Flow acquisition control system and method for CO2 injection well

Abstract

The invention belongs to the technical field of CO2 gas injection in oilfield exploitation, and relates to a flow collection control system and method for a CO2 injection well. A vortex shedding flowmeter body is connected with a Christmas tree through a first pipeline and a second pipeline, and the first pipeline and the second pipeline are communicated with each other; the vortex generating body is arranged in the vortex shedding flowmeter body and is detachably connected with the second pipeline; the piezoelectric sensor is arranged on the second pipeline; the actuator control valve is arranged on the vortex shedding flowmeter body and connected with the joint of the first pipeline and the second pipeline; the first pressure sensor is arranged on the second pipeline and is close to the front end of the actuator control valve; and the second pressure sensor is arranged on the second pipeline and is close to the rear end of the actuator control valve. The CO2 volume flow is adjusted through the actuator control valve, the constant mass flow in the CO2 injection process is achieved, and the situation that the injected CO2 rapidly rushes in along a high-permeability layer, and consequently the gas channeling phenomenon is caused is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of CO2 gas injection in oil field exploitation, and in particular relates to a flow acquisition control system and method for a CO2 injection well. Background Art

[0002] In the field of oil production, with the continuous development of oil fields, the decline in reservoir pressure has become one of the key factors restricting the high and stable production of oil fields. The reduction in reservoir pressure leads to a large amount of degassing of underground crude oil and an increase in crude oil viscosity, which in turn significantly reduces the production of oil wells, and even causes the phenomenon of stopping spraying and production. This not only leads to a large amount of dead oil remaining underground and unable to be mined, causing serious waste of resources, but also increases the economic cost and environmental risk of oil field development.

[0003] In order to effectively make up for the underground deficit formed after crude oil extraction, increase the reservoir pressure, thereby maintaining or increasing the oil well production, and achieving high and stable production and high recovery rate of the oil field, the industry generally adopts the method of injecting water into the formation. However, this traditional method has many problems in the application of low permeability reservoirs. First, the starting pressure of the water injection well is high, and as the water injection process proceeds, the formation and water injection pressures rise rapidly, which is particularly unfavorable for low permeability reservoirs with low permeability. Secondly, the water injection effect is often unsatisfactory in production wells, and the formation pressure and production decline rapidly, making it difficult to achieve the expected production increase effect. Finally, even if the production well shows a certain production increase effect in the early stage, the liquid production index will drop significantly over time, and the oil production will also decrease rapidly, which further limits the application effect of the water injection method.

[0004] In view of the above problems, oil companies began to explore new technical means to cope with the development difficulties of low permeability reservoirs. In this context, oil companies actively explored and practiced the gas injection process of injecting CO2 into the well (i.e. "CO2 flooding"). This process injects CO2 gas into the well and uses the solubility, expansion and viscosity reduction of CO2 to effectively improve the flow properties of crude oil and increase the reservoir pressure, thereby increasing the production and recovery rate of oil wells.

[0005] However, the "CO2 flooding" technology also faces challenges in practical applications. In particular, when the gas injection volume is not properly controlled, the injected CO2 will quickly advance along the high permeability layer, resulting in gas channeling. This will not only reduce the utilization efficiency of CO2, but may also damage the formation structure. Therefore, how to intelligently control the injection volume of CO2 according to changes in the formation pressure and temperature environment to achieve balanced gas injection has become the key to the successful application of the "CO2 flooding" technology. Summary of the invention

[0006] The object of the present invention is to provide a flow collection control system and method for a CO2 injection well.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] In a first aspect, the present application provides a flow collection and control system for a CO2 injection well, comprising:

[0009] The vortex flowmeter body is connected to the Christmas tree through a first pipeline and a second pipeline, and the first pipeline and the second pipeline are interconnected;

[0010] A vortex generator is disposed in the vortex flowmeter body and is detachably connected to the second pipeline;

[0011] A piezoelectric sensor is disposed on the second pipe;

[0012] an actuator control valve, which is arranged on the vortex flowmeter body and connected to the connection between the first pipeline and the second pipeline;

[0013] A first pressure sensor is arranged on the second pipeline and close to the front end of the actuator control valve;

[0014] A second pressure sensor is arranged on the second pipeline and close to the rear end of the actuator control valve;

[0015] A temperature sensor is arranged in a cavity on the vortex flowmeter body;

[0016] The vortex flowmeter head is connected with the piezoelectric sensor, the first pressure sensor, the second pressure sensor, the temperature sensor and the actuator control valve through a threading tube and a cavity. The vortex flowmeter head is provided with a control device.

[0017] Furthermore, the control device comprises:

[0018] MCU, arranged on the vortex flowmeter head and connected to the actuator control valve;

[0019] a pressure signal processing circuit connected to the first pressure sensor and the second pressure sensor;

[0020] A temperature signal processing circuit connected to the temperature sensor;

[0021] A valve position signal processing circuit connected to a valve position sensor in the actuator control valve;

[0022] A flow signal circuit connected to the piezoelectric sensor;

[0023] The pressure signal processing circuit, temperature signal processing circuit, valve position signal processing circuit and flow signal circuit are all connected to the MCU via an AD analog-to-digital conversion chip;

[0024] A control screen module connected to the MCU;

[0025] A control algorithm module connected to the MCU;

[0026] A remote transmission module, one end of which is connected to the MCU, and the other end of which is connected to a remote host computer;

[0027] The system power management circuit is respectively connected with the MCU, the pressure signal processing circuit, the temperature signal processing circuit, the valve position signal processing circuit, the flow signal circuit, the control screen module, the control algorithm module and the remote transmission module.

[0028] Furthermore, the temperature signal processing circuit comprises:

[0029] A first operational amplifier chip U1A, wherein the third pin of the first operational amplifier chip U1A is connected to a constant voltage source, the second pin of the first operational amplifier chip U1A is connected to the first pin of the first operational amplifier chip U1A, the first pin of the first operational amplifier chip U1A is sequentially connected in series with a first resistor R1, a second resistor R2 and a third resistor R3, the third resistor R3 is grounded, and the first resistor R1, the second resistor R2 and the third resistor R3 divide the voltage output by the first operational amplifier chip U1A to form a divided voltage VYL;

[0030] A first filter capacitor C1, one end of which is connected to the output voltage of the first operational amplifier chip U1A, and the other end of which is grounded;

[0031] A second operational amplifier chip U1B, wherein a fifth pin of the second operational amplifier chip U1B is connected to the divided voltage VYL, and a sixth pin of the second operational amplifier chip U1B and a seventh pin of the second operational amplifier chip U1B are both connected to the temperature sensor;

[0032] The temperature sensor is grounded via a fourth resistor R4, and a first voltage T+ and a second voltage T- at both ends of the temperature sensor are connected to an input pin of the AD analog-to-digital conversion chip.

[0033] Furthermore, the pressure signal processing circuit includes:

[0034] a third operational amplifier chip U2A, wherein the eleventh pin of the third operational amplifier chip U2A is connected to the constant voltage source, the third pin of the third operational amplifier chip U2A is connected to the divided voltage VYL, the second pin of the third operational amplifier chip U2A is grounded through a first current limiting resistor R5, the first pin of the third operational amplifier chip U2A is connected to the tenth pin of the first pressure sensor through a fifth resistor R6, the eleventh pin of the first pressure sensor is grounded through the first current limiting resistor R5, the twelfth pin of the first pressure sensor is connected to a third voltage NO+, the thirteenth pin of the first pressure sensor is connected to a fourth voltage NO-, and the third voltage NO+ and the fourth voltage NO- are connected to the input pin of the AD analog-to-digital conversion chip;

[0035] A fourth operational amplifier chip U2B, a fifth pin of the fourth operational amplifier chip U2B is connected to the divided voltage VYL, a sixth pin of the fourth operational amplifier chip U2B is grounded through a second current limiting resistor R7, a seventh pin of the fourth operational amplifier chip U2B is connected to the fourteenth pin of the second pressure sensor through a sixth resistor R8, a fifteenth pin of the second pressure sensor is grounded through a second current limiting resistor R7, and is connected to the sixth pin of the fourth operational amplifier chip U2B, a sixteenth pin of the second pressure sensor is connected to a fifth voltage WO+, a seventeenth pin of the second pressure sensor is connected to a sixth voltage WO-, and the fifth voltage WO+ and the sixth voltage WO- are connected to the input pin of the AD analog-to-digital conversion chip.

[0036] Furthermore, the flow signal circuit includes:

[0037] A fifth operational amplifier chip U3, wherein a third pin of the fifth operational amplifier chip U3 is connected to a first output signal Wj+ and a second output signal Wj- of the vortex flowmeter body;

[0038] A sixth operational amplifier chip U4A, wherein the third pin of the sixth operational amplifier chip U4A is connected to the sixth pin of the fifth operational amplifier chip U3;

[0039] A seventh operational amplifier chip U4B, wherein the sixth pin of the seventh operational amplifier chip U4B is connected to the first pin of the sixth operational amplifier chip U4A through a fifteenth resistor R17 and a sixteenth resistor R18;

[0040] An eighth operational amplifier chip U5A, wherein the second pin of the eighth operational amplifier chip U5A is connected to the seventh pin of the seventh operational amplifier chip U4B via an eleventh capacitor C12 and a twenty-second resistor R24;

[0041] An analog switch U6, wherein a first pin of the analog switch U6 is connected to a first pin of the eighth operational amplifier chip U5A;

[0042] A ninth operational amplifier chip U7, wherein the third pin of the ninth operational amplifier chip U7 is connected to the second pin of the analog switch U6, and the sixth pin of the ninth operational amplifier chip U7 is connected to the input pin of the AD analog-to-digital conversion chip.

[0043] Further, the control screen module includes a control mode selection component, an alarm component and a flow coefficient modification component;

[0044] The control mode selection component includes a constant current mode, a constant pressure mode and an opening mode;

[0045] The constant flow mode is used to feed back the measured flow value to the MCU, and the MCU adjusts the valve of the actuator control valve according to the flow value;

[0046] The constant pressure mode is used for the MCU to adjust the valve of the actuator control valve according to the flow value to maintain constant pressure;

[0047] The opening mode is used to control the opening of the actuator control valve to achieve a preset water injection volume or water inlet pressure;

[0048] The alarm component is used to observe the flow change through the host computer when the vortex flowmeter sends out an alarm signal;

[0049] The flow coefficient modification component is used to modify the coefficients K and B of the vortex flowmeter in the host computer to adjust the overall flow when the flow value exceeds a preset threshold, wherein K represents the linearity of the flow and B represents the degree of deviation from the flow 0 point.

[0050] Furthermore, a valve core is arranged in the body of the vortex flowmeter, a flow hole is arranged obliquely on the valve core, and an I-shaped rotating valve plate adapted thereto is arranged on the flow hole;

[0051] The vortex generator is a double vortex generator in the shape of a triangular prism and a cylindrical prism.

[0052] In a second aspect, the present application provides a control method for a flow acquisition control system for a CO2 injection well, comprising the following steps:

[0053] Obtain the pressure, temperature and CO2 volume flow rate of the pipeline on the well to be tested;

[0054] According to the pressure and temperature, the CO2 density value is obtained based on the three-dimensional model of temperature-pressure-density and the isobaric coefficient table lookup method;

[0055] The mass flow rate of CO2 is calculated based on the CO2 volume flow rate and CO2 density value on the well;

[0056] The mass flow rate of CO2 is compared with the preset target mass flow rate of CO2. If there is a deviation between the mass flow rate of CO2 and the preset target mass flow rate of CO2, the volume flow rate of CO2 is adjusted by an adaptive integral separation PID control algorithm to achieve a constant mass flow rate during the CO2 injection process.

[0057] Furthermore, the step of constructing the temperature-pressure-density three-dimensional model includes:

[0058] Obtain CO2 density data analysis and calculation model;

[0059] According to the CO2 density data analysis calculation model, the function coefficients and intercept coefficients corresponding to different isobars are determined;

[0060] The three-dimensional model of temperature-pressure-density is determined according to the function coefficients and intercept coefficients corresponding to different isobars.

[0061] Further, the volume flow rate of CO2 is adjusted by the adaptive integral separation PID control algorithm, comprising the following steps:

[0062] Determining the volume flow rate of CO2 to be injected according to the mass flow rate of CO2;

[0063] Determining a volume flow rate deviation according to the volume flow rate of the CO2 to be injected and the volume flow rate of the current daily CO2 injection;

[0064] The adaptive integral separation PID control algorithm is used to adjust the valve opening of the actuator control valve according to the volume flow deviation to adjust the volume flow of CO2.

[0065] The present invention adopts the above technical solution, which has the following advantages:

[0066] The flow collection control system and method for CO2 injection wells of the present invention, when the oil production well is performing CO2 oil recovery operation, during the CO2 liquid injection process, the data in the pipeline is measured by the first pressure sensor, the second pressure sensor and the temperature sensor, and the measured data is transmitted to the control device in the vortex flowmeter head through the threading pipe. The control device processes these data, calculates the actual mass flow of CO2, and adjusts the CO2 volume flow through the actuator control valve according to the preset parameters and instructions to achieve the purpose of CO2 volume flow control, so as to achieve the constant mass flow during the CO2 injection process, and avoid the rapid advance of CO2 along the high permeability layer during the injection, resulting in the occurrence of gas channeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a schematic diagram of the structure of the vortex flowmeter body in the flow acquisition and control system for CO2 injection wells of the present invention.

[0068] Figure 2 It is a schematic diagram of the valve core structure of a vortex flowmeter in a flow acquisition control system for a CO2 injection well according to the present invention.

[0069] Figure 3 It is a schematic diagram of the structure of a rotary valve plate of a vortex flowmeter in a flow acquisition control system for a CO2 injection well according to the present invention.

[0070] Figure 4 It is a structural diagram of triangular and cylindrical vortex generators in the flow acquisition control system for CO2 injection wells of the present invention.

[0071] Figure 5 It is a block diagram of a control device in a flow acquisition control system for a CO2 injection well of the present invention.

[0072] Figure 6 The present invention is a temperature signal processing circuit diagram in a flow acquisition control system for a CO2 injection well.

[0073] Figure 7 This is a pressure signal processing circuit diagram in a flow acquisition control system for a CO2 injection well according to the present invention.

[0074] Figure 8 The present invention is a flow signal circuit diagram in a flow acquisition control system for a CO2 injection well.

[0075] Fig. 9 The present invention is a flow chart of the collection control operation of a vortex flowmeter for a flow collection control system of a CO2 injection well.

[0076] Fig.10 The present invention is an anti-interference circuit diagram for a flow acquisition control system for a CO2 injection well.

[0077] Fig.11 It is an operation flow chart of the flow rate collection and control method for CO2 injection wells of the present invention.

[0078] The figure numbers are as follows: 1-vortex flowmeter body, 101-first pipeline, 102-second pipeline, 103-cavity, 104-valve core, 105-flow hole, 106-rotating valve plate, 2-vortex generator, 3-piezoelectric sensor, 4-first pressure sensor, 5-temperature sensor, 6-second pressure sensor, 7-drive shaft, 8-threading pipe, 9-vortex flowmeter head, 10-actuator control valve, 11-coupling, 12-flange, 13-anti-rotation hole. DETAILED DESCRIPTION

[0079] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings so that the purpose, features and advantages of the present invention can be more clearly understood. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0080] The present invention provides a flow collection and control system for a CO2 injection well, specifically Figure 1 As shown, it includes a vortex flowmeter body 1, a vortex generator 2, a piezoelectric sensor 3, a first pressure sensor 4, a second pressure sensor 6, a temperature sensor 5, an actuator control valve 10 and a vortex flowmeter head 9; the vortex flowmeter body 1 is connected to the Christmas tree through a first pipeline 101 and a second pipeline 102, and the first pipeline 101 and the second pipeline 102 are interconnected; the vortex generator 2 is arranged in the vortex flowmeter body 1 and is detachably connected to the second pipeline 102; the piezoelectric sensor 3 is arranged on the second pipeline 102; the actuator control valve 10 is arranged on the vortex flowmeter body 1 and is connected to the first pipeline 101 is connected to the connection point of the second pipeline 102; the first pressure sensor 4 is arranged on the second pipeline 102 and is close to the front end of the actuator control valve 10; the second pressure sensor 6 is arranged on the second pipeline 102 and is close to the rear end of the actuator control valve 10; the temperature sensor 5 is arranged in the cavity 103 on the vortex flowmeter body 1; the vortex flowmeter head 9 is connected to the piezoelectric sensor 3, the first pressure sensor 4, the second pressure sensor 6, the temperature sensor 5 and the actuator control valve 10 through the threading tube 8 and the cavity 103, and a control device is arranged on the vortex flowmeter head 9.

[0081] In this embodiment, when the oil well is undergoing CO2 flooding operation, the CO2 liquid enters the vortex flowmeter system (i.e., the vortex flowmeter body 1) through the Christmas tree, and enters through the first pipeline 101 and the second pipeline 102. Among them, the second pipeline 102 is the main measurement channel. When the CO2 liquid passes through the vortex generator 2, the vibration of these vortices will cause the deformation of the piezoelectric sensor 3, and then generate an electrical signal, that is, the piezoelectric sensor 3 converts this mechanical vibration into an electrical signal output. The first pressure sensor 4 measures the pressure at the front end of the valve, and the second pressure sensor 6 measures the pressure at the rear end of the valve to monitor the state of the CO2 liquid. The temperature sensor 5 measures the temperature in the vortex flowmeter body because the temperature affects the flow measurement accuracy. The data collected by the piezoelectric sensor 3, the first pressure sensor 4, the second pressure sensor 6 and the temperature sensor 5 are transmitted to the control device in the vortex flowmeter head 9 through the threading tube 8 and the cavity 103. The control device processes these data, calculates the actual mass flow of CO2, and adjusts the volume flow of CO2 through the actuator control valve 10 according to the preset parameters or external instructions. When it is detected that the CO2 volume flow rate deviates from the set value, the control device will send a signal to the actuator control valve 10 to adjust the valve opening, thereby changing the fluid flow through the vortex flowmeter body to achieve the purpose of CO2 volume flow control, so as to achieve a constant mass flow rate during CO2 injection and avoid rapid advancement along the high permeability layer during CO2 injection, which may lead to gas channeling.

[0082] Furthermore, the vortex flowmeter body is connected to the first pipe and the second pipe respectively through two flanges 12, and a double-layer sealing ring is added at the connection to meet the sealing performance under high-pressure conditions; the piezoelectric sensor 3 is fixed to the surface of the second pipe 102 by screws; the first pressure sensor 4 and the second pressure sensor 6 are assembled on the second pipe 102 by threaded fixing; the temperature sensor 5 is inserted into the cavity 103; the actuator control valve 10 is connected to the vortex flowmeter body by screws and nuts.

[0083] In one embodiment, Figure 2 As shown, it is a valve core structure diagram of the vortex flowmeter. A valve core 104 is arranged in the vortex flowmeter body 1, and a flow hole 105 is obliquely arranged on the valve core 104.

[0084] As a preferred embodiment, the flow hole 105 is designed to be inclined to reduce pressure loss and increase measurement accuracy.

[0085] like Figure 3 , which is a structural diagram of the rotary valve plate 106 , and the rotary valve plate 106 is adapted to the flow hole 105 .

[0086] As a preferred embodiment, the rotary valve disc 106 adopts an "I"-shaped structure, which is mainly adapted for use with the flow hole 105. The rotary valve disc material is selected from high-pressure and high-temperature resistant stainless steel 9Cr18. The rotary valve disc 106 uses wear-resistant materials and improves the structural design of the valve core flow hole and the rotary valve disc, thereby enhancing the wear resistance of the valve core, extending the service life and improving the reliability of the range. In addition, the control device is used to achieve precise control of the valve core, and the valve core state is automatically adjusted according to the fluid characteristics and flow requirements, thereby improving the adaptability of the range and the measurement accuracy.

[0087] By optimizing the valve core design in this embodiment, the range of the vortex flowmeter can be effectively improved to meet the flow measurement requirements in different application scenarios, overcome the problems of limited adjustment range of the vortex flowmeter, inaccurate small flow measurement, large pipeline interference, etc., and make the flow regulation more accurate.

[0088] Furthermore, the actuator control valve 10 includes an actuator header, a coupling 11, and a transmission shaft 7; the actuator header is arranged on the top of the vortex flowmeter body, one end of the coupling 11 is connected to the actuator header, and the other end thereof is connected to the transmission shaft 7, the transmission shaft 7 extends into the vortex flowmeter body and is installed in cooperation with the anti-rotation hole 13 in the valve core, and is connected to the rotary valve plate 106. The anti-rotation hole is installed in cooperation with one end of the transmission shaft, and this cooperation mode limits the circumferential rotation of the transmission shaft, so that the transmission shaft moves along the axial direction, thereby ensuring the stability and accuracy of the valve core during the opening and closing process.

[0089] When the actuator control valve is working, when the external control signal acts on the actuator head, the actuator head converts the signal into a mechanical action, and this mechanical action is transmitted to the transmission shaft 7 through the coupling 11. The transmission shaft 7 further transmits the received power or signal to the rotary valve plate 106. The rotary valve plate 106 performs corresponding actions according to the power or signal transmitted by the transmission shaft to achieve the blocking or opening operation of the valve.

[0090] In one embodiment, specifically Figure 4 As shown, the vortex generator 2 is a double vortex generator in the shape of a triangular prism and a cylindrical prism.

[0091] Furthermore, the vortex generator is fixed in the vortex flowmeter body by selecting suitable bolts, nuts and sealing gaskets, and the shape and distance between the vortex generators can be flexibly designed according to different working conditions. The vortex generator is detachably connected to the second pipe, and can measure the medium of pipelines with different cross-sectional areas to adapt to different working conditions and ensure high-precision and high-reliability flow measurement. For pipelines with different cross-sectional areas, the vortex flowmeter adapts to different pipeline diameters by adjusting the size and shape of the vortex generator. For large-diameter pipelines, larger vortex generators can be used, while for small-diameter pipelines, smaller vortex generators are required. In comparing the choice of vortex generator shapes, the cylindrical generator has a large Strouhal number and small pressure loss, and has good performance at low flow rates; the triangular prism generator has a large vortex intensity, a strong signal-to-noise ratio, and strong stability. Therefore, this embodiment combines the advantages of both and designs a double vortex generator structure that combines a triangular prism generator and a cylindrical generator. This structure has the advantages of both, making the signal output of the vortex flowmeter more stable and accurate, and the double vortex generator has a low signal-to-noise ratio, which comprehensively improves the accuracy and stability of flow measurement.

[0092] In one embodiment, Figure 5 As shown, the control device includes MCU (microcontroller unit), pressure signal processing circuit, temperature signal processing circuit, valve position signal processing circuit and flow signal circuit; MCU is set on the vortex flowmeter head 9 and connected to the actuator control valve 10; pressure signal processing circuit is connected to the first pressure sensor 4 and the second pressure sensor 6; temperature signal processing circuit is connected to the temperature sensor 5; valve position signal processing circuit is connected to the valve position sensor in the actuator control valve 10; flow signal circuit is connected to the piezoelectric sensor 3; pressure signal processing circuit, temperature signal processing circuit, valve position signal processing circuit and flow signal circuit are all connected to MCU through AD analog-to-digital conversion chip; SPI pin of MCU is connected to the output end of AD analog-to-digital conversion chip to realize the collection of pressure, temperature, CO2 volume flow and other data. Control panel module is connected to MCU; control algorithm module is connected to MCU; remote transmission module, one end is connected to MCU, and the other end is connected to a remote host computer; system power management circuit is respectively connected to MCU, pressure signal processing circuit, temperature signal processing circuit, valve position signal processing circuit, flow signal circuit, control panel module, control algorithm module and remote transmission module.

[0093] In the present invention, specifically Figure 1-5As shown, first, the first pressure sensor 4, the second pressure sensor 6, the temperature sensor 5, and the vortex flowmeter collect the pressure, temperature, valve opening, and CO2 volume flow rate in the pipeline on the well to be tested. After the system is powered on, the MCU starts to initialize. After the initialization is completed, the MCU starts to collect data such as pressure, temperature, valve opening, and CO2 volume flow rate, and stores the data such as pressure, temperature, valve opening, and CO2 volume flow rate in an external Flash chip to achieve local storage. After the MCU completes the data storage, it waits for the next collection. The MCU is connected to a storage management circuit through an SPI digital signal interface to store the collected pressure, temperature, CO2 volume flow rate, and other data in real time. These stored pressure, temperature, CO2 volume flow rate, and other data can be played back. The collected pressure, temperature, and CO2 volume flow rate are processed by the MCU, and the data is transmitted to the client data monitoring center through the remote host computer and the remote transmission module.

[0094] In one embodiment, Figure 6 As shown, the temperature signal processing circuit includes a first operational amplifier chip U1A, a first filter capacitor C1 and a second operational amplifier chip U1B; the third pin of the first operational amplifier chip U1A is connected to a constant voltage source, the second pin of the first operational amplifier chip U1A is connected to the first pin of the first operational amplifier chip U1A, the first pin of the first operational amplifier chip U1A is connected in series with a first resistor R1, a second resistor R2 and a third resistor R3 in sequence, the third resistor R3 is grounded, the first resistor R1, the second resistor R2 and the third resistor R3 divide the voltage output by the first operational amplifier chip U1A to form a divided voltage VYL; one end of the first filter capacitor C1 is connected to the output voltage of the first operational amplifier chip U1A, and the other end is grounded; the fifth pin of the second operational amplifier chip U1B is connected to the divided voltage VYL, the sixth pin of the second operational amplifier chip U1B and the seventh pin of the second operational amplifier chip U1B are both connected to a temperature sensor 5 (i.e., a temperature sensor JO); the temperature sensor 5 is grounded through a fourth resistor R4, and the first voltage T+ and the second voltage T- at both ends of the temperature sensor 5 are connected to the input pin of the AD analog-to-digital conversion chip.

[0095] In one embodiment, Figure 7As shown, the pressure signal processing circuit includes a third operational amplifier chip U2A and a fourth operational amplifier chip U2B; the eleventh pin of the third operational amplifier chip U2A is connected to the constant voltage source, the third pin of the third operational amplifier chip U2A is connected to the divided voltage VYL, the second pin of the third operational amplifier chip U2A is grounded through the first current limiting resistor R5, the first pin of the third operational amplifier chip U2A is connected to the tenth pin of the first pressure sensor 4 (i.e., the first pressure sensor P1) through the fifth resistor R6, the eleventh pin of the first pressure sensor 4 is grounded through the first current limiting resistor R5, and is connected to the second pin of the third operational amplifier chip U2A, the twelfth pin of the first pressure sensor 4 is connected to the third voltage NO+, the thirteenth pin of the first pressure sensor 4 is connected to the fourth voltage NO-, and the third voltage NO+ and the fourth voltage NO- are connected to the input pin of the AD analog-to-digital conversion chip.

[0096] The fifth pin of the fourth op amp chip U2B is connected to the divided voltage VYL, the sixth pin of the fourth op amp chip U2B is grounded through the second current limiting resistor R7, the seventh pin of the fourth op amp chip U2B is connected to the fourteenth pin of the second pressure sensor 6 (i.e., the second pressure sensor P2) through the sixth resistor R8, the fifteenth pin of the second pressure sensor 6 is grounded through the second current limiting resistor R7 and is connected to the sixth pin of the fourth op amp chip U2B, the sixteenth pin of the second pressure sensor 6 is connected to the fifth voltage WO+, the seventeenth pin of the second pressure sensor 6 is connected to the sixth voltage WO-, and the fifth voltage WO+ and the sixth voltage WO- are connected to the input pin of the AD analog-to-digital conversion chip.

[0097] In one embodiment, Figure 8As shown, the flow signal circuit includes a fifth operational amplifier chip U3, a sixth operational amplifier chip U4A, a seventh operational amplifier chip U4B, an eighth operational amplifier chip U5A, an analog switch U6 and a ninth operational amplifier chip U7; the third pin of the fifth operational amplifier chip U3 is connected to the first output signal Wj+ and the second output signal Wj- of the vortex flowmeter body through the first capacitor C2 and the second capacitor C3; the third pin of the fifth operational amplifier chip U3 is also connected in series with the seventh resistor R9 and the eighth resistor R10, and is also connected in parallel with 3.3V through the ninth resistor R11, the tenth resistor R12 and The voltage signal after the third capacitor C4 divides the voltage; the second pin of the feedback end of the fifth operational amplifier chip U3 is grounded through the eleventh resistor R13 and the fourth capacitor C5, and is connected to the sixth pin of the fifth operational amplifier chip U3 through the twelfth resistor R14 and the fifth capacitor C6, the sixth pin of the fifth operational amplifier chip U3 is connected in series with the thirty-sixth resistor R40 and the thirty-seventh resistor R41, the thirty-eighth resistor R42 and the sixteenth capacitor C18 are connected between the thirty-sixth resistor R40 and the thirty-seventh resistor R41, and the thirty-eighth resistor R42 and the sixteenth capacitor C18 are connected in parallel. The seventh pin and the eighth pin of the fifth operational amplifier chip U3 are connected to a 3.3V voltage, and the fourth pin of the fifth operational amplifier chip U3 is grounded. The feedback end of the fifth operational amplifier chip U3 adjusts the signal through the resistance values ​​of the eleventh resistor R13 and the twelfth resistor R14. Due to the existence of the fourth capacitor C5 and the fifth capacitor C6 feedback capacitors, the fifth operational amplifier chip U3 only amplifies the AC signal, and the DC signal remains unchanged, that is, the voltage signal of the sixth pin of the fifth operational amplifier chip U3 is the superposition of the voltage-divided signal and the amplified signal between Wj+ and Wj-.

[0098] The third pin of the sixth op amp chip U4A is connected to the sixth pin of the fifth op amp chip U3, the second pin of the sixth op amp chip U4A is grounded through the thirteenth resistor R15 and the sixth capacitor C7, and is connected to the first pin of the sixth op amp chip U4A through the fourteenth resistor R16 and the seventh capacitor C8; the eleventh pin of the sixth op amp chip U4A is grounded, and the fourth pin of the sixth op amp chip U4A is connected to a 3.3V voltage.

[0099] The sixth pin of the seventh operational amplifier chip U4B is filtered by a low-pass filter circuit composed of a fifteenth resistor R17 and an eighth capacitor C9, and then connected to the first pin of the sixth operational amplifier chip U4A through a sixteenth resistor R18; the sixth pin of the feedback end of the seventh operational amplifier chip U4B is also connected in parallel with a seventeenth resistor R19 and a ninth capacitor C10, the seventeenth resistor R19 is connected to a tenth capacitor C11, the tenth capacitor C11 is connected in series with two reverse-parallel first diodes D1 and second diodes D2 and an eighteenth resistor R20, and the eighteenth resistor R20 is grounded through the eighth capacitor C9; the two reverse-parallel first diodes D1 and second diodes D2 mainly play the role of limiting voltage and reverse voltage protection to prevent damage to the operational amplifier due to reverse power polarity or external interference. The fifth pin of the seventh operational amplifier chip U4B is connected to the nineteenth resistor R21, the twentieth resistor R22, and the twenty-first resistor R23; the twentieth resistor R22 is grounded, the twenty-first resistor R23 is connected to a 3.3V voltage, and the seventh pin of the seventh operational amplifier chip U4B is connected to the second pin of the eighth operational amplifier chip U5A through the eleventh capacitor C12 and the twenty-second resistor R24. The seventh pin of the seventh operational amplifier chip U4B converts the sine signal into a rectangular wave signal, which is then filtered by the eleventh capacitor C12.

[0100] The second pin of the eighth operational amplifier chip U5A is connected to the seventh pin of the seventh operational amplifier chip U4B, the third pin of the eighth operational amplifier chip U5A is connected to the twenty-third resistor R25, the twenty-fourth resistor R26, and the twenty-fifth resistor R27, the twenty-fourth resistor R26 is grounded, and the twenty-fifth resistor R27 is connected to the 3.3V voltage; the third pin of the eighth operational amplifier chip U5A is connected to the first pin of the eighth operational amplifier chip U5A through the twenty-sixth resistor R28. The signal input to the in-phase terminal of the eighth operational amplifier chip U5A is a 3.3V voltage that is divided by the twenty-fourth resistor R26 and the twenty-fifth resistor R27, forming a reverse hysteresis comparator circuit as a whole to invert the rectangular wave signal.

[0101] The first pin of the analog switch U6 is connected to the first pin of the eighth operational amplifier chip U5A, the second pin of the analog switch U6 is connected to the ninth operational amplifier chip U7, the third pin of the analog switch U6 is grounded, and the fifth pin of the analog switch U6 is connected to a 5V voltage.

[0102] The third pin of the ninth operational amplifier chip U7 is connected to the second pin of the analog switch U6 through the bypass capacitor C13 and the pull-down resistor R29, and the second pin of the ninth operational amplifier chip U7 is connected to the sixth pin of the ninth operational amplifier chip U7 through the twenty-seventh resistor R30, and the ninth operational amplifier chip U7 and the twenty-seventh resistor R30 form a voltage follower circuit. The sixth pin of the ninth operational amplifier chip U7 is connected to the input pin of the AD analog-to-digital conversion chip, and the flow value is obtained through software algorithm processing. The sixth pin of the ninth operational amplifier chip U7 is grounded through the twenty-eighth resistor R31. The fourth pin of the ninth operational amplifier chip U7 is grounded, and one end of the seventh pin of the ninth operational amplifier chip U7 is connected to the 8V voltage, and the other end is grounded through the twelfth capacitor C14.

[0103] The first pin of the eighth operational amplifier chip U5A is electrically connected to the first pin of the analog switch U6. After passing through the analog switch U6, the output signal is a rectangular wave with processed frequency. After passing through the pull-down resistor R29 and the bypass capacitor C13, the signal enters the third pin of the ninth operational amplifier chip U7.

[0104] In one embodiment, the control screen module includes a control mode selection component, an alarm component and a flow coefficient modification component; the control mode selection component includes a constant flow mode, a constant pressure mode and an opening mode; the constant flow mode is used to feed back the measured flow value to the MCU, and the MCU adjusts the valve of the actuator control valve according to the flow value to achieve the constant flow mode. The constant pressure mode is used for the MCU to adjust the valve of the actuator control valve according to the flow value to maintain constant pressure. Although the vortex flowmeter measures the flow rate, there is a certain relationship between the flow rate and the pressure. Although the vortex flowmeter cannot directly control the pressure, it indirectly participates in the pressure control process by measuring the flow rate. When it is necessary to maintain constant pressure, the MCU will adjust the pump speed or valve opening according to the flow measured by the vortex flowmeter to maintain pressure stability. The opening mode is used to control the opening of the actuator control valve to achieve the preset opening water injection volume or water inlet pressure; the alarm component is used to observe the flow change through the host computer when the vortex flowmeter sends an alarm signal; the flow coefficient modification component is used to modify the coefficients K and B of the vortex flowmeter in the remote host computer when the flow value exceeds the preset threshold to adjust the overall flow, where K represents the linearity of the flow and B represents the degree of deviation from the flow 0 point.

[0105] In this embodiment, Fig. 9As shown, the pressure, temperature, CO2 volume flow rate and valve opening of the pipeline on the well to be measured are collected through pressure sensors, temperature sensors and vortex flowmeters, and the vortex flowmeter is observed to alarm. When no alarm occurs, the CO2 volume flow fluctuation is observed to be more than 1 cubic meter / day through the display screen or the remote host computer. When it exceeds, the damping coefficient of the vortex flowmeter is modified on the remote host computer to stabilize the measured flow within 1 cubic meter / day. When it does not exceed, measure whether the deviation between the instantaneous flow value and the actual CO2 volume flow exceeds θ (which can be set according to actual needs). When the deviation exceeds θ, the coefficients K and B of the vortex flowmeter are modified on the remote host computer to adjust the overall flow rate to be too large or too small. When the deviation does not exceed θ, the constant flow mode, constant pressure mode and opening mode are selected according to the actual working conditions to keep the flow stable. When the temperature and pressure change, the density of CO2 is calculated according to the three-dimensional model of temperature-pressure-density (which can be referred to as the model), and the CO2 volume flow is adjusted in real time through the control algorithm module to achieve the purpose of balanced CO2 injection.

[0106] Furthermore, the signal processing of the vortex flowmeter adopts the tracking filter and adaptive filter of the digital technology according to the characteristics of the signal and noise changes, and the spectrum characteristics of the signal and noise are analyzed by the spectrum analysis method to suppress the noise and extract the useful signal.

[0107] Furthermore, the vortex flowmeter adopts an anti-interference circuit design. Fig.10 The schematic diagram of the electrical signal anti-interference processing circuit is designed to resist external interference by processing the electrical signal and improve the accuracy of the measurement results.

[0108] like Fig.10 As shown, the anti-interference circuit design includes the tenth operational amplifier chip U8B, the eleventh operational amplifier chip U8A and the photoelectric isolator circuit U10; the fifth pin of the tenth operational amplifier chip U8B is grounded through the twenty-ninth resistor R32, the sixth pin is connected to the seventh pin of the tenth operational amplifier chip U8B through the thirtieth resistor R33 and the thirteenth capacitor C15 in parallel, and the sixth pin of the tenth operational amplifier chip U8B is also connected to the thirty-first resistor R34. The seventh pin of the tenth operational amplifier chip U8B is connected to the input end of the photoelectric isolator circuit U10.

[0109] The third pin of the eleventh operational amplifier chip U8A is connected to the output end of the photoelectric isolator circuit U10 through the thirty-second resistor R35 and the fourteenth capacitor C16; the fourteenth capacitor C16 is grounded. The second pin of the eleventh operational amplifier chip U8A is connected to the first pin of the eleventh operational amplifier chip U8A through the thirty-third resistor R36. The first pin of the eleventh operational amplifier chip U8A is connected to the input pin of the AD analog-to-digital conversion chip after voltage division through the thirty-fourth resistor R37 and the thirty-fifth resistor R38; one end of the thirty-fifth resistor R38 is grounded, and the other end is connected in parallel with the fifteenth capacitor C17. The fourth pin of the eleventh operational amplifier chip U8A is grounded. The eighth pin of the eleventh operational amplifier chip U8A is connected to voltage. The signal passes through the in-phase proportional amplifier circuit composed of the tenth operational amplifier chip U8B, which makes the input impedance high, the voltage gain large, the stability good and not easy to self-excite; the signal enters the optoelectronic isolator circuit U10 from the seventh pin of the tenth operational amplifier chip U8B, which makes the circuit have excellent electrical isolation performance, unidirectional signal transmission, strong anti-interference ability and fast response speed; the signal enters the low-pass filter circuit composed of the thirty-second resistor R35 and the fourteenth capacitor C16 from the output end of the optoelectronic isolator circuit U10, which can effectively remove the high-frequency noise in the signal, retain the low-frequency component of the signal, suppress noise, reduce errors, and amplify the signal under specific circumstances; then enters the voltage follower circuit composed of the eleventh operational amplifier chip U8A, which makes the common mode rejection ratio high, the bandwidth wide, simple and stable, and the anti-interference ability strong; finally, the signal is output through the first pin of the eleventh operational amplifier chip U8A, and then enters the AD analog-to-digital conversion chip for further processing after being divided by the thirty-fourth resistor R37 and the thirty-fifth resistor R38.

[0110] The present invention also provides a control method for a flow acquisition control device for a CO2 injection well, specifically as follows Fig.11 As shown, the following steps are included:

[0111] Step 1: Obtain the pressure, temperature and CO2 volume flow rate of the pipeline on the well to be tested;

[0112] During the entire process of CO2 injection into the well, the pressure, temperature and CO2 volume flow rate in the pipeline on the well to be tested need to be monitored in real time. Changes in the pressure and temperature of the pipeline on the well will cause changes in the CO2 density. According to the CO2 mass conservation principle, the CO2 mass flow rate must be accurately calculated.

[0113] Step 2: According to the pressure and temperature, the CO2 density value is obtained based on the three-dimensional model of temperature-pressure-density and the isobaric coefficient table lookup method;

[0114] The steps of constructing the temperature-pressure-density three-dimensional model include:

[0115] Step 2.1: Obtain CO2 density data analysis and calculation model;

[0116] Step 2.2: According to the CO2 density data analysis calculation model, determine the function coefficients and intercept coefficients corresponding to different isobars;

[0117] Step 2.3: Determine the three-dimensional model of temperature-pressure-density based on the function coefficients and intercept coefficients corresponding to different isobars.

[0118] The present invention establishes a three-dimensional model of temperature-pressure-density and uses the isobaric coefficient table lookup method to obtain the density value of CO2. A CO2 density data analysis and calculation model is provided based on engineering experience. The function coefficients and intercept coefficients of different isobars are obtained through model analysis. Since the function coefficients and intercept coefficients are nonlinear, a two-dimensional data table Factor[a][b] of the function coefficients and intercept coefficients corresponding to different isobars is established. When used, the two-dimensional data table is queried through the measured pressure value to obtain the corresponding function coefficient a i and the intercept coefficient b i , thereby calculating the CO2 density value at the current pressure and temperature. The CO2 density value calculation formula is: ρ = T*a i +b i , where T is the temperature. The CO2 density value at the current pressure and temperature is calculated through the model, and the CO2 mass flow rate is obtained according to the CO2 volume flow rate on the well. In order to keep the CO2 mass flow rate constant, the CO2 volume flow rate is adjusted according to the change of CO2 density to ensure balanced injection of CO2.

[0119] Step 3: Calculate the mass flow rate of CO2 based on the CO2 volume flow rate and CO2 density value on the well;

[0120] Step 4: Compare the mass flow rate of CO2 with the preset target mass flow rate of CO2. If there is a deviation between the mass flow rate of CO2 and the preset target mass flow rate of CO2, the volume flow rate of CO2 is adjusted by the adaptive integral separation PID control algorithm to achieve a constant mass flow rate during the CO2 injection process.

[0121] Specifically, the volume flow rate of CO2 is adjusted by an adaptive integral separation PID control algorithm, including the following steps:

[0122] Step 4.1: Determine the volume flow rate of CO2 to be injected according to the mass flow rate of CO2;

[0123] Since the pressure in the well remains unchanged, the mass flow rate of CO2 injected into the well must be maintained constant. The density of CO2 at this time is multiplied by the volume flow rate of CO2 to obtain the mass flow rate of CO2, which is then compared with the target mass flow rate of CO2 required on the well.

[0124] Step 4.2: Determine the volume flow rate deviation according to the volume flow rate of the CO2 to be injected and the volume flow rate of the current daily CO2 injection;

[0125] Step 4.3: By using the adaptive integral separation PID control algorithm, the valve opening of the actuator control valve is adjusted according to the volume flow deviation to adjust the volume flow of CO2.

[0126] Furthermore, let the mass flow rate of CO2 to be injected be m, let the volume flow rate of CO2 to be injected be V0 = m / ρ, let the volume flow rate of CO2 injected on the current day be Vi, then the volume flow rate deviation is ε = Vi-V0, with this as the deviation, the opening of the actuator control valve is controlled according to the CO2 volume flow rate deviation through the adaptive integral separation PID control algorithm to control the flow rate to V0. When the flow rate is constant, the mass flow rate of CO2 is obtained by multiplying the volume flow rate of CO2 and the density value at this time, and the deviation from the set value is kept within the allowable range.

[0127] The present invention discloses a flow collection and control method for a CO2 injection well. In the process of injecting CO2 into the well, a vortex flowmeter measures the pressure, temperature and CO2 volume flow of a pipeline on the well to be measured, and obtains the CO2 density value according to the pressure and temperature based on a three-dimensional model of temperature-pressure-density and an isobaric coefficient table lookup method. The mass flow rate of CO2 can be calculated through the density value to ensure that the mass flow rate of CO2 remains unchanged, thereby achieving balanced injection of CO2.

[0128] The present invention discloses a flow collection and control system for a CO2 injection well. The remote transmission module integrated in a vortex flowmeter can transmit the pressure, temperature, CO2 volume flow, valve opening and other data collected by a first pressure sensor, a second pressure sensor, a temperature sensor, a vortex flowmeter and a valve position sensor to a remote host computer. The remote host computer displays the data in real time and can remotely observe the changes in various parameters of the oil production well, so as to judge the injection amount of CO2 and the working conditions on the well. The remote host computer realizes data collection, remote data transmission and data processing by controlling a control device, controls the valve opening to adjust the flow rate, ensures accurate injection of CO2 and avoids the occurrence of gas channeling.

Claims

1. A flow collection and control system for a CO2 injection well, characterized in that: include: A vortex flowmeter body (1) is connected to a Christmas tree via a first pipeline (101) and a second pipeline (102), wherein the first pipeline (101) and the second pipeline (102) are in communication with each other; A vortex generating body (2) is arranged in the vortex flowmeter body (1) and is detachably connected to the second pipe (102); A piezoelectric sensor (3) is arranged on the second pipe (102); An actuator control valve (10) is arranged on the vortex flowmeter body (1) and connected to a connection point between the first pipeline (101) and the second pipeline (102); A first pressure sensor (4) is arranged on the second pipeline (102) and is close to the front end of the actuator control valve (10); A second pressure sensor (6) is arranged on the second pipeline (102) and is close to the rear end of the actuator control valve (10); A temperature sensor (5) is arranged in a cavity (103) on the vortex flowmeter body (1); The vortex flowmeter head (9) is connected to the piezoelectric sensor (3), the first pressure sensor (4), the second pressure sensor (6), the temperature sensor (5) and the actuator control valve (10) through the threading tube (8) and the cavity (103), and the vortex flowmeter head (9) is provided with a control device.

2. The flow collection and control system for a CO2 injection well according to claim 1, characterized in that: The control device comprises: MCU, arranged on the vortex flowmeter head (9) and connected to the actuator control valve (10); A pressure signal processing circuit connected to the first pressure sensor (4) and the second pressure sensor (6); A temperature signal processing circuit connected to the temperature sensor (5); A valve position signal processing circuit connected to a valve position sensor in the actuator control valve (10); A flow signal circuit connected to the piezoelectric sensor (3); The pressure signal processing circuit, temperature signal processing circuit, valve position signal processing circuit and flow signal circuit are all connected to the MCU via an AD analog-to-digital conversion chip; A control screen module connected to the MCU; A control algorithm module connected to the MCU; A remote transmission module, one end of which is connected to the MCU, and the other end of which is connected to a remote host computer; The system power management circuit is respectively connected with the MCU, the pressure signal processing circuit, the temperature signal processing circuit, the valve position signal processing circuit, the flow signal circuit, the control screen module, the control algorithm module and the remote transmission module.

3. The flow collection and control system for a CO2 injection well according to claim 2, characterized in that: The temperature signal processing circuit comprises: A first operational amplifier chip U1A, wherein the third pin of the first operational amplifier chip U1A is connected to a constant voltage source, the second pin of the first operational amplifier chip U1A is connected to the first pin of the first operational amplifier chip U1A, the first pin of the first operational amplifier chip U1A is sequentially connected in series with a first resistor R1, a second resistor R2 and a third resistor R3, the third resistor R3 is grounded, and the first resistor R1, the second resistor R2 and the third resistor R3 divide the voltage output by the first operational amplifier chip U1A to form a divided voltage VYL; A first filter capacitor C1, one end of which is connected to the output voltage of the first operational amplifier chip U1A, and the other end of which is grounded; A second operational amplifier chip U1B, a fifth pin of the second operational amplifier chip U1B is connected to the divided voltage VYL, and a sixth pin of the second operational amplifier chip U1B and a seventh pin of the second operational amplifier chip U1B are both connected to the temperature sensor (5); The temperature sensor (5) is grounded via a fourth resistor R4, and a first voltage T+ and a second voltage T− at both ends of the temperature sensor (5) are connected to an input pin of the AD analog-to-digital conversion chip.

4. The flow collection and control system for a CO2 injection well according to claim 2 is characterized in that: The pressure signal processing circuit comprises: a third operational amplifier chip U2A, wherein the eleventh pin of the third operational amplifier chip U2A is connected to a constant voltage source, the third pin of the third operational amplifier chip U2A is connected to a divided voltage VYL, the second pin of the third operational amplifier chip U2A is grounded via a first current limiting resistor R5, the first pin of the third operational amplifier chip U2A is connected to the tenth pin of the first pressure sensor (4) via a fifth resistor R6, the eleventh pin of the first pressure sensor (4) is grounded via the first current limiting resistor R5, the twelfth pin of the first pressure sensor (4) is connected to a third voltage NO+, the thirteenth pin of the first pressure sensor (4) is connected to a fourth voltage NO-, and the third voltage NO+ and the fourth voltage NO- are connected to the input pin of the AD analog-to-digital conversion chip; A fourth operational amplifier chip U2B, a fifth pin of the fourth operational amplifier chip U2B is connected to the divided voltage VYL, a sixth pin of the fourth operational amplifier chip U2B is grounded via a second current limiting resistor R7, a seventh pin of the fourth operational amplifier chip U2B is connected to a fourteenth pin of the second pressure sensor (6) via a sixth resistor R8, a fifteenth pin of the second pressure sensor (6) is grounded via the second current limiting resistor R7 and is connected to the sixth pin of the fourth operational amplifier chip U2B, a sixteenth pin of the second pressure sensor (6) is connected to a fifth voltage WO+, a seventeenth pin of the second pressure sensor (6) is connected to a sixth voltage WO-, and the fifth voltage WO+ and the sixth voltage WO- are connected to the input pin of the AD analog-to-digital conversion chip.

5. The flow collection and control system for a CO2 injection well according to claim 3 is characterized in that: The flow signal circuit comprises: A fifth operational amplifier chip U3, wherein a third pin of the fifth operational amplifier chip U3 is connected to a first output signal Wj+ and a second output signal Wj- of the vortex flowmeter body; A sixth operational amplifier chip U4A, wherein the third pin of the sixth operational amplifier chip U4A is connected to the sixth pin of the fifth operational amplifier chip U3; A seventh operational amplifier chip U4B, wherein the sixth pin of the seventh operational amplifier chip U4B is connected to the first pin of the sixth operational amplifier chip U4A through a fifteenth resistor R17 and a sixteenth resistor R18; An eighth operational amplifier chip U5A, wherein the second pin of the eighth operational amplifier chip U5A is connected to the seventh pin of the seventh operational amplifier chip U4B through an eleventh capacitor C12 and a twenty-second resistor R24; An analog switch U6, wherein a first pin of the analog switch U6 is connected to a first pin of the eighth operational amplifier chip U5A; A ninth operational amplifier chip U7, wherein the third pin of the ninth operational amplifier chip U7 is connected to the second pin of the analog switch U6, and the sixth pin of the ninth operational amplifier chip U7 is connected to the input pin of the AD analog-to-digital conversion chip.

6. The flow collection and control system for a CO2 injection well according to claim 5, characterized in that: The control screen module includes a control mode selection component, an alarm component and a flow coefficient modification component; The control mode selection component includes a constant current mode, a constant pressure mode and an opening mode; The constant flow mode is used to feed back the measured flow value to the MCU, and the MCU adjusts the valve of the actuator control valve according to the flow value; The constant pressure mode is used for the MCU to adjust the valve of the actuator control valve according to the flow value to maintain constant pressure; The opening mode is used to control the opening of the actuator control valve to achieve a preset water injection volume or water inlet pressure; The alarm component is used to observe the flow change through the host computer when the vortex flowmeter sends out an alarm signal; The flow coefficient modification component is used to modify the coefficients K and B of the vortex flowmeter in the host computer to adjust the overall flow when the flow value exceeds a preset threshold, wherein K represents the linearity of the flow and B represents the degree of deviation from the flow 0 point.

7. The flow collection and control system for a CO2 injection well according to claim 6, characterized in that: A valve core (104) is arranged in the vortex flowmeter body (1), a flow hole (105) is arranged obliquely on the valve core (104), and an I-shaped rotating valve plate (106) adapted thereto is arranged on the flow hole (105); The vortex generator (2) is a double vortex generator in the shape of a triangular prism and a cylindrical prism.

8. A control method for a flow acquisition control system for a CO2 injection well using the flow acquisition control system according to any one of claims 1 to 7, characterized in that: The following steps are involved: Obtain the pressure, temperature and CO2 volume flow rate of the pipeline on the well to be tested; According to the pressure and temperature, the CO2 density value is obtained based on the three-dimensional model of temperature-pressure-density and the isobaric coefficient table lookup method; The mass flow rate of CO2 is calculated based on the CO2 volume flow rate and CO2 density value on the well; The mass flow rate of CO2 is compared with the preset target mass flow rate of CO2. If there is a deviation between the mass flow rate of CO2 and the preset target mass flow rate of CO2, the volume flow rate of CO2 is adjusted by an adaptive integral separation PID control algorithm to achieve a constant mass flow rate during the CO2 injection process.

9. The control method according to claim 8, characterized in that: The steps of constructing the temperature-pressure-density three-dimensional model include: Obtain CO2 density data analysis and calculation model; According to the CO2 density data analysis calculation model, the function coefficients and intercept coefficients corresponding to different isobars are determined; The three-dimensional model of temperature-pressure-density is determined according to the function coefficients and intercept coefficients corresponding to different isobars.

10. The control method according to claim 9, characterized in that: The method of adjusting the volume flow of CO2 by using an adaptive integral separation PID control algorithm comprises the following steps: Determining the volume flow rate of CO2 to be injected according to the mass flow rate of CO2; Determining a volume flow rate deviation according to the volume flow rate of the CO2 to be injected and the volume flow rate of the current daily CO2 injection; The adaptive integral separation PID control algorithm is used to adjust the valve opening of the actuator control valve according to the volume flow deviation to adjust the volume flow of CO2.

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