A high-temperature and high-pressure downhole differential pressure flow measurement method and system

Abstract

A kind of high temperature high pressure downhole differential pressure flow measurement method and system, specific steps include: S1, data preprocessing stage: acquisition original pressure data and temperature data, original pressure data is corrected using temperature compensation algorithm to ambient temperature, obtain real-time pressure data;S2, according to the pressure value in real-time pressure data of internal pressure and hole behind, the difference value of internal pressure before throttle hole and hole behind pressure behind throttle hole is calculated, and real-time differential pressure data is obtained;S3, initial flow value is converted to real-time differential pressure data using iterative algorithm, and final flow value is obtained by using cubic polynomial fitting model to nonlinear correction initial flow value.The beneficial effects of the present application are: the present application is suitable for non-standard aperture differential pressure flowmeter in high temperature high pressure downhole, real-time acquisition of pressure data is realized by designing high temperature resistant pressure data acquisition system to obtain differential pressure, and national standard flow algorithm is compensated and corrected by cubic polynomial, so that the error between flow measurement result and actual flow is not more than 3%.

Description

Technical Field

[0001] This invention relates to the field of downhole flow measurement technology in high-temperature and high-pressure environments, and more specifically to a method and system for measuring differential pressure flow in high-temperature and high-pressure downhole environments. Background Technology

[0002] Downhole environments are typically characterized by large temperature gradients (from room temperature to 125°C) and high pressures (up to 60 MPa), which pose a significant risk of failure for electronic devices.

[0003] According to the national standard GB / T2624-93, this standard is only applicable to operating conditions where the pipe inner diameter (D) is in the range of 50 mm to 1000 mm and the orifice diameter (d) of the throttling device is not less than 12.5 mm. This standard is no longer applicable to orifice diameter measurements outside the above parameter range.

[0004] Therefore, there is an urgent need for a solution that can ensure the accuracy and reliability of measurement results to meet the metrological needs under non-standard working conditions. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a method and system for measuring differential pressure flow rate in high-temperature and high-pressure downhole wells.

[0006] A method for measuring flow rate by differential pressure in high-temperature and high-pressure wells, comprising the following steps: S1. Data preprocessing stage: Collect raw pressure data and temperature data, and use a temperature compensation algorithm to correct the raw pressure data for ambient temperature to obtain real-time pressure data; S2. Based on the pressure values ​​in the internal pressure and real-time pressure data after the orifice, calculate the difference between the internal pressure before the orifice and the pressure after the orifice to obtain the real-time pressure difference data. S3. The real-time differential pressure data is converted into an initial flow rate value using an iterative algorithm. The initial flow rate value is then nonlinearly corrected using a cubic polynomial fitting model to obtain the final flow rate value.

[0007] In S1, the average value filtering algorithm and the Butterworth filtering algorithm are used to filter the raw pressure data, extract the effective low-frequency pressure components, and then the filtered raw pressure data is corrected for ambient temperature.

[0008] The cubic polynomial of the cubic polynomial fitting model is: y=K3* +K2* +K1* +B Wherein, K3 is the coefficient of the cubic term; K2 is the coefficient of the quadratic term; K1 is the coefficient of the linear term; and B is the constant term. The coefficients of the cubic term K3, the quadratic term K2, the linear term K1, and the constant term B are obtained through flow calibration experiments.

[0009] The specific steps for S3 are as follows: S31. Define the initial Reynolds number and the initial flow coefficient; S32. Calculate the outflow coefficient value based on the initial Reynolds number; S33. Calculate the mass flow rate using the outflow coefficient value; S34. Update the Reynolds number value based on the current mass flow rate value; S35. Determine whether the current outflow coefficient and Reynolds number converge simultaneously; If the current outflow coefficient and Reynolds number converge simultaneously, then the current mass flow rate is taken as the final mass flow rate. If they do not converge simultaneously, the Reynolds number is updated based on the mass flow rate, and the outflow coefficient is recalculated until the Reynolds number and the outflow coefficient converge simultaneously to obtain the final mass flow rate. S36. Convert the final mass flow rate into volumetric flow rate, which is the preliminary calculation result; S37. Perform a cubic fitting correction on the volumetric flow rate to obtain the final accurate volumetric flow rate.

[0010] In S2, a differential pressure zeroing operation is performed when the flow rate is zero to eliminate system zero bias.

[0011] A high-temperature, high-pressure downhole differential pressure flow measurement system includes: a downhole working cylinder, a surface controller, and a host computer monitoring platform. The downhole working barrel is equipped with a temperature acquisition circuit, a pressure acquisition circuit, and a core processing unit (MCU). The temperature acquisition circuit and the pressure acquisition circuit are used to acquire temperature data and pressure data, respectively. The core processing unit (MCU) is used to receive the data acquired by the sensor and calculate the final flow rate value. The downhole working barrel uploads the pressure, temperature, and flow rate data to the surface controller. The ground controller is used to receive data transmitted by the downhole working barrel or control the movement of the downhole working barrel, and upload the data to the host computer monitoring platform; The host computer monitoring platform is used to visualize the data output.

[0012] The temperature acquisition circuit includes a thermistor and an operational amplifier. The thermistor and a pull-up resistor form a voltage divider circuit. The output of the voltage divider circuit is connected to the input of the operational amplifier. The output of the operational amplifier is connected to the 12-bit ADC channel of the core processing unit MCU. The inverting input of the operational amplifier is connected to the circuit connecting the output of the operational amplifier and the core processing unit MCU.

[0013] The pressure acquisition circuit includes: analog differential input signal nodes ADC1- and ADC1+ are connected to the inverting and non-inverting input terminals of an operational amplifier respectively through resistors. The output terminal of the operational amplifier is connected to the inverting input terminal through a feedback resistor, forming a closed-loop differential amplifier circuit. The output terminal of the operational amplifier is connected to the input terminal ADC1 of a high-temperature resistant AD analog-to-digital converter chip. The negative input terminal of the AD analog-to-digital converter chip is connected to analog ground GND, forming an analog signal input sampling architecture. The AD analog-to-digital converter chip converts the acquired analog signal into a digital signal. The AD analog-to-digital converter chip communicates digitally with the main control chip MCU via the SPI bus. The main control chip MCU acquires the pressure digital signal via the SPI bus.

[0014] The beneficial effects of this invention are as follows: This solution is applicable to differential pressure flowmeters with non-standard orifice diameters (D=44mm; d=7 / 12 / 16mm) in high-temperature and high-pressure wells. By designing a high-temperature and high-pressure data acquisition system, pressure data is collected in real time to obtain the differential pressure. Furthermore, the national standard flow algorithm is corrected by a third polynomial compensation, ensuring that the error between the flow measurement result and the actual flow does not exceed 3%. This achieves stability and accuracy under high-temperature and high-pressure environments. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating the working principle of a high-temperature, high-pressure downhole differential pressure flow measurement system. Figure 2 This is the circuit diagram of the temperature acquisition circuit; Figure 3 This is the circuit diagram of the pressure acquisition circuit; Figure 4 The circuit diagram for the core processing unit, MCU; Figure 5 A flowchart of a high-temperature, high-pressure downhole differential pressure flow measurement system; Figure 6 A flowchart of the process algorithm; Figure 7 This is a diagram showing the flow measurement effect of small displacement in Example 1; Figure 8 This is a diagram showing the effect of displacement flow rate measurement in Example 2; Figure 9 This is a diagram showing the effect of flow measurement for a large displacement vehicle in Example 3. Detailed Implementation

[0016] Example like Figure 5 As shown, a high-temperature, high-pressure downhole differential pressure flow measurement method includes the following steps: S1. Data preprocessing stage: Collect raw pressure data and temperature data, and use a temperature compensation algorithm to correct the raw pressure data for ambient temperature to obtain real-time pressure data; S2. Based on the pressure values ​​in the internal pressure and real-time pressure data after the orifice, calculate the difference between the internal pressure before the orifice and the pressure after the orifice to obtain the real-time pressure difference data. In S2, a differential pressure zeroing operation is performed when the flow rate is zero to eliminate system zero bias.

[0017] S3. The real-time differential pressure data is converted into an initial flow rate value using an iterative algorithm. The initial flow rate value is then nonlinearly corrected using a cubic polynomial fitting model to obtain the final flow rate value.

[0018] In S1, the average value filtering algorithm and the Butterworth filtering algorithm are used to filter the raw pressure data, extract the effective low-frequency pressure components, and then the filtered raw pressure data is corrected for ambient temperature.

[0019] The cubic polynomial of the cubic polynomial fitting model is: y=K3* +K2* +K1* +B Where K3 is the coefficient of the cubic term; K2 is the coefficient of the quadratic term; K1 is the coefficient of the linear term; and B is the constant term.

[0020] The coefficients K3 (cubic term), K2 (quadratic term), K1 (linear term), and B (constant term) were obtained through flow calibration experiments.

[0021] In this embodiment, the flow calibration experiment generates a standard actual flow value y using a standard flow meter. Using the initial flow value x calculated by the system through an iterative algorithm, multiple sets of (x, y) values ​​are fitted to obtain the coefficients K1, K2, K3, and the bias B. The obtained coefficients are then written into the core processing unit MCU, and the system calculates the actual flow value.

[0022] The flow rate calculated using this method is very close to the actual flow rate, thus achieving the goal of accurate flow rate measurement.

[0023] like Figure 6 As shown, the specific steps of S3 are as follows: S31. Define the initial Reynolds number and the initial flow coefficient; S32. Calculate the outflow coefficient value based on the initial Reynolds number; S33. Calculate the mass flow rate using the outflow coefficient value; S34. Update the Reynolds number value based on the current mass flow rate value; S35. Determine whether the current outflow coefficient and Reynolds number converge simultaneously; If the current outflow coefficient and Reynolds number converge simultaneously, then the current mass flow rate is taken as the final mass flow rate. If they do not converge simultaneously, the Reynolds number is updated based on the mass flow rate, and the outflow coefficient is recalculated until the Reynolds number and the outflow coefficient converge simultaneously to obtain the final mass flow rate. S36. Convert the final mass flow rate into volumetric flow rate, which is the preliminary calculation result; S37. Perform a cubic fitting correction on the volumetric flow rate to obtain the final accurate volumetric flow rate.

[0024] The following are test examples for small displacement, medium displacement, and large displacement engines, respectively, provided in this embodiment.

[0025] Example 1 The upstream pipe has an inner diameter of 44mm, a throttling orifice diameter of 7mm, and contains water. The working cylinder was tested in test well JJSY-2H, and the deviation between the measured data and the theoretical values ​​was controlled within 3%. Detailed test data are shown in Appendix 1, and the effect diagram is attached. Figure 7 As shown, this example verifies the high accuracy of the measurement system in the small displacement range.

[0026] Table 1. Small Displacement Test Data Example 2 The upstream pipe has an inner diameter of 44mm, a throttling orifice diameter of 12mm, and contains water. The working cylinder was tested in test well JJSY-2H. The deviation between the measured data and the theoretical values ​​was controlled within 3%. Detailed test data are shown in Appendix 2, and the effect diagram is attached. Figure 8 As shown, this example verifies the high accuracy of the measurement system in the medium displacement range.

[0027] Table 2 Displacement Test Data Example 3 The upstream pipe has an inner diameter of 44mm, a throttling orifice diameter of 16mm, and contains water. The working cylinder was tested in test well JJSY-2H. The deviation between the measured data and the theoretical values ​​was controlled within 3%. Detailed test data are shown in Appendix 3, and the effect diagram is attached. Figure 9 As shown in the figure. This example verifies the high accuracy of the measurement system over a wide displacement range.

[0028] Table 3. Large Displacement Test Data like Figure 1 As shown, a high-temperature, high-pressure downhole differential pressure flow measurement system includes: a downhole working cylinder, a surface controller, and a host computer monitoring platform. The downhole working barrel is equipped with a temperature acquisition circuit, a pressure acquisition circuit, and a core processing unit (MCU). The temperature acquisition circuit and the pressure acquisition circuit are used to acquire temperature data and pressure data, respectively. The core processing unit (MCU) is used to receive the data acquired by the sensor and calculate the final flow rate value. The downhole working barrel uploads the pressure, temperature, and flow rate data to the surface controller. The ground controller is used to receive data transmitted by the downhole working barrel or control the movement of the downhole working barrel, and upload the data to the host computer monitoring platform; The host computer monitoring platform is used to visualize the data output.

[0029] like Figure 2 As shown, the temperature acquisition circuit includes a thermistor and an operational amplifier. The thermistor and a pull-up resistor form a voltage divider circuit. The output of the voltage divider circuit is connected to the input of the operational amplifier. The output of the operational amplifier is connected to the 12-bit ADC channel of the core processing unit MCU. The inverting input of the operational amplifier is connected to the circuit connecting the output of the operational amplifier and the core processing unit MCU.

[0030] like Figure 3 and Figure 4 As shown, the pressure acquisition circuit includes: analog differential input signal nodes ADC1- and ADC1+ are connected to the inverting and non-inverting input terminals of an operational amplifier respectively through resistors. The output terminal of the operational amplifier is connected to the inverting input terminal through a feedback resistor, forming a closed-loop differential amplifier circuit. The output terminal of the operational amplifier is connected to the input terminal ADC1 of a high-temperature resistant AD analog-to-digital converter chip. The negative input terminal of the AD analog-to-digital converter chip is connected to analog ground GND, forming an analog signal input sampling architecture. The AD analog-to-digital converter chip converts the acquired analog signal into a digital signal and communicates digitally with the main control chip MCU through the SPI bus. The main control chip MCU acquires the pressure digital signal through the SPI bus.

[0031] Preferred, with Figure 4 For example, the SPI bus includes four pins: MISO, MOSI, SCLK, and SCB.

[0032] The operational amplifier's output is connected to its inverting input via a feedback resistor, forming a closed-loop differential amplifier circuit used for gain adjustment and common-mode rejection of the input signal. The AD converter chip communicates with the core processing unit (MCU) via an SPI serial peripheral interface, transmitting the converted digital pressure data to the MCU for reading, storage, and further processing of the pressure signal.

[0033] Preferably, the pressure sensor has a measurement range of 0–60 MPa, and the overall circuitry can withstand temperatures of not less than 125°C.

[0034] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for measuring flow rate by differential pressure in high-temperature and high-pressure downhole wells, characterized in that... The specific steps include: S1. Data preprocessing stage: Collect raw pressure data and temperature data, and use a temperature compensation algorithm to correct the raw pressure data for ambient temperature to obtain real-time pressure data; S2. Based on the pressure values ​​in the internal pressure and real-time pressure data after the orifice, calculate the difference between the internal pressure before the orifice and the pressure after the orifice to obtain the real-time pressure difference data. S3. The real-time differential pressure data is converted into an initial flow rate value using an iterative algorithm. The initial flow rate value is then nonlinearly corrected using a cubic polynomial fitting model to obtain the final flow rate value.

2. The high-temperature and high-pressure downhole differential pressure flow measurement method according to claim 1, characterized in that: In S1, the average value filtering algorithm and the Butterworth filtering algorithm are used to filter the raw pressure data, extract the effective low-frequency pressure components, and then the filtered raw pressure data is corrected for ambient temperature.

3. The high-temperature and high-pressure downhole differential pressure flow measurement method according to claim 1, characterized in that, The cubic polynomial of the cubic polynomial fitting model is: y=K3* +K2* +K1* +B Wherein, K3 is the coefficient of the cubic term; K2 is the coefficient of the quadratic term; K1 is the coefficient of the linear term; and B is the constant term. The coefficients of the cubic term K3, the quadratic term K2, the linear term K1, and the constant term B are obtained through flow calibration experiments.

4. The high-temperature and high-pressure downhole differential pressure flow measurement method according to claim 1, characterized in that, The specific steps for S3 are as follows: S31. Define the initial Reynolds number and the initial flow coefficient; S32. Calculate the outflow coefficient value based on the initial Reynolds number; S33. Calculate the mass flow rate using the outflow coefficient value; S34. Update the Reynolds number value based on the current mass flow rate value; S35. Determine whether the current outflow coefficient and Reynolds number converge simultaneously; If the current outflow coefficient and Reynolds number converge simultaneously, then the current mass flow rate is taken as the final mass flow rate. If they do not converge simultaneously, the Reynolds number is updated based on the mass flow rate, and the outflow coefficient is recalculated until the Reynolds number and the outflow coefficient converge simultaneously to obtain the final mass flow rate. S36. Convert the final mass flow rate into volumetric flow rate, which is the preliminary calculation result; S37. Perform a cubic fitting correction on the volumetric flow rate to obtain the final accurate volumetric flow rate.

5. The high-temperature, high-pressure downhole differential pressure flow measurement method according to claim 1, characterized in that: In S2, a differential pressure zeroing operation is performed when the flow rate is zero to eliminate system zero bias.

6. A high-temperature, high-pressure downhole differential pressure flow measurement system, used to perform the high-temperature, high-pressure downhole differential pressure flow measurement method as described in any one of claims 1-4, characterized in that, include: Downhole working barrel, ground controller and upper computer monitoring platform, The downhole working barrel is equipped with a temperature acquisition circuit, a pressure acquisition circuit, and a core processing unit (MCU). The temperature acquisition circuit and the pressure acquisition circuit are used to acquire temperature data and pressure data, respectively. The core processing unit (MCU) is used to receive the data acquired by the sensor and calculate the final flow rate value. The downhole working barrel uploads the pressure, temperature, and flow rate data to the surface controller. The ground controller is used to receive data transmitted by the downhole working barrel or control the movement of the downhole working barrel, and upload the data to the host computer monitoring platform; The host computer monitoring platform is used to visualize the data output.

7. The high-temperature, high-pressure downhole differential pressure flow measurement system according to claim 5, characterized in that, The temperature acquisition circuit includes a thermistor and an operational amplifier. The thermistor and a pull-up resistor form a voltage divider circuit. The output of the voltage divider circuit is connected to the input of the operational amplifier. The output of the operational amplifier is connected to the 12-bit ADC channel of the core processing unit MCU. The inverting input of the operational amplifier is connected to the circuit connecting the output of the operational amplifier and the core processing unit MCU.

8. A high-temperature, high-pressure downhole differential pressure flow measurement system according to claim 5, characterized in that, The pressure acquisition circuit includes: analog differential input signal nodes ADC1- and ADC1+ are connected to the inverting and non-inverting input terminals of an operational amplifier respectively through resistors. The output terminal of the operational amplifier is connected to the inverting input terminal through a feedback resistor, forming a closed-loop differential amplifier circuit. The output terminal of the operational amplifier is connected to the input terminal ADC1 of a high-temperature resistant AD analog-to-digital converter chip. The negative input terminal of the AD analog-to-digital converter chip is connected to analog ground GND, forming an analog signal input sampling architecture. The AD analog-to-digital converter chip converts the acquired analog signal into a digital signal. The AD analog-to-digital converter chip communicates digitally with the main control chip MCU via the SPI bus. The main control chip MCU acquires the pressure digital signal via the SPI bus.

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