System and method for detecting working fluid level of oil well

Abstract

The invention relates to an oil well working fluid level detection system and method.A plurality of conductive elements and cable assemblies are arranged between an oil pipe and a sleeve, a power source and a current detection device are arranged on a well, and every two adjacent conductive elements are electrically connected through petroleum by means of the conductivity of the petroleum to form a circuit loop; the depth of the working fluid level affects the number of the conductive elements connected into the circuit, the total resistance in the circuit is changed, the corresponding working fluid level depth can be obtained by detecting the current value of the circuit, and detection of the working fluid level of an oil well is achieved.

Description

Technical Field

[0001] This application relates to the technical field of oil extraction, and in particular to an oil well flowing fluid level detection system and method. Background Art

[0002] The flowing fluid level of an oil well (i.e., the dynamic height of the liquid column in the wellbore during the oil production process) is a core parameter in oilfield production management. Whether it is too high or too low, it will cause systematic risks, directly affecting the pumping efficiency, energy consumption control, and well control safety. The change in the flowing fluid level of an oil well reflects the oilfield's liquid supply capacity and the coordination status of wellbore supply and drainage. Although there are various existing monitoring technologies, they all have significant limitations:

[0003] The currently commonly used measurement method is the ultrasonic measurement method. Its principle is to emit sound waves into the annulus between the tubing and the casing, and calculate the fluid level depth by receiving the time difference of the liquid level reflection wave. This method is easily affected by wellbore noise (such as air flow, collar reflection), resulting in a signal-to-noise ratio of the liquid level echo lower than 20% and a misjudgment rate exceeding 30%. Another method is the direct measurement method, which installs measurement devices such as sensors and pressure gauges downhole to directly obtain the flowing fluid level data. Although this method has higher accuracy, it is complex to install and costly, and is prone to failure in high-temperature wells (greater than 150°C). In summary, both methods are difficult to achieve real-time, economical, efficient, and intelligent measurement of the flowing fluid level depth, which is not conducive to the intelligent and informatized development of oilfields.

[0004] Therefore, we propose an oil well flowing fluid level detection system and method. Summary of the Invention

[0005] This application aims at the above-mentioned drawbacks in the existing technology and provides an oil well flowing fluid level detection system and method.

[0006] The technical solution adopted in this application is as follows:

[0007] An oil well flowing fluid level detection system includes a tubing 1 and a casing 2. The flowing fluid level is located between the tubing 1 and the casing 2. The oil well flowing fluid level detection system further includes a plurality of conductive elements 3, a cable assembly 4, a power supply, and a current detection device;

[0008] The conductive elements 3 are distributed along the axial direction of the tubing 1 and are at a fixed height between the tubing 1 and the casing 2;

[0009] The cable assembly 4 includes two separated main cable lines 401. The upper ends of the two main cable lines 401 are respectively connected to the positive and negative poles of the power supply. The lower ends of the two main cable lines 401 are connected to the conductive elements 3 through a plurality of cable branches 402. Each conductive element 3 is only connected to one cable branch 402; the current detection device is used to detect the current value of the main cable line 401.

[0010] Its further technical solution includes that the connection mode between the cable assembly 4 and the conductive element 3 is as follows: two axially adjacent conductive elements 3 are connected to different cable branches 402 corresponding to the cable main lines 401.

[0011] Its further technical solution includes that the connection mode between the cable assembly 4 and the conductive element 3 is as follows: one cable main line 401 is connected to the lowermost conductive element 3, and the other cable main line 401 is connected to the remaining conductive elements 3 through several cable branches 402.

[0012] Its further technical solution includes that the oil well fluid level detection system further includes a protection resistor, which is connected in series to one of the cable main lines 401 and is in parallel with a voltmeter.

[0013] Its further technical solution includes that the conductive element 3 is arranged in a semi-open insulation box 5 and is fixed at a fixed height of the tubing 1 through the insulation box 5; the distance between the insulation box 5 and the casing 2 is less than the distance between the conductive element 3 and the casing 2.

[0014] The technical solution adopted by the present invention further includes:

[0015] An oil well fluid level detection method includes:

[0016] Obtain the current value of the cable main line 401 and the well condition parameters of the oil well, determine the number of conductive elements 3 connected to the circuit based on the current value and the well condition parameters, and determine the fluid level depth based on the number of conductive elements 3 connected to the circuit.

[0017] Its further technical solution includes that determining the number of conductive elements 3 connected to the circuit based on the current value and the well condition parameters includes:

[0018] Determine the resistivity of the conductive element 3, the cable assembly 4 and the petroleum under different well condition parameters; determine the total resistance value in the circuit according to the power supply voltage value and the current value of the cable main line 401; calculate the number of conductive elements 3 connected to the circuit based on the resistivity of the conductive element 3, the cable assembly 4 and the petroleum and the total resistance value.

[0019] Its further technical solution includes that determining the number of conductive elements 3 connected to the circuit based on the current value and the well condition parameters includes:

[0020] Through a controlled variable experiment, with the well condition parameters and the number of conductive elements 3 connected to the circuit as independent variables and the current value of the cable main line 401 as the dependent variable, determine the corresponding relationship between the current value of the cable main line 401 and the number of conductive elements 3 connected to the circuit under different well condition parameters;

[0021] Based on the current value and the well condition parameters, determine the number of conductive elements 3 connected to the circuit in combination with the corresponding relationship.

[0022] Its further technical solution includes that the control variable test further includes, for any well condition parameter:

[0023] Select several key values of the well condition parameter, determine the current values corresponding to the several key values, and obtain the curve relationship between the well condition parameter and the current value through fitting.

[0024] Its further technical solution includes that the well condition parameter includes at least one of petroleum viscosity, petroleum water cut, petroleum temperature, and bottom hole pressure.

[0025] The beneficial effects of this application are as follows: The oil well flowing fluid level detection system and method designed in this application arrange several conductive elements and cable assemblies between the tubing and the casing, and are provided with a power supply and a current detection device on the wellhead. Utilizing the conductivity of petroleum, adjacent two conductive elements are electrically connected through petroleum to form a circuit loop; the depth of the flowing fluid level affects the number of conductive elements connected to the circuit, changes the total resistance in the circuit, and by detecting the circuit current, the corresponding depth of the flowing fluid level can be obtained, realizing the detection of the oil well flowing fluid level.

[0026] The oil well flowing fluid level detection method of this application also takes into account the influence of well condition parameters on the detection result, and accurate detection results can be obtained under various well depths, petroleum viscosities, and petroleum temperatures.

[0027] The conductive elements and cable assemblies of this application are evenly arranged on the tubing and can be lowered to the bottom of the well together with the tubing during well installation. They are not only position controllable, but also simple to assemble, without changing the original structure in the oil well, greatly saving material costs and labor costs, and can be installed in various types of oil wells, with a very wide range of applications.

[0028] The conductive elements and cable assemblies of this application can both withstand high temperatures, so they can also be applied in thermal recovery wells. And because the solution of this application utilizes the conductivity of the material, the higher the temperature, the better the conductivity, and it will not fail at high temperatures like the sensors used in the prior art.

[0029] This application detects the oil well flowing fluid level by monitoring the current value. Due to the inherent characteristics of the circuit, the information transmission speed is extremely fast, so the change of the flowing fluid level can be known in real time. The power supply can be set to be always on, or can be turned on when the flowing fluid level data is desired, with great flexibility.

[0030] The oil well flowing fluid level detection method of this application can not only be used in vertical wells, but also in deviated wells, horizontal wells, and irregular wells with a large dogleg severity, with a large tolerance for the wellbore structure, greatly improving the scope of application. Description of the Drawings

[0031] Figure 1It is a schematic structural diagram of the first connection method between a cable assembly and a conductive element in an embodiment of the present application.

[0032] Figure 2 It is a circuit diagram corresponding to the first connection method between a cable assembly and a conductive element in an embodiment of the present application.

[0033] Figure 3 It is a schematic structural diagram of the second connection method between a cable assembly and a conductive element in an embodiment of the present application.

[0034] Figure 4 It is a circuit diagram corresponding to the second connection method between a cable assembly and a conductive element in an embodiment of the present application.

[0035] Figure 5 It is an equivalent circuit diagram corresponding to the first connection method between a cable assembly and a conductive element in an example of the present application.

[0036] Figure 6 It is an equivalent circuit diagram corresponding to the second connection method between a cable assembly and a conductive element in an example of the present application.

[0037] Reference numerals: 1, tubing; 2, casing; 3, conductive element; 4, cable assembly; 401, main cable; 402, cable branch; 5, insulating box. Detailed implementation manners

[0038] The following will describe the detailed implementation manners of the present application with reference to the accompanying drawings.

[0039] The dynamic liquid level of an oil well refers to the depth of the liquid column top interface between the tubing and the casing. During oil production, it is affected by various factors, such as formation liquid supply capacity, pumping intensity, gas-oil ratio, wellbore integrity, reservoir pressure, etc. This makes the dynamic liquid level show irregular changes in actual oil production and is difficult to predict through simple model analysis.

[0040] In addition, due to the certain viscosity of petroleum itself, in order to enable petroleum to smoothly lift through hundreds or thousands of meters of tubing to the ground, thermal recovery oil production is usually used, that is, before oil production, high-temperature steam is first injected into the well to reduce the viscosity of petroleum. This means that the downhole environment will maintain a relatively high temperature for a long time, up to 360 degrees Celsius at the highest, which further increases the difficulty of dynamic liquid level measurement.

[0041] To solve this problem, the present application proposes an oil well dynamic liquid level detection system. In this embodiment, as Figure 1As shown in the figure, the moving liquid level detection system for oil wells includes a tubing 1 and a casing 2 that are conventionally arranged in the oil well. The moving liquid level is located between the tubing 1 and the casing 2. The main inventive point of this application is that the system further includes a plurality of conductive elements 3, a cable assembly 4, a power supply, and a current detection device. The conductive elements 3 are distributed along the axial direction of the tubing 1 and are located at a fixed height between the tubing 1 and the casing 2. The cable assembly 4 includes two separated main cable lines 401. The upper ends of the two main cable lines 401 are respectively connected to the positive and negative poles of the power supply, and the lower ends of the two main cable lines 401 are connected to the conductive elements 3 through a plurality of cable branches 402. Each conductive element 3 is only connected to one cable branch 402. The current detection device is used to detect the current value of the main cable line 401.

[0042] In an actual oil well, oil production equipment (such as a progressing cavity pump) is arranged inside the tubing 1, and the extracted oil is transported to the ground inside the tubing 1. The casing 2 is fixed to the inner wall of the wellbore and has a certain gap with the tubing 1.

[0043] Among them, the cable assembly 4 is laid from the ground along the tubing 1 to a depth of hundreds of meters underground. It can be laid along the outer wall of the tubing 1 or arranged inside the tubing 1, and then connected to the external conductive elements 3 at each cable branch 402. Figure 1 The figure shown is only a schematic diagram of a partial section underground. Among them, the tubing 1, the casing 2, and the cable assembly 4 will continuously extend upward to the ground, and the power supply and the current detection device are both arranged on the ground.

[0044] In this embodiment, the cable assembly 4 includes a conductive core and an insulating layer wrapped around the conductive core, and the temperature tolerance of the conductive core and the insulating layer is greater than the highest temperature of the thermal recovery well. The conductive core is only in electrical contact with the conductive element 3 underground and is insulated from both the oil and the tubing 1.

[0045] Optionally, the material of the conductive core is graphite or cermet, which has strong conductivity and high temperature resistance.

[0046] Optionally, the insulating layer is a double-layer encapsulation structure, with an inner layer of alumina ceramic and an outer layer of polytetrafluoroethylene, with a temperature resistance of up to 400°C and resistance to hydrogen sulfide corrosion.

[0047] Optionally, the conductive element 3 uses a zirconium boride-silicon carbide ceramic electrode, which can withstand a high temperature of 360°C and is corrosion-resistant, ensuring a service life of more than 5 years.

[0048] There are several connection methods between the cable assembly 4 and the conductive element 3. Due to space limitations, only two relatively optimal connection methods are elaborated in this embodiment:

[0049] (1) Two adjacent conductive elements 3 in the axial direction are connected to the cable branches 402 corresponding to different main cable lines 401.

[0050] Such as Figure 1As shown, the cable branches 402 of the main cable 401 distributed on both sides of the conductive element 3 are alternately connected to the conductive element 3, and the corresponding circuit diagram is as Figure 2 shown. When the moving liquid level submerges a certain conductive element 3, all the conductive elements between this conductive element 3 and those below it are connected pairwise to form a path.

[0051] (2) One main cable 401 is connected to the lowermost conductive element 3, and the other main cable 401 is connected to the remaining conductive elements 3 through a plurality of cable branches 402.

[0052] As Figure 3 shown, the circuit diagram corresponding to the connection mode of the conductive element 3 and the cable branch 402 in this figure is Figure 4 , when the moving liquid level submerges a certain conductive element 3, this conductive element 3 and all the conductive elements below it form a path with the lowermost conductive element 3.

[0053] In this embodiment, the oil well moving liquid level detection system further includes a protection resistor. The protection resistor is connected in series on one of the main cables 401 and is connected in parallel with a voltmeter. The main function of the protection resistor is to prevent excessive current in the circuit from damaging the system. After being connected in parallel with the protection resistor, the voltmeter is equivalent to a current detection device, and the current of the main cable 401 can be calculated by combining the voltage V0 of the protection resistor and the resistance value R0 of the protection resistor. If a voltmeter is not used, an ammeter can also be directly connected in series on the main cable 401 as a current detection device.

[0054] In this embodiment, the conductive element 3 is arranged in a semi - open insulating box 5 and is fixed at a fixed height of the oil pipe 1 through the insulating box 5; the distance between the insulating box 5 and the casing 2 is less than the distance between the conductive element 3 and the casing 2.

[0055] Optionally, the open side of the insulating box 5 faces the casing 2, so that the conductive element 3 inside it can better contact with the oil. In addition, the height of the insulating box 5 is greater than the height of the conductive element 3. On the one hand, it can avoid the vibration of the oil pipe 1 during oil production, which may cause friction between the conductive element 3 and the casing 2, thereby changing the resistance value of the conductive element 3. On the other hand, it can avoid the electrical contact between the conductive element 3 and the casing 2, thereby changing the resistance value in the circuit and causing the current value to be disordered.

[0056] Another embodiment of the present application also discloses an oil well moving liquid level detection method, including:

[0057] Obtaining the current value of the main cable 401 and the well condition parameters of the oil well, determining the number of conductive elements 3 connected to the circuit based on the current value and the well condition parameters, and determining the depth of the moving liquid level according to the number of conductive elements 3 connected to the circuit.

[0058] The main principle of this method is to utilize the electrical conductivity of petroleum: the electrical conductivity of petroleum is mainly affected by factors such as the composition, temperature, and pressure of petroleum. Generally speaking, the resistivity of petroleum decreases as the water content in petroleum increases, and other metal ions in petroleum will also affect the resistivity of petroleum. An increase in temperature or pressure will also cause the resistivity of petroleum to decrease. Therefore, the unexploited petroleum underground that contains various impurities is electrically conductive.

[0059] When the petroleum between the tubing 1 and the casing 2 submerges multiple conductive elements 3, a current will be generated between the conductive elements 3. At this time, the petroleum is equivalent to a wire, making the entire circuit form a closed path. The change in the depth of the fluid level will affect the number of submerged conductive elements 3, thereby changing the resistance value in the circuit. When the power supply voltage remains unchanged, the change in the resistance value will cause the current value to change correspondingly. Therefore, the depth of the fluid level can be determined by detecting the current value.

[0060] Optionally, the current value of the main cable 401 is obtained through a current detection device, and the well conditions parameters of the oil well are obtained through various sensors.

[0061] In one embodiment, determining the number of conductive elements 3 connected to the circuit based on the current value and the well conditions parameters includes:

[0062] Determining the resistivity of the conductive elements 3, the cable assembly 4, and the petroleum under different well conditions parameters; determining the total resistance value in the circuit according to the power supply voltage value and the current value of the main cable 401; calculating the number of conductive elements 3 connected to the circuit based on the resistivity of the conductive elements 3, the cable assembly 4, and the petroleum and the total resistance value.

[0063] Specifically, the resistivity of the conductive elements 3 and the cable assembly 4 is mainly affected by temperature, and their materials and dimensional specifications have been determined during installation. Therefore, the relationship between their resistance value and resistivity can be directly calculated through the formula R = ρL / S, where R is the resistance value, ρ is the resistivity of the material used to make the resistor, L is the length of the resistor, and S is the cross-sectional area of the resistor.

[0064] However, it is more difficult to calculate the relationship between the resistivity of petroleum and its resistance through a theoretical formula because in the specific scenario of this embodiment, the petroleum covers the entire annulus between the tubing 1 and the casing 2, but its contact surface with the conductive elements 3 is only a small part. Therefore, it cannot be calculated through the conventional resistance formula; in addition, there are many factors affecting the resistivity of petroleum, and the change in resistivity is more complex and difficult to calculate directly.

[0065] Therefore, in one embodiment, a conductive element 3 and a cable assembly 4 with a larger resistivity are selected so that the resistance value of the conductive element 3 and the cable assembly 4 connected to the circuit is much greater than the resistance value of the oil. In another embodiment, the distance between two adjacent conductive elements 3 is set to be less than or equal to the set distance, so that the oil resistance value accounts for a smaller proportion of the entire circuit resistance value; illustratively, the set distance is 1 meter. In some oil wells with a higher water content, the conductivity of oil is stronger, and the distance between two adjacent conductive elements 3 can be set to a maximum of 10 meters. In both cases, only the parameters that have the greatest impact on the resistivity of oil can be considered as well condition parameters to obtain the resistivity of oil under different parameters under different well conditions. For example, only the effects of temperature and viscosity on the resistivity of oil are considered, and then the theoretical resistance of oil is calculated according to the conventional resistance formula.

[0066] In addition, through finite element simulation, various well parameters, the distance between the conductive elements 3, the cross-sectional area of the annulus between the oil pipe 1 and the casing 2, etc. can be used as input quantities to fit the resistivity and / or resistance value of the oil.

[0067] Since two connection methods between the conductive element 3 and the cable assembly 4 are disclosed in the present application, in order to illustrate the calculation of the resistance value in the circuit at different dynamic liquid level depths, an example is described below.

[0068] Assume that the dynamic liquid surface is located between R4 and R5, that is, there are 4 conductive elements connected to the circuit. For the convenience of calculation, assume that the resistance value of each conductive element 3 is r.

[0069] (1) When two axially adjacent conductive elements 3 are connected to cable branches 402 corresponding to different cable main lines 401, as shown in FIG. Figure 2 , 5 As shown in the equivalent circuit diagram, since the resistance values of each resistor are equal, the actual equivalent is R2 and R4 in parallel, R1 and R3 in parallel, and the two sets of parallel resistors are connected in series. The total resistance of the conductive element 3 connected to the circuit is , where r is the resistance value of a single conductive element 3.

[0070] (2) When a main cable line 401 is connected to the bottom conductive element 3, and another main cable line 401 is connected to the remaining conductive elements 3 through a plurality of cable branches 402, as shown in FIG. Figure 4 , 6 As shown in the equivalent circuit diagram, since the resistance values of each resistor are equal, it is actually equivalent to R2, R3, and R4 connected in series and then connected in parallel with R1. The total resistance value of the conductive element 3 connected to the circuit is .

[0071] The above method only calculates the resistance value of the conductive element 3. In actual implementation, since the depth of the oil well is hundreds or thousands of meters, and the cable assembly is also long, when calculating the total resistance in the circuit, in order to improve the detection accuracy, the resistance of the cable assembly should also be taken into account. When the material, temperature, length, and cross-section of the cable assembly are known, its resistance value can be calculated.

[0072] In another embodiment, determining the number of conductive elements 3 connected to the circuit based on the current value and the well condition parameter includes:

[0073] Through the control variable test, with the well condition parameters and the number of conductive elements 3 connected to the circuit as independent variables and the current value of the cable main line 401 as the dependent variable, the corresponding relationship between the current value of the cable main line 401 and the number of conductive elements 3 connected to the circuit under different well condition parameters is determined; based on the current value and the well condition parameters, the number of conductive elements 3 connected to the circuit is determined in combination with the corresponding relationship.

[0074] This method does not need to calculate resistivity. The advantage is that it eliminates the intermediate quantity and the result is more accurate. The disadvantage is that a large amount of test data is required in the early control variable test to cover various possible well parameters. Therefore, in actual use, the control variable test also includes, for any well parameter: selecting several key values of the well parameter, determining the current values corresponding to several key values, and obtaining the curve relationship between the well parameter and the current value by fitting.

[0075] For example, the selected oil temperatures are 60℃, 90℃, 120℃, 150℃, 180℃, 210℃, 240℃, 270℃, 300℃, 330℃, and 360℃. By fitting the curve relationship between oil temperature and current value, the current value corresponding to any oil temperature can be obtained, and the same is true for other well parameters.

[0076] Optionally, the well condition parameters include at least one of oil viscosity, oil water content, oil temperature, and bottom hole pressure.

[0077] In this embodiment, determining the dynamic liquid level depth according to the number of conductive elements 3 connected to the circuit includes:

[0078] Since the conductive elements 3 are arranged along the axial direction of the oil pipe 1, the dynamic liquid level also fluctuates between the oil pipe 1 and the casing 2 and along the axial direction of the oil pipe 1. Therefore, when the number of conductive elements 3 connected to the circuit is known, the corresponding dynamic liquid level depth can be inferred. For example, in an oil well with a depth of 1,000 meters, a number of conductive elements 3 are evenly arranged on the oil pipe 1 with a depth of 500-800 meters. If no conductive element 3 is connected to the circuit, it means that the depth of the dynamic liquid level is greater than or equal to 800 meters. If half of the conductive elements 3 are connected to the circuit, the depth of the dynamic liquid level is about 650 meters.

[0079] The fluid level detection method of this application can be used not only in vertical wells, but also in deviated wells and horizontal wells. Before installing the tubing, various trajectory parameters of the oil well are known, and the positions of the conductive elements 3 on the tubing are also known. According to parameters such as the well deviation angle and well depth, the fluid level depth corresponding to each conductive element 3 can be calculated. For example, if a certain conductive element 3 is installed on the nth section of tubing counted from the wellhead downwards, and the length of each section of tubing is L, according to the trajectory parameters of the oil well, the well depth corresponding to the oil well trajectory length of nL can be known, so as to obtain the fluid level depth corresponding to this conductive element 3.

[0080] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0081] The above description is an explanation of the present invention, not a limitation of the invention. The scope defined by the present invention can be seen in the claims. Within the protection scope of the present invention, any form of modification can be made.

Claims

1. An oil well flowing fluid level detection system, comprising a tubing string (1) and a casing (2), with the flowing fluid level located between the tubing string (1) and the casing (2), characterized in that, The dynamic liquid level detection system of the oil well further includes a plurality of conductive elements (3), a cable assembly (4), a power supply, and a current detection device; The conductive elements (3) are distributed along the axial direction of the oil pipe (1) and are located at a fixed height between the oil pipe (1) and the casing (2); The cable assembly (4) includes two separated main cable lines (401). The upper ends of the two main cable lines (401) are respectively connected to the positive and negative poles of the power supply. The lower ends of the two main cable lines (401) are connected to the conductive elements (3) through a plurality of cable branches (402). Each conductive element (3) is only connected to one cable branch (402); the current detection device is used to detect the current value of the main cable line (401).

2. The oil well flowing fluid level detection system according to claim 1, characterized in that, The connection mode of the cable assembly (4) and the conductive element (3) includes: two adjacent conductive elements (3) in the axial direction are connected to the cable branches (402) corresponding to different main cable lines (401).

3. The oil well flowing fluid level detection system according to claim 1, wherein The connection mode of the cable assembly (4) and the conductive element (3) includes: one main cable line (401) is connected to the lowermost conductive element (3), and the other main cable line (401) is connected to the remaining conductive elements (3) through a plurality of cable branches (402).

4. The oil well flowing fluid level detection system according to claim 1, characterized in that The dynamic liquid level detection system of the oil well further includes a protection resistor. The protection resistor is connected in series to one of the main cable lines (401) and is connected in parallel with a voltmeter.

5. The oil well flowing fluid level detection system according to claim 1, wherein The conductive element (3) is arranged in a semi-open insulation box (5) and is fixed at a fixed height of the oil pipe (1) through the insulation box (5); the distance between the insulation box (5) and the casing (2) is less than the distance between the conductive element (3) and the casing (2).

6. A method for detecting the dynamic liquid level of an oil well, which is applied to the oil well dynamic liquid level detection system described in any one of claims 1-5, and is characterized in that, The dynamic liquid level detection method of the oil well includes: Obtaining the current value of the main cable line (401) and the well condition parameters of the oil well, determining the number of conductive elements (3) connected to the circuit based on the current value and the well condition parameters, and determining the dynamic liquid level depth according to the number of conductive elements (3) connected to the circuit.

7. The method for detecting the dynamic liquid level of an oil well according to claim 6, wherein, The determining the number of conductive elements (3) connected to the circuit based on the current value and the well condition parameters includes: Determining the resistivity of the conductive element (3), the cable assembly (4), and the petroleum under different well condition parameters; determining the total resistance value in the circuit according to the power supply voltage value and the current value of the main cable line (401); calculating the number of conductive elements (3) connected to the circuit based on the resistivity of the conductive element (3), the cable assembly (4), and the petroleum and the total resistance value.

8. The oil well flowing fluid level detection method according to claim 6, characterized in that, The determining the number of conductive elements (3) connected to the circuit based on the current value and the well condition parameters includes: Through a controlled variable experiment, taking the well condition parameters and the number of conductive elements (3) connected to the circuit as independent variables and the current value of the main cable line (401) as the dependent variable, determining the corresponding relationship between the current value of the main cable line (401) and the number of conductive elements (3) connected to the circuit under different well condition parameters; Based on the current value and the well condition parameters, determining the number of conductive elements (3) connected to the circuit in combination with the corresponding relationship.

9. The method for detecting the dynamic liquid level of an oil well according to claim 8, characterized in that, The controlled variable experiment further includes, for any well condition parameter: Select several key values of the well condition parameters, determine the current values corresponding to the several key values, and obtain the curve relationship between the well condition parameters and the current values by fitting.

10. The oil well flowing fluid level detection method according to claim 6, characterized in that, The well condition parameters include at least one of petroleum viscosity, petroleum water cut, petroleum temperature, and bottom hole pressure.

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