An intelligent injection-production method for downhole carbon dioxide flooding in the same well based on wave code communication

Abstract

The present invention provides a downhole carbon dioxide flooding and same-well intelligent injection and production method based on wave code communication. First, a surface wave code communication controller uses wave code communication to adjust the gas nozzle to a gas injection mode, and gas injection is allocated to each layer in the downhole. After the gas injection time ends, the gas nozzle is adjusted to a well blocking mode, and each layer in the downhole is blocked for a preset time. Finally, after the well blocking time ends, the gas nozzle is adjusted to an oil production mode, and oil production begins in each layer in the downhole. Because the method of the present invention supports adjusting the gas nozzle operating mode and preset time through wave code, it can be used in a long-term cycle, solving the problem of supporting stratified gas injection and stratified oil production in a single well, improving oil production efficiency, and reducing production costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of stratified gas injection and oil recovery in oil and gas wells, and particularly relates to an intelligent injection and recovery method for downhole carbon dioxide flooding in the same well based on wave code communication. Background Art

[0002] In the long-term oil production process, secondary oil recovery technologies, primarily based on water flooding, are no longer sufficient for current oilfield conditions with high water content and low formation permeability. Traditional water flooding not only wastes significant water resources but also results in low recovery rates under current conditions. In response to the current call for environmental protection and water conservation, the exploration and development of tertiary oil recovery (TER) technologies to increase oil recovery has become a hot research topic in my country's oil industry. TER primarily involves injecting polymers or chemicals into oil reservoirs. Current TER research demonstrates the significant advantages of using CO2 (carbon dioxide) as a flooding medium, demonstrating its outstanding effectiveness in enhancing oil recovery, making this technology the most promising. Supercritical CO2, due to its lack of a liquid phase, high diffusion coefficient, and low viscosity, avoids clay swelling and liquid plugging, and possesses strong solubility, can form a mixed fluid with crude oil in the reservoir, thus achieving a unique oil recovery mechanism. Its powerful extraction capacity allows for the separation or vaporization of lighter components in the crude oil, reducing interfacial tension to form a miscible phase, while also reducing crude oil viscosity and causing volume expansion.

[0003] Most oil layers in my country's oilfields are distributed vertically. Due to the large variations in parameters such as crude oil viscosity, density, effective thickness, and formation permeability within these vertical layers, traditional blanket injection methods can lead to significant interlayer interference. Large injection volumes are injected into high-permeability layers, while the required injection volumes for medium and low permeability layers are largely unmet, making it difficult to effectively exploit these layers. CO2 channeling along the high-permeability layer results in significant variations in oil recovery across different layers, leading to suboptimal recovery. Therefore, a stratified injection method of supercritical CO2 is being adopted to effectively inject high, medium, and low permeability layers, thereby resolving the interlayer injection conflict in oilfield development, ensuring formation energy efficiency to enhance recovery, and ultimately achieving stable and efficient oilfield development. However, existing stratified gas injection in a single well cannot achieve stratified oil recovery within the same well, resulting in low injection-production efficiency. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a downhole carbon dioxide flooding and intelligent injection and production method in the same well based on wave code communication, which controls the working mode and preset time of the downhole gas nozzle through wave code communication, thereby realizing the stratified CO2 injection, well blocking and oil production functions of a single well, solving the problem that stratified gas injection and stratified oil production in a single well cannot be carried out in the same well, improving oil production efficiency and reducing production costs.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A downhole carbon dioxide flooding same-well intelligent injection and production method based on wave code communication is characterized by: first, a surface wave code communication controller adjusts a gas nozzle to a gas injection mode via wave code communication, and gas injection is deployed to each layer downhole; after the gas injection time ends, the gas nozzle is adjusted to a well blocking mode, and each layer downhole is blocked for a preset time; finally, after the well blocking time ends, the gas nozzle is adjusted to an oil production mode, and oil production begins in each layer downhole; specifically, the method comprises the following steps:

[0007] Step S1, wave code configuration preset time and gas nozzle working mode; specifically, the ground wave code communication controller sends a wave code communication signal to the same well intelligent injection and production device, and the same well intelligent injection and production device configures the preset time and the initial working mode of the gas nozzle through the wave code;

[0008] Step S2, gas injection mode process; specifically, after receiving the wave code communication signal, the intelligent injection and production device in the same well adjusts the gas nozzle working mode to enter the gas injection mode, and allocates gas injection to each layer;

[0009] Step S3, the well blocking mode process; specifically: after receiving the wave code communication signal, the intelligent injection and production device in the same well adjusts the gas nozzle working mode to enter the well blocking mode, and each layer blocks the well according to the preset time;

[0010] Step S4, oil production mode process; specifically: the ground wave code communication controller sends a wave code communication signal to the same well intelligent injection and production device, the same well intelligent injection and production device adjusts the gas nozzle working mode to enter the oil production mode, and each layer begins to produce oil;

[0011] Step S5, waiting for the re-wave code communication process; specifically, the intelligent injection and production device in the same well waits for the ground wave code communication controller to re-wave code communication operation. If no valid wave code communication is received from the ground wave code communication controller, it will be in a waiting state; if a valid wave code communication is received, step S1 will be re-executed.

[0012] Furthermore, the ground wave code communication controller includes a data and instruction main control unit; the same-well intelligent injection and production device includes a main control board assembly and a gas nozzle assembly. The data and instruction main control unit sends a wave code communication signal to the main control board assembly, and the main control board assembly sends a control instruction to the gas nozzle assembly and controls it to perform gas injection, well blocking and oil production.

[0013] Furthermore, during gas injection, the motor of the gas nozzle assembly adjusts the gas nozzle valve core to move backward to generate displacement with the gas nozzle valve sleeve, and the gas nozzle gradually opens. At this time, the supercritical carbon dioxide pushes open the one-way valve to enter the gas injection mode.

[0014] Furthermore, when the well is blocked, the motor of the gas nozzle assembly adjusts the gas nozzle valve core to move forward and generate displacement with the gas nozzle valve sleeve until the gas nozzle is closed, entering the well blocking mode.

[0015] Furthermore, during oil production, the motor of the air nozzle assembly adjusts the air nozzle valve core to move backward and generate displacement with the air nozzle valve sleeve until the air nozzle is fully opened, entering the oil production mode.

[0016] Furthermore, the gas nozzle is composed of a wedge-shaped opening for adjusting the injection amount of carbon dioxide and a square opening for oil production.

[0017] The present invention adopts the above technical solution, which has the following advantages and effects:

[0018] (1) The injection and production method of the present invention is to communicate with the underground same-well intelligent injection and production device through the wave code method by the ground wave code communication controller to control the working mode and preset time of the gas nozzle. First, the gas nozzle is adjusted to the gas injection mode, and the gas injection is adjusted to each layer; then, after the gas injection is completed, the gas nozzle is adjusted to the well blocking mode, and each layer is blocked according to the preset time; finally, after the well blocking time is completed, the gas nozzle is adjusted to the oil production mode, and each layer starts to produce oil. This method supports adjusting the gas nozzle working mode and preset time through wave code, can be used in a long-term cycle, solves the problem of a single well supporting stratified gas injection and stratified oil production, improves oil production efficiency, and reduces production costs.

[0019] (2) The injection and production method of the present invention enables a single well to simultaneously integrate stratified gas injection and stratified oil production with a wave code-configured recycling device, which can not only save the construction cost of the oil well, but also improve the efficient development of low-permeability and ultra-low-permeability oil wells, help maintain the stability of domestic crude oil production, and has great economic and social significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 (a) is a schematic diagram of the internal structure of part of the same-well intelligent injection-production device of the same-well intelligent injection-production method of the present invention.

[0021] Figure 1 (b) is a schematic diagram of the external structure of part of the same-well intelligent injection-production device of the same-well intelligent injection-production method of the present invention.

[0022] Figure 2 Schematic diagram of the gas injection mode structure of the injection-production method of the present invention.

[0023] Figure 3 It is a structural schematic diagram of the well blocking mode of the injection-production method of the present invention.

[0024] Figure 4 It is a schematic diagram of the oil production mode structure of the injection-production method of the present invention.

[0025] Figure 5Schematic diagram of the gas nozzle structure of the injection-production method of the present invention.

[0026] Figure 6 This is a flow chart of the injection-production method of the present invention.

[0027] In the accompanying drawings, the reference numerals are as follows:

[0028] 1-upper connector; 2-screw ring; 3-center flow tube; 4-power battery assembly; 5-main control board battery assembly; 6-gas nozzle assembly; 7-hole back pressure detection; 8-external pressure detection; 9-internal pressure detection unit; 10-screen; 11-lower connector; 12-outer casing; 13-main control board assembly; 14-plug; 15-check valve; 16-flow meter; 601:-gas nozzle valve sleeve; 602-gas nozzle valve core; 6011-gas nozzle; 1301-wave code configuration preset time and gas nozzle working mode; 1302-gas injection mode process; 1303-well blocking mode process; 1304-oil production mode process; 1305-waiting for re-wave code communication process. DETAILED DESCRIPTION

[0029] The following will be described in detail with reference to the accompanying drawings to provide a clearer understanding of the objectives, features and advantages of the present invention. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0030] The present invention provides a downhole carbon dioxide flooding and same-well intelligent injection and production method based on wave code communication. First, a ground wave code communication controller uses wave code communication to adjust the gas nozzle of the downhole carbon dioxide flooding and same-well intelligent injection and production device to a gas injection mode, and gas injection is allocated to each downhole oil layer. After the gas injection time ends, the gas nozzle is adjusted to a well blocking mode, and each downhole oil layer is blocked for a preset time. Finally, after the well blocking time ends, the gas nozzle is adjusted to an oil production mode, and oil production begins in each downhole oil layer. The method of the present invention supports adjusting the gas nozzle working mode and preset time through wave code, can be recycled for a long time, solves the problem of a single well supporting stratified gas injection and stratified oil production, improves oil production efficiency, and reduces production costs.

[0031] like Figure 1 (a) Figure 1(b) The present invention provides a downhole CO2 flooding, same-well intelligent injection and production method based on wave code communication, implemented by a surface wave code communication controller and a same-well intelligent injection and production device. The surface controller primarily includes a surface flow meter module, a flow control valve, a pressure sensor, an electric actuator, and a data and command control unit. The surface controller is primarily used for collecting and transmitting wellhead injection flow, pressure, and temperature data; wave code communication and analysis of downhole stratified flow, stratified pressure, and temperature data; wave code communication for adjusting gas nozzle operating modes, presetting times, and one-touch seal verification; receiving and executing remote control system commands; and providing constant pressure, constant flow, and opening adjustment functions.

[0032] The upper joint 1, screw ring 2, central flow tube 3, screen 10, lower joint 11, outer casing 12 and plug 14 of the same-well intelligent injection and production device constitute an internal annulus area, and the power battery assembly 4, main control board battery assembly 5, gas nozzle assembly 6, backhole pressure detection 7, external pressure detection 8, internal pressure detection unit 9, main control board assembly 13, one-way valve 15 and flow meter 16 are respectively installed on the lower joint 11 in the internal annulus area through threads.

[0033] The intelligent injection and production device in the same well is mainly used for collecting downhole stratified pressure, temperature, and flow data and transmitting wave codes; adjusting the water nozzle working mode according to preset time or instructions; and automatic sealing function. Through program control, it executes the gas injection mode, well blocking mode and oil production mode in sequence, and supports the cyclic use of wave code configuration.

[0034] The flow meter 16 is threadedly connected to the one-way valve 15; the one-way valve 15 is threadedly connected to the air nozzle assembly 6; the air nozzle assembly 6 is threadedly connected to the special air nozzle installation channel of the lower joint 11; the main control board battery assembly 5, the hole back pressure detection 7, the external pressure detection 8, the internal pressure detection unit 9, the main control board assembly 13 and the special channel are threadedly connected to the lower joint 11; the power battery assembly 4 is threadedly connected to the lower joint 11; the main control board battery assembly 5 is threadedly connected to the hole back pressure detection 7; the central flow tube 3 is inserted in the flow hole of the lower joint 11; the outer casing 12 is threadedly connected to the lower joint 11; the screen 10 is fixedly connected to the lower joint 11 with screws; the screw ring 2 is buckled onto the upper joint 1, and the flow hole of the upper joint 1 is plugged into the upper end of the central flow tube 3; the upper joint 1 with the screw ring 2 is threadedly connected to the outer casing 12; the plug 14 is threadedly connected to the lower joint 11 to seal the process hole.

[0035] The gas nozzle assembly 6 includes a motor, a gas nozzle valve core 602 and a gas nozzle valve sleeve 601. Figure 5 The gas nozzle 6011 of the gas nozzle valve sleeve 601 is composed of a wedge-shaped opening for adjusting the injection amount of carbon dioxide and a square opening for oil production. The right wedge-shaped opening is the gas injection opening area for accurately adjusting the injection amount of carbon dioxide in each layer, and the left square opening is the oil production opening area for large-scale oil production.

[0036] like Figure 2-Figure 6 The present invention provides a downhole carbon dioxide flooding same-well intelligent injection and production method based on wave code communication, and the specific operation steps include:

[0037] Wave code configuration preset time and gas nozzle working mode 1301, gas injection mode process 1302, well blocking mode process 1303, oil production mode process 1304 and waiting for re-wave code communication process 1305.

[0038] The wave code configuration preset time and the air nozzle working mode 1301 are specifically as follows:

[0039] The ground wave code communication controller sends a wave code communication signal to the intelligent injection and production device in the same well. The internal pressure detection unit 9 of the intelligent injection and production device in the same well detects the wave code signal and transmits it to the main control board component 13. The main control board component 13 analyzes the wave code signal and configures the preset time and gas nozzle working mode according to the signal. The gas nozzle working mode includes gas injection mode, well blocking mode and oil production mode.

[0040] The gas injection mode process 1302 is specifically as follows:

[0041] When the signal indicates the gas injection mode, the main control board assembly 13 sends a control command to the motor of the gas nozzle assembly 6. The motor operates to adjust the gas nozzle valve core 602, causing the gas nozzle valve core 602 to move backward and displace the gas nozzle valve sleeve 601. The gas nozzle 6011 gradually opens. At this time, supercritical carbon dioxide passes through the flow meter 16, pushing open the check valve 15 and entering the gas injection mode. After the gas nozzle 6011 opens, the flow meter 16 detects the flow rate and feeds it back to the main control board assembly 13. The main control board assembly 13 sends a command to the gas nozzle assembly 6 to adjust the flow rate. When the flow rate reaches the required gas injection volume, the motor stops and enters the stable gas injection mode. If the gas injection mode ends, the wellbore mode is entered; if not, gas injection continues.

[0042] The process 1303 of the well blocking mode is as follows:

[0043] When the signal indicates the well-blocking mode, the main control board assembly 13 sends a control command to the motor of the gas nozzle assembly 6. The motor rotates the gas nozzle valve core 602, which moves forward and displaces the gas nozzle valve sleeve 601 until the gas nozzle 6011 is closed, entering the well-blocking mode. The well-blocking mode lasts for a preset time until the well-blocking time expires. In this mode, the supercritical carbon dioxide and crude oil in the formation gradually form a miscible phase, reducing the crude oil's viscosity and causing it to expand in volume, facilitating subsequent crude oil recovery. If the well-blocking mode ends, the oil recovery mode begins; if not, oil recovery continues.

[0044] The oil production mode process 1304 is specifically as follows:

[0045] When the signal is in oil production mode, the main control board assembly 13 sends a control command to the motor of the gas nozzle assembly 6. The motor rotates the gas nozzle valve core 602, which moves backward, creating a large displacement with the gas nozzle valve sleeve 601, until the gas nozzle 6011 is fully opened, entering oil production mode. At this time, the supercritical carbon dioxide and crude oil in the formation have formed a miscible liquid and expanded in volume. Sand and foreign matter are filtered out by the screen 10, and the oil is produced through the gas nozzle valve sleeve 601 and enters the instrument's oil production center flow pipe 3. Formation pressure closes the one-way valve 15, protecting the flow meter 16 from clogging. At this time, the crude oil mixture is transmitted through the center flow pipe 3 to the surface oil production equipment, thus achieving the purpose of oil production. If the oil production mode ends, the system enters the waiting state for re-wave code communication; if not, oil production continues.

[0046] The waiting for re-wave code communication process 1305 is specifically as follows:

[0047] The intelligent injection and production device in the same well is in a working state of waiting for re-wave code communication. If no valid wave code communication is received, it will remain in a waiting state; if a valid wave code communication is received, it will re-enter the wave code configuration preset time and gas nozzle working mode 1301 to prepare for the next new gas injection, well blocking and oil production workflow.

[0048] The method of the present invention reconfigures the preset time to optimize the production system, improves the oil production efficiency according to the on-site working conditions, and re-enters the next gas injection, well blocking and oil production workflow, achieving the purpose of recycling after one trip to the well.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A downhole carbon dioxide flooding same-well intelligent injection and production method based on wave code communication, characterized by: First, the ground wave code communication controller adjusts the gas nozzle to the gas injection mode and deploys gas injection to each layer in the well; after the gas injection time is over, the gas nozzle is adjusted to the well blocking mode, and each layer in the well is blocked according to the preset time; finally, after the well blocking time is over, the gas nozzle is adjusted to the oil production mode, and each layer in the well begins to produce oil. Specifically, the steps include the following: Step S1, wave code configuration preset time and gas nozzle working mode; specifically: the ground wave code communication controller sends a wave code communication signal to the same well intelligent injection and production device, and the same well intelligent injection and production device configures the preset time and the initial working mode of the gas nozzle through the wave code; Step S2, gas injection mode process; Specifically, after receiving the wave code communication signal, the intelligent injection and production device in the same well adjusts the working mode of the gas nozzle to enter the gas injection mode, and allocates gas injection to each layer; Step S3, the well blocking mode process; specifically: after receiving the wave code communication signal, the intelligent injection and production device in the same well adjusts the gas nozzle working mode to enter the well blocking mode, and each layer blocks the well according to the preset time; Step S4, oil production mode process; Specifically, the ground wave code communication controller sends a wave code communication signal to the intelligent injection and production device in the same well. The intelligent injection and production device in the same well adjusts the gas nozzle working mode to enter the oil production mode, and each layer starts to produce oil. Step S5, waiting for the re-wave code communication process; specifically: the intelligent injection and production device in the same well waits for the ground wave code communication controller to re-wave code communication operation. If no valid wave code communication is received from the ground wave code communication controller, it will be in a waiting state; if a valid wave code communication is received, step S1 will be re-executed.

2. The method for downhole carbon dioxide flooding in a same-well intelligent injection-production system based on wave code communication according to claim 1, characterized in that: The ground wave code communication controller includes a data and instruction main control unit; the same-well intelligent injection and production device includes a main control board component and a gas nozzle component. The data and instruction main control unit sends a wave code communication signal to the main control board component, and the main control board component sends a control instruction to the gas nozzle component and controls it to perform gas injection, well blocking and oil production.

3. The method for downhole carbon dioxide flooding in a same-well intelligent injection-production system based on wave code communication according to claim 2, characterized in that: During gas injection, the motor of the gas nozzle assembly adjusts the gas nozzle valve core to move backward to generate displacement with the gas nozzle valve sleeve, and the gas nozzle gradually opens. At this time, the supercritical carbon dioxide pushes open the one-way valve to enter the gas injection mode.

4. The method for downhole carbon dioxide flooding in a same-well intelligent injection-production system based on wave code communication according to claim 2, characterized in that: When the well is blocked, the motor of the gas nozzle assembly adjusts the gas nozzle valve core to move forward and generate displacement with the gas nozzle valve sleeve until the gas nozzle is closed, entering the well blocking mode.

5. The method for downhole carbon dioxide flooding and same-well intelligent injection and production based on wave code communication according to claim 2, characterized in that: During oil production, the motor of the air nozzle assembly adjusts the air nozzle valve core to move backward and generate displacement with the air nozzle valve sleeve until the air nozzle is fully opened, entering the oil production mode.

6. A downhole carbon dioxide flooding same-well intelligent injection-production method based on wave code communication according to any one of claims 1 to 5, characterized in that: The gas nozzle is composed of a wedge-shaped opening for adjusting the injection amount of carbon dioxide and a square opening for oil production.

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