Dynamic and static liquid level monitoring device suitable for return-loss leakage well

Abstract

The utility model discloses a dynamic and static liquid level monitoring device suitable for a return-free leakage well, which belongs to the technical field of oil and gas well drilling leakage stoppage and comprises a dynamic and static liquid level monitor assembly and a three-way flow choking device, the three-way flow choking device comprises a main monitoring pipe and a side return blowing pipe, and the side return blowing pipe is fixed on the main monitoring pipe to form a three-way structure. The dynamic and static liquid level monitor assembly is fixed to the top end of the main monitoring pipe, the bottom end of the main monitoring pipe is used for being connected with a kill manifold, the end of the side back-blowing pipe is connected with an external blowing mechanism, the main monitoring pipe is provided with a first valve and a second valve, the side back-blowing pipe is provided with a third valve, and by controlling opening and closing of the three valves, the dynamic and static liquid level can be monitored. The liquid level monitoring device can monitor the liquid level of the return-loss leakage well, cleans the three-way flow choking device through the external blowing mechanism, solves the technical problem that a liquid level monitoring instrument in the prior art is prone to being blocked, achieves convenient and efficient use of the dynamic and static liquid level monitoring device, and provides a convenient and efficient solution for well drilling leakage stoppage operation.

Description

Technical Field

[0001] The utility model belongs to the technical field of leak plugging in oil and natural gas drilling, and in particular relates to a dynamic and static liquid level monitoring device suitable for a lost-return well. Background Art

[0002] Lost circulation is an inevitable downhole complication during drilling. It can be categorized by type of loss, which can be divided into lost-return and non-lost-return wells. Over 300 lost-return wells occur annually in the Changqing drilling area, of which over 60% are lost-return wells. The drilling fluid level in these lost-return wells cannot be observed, making it impossible to determine the internal wellbore pressure during plugging. This results in an extremely low first-time plugging success rate and significantly increases plugging costs. Therefore, the mature ultrasonic fluid level monitor has become an effective technical tool for lost-return wells.

[0003] For example, Chinese patent document CN117927167A discloses a system and method for monitoring liquid injection for oil and gas field well repair operations. In its monitoring system, the wellhead monitoring unit includes a wellhead sounding module and a sound wave acquisition module, both of which are arranged at the wellhead pressure valve of the wellbore. The signal output end of the wellhead sounding module and the signal output end of the sound wave acquisition module are directly connected to the signal input end of the controller. During drilling operations, the measuring instrument is in direct contact with fluids such as drilling fluid and returned mud, especially when fluids such as drilling fluid and returned mud are retained for a long time, which may cause the measuring instrument to be blocked, thereby ultimately affecting the normal operation of the liquid level monitor.

[0004] To this end, it is urgent to design a new device that cooperates with the liquid level monitor to monitor the liquid level downhole, so as to assist the normal operation of the monitor conveniently, stably and efficiently, overcome the technical problem that the existing liquid level monitoring instrument is prone to blockage, and ensure that the drilling operation can proceed smoothly. Utility Model Content

[0005] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art and provide a dynamic and static liquid level monitoring device suitable for lost return wells. The utility model effectively solves the technical problem that the liquid level monitoring instrument in the prior art is easily blocked through the connection structure of the dynamic and static liquid level monitoring instrument assembly and the three-way flow blocking device, and the opening and closing control of the first valve, the second valve and the third valve, realizes the convenient and efficient use of the dynamic and static liquid level monitoring device, and provides a convenient and efficient solution for drilling plugging operations.

[0006] In order to achieve the above purpose, the technical solution adopted by the present utility model is as follows:

[0007] The utility model discloses a dynamic and static liquid level monitoring device suitable for a lost-return well, comprising a dynamic and static liquid level monitor assembly and a three-way flow blocking device, wherein the three-way flow blocking device comprises a main monitoring pipe and a side return blow pipe, the side return blow pipe is fixed on the main monitoring pipe and forms a three-way structure, the dynamic and static liquid level monitor assembly is fixed on the top end of the main monitoring pipe, the bottom end of the main monitoring pipe is used to be connected to the well-killing manifold, the end of the side return blow pipe is connected to an external blowing mechanism, the main monitoring pipe is respectively provided with a first valve and a second valve, and the side return blow pipe is provided with a third valve, the dynamic and static liquid level monitor assembly can monitor the liquid level of the lost-return well by controlling the opening and closing of the first valve, the second valve and the third valve, and the external blowing mechanism can clean the three-way flow blocking device by controlling the opening and closing of the first valve, the second valve and the third valve.

[0008] The dynamic and static liquid level monitor assembly can monitor the liquid level of the lost return well by connecting to the well killing manifold through the main monitoring pipe when the third valve is closed and the first valve and the second valve are opened at the same time.

[0009] When the first valve is closed and the second valve and the third valve are opened at the same time, the external air blowing mechanism can form a return blowing channel through the side return blowing pipe and the main monitoring pipe to clean the three-way flow blocking device.

[0010] The dynamic and static liquid level monitor assembly includes an ultrasonic data processing system and an ultrasonic emitting gun. The ultrasonic emitting gun is connected to the ultrasonic data processing system via a sensor line, and the ultrasonic emitting gun is connected to the top of the main monitoring tube.

[0011] The ultrasonic emitting gun is connected to a high-pressure gas source through an air pipeline, and the pressure range provided by the high-pressure gas source is within 5-8 MPa.

[0012] The top and bottom ends of the main monitoring pipe are respectively provided with a first threaded male buckle and a second threaded male buckle. The top end of the main monitoring pipe is threadedly connected to the ultrasonic transmitting gun through the first threaded male buckle, and the bottom end of the main monitoring pipe is threadedly connected to the back-blow interface provided on the well-killing manifold through the second threaded male buckle.

[0013] The end of the side return blow pipe is provided with a third threaded male buckle, and the end of the side return blow pipe is threadedly connected to the external blowing mechanism through the third threaded male buckle.

[0014] The main monitoring pipe is arranged vertically, and the side return blow pipe is horizontally welded to the middle of the main monitoring pipe.

[0015] The ratio of the outer diameter and wall thickness of the main monitoring pipe is 10:1, the ratio of the outer diameter and wall thickness of the side return blow pipe is 10:1, and the length of the main monitoring pipe is ≤300mm.

[0016] The opening positions of the first valve and the second valve are parallel to the axis of the main monitoring pipe, and the opening position of the third valve is parallel to the axis of the side return blow pipe.

[0017] The advantages of adopting the utility model are:

[0018] 1. In the present invention, firstly, a three-way structure is formed by the main monitoring pipe and the side return blow pipe, and a dynamic and static liquid level monitor assembly is installed at the top of the main monitoring pipe, and the bottom end is connected to the well killing manifold. This connection structure design clarifies the installation layout of the dynamic and static liquid level monitor assembly, ensuring that the dynamic and static liquid level monitor device can smoothly carry out normal monitoring of the downhole liquid level without changing the integrity of the drilling site equipment. It not only maintains the continuity and smoothness of the drilling operation, but also adapts to various working conditions that may occur during the drilling process.

[0019] Secondly, by installing the dynamic and static liquid level monitor assembly at the top of the main monitoring pipe and coordinating the opening and closing of the first, second, and third valves, the present invention achieves a one-time installation and long-term use effect compared to the prior art represented by Chinese Patent Document No. CN117927167A. This eliminates damage to the connection parts of the dynamic and static liquid level monitor assembly caused by repeated disassembly, thereby improving the stability and durability of the present invention. When monitoring operations are not required, closing the first and / or second valves prevents fluids such as drilling fluid from clogging the monitor assembly, thereby extending the service life of the dynamic and static liquid level monitor device.

[0020] Finally, by setting the first valve, the second valve and the third valve, and the design of connecting the end of the side return blow pipe to the external blowing mechanism, the technical problem of the liquid level monitoring instrument in the existing technology being easily blocked is effectively solved. The dynamic and static liquid level monitoring instrument assembly can monitor the liquid level of the lost-return well by controlling the opening and closing of the first valve, the second valve and the third valve. The external blowing mechanism can clean the three-way flow blocking device by controlling the opening and closing of the first valve, the second valve and the third valve, which significantly improves the convenience, efficiency, stability and durability of the dynamic and static liquid level monitoring device.

[0021] 2. In the present invention, by closing the third valve, the accuracy and stability of the downhole liquid level monitoring data caused by external factors are effectively prevented. At the same time, by opening the first valve and the second valve, the dynamic and static liquid level monitor assembly can accurately receive the liquid level information from the downhole, thereby performing accurate monitoring and analysis.

[0022] 3. In the present invention, by closing the first valve and opening the second valve and the third valve, the side return blow pipe and the main monitoring pipe form a return blow channel, so that the external blowing mechanism can effectively remove residual drilling fluid, mud and other fluids attached to the inner walls of the main monitoring pipe and the side return blow pipe through the return blow channel. This design not only facilitates the daily cleaning and maintenance of the three-way flow-blocking device, but also further extends the service life of the dynamic and static liquid level monitoring device and improves its monitoring accuracy.

[0023] 4. The utility model adopts a dynamic and static liquid level monitor component consisting of an ultrasonic transmitting gun and an ultrasonic data processing system, and combines the connection structure of the ultrasonic transmitting gun and the main monitoring pipe to ensure the efficiency and accuracy of liquid level monitoring in lost return wells.

[0024] 5. In the present invention, the ultrasonic transmitting gun is connected to the high-pressure gas source through the gas pipeline, and the pressure range provided by the high-pressure gas source is set to within 5-8MPa, ensuring its normal operation under high-pressure environment, thereby ensuring the stable operation of the dynamic and static liquid level monitoring device in the high-pressure well.

[0025] 6. In the present invention, the first and second threaded male buckles are respectively designed at the top and bottom ends of the main monitoring tube, and the third threaded male buckle is designed at the end of the side return blow pipe, thereby ensuring the convenience of installation and disassembly of the ultrasonic transmitting gun, the return blow interface on the well-killing manifold, the external blowing mechanism and the dynamic and static liquid level monitoring device.

[0026] 7. In the present invention, by setting the ratio of the outer diameter and the wall thickness of the main monitoring tube to 10:1 and the ratio of the outer diameter and the wall thickness of the side return blow pipe to 10:1, it is ensured that the main monitoring tube and the side return blow pipe have sufficient structural strength to withstand higher internal pressure, thereby ensuring the long-term stability and reliability of the dynamic and static liquid level monitoring device; in addition, by setting the length of the main monitoring tube to ≤300mm, the convenience of on-site operation is improved.

[0027] 8. In the present invention, the convenience of on-site operation is further optimized by designing that the opening positions of the main first valve and the second valve are parallel to the axis of the main monitoring pipe, and the opening position of the third valve is parallel to the axis of the side return blowpipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the overall installation of the utility model;

[0029] Figure 2 It is a structural diagram of the three-way flow blocking device in the utility model.

[0030] The numbers in the figure are: 1. Dynamic and static liquid level monitor assembly, 2. High-pressure gas source, 3. Three-way flow blocking device, 30. Main monitoring pipe, 31. Side return blow pipe, 33. First threaded male buckle, 34. Second threaded male buckle, 35. Third threaded male buckle, 4. Well killing manifold, 5. Ultrasonic transmitting gun, 6. Return blow interface, 7. First valve, 8. External blowing mechanism, 9. Ultrasonic data processing system, 10. Second valve, 11. Third valve. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. For ease of description, the relative positional relationships of the various components are described based on the layout of the drawings in the specification. For example, the positional relationships of front, back, up, down, left, right, top, and bottom are determined based on the layout directions of the drawings in the specification.

[0032] Example 1

[0033] A dynamic and static liquid level monitoring device suitable for lost return wells, such as Figure 1-2 As shown, it includes a dynamic and static liquid level monitor assembly 1 and a three-way flow blocking device 3. The three-way flow blocking device 3 includes a main monitoring pipe 30 and a side return blow pipe 31. The side return blow pipe 31 is fixed on the main monitoring pipe 30 and forms a three-way structure. Figure 1 Taking the direction shown as an example, the dynamic and static liquid level monitor assembly 1 is fixed to the top of the main monitoring pipe 30, and the bottom end of the main monitoring pipe 30 is used to connect with the well killing manifold 4, and is connected to the wellbore of the lost return well through the well killing manifold 4; the end of the side return blow pipe 31 is connected to the external blowing mechanism 8 to Figure 1 Taking the direction shown as an example, the external blowing mechanism 8 is connected to the right end of the side return blowing pipe 31 , and the left end of the side return blowing pipe 31 is connected to the main monitoring pipe 30 .

[0034] like Figure 2 As shown, the main monitoring pipe 30 is provided with a first valve 7 and a second valve 10, respectively, and the side return blow pipe 31 is provided with a third valve 11. The first valve 7, the second valve 10, and the third valve 11 are all high-pressure valves. The first valve 7 and the second valve 10 are opened parallel to the axis of the main monitoring pipe 30, and the third valve 11 is opened parallel to the axis of the side return blow pipe 31. The dynamic and static liquid level monitor assembly 1 can monitor the liquid level in a loss-of-return well by controlling the opening and closing of the first valve 7, the second valve 10, and the third valve 11. The external air blowing mechanism 8 can clean the three-way flow blocking device 3 by controlling the opening and closing of the first valve 7, the second valve 10, and the third valve 11.

[0035] Furthermore, when the third valve 11 is closed and the first and second valves 7, 10 are simultaneously open, the dynamic and static liquid level monitor assembly 1 can monitor the liquid level of the lost-return well through the main monitoring pipe 30 connected to the kill manifold 4. Specifically, closing the third valve 11 effectively prevents interference from external factors, ensuring the accuracy and stability of the monitoring data. At the same time, the connection between the main monitoring pipe 30 and the kill manifold 4 enables the dynamic and static liquid level monitor assembly 1 to accurately receive liquid level information from the wellbore of the lost-return well, thereby achieving accurate monitoring and in-depth analysis of the liquid level.

[0036] Furthermore, when the first valve 7 is closed and the second and third valves 10 and 11 are simultaneously opened, the external air blowing mechanism 8 can form a return blow channel through the side return blow pipe 31 and the main monitoring pipe 30 to clean the three-way flow blocking device 3. At this time, the connection between the dynamic and static liquid level monitoring instrument assembly 1 and the wellbore of the wellbore of the lost return well is blocked. The cleaning action of the external air blowing mechanism 8 effectively removes residual drilling fluid, mud, and other fluids adhering to and accumulating on the inner walls of the main monitoring pipe 30 and the side return blow pipe 31.

[0037] When the first valve 7, the second valve 10 and the third valve 11 are closed at the same time, or when only the second valve 10 is closed, the main monitoring pipe 30 protects the dynamic and static liquid level monitor assembly 1 by blocking the connection with the wellbore manifold 4, thereby preventing the drilling fluid, mud and other fluids in the wellbore from flowing back through the three-way flow blocking device 3 to the dynamic and static liquid level monitor assembly 1 to form a blockage, thereby affecting the normal monitoring operation of the dynamic and static liquid level monitoring device of the present invention.

[0038] Furthermore, the dynamic and static liquid level monitor assembly 1 includes an ultrasonic data processing system 9 and an ultrasonic transmitting gun 5 . The ultrasonic transmitting gun 5 is connected to the ultrasonic data processing system 9 via a sensor line, and the ultrasonic transmitting gun 5 is connected to the top of the main monitoring tube 30 .

[0039] The ultrasonic emitting gun 5 is connected to a high-pressure gas source 2 via an air pipeline. The pressure range provided by the high-pressure gas source 2 is within 5-8 MPa. The high-pressure gas source 2 usually uses nitrogen as the gas source medium. In addition, the three-way flow blocking device 3 can withstand a pressure of ≤10 MPa.

[0040] like Figure 1-2 As shown, the top and bottom ends of the main monitoring pipe 30 are respectively provided with a first threaded pin 33 and a second threaded pin 34. The top end of the main monitoring pipe 30 is threadedly connected to the ultrasonic transmitting gun 5 through the first threaded pin 33, and the bottom end of the main monitoring pipe 30 is threadedly connected to the back-blow interface 6 provided on the well-killing manifold 4 through the second threaded pin 34.

[0041] The blowback port 6 of the kill manifold 4 is actually a threaded port of the kill manifold 4, which can be blocked with a plug wire at ordinary times. When the kill manifold 4 pipe needs to be cleaned, the plug wire is opened and the air line is used to inflate the pipe for cleaning. Since this is a technique known to those skilled in the art, it will not be described in detail here.

[0042] The end of the side return blowpipe 31 (with Figure 2 Taking the direction shown as an example, the end portion is the right end of the side return blow pipe 31 ) is provided with a third threaded male buckle 35 , and the end portion of the side return blow pipe 31 is threadedly connected to the external blowing mechanism 8 through the third threaded male buckle 35 .

[0043] The main monitoring tube 30 and the side return blow pipe 31 are preferably made of stainless steel. The main monitoring tube 30 is vertically arranged, and the left end of the side return blow pipe 31 is horizontally welded to the middle of the main monitoring tube 30 .

[0044] The ratio of the outer diameter to the wall thickness of the main monitoring pipe 30 is 10:1, and the ratio of the outer diameter to the wall thickness of the side return blow pipe 31 is 10:1. In order to facilitate on-site operation, the length of the main monitoring pipe 30 is ≤300mm.

[0045] The working process of the utility model when in use is as follows:

[0046] 1. Installation and preparation stage:

[0047] Install the dynamic and static liquid level monitor assembly 1 on the three-way flow blocking device 3, turn on the ultrasonic data processing system 9 to ensure that it is in working condition, and then turn on the high-pressure gas source 2 to provide the required high-pressure gas for the ultrasonic emission gun 5.

[0048] 2. Preparation for monitoring operation and valve adjustment:

[0049] Close the third valve 11 to ensure that the side return blowpipe 31 does not participate in the fluid flow during the wellbore liquid level monitoring process. Then, open the first valve 7 and the second valve 10 to create a path for the transmission and reception of ultrasonic waves.

[0050] 3. Ultrasonic emission and data processing:

[0051] The ultrasonic transmitter 5 is started to emit ultrasonic waves into the wellbore. The ultrasonic data processing system 9 receives the ultrasonic signal returned from the wellbore. This process usually takes 1-3 seconds. The received ultrasonic signal is processed by software to determine the position of the liquid level in the wellbore. From the beginning of monitoring to the end, the entire process generally takes 2-3 minutes.

[0052] 4. Maintenance and cleaning:

[0053] After the monitoring operation is completed, the first valve 7 is closed to prevent the drilling fluid from entering the three-way flow blocking device 3 and then blocking the dynamic and static liquid level monitor assembly 1.

[0054] At the same time, the second valve 10 and the third valve 11 can be opened to connect the side return blow pipe 31 with the external blowing mechanism 8. Then, the external blowing mechanism 8 is started to blow gas into the main monitoring pipe 30 through the side return blow pipe 31 to prevent blockage and keep it unobstructed.

[0055] 5. End and standby:

[0056] The second valve 10 and the third valve 11 can be closed to put the three-way flow blocking device 3 into a closed state, ready for next use.

[0057] Example 2

[0058] Based on the structural design of Example 1, this example illustrates the practical application of the present invention in a lost-return well scenario.

[0059] For example, Well Qiao XX-2, a horizontal oil exploration well, experienced a loss of return during its second drilling phase to a depth of 703 m, rendering the fluid level unobservable at the wellhead. To accurately monitor the downhole fluid level, the device designed and constructed as described in Examples 1-3 was employed for downhole fluid level monitoring and leak plugging.

[0060] First, the operator turned on the ultrasonic data processing system 9 and simultaneously activated the high-pressure gas source 2, injecting 6 MPa of high-pressure gas into the ultrasonic transmitter 5. Next, the operator closed the third valve 11 and simultaneously opened the first valve 7 and the second valve 10. The ultrasonic transmitter 5 was then activated, emitting ultrasonic waves downhole. Two seconds later, the ultrasonic data processing system 9 successfully received the return ultrasonic signal and, through the system's software, determined the specific location of the wellbore liquid level to be 320 meters. The entire monitoring process, from start to finish, took only two minutes.

[0061] After determining the specific position of the liquid level in the wellbore, plugging construction was immediately started at the bottom of the well. Curable plugging slurry was injected through the drill pipe, and dynamic monitoring showed that the liquid level in the wellbore continued to rise. Finally, the liquid level successfully returned to the wellhead.

[0062] However, during the construction process, the wellbore pressure exceeded the formation's bearing capacity, and the wellbore fluid level fell below the ground. The dynamic and static fluid level monitor assembly 1 detected that the fluid level in the wellbore was within the range of 50-60m. In response to this situation, operators began implementing the following plugging process: a plan was designed to reserve 100m of curable plugging slurry in the wellbore. Therefore, 160-170m of drilling fluid was injected into the annulus to ensure that 100m of curable plugging slurry was reserved in the wellbore, thereby improving the success rate of plugging. After 12 hours of waiting, the curable plugging slurry had solidified. Later, a sweeping operation was carried out and drilling resumed, with the plugging section length being 102m.

[0063] After the plugging operation is completed, the operator closes the first valve 7, opens the third valve 11, connects the external air blowing mechanism 8, and performs a back-blowing operation on the three-way flow-blocking device 3 to remove residual drilling fluid, mud, and other fluids inside. Subsequently, the first valve and / or the second valve 10 are closed, sealing the three-way flow-blocking body 3 and protecting the dynamic and static liquid level monitor assembly 1 until the next use.

[0064] Subsequently, the well experienced loss of return when drilling to 1200m and 2600m. However, the structural design of the utility model and the use of the aforementioned plugging process effectively ensured that the wellbore could be plugged with solidified plugging slurry, achieving successful plugging in one go.

[0065] The structural design of this utility model has demonstrated extremely high efficiency and success rates in field applications. In a case of 30 wells, each well required only a single installation for long-term use. The applicant's actual testing confirmed that this design effectively ensured leak plugging in each well, increasing the first-pass plugging success rate by 30.5%, significantly reducing plugging costs and improving efficiency.

[0066] The above description is only a specific embodiment of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all disclosed features, or all steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A dynamic and static liquid level monitoring device suitable for lost return wells, characterized by: The invention comprises a dynamic and static liquid level monitor assembly (1) and a three-way flow blocking device (3), wherein the three-way flow blocking device (3) comprises a main monitoring pipe (30) and a side return blow pipe (31), wherein the side return blow pipe (31) is fixed on the main monitoring pipe (30) and forms a three-way structure, wherein the dynamic and static liquid level monitor assembly (1) is fixed on the top end of the main monitoring pipe (30), wherein the bottom end of the main monitoring pipe (30) is used for connecting to a well-killing manifold (4), and an end of the side return blow pipe (31) is connected to an external air blowing mechanism (8); The main monitoring pipe (30) is provided with a first valve (7) and a second valve (10), respectively, and the side return blow pipe (31) is provided with a third valve (11). The dynamic and static liquid level monitor assembly (1) can monitor the liquid level of the lost return well by controlling the opening and closing of the first valve (7), the second valve (10) and the third valve (11). The external blowing mechanism (8) can clean the three-way flow blocking device (3) by controlling the opening and closing of the first valve (7), the second valve (10) and the third valve (11).

2. The dynamic and static liquid level monitoring device for a lost circulation well according to claim 1, characterized in that: The dynamic and static liquid level monitor assembly (1) can monitor the liquid level of the lost return well by connecting to the well-killing manifold (4) through the main monitoring pipe (30) when the third valve (11) is closed and the first valve (7) and the second valve (10) are opened at the same time.

3. The dynamic and static liquid level monitoring device for a lost-return well according to claim 1, characterized in that: When the first valve (7) is closed and the second valve (10) and the third valve (11) are opened simultaneously, the external air blowing mechanism (8) can clean the three-way flow blocking device (3) by forming a return blowing channel through the side return blowing pipe (31) and the main monitoring pipe (30).

4. The dynamic and static liquid level monitoring device for a lost-return well according to claim 1, characterized in that: The dynamic and static liquid level monitor assembly (1) comprises an ultrasonic data processing system (9) and an ultrasonic emitting gun (5), wherein the ultrasonic emitting gun (5) is connected to the ultrasonic data processing system (9) via a sensor line, and the ultrasonic emitting gun (5) is connected to the top end of the main monitoring tube (30).

5. The dynamic and static liquid level monitoring device for a lost-return well according to claim 4, characterized in that: The ultrasonic emission gun (5) is connected to a high-pressure gas source (2) via an air pipeline. The pressure range provided by the high-pressure gas source (2) is within 5-8 MPa.

6. The dynamic and static liquid level monitoring device for a lost-return well according to claim 5, characterized in that: The top and bottom ends of the main monitoring pipe (30) are respectively provided with a first threaded male buckle (33) and a second threaded male buckle (34); the top end of the main monitoring pipe (30) is threadedly connected to the ultrasonic transmitting gun (5) via the first threaded male buckle (33); and the bottom end of the main monitoring pipe (30) is threadedly connected to a blowback interface (6) provided on the well killing manifold (4) via the second threaded male buckle (34).

7. The dynamic and static liquid level monitoring device for a lost-return well according to claim 6, characterized in that: The end of the side return blow pipe (31) is provided with a third threaded male buckle (35), and the end of the side return blow pipe (31) is threadedly connected to the external blowing mechanism (8) via the third threaded male buckle (35).

8. The dynamic and static liquid level monitoring device for lost return wells according to claim 7, characterized in that: The main monitoring pipe (30) is arranged vertically, and the side return blow pipe (31) is welded transversely to the middle of the main monitoring pipe (30).

9. The dynamic and static liquid level monitoring device for a lost-return well according to claim 8, characterized in that: The ratio of the outer diameter of the main monitoring pipe (30) to the wall thickness is 10:1, the ratio of the outer diameter of the side return blow pipe (31) to the wall thickness is 10:1, and the length of the main monitoring pipe (30) is ≤300 mm.

10. A dynamic and static liquid level monitoring device for a lost circulation well according to any one of claims 1 to 9, characterized in that: The opening positions of the first valve (7) and the second valve (10) are parallel to the axis of the main monitoring pipe (30), and the opening position of the third valve (11) is parallel to the axis of the side return blow pipe (31).

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