A ground throttling device

Abstract

This application provides a surface throttling device, including a throttling device body. The throttling device body throttles and reduces the pressure of natural gas flowing through it, ensuring that the temperature of the natural gas remains above the critical temperature for natural gas hydrates. The throttling device body includes multiple orifice plates spaced at predetermined intervals, each orifice plate having a throttling orifice. This allows high-pressure natural gas from the wellhead to reach low-pressure export pipelines without generating natural gas hydrates after passing through the surface throttling device. The operation is simple, low-cost, and simplifies the natural gas well site gathering and transportation process.

Description

Technical Field

[0001] The present application relates to the technical field of natural gas throttling, gathering and transportation, and in particular to a ground throttling device. Background Art

[0002] Natural gas hydrate is a crystalline complex formed by water and hydrocarbon gas in natural gas under certain pressure and temperature (higher than the freezing point of water). There is a maximum temperature for the formation of natural gas hydrate, namely the critical temperature. If this temperature is exceeded, hydrate will not form even at high pressure. The formation of hydrate will block the wellbore or gas production pipeline, affecting the normal production of the gas well.

[0003] In the process of gas field production, according to the characteristics of the ground development mode, the pressure reduction production method is often adopted. In the pressure reduction production, hydrates may be formed in the wellbore and the surface throttling process, causing pipeline blockage and bringing serious harm to gas well production.

[0004] Commonly used methods for preventing and controlling hydrates include: downhole throttling technology, antifreeze injection method, and ground heating method.

[0005] The downhole throttling process is to place the downhole throttling device at an appropriate position of the production tubing to achieve throttling and pressure reduction in the wellbore, transfer the ground throttling process to the wellbore, make full use of geothermal heating, make the temperature of the gas flow after throttling higher than the maximum temperature for hydrate formation under the pressure conditions after throttling, and bury the ground gas gathering pipeline under the permafrost layer at the same time, so that hydrate blockage will not form in the wellbore, wellhead and ground pipeline.

[0006] The existing problems are: the throttle is below the formation, the operation and salvage costs are high, and underground data collection is inconvenient, making it difficult to truly understand the underground gas production parameters.

[0007] The antifreeze injection method refers to the injection of methanol antifreeze during the production and operation of some gas wells and gas gathering pipelines to lower the temperature point of hydrate formation and achieve the purpose of preventing hydrate formation.

[0008] The problem is that methanol antifreeze itself is relatively expensive, and additional methanol injection equipment and operating pipelines are required.

[0009] The ground heating throttling process adds a heating furnace on the ground, first heats the medium to a certain temperature, and then uses a throttling valve to throttle. The temperature drop caused by throttling is compensated by heating.

[0010] The problem is that the heating furnace has high operating costs and requires constant maintenance.

[0011] Therefore, a throttling process is needed to solve the problems of difficult and high cost operation of downhole throttling devices, and can also replace the heating furnace and throttling valve of ground throttling, and can also replace the alcohol injection device to simplify the natural gas well field gathering and transportation process. Summary of the invention

[0012] The purpose of the present application is to overcome the defects of the prior art and provide a ground throttling device.

[0013] To achieve the above purpose, this application adopts the following technical solutions:

[0014] A ground throttling device comprises a throttling device body, wherein the throttling device body throttles and reduces the pressure of natural gas flowing through the throttling device body and ensures that the temperature of the natural gas is always above the critical temperature of natural gas hydrate, wherein the throttling device body comprises a plurality of throttling orifice plates, the throttling orifice plates are arranged at a predetermined distance, and a throttling hole is provided on each of the throttling orifice plates.

[0015] Optionally, the ground throttling device further includes: a ball valve, a first pressure gauge, a first thermometer, a second pressure gauge, a second thermometer, and a flow meter, wherein:

[0016] The input end of the ball valve is used to connect with the wellhead natural gas to obtain natural gas, the output end of the ball valve is connected to the input end of the first pressure gauge through a pipeline, the output end of the first pressure gauge is connected to the input end of the first thermometer, the output end of the first thermometer is connected to the input end of the throttling device body, the output end of the throttling device body is connected to the input end of the second pressure gauge, the output end of the second pressure gauge is connected to the input end of the second thermometer, the output end of the second thermometer is connected to the input end of the flow meter, and the output end of the flow meter is used to connect to a low-pressure external transmission pipeline to output the reduced-pressure natural gas.

[0017] Optionally, the ground throttling device further includes: a ball valve, a first pressure gauge, a first thermometer, a second pressure gauge, a second thermometer, and a flow meter, wherein:

[0018] The input end of the ball valve is used to connect with the wellhead natural gas to obtain natural gas, the output end of the ball valve is connected to the input end of the first thermometer through a pipeline, the output end of the first thermometer is connected to the input end of the first pressure gauge, the output end of the first pressure gauge is connected to the input end of the throttling device body, the output end of the throttling device body is connected to the input end of the second thermometer, the output end of the second thermometer is connected to the input end of the second pressure gauge, the output end of the second pressure gauge is connected to the input end of the flow meter, and the output end of the flow meter is used to connect to a low-pressure external transmission pipeline to output the reduced-pressure natural gas.

[0019] Optionally, the diameter of the throttling hole gradually decreases along the throttling direction of the throttling device body.

[0020] Optionally, each throttling orifice plate in the throttling device body has a different aperture size, and the aperture size is determined so that no hydrate is formed at the throttling hole of each throttling orifice plate and no blocked flow is formed.

[0021] Optionally, the width of the orifice of each throttling orifice in the throttling device body close to the side wall of the pipeline is greater than the width of the orifice at the throttling hole end.

[0022] Optionally, each throttling orifice plate in the throttling device body is arranged in a pipeline in the ground throttling device through a flange connection.

[0023] Optionally, the ground throttling device is provided with a thermal insulation layer.

[0024] The ground throttling device of the present application throttles and reduces the pressure of the natural gas flowing through the throttling device body through the throttling device body, and ensures that the temperature of the natural gas is always above the critical temperature of natural gas hydrates, so that the high-pressure natural gas at the natural gas wellhead reaches the throttling after passing through the ground throttling device while ensuring that the temperature is not lower than the natural gas hydrate formation temperature and reaches the low-pressure external transmission pipeline without generating natural gas hydrates. The operation is simple, the cost is low, and the natural gas well site gathering and transportation process is simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the well site throttling system of an embodiment of the present application;

[0026] Figure 2 It is a structural schematic diagram of a surface throttling device in a well site throttling system in an embodiment of the present application;

[0027] Figure 3 It is a schematic diagram of the diffusion section between the throttling orifice plates in the ground throttling device;

[0028] Figure 4 is a schematic diagram of the mass flow average temperature distribution diagram of the axial cross section of the multi-stage orifice plate;

[0029] Figure 5 is a schematic diagram of a pressure distribution diagram of an axial cross section of a multi-stage orifice plate;

[0030] Figure 6 yes Figure 2 Schematic diagram of the geometric model of the multi-stage orifice plate in the ground throttling device;

[0031] Figure 7 is a schematic diagram of a geometric model of each orifice plate in a multi-stage orifice plate of an embodiment of the present application;

[0032] Figure 8 It is a flow chart of the well site throttling method according to an embodiment of the present application.

[0033] Reference numerals

[0034] 101-emergency shut-off valve, 102-ground throttling device, 103-fourth ball valve, 104-first ball valve, 105-flow meter, 106-third ball valve, 107-second ball valve, 108-gas tree, 109-venting pipeline, 110-low-pressure external transmission pipeline, 201-throttling device body, 202-fifth ball valve, 203-first pressure gauge, 204-first thermometer, 205-throttling orifice, 206-throttling orifice, 207-throttling orifice, 208-throttling orifice, 209-second pressure gauge, 210-second thermometer, 211-flow meter. DETAILED DESCRIPTION

[0035] The specific implementation of the present application is described below in conjunction with the accompanying drawings.

[0036] In this document, “upper”, “lower”, “front”, “back”, “left”, “right”, etc. are only used to indicate the relative position relationship between related parts, rather than to limit the absolute positions of these related parts.

[0037] In this article, "first", "second", etc. are only used to distinguish each other, and do not indicate the importance and order, or the premise of each other's existence.

[0038] In this document, “equal”, “same”, etc. are not strictly limited in a mathematical and / or geometric sense, but also include errors that can be understood by those skilled in the art and are allowed in manufacturing or use.

[0039] Unless otherwise stated, the numerical ranges herein include not only the entire range within its two endpoints but also include several sub-ranges contained therein.

[0040] The present application provides a well site throttling system, such as Figure 1 As shown, the well site throttling system includes a gas production tree 108, a ground throttling device 102 and a low-pressure external transmission pipeline 110, wherein the input end of the ground throttling device 102 is connected to the gas production tree 108 through a pipeline, and the output end of the ground throttling device 102 is connected to the low-pressure external transmission pipeline 110 through a pipeline, wherein the ground throttling device 102 includes a throttling device body 201, and the throttling device body 201 throttles and reduces the pressure of the natural gas flowing through the throttling device body 201, and ensures that the temperature of the natural gas is always above the critical temperature of natural gas hydrates.

[0041] Specifically, the input end of the ground throttling device 102 is connected to the gas production tree 108 through a pipeline, and is used to obtain high-pressure natural gas from the natural gas wellhead. The ground throttling device 102 is used to throttle and reduce the pressure of the high-pressure natural gas to obtain low-pressure natural gas that meets transmission requirements or production requirements. The output end of the ground throttling device 102 is connected to the low-pressure export pipeline 110 through a pipeline, and is used to export the low-pressure natural gas to the downstream pipeline.

[0042] Natural gas hydrate refers to a crystalline cage-shaped solid complex formed by the interaction of host molecules (water) and guest molecules (methane, ethane and other hydrocarbon gases, and nitrogen, carbon dioxide and other non-hydrocarbon gas molecules) under low temperature and high pressure conditions through van der Waals forces. The water molecules form a crystalline grid with the help of hydrogen bonds, and the pores in the grid are filled with light hydrocarbons, heavy hydrocarbons or non-hydrocarbon molecules. Hydrates have extremely strong gas storage and carrying capacity. A unit volume of natural gas hydrate can store 160 to 180 times the amount of gas of this volume. The critical temperature of natural gas hydrate is the highest critical temperature for the formation of natural gas hydrates. If this temperature is exceeded, hydrates will not form at any higher pressure. The throttling device body 201 of the ground throttling device 102 throttles and reduces the pressure of the natural gas flowing through the throttling device body 201, and ensures that the temperature of the natural gas is always above the critical temperature.

[0043] The well site throttling system provided in the present application can achieve throttling of high-pressure natural gas at the natural gas wellhead after passing through the ground throttling device while ensuring that the temperature is not lower than the natural gas hydrate formation temperature and reaches the low-pressure external transmission pipeline without producing natural gas hydrates. The operation is simple, the cost is low, and the natural gas well site gathering and transportation process is simplified.

[0044] In one embodiment of the present application, Figure 1 As shown, the well site throttling system also includes: an emergency shut-off valve 101, the input end of the emergency shut-off valve 101 is connected to the gas production tree 108 through a pipeline, and the output end of the emergency shut-off valve 101 is connected to the input end of the ground throttling device 102 through a pipeline; a flow meter 105, the input end of the flow meter 105 is connected to the output end of the ground throttling device 102 through a pipeline, and the output end of the flow meter 105 is connected to the low-pressure external transmission pipeline 110 through a pipeline.

[0045] Specifically, the input end of the emergency shut-off valve 101 is connected to the gas production tree 108 through a pipeline, and is used to obtain high-pressure natural gas from the natural gas wellhead. The output end of the emergency shut-off valve 101 is connected to the input end of the ground throttling device 102 through a pipeline, and is used to be able to cut off in time when an emergency accident or abnormal natural gas pressure occurs, so as to avoid high-pressure natural gas from entering the ground throttling device 102 and causing damage to the device. The flow meter 105 is used to measure the flow passing through.

[0046] In one embodiment of the present application, Figure 1 As shown, the well site throttling system also includes: a first ball valve 104, which is arranged between the ground throttling device 102 and the flow meter 105, the input end of the first ball valve 104 is connected to the output end of the ground throttling device 102 through a pipeline, and the output end of the first ball valve 104 is connected to the input end of the flow meter 105 through a pipeline; a second ball valve 107, which is arranged between the flow meter 105 and the low-pressure external transmission pipeline 110, the input end of the second ball valve 107 is connected to the output end of the flow meter 105 through a pipeline, and the output end of the second ball valve 107 is connected to the low-pressure external transmission pipeline 110 through a pipeline.

[0047] In actual applications, low-pressure natural gas reaches the input end of the first ball valve 104 from the output end of the ground throttling device 102 through a pipeline, reaches the input end of the flow meter 105 from the output end of the first ball valve 104, passes through the flow meter 105, and then reaches the input end of the second ball valve 107 from the output end of the flow meter 105 through a pipeline, and reaches the low-pressure external transmission pipeline 110 from the output end of the second ball valve 107.

[0048] In one embodiment of the present application, Figure 1 As shown, the well site throttling system further includes: a third ball valve 106, the input end and the output end of the third ball valve 106 are respectively connected to the two ends of the flow meter 105 through pipelines, thereby forming a bypass branch of the flow meter 105. When the flow meter 105 is replaced, the third ball valve 106 is opened, and the low-pressure natural gas from the ground throttling device 102 reaches the input end of the third ball valve 106 through the pipeline, and reaches the low-pressure external transmission pipeline 110 from the output end of the third ball valve 106 through the pipeline.

[0049] In one embodiment of the present application, the well site throttling system further includes: a fourth ball valve 103, the input end of the fourth ball valve 103 is connected to the gas production tree 108 through a pipeline, and the output end of the fourth ball valve 103 is connected to the venting pipeline 109 through a pipeline. In actual application, when the natural gas pressure is abnormal, the emergency shut-off valve 101 is closed, and the natural gas reaches the input end of the ball valve from the gas production tree through the pipeline, and reaches the venting pipeline 109 from the output end of the ball valve through the pipeline, so as to realize the venting of the natural gas.

[0050] In one embodiment of the present application, Figure 2 As shown, in addition to the throttling device body 201, the ground throttling device 102 also includes: a fifth ball valve 202, a first pressure gauge 203, a first thermometer 204, a second pressure gauge 209, a second thermometer 210, and a flow meter 211, wherein the input end of the ball valve is used to connect to a natural gas wellhead to obtain natural gas, the output end of the ball valve is connected to the input end of the first pressure gauge 203 through a pipeline, the output end of the first pressure gauge 203 is connected to the input end of the first thermometer 204, and the first thermometer 211 is connected to the input end of the first thermometer 204. The output end of the meter 204 is connected to the input end of the throttling device body 201, the output end of the throttling device body 201 is connected to the input end of the second pressure gauge 209, the output end of the second pressure gauge 209 is connected to the input end of the second thermometer 210, the output end of the second thermometer 210 is connected to the input end of the flow meter 211, the output end of the flow meter 211 is used to connect to the low-pressure external transmission pipeline 110 to output the reduced-pressure natural gas, and the flow meter 211 is used to measure the flow passing through.

[0051] The connection order of the first pressure gauge 203 and the first thermometer 204 can be swapped, and the connection order of the second pressure gauge 209 and the second thermometer 210 can be swapped.

[0052] The specific structure of the throttling device body 201 is described below. In one embodiment of the present application, Figure 2 As shown, the throttling device body 201 includes a plurality of throttling orifice plates 205 to 208, which are arranged at a predetermined distance between each other, and the predetermined distance forms a diffusion section, which is used to ensure that the temperature of the natural gas is always above the critical temperature of the natural gas hydrate. A throttling hole is provided on each of the throttling orifice plates, and the aperture of the throttling hole gradually decreases along the throttling direction of the throttling device body 201, that is, each throttling orifice plate in the throttling device body 201 can have a different aperture size, and the aperture size is obtained by calculation according to the pressure difference between the two ends of the throttling device body 201.

[0053] like Figure 3As shown, after the gas passes through the throttling hole of the throttling orifice plate, it reaches the diffusion section, is fully developed, and the temperature returns to the initial temperature before throttling. Figure 4 The average temperature distribution of the axial cross-section mass flow is shown in Fig. Figure 4 As shown in the figure, after passing through the throttling hole of the throttling orifice plate, the temperature of the natural gas in the diffusion section will return to the initial temperature before throttling, and basically does not decrease. The temperature always remains above the critical temperature of natural gas hydrate. After passing through the throttling hole, the natural gas pressure is as follows Figure 5 The step-wise descent shown finally reduces the pressure of the natural gas after passing through N levels of orifice plates.

[0054] The number of throttling orifice plates included in the throttling device body 201 is related to the initial pressure and final pressure, the medium, the initial temperature and other conditions. Figure 6 D in the figure indicates the diameter of the throttling orifice plate, p1 indicates the inlet pressure of the medium of the multi-stage throttling orifice plate (MPa), p2 indicates the outlet pressure of the medium of the multi-stage throttling orifice plate (MPa), q m It indicates the flow rate of the medium per unit time. The aperture size of each stage can be determined so that no hydrate is formed at the throttling hole of each throttling orifice plate and no blocked flow is formed.

[0055] In one embodiment of the present application, the throttling orifice plate in the throttling device body 201 may adopt the following structure, such as Figure 7 As shown, the orifice width of each throttling orifice plate close to the pipe side wall is greater than the orifice width at the throttling hole end, D is the diameter of the throttling orifice plate, d is the throttling hole size, E is the orifice width, e is the throttling throat width, θ is the throat diffusion angle, and e is smaller than E.

[0056] Each throttling orifice in the throttling device body 201 is disposed in a pipe in the ground throttling device 102 through a flange connection. The ground throttling device 102 is provided with an insulation layer, which is made of insulation rock wool to ensure that no temperature loss is generated during the pressure reduction and throttling process and is not affected by the environment.

[0057] The present application provides a well site throttling method, such as Figure 8 As shown, the following steps are included:

[0058] S1, transporting natural gas from a natural gas wellhead to a surface throttling device 102;

[0059] S2, performing multi-stage pressure reduction and throttling on the natural gas through the ground throttling device 102 to obtain natural gas that meets the wellhead pipeline pressure, and controlling the temperature of the natural gas to always be above the critical temperature of natural gas hydrate, wherein the ground throttling device 102 includes a throttling device body 201, and the throttling device body 201 includes a plurality of throttling orifice plates, the throttling orifice plates are arranged at a predetermined distance, and a throttling hole is provided on each of the throttling orifice plates;

[0060] S3, transporting the natural gas that meets the wellhead pipeline pressure to the downstream pipeline through the low-pressure external transmission pipeline 110.

[0061] Specifically, refer to Figure 1 The high-pressure natural gas from the natural gas wellhead reaches the ground throttling device 102 through a pipeline, and is subjected to multi-stage pressure reduction and throttling to form low-pressure natural gas. The low-pressure natural gas reaches the low-pressure external transmission pipeline 110 from the output end of the ground throttling device 102 through a pipeline, wherein the input end of the ground throttling device 102 is connected to the natural gas wellhead through a pipeline, and is used to obtain the high-pressure natural gas from the natural gas wellhead. The ground throttling device 102 is used to throttle and reduce the pressure of the high-pressure natural gas to obtain low-pressure natural gas that meets the transmission requirements or production requirements. The output end of the ground throttling device 102 is connected to the low-pressure external transmission pipeline 110 through a pipeline, and is used to transmit the low-pressure natural gas to the downstream pipeline.

[0062] The well site throttling method provided in the present application can achieve throttling of high-pressure natural gas at the natural gas wellhead after passing through a ground throttling device while ensuring that the temperature is not lower than the natural gas hydrate formation temperature and reaches a low-pressure external transmission pipeline without producing natural gas hydrates. The operation is simple, the cost is low, and the natural gas well site gathering and transportation process is simplified.

[0063] In one embodiment of the present application, natural gas from a natural gas wellhead is transported to a surface throttling device 102, including:

[0064] Obtain natural gas from a gas tree 108 at a natural gas wellhead;

[0065] The natural gas is transported to the ground throttling device 102 through the emergency shut-off valve 101 .

[0066] Specifically, high-pressure natural gas reaches the input end of the ground throttling device 102 from the output end of the emergency shut-off valve 101 through a pipeline. After multi-stage throttling and pressure reduction in the ground throttling device 102, the low-pressure natural gas reaches the low-pressure external transmission pipeline 110 from the output end of the ground throttling device 102 through a pipeline. The input end of the emergency shut-off valve 101 is connected to the gas production tree 108 through a pipeline to obtain high-pressure natural gas from the natural gas wellhead. The output end of the emergency shut-off valve 101 is connected to the input end of the ground throttling device 102 through a pipeline, so as to be able to cut off in time when there is an emergency accident or abnormal natural gas pressure, so as to avoid high-pressure natural gas from entering the ground throttling device 102 and causing damage to the device.

[0067] In one embodiment of the present application, the ground throttling device 102 is used to perform multi-stage pressure reduction and throttling on natural gas, including:

[0068] The natural gas is subjected to multi-stage pressure reduction and throttling through the multiple throttling orifice plates in the throttling device body 201 .

[0069] In one embodiment of the present application, the natural gas meeting the wellhead pipeline pressure is transported to the downstream pipeline through the low-pressure external transmission pipeline 110, including:

[0070] Obtaining natural gas from the ground throttling device 102;

[0071] The natural gas is transported to the downstream pipeline through the low-pressure transmission pipeline 110 after the flow rate is detected by the flow meter 105 .

[0072] Specifically, the low-pressure natural gas from the ground throttling device 102 reaches the input end of the flow meter 105 from the output end of the ground throttling device 102 through a pipeline, and then reaches the low-pressure external transmission pipeline 110 from the output end of the flow meter 105 through a pipeline after flow detection by the flow meter 105, and is transported to the downstream pipeline through the low-pressure external transmission pipeline 110, wherein the flow meter 105 is used to measure the passing flow, the input end of the flow meter 105 is connected to the output end of the ground throttling device 102 through a pipeline, and the output end of the flow meter 105 is connected to the low-pressure external transmission pipeline 110 through a pipeline.

[0073] In one embodiment of the present application, the well site throttling method further includes: a venting pipeline 109 is provided between the gas tree 108 and the emergency shut-off valve 101; the venting pipeline 109 is used to vent the natural gas by closing the emergency shut-off valve 101 when the natural gas pressure is abnormal.

[0074] Specifically, the venting pipeline 109 may have a fourth ball valve, the input end of the fourth ball valve is connected to the gas production tree 108 through a pipeline, and the output end of the ball valve is connected to the venting pipeline 109 through a pipeline, so that when the natural gas pressure is abnormal, the emergency shut-off valve 101 is closed, and the natural gas reaches the input end of the ball valve from the gas production tree through the pipeline, and reaches the venting pipeline 109 from the output end of the ball valve through the pipeline, thereby realizing the venting of natural gas.

[0075] In one embodiment of the present application, the well site throttling method further includes: forming a bypass branch of the flow meter 105 at both ends of the flow meter 105; the bypass branch is used to allow natural gas to reach the low-pressure external transmission pipeline 110 from the bypass branch when the flow meter 105 is replaced.

[0076] Specifically, the bypass branch may include a third ball valve 106, and the input end and the output end of the third ball valve 106 are respectively connected to the two ends of the flow meter 105 through pipelines, thereby forming a bypass branch of the flow meter 105. When the flow meter 105 is replaced, the third ball valve 106 is opened, and the low-pressure natural gas from the ground throttling device 102 reaches the input end of the third ball valve 106 through the pipeline, and reaches the low-pressure external transmission pipeline 110 from the output end of the third ball valve 106 through the pipeline.

[0077] The preferred specific implementation modes and embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above implementation modes and embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the concept of the present application.

Claims

1. A ground throttling device, characterized in that: The invention comprises a throttling device body (201), wherein the throttling device body (201) throttles and reduces the pressure of natural gas flowing through the throttling device body (201), and ensures that the temperature of the natural gas is always above the critical temperature of natural gas hydrates, wherein the throttling device body (201) comprises a plurality of throttling orifice plates, wherein the throttling orifice plates are arranged at a predetermined distance, and a diffusion section is formed between adjacent throttling orifice plates, and a throttling hole is provided on each throttling orifice plate; each throttling orifice plate in the throttling device body (201) has a different aperture size, and the aperture size is determined so that no hydrate is formed at the throttling hole of each throttling orifice plate and no blocking flow is formed, and the aperture of the throttling hole gradually decreases along the throttling direction of the throttling device body (201); the natural gas flowing through the throttling device body (201) is constructed to reach the diffusion section after passing through the throttling hole of the throttling orifice plate, and the temperature rises during the process of full expansion of the diffusion section, so as to ensure that the temperature of the natural gas is always above the critical temperature of natural gas hydrates; The orifice width of each throttling orifice plate in the throttling device body (201) close to the pipeline side wall is greater than the orifice width at the throttling hole end.

2. The ground throttling device according to claim 1, characterized in that: Also includes: A ball valve (202), a first pressure gauge (203), a first thermometer (204), a second pressure gauge (209), a second thermometer (210), and a flow meter (211), wherein: The input end of the ball valve (202) is used to connect with wellhead natural gas to obtain natural gas, the output end of the ball valve (202) is connected to the input end of the first pressure gauge (203) through a pipeline, the output end of the first pressure gauge (203) is connected to the input end of the first thermometer (204), the output end of the first thermometer (204) is connected to the input end of the throttling device body (201), the output end of the throttling device body (201) is connected to the input end of the second pressure gauge (209), the output end of the second pressure gauge (209) is connected to the input end of the second thermometer (210), the output end of the second thermometer (210) is connected to the input end of the flow meter (211), and the output end of the flow meter (211) is used to connect to a low-pressure external transmission pipeline to output the reduced-pressure natural gas.

3. The ground throttling device according to claim 1, characterized in that: Also includes: A ball valve (202), a first pressure gauge (203), a first thermometer (204), a second pressure gauge (209), a second thermometer (210), and a flow meter (211), wherein: The input end of the ball valve (202) is used to connect with wellhead natural gas to obtain natural gas, the output end of the ball valve (202) is connected to the input end of the first thermometer (204) through a pipeline, the output end of the first thermometer (204) is connected to the input end of the first pressure gauge (203), the output end of the first pressure gauge (203) is connected to the input end of the throttling device body (201), the output end of the throttling device body (201) is connected to the input end of the second thermometer (210), the output end of the second thermometer (210) is connected to the input end of the second pressure gauge (209), the output end of the second pressure gauge (209) is connected to the input end of the flow meter (211), and the output end of the flow meter is used to connect to a low-pressure external transmission pipeline to output the reduced-pressure natural gas.

4. The ground throttling device according to claim 2 or 3, characterized in that: Each throttling orifice plate in the throttling device body (201) is arranged in a pipeline in the ground throttling device (102) through a flange connection.

5. The ground throttling device according to claim 2 or 3, characterized in that: The ground throttling device (102) is provided with a thermal insulation layer.

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