A method and device for determining the water content of crude oil in a field oil pool

Abstract

The invention discloses a method and device for determining the water content of crude oil in a field oil pool. The method comprises a winding capacitive sensor and an AD conversion unit, a temperature sensor, a synchronous toothed belt and a support frame thereof, a stepping motor and a driver, a transmission cable and a main control unit. The main control unit controls the winding capacitive sensor to automatically rise from the bottom of the oil pool to the height of the oil pool liquid surface. Each rising height is the height of the winding capacitive sensor. At each height position, the temperature and the capacitance value of the capacitive sensor at the position are read. A three-dimensional data table lookup is performed on the temperature and the capacitance to obtain the water content at each height point, and a water content distribution curve in the oil pool is obtained. The water content distribution curve is integrated to obtain the total water content of the oil pool. The table calibration data is the capacitance value measured by a laboratory under the condition of accurately controlling the temperature and the water content. A quadratic polynomial linear interpolation method is selected when the three-dimensional data table lookup is performed to obtain an accurate water content distribution curve at the temperature.

Description

Technical field:

[0001] The invention belongs to the field of petrochemical instruments, and in particular relates to a method and a device for determining the water content of crude oil in a field oil pool. Background technology:

[0002] The water content of oil well production has important guiding significance for the development of oil fields, and directly affects the management of crude oil production, metering, gathering, transportation, purification and other links. Therefore, accurate and timely measurement of the water content of crude oil in oil pools or oil tanks can reflect the working status of oil wells, and play an important role in reducing energy consumption and costs for management departments and realizing automated management of oil fields.

[0003] At present, in addition to manual testing methods, the online detection methods for analyzing and detecting the water content of oil well production fluid in oil fields mainly include density meter method, gamma ray method, capacitance method, short wave method, radio frequency method, etc. Although these different forms of crude oil water content testing instruments have achieved certain results, due to the extremely complex composition of oil well production fluid, the presence of mechanical impurities, colloids, wax deposition, scaling and corrosion factors to varying degrees, their stability, accuracy, reliability and cost cannot meet the production requirements of China's oil fields, and the field environment is more complex than the laboratory environment, and the stability requirements are higher. Therefore, in view of the characteristics of my country's crude oil production, it is of great social significance and economic value to study the technology and method for detecting the water content of crude oil and develop a technology suitable for detecting the water content of crude oil in my country. Therefore, the present invention proposes a method and device for determining the water content of crude oil in a field oil pool. Summary of the invention:

[0004] The purpose of the present invention is to provide a method and device for determining the water content of crude oil in a field oil pool in order to solve the above-mentioned problem, thereby overcoming the shortcomings of the prior art.

[0005] In order to solve the above problems, the present invention provides a technical solution:

[0006] A device for measuring the water content of crude oil in a field oil pool comprises a wound capacitive sensor and an AD conversion unit, a temperature sensor, a synchronous toothed belt and a support frame thereof, a stepper motor and a driver, a transmission cable, and a master control unit. The master control unit is electrically connected to the stepper motor and the driver via a transmission cable. The stepper motor and the driver are connected to the wound capacitive sensor and the AD conversion unit and the temperature sensor via a synchronous toothed belt and a support frame. The wound capacitive sensor and the AD conversion unit and the temperature sensor are electrically connected.

[0007] A method for measuring the water content of crude oil in a field oil pool, including a hardware system and a software system for measuring the water content of crude oil in a field oil pool. The hardware system includes a main control unit, a motion unit, a sensor unit, and a data acquisition unit. The software system for the method and device for measuring the water content of crude oil in a field oil pool includes a three-dimensional data step-by-step look-up table algorithm and a total water content algorithm. The main control unit is an industrial computer, a display, a human-computer interaction unit, etc. The human-computer interaction unit uses a 15-inch non-touch industrial display screen.

[0008] Preferably, the motion unit is an industrial control machine, a motion control card, a motor driver, a motor, and a sensor unit. The motion control card is selected as the Googol GTS-400, and the model of the industrial control machine is Advantech IPC-610L-6011.

[0009] Preferably, the sensor unit is a wound capacitance sensor and a temperature sensor. The wound capacitance sensor is composed of a slender wire and a hollow insulating cylinder. The wound capacitance sensor is formed by winding a slender wire with a diameter of 1.5 mm around a hollow insulating cylinder with a diameter of 15 mm and a length of 100 mm to form a double helix structure. The hollow insulating cylinder has a diameter of 15 mm and a length of 100 mm. The temperature sensor is a sensor with a working temperature range of -40°C to 100°C. The temperature sensor is installed inside the hollow insulating cylinder of the wound capacitance sensor, and the temperature sensor probe and the cylinder end face are in the same plane.

[0010] Preferably, the hardware system includes a capacitance-voltage conversion circuit and an AD conversion unit. The capacitance-voltage conversion circuit is a capacitance signal linear conversion voltage output interface integrated circuit and has a built-in temperature sensor. The AD conversion unit is a voltage acquisition module. The capacitance signal linear conversion voltage output interface integrated circuit uses the CAV444 integrated circuit.

[0011] Preferably, the specific operation steps of the three-dimensional data step-by-step look-up table algorithm are as follows:

[0012] The first step is to obtain the corresponding curve of water content and capacitance value at the current temperature:

[0013] Suppose the temperature x and the capacitance value b are measured in the current state. First, obtain the distribution curve of the relationship between water content and capacitance value at the current temperature, and then obtain the water content from the current capacitance value. Suppose Xi < x < Xi+1 < Xi+2, then among the capacitance values B{b0, b1, b2,..., bm} corresponding to different water contents at the temperature x:

[0014] 1. The capacitance values Bi {Bi0, Bi1, Bi2, …, Bim} of the wound capacitive sensor measured at different water contents at temperature Xi, the capacitance values Bi+1 {B(i+1)0, B(i+1)1, B(i+1)2, …, B(i+1)m} of the wound capacitive sensor measured at different water contents at temperature Xi+1, and the capacitance values Bi+2 {B(i+2)0, B(i+2)1, B(i+2)2, …, B(i+2)m} of the wound capacitive sensor measured at different water contents at temperature Xi+2;

[0015] 2. Taking the capacitance value corresponding to the water content at the 0th point as an example, the capacitance value at temperature Xi is Bi0, the capacitance value at temperature Xi+1 is B(i+1)0, and the capacitance value at temperature Xi+2 is B(i+2)0. The quadratic polynomial B = c1X2 + d1X + e1 is obtained by fitting the three data points (Xi, Bi0), (Xi+1, B(i+1)0), and (Xi+2, B(i+2)0), where c1, d1, and e1 are constants. Substituting the measured temperature x in the current state, b0 in the capacitance values B corresponding to different water contents at temperature x is obtained. Similarly, the capacitance values corresponding to the water contents at other points in the capacitance values B corresponding to different water contents at the current temperature x can be obtained.

[0016] The second step is to obtain the water content corresponding to the current capacitance value

[0017] After obtaining the capacitance values B {b0, b1, b2, …, bm} corresponding to different water contents at the current temperature x in the first step, the actually measured b is looked up in a table. Since the calibration range in the laboratory cannot control high-precision continuity, there will be such a situation. Therefore, it is necessary to fit a curve for the set of corresponding points between the water content and the capacitance value. According to the established industry experience, as the water content increases, the corresponding capacitance value increases monotonically. Therefore, a quadratic polynomial curve is fitted with three points close to the current capacitance value to ensure the effectiveness and accuracy of the data. The specific calculation is as follows:

[0018] 1. Looking up the capacitance value b in the table gives: bj < b < bj+1 < j+2, where j is a known value of the water content during laboratory calibration;

[0019] 2. The quadratic polynomial b’ = c2J2 + d2J + e2 is obtained by fitting the three data points (j, bj), (j+1, bj+1), and (j+2, j+2), where c2, d2, and e2 are constants, J is the independent variable water content in the current interval, and b’ is the dependent variable capacitance value in the current interval. Substituting the measured b in the current state, the water content corresponding to the current state is obtained.

[0020] Preferably, the specific operation steps of the total water content algorithm are:

[0021] 1. The sensor length is 100mm. The capacitance value obtained at this point is the capacitance value corresponding to the water content within the 100mm thickness range. In the oil pool with a depth of L, the measured data is a total of L / 100 discrete data points with an interval of 100mm. Each discrete point corresponds to the water content of 100mm thickness in the oil pool. Considering that the distribution of crude oil and water in the oil pool is uniform and continuous from top to bottom;

[0022] 2. Perform curve fitting on the discrete point set to get closer to the actual situation of oil-water distribution in the oil pool. The specific algorithm is as follows: Step 1: Curve fitting. For the water content of each discrete point MC{MC1, MC2, MC3, ..., MCN} (where N is equal to L / 100, rounded down), a fitting curve is adopted. The principle of consistent distribution of adjacent points is adopted. A quadratic polynomial is fitted for every three points of MC (to ensure that the fitting algorithm is consistent with the table lookup algorithm) to obtain H=F(h), where h is the depth in the oil pool and H is the water content corresponding to the depth h; Step 2: Curve integration. Integrate the obtained H=F(h) to obtain the total water content distribution curve of the entire oil pool. Finally, the average is calculated to obtain the average water content in the oil pool.

[0023] Preferably, the operating steps of the method for determining the water content of crude oil in the field oil pool are:

[0024] Step 1: Calibrate the relationship between moisture content and capacitance value at different temperatures in the laboratory. Since the three-dimensional data step-by-step table lookup algorithm and the total moisture content algorithm in this algorithm have been verified by experiments to achieve a result accuracy that is more than twice that of laboratory calibration in actual measurement, the laboratory calibration points can be selected according to actual conditions.

[0025] Step 2: Start the measuring device, initialize each unit, and move the sensor to the bottom of the oil pool;

[0026] Step 3: The sensor unit collects data on the current state and determines whether the data is normal or not, and continues to collect data if it rises;

[0027] Step 4: If the rise continues, repeat step 3 after rising 100mm, and proceed to the next step if the rise stops;

[0028] Step 5: After data collection is completed, a three-dimensional data step-by-step table lookup algorithm is performed on each state point to obtain the water content at each height point in the oil pool.

[0029] Step 6: Complete the total water content algorithm for the water content at each height point in the oil pool to obtain the average water content of the oil pool.

[0030] Beneficial effects of the present invention:

[0031] The main control unit of the present invention controls the winding capacitive sensor to automatically rise from the bottom of the oil pool to the height of the oil pool liquid level. Each rising height is the height of the winding capacitive sensor. At each height position, the temperature and the capacitance value of the capacitive sensor at that position are read. A three-dimensional data table lookup is performed on the temperature and capacitance to obtain the water content at each height point. A quadratic polynomial is fitted to the water content of each three adjacent points to obtain a water content distribution curve in the oil pool. The water content distribution curve is integrated to obtain the total water content of the oil pool. The table calibration data is the capacitance value measured by the laboratory under the condition of precise control of the temperature and water content. The quadratic polynomial linear interpolation method is selected when the three-dimensional data table lookup is performed to obtain an accurate water content distribution curve at the temperature. Description of the drawings:

[0032] For ease of explanation, the present invention is described in detail with reference to the following specific implementations and the accompanying drawings.

[0033] Figure 1 This is a schematic structural diagram of a device for measuring the water content of crude oil in a field oil pool according to one embodiment of the present invention;

[0034] Figure 2 A schematic diagram of a capacitive signal linear conversion voltage output interface integrated circuit according to an embodiment of the present invention;

[0035] Figure 3 A schematic diagram of the operation of an AD conversion unit according to an embodiment of the present invention;

[0036] Figure 4 The present invention is a flow chart of a method for determining the water content of crude oil in a field oil pool according to one embodiment of the present invention.

[0037] In the figure: 1. Wrap-around capacitive sensor and AD conversion unit; 2. Temperature sensor; 3. Synchronous toothed belt and its support frame; 4. Stepper motor and driver; 5. Transmission cable; 6. Master control unit. Specific implementation method:

[0038] like Figure 1-4As shown, this specific embodiment adopts the following technical scheme: a device for determining the water content of crude oil in a field oil pool, comprising a wound capacitive sensor and AD conversion unit 1, a temperature sensor 2, a synchronous toothed belt and its support frame 3, a stepper motor and a driver 4, a transmission cable 5, and a main control unit 6. The main control unit 6 is electrically connected to the stepper motor and the driver 4 through the transmission cable 5. The stepper motor and the driver 4 are connected to the wound capacitive sensor and AD conversion unit 1 and the temperature sensor 2 through the synchronous toothed belt and its support frame 3. The wound capacitive sensor and AD conversion unit 1 and the temperature sensor 2 are electrically connected. The temperature sensor 2 adopts a PT100 thermal resistor temperature sensor. The AD conversion unit in the wound capacitive sensor and AD conversion unit 1 adopts a WP3066ADAM acquisition module. The stepper motor and the driver 4 selects a 2S420240 stepper motor and its driver.

[0039] A method for determining the water content of crude oil in a field oil pool comprises a hardware system and a software system for the method for determining the water content of crude oil in a field oil pool. The hardware system comprises a main control unit, a motion unit, a sensor unit, and a data acquisition unit. The software system of the method for determining the water content of crude oil in a field oil pool and the device comprises a three-dimensional data step-by-step table lookup algorithm and a total water content algorithm. The main control unit is an industrial computer and a display, a human-computer interaction unit, etc. The human-computer interaction unit adopts a 15-inch non-touch industrial display screen, an industrial computer and a display, a human-computer interaction unit, etc., which are responsible for the control of start, end and termination as well as data processing and display.

[0040] Among them, the motion unit is an industrial control machine, a motion control card, a motor driver, a motor and a sensor unit. The motion control card is Googol GTS-400, and the model of the industrial control machine is IPC-610L-6011. The industrial control machine sends the motion command to the motion control card. After parsing the motion command, the motion control card outputs a pulse to the motor driver. The motor driver drives the motor to rotate, and drives the sensor unit to move up and down through the synchronous belt.

[0041] Among them, the sensor unit is a wound capacitive sensor and a temperature sensor 2. The wound capacitive sensor is composed of a slender wire and a hollow insulating cylinder. The wound capacitive sensor is composed of a slender wire with a diameter of 1.5 mm wound around a hollow insulating cylinder with a diameter of 15 mm and a length of 100 mm to form a double helix structure. The temperature sensor 2 is a sensor with an operating temperature range of -40°C to 100°C. The temperature sensor 2 is installed in the hollow insulating cylinder of the wound capacitive sensor. The probe of the temperature sensor 2 is located in the same plane as the end face of the cylinder to ensure the accuracy of the measurement.

[0042] Among them, the hardware system includes a capacitance-voltage conversion circuit and an AD conversion unit. The capacitance-voltage conversion circuit is a capacitive signal linear conversion voltage output interface integrated circuit with a built-in temperature sensor. The AD conversion unit is a voltage acquisition module. The capacitive signal linear conversion voltage output interface integrated circuit adopts the CAV444 integrated circuit. The capacitive signal linear conversion voltage output interface integrated circuit has the functions of signal acquisition, processing, and differential voltage output, and also has a built-in temperature sensor. The capacitance signal ΔCM(=CM,max - CM,min) and the output voltage are in a linear relationship. Here, CM,min is the background capacitance of the capacitance sensor CM, and CM,max is the maximum capacitance value of the capacitance sensor. The measured capacitance (sensor) serves as the capacitor of the built-in measurement oscillator, and by charging and discharging it, an oscillation period is generated. This oscillation period is linearly related to the size of the measured capacitance. Through a frequency / voltage conversion circuit and a low-pass filter, a DC voltage signal is finally output, and through an output stage with adjustable zero point and full scale, the desired voltage signal output value is obtained. The output voltage and the reference voltage VREF(2.5V) form a differential voltage output.

[0043] Among them, the specific operation steps of the three-dimensional data step-by-step look-up algorithm are as follows:

[0044] The first step is to obtain the corresponding curve of water content and capacitance value at the current temperature:

[0045] Assume that the measured temperature x and capacitance value b are obtained in the current state. First, the distribution curve of the relationship between water content and capacitance value at the current temperature is obtained, and then the water content is obtained from the current capacitance value. Assume Xi < x < Xi+1 < Xi+2. Among the capacitance values B{b0, b1, b2, …, bm} corresponding to different water contents at temperature x:

[0046] 1. The capacitance values Bi{Bi0, Bi1, Bi2, …, Bim} of the wound capacitance sensor measured at different water contents at temperature Xi, the capacitance values Bi+1{B(i+1)0, B(i+1)1, B(i+1)2, …, B(i+1)m} of the wound capacitance sensor measured at different water contents at temperature Xi+1, and the capacitance values Bi+2{B(i+2)0, B(i+2)1, B(i+2)2, …, B(i+2)m} of the wound capacitance sensor measured at different water contents at temperature Xi+2;

[0047] 2. Taking the capacitance value corresponding to the water content at the 0th point as an example, the capacitance value at temperature Xi is Bi0, the capacitance value at temperature Xi+1 is B(i+1)0, and the capacitance value at temperature Xi+2 is B(i+2)0. From the data points Xi, Bi0, Xi+1, B(i+1)0, Xi+2, B(i+2)0, a quadratic polynomial is fitted for three points to obtain B = c1X2 + d1X + e1, where c1, d1, and e1 are constants. Substituting the measured temperature x in the current state, the capacitance value b0 corresponding to different water contents at temperature x is obtained. Similarly, the capacitance values corresponding to the water contents at other points in B corresponding to different water contents at the current temperature x can be obtained.

[0048] Step 2. Obtain the water content corresponding to the current capacitance value

[0049] After obtaining the capacitance values B{b0, b1, b2, …, bm} corresponding to different water contents at the current temperature x in the first step, look up the actual measured b. Since it is impossible to control high-precision continuity in the laboratory calibration range, there will be such a situation. Therefore, it is necessary to fit a curve for the set of corresponding points of water content and capacitance value. From the established industry experience, it is known that as the water content increases, the corresponding capacitance value increases monotonically. Therefore, take three points with similar current capacitance values to fit a quadratic polynomial curve to ensure the effectiveness and accuracy of the data. The specific calculation is as follows:

[0050] 1. Looking up the capacitance value b gives: bj < b < bj+1 < j+2, where j is a known value of the water content during laboratory calibration;

[0051] 2. From the data points j, bj, j+1, bj+1, j+2, j+2, a quadratic polynomial is fitted for three points to obtain b’ = c2J2 + d2J + e2, where c2, d2, and e2 are constants, J is the independent variable water content in the current interval, and b’ is the dependent variable capacitance value in the current interval. Substituting the measured b in the current state, the water content corresponding to the current state is obtained.

[0052] Among them, the specific operation steps of the total water content algorithm are as follows:

[0053] 1. The length of the sensor is 100 mm. The capacitance value obtained at this point is the capacitance value corresponding to the water content within the thickness of 100 mm. In an oil pool with a depth of L, the measured data are a total of L / 100 discrete data points at intervals of 100 mm. Each discrete point corresponds to the water content within a thickness of 100 mm in the oil pool. Given that the distribution of crude oil and water in the oil pool is evenly distributed and continuous up and down;

[0054] 2. Perform curve fitting on the discrete point set to get closer to the actual situation of oil-water distribution in the oil pool. The specific algorithm is as follows: Step 1: Curve fitting. For the water content of each discrete point MC{MC1, MC2, MC3, ..., MCN}, where N is equal to L / 100, round down the fitting curve. Based on the principle of consistent distribution of adjacent points, perform quadratic polynomial fitting on every three points of MC to ensure that the fitting algorithm is consistent with the table lookup algorithm, and obtain H=Fh, where h is the depth in the oil pool and H is the water content corresponding to the depth h; Step 2: Curve integration. Integrate the obtained H=Fh to obtain the total water content distribution curve of the entire oil pool. Finally, calculate the average value to obtain the average water content in the oil pool.

[0055] The operating steps of the method for determining the water content of crude oil in the field oil pool are as follows:

[0056] Step 1: Calibrate the relationship between moisture content and capacitance value at different temperatures in the laboratory. Since the three-dimensional data step-by-step table lookup algorithm and the total moisture content algorithm in this algorithm can achieve a result accuracy more than twice that of the laboratory calibration accuracy in actual measurement, the laboratory calibration points can be selected according to the actual situation.

[0057] Step 2: Start the measuring device, initialize each unit, and move the sensor to the bottom of the oil pool;

[0058] Step 3: The sensor unit collects data on the current state and determines whether the data is normal or not, and continues to collect data if it rises;

[0059] Step 4: If the rise continues, repeat step 3 after rising 100mm, and proceed to the next step if the rise stops;

[0060] Step 5: After data collection is completed, a three-dimensional data step-by-step table lookup algorithm is performed on each state point to obtain the water content at each height point in the oil pool.

[0061] Step 6: Complete the total water content algorithm for the water content at each height point in the oil pool to obtain the average water content of the oil pool.

[0062] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which shall fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A device for measuring the water content of crude oil in a field oil pool, characterized in that: It includes a hardware system and a software system that adopt the method for measuring the water content of crude oil in a field oil pool. The hardware system includes a main control unit, a motion unit, a sensor unit, and a data acquisition unit. The software system that adopts the method for measuring the water content of crude oil in a field oil pool includes a three-dimensional data step-by-step look-up table algorithm and a total water content algorithm. The main control unit is an industrial computer, a display, and a human-computer interaction unit. The human-computer interaction unit uses a 15-inch non-touch industrial display screen; The specific operation steps of the three-dimensional data step-by-step look-up table algorithm are as follows: The first step is to obtain the corresponding curve of water content and capacitance value at the current temperature: Suppose the measured temperature x and capacitance value b in the current state. First, obtain the distribution curve of the relationship between water content and capacitance value at the current temperature, and then obtain the water content from the current capacitance value. Suppose Xi < x < Xi+1 < Xi+2, then among the capacitance values B{b0, b1, b2, …, bm} corresponding to different water contents at temperature x:

1. The capacitance values Bi{Bi0, Bi1, Bi2, …, Bim} of the wound capacitance sensor measured at different water contents at temperature Xi, the capacitance values Bi+1{B(i+1)0, B(i+1)1, B(i+1)2, …, B(i+1)m} of the wound capacitance sensor measured at different water contents at temperature Xi+1, and the capacitance values Bi+2{B(i+2)0, B(i+2)1, B(i+2)2, …, B(i+2)m} of the wound capacitance sensor measured at different water contents at temperature Xi+2; 2. Taking the capacitance value corresponding to the water content at the 0th point as an example, the capacitance value at temperature Xi is Bi0, the capacitance value at temperature Xi+1 is B(i+1)0, and the capacitance value at temperature Xi+2 is B(i+2)0. Fit a quadratic polynomial from the three data points (Xi, Bi0), (Xi+1, B(i+1)0), (Xi+2, B(i+2)0) to get B = c1X2 + d1X + e1, where c1, d1, and e1 are constants. Substitute the measured temperature x in the current state to obtain b0 among the capacitance values B corresponding to different water contents at temperature x. Similarly, the capacitance values corresponding to the water contents at other points among the capacitance values B corresponding to different water contents at the current temperature x can be obtained; The second step is to obtain the water content corresponding to the current capacitance value: After obtaining the capacitance values ​​B{b0, b1, b2, ..., bm} corresponding to different water contents at the current temperature x in the first step, the actual measured b is looked up in the table. Since the laboratory calibration interval cannot control the continuity of high precision, there will be Therefore, it is necessary to fit the curve of the corresponding point set of water content and capacitance value. As the water content increases, the corresponding capacitance value increases monotonically. Therefore, three points with similar current capacitance values ​​are taken to fit the quadratic polynomial curve. The specific calculation is as follows:

1. Look up the capacitance value b to get: bj < b < bj+1 < j+2, where j is a known value of the water content during laboratory calibration; 2. Fit a quadratic polynomial from the three data points (j, bj), (j+1, bj+1), (j+2, j+2) to get b’ = c2J2 + d2J + e2, where c2, d2, and e2 are constants, J is the independent variable water content in the current interval, b’ is the dependent variable capacitance value in the current interval. Substitute the measured b in the current state to obtain the water content corresponding to the current state; The specific operation steps of the total water content algorithm are as follows:

1. The sensor length is 100mm. The capacitance value obtained at this point is the capacitance value corresponding to the water content within the 100mm thickness range. In the oil pool with a depth of L, the measured data is a total of L / 100 discrete data points with an interval of 100mm. Each discrete point corresponds to the water content of 100mm thickness in the oil pool. Considering that the distribution of crude oil and water in the oil pool is uniform and continuous from top to bottom; 2. Perform curve fitting on the discrete point set to get closer to the actual distribution of oil and water in the oil pool. The specific algorithm is as follows: Step 1: Curve fitting. For each discrete point water content MC{MC1, MC2, MC3, ..., MCN} (where N is equal to L / 100, rounded down), a fitting curve is obtained. Based on the principle that the distribution law of adjacent points is consistent, a quadratic polynomial is fitted for every three points of MC (ensuring that the fitting algorithm is consistent with the table lookup algorithm), and H=F(h) is obtained, where h is the depth in the oil pool and H is the water content corresponding to the depth h; Step 2: Curve integration: Integrate the obtained H=F(h) to obtain the total water content distribution curve of the entire oil pool, and finally calculate the average value to obtain the average water content in the oil pool.

2. A device for measuring water content of crude oil in a field oil pool according to claim 1, characterized in that: The motion unit includes an industrial control machine, a motion control card, a motor driver, a motor and a sensor unit. The motion control card is Googol GTS-400, and the model of the industrial control machine is IPC-610L-6011.

3. The device for measuring the water content of crude oil in a field oil pool according to claim 1, characterized in that: The sensor unit is a wound capacitive sensor and a temperature sensor (2). The wound capacitive sensor is composed of a slender wire and a hollow insulating cylinder. The wound capacitive sensor is formed by winding a slender wire with a diameter of 1.5 mm around a hollow insulating cylinder with a diameter of 15 mm and a length of 100 mm to form a double helix structure. The temperature sensor (2) is a sensor with an operating temperature range of -40°C to 100°C. The temperature sensor (2) is installed in the hollow insulating cylinder of the wound capacitive sensor. The probe of the temperature sensor (2) and the end face of the cylinder are located in the same plane.

4. A device for measuring water content of crude oil in a field oil pool according to claim 1, characterized in that: The hardware system includes a capacitance-to-voltage conversion circuit and an AD conversion unit. The capacitance-to-voltage conversion circuit is a capacitive signal linear conversion voltage output interface integrated circuit with a built-in temperature sensor. The AD conversion unit is a voltage acquisition module. The capacitance signal linear conversion voltage output interface integrated circuit adopts a CAV444 integrated circuit.

5. The device for measuring the water content of crude oil in a field oil pool according to claim 1, characterized in that: The operating steps of the method for determining the water content of crude oil in the field oil pool are as follows: Step 1: Calibrate the relationship between moisture content and capacitance value at different temperatures in the laboratory. The laboratory calibration points can be selected according to the actual situation; Step 2: Start the measuring device, initialize each unit, and move the sensor to the bottom of the oil pool; Step 3: The sensor unit collects data on the current state and determines whether the data is normal or not, and continues to collect data if it rises; Step 4: If the rise continues, repeat step 3 after rising 100mm, and proceed to the next step if the rise stops; Step 5: After data collection is completed, a three-dimensional data step-by-step table lookup algorithm is performed on each state point to obtain the water content at each height point in the oil pool; Step 6: Complete the total water content algorithm for the water content at each height point in the oil pool to obtain the average water content of the oil pool.

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