Method and system for detecting mineralization degree of oil field water injection well

Abstract

The invention discloses a mineralization degree detection method and system for a water injection well of an oil field. The method comprises the following steps: if a mineralization degree detection trigger event is detected, generating a control signal of an analog switch, and controlling the analog switch to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on a gear resistor and a conductivity detection unit; aC voltage matched with the gear resistor and AC voltage matched with the conductivity detection unit are obtained through the signal acquisition unit and are transmitted to the signal processing unit; determining the discharge time matched with each AC voltage through the signal processing unit, and sending the discharge time to the control unit; and determining the mineralization degree of the water injection solution through the control unit according to each discharge time and the pre-collected temperature of the water injection solution. According to the technical scheme, the problem that an existing salinity detection method is poor in applicability in a water injection well measurement scene is solved, salinity detection of the oil field water injection well can be achieved, meanwhile, the salinity detection accuracy is guaranteed, and the salinity detection efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to a method and system for detecting the salinity of water injection wells in oil fields. Background Technology

[0002] Currently, oil extraction is difficult and costly. Improving waterflooding efficiency and effectively reducing oil extraction costs is a long-term and arduous task for oil extraction. The implementation of waterflooding technologies such as water flooding, precision water injection, and supercritical water flooding requires precise mineralization as a basis.

[0003] However, existing mineralization detection methods, such as those based on acoustics, density, optics, and gravity, suffer from low accuracy and high cost, making them unsuitable for the measurement environment of water injection wells. Therefore, there is an urgent need for a mineralization detection method suitable for water injection wells, enabling rapid and accurate mineralization detection. Summary of the Invention

[0004] This invention provides a method and system for detecting the salinity of water injection wells in oilfields, which solves the problem of poor applicability of existing salinity detection methods in water injection well measurement scenarios. It can achieve salinity detection in water injection wells in oilfields while ensuring the accuracy of salinity detection and improving the efficiency of salinity detection.

[0005] According to one aspect of the present invention, a method for detecting the salinity of an oilfield water injection well is provided. The method is executed by a salinity detection system, which includes a conductivity detection unit, a temperature measurement unit, a control unit, an analog switch, a gear resistor, a signal acquisition unit, and a signal processing unit. The method includes:

[0006] If a mineralization detection trigger event is detected by the control unit, a control signal for the analog switch is generated, and the analog switch is controlled to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit; wherein, the magnitude of the gear resistance is controlled by the control unit based on a fuzzy algorithm;

[0007] The AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are acquired by the signal acquisition unit and transmitted to the signal processing unit.

[0008] The signal processing unit determines the discharge time for each AC voltage and sends each discharge time to the control unit.

[0009] The control unit determines the salinity of the injection solution based on each discharge time and the injection solution temperature pre-collected by the temperature measurement unit.

[0010] According to another aspect of the present invention, a mineralization detection system for oilfield water injection wells is provided, the mineralization detection system comprising a conductivity detection unit, a temperature measurement unit, a control unit, an analog switch, a gear resistor, a signal acquisition unit, and a signal processing unit;

[0011] The control unit is configured to generate a control signal for an analog switch if a mineralization detection trigger event is detected, and control the analog switch to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit; wherein, the magnitude of the gear resistance is controlled by the control unit based on a fuzzy algorithm;

[0012] The signal acquisition unit is used to acquire the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit, and transmit the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit to the signal processing unit.

[0013] The signal processing unit is used to determine the discharge time for each AC voltage matching and send each discharge time to the control unit;

[0014] The control unit is also used to determine the mineralization of the injection solution based on each discharge time and the injection solution temperature collected in advance by the temperature measurement unit.

[0015] The technical solution of this invention, if a mineralization detection trigger event is detected by the control unit, generates a control signal for an analog switch, and controls the analog switch to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit; wherein, the magnitude of the gear resistance is controlled by the control unit based on a fuzzy algorithm; the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are acquired by the signal acquisition unit, and transmitted to the signal processing unit; the signal processing unit determines the discharge time of each AC voltage match, and sends each discharge time to the control unit; the control unit determines the mineralization of the injection water solution according to each discharge time and the injection water temperature pre-acquired by the temperature measurement unit. This technical solution solves the problem of poor applicability of existing mineralization detection methods in water injection well measurement scenarios, and can achieve mineralization detection in oilfield water injection wells while ensuring the accuracy of mineralization detection and improving the efficiency of mineralization detection.

[0016] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method for detecting the salinity of an oilfield water injection well according to Embodiment 1 of the present invention;

[0019] Figure 2 This is a flowchart of a method for detecting the salinity of an oilfield water injection well according to Embodiment 2 of the present invention;

[0020] Figure 3 This is a schematic diagram of a conductivity sensor provided according to Embodiment 2 of the present invention;

[0021] Figure 4 This is a schematic diagram of the structure of a mineralization detection system for oilfield water injection wells provided in Embodiment 3 of the present invention. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be used interchangeably where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or devices. The acquisition, storage, use, and processing of data in the technical solutions of this application all comply with the relevant provisions of national laws and regulations.

[0024] Example 1

[0025] Figure 1 This document provides a flowchart of a method for detecting the salinity of water injection wells in an oilfield, as described in Embodiment 1 of the present invention. This embodiment is applicable to salinity detection scenarios in water injection wells. This method can be executed by a salinity detection system for oilfield water injection wells. Figure 1 As shown, the method includes:

[0026] S110. If a mineralization detection trigger event is detected by the control unit, a control signal for the analog switch is generated, and the analog switch is controlled to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit.

[0027] This solution can be executed by a mineralization detection system, which may include a conductivity detection unit, a temperature measurement unit, a control unit, an analog switch, a gear resistor, a signal acquisition unit, and a signal processing unit. Specifically, the conductivity detection unit detects the conductivity of the injection solution; the temperature measurement unit measures the temperature of the injection solution; the analog switch generates a bipolar square wave signal based on the control signal from the control unit; the gear resistor allows for flexible adjustment of its resistance value to accommodate the equivalent resistance values ​​of different injection solutions; the signal acquisition unit acquires the AC voltage across the conductivity detection unit and the AC voltage across the gear resistor; and the control unit controls the analog switch, acquires the discharge time output by the signal processing unit, and calculates the mineralization of the injection solution.

[0028] If the control unit detects a mineralization detection trigger event, such as pressing the start detection button or receiving a detection command, it can generate a control signal for the analog switch. Based on this control signal, the analog switch generates a bipolar square wave signal. The gear resistance and conductivity detection units can form a series circuit connected to the analog switch. The bipolar square wave signal can then act on the gear resistance and conductivity detection units, causing the series circuit formed by these units to generate alternating current.

[0029] Understandably, the equivalent resistance of different injection solutions varies. If the gear resistor differs significantly from the equivalent resistance of the injection solution—for example, if the equivalent resistance of the injection solution is 1Ω and the gear resistor is 1000Ω—the measurement error of the equivalent resistance of the injection solution will be substantial. Therefore, a gear resistor within an acceptable measurement error range needs to be matched for different injection solutions. In this solution, the size of the gear resistor can be controlled by a control unit based on a fuzzy algorithm to ensure the adaptability of the gear resistor to the equivalent resistance of the injection solution.

[0030] In a specific example, the control unit can use the conductivity and temperature of the injected water solution as input variables for a fuzzy algorithm. During the fuzzification stage, five member functions are defined for each input variable of the fuzzy algorithm, and a trapezoidal function is selected from several commonly used member functions. After fuzzification, the variables conductivity and temperature are defined using five language descriptions: "very low," "low," "medium," "high," and "very high." These language descriptions represent linear correlation functions within a preset interval and fuzzy subsets within a single bit interval [0, 1]. Based on the Mamdani fuzzy inference method, the inference rules are set according to experimental knowledge and calculation results. After fuzzy inference based on fuzzy rules, the first output value is defined using seven language descriptions: "lowest," "lower," "relatively low," "medium," "relatively high," "high," and "highest." In the defuzzification stage, the first output value is calculated based on the centroid method, according to the language descriptions and member functions. After the fuzzification stage, the range of the first output value is [0, 7]. After rounding up, the range of the first output value is an integer within [1, 7]. The first output value is used to control the magnitude of gear resistance. Corresponding to the change in the first output value, the control unit can connect a gear resistor with a matching resistance value to the series circuit of the conductivity detection unit, ensuring that the resistance value of the gear resistor matches the equivalent resistance of the measured solution and that the error is very small. If the first output value is 1, the control unit can connect the smallest gear resistor to the series circuit of the conductivity detection unit. If the first output value is 7, the control unit can connect the largest gear resistor to the series circuit of the conductivity detection unit.

[0031] S120: The AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are acquired by the signal acquisition unit, and the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are transmitted to the signal processing unit.

[0032] In this scheme, the signal acquisition unit may include two signal acquisition subunits. Each signal acquisition subunit may consist of a decoder, a buffer amplifier, and peripheral circuitry, used to acquire the AC voltage across the gear resistor and the AC voltage across the conductivity detection unit, respectively. After obtaining the AC voltage matched by the gear resistor and the AC voltage matched by the conductivity detection unit, the signal acquisition unit can transmit these two AC voltages to the signal processing unit.

[0033] S130: The signal processing unit determines the discharge time for each AC voltage and sends each discharge time to the control unit.

[0034] Understandably, the signal processing unit can include two information processing subunits, each of which can consist of an integrator and peripheral circuitry. The signal processing unit can determine the discharge time for matching the gear resistor based on the AC voltage across the gear resistor, and the discharge time for matching the conductivity detection unit based on the AC voltage across the conductivity detection unit. After obtaining the discharge time corresponding to each AC voltage, the signal processing unit can send each discharge time to the control unit for calculating the salinity of the injected water solution.

[0035] S140. The control unit determines the salinity of the injection solution based on each discharge time and the injection solution temperature collected in advance by the temperature measurement unit.

[0036] After obtaining the discharge times for the gear resistor matching and the conductivity detection unit matching, the control unit can calculate the equivalent voltage corresponding to the gear resistor based on the discharge time of the gear resistor matching, and calculate the equivalent voltage of the conductivity detection unit based on the discharge time of the conductivity detection unit matching. Based on the resistance value of the gear resistor and its corresponding equivalent voltage, the equivalent current of the series circuit formed by the gear resistor and the conductivity detection unit can be calculated. Based on the equivalent voltage of the conductivity detection unit matching and the equivalent current of the series circuit, the equivalent resistance of the conductivity detection unit can be obtained. Based on the equivalent resistance of the conductivity detection unit and the injection water temperature pre-collected by the temperature measurement unit, the salinity of the injection water can be determined.

[0037] The technical solution of this invention, if a mineralization detection trigger event is detected by the control unit, generates a control signal for an analog switch, and controls the analog switch to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit; wherein, the magnitude of the gear resistance is controlled by the control unit based on a fuzzy algorithm; the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are acquired by the signal acquisition unit, and transmitted to the signal processing unit; the signal processing unit determines the discharge time of each AC voltage match, and sends each discharge time to the control unit; the control unit determines the mineralization of the injection water solution according to each discharge time and the injection water temperature pre-acquired by the temperature measurement unit. This technical solution solves the problem of poor applicability of existing mineralization detection methods in water injection well measurement scenarios, and can achieve mineralization detection in oilfield water injection wells while ensuring the accuracy of mineralization detection and improving the efficiency of mineralization detection.

[0038] Example 2

[0039] Figure 2This is a flowchart of a method for detecting the salinity of an oilfield water injection well, provided in Embodiment 2 of the present invention. This embodiment is a refinement based on the above embodiment. Figure 2 As shown, the method includes:

[0040] S210. If a mineralization detection trigger event is detected by the control unit, a control signal for the analog switch is generated, and the analog switch is controlled to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit.

[0041] In this solution, the conductivity detection unit includes a conductivity sensor, which is a dual-electrode conductivity sensor. The internal electrode of the dual-electrode conductivity sensor is used to connect to the excitation signal, and the external electrode serves as the receiving electrode. Two symmetrical circular water outlets are provided on the external electrode to allow the injection solution to flow through. The temperature measurement unit includes a temperature sensor, which is fixed to the internal electrode of the dual-electrode conductivity sensor using thermally conductive adhesive.

[0042] Figure 3 This is a schematic diagram of a conductivity sensor provided according to Embodiment 2 of the present invention, as shown below. Figure 3 As shown, the internal electrode of the dual-electrode conductivity sensor is used to connect to the excitation signal, which is understood to be a bipolar square wave signal. The external electrode of the dual-electrode conductivity sensor can serve as the receiving electrode, and two symmetrical circular outlets are provided on the external electrode to allow the injection water solution to flow through. The temperature sensor is fixed to the internal electrode of the dual-electrode conductivity sensor with thermally conductive adhesive.

[0043] S220: The AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are acquired by the signal acquisition unit, and the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are transmitted to the signal processing unit.

[0044] S230: The signal processing unit determines the discharge time for each AC voltage and sends each discharge time to the control unit.

[0045] S240: The control unit determines the equivalent resistance of the conductivity detection unit based on each discharge time.

[0046] In this scheme, the control unit can calculate the equivalent voltage corresponding to the gear resistor based on the discharge time matched to the gear resistor, and calculate the equivalent voltage matched to the conductivity detection unit based on the discharge time matched to the conductivity detection unit. Based on the resistance value of the gear resistor and its corresponding equivalent voltage, the equivalent current of the series circuit formed by the gear resistor and the conductivity detection unit can be calculated. Finally, based on the equivalent voltage matched to the conductivity detection unit and the equivalent current of the series circuit, the equivalent resistance of the conductivity detection unit can be obtained.

[0047] S250: The control unit determines the conductivity of the injection solution based on the equivalent resistance and the injection solution temperature pre-acquired by the temperature measurement unit.

[0048] Specifically, the formula for calculating the conductivity of the injected aqueous solution can be expressed as:

[0049]

[0050] Where e represents the conductivity of the injected aqueous solution, Q represents the electrode constant of the conductivity sensor, and R... X The equivalent resistance is represented by α, the temperature coefficient of the solution at the preset standard temperature is represented by t, and the temperature of the injected aqueous solution is represented by t. cal This indicates the preset standard temperature.

[0051] The control unit can obtain the conductivity of the injected water solution by calculating the temperature compensation using the above formula.

[0052] S260. The control unit determines the mineralization of the injection solution based on the conductivity, the temperature of the injection solution, and a pre-acquired mineralization relationship model.

[0053] Having obtained the conductivity and temperature of the injected aqueous solution, as well as a pre-fitted mineralization relationship model based on experiments, the control unit can calculate the mineralization of the injected aqueous solution. Specifically, the expression for the mineralization relationship model can be expressed as:

[0054]

[0055] Where a, b, c, d and k are constant coefficients, C represents the conductivity of the injection solution, T represents the temperature of the injection solution, and S represents the mineralization of the injection solution.

[0056] It should be noted that a, b, C, d, and k can be constant coefficients obtained through experimental fitting. In a specific example, to determine the relationship between conductivity, mineralization, and temperature, a mathematical model was established to measure the relationship between mineralization and conductivity at constant temperature, and the relationship between temperature and conductivity at constant mineralization. To meet diverse mineralization measurement needs, ten potassium chloride sample solutions of different concentrations, ranging from 1 g / L to 10 g / L, were prepared and heated in an incubator. Conductivity values ​​were recorded at 20, 30, 40, 50, 60, 70, 80, and 90 °C. Each sample was measured five times at each temperature, and the average value was obtained. The results are shown in Table 1.

[0057] Table 1:

[0058]

[0059] When the temperature is constant, electrical conductivity and mineralization show a linear relationship, and the slope increases with increasing temperature. When the mineralization is constant, electrical conductivity and temperature show a linear relationship, and the slope increases with increasing mineralization. Using the above data, the relationship between electrical conductivity, mineralization, and temperature is derived, and the relationship among the three is fitted, yielding:

[0060]

[0061] After obtaining the conductivity and temperature of the injection solution, the control unit can output the mineralization of the injection solution based on the above fitting relationship.

[0062] The mineralization detection system also includes a communication unit and a host computer unit; the communication mode of the communication unit is serial communication.

[0063] After determining the mineralization of the injected aqueous solution, the method further includes:

[0064] The mineralization of the injection solution is sent to the host computer unit via the communication unit.

[0065] Understandably, the conductivity detection unit, temperature measurement unit, control unit, analog switch, gear resistor, signal acquisition unit, and signal processing unit in the salinity detection system can be deployed in the injection well for real-time salinity detection. The communication unit can include a downhole communication subunit and a surface communication subunit. The downhole communication subunit can be deployed downhole, while the surface communication subunit can be deployed on the surface to transmit the salinity data obtained from the downhole detection to the surface. The host computer unit can be deployed on the surface. After the salinity of the injection solution is determined, the communication unit can send the salinity data to the host computer unit, which can then adjust the oilfield's water injection strategy based on the salinity of the injection solution.

[0066] The technical solution of this invention, if a mineralization detection trigger event is detected by the control unit, generates a control signal for an analog switch, and controls the analog switch to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit; wherein, the magnitude of the gear resistance is controlled by the control unit based on a fuzzy algorithm; the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are acquired by the signal acquisition unit, and transmitted to the signal processing unit; the signal processing unit determines the discharge time of each AC voltage match, and sends each discharge time to the control unit; the control unit determines the mineralization of the injection water solution according to each discharge time and the injection water temperature pre-acquired by the temperature measurement unit. This technical solution solves the problem of poor applicability of existing mineralization detection methods in water injection well measurement scenarios, and can achieve mineralization detection in oilfield water injection wells while ensuring the accuracy of mineralization detection and improving the efficiency of mineralization detection.

[0067] Example 3

[0068] Figure 4 This is a schematic diagram of the structure of a salinity detection system for oilfield water injection wells provided in Embodiment 3 of the present invention. Figure 4 As shown, the mineralization detection system includes a conductivity detection unit 310, a temperature measurement unit 320, a control unit 330, an analog switch 340, a gear resistor 350, a signal acquisition unit 360, and a signal processing unit 370.

[0069] The control unit 330 is configured to generate a control signal for an analog switch if a mineralization detection trigger event is detected, and control the analog switch 340 to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistor 350 and the conductivity detection unit 310; wherein, the magnitude of the gear resistor 350 is controlled by the control unit based on a fuzzy algorithm;

[0070] The signal acquisition unit 360 is used to acquire the AC voltage matched by the gear resistor 350 and the AC voltage matched by the conductivity detection unit 310, and transmit the AC voltage matched by the gear resistor 350 and the AC voltage matched by the conductivity detection unit 310 to the signal processing unit 370.

[0071] The signal processing unit 370 is used to determine the discharge time of each AC voltage and send each discharge time to the control unit 330;

[0072] The control unit 330 is also used to determine the mineralization of the injection solution based on each discharge time and the injection solution temperature collected in advance by the temperature measurement unit 320.

[0073] In one feasible solution, optionally, the control unit 330 is specifically used for:

[0074] The equivalent resistance of the conductivity detection unit 310 is determined based on each discharge time.

[0075] The conductivity of the injection solution is determined based on the equivalent resistance and the injection solution temperature collected in advance by the temperature measurement unit 320.

[0076] The mineralization of the injection solution is determined based on the conductivity, the temperature of the injection solution, and a pre-obtained mineralization relationship model.

[0077] Based on the above scheme, optionally, the conductivity detection unit 310 includes a conductivity sensor, which is a dual-electrode conductivity sensor; wherein, the internal electrode of the dual-electrode conductivity sensor is used to connect to the excitation signal, and the external electrode is used as the receiving electrode, and two symmetrical water outlets are provided on the external electrode to allow the injection water solution to flow through.

[0078] In a preferred embodiment, the temperature measurement unit 320 includes a temperature sensor, which is fixed to the internal electrode of the dual-electrode conductivity sensor by thermally conductive adhesive.

[0079] Based on the above scheme, optionally, the mineralization detection system further includes a communication unit and a host computer unit; the communication mode of the communication unit is serial communication.

[0080] The communication unit is used for:

[0081] After determining the mineralization of the injection solution, the mineralization of the injection solution is sent to the host computer unit.

[0082] In this scheme, optionally, the expression for the mineralization relationship model is:

[0083]

[0084] Where a, b, C, d and k are constant coefficients, C represents the conductivity of the injection solution, T represents the temperature of the injection solution, and S represents the mineralization of the injection solution.

[0085] In this embodiment, optionally, the formula for calculating the conductivity of the injected aqueous solution is expressed as follows:

[0086]

[0087] Where e represents the conductivity of the injected aqueous solution, Q represents the electrode constant of the conductivity sensor, and R... X The equivalent resistance is represented by α, the temperature coefficient of the solution at the preset standard temperature is represented by t, and the temperature of the injected aqueous solution is represented by t. cal This indicates the preset standard temperature.

[0088] The mineralization detection system for oilfield water injection wells provided in this embodiment of the invention can execute the mineralization detection method for oilfield water injection wells provided in any embodiment of the invention, and has the corresponding beneficial effects of executing the method.

Claims

1. A method for detecting the salinity of water injection wells in oilfields, characterized in that, The method is executed by a mineralization detection system, which includes a conductivity detection unit, a temperature measurement unit, a control unit, an analog switch, a gear resistor, a signal acquisition unit, and a signal processing unit; the method includes: If a mineralization detection trigger event is detected by the control unit, a control signal for the analog switch is generated, and the analog switch is controlled to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit; wherein, the magnitude of the gear resistance is controlled by the control unit based on a fuzzy algorithm; The AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit are acquired by the signal acquisition unit and transmitted to the signal processing unit. The signal processing unit determines the discharge time for each AC voltage and sends each discharge time to the control unit. The control unit determines the salinity of the injection solution based on each discharge time and the injection solution temperature pre-collected by the temperature measurement unit.

2. The method according to claim 1, characterized in that, The process of determining the mineralization of the injection solution by the control unit based on each discharge time and the injection solution temperature pre-collected by the temperature measurement unit includes: The equivalent resistance of the conductivity detection unit is determined by the control unit based on each discharge time. The control unit determines the conductivity of the injection solution based on the equivalent resistance and the injection solution temperature pre-collected by the temperature measurement unit. The control unit determines the mineralization of the injected water solution based on the conductivity, the temperature of the injected water solution, and a pre-acquired mineralization relationship model.

3. The method according to claim 1, characterized in that, The conductivity detection unit includes a conductivity sensor, which is a dual-electrode conductivity sensor. The internal electrode of the dual-electrode conductivity sensor is used to connect to the excitation signal, and the external electrode is used as the receiving electrode. Two symmetrical circular water outlets are provided on the external electrode to allow the injection water solution to flow through.

4. The method according to claim 3, characterized in that, The temperature measurement unit includes a temperature sensor, which is fixed to the internal electrode of the dual-electrode conductivity sensor by thermally conductive adhesive.

5. The method according to claim 4, characterized in that, The mineralization detection system also includes a communication unit and a host computer unit; the communication mode of the communication unit is serial communication. After determining the mineralization of the injected aqueous solution, the method further includes: The mineralization of the injection solution is sent to the host computer unit via the communication unit.

6. The method according to claim 3, characterized in that, The expression for the mineralization relationship model is as follows: Where a, b, C, d and k are constant coefficients, C represents the conductivity of the injection solution, T represents the temperature of the injection solution, and S represents the mineralization of the injection solution.

7. The method according to claim 3, characterized in that, The formula for calculating the conductivity of the injected aqueous solution is as follows: Where e represents the conductivity of the injected aqueous solution, Q represents the electrode constant of the conductivity sensor, and R... X The equivalent resistance is represented by α, the temperature coefficient of the solution at the preset standard temperature is represented by t, and the temperature of the injected aqueous solution is represented by t. cal This indicates the preset standard temperature.

8. A salinity detection system for oilfield water injection wells, characterized in that, The mineralization detection system includes a conductivity detection unit, a temperature measurement unit, a control unit, an analog switch, a gear resistor, a signal acquisition unit, and a signal processing unit. The control unit is configured to generate a control signal for an analog switch if a mineralization detection trigger event is detected, and control the analog switch to generate a bipolar square wave signal according to the control signal, so that the bipolar square wave signal acts on the gear resistance and conductivity detection unit; wherein, the magnitude of the gear resistance is controlled by the control unit based on a fuzzy algorithm; The signal acquisition unit is used to acquire the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit, and transmit the AC voltage matched by the gear resistance and the AC voltage matched by the conductivity detection unit to the signal processing unit. The signal processing unit is used to determine the discharge time for each AC voltage matching and send each discharge time to the control unit; The control unit is also used to determine the mineralization of the injection solution based on each discharge time and the injection solution temperature collected in advance by the temperature measurement unit.

9. The system according to claim 8, characterized in that, The control unit is specifically used for: The equivalent resistance of the conductivity detection unit is determined based on each discharge time. The conductivity of the injection solution is determined based on the equivalent resistance and the injection solution temperature collected in advance by the temperature measurement unit. The mineralization of the injection solution is determined based on the conductivity, the temperature of the injection solution, and a pre-obtained mineralization relationship model.

10. The system according to claim 8, characterized in that, The conductivity detection unit includes a conductivity sensor, which is a dual-electrode conductivity sensor. The internal electrode of the dual-electrode conductivity sensor is used to connect to the excitation signal, and the external electrode serves as the receiving electrode. Two symmetrical water outlets are provided on the external electrode to allow the injection water solution to flow through.

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