A downhole multi-parameter online acquisition system and acquisition method for CO2 injection wells

Abstract

The present application relates to a kind of downhole multi-parameter online acquisition system and acquisition method for CO2 injection well, wherein the acquisition system includes surface controller and downhole measuring instrument, the surface controller and downhole measuring instrument are electrically connected by direct current carrier bus, the downhole measuring instrument is sequentially measured CO2 parameter data of injection well subzone by being placed into oil pipe, the surface controller carries out real-time monitoring and flow control to the CO2 parameter data of downhole measuring instrument acquisition by direct current carrier bus with direct current carrier communication mode, and the surface controller will be acquired CO2 parameter data real-time forwarding to host computer, and the CO2 injection allocation of the oil layer where downhole measuring instrument is located is obtained after being processed by the host computer.The CO2 parameter data of multiple oil layers can be tested by downhole measuring instrument once, and can be recycled multiple times.

Description

Technical Field

[0001] This invention belongs to the field of oilfield stratified gas injection technology, specifically relating to a downhole multi-parameter online acquisition system and acquisition method for CO2 injection wells. Background Technology

[0002] CO2 has enormous application potential in oil extraction. CO2 enhanced oil recovery (EOR) technology can reduce crude oil interfacial tension, decrease displacement resistance, lower crude oil viscosity, and promote crude oil volume expansion, thereby significantly increasing single-well production. Furthermore, by repeatedly recovering and injecting CO2 produced with the oil, net-zero CO2 emissions and permanent geological sequestration can ultimately be achieved. CO2 EOR technology is suitable for conventional reservoirs, especially low-permeability and ultra-low-permeability reservoirs, and can effectively improve crude oil recovery rates.

[0003] Currently, CO2 enhanced oil recovery (EOR) technology is still in the research stage in China, and its application is mainly in the experimental exploration phase. Because current CO2 injection processes use surface liquid CO2 injection, injecting gas into each oil layer indiscriminately, the different pressures, temperatures, and permeabilities of the oil layers cause CO2 to exhibit different phases, resulting in uncertain CO2 distribution. This leads to CO2 leakage along the direction of high permeability, causing gas channeling and failing to achieve effective gas-driven oil recovery. Furthermore, research on CO2 injection downhole profile distribution parameters is mostly still in the theoretical analysis and modeling simulation stage, making it impossible to actually obtain the downhole CO2 injection profile distribution parameters to provide technical reference for stratified gas injection technology. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a downhole multi-parameter online acquisition system and method for CO2 injection wells. This system utilizes a DC carrier bus to deploy downhole measuring instruments, and the ground controller achieves real-time online acquisition of multiple downhole CO2 parameters via DC carrier communication, thus solving the problem of being unable to obtain the downhole profile distribution parameters of CO2 injection wells.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A downhole multi-parameter online acquisition system for CO2 injection wells is characterized by comprising a surface controller and a downhole measuring instrument. The surface controller and the downhole measuring instrument are electrically connected via a DC carrier bus. The downhole measuring instrument is lowered into the tubing to sequentially measure CO2 parameter data of the injection well layers. The surface controller performs real-time monitoring and flow control of the CO2 parameter data acquired by the downhole measuring instrument via DC carrier communication through the DC carrier bus. Furthermore, the surface controller forwards the acquired CO2 parameter data to a host computer in real time. After processing by the host computer, the CO2 injection volume of the oil layer where the downhole measuring instrument is located is obtained.

[0007] Furthermore, the ground controller includes a ground power supply unit, a ground main control unit, a ground programmable control unit, and a carrier communication unit. The ground main control unit controls the carrier communication unit to communicate with the downhole measuring instrument via a DC carrier bus. The ground main control unit outputs a control signal to control the ground programmable control unit to output a current loop control signal to control the ground power supply unit to output an adjustable voltage power supply to the downhole measuring instrument. The ground main control unit also communicates with the host computer and receives instructions from the host computer for processing and response. The downhole measuring instrument includes a current collection section and a measurement section. The measurement section includes a measurement main control unit, a downhole signal acquisition unit, a measurement communication unit, a turbine signal measurement unit, and a pressure and temperature measurement unit for measuring CO2 parameter data. After the ground main control unit controls the measurement section to collect current, the turbine signal measurement unit and the pressure and temperature measurement unit transmit the measured CO2 parameter data to the measurement main control unit through the downhole signal acquisition unit. The measurement main control unit then uploads the acquired CO2 parameter data to the ground controller via the measurement communication unit using DC carrier communication.

[0008] Furthermore, the carrier communication unit includes a carrier encoding circuit and a carrier decoding circuit. The carrier encoding circuit outputs a normalized Mann code signal to the ground output unit based on the encoded control signal from the ground master control unit. The ground output unit loads the normalized Mann code signal onto a DC carrier bus and transmits it to the downhole measuring instrument. The carrier decoding circuit amplifies and converts the normalized Mann code signal received by the ground output unit according to the decoding gain set by the ground master control unit, and then outputs it to the ground master control unit for parsing and processing.

[0009] Furthermore, the current collecting short section and the measuring short section are threaded together. The current collecting short section includes a current collecting outer protective tube, inside which a motor unit and a lead screw assembly are installed. The lead screw assembly extends from the lower end of the current collecting outer protective tube and is connected to a leaf spring assembly. A current collecting rubber sleeve is fitted around the outer periphery of the leaf spring assembly. A current collecting flow channel is also provided at the lower end of the current collecting outer protective tube. The current collecting flow channel passes through the center of the leaf spring assembly and is connected to a current collecting lower connector. Several current collecting flow holes are radially arranged around the outer periphery of the current collecting flow channel. The motor unit controls the lead screw assembly to drive the leaf spring assembly to deform, bend, or straighten, thereby causing the current collecting rubber sleeve fitted on the leaf spring assembly to open or retract.

[0010] The measurement sub-section also includes a measurement outer casing and a measurement flow channel. The pressure and temperature measurement unit is installed at the lower end of the measurement flow channel, and a measurement outlet hole is provided on the outer periphery of the lower end of the measurement flow channel. The turbine signal measurement unit is installed inside the measurement flow channel. The measurement main control unit, downhole signal acquisition unit, and measurement communication unit are installed inside the measurement outer casing. After the flow is collected by the gas collector and the set tubing is opened, CO2 enters the flow collector channel from the flow collector outlet hole and then enters the measurement flow channel. After passing through the turbine signal measurement unit, it flows out from the measurement outlet hole. The turbine signal measurement unit transmits the measured turbine flow rate signal to the downhole signal acquisition unit. CO2 flows out from the measurement outlet hole and passes through the pressure and temperature measurement unit. The pressure and temperature measurement unit transmits the measured pressure and temperature signals of CO2 to the downhole signal acquisition unit.

[0011] Furthermore, an opening control unit and a closing control unit are also provided inside the current collector outer protective tube. The opening control unit and the closing control unit are electrically connected to the motor unit. The ground main control unit controls the ground program control unit to output negative power supply voltages of different amplitudes from the ground power supply unit to the DC carrier bus. The opening control unit and the closing control unit receive negative power supply voltages of different amplitudes through the DC carrier bus to control the motor unit to drive the lead screw assembly forward and backward, so as to control the current collector rubber tube to open and retract.

[0012] Furthermore, the turbine signal measurement unit includes a turbine blade assembly, a support assembly, and a detection assembly. The turbine signal measurement unit has a measurement flow channel, within which the turbine blade assembly is disposed. Support assemblies supporting the rotation of the turbine blade assembly are respectively disposed at both ends of the turbine blade assembly. The detection assembly is disposed within the measurement flow channel. When CO2 flows within the measurement flow channel, it drives the turbine blade assembly to rotate. The detection assembly measures the CO2 flow velocity by detecting the rotational speed of the turbine blade assembly.

[0013] Furthermore, a magnetic positioning measurement unit is also installed inside the outer protective tube. The magnetic positioning measurement unit collects the magnetic field change parameters of the oil pipe in real time and sends them to the measurement main control unit. The measurement main control unit uploads the collected magnetic field change parameters to the ground controller via a DC carrier bus through the measurement communication unit to determine the position of the oil pipe joint.

[0014] Furthermore, the magnetic positioning measurement unit includes a second magnet, a coil, and a coil support mechanism. The second magnet is respectively installed at both ends of the coil, and the coil support mechanism is installed at the lower end of the measuring outer protective tube to support the second magnet and the coil.

[0015] Furthermore, the measurement communication unit includes a measurement coding circuit and a measurement decoding circuit; the measurement master control unit controls the measurement coding circuit to communicate with the ground controller through the encoding of the returned-polarized Mann code sequence to realize the uploading of CO2 parameter data and the reply of various commands; the measurement master control unit receives the instructions sent by the ground controller from the measurement decoding circuit, processes them, and replies to the commands; the measurement coding circuit converts the returned-polarized Mann code encoded signal output by the measurement master control unit into a returned-polarized Mann code waveform and uploads it to the ground controller through a DC carrier bus; the measurement decoding circuit converts the returned-polarized Mann code waveform sent by the ground controller into a TTL level serial port signal and inputs it to the measurement master control unit.

[0016] Furthermore, the present invention also provides a downhole multi-parameter online acquisition method for CO2 injection wells, characterized by comprising the following steps:

[0017] Step S1: Place the downhole measuring instrument at the upper part of the injection device position of the tubing joint;

[0018] In step S2, the host computer sends a command to the ground controller to open the rubber tube. The ground controller controls the downhole measuring instrument to open the collecting rubber tube and set the oil pipe. The CO2 in the oil pipe passes through the internal flow channel of the downhole measuring instrument.

[0019] Step S3: CO2 flow rate is calculated when CO2 passes through the turbine signal measurement unit; CO2 temperature and pressure at the injection well location where the downhole measuring instrument is located are measured by the pressure and temperature measurement unit, and the CO2 injection amount in the oil layer is obtained by combining the CO2 flow rate.

[0020] In step S4, the host computer issues a command to close the rubber tube, and the ground controller controls the downhole measuring instrument to retract the collecting rubber tube.

[0021] Step S5: Continue to raise or lower the downhole measuring instrument and measure the CO2 injection volume of each oil layer in sequence according to steps S1-S3.

[0022] The present invention has the following advantages due to the adoption of the above technical solutions:

[0023] (1) The present invention provides a downhole multi-parameter online acquisition system and acquisition method for CO2 injection wells, which can be directly applied to the CO2 injection well environment without the need for reconstruction or modification, eliminating the hassle of going down into the well and having to start up the well again if there is a fault, saving costs. The downhole measuring instruments can be reused multiple times, and can be quickly brought out of the well if there is a fault, without affecting normal oil production.

[0024] (2) The present invention provides a downhole multi-parameter online acquisition system and acquisition method for CO2 injection wells, which can test multiple downhole CO2 parameters online and quickly obtain parameter changes and plot change curves to facilitate technical analysis. The downhole measuring instrument can acquire multiple layered parameters at the same time when it is deployed into the well.

[0025] (3) The present invention provides a downhole multi-parameter online acquisition system and acquisition method for CO2 injection wells. The ground controller and the downhole measuring instrument are powered and communicated bidirectionally through a DC carrier bus. The ground controller controls the downhole measuring instrument to perform flow collection measurement by outputting a negative power supply voltage. The CO2 flow rate is measured by turbine measurement method, and the actual CO2 injection amount is obtained by density compensation algorithm. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a downhole multi-parameter online acquisition system for CO2 injection wells according to the present invention.

[0027] Figure 2 This is a block diagram of the ground controller principle of the present invention.

[0028] Figure 3 This is a block diagram illustrating the principle of the downhole measuring instrument of the present invention.

[0029] Figure 4 This is a schematic diagram of the downhole measuring instrument structure of the present invention.

[0030] Figure 5 This is a schematic diagram of the current collection short section structure of the present invention.

[0031] Figure 6 This is a schematic diagram of the measuring section structure of the present invention.

[0032] Figure 7 This is a schematic diagram of the magnified structure of the turbine signal measurement unit of the present invention.

[0033] Figure 8 This is a flowchart of a downhole multi-parameter online acquisition method for CO2 injection wells according to the present invention.

[0034] The labels in the attached diagram are as follows:

[0035] 1. Ground controller; 1-1 Ground power supply unit; 1-2 Ground main control unit; 1-3 Ground program control unit; 1-4 Ground switching unit; 1-5 Carrier communication unit; 1-6 Ground acquisition unit; 1-7 Polarity switching switch; 1-8 Ground communication unit; 1-9 Ground output unit;

[0036] 2. Downhole measuring instruments; 2-1. Combustion manifold; 2-1-1. Open control unit; 2-1-2. Close control unit; 2-1-3. Motor unit; 2-1-4. Stroke control unit;

[0037] 2-1-4-1 Open the limit switch assembly; 2-1-4-1-1 Open the limit switch; 2-1-4-1-2 Open the limit switch baffle; 2-1-4-2 Close the limit switch assembly; 2-1-4-2-1 Close the limit switch; 2-1-4-2-2 Close the limit switch baffle;

[0038] 2-1-5 Lower connector for collector; 2-1-6 Collector flow channel; 2-1-7 Collector flow hole; 2-1-8 Upper connector for collector; 2-1-9 Collector rubber sleeve; 2-1-10 Coupling; 2-1-11 Lead screw assembly; 2-1-12 Leaf spring assembly; 2-1-13 Spring assembly; 2-1-14 Outer protective tube for collector;

[0039] 2-2 Measurement subsection; 2-2-1 Measurement main control unit; 2-2-1-1 Microcontroller and peripheral circuits; 2-2-1-2 Magnetic positioning circuit;

[0040] 2-2-2 Downhole signal acquisition unit; 2-2-2-1 Temperature measurement circuit; 2-2-2-2 Pressure measurement circuit; 2-2-2-3 Turbine signal measurement circuit; 2-2-2-4 ADC acquisition circuit;

[0041] 2-2-3 Measurement of power supply unit; 2-2-4 Measurement of communication unit; 2-2-4-1 Measurement of code transmission circuit; 2-2-4-2 Measurement of decoding circuit;

[0042] 2-2-5 Turbine signal measurement unit; 2-2-5-1 Turbine blade assembly; 2-2-5-2 Support assembly; 2-2-5-2-1 Front support member; 2-2-5-2-2 Rear support member; 2-2-5-3 Detection assembly; 2-2-5-3-1 First magnet; 2-2-5-3-2 Hall sensor;

[0043] 2-2-6 Pressure and temperature measurement unit; 2-2-6-1 First temperature sensor; 2-2-6-2 Second temperature sensor; 2-2-6-3 Pressure sensor assembly; 2-2-6-3-1 Pressure sensor; 2-2-6-3-2 Pressure tap plug;

[0044] 2-2-7 Magnetic positioning measurement unit; 2-2-7-1 Second magnet; 2-2-7-2 Coil; 2-2-7-3 Coil support mechanism;

[0045] 2-2-8 Measuring connector; 2-2-8-1 Sliding socket; 2-2-8-2 Sealing ring;

[0046] 2-2-9 Measure the flow channel; 2-2-10 Measure the outlet orifice; 2-2-11 Measure the flow divider; 2-2-12 Measure the outer protective tube; 2-2-13 Measure the lower connector;

[0047] 2-3 cable heads;

[0048] 3 DC carrier bus; 4 Electric winch; 5 Tubing; 6 Host computer; 7 Injector; 8 Wellhead blowout preventer; 9 Tubing coupling; Detailed Implementation

[0049] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so as to better understand the purpose, features and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are only for illustrating the essential spirit of the technical solution of the present invention.

[0050] like Figure 1 As shown. This invention provides a downhole multi-parameter online acquisition system for CO2 injection wells, including a surface controller 1 and a downhole measuring instrument 2. The surface controller 1 is sequentially connected to an injector 7 and the downhole measuring instrument 2 via a DC carrier bus 3. An electric winch 4 lowers the injector 7 and the downhole measuring instrument 2 into the tubing 5 through the wellhead blowout preventer 8 at the upper end of the tubing 5. The surface controller 1 supplies power to the downhole measuring instrument 2 via the DC carrier bus 3, and the two communicate via bidirectional DC carrier communication.

[0051] The ground controller 1 monitors and controls the CO2 parameter data collected by the downhole measuring instrument 2 in real time via DC carrier communication through the DC carrier bus 3. At the same time, it forwards the CO2 parameter data to the host computer 6, where it is displayed, processed and stored on the software of the host computer 6. The host computer 6 calculates the CO2 injection amount of the oil layer where the downhole measuring instrument 2 is located based on the CO2 parameter data.

[0052] The DC carrier bus 3 is preferably a corrosion-resistant armored cable.

[0053] Specifically, the ground controller 1 is installed on the field logging vehicle and can be wired to the local monitoring host computer 6. The ground controller 1 performs current collection control on the downhole measuring instrument 2 to monitor parameters such as CO2 temperature, pressure, and flow rate at the oil layer where the downhole measuring instrument 2 is located. During current collection control, the host computer 6 communicates with the ground controller 1 to control the current collection, preset, and store downhole cable parameters of the downhole measuring instrument 2. At the same time, the ground controller 1 can automatically adjust the voltage to supply power to the downhole measuring instrument 2.

[0054] like Figure 2As shown. The ground controller 1 includes a ground power supply unit 1-1, a ground main control unit 1-2, a ground programmable control unit 1-3, a ground switching unit 1-4, a carrier communication unit 1-5, a ground acquisition unit 1-6, a polarity switching switch 1-7, a ground communication unit 1-8, and a ground output unit 1-9. The ground main control unit 1-2 controls the carrier communication unit 1-5 to communicate with the downhole measuring instrument 2 via a DC carrier bus 3; the ground main control unit 1-2 outputs control signals to the ground programmable control unit 1-3, which in turn controls the ground programmable control unit 1-3 to output current loop control signals to the ground power supply unit 1-1, which in turn controls the ground power supply unit 1-1 to output adjustable voltage power to supply power to the downhole measuring instrument 2; the ground main control unit 1-2 also communicates with the host computer 6, receives instructions from the host computer 6, processes them, and responds to commands.

[0055] Specifically, the ground main control unit 1-2 is connected to the ground acquisition unit 1-6 through the GPIO interface (general purpose I / O interface) and performs ADC (analog-to-digital conversion) processing and judgment on the voltage and current signals of the adjustable power supply acquired by the ground acquisition unit 1-6. When the ground main control unit 1-2 detects overcurrent or voltage abnormality, it controls the ground output unit 1-9 to stop outputting the adjustable voltage. The ground main control unit 1-2 is connected to the ground programmable control unit 1-3 via GPIO to achieve adjustable power supply control; the ground main control unit 1-2 is connected to the carrier communication unit 1-5 via the serial UART (Universal Asynchronous Receiver / Transmitter) interface to achieve communication with the downhole measuring instrument 2; the ground main control unit 1-2 is connected to the ground output unit 1-9 via the GPIO interface to control the adjustable power supply output, and the downhole measuring instrument 2 is powered by the ground output unit 1-9; the ground main control unit 1-2 is connected to the ground communication unit 1-8 via USB (Universal Serial Bus), and the ground communication unit 1-8 is connected to the host computer 6 to achieve communication between the ground main control unit 1-2 and the host computer 6.

[0056] The ground power supply unit 1-1 is connected to a 220V AC power supply and outputs 5V, ±12V, and ±24V DC power to power other units of the ground controller 1. The ground power supply unit 1-1 also outputs a 0-300V adjustable DC power supply to power the downhole measuring instrument 2. The magnitude of the adjustable DC power input to the ground power supply unit 1-1 is controlled by the ground programmable control unit 1-3. The ground switching unit 1-4 and polarity switching switch 1-7 control the polarity of the adjustable DC power supply, and the output of the adjustable DC power supply is controlled by the ground output unit 1-9. The ground switching unit 1-4 controls the adjustable DC power supply output from the ground power supply unit 1-1 to switch polarity or not based on the polarity switching switch 1-7 and the ground programmable control unit 1-3. When the polarity is switched for current collection control, a negative polarity adjustable power supply is output.

[0057] The carrier communication unit 1-5 enables communication between the ground controller 1 and the downhole measuring instrument 2. The carrier communication unit 1-5 includes a carrier coding circuit and a carrier decoding circuit. The carrier coding circuit outputs a normalized Mann code signal to the ground output unit 1-9 based on the coded control signal from the ground main control unit 1-2. The ground output unit 1-9 loads the normalized Mann code signal onto the DC carrier bus 3 and transmits it to the downhole measuring instrument 2.

[0058] The carrier decoding circuit amplifies and converts the polarized Man code signal received by the DC carrier bus 3 and uploaded to the downhole measuring instrument 2 by the ground output unit 1-9 according to the decoding gain set by the ground main control unit 1-2, and then outputs it to the ground main control unit 1-2 for parsing processing.

[0059] The ground output unit 1-9 serves as the controllable output terminal of the DC adjustable power supply, and is controlled by the ground main control unit 1-2 issuing control signals.

[0060] Furthermore, the ground main control unit 1-2 is equipped with a microcontroller, specifically a DSPIC30F6010-20E microcontroller. The microcontroller in the ground main control unit 1-2 runs an embedded program, outputting control signals to control the ground programmable control unit 1-3 to output a 4-20mA current loop control signal. This current loop signal then controls the ground power supply unit 1-1 to output a DC adjustable power supply to power the downhole measuring instrument 2. Simultaneously, the ground programmable control unit 1-3 controls the output circuit of the ground switching unit 1-4.

[0061] The ground main control unit 1-2 runs an embedded program on its microcontroller to perform reduced-biased Man code encoding and control decoding, and interacts with the carrier communication unit 1-5 to achieve communication with the downhole measuring instrument 2.

[0062] The microcontroller of the ground main control unit 1-2 runs an embedded program to perform ADC processing and judgment on the voltage and current signals of the DC adjustable power supply collected by the ground acquisition unit 1-6. When the microcontroller of the ground main control unit 1-2 detects overcurrent or voltage abnormality, it controls the ground output unit 1-9 to stop outputting the adjustable voltage. The microcontroller of the ground main control unit 1-2 runs an embedded program to communicate with the host computer 6 and receives instructions from the host computer 6 for processing and replying to commands.

[0063] like Figures 3-5 As shown. The downhole measuring instrument 2 includes a flow collecting sub 2-1 and a measuring sub 2-2. The lower end of the flow collecting sub 2-1 and the upper end of the measuring sub 2-2 are both provided with mating threads. The flow collecting sub 2-1 and the measuring sub 2-2 are connected by mating threads. The upper end of the flow collecting sub 2-1 is threaded with a cable head 2-3.

[0064] The current collecting section 2-1 includes a current collecting upper connector 2-1-8, the lower end of which is threadedly connected to a current collecting outer protective tube 2-1-14. Inside the current collecting outer protective tube 2-1-14, from top to bottom, are arranged an opening control unit 2-1-1, a closing control unit 2-1-2, a motor unit 2-1-3, a coupling 2-1-10, and a lead screw assembly 2-1-11. The motor unit 2-1-3 is connected to the lead screw assembly 2-1-11 via the coupling 2-1-10. A stroke control unit 2-1-4 is installed on the lead screw assembly 2-1-11. The opening control unit 2-1-1 and the closing control unit 2-1-2 are electrically connected to the motor unit 2-1-3 to control the forward and reverse rotation of the motor unit 2-1-3. The current collector outer protective tube 2-1-14 serves as a protective tube to protect the opening control unit 2-1-1, the closing control unit 2-1-2, the motor unit 2-1-3, and the stroke control unit 2-1-4.

[0065] The lower end of the lead screw assembly 2-1-11 extending from the outer protective tube 2-1-14 is connected to a leaf spring assembly 2-1-12. The upper end of the leaf spring assembly 2-1-12 is connected to a spring assembly 2-1-13 sleeved on the lower end of the lead screw assembly 2-1-11. A collector rubber sleeve 2-1-9 is sleeved on the outer periphery of the leaf spring assembly 2-1-12. A collector lower connector 2-1-5 is provided at the lower end of the leaf spring assembly 2-1-12.

[0066] The lower end of the outer protective tube 2-1-14 is provided with a current collection passage 2-1-6. The current collection passage 2-1-6 passes through the center of the spring assembly 2-1-13 and the leaf spring assembly 2-1-12 and is threadedly connected to the lower connector 2-1-5.

[0067] The flow collection channel 2-1-6 has several flow collection holes 2-1-7 arranged radially on the outer periphery of a portion of the channel passing through the spring assembly 2-1-13. The flow collection holes 2-1-7 are in communication with the inner cavity of the flow collection channel 2-1-6.

[0068] The motor unit 2-1-3, coupling 2-1-10, lead screw assembly 2-1-11, leaf spring assembly 2-1-12, and spring assembly 2-1-13 form a linkage mechanism. The rotational motion of the motor unit 2-1-3 drives the lead screw assembly 2-1-11 to rotate through the coupling 2-1-10. The lead screw assembly 2-1-11 converts the rotational motion into linear motion, which in turn drives the leaf spring assembly 2-1-12 to move linearly. The spring assembly 2-1-13 provides buffering for the leaf spring assembly 2-1-12 as it moves. Due to the restriction of the current collector lower connector 2-1-5, the inner spokes of the leaf spring assembly 2-1-12 are deformed and bent or straightened by the external force of linear movement, which in turn drives the current collector rubber sleeve 2-1-9 fitted on the leaf spring assembly 2-1-12 to open or retract.

[0069] After the flow collector sleeve 2-1-9 is opened, the downhole measuring instrument 2 is set in the injection well tubing 5. CO2 enters the flow collector passage 2-1-6 through the flow collector hole 2-1-7, and then enters the measuring sub 2-2 after passing through the flow collector connector 2-1-5.

[0070] The current collector lower connector 2-1-5 and the measurement upper connector 2-2-8 are tightened together by threaded connection. At the same time, the power interface of the current collector lower connector 2-1-5 is connected to the sliding socket 2-2-8-1 of the measurement upper connector 2-2-8 to realize the electrical connection of the bus.

[0071] Furthermore, the stroke control unit 2-1-4 includes an open stroke switch assembly 2-1-4-1 and a close stroke switch assembly 2-1-4-2. The open stroke switch assembly 2-1-4-1 is used to control the forward stroke of the lead screw assembly 2-1-11, that is, the opening size of the manifold 2-1-9, to prevent the manifold 2-1-9 from opening too large or too small.

[0072] The open limit switch assembly 2-1-4-1 consists of an open limit switch 2-1-4-1-1 and an open limit switch baffle 2-1-4-1-2. The open limit switch baffle 2-1-4-1-2 is installed on one side of the lead screw assembly 2-1-11 and moves with the movement of the lead screw assembly 2-1-11. The open limit switch 2-1-4-1-1 is installed on the outside of the sleeve of the lead screw assembly 2-1-11 at the open stroke position. The close limit switch assembly 2-1-4-2 consists of a close limit switch 2-1-4-2-1 and a close limit switch baffle 2-1-4-2-2. The close limit switch baffle 2-1-4-2-2 is installed on the other side of the lead screw assembly 2-1-11 and moves with the movement of the lead screw assembly 2-1-11. The close limit switch 2-1-4-2-1 is installed on the outside of the sleeve of the lead screw assembly 2-1-11 at the close stroke position. The opening or retraction of the manifold 2-1-9 is controlled by opening the limit switch assembly 2-1-4-1 and closing the limit switch assembly 2-1-4-2 to control the stroke of the lead screw assembly 2-1-11.

[0073] Furthermore, the normally closed contact of the open limit switch 2-1-4-1-1 is connected in series with the control circuit of the open control unit 2-1-1, and the normally closed contact of the close limit switch 2-1-4-2-1 is connected in series with the control circuit of the close control unit 2-1-2. When the control circuit of the open control unit 2-1-1 controls the opening action, the open limit switch baffle 2-1-4-1-2 moves with the forward stroke of the lead screw assembly 2-1-11. When it reaches the position of the open limit switch 2-1-4-1-1, the open limit switch baffle 2-1-4-1-2 triggers the micro-motion contact of the open limit switch 2-1-4-1-1, causing the normally closed contact of the open limit switch 2-1-4-1-1 to open, the output of the control circuit of the open control unit 2-1-1 to disconnect, and the motor unit 2-1-3 to stop.

[0074] When the control unit 2-1-2 controls the closing action, the limit switch baffle 2-1-4-2-2 moves with the retracting stroke of the lead screw assembly 2-1-11. When it reaches the position of the limit switch 2-1-4-2-1, the limit switch baffle 2-1-4-2-2 triggers the micro-motion contact of the limit switch 2-1-4-2-1, causing the normally closed contact of the limit switch 2-1-4-2-1 to open. This disconnects the control circuit output of the control unit 2-1-2, and the motor unit 2-1-3 stops. The positions of the limit switches 2-1-4-1-1 and 2-1-4-2-1 are adjusted according to the required opening size of the manifold 2-1-9 to adjust the stroke of the lead screw assembly 2-1-11.

[0075] Furthermore, the power interface of the cable head 2-3 is electrically connected to the power interface of the open control unit 2-1-1 through the power interface of the upper current collector 2-1-8. The power interface of the open control unit 2-1-1 is also electrically connected to the power interface of the lower current collector 2-1-5. The controllable power interface of the ground controller 1 is electrically connected to the power interface of the cable head 2-3 through the DC carrier bus 3 to form the power path of the current collector section.

[0076] Furthermore, both the opening control unit 2-1-1 and the closing control unit 2-1-2 are control circuit boards, both mounted on opposite sides of the circuit board frame. The motor unit 2-1-3 is mounted at the rear end of the circuit board frame, and the stroke control unit 2-1-4 is mounted on the outer frame located at the position of the lead screw assembly 2-1-11. Both the circuit board frame and the outer frame are housed within the current collector outer sleeve 2-1-14 between the motor unit 2-1-3 and the current collector upper connector 2-1-8.

[0077] Furthermore, the opening control unit 2-1-1 and the closing control unit 2-1-2 are controlled by the ground controller 1 outputting negative power of different amplitudes. By switching the power output polarity switching switch 1-7 of the ground controller 1 to negative, the ground programmable unit 1-3 of the ground controller 1 controls the output of negative power to the DC carrier bus 3, and the measurement section 2-2 does not operate.

[0078] When the host computer 6 controls the current collector tube 2-1-9 to open, it sends an opening command to the ground controller 1. The microcontroller of the ground main control unit 1-2 of the ground controller controls the ground programmable control unit 1-3 to output negative power to the DC carrier bus 3. The power supply voltage transmitted to the current collector stub 2-1 through the DC carrier bus 3 is -36V. Because the negative power supply voltage is effective, the opening control unit 2-1-1 drives the output positive power, controlling the motor unit 2-1-3 to rotate forward, driving the coupling 2-1-10 to rotate in the same direction. The coupling 2-1-10 drives the lead screw assembly 2-1-11 forward, pushing the leaf spring assembly 2-1-12 to open, and simultaneously driving the spring assembly 2-1-13 to stretch, so that the current collector tube 2-1-9 opens to achieve the current collection state. The closing control unit 2-1-2 has no output at this time.

[0079] When the host computer 6 controls the retraction of the current collector tube 2-1-9, it sends a retraction command to the ground controller 1. The microcontroller of the ground main control unit 1-2 of the ground controller controls the ground programmable control unit 1-3 to output negative power to the DC carrier bus 3. The power voltage output to the current collector stub 2-1 through the DC carrier bus 3 is -72V. Because the negative power voltage is valid, the closing control unit 2-1-2 drives the output of negative power, controlling the motor unit 2-1-3 to reverse and drive the coupling 2-1-10 to rotate in the same direction. The coupling 2-1-10 drives the lead screw assembly 2-1-11 to retract, pulling the leaf spring assembly 2-1-12 back. The restoring force of the spring assembly 2-1-13 pulls the leaf spring assembly 2-1-12, causing the outer diameter of the current collector tube 2-1-9 to retract and return to its original position, reaching a non-current collector state. The opening control unit 2-1-1 has no output at this time.

[0080] like Figure 6 As shown. The measuring section 2-2 includes a measuring upper connector 2-2-8, a measuring flow channel 2-2-9 at the lower end of the measuring upper connector 2-2-8, a measuring outlet hole 2-2-10 radially arranged on the outer periphery of the lower end of the measuring flow channel 2-2-9, a measuring outer protective tube 2-2-12 connected to the lower end of the measuring flow channel 2-2-9, a threaded connection between the upper end of the measuring upper connector 2-2-8 and the lower collecting connector 2-1-5, and a communication between the upper end of the measuring flow channel 2-2-9 and the collecting flow channel 2-1-6. The measuring flow channel 2-2-9 and the collecting flow channel 2-1-6 form the internal flow channel of the downhole measuring instrument 2.

[0081] The measuring flow channel 2-2-9 is internally equipped with a series-connected flow divider 2-2-11 and a turbine signal measuring unit 2-2-5. In the flow collection state, CO2 enters the measuring flow channel 2-2-9 from the flow collection channel 2-1-6, passes through the flow divider 2-2-11 and the turbine signal measuring unit 2-2-5, and then flows out from the measuring outlet orifice 2-2-10.

[0082] The upper part of the measuring outer protective tube 2-2-12 is fitted with a pressure and temperature measuring unit 2-2-6, and the lower part of the measuring outer protective tube 2-2-12 is fitted with a magnetic positioning measuring unit 2-2-7. A circuit board frame is provided between the pressure and temperature measuring unit 2-2-6 and the magnetic positioning measuring unit 2-2-7. The circuit board frame is equipped with a measuring main control unit 2-2-1, a downhole signal acquisition unit 2-2-2, a measuring power supply unit 2-2-3, and a measuring communication unit 2-2-4. The lower end of the measuring outer protective tube 2-2-12 is threadedly connected to a measuring lower connector 2-2-13. The measuring outer protective tube 2-2-12 protects the measuring main control unit 2-2-1, the downhole signal acquisition unit 2-2-2, the measuring power supply unit 2-2-3, the measuring communication unit 2-2-4, and the magnetic positioning measuring unit 2-2-7 located inside it.

[0083] Furthermore, the measuring section 2-2 is used to measure parameters such as the flow rate, temperature, and pressure of CO2 in the injection well tubing. When the injection well tubing 5 reaches the flow collection state, CO2 passes through the turbine signal measuring unit 2-2-5, which measures the turbine flow rate signal and transmits it to the downhole signal acquisition unit 2-2-2 for processing. After CO2 passes through the turbine signal measuring unit 2-2-5 and then through the measuring outlet orifice 2-2-10, the pressure and temperature measuring unit 2-2-6 at the lower end of the measuring outlet orifice 2-2-10 measures the pressure and temperature signals of CO2 and transmits them to the downhole signal acquisition unit 2-2-2 for processing.

[0084] The downhole signal acquisition unit 2-2-2 adjusts the acquired CO2 turbine flow, pressure, and temperature signals and then sends them to the measurement control unit 2-2-1 for signal processing and conversion. The acquired CO2 parameter data are then uploaded to the ground controller 1 via the DC carrier bus 3 through the measurement communication unit 2-2-4 using DC carrier communication.

[0085] The magnetic positioning measurement unit 2-2-7 collects the parameter data signals of the magnetic field change of the tubing 5 in real time and sends them to the measurement main control unit 2-2-1 for signal processing and conversion. Then, the collected magnetic field change parameter data is uploaded to the ground controller 1 via the DC carrier bus 3 through the measurement communication unit 2-2-4 in the DC carrier communication mode. The ground controller 1 determines the position of the tubing joint 9 and estimates the depth of the downhole measuring instrument 2.

[0086] The measurement power supply unit 2-2-3 is connected to the measurement main control unit 2-2-1 to provide various power supplies for the measurement section 2-2.

[0087] Specifically, the measurement control unit 2-2-1 is the core unit for control and signal processing of the downhole measurement instrument 2. It communicates with the surface controller 1. The measurement control unit 2-2-1 simultaneously processes the input signals from the downhole signal acquisition unit 2-2-2, the turbine signal measurement unit 2-2-5, and the magnetic positioning measurement unit 2-2-7, converts them, and then uploads them to the surface controller 1 via the measurement communication unit 2-2-4. The measurement power supply unit 2-2-3 mainly converts the power supplied from the surface controller 1 to the downhole measurement instrument 2 via the DC carrier bus 3 into +15V, -15V, and 5V to provide the necessary power for the measurement control unit 2-2-1, the measurement communication unit 2-2-4, and the downhole signal acquisition unit 2-2-2. The measurement power supply unit 2-2-3 is an integrated switching power supply module.

[0088] The measurement main control unit 2-2-1 is a control circuit with a microcontroller chip. It includes a microcontroller and peripheral circuits 2-2-1-1 and a magnetic positioning circuit 2-2-1-2. The measurement communication unit 2-2-4 includes a measurement code transmission circuit 2-2-4-1 and a measurement decoding circuit 2-2-4-2. These circuits communicate with the ground controller 1 to generate and decode returned-polarized Mann code. The downhole signal acquisition unit 2-2-2 includes a temperature measurement circuit 2-2-2-1, a pressure measurement circuit 2-2-2-2, a turbine signal measurement circuit 2-2-2-3, and an ADC acquisition circuit 2-2-2-4.

[0089] The microcontroller and peripheral circuit 2-2-1-1 serve as the core control circuit for the downhole measuring instrument 2. The microcontroller used in the main control unit 2-2-1 is a DSPIC30F6010-20E. The GPIO interface pins of the microcontroller in the main control unit 2-2-1 are electrically connected to the measurement code transmission circuit 2-2-4-1. The measurement code transmission circuit 2-2-4-1 outputs a reduced-polarization Mann code waveform, which is loaded onto the DC carrier bus 3 and uploaded to the ground controller 1 to achieve uplink communication between the downhole measuring instrument 2 and the ground controller 1.

[0090] The UART (Universal Asynchronous Serial Interface) pin of the microcontroller in the measurement main control unit 2-2-1 is electrically connected to the measurement decoding circuit 2-2-4-2. The ground controller 1 sends the returned-biased Man code sequence waveform to the downhole measurement instrument 2 via the DC carrier bus 3. After being converted and processed into a TTL level serial port signal by the measurement decoding circuit 2-2-4-2, it is input to the UART pin to realize downlink communication between the ground controller 1 and the downhole measurement instrument 2.

[0091] The microcontroller of the measurement main control unit 2-2-1 is connected to the magnetic positioning circuit 2-2-1-2 through the GPIO interface pin to detect and process the output signal of the magnetic positioning circuit 2-2-1-2.

[0092] The microcontroller of the measurement main control unit 2-2-1 communicates with the downhole signal acquisition unit 2-2-2 via an SPI (Serial Peripheral Interface) pin to acquire the temperature and pressure parameter data collected and converted by the downhole signal acquisition unit 2-2-2; the microcontroller of the measurement main control unit 2-2-1 is electrically connected to the turbine signal measurement circuit 2-2-2-3 via a GPIO pin to detect and process the output signal of the turbine signal measurement circuit 2-2-2-3.

[0093] Furthermore, the microcontroller of the measurement main control unit 2-2-1 runs an embedded program, which, through the encoding of the returned partial Man code sequence and the control of the measurement code transmission circuit 2-2-4-1, communicates with the ground controller 1 to realize the uploading of parameters such as CO2 temperature, pressure, turbine signal frequency, and magnetic positioning signal, as well as the reply of various commands; at the same time, it receives the instructions sent by the ground controller 1 converted by the measurement decoding circuit 2-2-4-2, and performs error checking and communication protocol parsing before processing and replying to commands accordingly.

[0094] The microcontroller of the main control unit 2-2-1 runs an embedded program and periodically communicates with the downhole signal acquisition unit 2-2-2 to acquire CO2 temperature, pressure data, turbine signals and magnetic positioning signals.

[0095] Specifically, the measurement code transmission circuit 2-2-4-1 converts the normalized Mann code signal output by the microcontroller of the measurement main control unit 2-2-1 into a normalized Mann code waveform through a driving circuit and outputs it to the DC carrier bus 3; the measurement decoding circuit 2-2-4-2 converts the normalized Mann code waveform sent by the ground controller 1 into a TTL level serial port signal through an amplification circuit, a filtering circuit, and a conversion circuit and inputs it to the UAR pin of the microcontroller of the measurement main control unit 2-2-1.

[0096] The magnetic positioning circuit 2-2-1-2 amplifies the electromagnetic induction signal of the magnetic positioning measurement unit 2-2-7, converts it into a square wave signal, and then inputs it to the GPIO pin of the microcontroller for detection and processing.

[0097] The temperature measurement circuit 2-2-2-1 amplifies the signals from the first temperature sensor 2-2-6-1 and the second temperature sensor 2-2-6-2 of the pressure and temperature measurement unit 2-2-6 and inputs them to the ADC acquisition circuit 2-2-2-4 for digital-to-analog conversion.

[0098] The pressure measurement circuit 2-2-2-2 outputs an excitation signal to the pressure sensor 2-2-6-3-1, and amplifies the output signal of the pressure sensor assembly 2-2-6-3 before inputting it to the ADC acquisition circuit 2-2-2-4 for digital-to-analog conversion.

[0099] The turbine signal measurement circuit 2-2-2-3 filters the signal from the detection component 2-2-5-3 and inputs it to the GPIO pin of the microcontroller for detection processing.

[0100] The ADC acquisition circuit 2-2-2-4 converts the temperature analog signal from the temperature measurement circuit 2-2-2-1 and the pressure analog signal from the pressure measurement circuit 2-2-2-2 into digital signals. Then, it communicates with the measurement master control unit 2-2-1 microcontroller through the SPI interface pin and sends the converted temperature and pressure digital signals to the measurement master control unit 2-2-1 microcontroller for processing.

[0101] Furthermore, since the measuring overcurrent channel 2-2-9 and the sliding socket 2-2-8-1 coexist in the inner cavity of the measuring upper connector 2-2-8, an acid-resistant O-ring 2-2-8-2 is used to seal between the outer periphery of the measuring overcurrent channel 2-2-9 and the sliding socket 2-2-8-1 to prevent CO2 leakage.

[0102] like Figure 7 As shown. The turbine signal measurement unit 2-2-5 includes a turbine blade assembly 2-2-5-1, a support assembly 2-2-5-2, and a detection assembly 2-2-5-3. The turbine signal measurement unit 2-2-5 is disposed in the measurement flow channel 2-2-9 for detecting CO2 flow rate.

[0103] The support assembly 2-2-5-2 is composed of a front support member 2-2-5-2-1 and a rear support member 2-2-5-2-2. The turbine blade assembly 2-2-5-1 is positioned between the front support member 2-2-5-2-1 and the rear support member 2-2-5-2-2, which are supported vertically by the front support member 2-2-5-2-1 and the rear support member 2-2-5-2-2.

[0104] The front support member 2-2-5-2-1 is detachable, and the turbine blade assembly 2-2-5-1 can be installed after detachment. The tightness of the turbine blade assembly 2-2-5-1 can be adjusted by the front support member 2-2-5-2-1. The front support member 2-2-5-2-1 and the rear support member 2-2-5-2-2 support the turbine blade assembly 2-2-5-1 to rotate within the measuring flow channel 2-2-9.

[0105] The detection component 2-2-5-3 includes a first magnet 2-2-5-3-1 and a Hall sensor 2-2-5-3-2. The first magnet 2-2-5-3-1 is embedded in the central shaft of the turbine fan blade assembly 2-2-5-1, and the Hall sensor 2-2-5-3-2 is installed on the inner wall of the measuring flow channel 2-2-9 and is flush with the radial outer circumferential surface of the first magnet 2-2-5-3-1.

[0106] When CO2 flows, the first magnet 2-2-5-3-1 rotates with the turbine blade assembly 2-2-5-1. When the Hall sensor 2-2-5-3-2, which measures the inner wall of the flow channel 2-2-9, passes through it, the movement of the first magnet 2-2-5-3-1 causes a change in the magnetic field induced by the Hall sensor 2-2-5-3-2. Due to the Hall effect, the Hall sensor 2-2-5-3-2 outputs a signal with a change in amplitude, which is then input to the turbine signal measurement circuit 2-2-2-3 for measurement. Since the CO2 flows within the flow channel 2-2-9, driving the turbine blade assembly 2-2-5-1 to rotate, the CO2 flow velocity is proportional to the turbine rotation speed. Furthermore, the change in the amplitude of the signal from the Hall sensor 2-2-5-3-2 is also proportional to the rotation speed. Therefore, the CO2 flow velocity can be calculated by detecting the change in the signal from the Hall sensor 2-2-5-3-2.

[0107] Furthermore, the support assembly 2-2-5-2 includes a pair of bearings, an upper shaft pin, and a lower shaft pin. The upper and lower shaft pins are respectively fixed to the measuring flow channel 2-2-9 by the bearings, and the upper and lower shaft pins support the turbine blade assembly 2-2-5-1 to rotate within the measuring flow channel 2-2-9. The blades of the turbine blade assembly 2-2-5-1 are preferably 6-head spiral blades.

[0108] Furthermore, after CO2 flows out from the turbine signal measurement unit 2-2-5 and then through the measuring outlet orifice 2-2-10, it needs to pass through the pressure and temperature measurement unit 2-2-6, which measures the temperature and pressure of the CO2 injected into the well.

[0109] The pressure and temperature measuring unit 2-2-6 includes a temperature sensor assembly and a pressure sensor assembly 2-2-6-3. The pressure sensor assembly 2-2-6-3 consists of a pressure tap plug 2-2-6-3-2 and a pressure sensor 2-2-6-3-1. The pressure tap plug 2-2-6-3-2 is sleeved on the upper end of the measuring outer protective tube 2-2-12, 10mm away from the lower end of the measuring outlet orifice 2-2-10. The pressure sensor 2-2-6-3-1 is installed on the pressure tap plug 2-2-6-3-2, and measures the pressure of CO2 after taking pressure through the pressure tap plug 2-2-6-3-2.

[0110] The pressure tap plug 2-2-6-3-2 is a threaded plug with a gap in the middle. The pressure tap plug 2-2-6-3-2 is threadedly connected to the measuring outer protective tube 2-2-12. The gap of the pressure tap plug is connected to the interior of the measuring outer protective tube 2-2-12. An L-shaped pressure tapping channel is provided on the gap in the middle of the pressure tap plug to connect to the pressure sensor 2-2-6-3-1. The pressure sensor 2-2-6-3-1 is radially arranged on the pressure tap plug and communicates with the L-shaped pressure tapping channel.

[0111] When the pressure sensor 2-2-6-3-1 measures pressure, it obtains an excitation signal from the pressure measurement circuit 2-2-2-2 and simultaneously transmits the pressure detection signal to the pressure measurement circuit 2-2-2-2.

[0112] The temperature sensor assembly consists of a first temperature sensor 2-2-6-1 and a second temperature sensor 2-2-6-2; the first temperature sensor 2-2-6-1 is installed on the outside of the measuring outlet orifice 2-2-10 and is used to detect the CO2 temperature. The first temperature sensor 2-2-6-1 is preferably a PT1000 platinum resistance sensor.

[0113] The second temperature sensor 2-2-6-2 is installed in the cavity at the installation position of the pressure sensor 2-2-6-3-1 for pressure-temperature compensation. The first temperature sensor 2-2-6-1 and the second temperature sensor 2-2-6-2 transmit the temperature detection signal to the temperature measurement circuit 2-2-2-1.

[0114] Furthermore, the magnetic positioning measurement unit 2-2-7 includes a second magnet 2-2-7-1, a coil 2-2-7-2, and a coil support mechanism 2-2-7-3. The second magnet 2-2-7-1 is used to enhance the magnetic field induction signal. The coil 2-2-7-2 is provided with second magnets 2-2-7-1 at both ends. The coil support mechanism 2-2-7-3 is threadedly connected inside the measuring outer protective tube 2-2-12 to support the pair of magnets and the coil 2-2-7-2 at the upper end. The coil support mechanism 2-2-7-3 provides support and protection for the second magnets 2-2-7-1 and the coil 2-2-7-2.

[0115] Furthermore, the coil support mechanism 2-2-7-3 consists of a compression spring and a limiting screw ring. The limiting screw ring is threadedly connected to the measuring outer protective tube 2-2-12, and the compression spring is sleeved inside the limiting screw ring to support the second magnet 2-2-7-1 and the coil 2-2-7-2.

[0116] When the position of the tubing joint 9 is determined by the magnetic positioning measurement unit 2-2-7, when the magnetic positioning measurement unit 2-2-7 passes the tubing joint 9 on the tubing 5, the magnetic conductivity of the tubing joint 9 changes significantly, causing the induced magnetic field of the coil 2-2-7-2 to change. The electromagnetic induction effect generates a large change in the electrical signal, which is input to the magnetic positioning circuit 2-2-1-2 to detect the position of the tubing joint 9. Then, the downhole measuring instrument 2 is lifted and placed at the position of the upper injector 7 of the tubing joint 9 in the oil layer.

[0117] like Figure 8 As shown. This invention also provides a method for online acquisition of multiple downhole parameters in CO2 injection wells, implemented through the online acquisition system of this invention, which includes the following steps:

[0118] Step S1: Place the downhole measuring instrument 2 at the upper part of the injection device 7 of the tubing joint 9;

[0119] Specifically, the ground controller 1 is first connected to the host computer 6, and then the ground output unit 1-9 of the ground controller 1 and the cable head 2-3 of the downhole measuring instrument 2 are connected through the DC carrier bus 3. Then, the downhole measuring instrument 2 is lowered into the CO2 injection well by the electric winch 4 through the wellhead blowout prevention system 8.

[0120] During the lowering process, the cable of the electric winch 4 is lowered to the depth of the injection well to be tested. The depth and formation of the downhole measuring instrument 2 are determined by the magnetic positioning pulse waveform. Then, the downhole measuring instrument 2 is lifted and placed at the upper part of the injection device 7 of the tubing joint 9.

[0121] In step S2, the host computer 6 sends a command to the ground controller 1 to open the rubber tube. The ground controller 1 controls the downhole measuring instrument 2 to open the flow collecting rubber tube 2-1-9 and set the oil pipe 5. The CO2 in the oil pipe 5 passes through the internal flow channel of the downhole measuring instrument 2.

[0122] Specifically, first, the power output polarity switch 1-7 of the ground controller 1 is switched to negative. Then, the upper computer 6 operates the rubber tube opening button to send a rubber tube opening command to the ground controller 1. The ground controller 1 controls the flow collecting rubber tube 2-1-9 of the downhole measuring instrument 2 to open, so that the downhole measuring instrument 2 sets the tubing 5. CO2 in the tubing 5 passes through the flow collecting channel 2-1-6 and the measurement channel 2-2-9 of the downhole measuring instrument 2 in sequence. Then, the power output polarity switch 1-7 of the ground controller 1 is restored to positive.

[0123] In step S3, the CO2 flow rate is calculated when CO2 passes through the turbine signal measurement unit 2-2-5; the temperature and pressure of CO2 at the injection well location where the downhole measuring instrument 2 is located are measured by the pressure and temperature measurement unit 2-2-6, and the CO2 injection amount of the oil layer is obtained by combining the CO2 flow rate.

[0124] Specifically, when CO2 passes through the turbine signal measurement unit 2-2-5 in the measurement flow channel 2-2-9, the turbine signal measurement unit 2-2-5 uploads the turbine frequency signal to the ground controller 1 through the measurement communication unit 2-2-4, and the ground controller 1 forwards it to the host computer 6.

[0125] When CO2 flows out from the measuring outlet hole 2-2-10 at the lower end of the measuring flow channel 2-2-9, it passes through the pressure and temperature measuring unit 2-2-6. The pressure and temperature measuring unit 2-2-6 collects the temperature and pressure data of CO2 at the location and uploads the temperature and pressure data to the ground controller 1 through the measuring communication unit 2-2-4. The ground controller 1 forwards the data to the host computer 6. The host computer 6 calculates the downhole CO2 density based on the temperature and pressure data, and then calculates the CO2 flow velocity based on the turbine frequency. Finally, it obtains the CO2 injection amount of the oil layer.

[0126] In step S4, the host computer 6 issues a command to close the rubber tube, and the ground controller 1 controls the downhole measuring instrument 2 to retract the collecting rubber tube 2-1-9;

[0127] Specifically, by switching the power output polarity switch 1-7 of the ground controller 1 to the negative direction, and then by operating the rubber tube closing button of the host computer 6 to send a rubber tube closing command to the ground controller 1, the ground controller 1 controls the downhole measuring instrument 2 to retract the collecting rubber tube 2-1-9, and then restores the power output polarity switch 1-7 of the ground controller 1 to the positive direction.

[0128] Step S5: Continue to raise or lower the downhole measuring instrument 2, and measure the CO2 injection volume of each oil layer in sequence according to steps S1-S3 to obtain the CO2 injection volume of the entire injection well; then raise the downhole measuring instrument 2 out of the well again through the electric winch 4.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole multi-parameter online acquisition system for CO2 injection wells, characterized in that: The system includes a ground controller (1) and a downhole measuring instrument (2). The ground controller (1) and the downhole measuring instrument (2) are electrically connected via a DC carrier bus (3). The downhole measuring instrument (2) is lowered into the tubing (5) to measure the CO2 parameter data of the injection well layers in sequence. The ground controller (1) monitors and controls the CO2 parameter data collected by the downhole measuring instrument (2) in real time via the DC carrier bus (3) using DC carrier communication. The ground controller (1) forwards the collected CO2 parameter data to the host computer (6) in real time. The host computer (6) processes the data and obtains the CO2 injection amount of the oil layer where the downhole measuring instrument (2) is located. The downhole measuring instrument (2) includes a flow collection sub (2-1) and a measuring sub (2-2). The measuring sub (2-2) includes a measuring main control unit (2-2-1), a measuring communication unit (2-2-4), a turbine signal measuring unit (2-2-5) for measuring CO2 parameter data, and a measuring outer protective tube (2-2-12). The measuring main control unit (2-2-1) is installed inside the measuring outer protective tube (2-2-12). A magnetic positioning measuring unit (2-2-7) is also installed inside the measuring outer protective tube (2-2-12). The magnetic positioning measuring unit (2-2-7) collects the magnetic field change parameters of the tubing (5) in real time and sends them to the measuring main control unit (2-2-1). The measuring main control unit (2-2-1) uploads the collected magnetic field change parameters to the ground controller (1) via a DC carrier bus (3) through the measuring communication unit (2-2-4) to determine the position of the tubing clamp (9). The turbine signal measurement unit (2-2-5) includes a turbine blade assembly (2-2-5-1), a support assembly (2-2-5-2), and a detection assembly (2-2-5-3). The detection assembly (2-2-5-3) includes a first magnet (2-2-5-3-1) and a Hall sensor (2-2-5-3-2). The first magnet (2-2-5-3-1) is embedded in the central shaft of the turbine blade assembly (2-2-5-1), and the Hall sensor (2-2-5-3-2) is mounted on the inner wall of the measurement flow channel (2-2-9) and is flush with the radial outer circumferential surface of the first magnet (2-2-5-3-1) as it rotates. The current collecting sub-section (2-1) and the measuring sub-section (2-2) are threaded together; the current collecting sub-section (2-1) includes a current collecting outer protective tube (2-1-14), a motor unit (2-1-3) and a lead screw assembly (2-1-11) are arranged inside the current collecting outer protective tube (2-1-14), the lead screw assembly (2-1-11) extends out of the lower end of the current collecting outer protective tube (2-1-14) and is connected to a leaf spring assembly (2-1-12), and a current collecting rubber sleeve (2-1-9) is sleeved on the outer periphery of the leaf spring assembly (2-1-12); the current collecting outer protective tube (2-1-14) The lower end is also provided with a current collection channel (2-1-6), which passes through the center of the leaf spring assembly (2-1-12) and is connected to a current collection lower connector (2-1-5). The outer periphery of the current collection channel (2-1-6) is provided with a plurality of current collection holes (2-1-7). The motor unit (2-1-3) controls the lead screw assembly (2-1-11) to drive the leaf spring assembly (2-1-12) to deform, bend or straighten, thereby causing the current collection rubber sleeve (2-1-9) fitted on the leaf spring assembly (2-1-12) to open or retract. The measuring sub (2-2) further includes a measuring flow channel (2-2-9) and a pressure and temperature measuring unit (2-2-6). The pressure and temperature measuring unit (2-2-6) is located at the lower end of the measuring flow channel (2-2-9). A measuring outlet hole (2-2-10) is located on the outer periphery of the lower end of the measuring flow channel (2-2-9). The turbine signal measuring unit (2-2-5) is located inside the measuring flow channel (2-2-9). The downhole signal acquisition unit (2-2-2) and the measuring communication unit (2-2-4) are also located inside the measuring outer protective tube (2-2-12). The measuring sub (2-2) is located within the flow collector sleeve (2-1-9). After the set-sealing tubing (5) is opened, CO2 enters the collecting flow channel (2-1-6) from the collecting flow passage (2-1-7) and then enters the measuring flow channel (2-2-9). After passing through the turbine signal measuring unit (2-2-5), it flows out from the measuring flow outlet (2-2-10). The turbine signal measuring unit (2-2-5) transmits the measured turbine flow signal to the downhole signal acquisition unit (2-2-2). CO2 flows out from the measuring flow outlet (2-2-10) and passes through the pressure and temperature measuring unit (2-2-6). The pressure and temperature measuring unit (2-2-6) transmits the measured pressure and temperature signals of CO2 to the downhole signal acquisition unit (2-2-2).

2. The downhole multi-parameter online acquisition system for CO2 injection wells according to claim 1, characterized in that: The ground controller (1) includes a ground power supply unit (1-1), a ground main control unit (1-2), a ground programmable control unit (1-3), and a carrier communication unit (1-5). The ground main control unit (1-2) controls the carrier communication unit (1-5) to communicate with the downhole measuring instrument (2) via a DC carrier bus (3). The ground main control unit (1-2) outputs a control signal to control the ground programmable control unit (1-3) to output a current loop control signal to control the ground power supply unit (1-1) to output an adjustable voltage power supply to the downhole measuring instrument (2). The ground main control unit (1-2) also communicates with the host computer (6). The measurement sub (2-2) also includes a downhole signal acquisition unit (2-2-2). After the ground main control unit (1-2) controls the measurement sub (2-2) to collect current, the turbine signal measurement unit (2-2-5) and the pressure and temperature measurement unit (2-2-6) transmit the measured CO2 parameter data to the measurement main control unit (2-2-1) through the downhole signal acquisition unit (2-2-2). The measurement main control unit (2-2-1) then uploads the collected CO2 parameter data to the ground controller (1) via the measurement communication unit (2-2-4) in a DC carrier communication manner.

3. The downhole multi-parameter online acquisition system for CO2 injection wells according to claim 2, characterized in that: The carrier communication unit (1-5) includes a carrier coding circuit and a carrier decoding circuit. The carrier coding circuit outputs a normalized Mann code signal to the ground output unit (1-9) based on the coded control signal from the ground main control unit (1-2). The ground output unit (1-9) loads the normalized Mann code signal onto the DC carrier bus (3) and transmits it to the downhole measuring instrument (2). The carrier decoding circuit amplifies and converts the normalized Mann code signal received by the ground output unit (1-9) according to the decoding gain set by the ground main control unit (1-2) and outputs it to the ground main control unit (1-2) for parsing processing.

4. The downhole multi-parameter online acquisition system for CO2 injection wells according to claim 3, characterized in that: The outer protective tube (2-1-14) for collecting current is also equipped with an opening control unit (2-1-1) and a closing control unit (2-1-2). The opening control unit (2-1-1) and the closing control unit (2-1-2) are electrically connected to the motor unit (2-1-3). The ground main control unit (1-2) controls the ground program control unit (1-3) to output negative power supply voltages of different amplitudes from the ground power supply unit (1-1) to the DC carrier bus (3). The opening control unit (2-1-1) and the closing control unit (2-1-2) receive negative power supply voltages of different amplitudes through the DC carrier bus (3) to control the motor unit (2-1-3) to drive the lead screw assembly (2-1-11) to move forward and backward, so as to control the opening and retraction of the current collector rubber tube (2-1-9).

5. A downhole multi-parameter online acquisition system for CO2 injection wells according to claim 3, characterized in that: The turbine signal measurement unit (2-2-5) has a measurement flow channel (2-2-9), in which the turbine blade assembly (2-2-5-1) is arranged. Support assemblies (2-2-5-2) supporting the rotation of the turbine blade assembly (2-2-5-1) are respectively arranged at both ends of the turbine blade assembly (2-2-5-1). The detection assembly (2-2-5-3) is arranged in the measurement flow channel (2-2-9). When CO2 flows in the measurement flow channel (2-2-9), it drives the turbine blade assembly (2-2-5-1) to rotate. The detection assembly (2-2-5-3) measures the CO2 flow rate by detecting the rotational speed of the turbine blade assembly (2-2-5-1).

6. A downhole multi-parameter online acquisition system for CO2 injection wells according to claim 5, characterized in that: The magnetic positioning measurement unit (2-2-7) includes a second magnet (2-2-7-1), a coil (2-2-7-2), and a coil support mechanism (2-2-7-3). The second magnet (2-2-7-1) is respectively installed at both ends of the coil (2-2-7-2). The coil support mechanism (2-2-7-3) is installed at the lower end of the measuring outer protective tube (2-2-12) to support the second magnet (2-2-7-1) and the coil (2-2-7-2).

7. A downhole multi-parameter online acquisition system for CO2 injection wells according to claim 3, characterized in that: The measurement communication unit (2-2-4) includes a measurement code transmitting circuit (2-2-4-1) and a measurement decoding circuit (2-2-4-2); the measurement master control unit (2-2-1) controls the measurement code transmitting circuit (2-2-4-1) to communicate with the ground controller (1) through the encoding of the returned-biased Man code sequence to realize the uploading of CO2 parameter data and the reply of each command; the measurement master control unit (2-2-1) receives the instructions sent by the ground controller (1) from the measurement decoding circuit (2-2-4-2) and processes and replies to the instructions; the measurement code transmitting circuit (2-2-4-1) converts the returned-biased Man code encoded signal output by the measurement master control unit (2-2-1) into a returned-biased Man code waveform and uploads it to the ground controller (1) through the DC carrier bus (3); the measurement decoding circuit (2-2-4-2) converts the returned-biased Man code waveform sent by the ground controller (1) into a TTL level serial port signal and inputs it to the measurement master control unit (2-2-1).

8. The acquisition method of a downhole multi-parameter online acquisition system for CO2 injection wells according to any one of claims 1-7, characterized in that: Includes the following steps: Step S1: Place the downhole measuring instrument (2) at the upper part of the injection device (7) of the tubing joint (9); In step S2, the host computer (6) sends a command to the ground controller (1) to open the rubber tube. The ground controller (1) controls the downhole measuring instrument (2) to open the collecting rubber tube (2-1-9) and set the oil pipe (5). The CO2 in the oil pipe (5) passes through the internal flow channel of the downhole measuring instrument (2). Step S3: CO2 flow rate is calculated when CO2 passes through turbine signal measurement unit (2-2-5); CO2 temperature and pressure at injection well location where downhole measuring instrument (2) is located are measured by pressure and temperature measurement unit (2-2-6), and the CO2 injection amount of oil layer is obtained by combining CO2 flow rate. In step S4, the host computer (6) issues a command to close the rubber tube, and the ground controller (1) controls the downhole measuring instrument (2) to retract the collecting rubber tube (2-1-9); Step S5, continue to raise or lower the downhole measuring instrument (2), and measure the CO2 injection amount of each oil layer in sequence according to steps S1-S3.

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