Oil and gas well temperature difference method flow measurement system and error correction method

Abstract

The present application relates to the field of downhole flow measurement, and mainly relates to an oil and gas well temperature difference method flow measurement system and an error correction method. The system forms an annular heating belt through constant temperature heating and pulse heating of a graphene heating module fixed on the outer wall of the oil pipe. In the process of heat energy transmission, the temperature at different positions is measured in real time by using the circumferentially arranged temperature sensors, and the test data of each temperature sensor is jointly processed, so that the error correction of the temperature measurement signal can be realized, the accuracy of the downhole flow test system of the temperature difference method is improved, the accurate measurement of the temperature in each direction outside the pipeline is realized, and the problem that the accurate temperature in each direction outside the pipeline cannot be obtained in the prior art is overcome.

Description

Technical Field

[0001] This invention relates to the field of downhole flow measurement, and mainly to an oil and gas well temperature difference flow measurement system and error correction method. Background Technology

[0002] Currently, downhole water injection technology in oilfields is mainly developing towards refined stratified water injection and automatic monitoring and control. Accurate measurement of the stratified water injection volume is a necessary condition for achieving refined stratified water injection and automatic monitoring and control. Currently, the flow meters used for downhole water injection flow measurement mainly include electromagnetic induction flow meters, turbine flow meters, vortex flow meters, differential pressure flow meters, and ultrasonic flow meters. However, under complex conditions such as high temperature and high pressure downhole, the measurement accuracy and durability of flow meters become difficult to control. Therefore, it is necessary to research a more adaptable and accurate flow detection method.

[0003] Since fluid flow is highly dependent on temperature changes, fluid flow rate can be measured by monitoring downhole temperature and utilizing the relationship between temperature and fluid velocity. Chinese invention patent CN110688612B discloses a method for predicting the production output of multi-layer oil wells using temperature logging data. This invention targets oil wells with multiple production layers. By analyzing the heat and mass transfer characteristics of the wellbore, formation, reservoir, and the coupling of multiple production layers in the wellbore, a comprehensive heat transfer model for multi-layer oil wells is established. Utilizing the differences in temperature variation patterns at different production layers, the flow rate distribution within the wellbore and the production output of each production layer are calculated based on actual temperature logging data. This solves the problem of insufficient prediction accuracy for single production layers caused by the use of average distribution methods in traditional well testing methods when dealing with multiple production layers.

[0004] Chinese utility model patent CN204944568U discloses a downhole flow measurement device that can be installed inside a downhole steam injection string. It includes: a cylindrical hollow shell with opposing first and second ends, the first end having a first opening and the second end having a second opening; a first temperature sensor located near the first end for measuring a first temperature of the fluid; a second temperature sensor located near the second end for measuring a second temperature of the fluid; a heat source located between the first and second temperature sensors for heating the fluid to be measured, creating a temperature difference between the first and second temperatures; and a data processing module for receiving the temperature difference and obtaining the flow rate of the fluid from the temperature difference.

[0005] Chinese patent application CN112212928A discloses a downhole whole-wellbore thermal flow measurement device. The device includes: a body placed in the fluid to be measured; a heater placed in the body, having a constant heating power for heating the body; a reference temperature sensor placed outside the body in the fluid to be measured; multiple measuring temperature sensors placed in the body at positions not in direct contact with the heater; the heat emitted by the heater dissipates within the body to form a spatial temperature gradient, and the multiple measuring temperature sensors are respectively located in different levels of the temperature gradient; and a conversion and power supply device for converting the measurement signals obtained by the temperature sensors into flow rate values ​​and supplying power to the heater.

[0006] Existing technologies only install one or a few temperature sensors at each depth, or use a single heating method. Although they can obtain the temperature at the depth where the sensor is located, the temperature information obtained is limited and can only reflect the temperature in the direction in which the sensor is installed. This is especially true for external heating flow measurement systems, which cannot obtain accurate temperatures in all directions outside the pipe, thus affecting the accuracy of flow measurement. Summary of the Invention

[0007] To address the above problems, this invention provides an oil and gas well flow rate measurement system based on temperature difference and a method for correcting temperature errors thereon. The system described in this invention has high flow rate measurement accuracy.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a flow measurement system for oil and gas wells using the temperature difference method, which includes a graphene heating module, a circuit module, and a temperature sensor module, all of which are fixed on the oil pipe. The graphene heating module includes an insulating heat insulation layer, a heating electrode, a protective electrode, a graphene layer, and a heat-conducting layer. The graphene layer is coated on the surface of the heat-conducting 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 heat-conducting layer containing the graphene layer.

[0010] Furthermore, the system includes several graphene heating modules, which are combined to form an annular heating belt, fixed to the outer wall of the oil pipe.

[0011] Furthermore, the temperature sensor measurement module includes several temperature sensor groups, with different temperature sensor groups fixed at intervals on the outer wall of the oil pipe.

[0012] Furthermore, each temperature sensor group includes several temperature sensors, and the temperature sensors within each temperature sensor group are arranged in a circle.

[0013] Furthermore, the temperature sensor is a PT1000 platinum resistance temperature sensor.

[0014] Furthermore, the circuit module includes a main control circuit, a temperature sensor nonlinear compensation circuit, a signal acquisition circuit, and a signal processing circuit. The main control circuit is used to control the on and off of the graphene heating pulse, the transmission of control signals, and the transmission of test signals. The temperature sensor nonlinear compensation circuit is used to compensate for the nonlinear change in the resistance of the platinum resistance as the temperature increases. The signal acquisition circuit is used to acquire the test signal from the temperature sensor after nonlinear compensation. The signal processing circuit is used to preprocess the array temperature signal, correct the error of the temperature data, and finally obtain the accurate flow rate through temperature-flow rate inversion interpretation.

[0015] This invention also provides an error correction method for the above-described oil and gas well temperature difference flow measurement system, comprising the following steps:

[0016] Constant heating and pulsed heating are applied to the graphene heating module respectively; test data of the temperature sensor module are acquired. The temperature sensor module includes several temperature sensor groups, which are fixed at intervals on the outer wall of the oil pipe to monitor the temperature at different depths in the oil pipe; the average temperature monitored by the temperature sensor group at each depth is calculated; the temperature difference change in different detection areas of the oil pipe at different depths is calculated; the calculated actual temperature and temperature difference are substituted into the temperature difference flow rate formula to calculate the flow rate under different heating methods; the distribution of fluid in each direction of the pipeline is analyzed; and the monitoring signals of individual temperature sensors in the temperature sensor group are compensated and corrected.

[0017] Furthermore, the flow rate under constant temperature heating is:

[0018] Q1=W / (ρC p ΔT)

[0019] 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.

[0020] Furthermore, the flow rate under pulse heating is:

[0021] Q2=(L / Δt)*π(d / 2) 2

[0022] In the formula, L is the distance between the two depth points, Δt is the time taken for the heating pulse to reach the peak temperature, and d is the pipe diameter.

[0023] The two methods described above can complement and correct temperature changes on the timeline by detecting the micro temperature difference ΔT under constant temperature heating and the time Δt taken to reach the peak temperature under pulse heating.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The system described in this invention uses a graphene heating module fixed to the outer wall of the oil pipe to form an annular heating band for constant temperature heating and pulse heating. During the heat transfer process, temperature sensors arranged in a circular pattern are used to measure the temperature at different locations in real time. The test data from each temperature sensor are jointly processed to correct the error of the temperature measurement signal, thereby improving the accuracy of the downhole flow rate testing system using the temperature difference method. This enables accurate measurement of the temperature in all directions outside the pipeline, thus overcoming the problem that existing technologies cannot obtain accurate temperatures in all directions outside the pipeline.

[0026] The system described in this invention has few electrical components, a long service life, and high measurement accuracy, and has broad application prospects. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the oil and gas well temperature difference flow measurement system described in this invention;

[0028] Figure 2 This is a schematic diagram of the graphene heating module in the oil and gas well temperature difference flow measurement system of the present invention;

[0029] Figure 3 This is a flowchart of the error correction method for the oil and gas well temperature difference flow measurement system described in Embodiment 3 of the present invention.

[0030] In the diagram, 1. Oil pipe, 2. Graphene heating module, 3. Circuit module, 4. Temperature sensor module, 201. Insulation layer, 202. Heating electrode, 203. Protective electrode, 204. Graphene heating band, 205. Thermal conductive layer. 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 oil and gas well temperature difference flow measurement system includes a graphene heating module 2, a circuit module 3, and a temperature sensor module 4, with each module fixed to the outer wall of the oil pipe 1.

[0036] like Figure 2 As shown, the graphene heating module 2 includes an insulating and heat-insulating layer 201, a heating electrode 202, a protective electrode 203, a graphene layer 204, and a heat-conducting layer 205. The graphene heating strip 204 is fixed to the surface of the heat-conducting layer 205. Heating electrodes 202 are provided at both ends of the graphene layer 204, and a protective electrode 203 is provided on one side of the graphene layer 204. The insulating and heat-insulating layer 201 covers the side of the heat-conducting layer 205 containing the graphene layer 204.

[0037] The system includes several graphene heating modules 2, which are combined to form an annular heating belt, fixed to the outer wall of the oil pipe 1.

[0038] The temperature sensor measurement module 4 includes 10 temperature sensor groups, which are fixed at intervals on the outer wall of the oil pipe; used to monitor the temperature at different depths in the oil pipe. Each temperature sensor group includes 16 temperature sensors, which are arranged circumferentially within each group. The temperature sensors are PT1000 platinum resistance temperature sensors.

[0039] The circuit module includes a main control circuit, a temperature sensor nonlinear compensation circuit, a signal acquisition circuit, and a signal processing circuit. The main control circuit is used to control the on and off of the graphene heating pulse, send control signals, and upload test signals. The temperature sensor nonlinear compensation circuit is used to compensate for the nonlinear change in the resistance of the platinum resistance as the temperature increases. The signal acquisition circuit is used to acquire the test signal from the temperature sensor after nonlinear compensation. The signal processing circuit is used to preprocess the array temperature signal, correct the temperature data error, and finally obtain the accurate flow rate through temperature-flow rate inversion.

[0040] Example 2

[0041] like Figure 1 As shown, the oil and gas well temperature difference flow measurement system includes a graphene heating module 2, a circuit module 3, and a temperature sensor module 4, with each module fixed to the outer wall of the oil pipe 1.

[0042] like Figure 2As shown, the graphene heating module 2 includes an insulating and heat-insulating layer 201, a heating electrode 202, a protective electrode 203, a graphene layer 204, and a heat-conducting layer 205. The graphene heating strip 204 is fixed to the surface of the heat-conducting layer 205. Heating electrodes 202 are provided at both ends of the graphene layer 204, and a protective electrode 203 is provided on one side of the graphene layer 204. The insulating and heat-insulating layer 201 covers the side of the heat-conducting layer 205 containing the graphene layer 204.

[0043] The system includes several graphene heating modules 2, which are combined to form an annular heating belt, fixed to the outer wall of the oil pipe 1.

[0044] The temperature sensor measurement module 4 includes three temperature sensor groups, which are fixed at intervals on the outer wall of the oil pipe; these groups are used to monitor the temperature at different depths within the oil pipe. Each temperature sensor group includes eight temperature sensors, which are arranged circumferentially within each group. The temperature sensors are PT1000 platinum resistance temperature sensors.

[0045] The circuit module includes a main control circuit, a temperature sensor nonlinear compensation circuit, a signal acquisition circuit, and a signal processing circuit. The main control circuit is used to control the on and off of the graphene heating pulse, send control signals, and upload test signals. The temperature sensor nonlinear compensation circuit is used to compensate for the nonlinear change in the resistance of the platinum resistance as the temperature increases. The signal acquisition circuit is used to acquire the test signal from the temperature sensor after nonlinear compensation. The signal processing circuit is used to preprocess the array temperature signal, correct the temperature data error, and finally obtain the accurate flow rate through temperature-flow rate inversion.

[0046] Example 3

[0047] like Figure 3 As shown, taking the oil and gas well temperature difference flow measurement system described in Example 2 as an example, the error correction method of the oil and gas well temperature difference flow measurement system includes the following steps:

[0048] Step 1. Apply constant heating and pulse heating to the graphene heating module respectively;

[0049] Step 2. Obtain test data from the temperature sensor module. The temperature sensor module includes three temperature sensor groups, each of which includes eight pt1000 platinum resistance temperature sensors. The temperature sensors are arranged in a circle and distributed on the outer wall of the oil pipe. The depth positions of the three temperature sensor groups are A, B and C, respectively.

[0050] Step 3. Calculate the average temperature monitored by the temperature sensor group at each depth:

[0051] Taking the temperature sensor array at depth A as an example, the temperature of each element is denoted as T.A_1 T A_2 T A_3 T A_4 T A_5 T A_6 T A_7 and T A_8 When fluid flows past the location of this temperature sensor array, the test signals of each temperature sensor element may not be identical due to factors such as gravity and viscosity. The purpose of installing temperature sensors at this depth is to obtain the actual temperature at that depth. Therefore, by coherently accumulating the test data from the array sensors distributed on the outer wall of the oil pipe, the average temperature at this location can be obtained.

[0052] T A =(T A_1 +T A_2 +T A_3 +T A_4 +T A_5 +T A_6 +T A_7 +T A_8 ) / 8 (1)

[0053] Similarly, the average temperature at depths B and C can be expressed as

[0054] T B =(T B_1 +T B_2 +T B_3 +T B_4 +T B_5 +T B_6 +T B_7 +T B_8 ) / 8 (2)

[0055] T C =(T C_1 +T C_2 +T C_3 +T C_4 +T C_5 +T C_6 +T C_7 +T C_8 ) / 8 (3)

[0056] Step 4. Calculate the temperature difference changes in different detection areas at different depths of the tubing;

[0057] Because the eight temperature sensors, arranged in a circular pattern, divide the outer wall of the oil pipe into eight equal detection zones (360 degrees), the theoretical resolution angle value for each zone is...

[0058]

[0059] for The temperature differences in the region at points A and B, and at points B and C are respectively...

[0060] ΔT AB_1 =T B_1 -T A_1 (5)

[0061] ΔT BC_1 =T C_1 -T B_1 (6)

[0062] Obtain using the same method The temperature difference changes in each detection area are expressed as ΔT for the temperature difference changes of the array temperature sensor at points A and B, and at points B and C, respectively. AB_2 ΔT AB_3 ΔT AB_4 ΔT AB_5 ΔT AB_6 ΔT AB_7 ΔT AB_8 and ΔT BC_2 ΔT BC_3 ΔT BC_4 ΔT BC_5 ΔT BC_6 ΔT BC_7 ΔT BC_8 By comparing the temperature difference changes of each temperature sensor in each detection area, the actual temperature difference ΔT between points A and B, and between points B and C, can be determined. AB and ΔT BC Represented as:

[0063] ΔT AB =(ΔT) AB_1 +ΔT AB_2 +ΔT AB_3 +ΔT AB_4 +ΔT AB_5 +ΔT AB_6 +ΔT AB_7 +ΔT AB_8 ) / 8 (7)

[0064] ΔT BC =(ΔT) BC_1 +ΔT BC_2 +ΔT BC_3 +ΔT BC_4 +ΔT BC_5 +ΔT BC_6 +ΔT BC_7 +ΔT BC_8 ) / 8 (8).

[0065] Step 5. Substitute the calculated average temperature and temperature difference into the temperature difference flow rate formula to calculate the flow rate under different heating methods;

[0066] The flow rate under constant temperature heating is

[0067] Q1=W / (ρCpΔT) (9)

[0068] 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.

[0069] The flow rate under pulse heating is

[0070] Q2=(L / Δt)*π(d / 2) 2 (10)

[0071] In the formula, L is the distance between the two depth points, Δt is the time taken for the heating pulse to reach the peak temperature, and d is the pipe diameter.

[0072] Step 6. Analyze the fluid distribution in all directions of the pipeline;

[0073] Step 7. Compensate and correct the monitoring signals of individual temperature sensors within the temperature sensor group.

[0074] 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. An oil and gas well temperature differential flow measurement system, characterized by, The graphene heating module, the circuit module and the temperature sensor module are fixed on the oil pipe. The graphene heating module comprises an insulation and heat insulation layer, a heating electrode, a protection electrode, a graphene layer and a heat conduction layer. The graphene heating module comprises an insulation and heat insulation layer, a heating electrode, a protection electrode, a graphene layer and a heat conduction layer. The temperature sensor measuring module comprises a plurality of temperature sensor groups, and the different temperature sensor groups are fixed on the outer wall of the oil pipe at intervals. Each temperature sensor group comprises a plurality of temperature sensors, and the temperature sensors in each temperature sensor group are arranged in a circle. The circuit module comprises a main control circuit, a temperature sensor nonlinear compensation circuit, a signal acquisition circuit and a signal processing circuit.

2. The temperature differential flow measurement system for oil and gas wells of claim 1, wherein, The temperature sensor is a pt1000 platinum resistance temperature sensor.

3. The error correction method of the oil and gas well temperature differential flow rate measurement system according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: The graphene heating module is subjected to constant heating and pulse heating respectively; test data of the temperature sensor module are obtained, the temperature sensor module comprises a plurality of temperature sensor groups, the different temperature sensor groups are fixed on the outer wall of the oil pipe at intervals, and are used for monitoring the temperature at different depths of the oil pipe; the average temperature monitored by each depth temperature sensor group is calculated; the temperature difference change of different detection areas of the oil pipe at different depths is calculated; the calculated actual temperature and temperature difference are substituted into a temperature difference flow formula to calculate the flow under different heating modes; the distribution state of the fluid in each direction of the pipeline is analyzed; and the monitoring signals of the single temperature sensors in the temperature sensor group are compensated and corrected.

4. The error correction method of claim 3, wherein, The flow under constant temperature heating is: Q1 = W / (pC p ΔT) In the formula, W is the heating power, Cp is the specific heat capacity, p is the fluid density, and ΔT is the micro temperature difference.

5. The error correction method of claim 3, wherein, The flow under pulse heating is: Q2 = (L / Δt) * π(d / 2) 2 In the formula, L is the distance between two depth points, ∆t is the time experienced by the heating pulse to reach the peak temperature, and d is the pipeline diameter.

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