Oilfield carbon dioxide flooding water gas co-piping metering regulation injection system and method

Abstract

The present application belongs to the field of oil and natural gas development, and discloses a kind of oil field carbon dioxide flooding water gas same pipe metering regulation injection system and method, water injection distributor and CO2 injection distributor are connected with fluid identification pressure detection intercommunicator A, fluid identification pressure detection intercommunicator B, fluid identification pressure detection intercommunicator C simultaneously through pipeline and connect into main pipeline, fluid selection identification valve, multi-medium flowmeter, check valve, vent valve, remote control regulating valve and gate valve are sequentially arranged between main pipeline and water gas alternate injection wellhead, fluid selection identification valve, remote control rotating valve core, high-pressure electromagnetic switch valve A, high-pressure electromagnetic switch valve B, multi-medium flowmeter and remote control regulating valve are connected with display and control controller respectively by signal transmission and control cable.Utilizing a set of system same pipe metering, same pipe regulation, simplifies carbon dioxide water gas alternate injection process flow, is convenient for management, simple operation, less investment cost, system structure is compact, reduces process layout area.

Description

Technical Field

[0001] The present invention belongs to the field of oil and gas development, and relates to a process and method for carbon dioxide storage in oilfield carbon dioxide flooding development and environmental protection projects, and specifically to an oilfield carbon dioxide flooding water and gas co-pipe metering and regulating injection system and method. Background Art

[0002] Currently, CO2 storage and injection technologies for oil recovery are maturing. Various oil fields have begun implementing CO2 recovery projects, demonstrating significant emissions reductions and increased oil recovery. At the same time, the CO2 injection process is exploring a phased, alternating water-gas injection method. This involves injecting a certain amount of CO2 followed by water. This can effectively control underground gas crosstalk and improve oil recovery. This technology is still in the exploratory stage and requires further optimization compared to surface injection processes.

[0003] Currently, the existing alternating CO2 water-gas injection process consists of two separate processes. The water injection system has its flow metered and controlled separately, while the gas injection system also uses separate metering and control. The two systems are then combined at the wellhead and injected into the formation. This requires the simultaneous construction of a water injection room and a gas injection room, along with the processes within the rooms. Summary of the Invention

[0004] To address the challenges of the existing technology, the present invention utilizes a carbon dioxide flooding, water-gas, and simultaneous metered and regulated injection technology. This technology combines the gas and water injection manifolds into a single manifold, enabling simultaneous metered and regulated gas and water injection. This simplifies the metering and regulation process while also saving space in the injection room. This alternating carbon dioxide, water-gas injection system and method is easy to manage, simple to operate, and requires minimal investment. The system features a compact structure, reducing process footprint. The present invention is applicable to alternating carbon dioxide flooding, water-gas injection in most oil fields nationwide.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A carbon dioxide flooding water and gas co-pipe metering and regulating injection system for oil fields, wherein a water injection distributor and a CO2 injection distributor are simultaneously connected to a fluid identification pressure detection connector A, a fluid identification pressure detection connector B, and a fluid identification pressure detection connector C through pipelines and merge into a main pipeline. A fluid selection identification valve, a multi-media flowmeter, a check valve, a vent valve, a remote control regulating valve, and a gate valve are sequentially provided between the main pipeline and the water and gas alternating injection wellhead. The fluid selection identification valve, the remote control rotary valve core, the high-pressure electromagnetic switch valve A, the high-pressure electromagnetic switch valve B, the multi-media flowmeter, and the remote control regulating valve are respectively connected to a display and control controller through signal transmission and control cables.

[0007] Furthermore, a high-pressure electromagnetic switch valve B is provided on the pipeline of the water injection distributor.

[0008] Furthermore, a high-pressure electromagnetic switch valve A is provided on the pipeline of the CO2 injection distributor.

[0009] Furthermore, the fluid selection and identification valve is a three-way valve structure.

[0010] Furthermore, the display and control controller is a single chip microcomputer.

[0011] A method for metering and regulating injection of carbon dioxide flooding water and gas in the same pipe in an oil field comprises the following three steps:

[0012] Step 1: When stopping injection, the rotary valve core is remotely controlled to close, and the fluid identification pressure detection connector A and the fluid identification pressure detection connector B detect whether there is mutual leakage of water and gas. The regulating valve and gate valve are remotely controlled to close, and the high-pressure electromagnetic switch valve A and the high-pressure electromagnetic switch valve B are closed to stop injection into the well;

[0013] Step 2: When switching from the stop injection state to water injection, first open the high-pressure electromagnetic switch valve A to detect the pressure difference at both ends of the water and gas pipeline of the fluid selection identification valve. After balance, the control unit sends a signal to open the remote control rotary valve core to start water injection. At the same time, open the remote control regulating valve to adjust the flow. The multi-media flow meter detects the flow rate, and the flow data is uploaded to the display and controller for comparison. If it exceeds the set value, the display and controller send a signal to adjust the remote control regulating valve until it meets the set flow value, and the entire system starts to inject water;

[0014] Step 3: When switching from water injection to gas injection, the control unit sends a signal to control the remote control to rotate the valve core to inject gas. The multi-media flow meter detects the flow and uploads the flow data to the display and controller for comparison. If the flow exceeds the set value, the display and controller send a signal to adjust the remote control regulating valve until the set flow value is met. The entire system starts to inject gas.

[0015] The beneficial effects of the present invention compared with the prior art are:

[0016] This invention optimizes the alternating water-gas injection process in oilfield carbon dioxide injection systems by combining two separate metering and control systems into a single-pipe injection process system, achieving metered and regulated water-gas injection through the same pipe. This system combines the single-well gas injection pipeline and the single-well water injection pipeline into a single manifold. This streamlines the alternating carbon dioxide-water-gas injection process, facilitating management, simplifying operation, reducing investment costs, and creating a compact system structure that reduces process footprint. This invention is applicable to alternating water-gas injection in oilfields nationwide. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the fluid selection identification valve stop injection stage;

[0018] Figure 2This is a schematic diagram of the water injection stage of the fluid selection identification valve;

[0019] Figure 3 This is a schematic diagram of the fluid selection identification valve during the gas injection phase;

[0020] Figure 4 This is a schematic diagram of a carbon dioxide flooding water and gas co-pipe metering and regulating injection system;

[0021] Figure 5 This is the principle diagram of the fluid selection identification valve.

[0022] 1- Fluid selection identification valve, 2- Pipeline, 3- Fluid identification pressure detection connector A, 4- Fluid identification pressure detection connector B, 5- Fluid identification pressure detection connector C, 6- Remote control rotary valve core, 7- Pressure balance pipe, 8- Signal transmission and control cable, 9- High-pressure electromagnetic switch valve A, 10- High-pressure electromagnetic switch valve B, 11- Multi-media flowmeter, 12- Remote control regulating valve, 13- Flange, 14- Display and controller, 15- Check valve, 16- Vent valve, 17- Gate valve, 18- Water injection distributor, 19- CO2 injection distributor. DETAILED DESCRIPTION

[0023] The present invention is described in detail below by specific examples, but the scope of protection of the present invention is not limited. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0024] Example 1

[0025] Step 1: When stopping betting:

[0026] When injection is stopped, the rotary valve core 6 is remotely controlled to close, and the fluid identification pressure detection connector A3 and the fluid identification pressure detection connector B4 detect whether water and gas are mutually intermingled. The regulating valve 12 is remotely controlled to close, the gate valve 17 is closed, and the high-pressure electromagnetic switch valve A9 and the high-pressure electromagnetic switch valve B10 are closed, and injection into the well is stopped.

[0027] Step 2: When filling water:

[0028] When switching from the stop injection state to the water injection state, first open the high-pressure electromagnetic switch valve A9 to detect the pressure difference at both ends of the water and gas pipeline of the fluid selection identification valve 1. After balance, the control unit sends a signal to open the remote control rotary valve core 6 to start water injection. At the same time, open the remote control regulating valve 12 to adjust the flow. The multi-media flow meter 11 detects the flow data, and the flow data is uploaded to the display and controller 14 for comparison. If it exceeds the set value, the display and controller 14 send a signal to adjust the remote control regulating valve 12 until it meets the set flow value, and the entire system starts to inject water.

[0029] Step 3: When injecting gas:

[0030] When the water injection state is changed to gas injection, the control unit sends a signal to control the remote control rotary valve core 6 to inject gas, which is detected by the multi-media flow meter 11. The flow data is uploaded to the display and controller 14 for comparison. If it exceeds the set value, the display and controller 14 sends a signal to adjust the remote control regulating valve 12 until it meets the set flow value, and the entire system starts to inject gas.

[0031] Example 2

[0032] ① According to the actual situation on site in Jilin Oilfield, the operating pressure is 25MPa, the CO2 injection temperature is -40 to 30°C, and the pipeline uses seamless steel pipe 316L. When injection is stopped, the fluid selection identification valve 1 is closed and the system does not operate. When CO2 is injected, the gas injection pipeline is opened, the CO2 flow data is uploaded, and the fluid selection identification valve 1 is remotely controlled to control the injection pressure. When water is injected, the water injection pipeline is opened, the water injection flow data is uploaded, and the fluid selection identification valve 1 is remotely controlled to control the injection pressure. The overall process is simple to operate and easy to manage.

[0033] ② The water injection side of the fluid selection identification valve 1 is always in a conductive state, and the gas injection side is always in a non-conductive state. If the state changes, it means that carbon dioxide and water have been mixed. The alarm is activated and emergency treatment is carried out. It can also be used to identify whether the system pipeline is leaking.

[0034] ③ The operating conditions of alternating carbon dioxide and water-gas injection in oil fields are diverse and complex. To prevent gas crossflow, the water or gas pipeline is shut down through an intelligent identification system to effectively control the large-scale water-gas intersection during water-gas conversion; check valves 15, stop valves, and gate valves 17 are set to prevent water and gas from flowing back into the ground system at the wellhead during water-gas alternation.

[0035] The above-described embodiments are only preferred embodiments of the present invention, and are not intended to be all feasible embodiments of the present invention. Any obvious modifications made by a person skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. An oilfield carbon dioxide flooding water and gas injection system with metering and regulation, characterized by: The water injection distributor (18) and the CO2 injection distributor (19) are simultaneously connected to the fluid identification pressure detection connector A (3), the fluid identification pressure detection connector B (4), and the fluid identification pressure detection connector C (5) through the pipeline (2) and then merged into the main pipeline. A fluid selection identification valve (1), a multi-media flow meter (11), a check valve (15), a vent valve (16), a remote control regulating valve (12), and a gate valve (17) are sequentially provided between the main pipeline and the water and gas alternating injection wellhead. The fluid selection identification valve (1), the remote control rotary valve core (6), the high-pressure electromagnetic switch valve A (9), the high-pressure electromagnetic switch valve B (10), the multi-media flow meter (11), and the remote control regulating valve (12) are respectively connected to the display and controller (14) through the signal transmission and control cable (8).

2. The oilfield carbon dioxide flooding water and gas co-pipe metering and regulating injection system according to claim 1, characterized in that: A high-pressure electromagnetic switch valve B (10) is provided on the pipeline of the water injection distributor (18).

3. The oilfield carbon dioxide flooding water and gas co-pipe metering and regulating injection system according to claim 1, characterized in that: A high-pressure electromagnetic switch valve A (9) is provided on the pipeline of the CO2 injection distributor (19).

4. The oilfield carbon dioxide flooding water and gas co-pipe metering and regulating injection system according to claim 1, characterized in that: The fluid selection and identification valve (1) is a three-way valve structure.

5. The oilfield carbon dioxide flooding water and gas co-pipe metering and regulating injection system according to claim 1, characterized in that: The display and controller (14) is a single chip microcomputer.

6. A method for metering and regulating injection of carbon dioxide flooding water and gas in the same pipe in an oil field, characterized by: Using the injection system according to any one of claims 1 to 5 comprises the following three steps: Step 1: When stopping injection, the remote-controlled rotary valve core (6) is closed, and the fluid identification pressure detection connector A (3) and the fluid identification pressure detection connector B (4) detect whether water and gas are mutually intermingled, and the remote-controlled regulating valve (12) is closed, the gate valve (17) is closed, the high-pressure electromagnetic switch valve A (9) and the high-pressure electromagnetic switch valve B (10) are closed, and injection into the well is stopped; Step 2: When switching from the stop injection state to the water injection state, first open the high-pressure electromagnetic switch valve B (10) to detect the pressure difference between the two ends of the water and gas pipeline of the fluid selection identification valve (1). After the balance is achieved, the control unit sends a signal to open the remote control rotary valve core (6) to start water injection. At the same time, the remote control regulating valve (12) is opened to adjust the flow rate. The flow rate is detected by the multi-media flow meter (11). The flow rate data is uploaded to the display and controller (14) for comparison. If the flow rate exceeds the set value, the display and controller (14) send a signal to adjust the remote control regulating valve (12) until the set flow rate value is met. The whole system starts to inject water. Step 3: When the water injection state is changed to gas injection, the control unit sends a signal to control the remote control rotary valve core (6) to inject gas, which is detected by the multi-media flow meter (11). The flow data is uploaded to the display and controller (14) for comparison. If the flow exceeds the set value, the display and controller (14) sends a signal to adjust the remote control regulating valve (12) until the set flow value is met, and the entire system starts to inject gas.

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