A wireless zonal gas injection system and method for CO2 injection wells

Abstract

The present application relates to a kind of wireless regulation and control layer injection gas system and method for CO2 injection well, the injection gas system includes ground controller and multiple downhole intelligent gas distributor, multiple the downhole intelligent gas distributor is sequentially lowered into injection well by tubing connection respectively in injection gas layer, wherein, ground controller and each downhole intelligent gas distributor are communicated using wireless wave code communication mode, ground controller is monitored and flow control to the acquisition data of each layer downhole intelligent gas distributor in injection well by wireless wave code communication mode, ground controller and the acquisition data are analyzed and handled, then wireless regulation and control the CO2 injection amount of each layer downhole intelligent gas distributor.The present application is monitored in real time by the bidirectional wireless wave code communication of ground controller and downhole intelligent gas distributor, and the data such as temperature, pressure, density, flow rate of layering are monitored in real time, while the realization of wireless wave code communication mode, can not need anticorrosive wire, anticorrosive cable, also can realize pressure operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oilfield separate layer gas injection, and particularly relates to a wireless regulation and control separate layer gas injection system and method for a CO2 injection well. BACKGROUND

[0002] Since CO2 (carbon dioxide) is a gas with high solubility in oil and water, when it is dissolved in large quantities in crude oil, it can make the crude oil expand in volume, reduce the viscosity, and also reduce the interfacial tension between oil and water. In the aspect of gas injection in oilfields, CO2 oil displacement has the significant advantages of large applicable range, low oil displacement cost and high oil recovery rate compared with other oil displacement technologies.

[0003] At present, oil displacement by injecting CO2 into formations is increasingly valued by the industry, on the one hand due to the needs of oilfield development, and on the other hand due to the needs of greenhouse gas emission reduction. CO2 oil displacement technology has been developed for many years, and the current gas injection technology is mainly bulk injection, but bulk injected CO2 will rush along the direction with high permeability, causing gas channeling and resulting in ineffective utilization of oil layers, so CO2 separate layer injection technology is needed to improve the development effect of oilfields.

[0004] At present, CO2 separate layer injection technology is not mature enough, one type of existing technology is to use double tube separate injection, which increases the cost of a set of pipe column, is only suitable for two-layer separate injection wells, and has serious problems of pipeline corrosion and gas channeling sealing; another type is to use a mechanical structure of downhole gas distributor, which needs to use a wire to measure and adjust the instrument, and cannot realize automatic adjustment of downhole separate layer gas volume, accurate measurement of downhole supercritical CO2 flow, and real-time recording of separate layer flow, pressure, temperature and other data. SUMMARY

[0005] In view of the above problems, the present application aims to provide a wireless regulation and control separate layer gas injection system and method for a CO2 injection well, which uses a surface controller to realize real-time monitoring and flow regulation of data collected by a downhole intelligent gas distributor through a wireless wave code communication mode, can realize fine regulation of separate layer gas volume and accurate measurement of downhole supercritical CO2, and solves the problems of uneven longitudinal injection, gas channeling and corrosion during bulk injection of CO2.

[0006] To achieve the above-mentioned purposes, the present application adopts the following technical solutions:

[0007] A wireless regulation and control layer-by-layer gas injection system for CO2 injection wells, comprising a ground controller and a plurality of downhole intelligent gas distributors, the plurality of downhole intelligent gas distributors are sequentially lowered into the gas injection layers of the injection wells through the tubing connection respectively, characterized in that: the ground controller and each downhole intelligent gas distributor adopt wireless wave code communication mode for communication, the ground controller performs real-time monitoring and flow regulation on the collected data of each downhole intelligent gas distributor of the injection well through wireless wave code communication mode, the ground controller analyzes and processes the collected data, and then wirelessly regulates the CO2 injection amount of each downhole intelligent gas distributor.

[0008] Further, the ground controller comprises a controller wireless communication unit, and the downhole intelligent gas distributor comprises a gas distributor main control assembly, the gas distributor main control assembly comprises a gas distributor wireless communication unit, and the controller wireless communication unit and the gas distributor wireless communication unit communicate through wireless wave code communication mode.

[0009] Further, the ground controller further comprises a controller main control unit, a wellhead parameter acquisition unit and a ground electric adjustment mechanism, the receiving part of the controller wireless communication unit is connected with the pressure wave change acquisition in the wellhead parameter acquisition unit of the controller main control unit, and the sending part of the controller wireless communication unit is connected with the ground electric adjustment mechanism; the controller main control unit realizes ground flow regulation through the controller wireless communication unit and the ground electric adjustment mechanism and generates a sending code of ground wireless wave code communication to realize the sending of data from the ground to the downhole.

[0010] Further, the gas distributor main control assembly further comprises a gas distributor main control unit, a gas distributor wireless communication unit, a downhole parameter acquisition unit and a gas nozzle regulation unit, the receiving part of the gas distributor wireless communication unit is connected with the pressure wave change acquisition in the downhole parameter acquisition unit of the gas distributor main control unit; the sending part of the gas distributor wireless communication unit is connected with the gas nozzle regulation unit, the gas distributor main control unit realizes downhole flow regulation through the gas distributor wireless communication unit and the gas nozzle regulation unit and generates a sending code of downhole wireless wave code communication to realize the sending of data from the downhole to the ground.

[0011] Further, the downhole intelligent gas distributor further comprises an outer protective pipe, upper and lower ends of the outer protective pipe are respectively provided with an upper joint and a lower joint connected with the oil pipe, an inner shaft of the outer protective pipe is provided with a center flow pipe and a gas nozzle assembly, upper and lower ends of the center flow pipe are respectively communicated with the upper joint and the lower joint and are penetrated through the oil pipe at both ends; the gas nozzle assembly is inserted into the lower joint, an outer periphery of the lower joint is provided with a gas injection hole penetrated through a lower end of the gas nozzle assembly, an inner cavity of the lower joint is provided with a density flow detection hole communicated with the lower end of the center flow pipe and the lower end of the gas nozzle assembly, the inner cavity of the lower joint is further provided with a pressure and temperature detection hole penetrated through a cavity surface, and a main control assembly is arranged on the outer periphery of the center flow pipe and controls the gas nozzle assembly to adjust the CO2 injection amount of the gas injection hole.

[0012] Further, a lower end of the lower joint is provided with a downhole pressure sensor and a downhole temperature sensor communicated with the pressure and temperature detection hole, a downhole density flow detection assembly is arranged in the density flow detection hole, the gas nozzle assembly comprises a gas nozzle mechanism and an adjusting mechanism, the gas nozzle mechanism is arranged on the lower joint and is communicated with the gas injection hole and the density flow detection hole, a battery assembly is arranged in the outer protective pipe on the outer periphery of the center flow pipe, and the battery assembly is electrically connected with the main control assembly and the adjusting mechanism.

[0013] Further, the gas nozzle mechanism comprises a sleeve, an outer periphery of the sleeve is provided with a gas nozzle opening opposite to the gas injection hole, a valve core is arranged in the sleeve, one end of the valve core is connected with the adjusting mechanism, and the adjusting mechanism controls the valve core to move axially along the sleeve to open and close the opening degree of the gas nozzle opening.

[0014] Further, the gas nozzle adjusting unit is electrically connected with the adjusting mechanism, and the gas nozzle adjusting unit controls the adjusting mechanism to adjust the opening degree of the gas nozzle opening to control the CO2 injection amount.

[0015] The application further provides a wireless adjustment and control layered gas injection method for a CO2 injection well.

[0016] The method comprises the following steps:

[0017] Step S1, the downhole intelligent gas distributor is woken up from a dormant state, receives and analyzes a command sent by a ground controller;

[0018] Step S2, the downhole intelligent gas distributor judges whether an address in the received data matches an address of itself; if yes, the next step S3 is executed; if no, step S6 is executed;

[0019] Step S3, the downhole intelligent gas distributor judges that the command in the received data is a parameter reading command processing;

[0020] Step S4, the downhole intelligent gas distributor judges that the command in the received data is a control command processing;

[0021] Step S5, the downhole intelligent gas distributor answers the ground controller through the wireless wave code communication mode;

[0022] Step S6, the downhole intelligent gas distributor enters a dormant state.

[0023] Further, the step S1 is specifically waking up the downhole equipment through the agreed wake-up wave code rule, and then the downhole equipment starts to monitor the wave code sent by the ground controller, and analyzes the data according to the agreed wave code communication rule, so as to obtain the received data stream;

[0024] The step S2 is specifically judging whether the ground controller sends a command to the downhole intelligent gas distributor of the current layer, if yes, the address is matched, and the next step S3 is continuously executed, if not, the address is not matched, and the step S6 is executed;

[0025] The step S3 is specifically judging that the type of the sending command of the ground controller is a reading parameter command, and reading the corresponding temperature, pressure, density and flow data, and framing the data to be answered;

[0026] The step S4 is specifically judging that the type of the sending command of the ground controller is a control command, and the downhole intelligent gas distributor adjusts the opening degree of the gas nozzle according to the command requirement of the ground controller, so as to realize the regulation and control of the CO2 injection amount of the corresponding oil layer, and frames the response data of the execution result;

[0027] The step S5 is specifically that the downhole intelligent gas distributor sends the framed response data to the ground controller through the wireless wave code communication mode;

[0028] The step S6 is specifically that the downhole intelligent gas distributor reenters the low-power dormant state after completing the wireless wave code communication.

[0029] The present application has the following advantages due to the above technical scheme:

[0030] 1. In the wireless regulation and control layered gas injection system of the present application, the ground controller supports bidirectional communication with the downhole intelligent gas distributor in the wireless wave code communication mode, the downhole intelligent gas distributors of different layers are connected with the oil pipe and are lowered into the downhole together with the oil pipe, the downhole intelligent gas distributor of each layer is powered by a battery and communicates with the ground controller in the wireless wave code communication mode, the ground controller monitors the temperature, pressure, density and flow data of the layered data in real time, and the wireless wave code communication mode can be realized without the need of a corrosion-resistant steel wire and a corrosion-resistant cable, and can also realize pressure operation.

[0031] 2. In the wireless control stratified gas injection system of the present invention, since the throttling pressure difference of supercritical CO2 is relatively small, the central flow tube of the downhole intelligent gas distributor adopts an eccentric setting to form an eccentric CO2 flow channel to increase the throttling pressure difference, so as to meet the precise measurement of the volume flow rate of downhole supercritical CO2. Combined with the downhole parameter detection unit to detect the density, temperature and pressure parameters downhole, the mass flow rate of downhole supercritical CO2 can be accurately measured, thereby realizing the fine control of the stratified gas volume of the CO2 injection well and the accurate measurement of the downhole supercritical CO2 flow.

[0032] 3. Compared with the method of using double-tube injection technology and mechanical structure of downhole gas distributor for measurement and adjustment, the wireless control stratified gas injection system and method of the present invention adopts wireless wave code communication to realize automatic adjustment of downhole stratified gas volume and acquisition of stratified flow, pressure and temperature parameters. Since wireless wave code communication is a mature communication technology, the system and method of the present invention are simple to construct, simple to operate, pollution-free, low-cost, and also support remote adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a structural schematic diagram of a wireless controlled stratified gas injection system for a CO2 injection well provided by the present invention.

[0034] Figure 2 This is a principle block diagram of the ground controller of the present invention.

[0035] Figure 3 This is a principle block diagram of the main control component of the downhole intelligent gas distributor of the present invention.

[0036] Figure 4 This is an isometric structural diagram of the downhole intelligent gas distributor of the present invention.

[0037] Figure 5 for Figure 4 AA-direction cross-sectional enlarged structural diagram.

[0038] Figure 6 for Figure 4 BB-direction cross-sectional enlarged structural diagram.

[0039] Figure 7 It is an enlarged structural diagram of the air nozzle mechanism of the present invention in the closed state of the air nozzle opening.

[0040] Figure 8 It is an enlarged structural diagram of the air nozzle mechanism of the present invention in the open state of the air nozzle opening.

[0041] Figure 9 It is a schematic diagram of the enlarged structure of the air nozzle opening of the air nozzle mechanism of the present invention.

[0042] Figure 10 for Figure 9 Top view of .

[0043] Figure 11 A communication flow chart of a wireless regulation and layer injection gas method for a CO2 injection well is provided.

[0044] The reference signs in the drawings are as follows:

[0045] 1 ground controller; 1-1 power supply management unit; 1-2 controller master control unit; 1-3 wellhead parameter acquisition unit; 1-4 remote communication unit; 1-5 controller wireless communication unit; 1-6 ground electric adjustment mechanism;

[0046] 2 downhole intelligent gas distributor; 2-1 upper joint; 2-2 outer protective tube; 2-3 battery assembly; 2-4 gas nozzle assembly; 2-5 central flow tube; 2-6 master control assembly; 2-7 lower joint; 2-8 downhole measurement assembly plug; 2-9 downhole density flow detection assembly, 2-10 downhole temperature sensor, 2-11 downhole pressure sensor;

[0047] 2-4-1 gas nozzle mechanism; 2-4-2 adjustment mechanism; 2-4-11 sleeve; 2-4-12 valve cover; 2-4-13 valve rod; 2-4-14 valve core; 2-4-15 gas nozzle port;

[0048] 2-6-1 battery management unit; 2-6-2 gas distributor master control unit; 2-6-3 downhole parameter acquisition unit; 2-6-4 data storage unit; 2-6-5 gas distributor wireless communication unit; 2-6-6 gas nozzle regulation unit; 2-7-1 gas injection hole; 2-7-2 gas nozzle assembly insertion hole; 2-7-3 density flow detection hole; 2-7-4 pressure and temperature detection hole;

[0049] 3 tubing; 4 packer. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, so that the purpose, characteristics and advantages of the present application can be more clearly understood. It should be understood that the embodiments shown in the drawings are not a limitation on the scope of the present application, but are only to illustrate the essential spirit of the technical solutions of the present application.

[0051] As Figure 1The application provides a wireless regulation and control layered gas injection system for a CO2 injection well, which comprises a ground controller 1 and a plurality of downhole intelligent gas distributors 2, the plurality of downhole intelligent gas distributors 2 are connected in sequence by oil pipes 3 and then are lowered into designated gas injection layers of the injection well, wherein the ground controller 1 and each downhole intelligent gas distributor 2 are communicated in a wireless wave code communication mode, the ground controller 1 monitors and controls the flow of the collected data of each downhole intelligent gas distributor 2 of the injection well in real time through the wireless wave code communication mode, and then analyzes and processes the collected data of each layer and wirelessly controls the CO2 injection amount of each downhole intelligent gas distributor 2.

[0052] Specifically, the ground controller 1 is generally installed in a field control box, supports wired or wireless communication with a remote monitoring platform, monitors the changes of wellhead temperature, pressure and flow in real time and controls the CO2 injection amount of the ground. The downhole intelligent gas distributors 2 of different layers are connected with the oil pipes 3 and are lowered into the designated gas injection layers of the injection well along the oil pipes 3, and the downhole intelligent gas distributors 2 at the upper end of each gas injection layer are connected with packers 4 through the oil pipes 3. Each downhole intelligent gas distributor 2 supports the monitoring of downhole temperature, pressure, density and flow, and supports the storage of collected data.

[0053] According to the control command of the ground controller 1, the downhole intelligent gas distributor 2 can be adjusted to control the CO2 injection amount of each gas injection layer of the injection well, the ground controller 1 and the downhole intelligent gas distributor 2 are communicated in a wireless wave code communication mode, the wireless wave code communication mode does not need to use anticorrosive cables and can realize pressure operation.

[0054] Further, the ground controller 1 comprises a controller wireless communication unit 1-5, the downhole intelligent gas distributor 2 is provided with a main control assembly 2-6, the main control assembly 2-6 comprises a gas distributor wireless communication unit 2-6-5, and the controller wireless communication unit 1-5 and the gas distributor wireless communication unit 2-6-5 are communicated in a wireless wave code communication mode. The gas distributor wireless communication units 2-6-5 of the downhole intelligent gas distributors 2 of different layers and the controller wireless communication unit 1-5 of the ground controller 1 realize bidirectional communication in a wireless wave code communication mode.

[0055] As shown in the Figure 2 Specifically, the ground controller 1 comprises a power supply management unit 1-1, a controller main control unit 1-2, a wellhead parameter acquisition unit 1-3, a remote communication unit 1-4, a controller wireless communication unit 1-5 and a ground electric adjustment mechanism 1-6.

[0056] The power supply input end of the power supply management unit 1-1 is connected with the power supply interface of the field AC 220V alternating current power supply, converts the input AC 220V alternating current power supply into 24V direct current power supply, and then converts the 24V direct current power supply into different power supply voltages required by the system work. The power supply output end of the power supply management unit 1-1 is electrically connected with the power supply input end of the controller master unit 1-2, the wellhead parameter acquisition unit 1-3, the remote communication unit 1-4 and the ground electric adjustment mechanism 1-6 respectively.

[0057] The controller master unit 1-2 is connected with the wellhead parameter acquisition unit 1-3 through SPI (serial peripheral interface), and is connected with the remote communication unit 1-4 through serial UART (universal asynchronous receiver transmitter) interface.

[0058] The controller master unit 1-2 is composed of an embedded computer hardware platform and system management software, and is provided with a software processing unit of the controller wireless communication unit 1-5 in the controller master unit 1-2. The controller master unit 1-2 is responsible for data acquisition, communication and control functions of the whole system, realizes data acquisition processing, control, communication and data storage management of the whole system. The controller master unit 1-2 is connected with the wellhead parameter acquisition unit 1-3, the remote communication unit 1-4 and the ground electric adjustment mechanism 1-6 through the provided sensing data acquisition interface, control interface and communication interface respectively.

[0059] The wellhead parameter acquisition unit 1-3 is responsible for the temperature, pressure and flow acquisition functions of the system, and the input end of the wellhead parameter acquisition unit 1-3 is connected with a wellhead temperature sensor, a wellhead pressure sensor and a wellhead flow sensor respectively. The output end of the wellhead parameter acquisition unit 1-3 is connected with the controller master unit 1-2 through SPI (serial peripheral interface), and transmits the temperature, pressure and flow data of the wellhead to the controller master unit 1-2.

[0060] The remote communication unit 1-4 is responsible for the remote communication function between the ground controller 1 and the remote monitoring platform, one end of the remote communication unit 1-4 is connected with the controller master unit 1-2 through serial UART interface, and the other end of the remote communication unit 1-4 supports wired RS485 bus or RJ45 network port or wireless communication connection with the remote server communication interface of the remote monitoring platform.

[0061] The controller wireless communication unit 1-5 is composed of a wireless wave code communication receiving and sending unit and a communication encoding and decoding algorithm, and is responsible for receiving the temperature, pressure, density and flow data and the like collected by the downhole intelligent gas distributor 2 of different layers, and simultaneously controls the opening degree of the gas nozzle 2-4-15 of the downhole intelligent gas distributor 2 of different layers to adjust the injection amount of CO2 of each layer.

[0062] The controller wireless communication unit 1-5 realizes the function of bidirectional communication of wireless wave code in cooperation with the controller host unit 1-2, the wellhead parameter acquisition unit 1-3 and the ground electric adjustment mechanism 1-6. The receiving part of the controller wireless communication unit 1-5 (i.e. the data that the underground intelligent gas distributor answers in the mode of wireless wave code communication) is connected with the wellhead parameter acquisition unit 1-3 in the controller host unit 1-2, which acquires the pressure wave change (i.e. the change value of pressure detected by the wellhead pressure sensor in the wellhead parameter acquisition unit 1-3 to judge the communication data of wireless wave code. For example, if the underground intelligent gas distributor 2 needs to send a logic 1, the underground intelligent gas distributor 2 needs to adjust the pressure to 1 MPa through the control nozzle adjustment unit 2-6-6, and if the underground intelligent gas distributor 2 needs to send a logic 0, the underground intelligent gas distributor 2 adjusts the pressure to 0.1 MPa through the control nozzle adjustment unit 2-6-6. After the wave code communication coding rule is determined, the ground controller 1 and the underground intelligent gas distributor 2 perform data transmission and reception according to the rule), and then realizes the reception of underground data through decoding algorithm. The sending part of the controller wireless communication unit 1-5 (i.e. the data that the ground controller sends to the underground intelligent gas distributor in the mode of wireless wave code communication) is connected with the ground electric adjustment mechanism 1-6, and the controller host unit 1-2 realizes the sending code of ground wireless wave code communication by controlling the ground electric adjustment mechanism 1-6 connected with the controller wireless communication unit 1-5 and the ground flow adjustment, and realizes the sending of data from the ground to the underground. When the ground flow adjustment is performed, the pre-determined wave code communication coding rule is executed, i.e. the ground controller 1 needs to send data to the underground intelligent gas distributor 2, the ground controller 1 needs to adjust the electric adjustment valve on the ground through the ground electric adjustment mechanism 1-6 to generate different pressures, and the underground intelligent gas distributor 2 can realize wireless wave code communication by identifying different pressures.

[0063] The ground electric adjustment mechanism 1-6 is composed of an adjustment valve assembly and an electric adjustment valve, and the adjustment valve assembly is connected with the controller host unit 1-2 through RS485 bus or 4~20mA current loop interface, mainly responsible for the flow control of ground injection of liquid CO2, and also serves as the execution mechanism of the sending wave code of the controller wireless communication unit 1-5 of the ground controller 1.

[0064] As shown in Figure 3 Specifically, the host assembly 2-6 of the underground intelligent gas distributor 2 includes a battery management unit 2-6-1, a gas distributor host unit 2-6-2, a downhole parameter acquisition unit 2-6-3, a data storage unit 2-6-4, a gas distributor wireless communication unit 2-6-5 and a nozzle adjustment unit 2-6-6.

[0065] The input end of the battery management unit 2-6-1 is connected with the master control unit battery and motor battery for obtaining power supply, the output end of the battery management unit 2-6-1 is connected with the air distributor master control unit 2-6-2, the downhole parameter acquisition unit 2-6-3, the data storage unit 2-6-4 and the gas nozzle control unit 2-6-6 respectively for power supply of the air distributor master control unit 2-6-2, the downhole parameter acquisition unit 2-6-3, the data storage unit 2-6-4 and the gas nozzle control unit 2-6-6. The battery management unit 2-6-1 comprises a battery power detection circuit and a low-power control circuit for detecting the battery circuit and system power consumption.

[0066] The air distributor master control unit 2-6-2 is mainly used for downhole sensing data detection, gas nozzle port 2-4-15 regulation, measurement and data storage management and wireless wave code communication function. The air distributor master control unit 2-6-2 is electrically connected with the battery management unit 2-6-1, the downhole parameter acquisition unit 2-6-3, the data storage unit 2-6-4 and the gas nozzle control unit 2-6-6 respectively. The air distributor master control unit 2-6-2 comprises a single-chip microcomputer and a peripheral control circuit, and the single-chip microcomputer preferably adopts DSPIC30F6010-20E.

[0067] The air distributor master control unit 2-6-2 is connected with the battery power detection circuit of the battery management unit 2-6-1 through two-way ADC (analog-digital conversion) interfaces, and is connected with the low-power control circuit of the battery management unit 2-6-1 through a GPIO (general input-output port). The air distributor master control unit 2-6-2 collects and controls the power consumption of the battery management unit 2-6-1 through the battery power detection circuit and the low-power control circuit. Meanwhile, the air distributor master control unit 2-6-2 is provided with a software processing unit of the air distributor wireless communication unit 2-6-5, the air distributor wireless communication unit 2-6-5 is responsible for wireless wave code communication encoding and decoding algorithm processing, and the air distributor master control unit 2-6-2 is connected with the control circuit part of the gas nozzle control unit 2-6-6 through two GPIOs (general input-output ports).

[0068] The downhole parameter acquisition unit 2-6-3 is used for sensing and collecting downhole temperature, pressure, density and flow data and data filtering processing. The input end of the downhole parameter acquisition unit 2-6-3 is connected with a downhole temperature sensor 2-10, a downhole pressure sensor 2-11 and a downhole density flow detection assembly 2-9 respectively, and the downhole temperature sensor 2-10, the downhole pressure sensor 2-11 and the downhole density flow detection assembly 2-9 are used for detecting the temperature, pressure, density and flow of the injected CO2 respectively. The output end of the downhole parameter acquisition unit 2-6-3 is connected with the air distributor master control unit 2-6-2 through an SPI (serial peripheral interface).

[0069] In the downhole parameter acquisition unit 2-6-3, the downhole temperature sensor 2-10 is preferably a high-precision PT1000 sensor, the downhole pressure sensor 2-11 is preferably a high-precision imported single-crystal silicon sensor, and the downhole density flow detection assembly 2-9 is composed of a downhole density sensor and a downhole flowmeter, wherein the downhole flowmeter is preferably a multi-stage partial-orifice differential pressure flowmeter, and the downhole density sensor is preferably a tuning fork detection type.

[0070] Since the throttling pressure difference of supercritical CO2 is relatively small, the multi-stage partial-orifice differential pressure flowmeter is used to increase the throttling pressure difference, which can meet the accurate measurement of the downhole supercritical CO2 volume flow, and in combination with the density value detected by the downhole density sensor and the downhole temperature pressure density compensation algorithm, the mass flow of the downhole supercritical CO2 can be accurately measured.

[0071] The data storage unit 2-6-4 is used for the storage of downhole data, the recording of system running state and events. The data storage unit 2-6-4 is connected with the gas distributor main control unit 2-6-2 through SPI (serial peripheral interface).

[0072] The gas distributor wireless communication unit 2-6-5 is mainly composed of a wireless wave code communication receiving and sending unit and a communication encoding and decoding algorithm, and is responsible for receiving different commands sent by the ground controller 1 and executing different actions according to different commands. For example: the ground wants to obtain the measurement parameters of different layers in the well, and the downhole intelligent gas distributor 2 of the corresponding layer will respond to the ground controller 1 with the temperature, pressure, density and flow data collected after encoding; the ground controller 1 wants to control the CO2 injection amount of different layers in the well, and the downhole intelligent gas distributor 2 of the corresponding layer adjusts the opening size of the gas nozzle 2-4-15 according to the requirements of the ground controller 1.

[0073] The receiving part of the gas distributor wireless communication unit 2-6-5 (i.e. the data that the downhole intelligent gas distributor wireless wave code communication answers to the ground controller in the wireless wave code communication mode) is connected to the pressure wave change acquisition in the downhole parameter acquisition unit 2-6-3 of the gas distributor master control unit 2-6-2 of the downhole intelligent gas distributor 2 (i.e. the pressure change value detected by the downhole pressure sensor 2-11 in the downhole parameter acquisition unit 2-6-3 is used to judge the communication data of the wireless wave code), and then the ground data is received through the decoding algorithm; the sending part of the gas distributor wireless communication unit 2-6-5 (i.e. the data that the downhole intelligent gas distributor wireless wave code communication sends to the ground controller in the wireless wave code communication mode) is connected with the gas nozzle control unit 2-6-6, and the gas distributor master control unit 2-6-2 realizes the sending code of the downhole wireless wave code communication through the gas distributor wireless communication unit 2-6-5 and the connected gas nozzle control unit 2-6-6, realizes the sending code of the downhole to the ground data, so as to realize the bidirectional wireless wave code communication between the ground controller 1 and the downhole intelligent gas distributor 2. At the same time, the realization of the wireless wave code communication mode does not need the corrosion-resistant wire and the corrosion-resistant cable, and can also realize the operation under pressure.

[0074] The gas nozzle control unit 2-6-6 is connected with the gas distributor master control unit 2-6-2 through two GPIOs (general input and output ports), and the gas nozzle control unit 2-6-6 is connected with the adjusting mechanism 2-4-2 inside the gas nozzle assembly 2-4 at the same time for controlling the adjusting mechanism 2-4-2 to regulate the opening of the gas nozzle port 2-4-15 to control the flow of injected CO2. The gas nozzle control unit 2-6-6 simultaneously serves as the executing mechanism of the sending wave code of the gas distributor wireless communication unit 2-6-5.

[0075] As shown in Figure 4 , Figure 5 , Figure 6 Further, the downhole intelligent gas distributor 2 comprises an outer protective pipe 2-2, an upper joint 2-1 and a lower joint 2-7 are arranged at the upper end and the lower end of the outer protective pipe 2-2 respectively and connected with the oil pipe 3, a central flow pipe 2-5 and a gas nozzle assembly 2-4 are arranged axially in the outer protective pipe 2-2, the central flow pipe 2-5 is communicated with the upper joint 2-1 and the lower joint 2-7 and penetrates through the oil pipe 3 at both ends, the gas nozzle assembly 2-4 is inserted in the lower joint 2-7, a gas injection hole 2-7-1 is arranged on the outer periphery of the lower joint 2-7 and penetrates through the lower end of the gas nozzle assembly 2-4, a density flow detection hole 2-7-3 is arranged in the inner cavity of the lower joint 2-7 and communicated with the lower end of the central flow pipe 2-5 and the lower end of the gas nozzle assembly 2-4, and the master control assembly 2-6 is arranged on the outer periphery of the central flow pipe 2-5 and controls the gas nozzle assembly 2-4 to adjust the CO2 injection amount from the gas injection hole 2-7-1.

[0076] Specifically, the upper joint 2-1 and the lower joint 2-7 are used to be screwed with the tubing 3 of different layers, the downhole intelligent gas distributor 2 is connected in series in the tubing 3, the downhole intelligent gas distributors 2 of different gas injection layers are connected in series at different positions of the tubing 3, and finally the tubing 3 is lowered into the gas injection well as a whole. The center flow pipe 2-5 is a CO2 flow channel, the material of the center flow pipe 2-5 is 13Cr stainless steel which can resist carbon acid corrosion for a long time, the upper joint 2-1 and the lower joint 2-7 are eccentric sleeve pipe structures, the eccentric arrangement of the center flow pipe 2-5 relative to the axis of the downhole intelligent gas distributor 2 can effectively utilize the space to reduce the outer diameter size of the outer protective pipe 2-2, the center flow pipe 2-5 is connected with the upper joint 2-1 and the lower joint 2-7 of the downhole intelligent gas distributor, and the connection is sealed to form the CO2 flow channel.

[0077] The lower joint 2-7 is axially provided with a gas nozzle assembly insertion hole 2-7-2, the gas nozzle assembly 2-4 is inserted in the gas nozzle assembly insertion hole 2-7-2 and connected with the gas injection hole 2-7-1, the density flow detection hole 2-7-3 is axially arranged on one side of the gas nozzle assembly insertion hole 2-7-2 and close to the inner cavity wall of the lower joint 2-7, the downhole density flow detection assembly 2-9 is arranged in the density flow detection hole 2-7-3, the upper end of the density flow detection hole 2-7-3 is sealed by the embedded downhole measurement assembly plug 2-8, the lower end of the density flow detection hole 2-7-3 is provided with a first inclined hole penetrating the density flow detection hole 2-7-3 and the inner cavity of the lower joint 2-7, and the upper end of the density flow detection hole 2-7-3 is provided with a second inclined hole connected with the gas nozzle assembly 2-4, the CO2 of the center flow pipe 2-5 enters the gas nozzle assembly 2-4 through the density flow detection hole 2-7-3, the CO2 injection amount is controlled by the gas nozzle assembly, and the CO2 is discharged from the gas injection hole 2-7-1.

[0078] Further, the upper end of the lower joint 2-7 is provided with the downhole pressure sensor 2-11 and the downhole temperature sensor 2-10, the inner cavity of the lower joint 2-7 is provided with a pressure and temperature detection hole 2-7-4 penetrating the downhole pressure sensor 2-11 and the downhole temperature sensor 2-10, the density flow detection hole 2-7-3 is provided with the downhole density flow detection assembly 2-9, the gas nozzle assembly 2-4 includes a gas nozzle mechanism 2-4-1 and an adjusting mechanism 2-4-2, the gas nozzle mechanism 2-4-1 is arranged on the lower joint 2-7 and connected with the gas injection hole 2-7-1 and the density flow detection hole 2-7-3, the outer protective pipe 2-2 of the outer periphery of the center flow pipe 2-5 is provided with a battery assembly 2-3, and the battery assembly 2-3 is electrically connected with the main control assembly 2-6 and the adjusting mechanism 2-4-2.

[0079] Specifically, the upper end of the lower joint 2-7 is axially provided with a pressure temperature detection hole 2-7-4, the pressure temperature detection hole 2-7-4 is radially provided with a third inclined hole and the inner cavity of the lower joint 2-7, and the bottom of the pressure temperature detection hole 2-7-4 is radially provided with a fourth horizontal hole and the bottom of the pressure temperature detection hole 2-7-4. The downhole pressure sensor 2-11 and the downhole temperature sensor 2-10 are installed on the pressure temperature detection hole 2-7-4. The crude oil in the oil pipe 3 enters the pressure temperature detection hole 2-7-4 through the third inclined hole and the fourth horizontal hole, and the downhole pressure sensor 2-11 and the downhole temperature sensor 2-10 realize the detection of the downhole oil layer temperature, the inside and outside of the oil pipe, and the detection data is transmitted to the main control assembly 2-6. The main control assembly 2-6 can realize two-way communication with the ground controller 1 by adjusting the movement of the gas nozzle assembly 2-4.

[0080] The adjusting mechanism 2-4-2 is a lead screw mechanism driven by a motor, and the motor drives the axial movement of the lead screw to adjust the gas nozzle mechanism 2-4-1.

[0081] The battery assembly 2-3 includes a main control system battery and a motor battery. The main control system battery is connected to the power supply terminal of the main control assembly 2-6 through a high-temperature lead, and one end of the motor battery is connected to the power supply terminal of the motor in the adjusting mechanism 2-4-2 through a high-temperature lead. The motor is connected to and controlled by the main control assembly 2-6.

[0082] The wireless wave code receiving part of the main control assembly 2-6 collects the changes of the pressure wave in the oil pipe 3, decodes the changes, obtains the commands sent by the ground controller 1, and processes accordingly according to the commands. The wireless wave code sending part of the main control assembly 2-6 encodes the data to be sent, generates pressure wave codes in the oil pipe 3 by controlling the movement of the gas nozzle assembly 2-4, and the ground controller 1 receives the changes of the pressure wave codes, decodes the changes, and obtains downhole temperature, pressure, and other data information.

[0083] As shown in Figure 7 , Figure 8 , Figure 9 , Figure 10 Further, the gas nozzle mechanism 2-4-1 includes a sleeve 2-4-11, the outer periphery of the sleeve 2-4-11 is provided with a gas nozzle port 2-4-15 opposite to the gas injection hole 2-7-1, the sleeve 2-4-11 is provided with a valve core 2-4-14, one end of the valve core 2-4-14 is connected to the adjusting mechanism 2-4-2, and the adjusting mechanism 2-4-2 controls the valve core 2-4-14 to move axially along the sleeve 2-4-11 to open and close the opening degree of the gas nozzle port 2-4-15.

[0084] Specifically, the sleeve 2-4-11 and the valve core 2-4-14 are sleeved with an annular valve cover 2-4-12, the valve core 2-4-14 is nested inside the valve cover 2-4-12, the valve cover 2-4-12 drives the valve core 2-4-14 to move axially along the sleeve 2-4-11, and the valve rod 2-4-13 is connected with the valve cover 2-4-12 and the lead screw of the adjusting mechanism 2-4-2 respectively.

[0085] The gas nozzle port 2-4-15 is located on the cylinder wall of the sleeve 2-4-11, when the valve cover 2-4-12 moves along the sleeve 2-4-11, the opening degree of the gas nozzle port 2-4-15 is adjusted by the stroke of the valve rod 2-4-13 and the valve core 2-4-14 pushed by the lead screw of the adjusting mechanism 2-4-2, and the opening degree (i.e. the opening area of the gas nozzle port) of the gas nozzle port 2-4-15 is controlled by the sequential movement of the valve cover 2-4-12 to realize the regulation of the CO2 injection amount. The shape of the gas nozzle port 2-4-15 is an arc-shaped isosceles triangular structure column hole which transitions from small to large, wherein the two waist sides of the triangle are convex arc lines. The gas nozzle port 2-4-15 satisfies the equal percentage flow regulation characteristic, the regulation curve slope increases with the increase of the stroke, under the same stroke change, the flow changes little when the flow is small, and the flow changes greatly when the flow is large, that is, the opening regulation of the gas nozzle port 2-4-15 is small, the slope is small, the regulation is stable and gentle, the opening regulation of the gas nozzle port 2-4-15 is large, the slope is large, the regulation sensitivity is good, the precision is high, and the on-site CO2 injection amount can be finely regulated.

[0086] The wireless regulation layered gas injection system of the present application can regulate the injection amount of CO2 in each layer of the injection well, and can regulate the injection amount of CO2 in each layer of the injection well in real time.

[0087] As shown in the figure. Figure 11 The present application also provides a wireless regulation layered gas injection method for a CO2 injection well, which uses the layered gas injection system described above, and comprises the following steps:

[0088] Step S1, the downhole intelligent gas distributor 2 is awakened from the dormant state, receives and analyzes the command sent by the ground controller 1. Specifically, the downhole intelligent gas distributor 2 decodes the received wireless wave code data and analyzes the command sent by the ground controller 1, first wakes up the downhole equipment according to the agreed wake-up wave code rule, then the downhole equipment starts to monitor the wave code sent by the ground controller 1, and analyzes the data according to the agreed wave code communication coding rule.

[0089] Step S2, the downhole intelligent gas distributor 2 judges whether the address in the received data matches its own address, if yes, it continues to execute the next step S3; if not, it jumps to step S6 to re-enter the dormant state.

[0090] Specifically, it judges whether the command sent by the ground controller 1 to the downhole intelligent gas distributor 2 of the current layer, if yes, the address matches, and it is ready for the next step S3; if not, the address does not match, and the downhole intelligent gas distributor 2 of the current layer will enter the dormant state and not perform any processing.

[0091] Step S3, the downhole intelligent gas distributor 2 judges that the command in the received data is a read parameter command processing. Specifically, it judges that the command type sent by the ground controller 1 is a read parameter command, and performs the reading of the corresponding temperature, pressure, density and flow data, and frames the data to be answered.

[0092] Step S4, the downhole intelligent gas distributor 2 judges that the command in the received data is a control command processing. Specifically, it judges that the command type sent by the ground controller 1 is a control command, and the downhole intelligent gas distributor 2 adjusts the opening of the gas nozzle 2-4-15 according to the command of the ground controller 1 to realize the regulation and control of the CO2 injection amount of the corresponding oil layer, and frames the response data of the execution result.

[0093] Step S5, the downhole intelligent gas distributor 2 answers the ground controller 1 through the wireless wave code communication mode. Specifically, the downhole intelligent gas distributor 2 sends the framed response data to the ground controller 1 through the wireless wave code communication mode.

[0094] Step S6, the downhole intelligent gas distributor 2 enters the dormant state. Specifically, after the downhole intelligent gas distributor 2 completes the communication through the wireless wave code, it re-enters the low-power dormant state to ensure that the downhole intelligent gas distributor 2 can work in the well for a long time.

[0095] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A wireless controlled stratified gas injection system for a CO2 injection well, comprising a surface controller (1) and a plurality of downhole intelligent gas distributors (2), wherein the plurality of downhole intelligent gas distributors (2) are connected via oil pipes (3) and sequentially lowered into the gas injection layer of the injection well, characterized in that: The surface controller (1) communicates with each of the downhole intelligent gas distributors (2) using a wireless wave code communication method. The surface controller (1) monitors and controls the flow of the collected data of each layer of the downhole intelligent gas distributor (2) injected into the well in real time through the wireless wave code communication method. The surface controller (1) also analyzes and processes the collected data, and then wirelessly controls the CO2 injection amount of each layer of the downhole intelligent gas distributor (2); The downhole intelligent gas distributor (2) comprises a main control component (2-6) and an outer protective tube (2-2), wherein the upper and lower ends of the outer protective tube (2-2) are respectively provided with an upper joint (2-1) and a lower joint (2-7) connected to the oil pipe (3), wherein the upper joint (2-1) and the lower joint (2-7) are both eccentric sleeve tubular structures, and a central flow tube (2-5) and a gas nozzle assembly (2-4) are axially provided in the inner part of the outer protective tube (2-2), wherein the upper and lower ends of the central flow tube (2-5) are respectively connected to the upper joint (2-1) and the lower joint ( 2-7) and then connected with the oil pipes (3) at both ends to form an eccentric CO2 flow channel; the gas nozzle assembly (2-4) is inserted into the lower joint (2-7), and the outer periphery of the lower joint (2-7) is provided with a gas injection hole (2-7-1) connected with the lower end of the gas nozzle assembly (2-4), and the inner cavity of the lower joint (2-7) is provided with a density flow detection hole (2-7-3) connected with the lower end of the central flow tube (2-5) and the lower end of the gas nozzle assembly (2-4), and the main control assembly (2-6) is provided on the The outer periphery of the central flow tube (2-5) is controlled to control the gas nozzle assembly (2-4) to adjust the CO2 injection amount of the gas injection hole (2-7-1); the inner cavity of the lower joint (2-7) is also provided with a pressure and temperature detection hole (2-7-4) that passes through the inner cavity circumference, and the upper end of the lower joint (2-7) is provided with a downhole pressure sensor (2-11) and a downhole temperature sensor (2-10) that are connected to the pressure and temperature detection hole (2-7-4), and the density flow detection hole (2-7-3) is provided with a downhole density flow detection sensor. The gas nozzle assembly (2-4) includes a gas nozzle mechanism (2-4-1) and an adjustment mechanism (2-4-2); the gas nozzle mechanism (2-4-1) is arranged on the lower joint (2-7) and is connected to the gas injection hole (2-7-1) and the density flow detection hole (2-7-3); a battery assembly (2-3) is arranged in the outer protective tube (2-2) on the outer periphery of the central flow tube (2-5); the battery assembly (2-3) is electrically connected to the main control assembly (2-6) and the adjustment mechanism (2-4-2).

2. A wireless controlled stratified gas injection system for a CO2 injection well according to claim 1, characterized in that: The ground controller (1) includes a controller wireless communication unit (1-5), and the main control component (2-6) further includes an air distributor wireless communication unit (2-6-5). The controller wireless communication unit (1-5) communicates with the air distributor wireless communication unit (2-6-5) via wireless wave code communication.

3. A wireless controlled stratified gas injection system for a CO2 injection well according to claim 2, characterized in that: The ground controller (1) further comprises a controller main control unit (1-2), a wellhead parameter acquisition unit (1-3) and a ground electric adjustment mechanism (1-6); a receiving part of the controller wireless communication unit (1-5) is obtained by pressure wave changes in the wellhead parameter acquisition unit (1-3) connected to the controller main control unit (1-2); a transmitting part of the controller wireless communication unit (1-5) is connected to the ground electric adjustment mechanism (1-6); the controller main control unit (1-2) realizes ground flow regulation through the controller wireless communication unit (1-5) and the ground electric adjustment mechanism (1-6) and cooperates to generate a transmission code for ground wireless wave code communication, thereby realizing the transmission of data from the ground to the downhole.

4. A wireless controlled stratified gas injection system for a CO2 injection well according to claim 2 or 3, characterized in that: The main control component (2-6) also includes a gas distributor main control unit (2-6-2), a gas distributor wireless communication unit (2-6-5), a downhole parameter acquisition unit (2-6-3) and a nozzle control unit (2-6-6). The receiving part of the gas distributor wireless communication unit (2-6-5) is obtained by the pressure wave change in the downhole parameter acquisition unit (2-6-3) connected to the gas distributor main control unit (2-6-2); the sending part of the gas distributor wireless communication unit (2-6-5) is connected to the nozzle control unit (2-6-6). The gas distributor main control unit (2-6-2) realizes downhole flow regulation through the gas distributor wireless communication unit (2-6-5) and the nozzle control unit (2-6-6) and cooperates to generate a sending code for downhole wireless wave code communication to realize the transmission of data from downhole to the ground.

5. The wireless controlled stratified gas injection system for CO2 injection wells according to claim 4, characterized in that: The air nozzle mechanism (2-4-1) includes a sleeve (2-4-11), the outer periphery of the sleeve (2-4-11) is provided with an air nozzle port (2-4-15) opposite to the air injection hole (2-7-1), a valve core (2-4-14) is provided in the sleeve (2-4-11), one end of the valve core (2-4-14) is connected to the regulating mechanism (2-4-2), and the regulating mechanism (2-4-2) controls the valve core (2-4-14) to move axially along the sleeve (2-4-11) to open and close the opening of the air nozzle port (2-4-15).

6. The wireless controlled stratified gas injection system for a CO2 injection well according to claim 5, characterized in that: The gas nozzle regulating unit (2-6-6) is electrically connected to the regulating mechanism (2-4-2), and the gas nozzle regulating unit (2-6-6) controls the regulating mechanism (2-4-2) to regulate the opening of the gas nozzle port (2-4-15) to control the CO2 injection amount.

7. A wireless controlled stratified gas injection method for a CO2 injection well, using a wireless controlled stratified gas injection system for a CO2 injection well according to any one of claims 1 to 6, characterized in that: The gas injection method comprises the following steps: Step S1, the downhole intelligent gas distributor (2) wakes up from a dormant state, receives and analyzes a command sent by the surface controller (1); Step S2, the downhole intelligent gas distributor (2) determines whether the address in the received data matches its own address; if it matches, it executes the next step S3; if it does not match, it executes step S6; Step S3, the downhole intelligent gas distributor (2) determines that the command in the received data is a parameter reading command; Step S4, the downhole intelligent gas distributor (2) determines that the command in the received data is a control command; Step S5, the underground intelligent gas distributor (2) responds to the surface controller (1) via wireless wave code communication; Step S6: the underground intelligent gas distributor (2) enters a dormant state.

8. The wireless controlled stratified gas injection method for a CO2 injection well according to claim 7, characterized in that: The step S1 specifically involves waking up the downhole equipment through the agreed wake-up wave code rule, and then the downhole equipment starts to monitor the wave code sent by the surface controller (1), and parses the data according to the agreed wave code communication rule; The step S2 is specifically to determine whether the ground controller (1) sends a command to the downhole intelligent gas distributor (2) at this layer. If so, the addresses match and the step S3 is continued; if not, the addresses do not match and the step S6 is executed; The step S3 specifically comprises determining that the type of command sent by the ground controller (1) is a parameter reading command, reading corresponding temperature, pressure, density and flow data, and framing the data to be responded; The step S4 is specifically to determine whether the type of command sent by the ground controller (1) is a control command, and the downhole intelligent gas distributor (2) adjusts the opening of the gas nozzle (2-4-15) according to the command requirement of the ground controller (1) to achieve the regulation of the CO2 injection amount of the corresponding oil layer, and at the same time, the response data of the execution result is framed; The step S5 is specifically that the downhole intelligent gas distributor (2) sends the framed response data to the surface controller (1) via wireless wave code communication; Said step S6 is specifically that after the downhole intelligent gas distributor (2) is completed via the wireless wave code communication mode, it re-enters the low-power sleep state.

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