Sulfur-containing natural gas flow measurement system and flow measurement method

Abstract

The invention discloses a sulfur-containing natural gas flow measuring system and method.The sulfur-containing natural gas flow measuring system comprises a testing pipeline, a tracer agent and / or desulfurizer filling unit and a laser Doppler speed measuring unit, and the emitting end of the filling unit is arranged in the testing pipeline; the laser emitting end of the laser Doppler velocity measurement unit is perpendicular to the test pipeline, and the test pipeline is made of a transparent material or is provided with a visual window. The application requirement of the laser Doppler velocity measurement technology in the field of sulfur-containing natural gas test pipeline flow velocity measurement is met, visualization can be achieved, and the test result is accurate. According to the device, whether sulfur is attached to the interior of the test pipeline or deposited or not can be visually found through the test pipeline, when attachments or other impurities are found, the test pipeline can be cleaned by adding a sulfur solvent, and gas does not need to be stopped for cleaning the test pipeline in the cleaning process; the production is not influenced, and the cleaning burden and the safety risk are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas measurement, and in particular to a sulfur-containing natural gas flow measurement system and a flow measurement method. Background Art

[0002] The exploitation of sour natural gas reservoirs accounts for about 50% of the natural gas development volume. The exploitation and production of high-sulfur natural gas is more technically difficult than conventional natural gas, and its metering technology also has greater technical difficulties and challenges.

[0003] At present, there is still a lack of effective methods and technical means for the measurement of high-sulfur natural gas. In the actual production process, the measurement of high-sulfur natural gas directly applies the measurement methods and standards of conventional natural gas. The most widely used on-site are standard orifice flowmeters and other types of flowmeters. For the use of orifice flowmeters, due to the changes in pressure, temperature and other conditions during the gathering and transportation of sour natural gas, the elemental sulfur dissolved in the gas may precipitate and deposit in the gathering and transportation test pipeline in the form of solid particles. Sulfur deposition will cause "sulfur blockage" in the ground gathering and transportation test pipeline. If sulfur is deposited on the inner wall of the test pipeline upstream of the flowmeter, it will affect the flow field, forming an unstable flow field, and ultimately affecting the normal measurement of gas flow. In order to reduce the impact of sulfur deposition on measurement, it is necessary to clean it regularly to ensure its accurate measurement. For the production of high-sulfur natural gas, frequent cleaning and disassembly of the flowmeter brings more safety risks and work burdens to the production site.

[0004] Therefore, it is necessary to establish a flow meter or a metering method and system for measuring the flow of sour natural gas that does not require disassembly, is easy to clean, and has relatively little effect of sulfur deposition on its metering accuracy. Summary of the invention

[0005] The technical problem to be solved by the present invention is that in the existing production of high-sulfur natural gas, frequent cleaning and disassembly of flow meters brings more safety risks and work burdens to the production site.

[0006] The first object of the present invention is to provide a sour natural gas flow measurement system, comprising a test pipeline, a tracer and / or desulfurizer filling unit and a laser Doppler velocimeter unit, wherein the exit end of the tracer and / or desulfurizer filling unit is arranged in the test pipeline, the laser exit end of the laser Doppler velocimeter unit and the test pipeline are arranged vertically, and the test pipeline is made of a transparent material or has a visualization window opened thereon.

[0007] As a possible design, a temperature measuring unit and a pressure measuring unit are further provided on the test pipe, and the laser Doppler velocity measuring unit is communicatively connected to a data processing unit, and the data processing unit is communicatively connected to the temperature measuring unit and the pressure measuring unit.

[0008] As a possible design, two parallel flanges are provided on the test pipe, and the laser emitting end of the laser Doppler velocity measurement unit and the test pipe disposed between the two flanges are vertically arranged.

[0009] As a possible design, the tracer and / or desulfurizer filling unit includes a tracer storage structure, a desulfurizer storage structure, an atomizing nozzle and an air source storage structure. The air source storage structure is connected to the tracer storage structure and the desulfurizer storage structure respectively, and the atomizing nozzle is connected to the tracer storage structure and the desulfurizer storage structure respectively. The atomizing nozzle is arranged in the test pipeline.

[0010] As a possible design, the tracer storage structure includes a tracer storage tank, the tracer storage tank is provided with a first adding port, and the first adding port is provided with a first sealing cover.

[0011] As a possible design, the desulfurizer storage structure includes a desulfurizer storage tank, the desulfurizer storage tank is provided with a second addition port, and the second addition port is provided with a second cover.

[0012] As a possible design, a first valve is provided on the pipeline connecting the gas source storage structure and the desulfurizer storage structure; a second valve is provided on the pipeline connecting the tracer storage structure and the gas source storage structure.

[0013] As a possible design, a first one-way valve is provided on the pipeline connecting the atomizing nozzle and the tracer storage structure, and a second one-way valve is provided on the pipeline connecting the atomizing nozzle and the desulfurizing agent storage structure.

[0014] The beneficial effects of the present invention are:

[0015] (1) The present invention can meet the application requirements of laser Doppler velocimetry (LDV) technology in the field of flow velocity measurement of sulfur-containing natural gas test pipelines, can achieve visualization, and the test results are accurate.

[0016] (2) During the flow metering process, the present invention can visually detect whether there is sulfur attached to the test pipeline or sulfur deposition in the test pipeline. When attachments or other impurities are found, the test pipeline can be cleaned by adding sulfur solvent. During the cleaning process, there is no need to stop the gas for cleaning the test pipeline. Therefore, it not only does not affect production, but also reduces the cleaning burden and safety risks.

[0017] The second object of the present invention is to provide a flow measurement method based on the aforementioned sour natural gas flow measurement system, comprising:

[0018] The laser Doppler velocity measurement unit is started and two coherent light waves are emitted into the test pipe to form a measurement body, and the Doppler frequency shift is obtained and transmitted to the data processing module; the data processing module calculates the volume flow rate of the fluid;

[0019] When sediment appears in the test pipeline, the tracer and / or desulfurization agent filling unit is started; when the sediment disappears, the tracer and / or desulfurization agent filling unit is stopped.

[0020] As a possible design, the data processing module is calculated based on the following principles:

[0021]

[0022] Among them, Q VS To test the volume flow rate inside the pipe, V N+1 R N+1 is the outer diameter of the ring and R N The equivalent velocity of the annulus inside the ring is the inner diameter of the ring.

[0023] Beneficial effects of the present invention:

[0024] The data processing module disclosed in the present invention is based on a simple principle, has accurate calculation results, and has little effect of sulfur precipitation on flow calculation results, so it is worthy of popularization and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0026] Figure 1 Schematic diagram of a sour natural gas flow measurement system according to an embodiment of the present invention;

[0027] Figure 2 is a schematic diagram of a filling unit in an embodiment of the present invention;

[0028] Figure 3 It is a schematic diagram of Doppler circulation integral calculation in an embodiment of the present invention.

[0029] Marks and corresponding parts names in the attached drawings:

[0030] 1-test pipeline; 2-temperature measuring unit; 3-flange; 4-pressure measuring unit; 5-laser Doppler velocimetry unit; 6-data processing unit; 7-tracer and / or desulfurizer filling unit; 8-second sealing cover; 9-first adding port; 10-nozzle; 11-first valve; 12-atomizing nozzle; 13-second one-way valve; 14-first one-way valve; 15-first valve; 16-tracer storage tank; 17-sulfur solvent storage tank; 18-gas source storage tank. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0032] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0034] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "front", "back", "left", "right", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] For the transportation of high-sulfur natural gas, a flow meter is installed on the transportation test pipeline. However, due to the high sulfur content, it is easy to precipitate on the inlet test pipeline of the flow meter, so the flow meter needs to be removed for cleaning. For high-sulfur natural gas, the flow meter needs to be frequently disassembled, which brings more safety risks and work burdens to the production site.

[0037] In response to the above problems, Figure 1 As shown, an embodiment of the present invention provides a sulfur-containing natural gas flow measurement system. Figure 1 As shown, the sour natural gas flow measurement system includes a test pipeline 1, a tracer and / or desulfurizer filling unit 7 and a laser Doppler velocimeter unit 5, the exit end of the tracer and / or desulfurizer filling unit 7 is arranged in the test pipeline 1, the laser exit end of the laser Doppler velocimeter unit 5 and the test pipeline 1 are vertically arranged, and the test pipeline 1 is made of a transparent material or has a visualization window opened thereon.

[0038] Figure 1 In the figure, the direction indicated by the arrow is the direction of sour natural gas flow. First, the laser Doppler velocity measurement unit is started, which emits two coherent light waves to the test pipeline to form a measuring body. Then the sour natural gas is started to flow, and the sour natural gas forms a scatterer. When the scatterer passes through the measuring body, the frequency of the scattered light wave will deviate from the frequency of the emitted light wave. The magnitude of the offset is the Doppler frequency shift, which is related to the movement speed of the scatterer. The information such as the movement speed of the scatterer can be obtained by processing the signal receiver and the laser Doppler processing unit.

[0039] When the tracer particles following the fluid pass through the measurement test pipeline, the relationship between the Doppler frequency of the light intensity signal scattered by the particles and the particle movement speed is as follows.

[0040]

[0041] Where λ is the wavelength of the emitted light, θ is the angle between the two coherent beams, f is the Doppler frequency, V LDV is the gas flow rate.

[0042] The calculation formula for the flow rate of the test pipeline section can be expressed as:

[0043]

[0044] Where Q is the flow rate of the test pipe cross section, n represents the number of query areas, V n is the velocity of each query area, and S is the cross-sectional area of ​​the test pipe.

[0045] like Figure 3 As shown in the figure, the speed of each query area can be measured by the laser Doppler speed measurement unit, which is Vn-1 、V n 、V n+1 、V n+2 The distance between adjacent query areas is the parameter R set by the laser Doppler velocity measurement unit. D Assume that the distance between the query area N1 near the center of the test pipe and the center of the test pipe is R1 (R1 <R D ), since the distance R1 is very small and the fluid velocity is symmetrical along the center line, it can be considered that the velocity in the ring with R1 as the radius and the center of the test pipe as the center is V1, and it is called the equivalent velocity on the ring surface, referred to as the ring surface equivalent velocity. N is the inner diameter, R N+1 The equivalent velocity of the ring surface in the ring with an outer diameter is V N+1 .

[0046] From formula (2), we can get the area of ​​each ring surface:

[0047]

[0048] In the formula, S N is the annulus area, R N is the inner diameter of the ring, R N+1 is the outer diameter of the ring.

[0049] The volume flow rate through each annulus can be calculated according to Formula 3:

[0050] Q VN =V N ·S N (3)

[0051] In the formula, Q VN is the annular flow rate, V N is the torus equivalent velocity

[0052] By integrating all the annular flows inside the test pipe, the volume flow rate inside the entire pipe can be obtained:

[0053]

[0054] In the formula, Q VS It is the volume flow rate inside the test pipe.

[0055] Since the test pipeline is made of transparent material or has a visual window, the operator can start the filling unit when observing sediment or other impurities in the test pipeline. The filling unit fills the desulfurizer into the test pipeline. The desulfurizer comes into contact with the sediment to dissolve the sediment. The whole process does not require stopping the delivery of natural gas and does not affect production.

[0056] In order to obtain the volume flow rate of natural gas under standard conditions, such as Figure 1 As shown, the test pipe 1 is also provided with a temperature measuring unit 2 and a pressure measuring unit 4 , the laser Doppler velocity measuring unit 5 is communicatively connected to a data processing unit 6 , and the data processing unit 6 is communicatively connected to the temperature measuring unit 2 and the pressure measuring unit 4 .

[0057] The data processing unit 6 calculates the volume according to the following formula:

[0058]

[0059] Among them, V0 is the volume under standard conditions, P0 is a standard atmospheric pressure, T0 is the standard temperature (such as 20°C), P I and T I are the pressure and temperature measured by the temperature and pressure measuring device, V I It is the actual volume of the natural gas measured, which is calculated from the flow rate and time measured by the laser Doppler velocity measurement unit.

[0060] like Figure 1 As shown, two parallel flanges 3 are arranged on the test pipe 1, and the laser emitting end of the laser Doppler velocity measurement unit 5 and the test pipe 1 arranged between the two flanges 3 are arranged vertically, so as to facilitate the replacement of the test pipe 1.

[0061] like Figure 1 As shown, the tracer and / or desulfurizer filling unit 7 includes a tracer storage structure, a desulfurizer storage structure, an atomizing nozzle 12 and an air source storage structure. The air source storage structure is connected to the tracer storage structure and the desulfurizer storage structure respectively. The atomizing nozzle 12 is connected to the tracer storage structure and the desulfurizer storage structure respectively. The atomizing nozzle 12 is arranged in the test pipeline 1.

[0062] The tracer storage structure is used to add tracers into the test pipe 1, and the desulfurizer storage structure is used to add desulfurizer into the test pipe 1 to eliminate deposited precipitation. The gas source storage structure contains high-pressure gas, which enters the tracer storage structure and the desulfurizer storage structure, and brings the liquid tracer and desulfurizer to the atomizing nozzle 12 and atomizes them.

[0063] like Figure 1 As shown, the tracer storage structure includes a tracer storage tank 16 , and the tracer storage tank 16 is provided with a first adding port 9 , and the first adding port 9 is provided with a first sealing cover.

[0064] The desulfurizing agent storage structure comprises a desulfurizing agent storage tank, the desulfurizing agent storage tank is provided with a second adding port, and the second adding port is provided with a second sealing cover 8 .

[0065] A first valve 11 is provided on the pipeline connecting the gas source storage structure and the desulfurizer storage structure; a second valve is provided on the pipeline connecting the tracer storage structure and the gas source storage structure.

[0066] A first one-way valve 14 is provided on the pipeline connecting the atomizing nozzle 12 and the tracer storage structure, and a second one-way valve 13 is provided on the pipeline connecting the atomizing nozzle 12 and the desulfurizing agent storage structure.

[0067] The corresponding liquid substances are stored in the tracer storage tank 16 and the desulfurizer storage tank. When the corresponding liquid substances need to be added, it is only necessary to open the corresponding valve to connect the test pipeline 1 and start the gas source storage structure. The gas source provides high-pressure gas. In the case of pressure difference, the gas brings the liquid into the atomizing nozzle 12 and sprays it into the test pipeline 1 after atomization, thereby realizing the addition of reagents. The atomizing nozzle 12 can be a common atomizing device, such as a shower head.

[0068] For example, when it is necessary to add tracer, the first valve 11 and the second one-way valve 13 are closed, and then the first one-way valve 14 and the second valve are opened, and the high-pressure gas source enters the tracer storage tank 16 to bring the tracer into the atomizing nozzle 12 .

[0069] For another example, when desulfurizer needs to be added, the second valve and the first one-way valve 14 are closed, and then the second one-way valve 13 and the first valve 11 are opened, and the high-pressure gas source enters the desulfurizer storage tank to bring the desulfurizer into the atomizing nozzle 12 .

[0070] In actual application, the atomizing nozzle 12 is arranged in the test pipeline 1, and the liquid inlet end of the atomizing nozzle 12 is connected to a nozzle 10, and the nozzle 10 is connected to the tracer storage tank 16 and the desulfurizer storage tank respectively; in order to improve the accuracy of flow measurement, the pipeline can be telescopic, so as to realize the spraying of tracer particles at the upper, middle and lower positions of the fluid.

[0071] The test pipe 1 is a transparent circular pipe, such as a plexiglass pipe. In order to avoid corrosion by sulfur-containing substances, the inner wall of the transparent pipe can be covered with an anti-sulfur coating.

[0072] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A sulfur-containing natural gas flow measurement system, characterized in that: It comprises a test pipeline, a tracer and / or desulfurization agent filling unit and a laser Doppler velocimeter unit. The exit end of the tracer and / or desulfurization agent filling unit is arranged in the test pipeline. The laser exit end of the laser Doppler velocimeter unit is arranged vertically to the test pipeline. The test pipeline is made of a transparent material or has a visualization window.

2. The sour natural gas flow measurement system according to claim 1, characterized in that: The test pipeline is also provided with a temperature measuring unit and a pressure measuring unit. The laser Doppler velocity measuring unit is communicatively connected to a data processing unit. The data processing unit is communicatively connected to the temperature measuring unit and the pressure measuring unit.

3. The sour natural gas flow measurement system according to claim 1, characterized in that: The test pipeline is provided with two parallel flanges, and the laser emitting end of the laser Doppler velocity measuring unit and the test pipeline arranged between the two flanges are arranged vertically.

4. The sour natural gas flow measurement system according to claim 1, characterized in that: The tracer and / or desulfurizer filling unit includes a tracer storage structure, a desulfurizer storage structure, an atomizing nozzle and an air source storage structure. The air source storage structure is connected to the tracer storage structure and the desulfurizer storage structure respectively. The atomizing nozzle is connected to the tracer storage structure and the desulfurizer storage structure respectively. The atomizing nozzle is arranged in the test pipeline.

5. The sour natural gas flow measurement system according to claim 4, characterized in that: The tracer storage structure comprises a tracer storage tank, the tracer storage tank is provided with a first adding port, and the first adding port is provided with a first sealing cover.

6. The sour natural gas flow measurement system according to claim 4, characterized in that: The desulfurizing agent storage structure comprises a desulfurizing agent storage tank, the desulfurizing agent storage tank is provided with a second adding port, and the second adding port is provided with a second sealing cover.

7. The sour natural gas flow measurement system according to claim 4, characterized in that: A first valve is provided on the pipeline connecting the gas source storage structure and the desulfurizer storage structure; a second valve is provided on the pipeline connecting the tracer storage structure and the gas source storage structure.

8. The sour natural gas flow measurement system according to claim 4, characterized in that: A first one-way valve is arranged on the pipeline connecting the atomizing nozzle and the tracer storage structure, and a second one-way valve is arranged on the pipeline connecting the atomizing nozzle and the desulfurizing agent storage structure.

9. The flow measurement method based on the sour natural gas flow measurement system according to any one of claims 1 to 8, characterized in that: The flow measurement method comprises: The laser Doppler velocity measurement unit is started and two coherent light waves are emitted into the test pipe to form a measurement body, and the Doppler frequency shift is obtained and transmitted to the data processing module; the data processing module calculates the volume flow rate of the fluid; When sediment appears in the test pipeline, the tracer and / or desulfurization agent filling unit is started; when the sediment disappears, the tracer and / or desulfurization agent filling unit is stopped.

10. The flow measurement method according to claim 9, characterized in that: The data processing module is calculated based on the following principles: Among them, Q VS To test the volume flow rate inside the pipe, V N+1 R N+1 is the outer diameter of the ring and R N The equivalent velocity of the annulus inside the ring is the inner diameter of the ring.

Images