A downhole graphene thermal conduction temperature difference flow meter and its usage method

Abstract

This invention relates to the field of downhole fluid flow measurement technology, specifically to a downhole graphene thermal conductivity temperature difference flow meter and its usage method. It includes two adapters, two cable connectors, two heat insulation blocks, a heating bracket, a graphene heating strip, several temperature sensors, a protective housing, a circuit compartment, and temperature sensors. The first adapter, first cable connector, first heat insulation block, heating bracket, second heat insulation block, circuit compartment, second cable connector, and second adapter are sequentially connected and placed inside the protective housing. The graphene heating strip is fixed to the heating bracket. Several temperature sensors are respectively installed on the heating bracket, circuit compartment, and second cable connector. The flow meter of this invention can be used for layered measurement, is easy to use with other instruments, and offers high measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of downhole fluid flow measurement technology, and mainly to a downhole graphene thermal conduction temperature difference flow meter and its usage method. Background Technology

[0002] Once an oil reservoir enters its high water-cut phase, its heterogeneity becomes severe. Polymer flooding tertiary oil recovery technology can effectively improve reservoir recovery and production efficiency, thereby controlling water cut and mitigating ineffective circulation. Downhole flow meters used in polymer flooding need to meet requirements such as layered measurement capability in polymer injection wells or wells where polymer is encountered, a central channel for easy access to other measuring and adjusting instruments, reliability, durability, and high measurement accuracy. However, existing electromagnetic induction flow meters, turbine flow meters, vortex flow meters, and differential pressure flow meters become difficult to control in complex conditions such as polymer fluids, high downhole temperatures, and high pressures. Therefore, a more adaptable and accurate flow detection method is needed.

[0003] CN 105952435A discloses a vortex flow meter suitable for downhole oil and water wells. Downhole fluid flows through a straight pipe and generates a stable and strong vortex field with a vortex generator. The probe uses separate piezoelectric sensing elements. When the vortex separates, the resulting alternating lift force acts on the lower part of the probe. The deformation of the two piezoelectric elements under stress outputs an electrical signal, thereby accurately measuring the flow velocity of the downhole fluid. Its disadvantage is that the vortex flow meter occupies the central channel, making it impossible to access other measuring instruments.

[0004] CN 110455355A discloses an in-well electromagnetic flowmeter for water injection. Based on the principle of electromagnetic induction, when liquid flows through the electromagnetic flowmeter, it generates an electromotive force by cutting magnetic lines of force, thereby calculating the flow rate of the measured medium.

[0005] Its disadvantages include numerous downhole electrical components, which can easily cause data drift during long-term well-stayed testing, leading to increased measurement errors and a shorter lifespan.

[0006] CN 109696212B discloses a small-diameter differential pressure flow meter that designs the original single orifice plate flow channel of a large-diameter small orifice plate into multiple orifice plate flow channels of different sizes with small-diameter large orifice plate apertures, which are uniformly arranged in a ring space. The electronic differential pressure sensor calculates the sum of the flow rates of the multiple orifice plate flow channels by accumulating the flow, thus solving the problem of flow measurement in narrow spaces. When the fluid filling the pipe flows through the orifice plate, it will cause local contraction, which can easily cause shearing of the polymer.

[0007] Chinese patent application CN112212928A discloses a downhole whole-wellbore thermal flow measurement device. The device includes: a body placed in the fluid being measured; a heater placed within the body, possessing a constant heating power for heating the body; a reference temperature sensor placed outside the body within the fluid being measured; multiple measuring temperature sensors placed within the body at locations not in direct contact with the heater; the heat emitted by the heater dissipates within the body, forming a spatial temperature gradient, with the multiple measuring temperature sensors located in different levels of this temperature gradient; and a conversion and power supply device for converting the measurement signals acquired by the temperature sensors into flow rate values ​​and supplying power to the heater. This device, with its measuring body placed within the fluid being measured, is highly dependent on the properties of the well fluid, resulting in a short lifespan. Furthermore, the lack of a central channel prevents other testing tools from functioning properly.

[0008] The CN 203808979 U downhole turbine flow meter continuously drives a turbine to rotate using an electric motor. When fluid passes through the turbine, the fluid changes the turbine's rotational speed, and the sensor obtains the fluid flow rate by detecting the difference in alternating signals. This effectively avoids the situation where the turbine does not rotate when a small flow rate of fluid passes through, thus improving the measurement accuracy of the downhole turbine flow meter. The disadvantage is that the turbine is easily jammed by polymer solutions, dirt, and rust, leading to inaccurate measurements and affecting the test results.

[0009] Therefore, improvements are still needed for downhole flow meters used in polymer flooding. Summary of the Invention

[0010] The main objective of this invention is to provide a downhole graphene thermal conduction temperature difference flow meter and its usage method. The flow meter of this invention can be used for stratified measurement and has high measurement accuracy. Using the flow meter of this invention can keep the central channel unobstructed, which facilitates the use of other instruments.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] This invention provides a downhole graphene thermal conductivity temperature difference flow meter, comprising two adapters, two cable connectors, two heat insulation blocks, a heating bracket, a graphene heating module, several temperature sensors, a protective shell, a circuit compartment, and temperature sensors. The first adapter, first cable connector, first heat insulation block, heating bracket, second heat insulation block, circuit compartment, second cable connector, and second adapter are sequentially connected and housed within the protective shell. The graphene heating module is fixed to the heating bracket. Several temperature sensors are respectively installed on the heating bracket, the circuit compartment, and the second cable connector. The heat insulation blocks isolate the heat from the heating element through the metal pipe wall, avoiding increased temperature measurement errors at the temperature sensors. The circuit compartment is mainly used to mount various circuit boards.

[0013] Furthermore, the flow meter includes several graphene heating modules, which are combined to form an annular heating belt and fixed on a heating bracket.

[0014] Furthermore, the graphene heating module includes an insulating and heat-insulating layer, heating electrodes, a protective electrode, a graphene layer, and a thermally conductive layer. The graphene layer is coated on the surface of the thermally conductive layer, heating electrodes are disposed at both ends of the graphene layer, a protective electrode is disposed on one side of the graphene layer, and the insulating and heat-insulating layer covers the side of the thermally conductive layer containing the graphene layer. The graphene heating module can be subjected to constant-temperature heating or pulse heating.

[0015] Furthermore, the temperature sensors are arranged linearly.

[0016] Furthermore, the temperature sensor is a PT1000 platinum resistance temperature sensor.

[0017] The present invention also provides a method for using the downhole graphene thermal conduction temperature difference flow meter described above, wherein the graphene heating module in the flow meter is subjected to constant temperature heating and pulse heating, and the fluid flow rate is obtained based on the flow rate calculated under the two heating methods of constant temperature heating and pulse heating.

[0018] Furthermore, under constant temperature heating conditions, the formula for calculating the flow rate Q is:

[0019] Q = W / (CpρΔT)

[0020] In the formula, W is the heating power, Cp is the specific heat capacity, ρ is the fluid density, and ΔT is the micro-temperature difference.

[0021] Furthermore, under pulse heating conditions, the flow rate Q is calculated using the following formula:

[0022] Q = (L / Δt) * S

[0023] In the formula, L is the distance between two depth points, Δt is the time taken for the heating pulse to reach the peak temperature, and S is the cross-sectional area of ​​the pipe.

[0024] This method combines thermal diffusion and thermal pulse techniques. By heating a graphene heating module, the graphene disturbs the fluid temperature. A high-precision PT1000 platinum resistance temperature sensor measures the temperature at different locations in real time. Combined with diffusion time and pipe cross-sectional area, the downhole fluid flow rate can be identified, enabling online flow monitoring. Specifically: First, a pulse excitation is applied to the heating strip to generate a thermal pulse. The temperature of the heating strip changes due to the flow rate, allowing the flow rate value to be obtained. Second, constant heating ensures that the temperature of the graphene annular heating strip wrapped around the tubing is higher than the ambient temperature, transferring heat energy to the liquid. The heated fluid moves at a certain velocity, and the flow rate value is also obtained by measuring the fluid temperature change at a distance L from the heating device. These two methods complement and correct each other, resulting in accurate flow rate readings.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The downhole graphene thermal conduction temperature difference flowmeter described in this invention has a simple structure, can keep the central channel unobstructed, and is convenient for use with other instruments.

[0027] The flow meter of this invention uses a linear arrangement of several PT1000 platinum resistance temperature sensors to accurately detect the temperature at different locations. During use, by employing both constant-temperature heating and thermal pulse heating methods, more accurate flow rates can be obtained. The flow meter of this invention can be used for stratified measurement. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of a downhole graphene thermal conduction temperature difference flow meter.

[0029] Figure 2 The measurement process for downhole graphene thermal conduction temperature difference flowmeters;

[0030] 1. First adapter, 2. First cable connector, 3. First heat insulation block, 4. Heating bracket, 5. Graphene heating module, 6. First temperature sensor, 7. Second heat insulation block, 8. Sheath, 9. Second temperature sensor, 10. Circuit compartment, 11. Third temperature sensor, 12. Second cable connector, 13. Second adapter. Detailed Implementation

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, and / or combinations thereof.

[0033] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0034] Example 1

[0035] like Figure 1 As shown, the downhole graphene thermal conduction temperature difference flow meter includes a first adapter 1, a first cable connector 2, a first heat insulation block 3, a heating bracket 4, a graphene heating belt 5, a first temperature sensor 6, a first heat insulation block 7, a protective shell 8, a second temperature sensor 9, a circuit compartment 10, a third temperature sensor 11, a second cable connector 12, and a second adapter 13.

[0036] The first adapter 1 is connected to the first cable connector 2. The right end of the first cable connector 2 is connected to the first heat insulation block 3. The right end of the first heat insulation block 3 is connected to the heating bracket 4. The heating bracket 4 is equipped with a graphene heating belt 5 and a first temperature sensor 6. The right end of the heating bracket 4 is connected to the second heat insulation block 7. The right end of the second heat insulation block 7 is connected to the circuit compartment 10. The second temperature sensor 9 is installed on the base tube of the circuit compartment 10 through a threaded hole. The right end of the circuit compartment 10 is connected to the second cable connector 12. The third temperature sensor 11 is installed on the second cable connector 12 through a threaded hole. The right end of the second cable connector 12 is connected to the second adapter 13. The protective shell 8 wraps the first cable connector 2, the first heat insulation block 3, the heating bracket 4, the graphene heating belt 5, the first temperature sensor 6, the first heat insulation block 7, the protective shell 8, the second temperature sensor 9, the circuit compartment 10, the third temperature sensor 11, and the second cable connector 12 through threads at both ends.

[0037] The function of the first heat insulation block 3 and the second heat insulation block 7 is to isolate the heat of the heating part from the conduction through the metal pipe wall, so as to avoid increasing the temperature measurement error at the first temperature sensor 6, the second temperature sensor 9 and the third temperature sensor 11.

[0038] The first temperature sensor 6, the second temperature sensor 9, and the third temperature sensor 11 all use PT1000 platinum resistance temperature sensors with a temperature measurement range of -50℃ to 200℃. Their resistance increases linearly with temperature changes. The three temperature sensors are arranged linearly.

[0039] The circuit compartment 10 is mainly used to install various circuit boards, including the main control circuit, signal acquisition circuit and signal processing circuit.

[0040] Example 2

[0041] The difference from Example 1 is that the flow meter includes 10 pt1000 platinum resistance temperature sensors, which are arranged linearly. Everything else is the same as in Example 1.

[0042] Example 3

[0043] The difference from Example 1 is that the flow meter includes 30 pt1000 platinum resistance temperature sensors, which are arranged linearly. Everything else is the same as in Example 1.

[0044] Example 4

[0045] The method of using the downhole graphene thermal conduction temperature difference flowmeter described in Example 1:

[0046] The graphene heating module in the flow meter is subjected to constant temperature heating and pulse heating. Under constant temperature heating conditions, the flow rate Q is calculated using the following formula:

[0047] Q = W / (CpρΔT)

[0048] In the formula, W is the heating power, Cp is the specific heat capacity, ρ is the fluid density, and ΔT is the micro-temperature difference.

[0049] Under pulse heating conditions, the flow rate Q is calculated using the following formula:

[0050] Q = (L / Δt) * S

[0051] In the formula, L is the distance between two depth points, Δt is the time taken for the heating pulse to reach the peak temperature, and S is the cross-sectional area of ​​the pipe.

[0052] The fluid flow rate is obtained based on the flow rates calculated under both isothermal heating and pulse heating methods, specifically as follows: Figure 2 As shown.

[0053] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A downhole graphene thermal conduction temperature difference flow meter, characterized in that, It includes two adapters, two cable connectors, two heat insulation blocks, a heating bracket, a graphene heating module, several temperature sensors, a protective shell, a circuit compartment, and temperature sensors; the first adapter, the first cable connector, the first heat insulation block, the heating bracket, the second heat insulation block, the circuit compartment, the second cable connector, and the second adapter are connected in sequence and placed inside the protective shell; the graphene heating module is fixed on the heating bracket; several temperature sensors are respectively installed on the heating bracket, the circuit compartment, and the second cable connector; The flow meter includes several graphene heating modules, which are combined to form an annular heating belt and fixed on a heating bracket. The graphene heating module includes an insulating heat insulation layer, heating electrodes, protective electrodes, a graphene layer, and a thermally conductive layer. The graphene layer is coated on the surface of the thermally conductive layer, heating electrodes are set at both ends of the graphene layer, a protective electrode is set on one side of the graphene layer, and the insulating heat insulation layer covers the side of the thermally conductive layer containing the graphene layer. The temperature sensors are arranged linearly. The graphene heating module in the flow meter is subjected to constant temperature heating and pulse heating. The fluid flow rate is obtained based on the flow rate calculated under the two heating methods of constant temperature heating and pulse heating.

2. The downhole graphene thermal conduction temperature difference flowmeter according to claim 1, characterized in that, The temperature sensor is a PT1000 platinum resistance temperature sensor.

3. The method of using the downhole graphene thermal conductivity temperature difference flowmeter according to any one of claims 1-2, characterized in that, Under constant temperature heating conditions, the formula for calculating the flow rate Q is: Q=W / (CpρΔT) In the formula, W is the heating power, Cp is the specific heat capacity, ρ is the fluid density, and ΔT is the micro-temperature difference; Under pulse heating conditions, the flow rate Q is calculated using the following formula: Q=(L / Δt)*S In the formula, L is the distance between two depth points, Δt is the time taken for the heating pulse to reach the peak temperature, and S is the cross-sectional area of ​​the pipe.

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