Method for detecting flow velocity of fluid outside pipe by using electromagnetic heating method

Abstract

The method comprises the following steps: locally heating the inner wall of an oil pipe by using an electromagnetic coil, and recording the temperature change of the inner wall of the oil pipe through a temperature probe at the position where the center of the electromagnetic coil clings to the wall of the oil pipe; the oil pipe casing pipe is filled with water, when the water in the oil sleeve annulus flows at different flows, the relation between the flow and the temperature change of the inner wall of the oil pipe is obtained, and instrument calibration is completed; measuring points are carefully selected, the oil pipe is heated, and the corresponding flow outside the pipe is obtained according to the obtained instrument scales. By measuring the flow velocity outside the oil pipe, personnel can be prevented from radiation injury during well logging, a method for measuring the flow velocity outside the pipe by using an isotope radioactivity method is completely eliminated, the well logging precision is improved, and the quality is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil logging, and relates to a method for detecting the flow rate of fluid outside the pipe using electromagnetic heating method. Background Art

[0002] In production logging, in addition to measuring the fluid inside the tubing or casing, water injection profile logging often needs to measure the water flow velocity between the tubing and the casing annulus in order to obtain the flow rate of each perforation layer and measure the annulus flow rate (velocity). Currently, the solid isotope method, the liquid isotope correlation flow method, and oxygen activation logging are commonly used to measure the water flow velocity outside the casing. These measurement methods have the following deficiencies:

[0003] ① All of them need to use radioactive substances or radioactive devices, posing risks of radiation injury to operators and environmental protection.

[0004] ② The solid isotope method needs to use unsealed radioactive substances, and the commonly used ones are microsphere powder carriers, iodine - 131, and barium - 131. There is also the problem that due to the unclean wellbore, solid isotope particles adhere to the wellbore, resulting in inconsistent calculation results with the actual water absorption, that is, a large error. At the same time, the specific value of the error cannot be estimated, making the interpretation coincidence rate low.

[0005] ③ For the liquid isotope correlation flow method, it is necessary to repeatedly lower and raise the instrument to calculate the corresponding depth difference and time difference between adjacent gamma peaks to calculate the flow velocity. Due to the limitation of the peak number for velocity measurement, the layer positions cannot be subdivided in detail, and it is difficult to determine the tracer diffusion peak in the case of low flow velocity.

[0006] ④ Oxygen activation method: The half - life of oxygen - activated nitrogen is 7.13 seconds. When the flow velocity is low, the activated substance decays before reaching the detector, and the low - speed flow cannot be measured.

[0007] In summary, the existing methods for measuring the flow velocity of the tubing - casing annulus have problems such as radiation injury, environmental protection issues, and insufficient measurement accuracy. Summary of the Invention

[0008] The purpose of the present invention is to solve the problems in the prior art, and provide a method for detecting the flow rate of fluid outside the pipe using electromagnetic heating method, so as to solve the problems of radiation injury, environmental protection issues, and insufficient measurement accuracy existing in the prior art.

[0009] To achieve the above - mentioned purpose, the present invention adopts the following technical solutions:

[0010] A method for detecting the flow rate of fluid outside the pipe using electromagnetic heating method, including:

[0011] Locally heating the inner wall of the tubing using an electromagnetic coil, and recording the temperature change of the inner wall of the tubing through a temperature probe at a position where the center of the electromagnetic coil is closely attached to the tubing wall;

[0012] The inside of the tubing-casing pipe is filled with water. When the water in the tubing-casing annulus flows at different flow rates, the relationship between the flow rate and the temperature change of the inner wall of the tubing is obtained.

[0013] Select measurement points, heat the tubing, and obtain the corresponding flow rate outside the pipe based on the relationship between the flow rate and the temperature change of the inner wall of the tubing.

[0014] Furthermore, a rubber seal is provided at the contact position between the electromagnetic coil and the inner wall.

[0015] Furthermore, the temperature probe is pressed against the tubing wall tightly.

[0016] Furthermore, the temperature probe is wrapped with heat-insulating material and completely separated from the water flow inside the pipe.

[0017] Furthermore, the electromagnetic coil uses a three-core cable. Each core realizes one function. The heating and pushing functions are realized by negative electricity. Different negative voltages are used for heating and pushing respectively, and positive voltage is used for measurement.

[0018] Furthermore, the relationship between the flow rate and the temperature change of the inner wall of the tubing is the relationship between the equilibrium point temperature difference and the flow velocity outside the pipe.

[0019] Furthermore, the process of establishing the relationship between the equilibrium point temperature difference and the flow velocity outside the pipe is as follows:

[0020] S1: Adjust the water flow velocity v to be stable;

[0021] S2: Heat the tubing to obtain the temperature difference between the initial temperature and the equilibrium point temperature, which is the equilibrium point temperature difference ΔT;

[0022] S3: Use multiple water flow velocities, execute S1 to S2, and form a two-dimensional relationship of v-ΔT.

[0023] Furthermore, the relationship between the flow rate and the temperature change of the inner wall of the tubing is the relationship between the time required to heat up to the same temperature and the flow velocity outside the pipe.

[0024] Furthermore, the process of establishing the relationship between the time required to heat up to the same temperature and the flow velocity outside the pipe is as follows:

[0025] S1: Adjust the water flow velocity v to be stable and record the initial tubing wall temperature;

[0026] S2: Heat the tubing and record the tubing wall temperature simultaneously until the temperature no longer rises;

[0027] S3: Obtain the equilibrium point temperature difference ΔT by heating at the maximum flow rate max , and then heat the tubing wall to a temperature slightly lower than ΔT1 under other flow conditions, and process the data to obtain the time Δt used from when the electromagnetic coil is powered on to when the temperature reaches ΔT1 each timen , relate Δt n and the flow velocity V n to establish a relationship. By taking the derivative of the temperature change curve with respect to time under different flow rate conditions, an extreme value of the temperature increase rate DT can be obtained max , and obtain DT max -V n relationship;

[0028] S4: Taking the starting time of the first inflection point of the derivative, obtain the relationship curve between the temperature rise difference of the water temperature and the required time under the condition that the water flow velocity v is constant;

[0029] S5: Loop and execute the above S1 to S4 to obtain the relationship curve between the temperature rise difference of the water temperature and the required time at multiple water flow velocities when the electromagnetic power is P;

[0030] S6: Change the electromagnetic power to P1, loop and execute the above S1 to S5 to obtain the relationship curve between the temperature rise difference of the water temperature and the required time at multiple water flow velocities when the electromagnetic power is P1, and form the relationship among the electromagnetic power, the water flow velocity outside the pipe, the temperature rise difference of the water temperature and the required time.

[0031] Furthermore, the relationship between the flow rate and the temperature change of the inner wall of the oil pipe is the relationship between the heating temperature rise speed limit value and the flow velocity outside the pipe.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a method for detecting the flow velocity of the fluid outside the pipe using the electromagnetic heating method. The electromagnetic heating method is used to locally heat the oil pipe, thereby establishing the relationship between the flow velocity outside the pipe and the balance point temperature difference, establishing the relationship between the flow velocity outside the pipe and the time required to rise the same temperature, and establishing the relationship between the flow velocity of the fluid outside the pipe and the extreme value of the heating rate. The method of detecting the flow velocity of the fluid outside the pipe by heating the inner wall of the oil pipe and simultaneously recording the temperature of the oil pipe wall can be used as the theoretical basis for the manufacture of a flowmeter. Measuring the flow velocity outside the oil pipe by the present invention can protect the personnel from radiation damage during well logging, completely get rid of the method of using the isotope radioactive method to measure the flow rate outside the pipe, improve the well logging accuracy and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a schematic diagram for implementing the method for detecting the flow velocity of the fluid outside the pipe using the electromagnetic heating method of the present invention.

[0036] Figure 2 This is a schematic diagram of the verification test device for the present invention.

[0037] Among them: 1 - casing wall, 2 - tubing wall, 3 - annular flow of water between tubing and casing, 4 - push plate, 5 - heating coil, 6 - temperature probe, 11 - water tank, 12 - water pump, 13 - simulated tubing, 14 - flowmeter, 15 - induction cooker, 16 - direct-reading temperature measuring instrument, 17 - temperature measuring probe. Specific embodiments

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0040] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0041] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the present invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0042] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0043] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if the terms "set", "install", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] The following further describes the present invention in detail with reference to the accompanying drawings:

[0045] See Figure 1 , the present invention provides a method for detecting the flow rate of fluid outside the pipe using electromagnetic heating, including the following steps:

[0046] Locally heat the oil pipe wall 2 with an electromagnetic coil, set a temperature probe 6 closely against the center of the coil to record the temperature change of the oil pipe wall 2, and seal the contact position between the heating coil 5 and the oil pipe wall 2 with a rubber ring to ensure that the contact position is not affected by the surrounding fluid;

[0047] Fill the inside of the oil pipe casing with water. When the water in the annulus of the oil pipe casing flows at different flow rates (velocities), the relationship between the flow rate and the temperature change can be obtained to complete the calibration of the instrument;

[0048] When in use, select the measurement points (depths) carefully, heat the oil pipe, record the temperature change, and obtain the corresponding flow rate outside the pipe by looking up a table or calculating based on the obtained temperature change.

[0049] In order to measure the temperature of the oil pipe wall 2, the temperature probe 6 must be in reliable contact with the oil pipe wall 2. Add a push plate 4 and press the temperature probe 6 tightly against the oil pipe wall 2 when measuring the temperature.

[0050] In order to make the temperature probe 6 not affected by the flow rate inside the pipe and maximize the influence of the temperature probe 6 on the fluid outside the pipe, wrap the temperature probe with heat insulation material to completely separate it from the water flow inside the pipe.

[0051] In order to achieve the three functions of measurement, heating, and pushing, and make the three functions independent of each other, use a three-core cable, and each use a cable core to achieve one function. The heating and pushing functions are realized using negative electricity; different negative voltages are used for heating and pushing respectively; the measurement is realized using positive voltage.

[0052] Embodiment 1:

[0053] A method for detecting the flow rate of fluid outside the pipe using electromagnetic heating, including the following steps:

[0054] Locally heat the oil pipe wall 2 with an electromagnetic coil. A temperature probe 6 is arranged closely to the center of the coil against the oil pipe wall 2 to record the temperature change of the oil pipe wall 2. The contact position between the heating coil 5 and the oil pipe wall 2 is sealed by a rubber ring to ensure that the contact position is not affected by the surrounding fluid.

[0055] Fill the inside of the oil pipe casing with water. When the water in the annulus between the oil pipe and the casing flows at different flow rates (velocities), the relationship between the flow rate and the temperature change can be obtained, the instrument calibration can be completed, and the relationship between the equilibrium point temperature difference and the external pipe flow velocity can be established. With a certain electromagnetic power, use the following steps:

[0056] A1: Adjust the water flow velocity v to be stable and record v.

[0057] A2: Heat the oil pipe to obtain the equilibrium point temperature difference ΔT (the temperature difference between the initial temperature and the equilibrium point temperature).

[0058] A3: Use multiple water flow velocities and execute A1 - A2 to form a two-dimensional relationship table of v - ΔT.

[0059] Use the equilibrium point temperature difference to measure the external pipe flow velocity. With a certain electromagnetic power, use the following steps:

[0060] B1: Heat the oil pipe to obtain the equilibrium point temperature difference ΔT (the temperature difference between the initial temperature and the equilibrium point temperature).

[0061] B2: Check the two-dimensional relationship table of v - ΔT and obtain the water flow velocity v from ΔT.

[0062] B3: Calculate the external pipe water flow rate using the water flow velocity v.

[0063] Embodiment 2:

[0064] A method for detecting the external pipe fluid flow velocity using electromagnetic heating includes the following steps:

[0065] Locally heat the oil pipe wall 2 with an electromagnetic coil. A temperature probe 6 is arranged closely to the center of the coil against the oil pipe wall 2 to record the temperature change of the oil pipe wall 2. The contact position between the heating coil 5 and the oil pipe wall 2 is sealed by a rubber ring to ensure that the contact position is not affected by the surrounding fluid.

[0066] Fill the inside of the oil pipe casing with water. When the water in the annulus between the oil pipe and the casing flows at different flow rates (velocities), the relationship between the flow rate and the temperature change can be obtained, the instrument calibration can be completed, and the relationship diagram between the time required to heat up the same temperature and the external pipe flow velocity can be established. With a certain electromagnetic power P, use the following steps:

[0067] C1: Adjust the water flow velocity v to be stable, record v, and record the initial pipe wall temperature (water temperature).

[0068] C2: Heat the oil pipe and record the pipe wall temperature simultaneously until the temperature no longer rises, then turn off the electromagnetic heating.

[0069] C3: Play back the recorded temperature data. Since it is known that the highest flow rate corresponds to the lowest temperature equilibrium point, at the beginning of the scale, first heat at the highest flow rate to obtain the equilibrium point temperature difference ΔT. max Then, heat the oil pipe wall to a temperature slightly lower than ΔT max by ΔT max -0.5 degrees under other flow rate conditions, which can save heating time and reduce the coil load. The data processing obtains the time Δt max used from heating by the electromagnetic coil to the temperature reaching ΔT n -0.5 degrees each time. Establish a relationship chart of Δt n and the flow rate V n . Differentiate the temperature change curve with respect to time under each flow rate condition to obtain an extreme value DT max of the temperature increase rate. Experiments find that this value generally appears in the later stage of the rapid heating stage and is related to the fluid participating in heat dissipation. Obtain the DT max -V n relationship chart.

[0070] C4: Take the starting time when the first inflection point appears in the derivative, and obtain the relationship curve between the temperature rise difference of the water temperature and the required time under the condition that the water flow velocity v is constant.

[0071] C5: Loop and execute the above steps C1 - C4 to obtain the relationship curve between the temperature rise difference of the water temperature and the required time at multiple water flow velocities when the electromagnetic power is P.

[0072] C6: Change the electromagnetic power to P1, loop and execute the above steps C1 - C5 to obtain the relationship curve between the temperature rise difference of the water temperature and the required time at multiple water flow velocities when the electromagnetic power is P1, and form a relationship chart of electromagnetic power, water flow velocity outside the pipe, temperature rise difference of the water temperature, and required time.

[0073] Use the time chart required to heat up to the same temperature to measure the water flow velocity outside the pipe. Keep the electromagnetic power stable and execute the following steps:

[0074] D1: Heat the oil pipe wall and record the wall temperature with a direct-reading temperature measuring instrument.

[0075] D2: Differentiate the wall temperature-time curve.

[0076] D3: Determine the starting time T0 for calculation from the derivative curve obtained in step D2.

[0077] D4: Correlate T0 to the wall temperature-time curve.

[0078] D5: Obtain the relationship curve between the wall temperature rise and the time starting from T0.

[0079] D6: Using the curve obtained from D5, create a graph showing the relationship between electromagnetic power, the water flow velocity outside the pipe, the temperature rise difference of the water, and the required time, and obtain the water flow velocity outside the pipe.

[0080] Example 3:

[0081] A method for detecting the fluid flow velocity outside a pipe using electromagnetic heating includes the following steps:

[0082] Locally heat the oil pipe wall 2 using an electromagnetic coil. Place a temperature probe 6 closely against the oil pipe wall 2 at the center of the coil to record the temperature change of the oil pipe wall 2. The contact position between the heating coil 5 and the oil pipe wall 2 is sealed by a rubber ring to ensure that the contact position is not affected by the surrounding fluid.

[0083] Fill the inside of the oil pipe casing with water. When the water in the annulus between the oil pipe and the casing flows at different flow rates (velocities), the relationship between the flow rate and the temperature change can be obtained, the instrument calibration can be completed, the relationship graph between the heating and temperature rise speed limit value and the flow velocity outside the pipe can be established, and the flow velocity outside the pipe can be measured using the heating and temperature rise speed limit value graph.

[0084] To verify the above scheme, the present invention designs and uses an experimental device to verify the above scheme. As Figure 2 shown, the test device includes a water tank 11, a water pump 12, a simulated oil pipe 13, a flow meter 14, an induction cooker 15, a direct-reading temperature measuring instrument 16, and a temperature measuring probe 17.

[0085] One end of the water tank 11 is connected to the simulated oil pipe 13 through a pipeline. A water pump 12 is provided on the pipeline between the water tank 11 and the simulated oil pipe 13. The water tank 11 is used to store water to provide a stable water source for this equipment. The simulated oil pipe 13 is used to simulate the oil pipe to be heated underground. The water pump 12 is used to pump water from the upper part of the water tank 11 and pump it into the simulated oil pipe 13. This water pump 12 has at least 3 gears to form at least 3 different flow rates under the condition that other conditions remain unchanged, which is convenient for comparing the influence of the flow rate on the system.

[0086] A flow meter 14 is installed on the pipeline at the other end of the simulated oil pipe 13 to measure the current flow rate in the system. An induction cooker 15 is provided at the bottom of the simulated oil pipe 13, closely against the bottom of the simulated oil pipe 13, to heat the simulated oil pipe 13. The advantage of electromagnetic heating is that once the heating stops, the heating element has no influence on the object to be heated, that is, there is no residual temperature. The disadvantage of electric furnace heating is that there is still residual temperature once the heating stops. The temperature measuring probe 17 is closely against the outer wall of the simulated oil pipe 13, and the temperature measuring probe 17 is connected to the direct-reading temperature measuring instrument 16 to record the temperature change of the simulated oil pipe 13 wall over time.

[0087] Test conditions and methods: Let water with 3 different initial temperatures flow through the simulated oil pipe 13 at 3 different flow rates, record the initial temperature and flow rate, and heat the oil pipe wall using the same electromagnetic power.

[0088] Experimental findings: 1. There is a correlation between the heating temperature equilibrium point and the flow rate. When the temperature is constant and the heating power is constant, there is a limit during the temperature rise process. When this temperature is reached, heating and heat dissipation reach equilibrium. This equilibrium point temperature is related to the flow rate under the condition of constant input power. The greater the flow rate, the lower the equilibrium point temperature. Converting the three gears of the water pump into actual flow rates and equilibrium point temperatures has a good correlation. After calculation, the difference ΔT between the equilibrium point temperature and the initial temperature is constant when the flow rate is unchanged.

[0089] Theoretical description of the experimental conclusion:

[0090] Under the condition that the power P of electromagnetic heating is constant, the power p1 absorbed by the water heated per unit time is constant, that is

[0091] p1 = ηP (1)

[0092] In the formula, η is the conversion efficiency of the induction cooker.

[0093] Meanwhile

[0094] p1 = mcΔT (2)

[0095] In the formula, m is the mass of the water flowing near the pipe wall per unit time, c is the specific heat of water, which is a constant, and ΔT is the temperature rise of the water per unit time.

[0096] From the above formula, it can be obtained that under the condition that p1 is a fixed value, m is inversely proportional to ΔT.

[0097] From the definition of m, it can be known that

[0098] m = ρsv (3)

[0099] In the formula, ρ is the density of water, which is a constant, s is the cross-sectional area near the pipe wall, v is the water flow velocity, and the product of sv is the volume of water.

[0100] Substituting formula (3) into formula (2) gives: under the condition that p1 is a fixed value, v is inversely proportional to ΔT, which is the same as the experimental conclusion.

[0101] 2. The time required to heat up to the same temperature is correlated with the flow rate. There is a rapid heating and cooling process. When rising to the same temperature, the greater the flow rate, the longer the time required. Converting the flow rate gears into flow velocities, the three flow velocities and the time taken to reach the same temperature are correlated.

[0102] 3. The maximum temperature rise speed during the heating process is correlated with the flow velocity outside the pipe. Taking the derivative of the experimental heating curves of the three flow rates and static water with respect to time, the following law is found: It is found that the maximum value (the temperature rise value per unit time) in the rapid heating stage is correlated with the flow velocity, and the lower the flow velocity, the greater the extreme value.

[0103] Therefore, based on the above correlations, it shows that the method of using electromagnetic heating to locally record the temperature curve of the oil pipe in the present invention can detect the fluid flow rate outside the pipe, and this testing method is feasible.

[0104] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for detecting the flow rate of fluid outside a pipe using electromagnetic heating method, characterized in that, Including: Locally heating the inner wall of the oil pipe using an electromagnetic coil, and recording the temperature change of the inner wall of the oil pipe through a temperature probe at a position where the center of the electromagnetic coil closely adheres to the pipe wall of the oil pipe; Filling the inside of the oil pipe casing with water, and obtaining the relationship between the flow rate and the temperature change of the inner wall of the oil pipe when the water in the oil-casing annulus flows at different flow rates; Selecting measurement points, heating the oil pipe, and obtaining the corresponding flow rate outside the pipe based on the relationship between the flow rate and the temperature change of the inner wall of the oil pipe.

2. The method for detecting the flow rate of fluid outside the pipe using electromagnetic heating method according to claim 1, characterized in that A rubber ring seal is provided at the contact position between the electromagnetic coil and the inner wall.

3. A method for detecting the flow rate of an external fluid of a pipe using electromagnetic heating, as claimed in claim 1, wherein The temperature probe is closely adhered to the pipe wall of the oil pipe by pushing.

4. A method for detecting the flow rate of fluid outside a pipe using electromagnetic heating method according to claim 1, characterized in that, The temperature probe is wrapped with heat insulation material and completely separated from the water flow inside the pipe.

5. A method for detecting the flow rate of fluid outside a pipe using electromagnetic heating method according to claim 1, characterized in that, The electromagnetic coil uses a three-core cable, and each cable core realizes one function. The heating and pushing functions are realized using negative electricity. Different negative voltages are used for heating and pushing respectively, and positive voltage is used for measurement.

6. A method for detecting the flow rate of an external fluid of a pipe using electromagnetic heating, as claimed in claim 1, wherein The relationship between the flow rate and the temperature change of the inner wall of the oil pipe is the relationship between the equilibrium point temperature difference and the flow velocity outside the pipe.

7. A method for detecting the flow rate of an external fluid of a pipe using electromagnetic heating according to claim 6, characterized in that, The establishment process of the relationship between the equilibrium point temperature difference and the flow velocity outside the pipe is as follows: S1: Adjust the water flow velocity v to be stable; S2: Heat the oil pipe to obtain the temperature difference between the initial temperature and the equilibrium point temperature, which is the equilibrium point temperature difference ΔT; S3: Use multiple water flow velocities and execute S1 - S2 to form a two-dimensional relationship of v-ΔT.

8. A method for detecting the flow rate of fluid outside a pipe using electromagnetic heating method according to claim 1, characterized in that, The relationship between the flow rate and the temperature change of the inner wall of the oil pipe is the relationship between the time required to heat up to the same temperature and the flow velocity outside the pipe.

9. A method for detecting the flow rate of fluid outside a pipe using electromagnetic heating method according to claim 8, characterized in that, The establishment process of the relationship between the time required to heat up to the same temperature and the flow velocity outside the pipe is as follows: S1: Adjust the water flow velocity v to be stable and record the initial pipe wall temperature; S2: Heat the oil pipe while recording the pipe wall temperature until the temperature no longer rises; S3: Heat at the maximum flow rate to obtain the equilibrium temperature difference ΔT max , then heat the tubing wall to a temperature slightly lower than ΔT1 under other flow conditions, and through data processing, obtain the time Δt used from when the electromagnetic coil is powered on until the temperature reaches ΔT1 each time n , for Δt n and the flow velocity V n establish a relationship. By taking the derivative of the temperature change curve with respect to time under different flow conditions, a temperature increase extreme value DT can be obtained max , obtain DT max -V n relationship; S4: Starting from the time when the first inflection point of the derivative appears, obtain the relationship curve between the temperature rise difference of the water temperature and the required time under the condition that the water flow velocity v is constant; S5: Loop and execute the above S1 - S4 to obtain the relationship curve between the temperature rise difference of the water temperature and the required time at multiple water flow velocities when the electromagnetic power is P; S6: Change the electromagnetic power to P1, loop and execute the above S1 - S5 to obtain the relationship curve between the temperature rise difference of the water temperature and the required time at multiple water flow velocities when the electromagnetic power is P1, and form the relationship among the electromagnetic power, the water flow velocity outside the pipe, the temperature rise difference of the water temperature, and the required time.

10. A method for detecting the flow rate of fluid outside a pipe using electromagnetic heating method according to claim 1, characterized in that, The relationship between the flow rate and the temperature change of the inner wall of the oil pipe is the relationship between the heating temperature rise speed limit value and the flow velocity outside the pipe.

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