A drilling fluid flow control device for improving reliability of MWD signals

Abstract

This application provides a drilling fluid flow control device to improve the reliability of MWD signals. It addresses the problem of poor MWD signal transmission stability during annular return loss in drilling operations. The device includes a slidingly sleeved outer shell assembly and a sliding flow control assembly, with a return spring between the sliding flow control assembly and the outer shell assembly. The outer shell assembly includes an upper connector assembly, and the sliding flow control assembly includes a flow control upper sleeve. The outer wall of the flow control upper sleeve has several first inlet holes communicating with its inner bore. When the return spring is in a free state, all the first inlet holes are connected to the inlet end of the upper connector assembly. An air bladder is installed inside the upper connector assembly. When the air bladder is inflated, the sliding flow control assembly slides along the inner wall of the outer shell assembly, blocking some or all of the first inlet holes from the inlet end of the upper connector assembly. This application increases the flow resistance within the drill string, thereby reducing the pressure of the drilling fluid and improving the reliability of MWD signal transmission.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well engineering, and in particular to a drilling fluid flow control device for improving the reliability of MWD signals. Background Technology

[0002] Measurement while drilling (MWD) is a technology that measures drilling parameters and formation information near the drill bit during the drilling process and transmits this information to the surface via mud pulses without interrupting normal drilling operations.

[0003] Through MWD technology, drilling personnel can promptly understand the actual situation downhole, thereby adjusting drilling strategies and ensuring the smooth progress of drilling operations. Currently, there are two main methods for transmitting information during drilling: wired and wireless transmission. MWD commonly uses wireless transmission, which typically employs three methods: drilling fluid pulse method, acoustic method, and electromagnetic wave method. Each method has its applicable scope and limitations. Compared to the above three wireless transmission methods, the mud pulse wireless transmission method is the most widely used. It uses circulating drilling fluid as the transmission medium, converting the detected signal into a pulse wave generated by a flow control device to transmit the signal. Its technology is relatively mature, the process is relatively simple, it is easy to implement in actual working conditions, and its performance is relatively reliable, making it the most widely used downhole information transmission method. However, many factors affect MWD instrument measurements, including instrument connection, drilling fluid circulation system and drill bit noise, well depth, and drilling fluid performance adjustments, all of which affect instrument signal transmission.

[0004] When wellbore leakage occurs, drilling fluid leaks into the formation fractures within the annulus. If the downhole leakage rate exceeds the drilling mud pumping rate, the annulus fluid cannot be replenished in time, leading to a drop in the drilling fluid level in the annulus. This directly results in a decrease in the hydrostatic pressure of the drilling fluid column. Consequently, the drilling fluid cannot flow stably and continuously through the MWD (Micro-Drilling Surface), affecting the reception and transmission of MWD signals. Therefore, equipment is needed to ensure the reliability of the MWD signal in the event of wellbore leakage or annulus return loss due to other reasons.

[0005] Currently, domestic and international research on stabilizing MWD signals and eliminating signal influencing factors includes the following: Research on mud pulse signal extraction and identification mainly involves: detailed analysis of mud pulse signals and existing noise interference sources in wireless measurement-while-drilling systems; and discussion of methods using wavelet neural network threshold denoising technology to detect effective signals from multi-frequency, high-noise backgrounds with variable frequencies. Existing research has established transfer function models for various components in the mud channel (flexible or rigid drill pipe, air bag, sudden contraction / expansion pipe, choke orifice, etc.), and modularized them for arbitrary assembly to simulate different drill string structures, focusing on the impact of surface pipelines such as risers and air bags on signal quality. Existing research has conducted in-depth studies on the transmission speed of pressure wave signals, investigating the effects of drilling fluid density, gas content, solids concentration, drilling fluid type, and diameter-to-thickness ratio on signal transmission speed; Wang Xiang proposed the frequency domain transmission speed of pressure wave signals and analyzed its influencing factors. However, the above methods suffer from complex models and high computational costs. Summary of the Invention

[0006] The purpose of this invention is to provide a drilling fluid flow control device that improves the reliability of MWD signals. It addresses the technical problem of poor MWD signal transmission stability when existing drill strings experience lost circulation and annular return during drilling. This is caused by the annular fluid level dropping to a certain level due to rapid loss of fluid and insufficient replenishment, leading to a suction effect on the fluid within the drill string and resulting in negative pressure in the drilling fluid circulating within the drill string.

[0007] A drilling fluid flow control device for improving the reliability of MWD signals includes a housing assembly, a sliding flow control component slidably disposed within the housing assembly, and a return spring disposed between the sliding flow control component and the housing assembly.

[0008] The outer casing assembly includes an upper connector assembly, and the sliding flow control assembly includes a flow control upper sleeve. The outer wall of the flow control upper sleeve is provided with a plurality of first liquid inlet holes communicating with its inner hole. When the reset spring is in a free state, the plurality of first liquid inlet holes are all connected to the liquid inlet end of the upper connector assembly.

[0009] An air bladder is provided inside the upper connector assembly. When the air bladder is inflated, the sliding flow control component slides along the inner wall of the outer shell assembly, causing part or all of the first liquid inlet holes to block the liquid inlet end of the upper connector assembly.

[0010] Optionally, the lower end of the upper connector assembly is provided with a first sliding hole along the axial direction, and the upper end of the upper connector assembly is provided with a second liquid inlet hole along the axial direction.

[0011] The first sliding hole and the second liquid inlet hole are connected. The diameter of the second liquid inlet hole is larger than the diameter of the first sliding hole. The flow control upper sleeve is slidably disposed in the first sliding hole. When the reset spring is in a free state, all of the first liquid inlets are connected to the second liquid inlet holes.

[0012] Optionally, a limit sleeve is connected to the upper end of the flow control upper sleeve;

[0013] The outer diameter of the limiting sleeve is larger than the outer diameter of the flow control upper sleeve, and the inner diameter of the limiting sleeve is smaller than the inner diameter of the flow control upper sleeve.

[0014] Optionally, a plurality of the first liquid inlet holes are arranged in an annular array on multiple annular planes in the direction of the axial axis of the flow control sleeve.

[0015] Optionally, the housing assembly further includes an intermediate connector sleeve and a lower connector assembly;

[0016] One end of the intermediate connector sleeve is connected to the outer wall of the middle part of the upper connector assembly, and the other end of the intermediate connector sleeve is connected to one end of the lower connector assembly. The lower connector assembly is provided with a second sliding hole along the axial direction.

[0017] Optionally, the lower end of the upper flow control sleeve is connected to a lower flow control sleeve, and the lower flow control sleeve is slidably disposed in the second sliding hole;

[0018] A limiting flange is provided at the upper end of the flow control sleeve. The limiting flange is located in the piston cavity between the upper connector assembly and the lower connector assembly. The outer wall of the limiting flange slides along the inner wall of the intermediate connector sleeve. The return spring is disposed between the limiting flange and the lower connector assembly.

[0019] Optionally, a placement groove is provided on the outer wall of the upper connector assembly, and the placement groove and the inner wall of the intermediate connector sleeve form a placement cavity for placing the airbag;

[0020] The upper connector assembly has an air inlet channel connecting the outer wall of the upper connector assembly to the airbag inside the placement cavity, a first flow channel connecting the placement cavity to the piston cavity, a second flow channel connecting the piston cavity to the outer wall of the upper connector assembly, and a third flow channel connecting the placement cavity to the second flow channel.

[0021] Optionally, a one-way pressure balancing valve is provided in the second flow channel, and a one-way inflation valve is provided in the air intake channel.

[0022] Optionally, a third liquid inlet is provided on the outer wall of the intermediate joint sleeve, which communicates with the piston chamber, and the third liquid inlet is located at the lower part of the piston chamber.

[0023] Optionally, O-rings are provided between the upper connector assembly and the upper flow control sleeve, and between the lower connector assembly and the lower flow control sleeve.

[0024] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0025] 1. The flow control device of this application reduces the pressure of drilling fluid in the drill string by increasing the flow resistance in the drill string, thereby reducing the probability of negative pressure in the drill string and improving the reliability of MWD signal transmission.

[0026] 2. This application controls the up-and-down movement of the sliding flow control component by inflating the airbag to expand its volume. By controlling the number of first inlet holes connected to the second inlet hole, the cross-sectional area of ​​the flow channel is changed. When well leakage occurs, the flow control device works faster and consumes less energy. Its structure is simple and can adapt to the high temperature and high pressure conditions downhole without failing.

[0027] 3. The working principle of the flow control device in this application is based on Bernoulli's principle and the continuity equation. When fluid passes through the flow control device, the reduction in the cross-sectional area of ​​the pipe leads to an increase in flow velocity. At this time, the kinetic energy of the liquid increases, while the total energy remains constant. Therefore, the energy conversion that occurs when the liquid passes through the flow control device manifests as a pressure decrease.

[0028] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0029] The accompanying drawings of this invention are described below.

[0030] Figure 1 This is a cross-sectional view of the drilling fluid flow control device of the present invention.

[0031] Figure 2 This is a three-dimensional structural view of the drilling fluid flow control device of the present invention.

[0032] Figure 3 This is a cross-sectional view of the connector assembly of the present invention.

[0033] Figure 4 For the present invention Figure 3 Sectional view at point AA.

[0034] Figure 5 This is a three-dimensional structural view of the connector assembly of the present invention.

[0035] Figure 6This is a schematic diagram of the sliding flow control component of the present invention.

[0036] Figure 7 This is a cross-sectional view of the connector assembly of the present invention.

[0037] Figure 8 This is a schematic diagram of the flow control device of the present invention during normal drilling operation.

[0038] Figure 9 This is a schematic diagram of the structure of the first liquid inlet being partially blocked when the annular return occurs according to the present invention.

[0039] Figure 10 This is a schematic diagram of the structure of the present invention where all first inlet holes are blocked when annular return fails.

[0040] Figure 11 This is a schematic diagram of the drilling fluid flow control device of the present invention at the installation position on the drill string.

[0041] In the diagram: 1-Reset spring; 2-Upper connector assembly; 201-First sliding hole; 202-Second liquid inlet; 203-Placement groove; 204-Air inlet; 205-First flow channel; 206-Second flow channel; 207-Third flow channel; 3-Flow control upper sleeve; 301-First liquid inlet; 4-Airbag; 5-Limiting sleeve; 6-Intermediate connector sleeve; 601-Piston chamber; 602-Third liquid inlet; 7-Lower connector assembly; 701-Second sliding hole; 8-Flow control lower sleeve; 801-Limiting flange; 9-One-way pressure balance valve; 10-One-way inflation valve; 11-O-ring seal. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Example:

[0044] like Figure 1 and Figure 2 The drilling fluid flow control device shown is for improving the reliability of MWD signals. It is characterized by including a housing assembly, in which a sliding flow control component is slidably disposed, and a return spring 1 is disposed between the sliding flow control component and the housing assembly.

[0045] The outer casing assembly includes an upper connector assembly 2, and the sliding flow control assembly includes a flow control upper sleeve 3. The outer wall of the flow control upper sleeve 3 is provided with a plurality of first liquid inlet holes 301 communicating with its inner hole. When the reset spring 1 is in a free state, the plurality of first liquid inlet holes 301 are all connected to the liquid inlet end of the upper connector assembly 2.

[0046] An airbag 4 is provided inside the upper connector assembly 2. When the airbag 4 is inflated, the sliding flow control component slides along the inner wall of the outer shell assembly, causing part or all of the first liquid inlet hole 301 to block the liquid inlet end of the upper connector assembly 2.

[0047] like Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the lower end of the upper connector assembly 2 is provided with a first sliding hole 201 along the axial direction, and the upper end of the upper connector assembly 2 is provided with a second liquid inlet hole 202 along the axial direction.

[0048] The first sliding hole 201 and the second liquid inlet hole 202 are connected. The diameter of the second liquid inlet hole 202 is larger than the diameter of the first sliding hole 201. The flow control upper sleeve 3 is slidably disposed in the first sliding hole 201. When the reset spring 1 is in a free state, all of the first liquid inlet holes 301 are connected to the second liquid inlet hole 202.

[0049] In this embodiment, as Figure 11 The diagram shows the installation of the flow control device. When annular return occurs, the number of first inlet holes 301 connected to the second inlet hole 202 is controlled, thereby changing the cross-sectional area of ​​the flow channel. This causes the fluid to experience resistance during passage, reducing its velocity and flow rate, thus controlling the flow rate. Specifically, when annular return occurs, the air bladder 4 inflates, driving the sliding flow control component to move, thereby controlling the fluid's flow rate and velocity. At this time, the liquid's kinetic energy increases, and its static energy decreases. According to Bernoulli's theorem, when kinetic energy increases and static energy decreases, the total energy remains constant. Therefore, the energy conversion of the drilling fluid inside the drill string as it passes through the flow control device manifests as a pressure decrease, thereby reducing the possibility of negative pressure and increasing the reliability of the MWD signal.

[0050] like Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the upper end of the flow control upper sleeve 3 is connected to the limit sleeve 5;

[0051] The outer diameter of the limiting sleeve 5 is greater than the outer diameter of the flow control upper sleeve 3, and the inner diameter of the limiting sleeve 5 is smaller than the inner diameter of the flow control upper sleeve 3.

[0052] In this embodiment, by setting the outer diameter of the limiting sleeve 5 to be larger than the outer diameter of the flow control upper sleeve 3, when the sliding flow control component moves to the bottom of its stroke, the lower end of the limiting sleeve 5 abuts against the upper end face of the first sliding hole 201, thus limiting the sliding flow control component. In this embodiment, by setting the inner diameter of the limiting sleeve 5 to be smaller than the inner diameter of the flow control upper sleeve 3, when part of the first inlet hole 301 and the second inlet hole 202 are blocked, the drilling fluid flow rate through the inner hole of the flow control upper sleeve 3 is reduced.

[0053] like Figure 1 , Figure 2 and Figure 6 As shown, a plurality of the first liquid inlet holes 301 are arranged in an annular array on multiple annular planes in the axial direction of the flow control upper sleeve 3.

[0054] In this embodiment, there are 8 first liquid inlet holes 301, which are arranged in an array in 2 annular planes.

[0055] like Figure 1 , Figure 2 and Figure 7 As shown, the outer casing assembly also includes an intermediate connector sleeve 6 and a lower connector assembly 7;

[0056] One end of the intermediate connector sleeve 6 is connected to the outer wall of the middle part of the upper connector assembly 2, and the other end of the intermediate connector sleeve 6 is connected to one end of the lower connector assembly 7. The lower connector assembly 7 is provided with a second sliding hole 701 along the axial direction.

[0057] In this embodiment, the upper and lower ends of the intermediate connector sleeve 6 are provided with internal threads, the middle diameter of the upper connector assembly 2 is reduced and the outer wall of the middle part is provided with external threads, and the outer wall of the upper end of the lower connector assembly 7 is also provided with external threads. The intermediate connector sleeve 6 is threadedly connected to both the upper connector assembly 2 and the lower connector assembly 7.

[0058] like Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the lower end of the flow control upper sleeve 3 is connected to the flow control lower sleeve 8, and the flow control lower sleeve 8 is slidably disposed in the second sliding hole 701.

[0059] The upper end of the flow control sleeve 8 is provided with a limiting flange 801. The limiting flange 801 is located in the piston cavity 601 between the upper connector assembly 2 and the lower connector assembly 7. The outer wall of the limiting flange 801 slides along the inner wall of the intermediate connector sleeve 6. The reset spring 1 is disposed between the limiting flange 801 and the lower connector assembly 7.

[0060] In this embodiment, the outer wall of the limiting flange 801 slides and seals with the inner wall of the intermediate joint sleeve 6.

[0061] like Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, a placement groove 203 is provided on the outer wall of the upper connector assembly 2, and the placement groove 203 and the inner wall of the intermediate connector sleeve 6 form a placement cavity for placing the airbag 4.

[0062] The upper connector assembly 2 is provided with an air inlet 204 that connects the outer wall of the upper connector assembly 2 to the airbag 4 in the placement cavity, a first flow channel 205 that connects the placement cavity to the piston cavity 601, a second flow channel 206 that connects the piston cavity 601 to the outer wall of the upper connector assembly 2, and a third flow channel 207 that connects the placement cavity to the second flow channel 206.

[0063] like Figure 1 and Figure 3 As shown, a one-way pressure balance valve 9 is provided in the second flow channel 206, and a one-way air filling valve 10 is provided in the air intake channel 204.

[0064] In this embodiment, the drilling fluid is allowed to flow only from the outer wall of the upper connector assembly 2 to the inside by setting a one-way pressure balancing valve 9, and the gas is allowed to flow only into the air bag 4 by setting a one-way air filling valve 10. As an embodiment of this application, both the one-way pressure balancing valve 9 and the one-way air filling valve 10 include a limiting screw and a spring. A sliding hole is provided on the pipe wall at the corner position of the second flow channel 206 and the air inlet channel 204. The limiting screw is slidably set in the sliding hole, and a spring is provided between the limiting screw and the upper end of the sliding hole. When the spring is in a free state, the nut of the limiting screw blocks the flow channel or air passage.

[0065] like Figure 1 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the outer wall of the intermediate joint sleeve 6 is provided with a third liquid inlet 602 that communicates with the piston cavity 601, and the third liquid inlet 602 is located at the lower part of the piston cavity 601.

[0066] In this embodiment, there are four third inlets 602. The four third inlets 602 are arranged in a ring array on the outer wall of the intermediate joint sleeve 6 at the lower part of the piston chamber 601. Drilling fluid can enter or exit the piston chamber 601 through the third inlets 602.

[0067] like Figure 1 , Figure 3 and Figure 7As shown, O-rings 11 are provided between the upper connector assembly 2 and the flow control upper sleeve 3, and between the lower connector assembly 7 and the flow control lower sleeve 8.

[0068] In this embodiment, both the upper connector assembly 2 and the lower connector assembly 7 have annular grooves machined on their inner rings for installing O-ring seals.

[0069] like Figure 8 , Figure 9 and Figure 10 The diagram shows the three operating procedures of the flow control device when well leakage occurs.

[0070] like Figure 8 As shown, when drilling is in normal operation, the entire drilling fluid circulation is equivalent to a closed system. Under the pressure of the annular hydrostatic column, the one-way pressure balance valve 9 opens, and the drilling fluid enters the flow control device from the valve port of the one-way pressure balance valve (on the outer wall of the upper connector assembly 2). It then passes through the second flow channel 206 and the third flow channel 207 in sequence and enters the placement chamber where the airbag 4 is located. Similarly, the drilling fluid enters the piston chamber 601 from the third holes 602 in four directions on the side of the intermediate connector assembly 2. Under the pressure of the drilling fluid and the elastic force of the return spring 1, the limit flange 801 remains in the upward position, causing all eight first inlet holes 301 at the top of the flow control upper sleeve 3 to leak out.

[0071] like Figure 9 As shown, when well leakage occurs in the wellbore, drilling fluid seeps into the formation, reducing the annular hydrostatic pressure and creating negative pressure. This causes the drilling fluid in the drill string to be subjected to downward suction, affecting the operation of the MWD (Mechanical, Dynamic, and Drilling) system. At this time, the one-way air valve 10 opens, and gas enters the air bladder 4, causing it to expand. Due to the action of the one-way pressure balance valve 9, the drilling fluid at the air bladder cannot be discharged from the inlet channel. The drilling fluid is squeezed and discharged downward along the first flow channel 205. The return spring 1 in the flow control device is compressed, and the drilling fluid in the piston chamber is discharged from the third fluid hole 602. This causes the upper flow control sleeve 3 and the lower flow control sleeve 8 to move downward, closing the upper four of the eight first fluid inlet holes 301 and changing the size of the drilling fluid flow area.

[0072] like Figure 10 As shown, the airbag 4 is continuously inflated until it reaches its maximum size, until the upper flow control sleeve 3 and the lower flow control sleeve 8 move to their lowest positions, and all eight first fluid inlet holes 301 of the upper flow control sleeve 3 are closed. At this time, the drilling fluid pressure inside the drill string through the flow control device decreases, balancing with the annular pressure, thus reducing the possibility of negative pressure generation and ensuring that the drilling fluid continuously and stably passes through the MWD, thereby achieving stable MWD signal transmission.

[0073] This application controls the vertical movement of the sliding flow control component in the flow control device by expanding the volume of an inflatable bladder. By controlling the number of first inlet holes 301 connected to the second inlet hole 202, the cross-sectional area of ​​the flow channel is changed. In the event of well leakage, the flow control device functions faster and consumes less energy. Its simple structure allows it to withstand high temperature and pressure conditions downhole without failure. The working principle of this flow control device is based on Bernoulli's principle and the continuity equation. When fluid passes through the flow control device, the reduction in the pipe cross-sectional area leads to an increase in flow velocity. At this time, the kinetic energy of the liquid increases, while the total energy remains constant. Therefore, the energy conversion that occurs when the liquid passes through the flow control device manifests as a pressure decrease.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A drilling fluid flow control device for improving the reliability of MWD signals, characterized in that, Includes an outer shell assembly, a sliding flow control component is slidably disposed inside the outer shell assembly, and a return spring (1) is disposed between the sliding flow control component and the outer shell assembly. The outer shell assembly includes an upper connector assembly (2), and the sliding flow control assembly includes a flow control upper sleeve (3). The outer wall of the flow control upper sleeve (3) is provided with a plurality of first liquid inlet holes (301) communicating with its inner hole. When the reset spring (1) is in a free state, the plurality of first liquid inlet holes (301) are all connected to the liquid inlet end of the upper connector assembly (2). An airbag (4) is provided inside the upper connector assembly (2). When the airbag (4) is inflated, the sliding flow control component slides along the inner wall of the outer shell assembly, so that part or all of the first liquid inlet hole (301) is blocked from the liquid inlet end of the upper connector assembly (2). The lower end of the upper connector assembly (2) is provided with a first sliding hole (201) along the axial direction, and the upper end of the upper connector assembly (2) is provided with a second liquid inlet hole (202) along the axial direction; the first sliding hole (201) and the second liquid inlet hole (202) are connected, the diameter of the second liquid inlet hole (202) is larger than the diameter of the first sliding hole (201), the flow control upper sleeve (3) is slidably disposed in the first sliding hole (201), and when the reset spring (1) is in a free state, several of the first liquid inlets (301) are connected to the second liquid inlet hole (202); The outer casing assembly also includes an intermediate connector sleeve (6) and a lower connector assembly (7); one end of the intermediate connector sleeve (6) is connected to the outer wall of the middle part of the upper connector assembly (2), and the other end of the intermediate connector sleeve (6) is connected to one end of the lower connector assembly (7). The lower connector assembly (7) is provided with a second sliding hole (701) along the axial direction. The lower end of the upper flow control sleeve (3) is connected to the lower flow control sleeve (8), which is slidably disposed in the second sliding hole (701); the upper end of the lower flow control sleeve (8) is provided with a limiting flange (801), which is located in the piston cavity (601) between the upper connector assembly (2) and the lower connector assembly (7), and the outer wall of the limiting flange (801) slides along the inner wall of the intermediate connector sleeve (6). The reset spring (1) is disposed between the limiting flange (801) and the lower connector assembly (7). The upper connector assembly (2) has a placement groove (203) on its outer wall, and the placement groove (203) and the inner wall of the intermediate connector sleeve (6) form a placement cavity for placing the airbag (4); the upper connector assembly (2) has an air inlet (204) connecting the outer wall of the upper connector assembly (2) and the airbag (4) in the placement cavity, a first flow channel (205) connecting the placement cavity and the piston cavity (601), a second flow channel (206) connecting the piston cavity (601) and the outer wall of the upper connector assembly (2), and a third flow channel (207) connecting the placement cavity and the second flow channel (206). A one-way pressure balance valve (9) is provided in the second flow channel (206), and a one-way air charging valve (10) is provided in the air inlet channel (204); a third liquid inlet (602) communicating with the piston chamber (601) is provided on the outer wall of the intermediate joint sleeve (6), and the third liquid inlet (602) is located at the lower part of the piston chamber (601).

2. The drilling fluid flow control device for improving the reliability of MWD signals according to claim 1, characterized in that, The upper end of the flow control upper sleeve (3) is connected to the limit sleeve (5). The outer diameter of the limiting sleeve (5) is greater than the outer diameter of the flow control upper sleeve (3), and the inner diameter of the limiting sleeve (5) is less than the inner diameter of the flow control upper sleeve (3).

3. The drilling fluid flow control device for improving the reliability of MWD signals according to claim 1, characterized in that, A plurality of the first liquid inlet holes (301) are arranged in an annular array on multiple annular planes in the axial direction of the flow control upper sleeve (3).

4. The drilling fluid flow control device for improving the reliability of MWD signals according to claim 1, characterized in that, O-rings (11) are provided between the upper connector assembly (2) and the flow control upper sleeve (3) and between the lower connector assembly (7) and the flow control lower sleeve (8).

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