Water content measuring system and method based on flexible conformal antenna sensor

Abstract

The invention discloses a moisture content measuring system and method based on a flexible conformal antenna sensor. Amplitude attenuation and phase deviation can occur when a microwave signal is propagated in a fluid to be measured, amplitude attenuation and phase deviation values are related to the dielectric constant of the fluid to be measured, and the dielectric constant of water at normal temperature is about 78 and is greatly different from the dielectric constant of oil or air. According to the invention, the moisture content information can be obtained by detecting the amplitude attenuation and the phase deviation value under the fixed frequency point. According to the invention, 0-100% full-scale moisture content measurement can be realized. The flexible conformal antenna sensor breaks through the fixed mode that the convex surface of a traditional conformal antenna radiates outwards, the design that the circular patch is embedded in the concave surface is adopted, the direction of a main wave beam is centripetally focused in the radial direction of a pipeline, directional radiation of electromagnetic waves to a to-be-detected fluid pipeline area is achieved, and the energy coupling efficiency between the electromagnetic waves and fluid is improved; and the dielectric property change of the whole watershed of the fluid is detected.

Description

Technical Field

[0001] The present invention belongs to the technical field of two-phase flow water cut measurement. Specifically, it particularly relates to a water cut measurement system and method based on a flexible conformal antenna sensor. Background Art

[0002] During the process of oil or natural gas extraction, the wellhead produced fluid is mostly oil-water or gas-water two-phase flow. Its water cut is not only a benchmark parameter for evaluating the productivity of a single well, but also a core index for optimizing oil and gas reservoir management and predicting equipment life.

[0003] Existing water cut measurement methods are divided into two categories: separation type and non-separation type. Although the separation type method has high accuracy, it has problems such as high equipment price and low measurement efficiency. The non-separation type method, although low in cost and strong in real-time performance, is difficult to cover the full range and has insufficient accuracy due to the interference of complex flow patterns.

[0004] Currently, the non-separation methods mainly include conductivity method, capacitance method, ray method, microwave method, etc. Among them, the conductivity method and capacitance method, although low in cost, are easily affected by flow patterns. For example, in flow patterns such as stratified flow and bubbly flow, the test accuracy in the high water cut section is low and the full range cannot be covered. Although the ray method can cover the full range, the risk of radioactive pollution restricts its popularization and application. In contrast, the microwave method realizes non-contact measurement based on the difference in the dielectric properties of the fluid to be measured, and has advantages such as no pollution and high accuracy. Therefore, the microwave method has gradually become a research hotspot in the field of two-phase flow detection. Although existing commercial microwave water cut meters have covered full range measurement, invasive measurement has problems such as the sensor being easily corroded by the fluid, the flow pattern being interfered by the probe, low accuracy, and poor stability. Summary of the Invention

[0005] The purpose of the present invention is to solve the problems urgently to be solved in the above background art, and provide a water cut measurement system and method based on a flexible conformal antenna sensor. The present invention mainly utilizes that when a microwave signal propagates in the fluid to be measured, its amplitude attenuation and phase shift will occur. The magnitudes of the amplitude attenuation and phase shift values are related to the dielectric constant of the fluid to be measured. At room temperature, the dielectric constant of water is about 78, which is quite different from the dielectric constant values of oil or air. By detecting the magnitudes of the amplitude attenuation and phase shift values at a fixed frequency point, the water cut information can be obtained.

[0006] To achieve the above purpose, the present invention provides a water cut measurement system and method based on a flexible conformal antenna sensor, including:

[0007] A water cut measurement system based on a flexible conformal antenna sensor in the present invention includes:

[0008] A test pipeline body for flowing through two-phase flow;

[0009] A flexible conformal antenna sensor, comprising a transmitting end and a receiving end, wherein the transmitting end and the receiving end are axially symmetrically attached and installed to the outer wall surface of a test pipeline;

[0010] A vector network analyzer, whose first port is connected to the transmitting end of the flexible conformal antenna sensor, and whose second port is connected to the receiving end of the flexible conformal antenna sensor;

[0011] A data processing unit, connected to the vector network analyzer, for processing measurement data; including:

[0012] A data receiving module, for receiving the amplitude attenuation and phase shift information of the microwave signal transmitted by the vector network analyzer;

[0013] A data processing module, for calculating the moisture content according to the amplitude attenuation and phase shift information;

[0014] Wherein, the flexible conformal antenna sensor includes a flexible material dielectric substrate, a patch radiation unit, and a feeding structure, the patch radiation unit is arranged on the flexible material dielectric substrate, and the feeding structure is used for transmitting microwave signals to the patch radiation unit or transmitting microwave signals from the patch radiation unit.

[0015] A moisture content measurement method based on a flexible conformal antenna sensor, using the above system, comprising the following steps:

[0016] Axially symmetrically attach and install the transmitting end and the receiving end of the flexible conformal antenna sensor to the outer wall surface of the test pipeline;

[0017] Generate microwave signals at multiple frequency points through the vector network analyzer, and transmit the microwave signals to the transmitting end of the flexible conformal antenna sensor;

[0018] The transmitting end of the flexible conformal antenna sensor emits the microwave signals into the two-phase flow in the test pipeline;

[0019] The receiving end of the flexible conformal antenna sensor receives the microwave signals propagated through the two-phase flow, and transmits the microwave signals to the vector network analyzer;

[0020] The vector network analyzer receives the microwave signals, and generates the amplitude attenuation and phase shift information of the microwave signals;

[0021] The data processing unit calculates the moisture content according to the amplitude attenuation and phase shift information.

[0022] Due to the adoption of the above technical solutions, the present invention has the following advantages:

[0023] 1. The water content measurement system and method based on the flexible conformal antenna sensor designed by the present invention can achieve full-range water content measurement from 0 to 100%.

[0024] 2. The flexible conformal antenna sensor designed by the present invention breaks through the fixed mode of the traditional conformal antenna with the convex surface radiating outward, adopts a concave surface embedded circular patch design, makes the main beam direction focus centripetally along the radial direction of the pipeline, realizes the directional radiation of electromagnetic waves to the area of the fluid pipeline to be measured, improves the energy coupling efficiency between the electromagnetic waves and the fluid, ensures that the dielectric property changes in the whole basin of the fluid are detected, and improves the measurement accuracy and range.

[0025] 3. The flexible conformal antenna sensor designed by the present invention avoids the direct contact between the fluid and the sensor surface, significantly reduces the performance degradation caused by electrode corrosion and scaling, and effectively extends the service life.

[0026] 4. The flexible conformal antenna sensor designed by the present invention can be installed by fitting to the outer wall curved surface of the pipeline without invading the interior of the fluid, avoids the interference of the traditional probe to the fluid, can maintain the original flow state, and ensures that the water content detection value is consistent with the actual working condition.

[0027] 5. The flexible conformal antenna sensor designed by the present invention can be flexibly adapted to various types of pipelines, and has high engineering integration convenience. The curved surface fitting characteristic of the conformal antenna can be adapted to different pipe diameters and special-shaped pipelines without customized transformation, and has strong universality. Description of the Drawings

[0028] Figure 1 Schematic diagram of the water content measurement system based on the flexible conformal antenna sensor;

[0029] Figure 2 Schematic diagram of the flexible conformal antenna structure;

[0030] Figure 3 S11 parameter diagram of the antenna with the example structure;

[0031] Figure 4 Schematic diagram of the water content sensor based on one flexible conformal antenna;

[0032] Figure 5 Schematic diagram of the water content sensor based on two flexible conformal antennas;

[0033] Figure 6 Water content prediction result based on the S11 amplitude;

[0034] Figure 7 Water content prediction result based on the S21 phase;

[0035] Figure 8 Water content prediction result based on the S21 amplitude. Detailed Embodiment

[0036] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] As Figure 1 shown, the embodiment of the present application provides a water content measurement system based on a flexible conformal antenna sensor, including: a test pipeline 1 through which a two-phase flow passes; a flexible conformal antenna sensor transmitting end 2 and a receiving end 3 axially symmetrically attached to the outer wall surface of the pipeline; a vector network analyzer 4, a first port of the vector network analyzer is connected to the transmitting end of the flexible conformal antenna sensor through an SMA connector, a second port of the vector network analyzer is connected to the receiving end of the flexible conformal antenna sensor through an SMA connector, and a computer 5 connected to the vector network analyzer for processing data.

[0038] Furthermore, the flexible conformal antennas are classified by patch shape into circular patch antennas, rectangular patch antennas, elliptical patch antennas, and annular patch antennas; classified by feeding method into microstrip line feeding, coaxial probe feeding, and coupled feeding; classified by polarization method into linear polarization, circular polarization, and elliptical polarization;

[0039] Preferably, the structures of the transmitting end of the flexible conformal antenna sensor and the receiving end of the flexible conformal antenna sensor are the same. The embodiment of the present application adopts a conformal circular patch and feeds it in a coaxial probe manner;

[0040] In an embodiment, as Figure 2 shown, the conformal circular patch antenna includes:

[0041] A flexible material dielectric substrate 6, the substrate material is Taconic TLX-8, and the material has good flexibility and can conformally adhere to the outer surface of the pipeline.

[0042] A circular patch radiation unit 7, which has higher radiation efficiency, wider bandwidth, and more compact structure than a rectangular patch under the working frequency band of the sensor in the embodiment of the present application.

[0043] A coaxial probe, including an inner conductor 8, an outer conductor 9, and a filling medium 10.

[0044] Different from traditional conformal antennas, the designed conformal flexible antenna realizes the directional energy radiation of electromagnetic waves to the space of the fluid pipeline to be measured below through the radiation unit arranged at the bottom of the dielectric substrate.

[0045] Considering the actual working conditions of two-phase flow moisture content measurement, the length, width, and thickness of the flexible antenna dielectric plate, the radius of the circular patch, the position of the inner conductor feeding point, the radius of the inner conductor, the radius of the filling medium, and the length of the inner conductor are simulated and optimized in the three-dimensional structure electromagnetic field simulation software Ansoft HFSS. Here is an example for reference, such as Figure 2 , the dielectric plate size is 65×65 mm, the thickness is 0.508 mm, the radius of the circular conformal patch is 20 mm, the feeding point is 6 mm away from the center, the radius of the inner conductor is 0.45 mm, the radius of the outer conductor is 2.05 mm, and the length of the inner conductor is 11.8 mm. The inner diameter of the test pipe is 50 mm, and the outer diameter is 60 mm.

[0046] As Figure 3 stated, according to the above parameters, the resonant frequency of the flexible conformal antenna is 1.637 GHz. At this frequency, S11 < -38 dB, far exceeding the general engineering requirement of < -20 dB. The antenna can efficiently radiate signals and achieve good matching effects under the actual two-phase flow measurement conditions.

[0047] The moisture content measurement method using the flexible conformal antenna sensor described above includes:

[0048] The vector network analyzer generates microwave signals at multiple frequency points. The microwave signals are transmitted through cables and SMA interfaces to the transmitting end of the flexible conformal antenna sensor for excitation;

[0049] The transmitting end of the flexible conformal antenna sensor receives the microwave signals and transmits them; the microwave signals propagate through the fluid to be measured;

[0050] The receiving end of the flexible conformal antenna sensor receives the microwave signals and transmits them to the vector network analyzer through the SMA interface and cables;

[0051] The vector network analyzer receives the microwave signals, generates amplitude attenuation and phase shift information at multiple frequency points and displays them, and transmits them to the computer;

[0052] The computer calculates the moisture content according to the amplitude attenuation and phase shift information;

[0053] Furthermore, the computer includes:

[0054] A model fitting unit for fitting the measurement data according to a preset mathematical model of moisture content and amplitude attenuation or phase shift;

[0055] A calculation unit for calculating the moisture content according to the fitting result.

[0056] In this application, the S-parameters are a set of parameters used to describe the reflection and transmission characteristics of electromagnetic waves. S11 represents the reflection coefficient of port 1 and is used to evaluate the input matching degree. The transmission coefficient S21 represents the transmission efficiency from input port 1 to output port 2 and is used to evaluate the signal transmission loss or gain.

[0057] Assume that the incident wave at port 1 is , the reflected wave at port 1 is b1, the incident wave at port 1 is , the reflected wave at port 2 is b2, then S11 and S21 are respectively defined as:

[0058]

[0059]

[0060] For the flexible conformal antenna sensor, there is a monotonic characteristic between the amplitude and phase information collected at a certain frequency point and the moisture content. Based on this principle, the moisture content can be calculated according to the following formula:

[0061]

[0062]

[0063]

[0064] In the formula, A S11 is the amplitude in decibel form of the S11 reflection coefficient, A S21 is the amplitude in decibel form of the S21 transmission coefficient, is the phase value of the S21 transmission coefficient.

[0065] Based on the theory of electromagnetic wave propagation, when a microwave signal flows through the fluid to be measured, amplitude attenuation and phase shift phenomena will occur. The degree of amplitude attenuation and phase shift is related to the dielectric constant of the medium. At room temperature, the dielectric constant of water is about 78, which is quite different from the dielectric constant values of oil or air. The dielectric constant of the fluid to be measured is directly affected by the moisture content. To improve the measurement accuracy and robustness, the present invention proposes two implementation cases.

[0066] Example 1: A method for measuring moisture content based on a single flexible conformal antenna sensor, as Figure 4 .

[0067] Includes:

[0068] Step 1, configure a matching flexible conformal antenna sensor and measurement system according to the pipeline diameter D, wall thickness d, and the range of fluid dielectric constant ε;

[0069] Step 2, axially attach the flexible conformal antenna sensor to the outer wall surface of the pipeline;

[0070] Step 3: The vector network analyzer generates a swept microwave signal in a preset frequency band (0.1 GHz to 4 GHz). The microwave signal is transmitted to the flexible conformal antenna sensor through a coaxial cable (characteristic impedance 50 Ω) and an SMA interface. The microwave signal is reflected back to the SMA interface and the cable after passing through the fluid under test, and then transmitted to the vector network analyzer.

[0071] Step 4: The vector network analyzer receives the microwave signal, records and displays the magnitude of the S11 reflection coefficient at each frequency point, and transmits it to the computer.

[0072] Table 1

[0073]

[0074] Step 5: Based on the obtained S11 magnitude data at different water contents and the oil-water linear dielectric constant model, the mathematical model of the water content and the S11 magnitude at 3.2825 GHz is obtained by fitting the data in Table 1:

[0075]

[0076] where represents the water content in the oil-water mixture, and A S11 represents the magnitude of the S11 reflection coefficient in decibel form.

[0077] Model verification shows that when the water content is 0 - 10%, the relative error is ±1.71%, and the average relative error is 1%, as Figure 6 shown.

[0078] Furthermore, considering the requirements in terms of measurement range, accuracy, and anti-interference ability, Embodiment 2 is proposed: A water content measurement method based on two flexible conformal antenna sensors, as Figure 5 .

[0079] including:

[0080] Step 1: Select a pair of isomorphic flexible conformal antenna sensors as the transmitter (Tx) and the receiver (Rx).

[0081] Step 2: Axially and symmetrically attach the transmitter and receiver of the flexible conformal antenna sensors to the outer wall surface of the pipeline, ensuring that the near-field coupling area covers the fluid cross-section.

[0082] Step 3: The transmitting port (Port1) of the vector network analyzer emits a swept microwave signal. The microwave signal is transmitted to the transmitting end (Tx) of the flexible conformal antenna sensor through a coaxial cable (characteristic impedance 50 Ω) and an SMA interface. The microwave signal propagates through the fluid under test, and the receiving end (Rx) of the flexible conformal antenna sensor receives the microwave signal and transmits it to the receiving port (Port2) of the vector network analyzer through an SMA interface and a cable.

[0083] Step 4: The vector network analyzer receives the microwave signal, generates S21 amplitude attenuation and phase shift information at multiple frequencies and displays it. The collected amplitude and phase data are transmitted to a computer.

[0084] Table 2

[0085]

[0086] Step 5: According to the data relationship between the water content and S21 amplitude and S21 phase at the fixed frequency obtained, the data in Table 2 are fitted to obtain the following water content prediction model. The measurement results of the water content in the 0~100% full range of the oil-water two-phase flow at 0.55 GHz are as Figure 7 shown. The results show that when the water content in the full range is 0~100%, the relative error is ±3.6% and the average relative error is 2%.

[0087]

[0088] where represents the water content in the oil-water mixture, represents the phase value of the S21 transmission coefficient.

[0089] Furthermore, considering that the oil-water two-phase flow (in the low water content range) exists in the form of bubble flow under actual working conditions, which has a certain impact on the measurement accuracy. A more suitable Bruggeman mixing dielectric constant model (formula ) is selected.

[0090]

[0091] where represents the water content in the oil-water mixture; represents the relative dielectric constant of water; represents the relative dielectric constant of the mixture; represents the relative dielectric constant of oil.

[0092] Table 3

[0093]

[0094] At 3.09 GHz, the data in Table 3 was fitted to establish a moisture content measurement model based on the magnitude of S21 in the range of 0 - 10%.

[0095]

[0096] Among them, represents the moisture content in the oil - water mixture, and A S21 represents the magnitude of the S21 reflection coefficient in decibels.

[0097] The results show that when the moisture content is in the range of 0 - 10%, the relative error is ±0.9% and the average relative error is 0.4%, as Figure 8 shown.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific implementation manners of the present invention. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A moisture content measurement system based on a flexible conformal antenna sensor, characterized in that, Comprising: A test pipeline body for flowing through a two-phase flow; A flexible conformal antenna sensor including a transmitting end and a receiving end, wherein the transmitting end and the receiving end are axially symmetrically attached and installed to the outer wall surface of the test pipeline; A vector network analyzer, whose first port is connected to the transmitting end of the flexible conformal antenna sensor, and whose second port is connected to the receiving end of the flexible conformal antenna sensor; A data processing unit connected to the vector network analyzer for processing measurement data; comprising: A data receiving module for receiving the amplitude attenuation and phase shift information of the microwave signal transmitted by the vector network analyzer; A data processing module for calculating the water content according to the amplitude attenuation and phase shift information; Wherein, the flexible conformal antenna sensor includes a flexible material dielectric substrate, a patch radiation unit, and a feeding structure, the patch radiation unit is arranged on the flexible material dielectric substrate, and the feeding structure is used for transmitting a microwave signal to the patch radiation unit or transmitting a microwave signal from the patch radiation unit.

2. The moisture content measurement system based on a flexible conformal antenna sensor according to claim 1, wherein The patch radiation unit of the flexible conformal antenna sensor is a circular patch radiation unit; the feeding structure of the flexible conformal antenna sensor is a coaxial probe feeding structure, and the coaxial probe includes an inner conductor, an outer conductor, and a filling medium.

3. The moisture content measurement system based on the flexible conformal antenna sensor according to claim 2, wherein The flexible material dielectric substrate of the flexible conformal antenna sensor uses Taconic TLX-8 material.

4. The moisture content measurement system based on a flexible conformal antenna sensor according to claim 1, characterized in that The data processing module includes: A model fitting unit for fitting measurement data according to a preset mathematical model of water content and amplitude attenuation or phase shift; A calculation unit for calculating the water content according to the fitting result.

5. The moisture content measurement system based on the flexible conformal antenna sensor according to claim 4, characterized in that, The mathematical model adopted by the model fitting unit includes: A water content model based on the amplitude of the S11 reflection coefficient; A water content model based on the amplitude of the S21 transmission coefficient; A water content model based on the phase of the S21 transmission coefficient.

6. The water content measurement method based on the flexible conformal antenna sensor uses the system described in claim 1, and is characterized in that, Including the following steps: Axially symmetrically attach and install the transmitting end and the receiving end of the flexible conformal antenna sensor to the outer wall surface of the test pipeline; Generate microwave signals at multiple frequency points through the vector network analyzer and transmit the microwave signals to the transmitting end of the flexible conformal antenna sensor; The transmitting end of the flexible conformal antenna sensor transmits the microwave signal to the two-phase flow in the test pipeline; The receiving end of the flexible conformal antenna sensor receives the microwave signal propagated through the two-phase flow and transmits the microwave signal to the vector network analyzer; The vector network analyzer receives the microwave signal and generates the amplitude attenuation and phase shift information of the microwave signal; The data processing unit calculates the water content according to the amplitude attenuation and phase shift information.

7. The moisture content measurement method according to claim 6, characterized in that, The flexible conformal antenna sensor includes a circular patch radiation unit, a rectangular patch radiation unit, an elliptical patch radiation unit, or an annular patch radiation unit.

8. The moisture content measurement method according to claim 6 or 7, characterized in that, The feeding structure of the flexible conformal antenna sensor is coaxial probe feeding, microstrip line feeding, or coupled feeding.

9. The water content measurement method according to claim 6, wherein The vector network analyzer generates microwave signals in the frequency band of 0.1 GHz to 4 GHz.

10. The moisture content measurement method according to claim 9, characterized in that, The data processing unit calculates the moisture content according to a preset mathematical model of moisture content and amplitude attenuation or phase shift. The mathematical model includes a model based on the amplitude of the S11 reflection coefficient, a model based on the amplitude of the S21 transmission coefficient, or a model based on the phase of the S21 transmission coefficient.

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