

[0033] The radial electric expansion joint 3 is disposed within the pressure-bearing body 1, generally at the same height as the window opening. It is used to push the detector unit 4 out of the pressure-bearing body 1 through the window opening so that the detector unit 4 can receive the reflected wave. It is also used to retract the detector unit 4 from the pressure-bearing body 1, resetting it and facilitating the removal of the tool (a device for detecting the thickness of bottom sediment in a coalbed methane well) by lifting the pipe string. The radial electric expansion joint 3 is electrically connected to the controller 2 and operates under the control of the controller 2.

[0034] The detector unit 4 is movably arranged at the window opening. The detector unit 4 is electrically connected to the controller 2. When the detector unit 4 receives the reflected wave, it sends the time of receiving the reflected wave to the controller 2 (actually sending an electrical signal). The controller 2 calculates the time based on the signal. The detector unit 4 will receive a total of three reflected waves from the water-coal powder, coal powder-quartz sand, and quartz sand-bottomhole interfaces. Specifically, the detector unit 4 includes a detector bracket 41, a piezoelectric detector 42, and a buffer pad 43. The detector bracket 41 is slidably arranged at the window opening. The piezoelectric detector 42 is arranged in the detector bracket 41, with the ultrasonic receiving end of the piezoelectric detector 42 facing downward. The piezoelectric detector 42 is electrically connected to the controller 2. The piezoelectric detector 42 can be a DS-S1000 marine geophysical piezoelectric detector 42. The buffer pad 43 is arranged on the side of the detector bracket 41 away from the radial electric expander 3.

[0035] The control module 5 is sealed in the pressure-bearing body 1, located between the bottom opening and the side window, and is electrically connected to the controller 2 and the ultrasonic generator 6 respectively, and is used to: receive the ultrasonic emission instruction sent by the controller 2 and control the ultrasonic generator 6 to emit ultrasonic waves.

[0036] The ultrasonic generator 6 is arranged in the opening, and the ultrasonic wave emission direction of the ultrasonic generator 6 is downward. The ultrasonic generator 6 is electrically connected to the controller 2 so as to be controlled by the controller 2; generally, a control module 5 is arranged between the ultrasonic generator 6 and the controller 2.

[0037] The sound wave energy focusing cover 7 is arranged under the bottom opening of the pressure-bearing body 1 and is used to concentrate the ultrasonic waves and emit them downward.

[0038] After the coalbed methane well has been working for a certain period of time, the ground sends a detection instruction, and the controller 2 controls the radial electric expansion joint 3 to move, so that the detector bracket 41 extends from the side window of the pressure-bearing body 1. After the extension, the piezoelectric detector 42 is in the annulus between the pressure-bearing body 1 and the casing 8, which is convenient for receiving the ultrasonic reflection wave of the sediment interface at the bottom of the well; the controller 2 instructs the control module 5 to move, and controls the ultrasonic generator 6 to emit a continuous high-frequency signal. At the same time, the controller 2 starts timing; the ultrasonic wave is concentrated by the acoustic wave focusing cover 7 and propagates downward along the wellbore. The vibration wave encounters water-coal powder, coal powder-quartz and other materials in turn. Sand and quartz sand-bottom-hole interface and reflected upwards. At this time, the piezoelectric detector 42 receives the reflected waves from different interfaces and feeds back the time of receiving the reflected waves to the controller 2 (actually, it is a feedback electrical signal. The controller 2 stops timing a reflected wave based on the signal; other reflected waves continue timing), so that the corresponding propagation time can be obtained; by recording the time, according to the propagation speed of the high-frequency signal in water, coal powder and quartz sand media that has been calibrated in advance, the thickness of the coal powder and quartz sand can be measured; when the thickness exceeds a certain value, gas production is suspended, and gas production is resumed after the coal powder and quartz sand at the bottom of the well are cleaned up.

[0039] Example 2

[0040] In this embodiment, the radial electric expander is an X-shaped horizontal and vertical motion converter. Figure 3 As shown, the X-type horizontal and vertical motion converter includes a guide plate 31, a motor 32, a first support rod 33, a second support rod 34, a traction rod 35 and a push plate 36. The guide plate 31 is provided with a vertical guide groove 311, and a rack 312 is provided on the vertical side of the guide groove 311. The motor 32 can be slidably arranged on one side of the guide plate 31 along the length direction of the guide groove 311. A driving wheel 37 engaged with the rack 312 is provided on the output shaft of the motor 32. The first end of the first support rod 33 is pivoted to the guide plate 31, and the second end is pivoted to the push plate 36. The guide plate 31 and the push plate 36 are both provided with a vertical sliding groove 313. The first end of the second support rod 34 is slidably set in the sliding groove 313 of the guide plate 31, and the second end is slidably set in the sliding groove 313 of the push plate 36. The first end of the traction rod 35 is pivoted to the shaft end of the output shaft of the motor 32, and the second end is pivoted to the first end of the second support rod 34.

[0041] The push plate 36 may be an independent component or a side wall plate of the detector bracket.

[0042] Figure 3 In the embodiment, racks 312 are provided on both vertical sides of the guide groove 311, and the driving wheel 37 can mesh with either of the two racks 312, but not both at the same time.

[0043] Optionally, the first end of the second support rod 34 is slidably disposed in the sliding groove 313 of the guide plate 31 through the groove pulley 38 , and the second end is slidably disposed in the sliding groove 313 of the push plate 36 through the groove pulley 38 .

[0044] Optionally, the guide plate 31 and / or the motor 32 are slidably fixed in the pressure-bearing body along the vertical direction, and the guide plate 31 and the motor 32 are relatively displaced relative to the pressure-bearing body, thereby ensuring that the detection unit does not move up and down during radial expansion and contraction.

[0045] Example 3

[0046] In this embodiment, the radial electric expander is an electric push rod, which is arranged in a direction perpendicular to the axis of the pressure-bearing body, has a body sealed and fixed in the pressure-bearing body, and is connected to the detector bracket.

[0047] Using an electric push rod to push out or pull back the detector bracket can prevent the detector bracket from being displaced in the vertical direction (once it is displaced, it is likely to be stuck in the window position), but the structure is simpler than that of embodiment 2.

[0048] Example 4

[0049] In this embodiment, rolling friction is achieved between the detector bracket and the window opening. For example, rollers or balls are positioned at the edge of the window opening. The detector bracket and the roller surface or the spherical surface of the ball abut against each other, creating rolling friction. The placement of rollers and balls at the edge of the window opening is well known to those skilled in the art and will not be further described here. This rolling friction ensures smooth movement of the detector bracket while reducing friction.

[0050] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A device for detecting the thickness of sediment at the bottom of a coalbed methane well, characterized in that: include: A pressure-bearing body with windows on the sides and an opening at the bottom; A controller sealed in the pressure-bearing body, the controller having a timing unit; a wave detector unit movably arranged at the window, the wave detector unit being electrically connected to the controller to feed back the moments when the wave detector unit successively receives reflected waves from different interfaces; a radial electric expander disposed in the pressure-bearing body, wherein an actuating end of the radial electric expander is connected to the wave detection unit to control radial extension and resetting of the wave detection unit, and the radial electric expander is electrically connected to the controller to be controlled by the controller; An ultrasonic generator is disposed in the opening, wherein the ultrasonic wave emission direction of the ultrasonic generator is downward, and the ultrasonic generator is electrically connected to the controller to be controlled by the controller; The detector unit includes a detector bracket, a piezoelectric detector and a buffer pad, the detector bracket is slidably arranged at the window, the piezoelectric detector is arranged in the detector bracket with the ultrasonic receiving end of the piezoelectric detector facing downward, the piezoelectric detector is electrically connected to the controller, and the buffer pad is arranged on a side of the detector bracket away from the radial electric expander; The radial electric telescoping device is an X-type horizontal and vertical motion converter, which includes a guide plate, a motor, a first support rod, a second support rod, a traction rod and a push plate. The guide plate is provided with a vertical guide groove, and a rack is provided on the vertical side of the guide groove. The motor can be slidably arranged on one side of the guide plate along the length direction of the guide groove. A driving wheel engaged with the rack is provided on the output shaft of the motor. The first end of the first support rod is pivotally connected to the guide plate, and the second end is pivotally connected to the push plate. Both the guide plate and the push plate are provided with a vertical sliding groove. The first end of the second support rod is slidably arranged in the sliding groove of the guide plate, and the second end is slidably arranged in the sliding groove of the push plate. The first end of the traction rod is pivoted to the shaft end of the output shaft of the motor, and the second end is pivoted to the first end of the second support rod.

2. The device for detecting the thickness of bottom sediment in a coalbed methane well according to claim 1, characterized in that: The guide plate and / or the motor are slidably fixed in the pressure-bearing body vertically; the first end of the second support rod is slidably set in the sliding groove of the guide plate through a grooved pulley, and the second end is slidably set in the sliding groove of the push plate through a grooved pulley.

3. The device for detecting the thickness of bottom sediment in a coalbed methane well according to claim 1, characterized in that: The detector bracket and the window opening are in rolling friction.

4. The device for detecting the thickness of bottom sediment in a coalbed methane well according to claim 1, characterized in that: The device for detecting the thickness of bottom sediments in a coalbed methane well further comprises a control module, which is sealed in the pressure-bearing body and electrically connected to the controller and the ultrasonic generator respectively.

5. The device for detecting the thickness of sediment at the bottom of a coalbed methane well according to claim 1 is characterized in that The device for detecting the thickness of bottom sediments in a coalbed methane well further comprises an acoustic wave energy focusing hood, which is arranged under the bottom opening of the pressure-bearing body.

Images