Continuous high-throughput nanobubble water production system and method for reservoir development

Abstract

The present application belongs to the field of nano-bubble water preparation, and relates to a continuous high-throughput nano-bubble water preparation system and method for oil reservoir development, aiming to solve the problems of low efficiency, small displacement and difficulty in meeting the large-scale continuous operation demand of oil fields in the prior art. The present application comprises a liquid treatment module, a gas generation module, a nano-bubble water series concentration unit and a nano-bubble water injection module. The nano-bubble water series concentration unit is composed of at least two nano-bubble water preparation modules connected in series. An internal circulation preparation circuit is formed by a circulating pump and parallel nano-bubble nozzles inside each preparation module; based on the principle of communicating vessels, the nano-bubble water prepared by the previous module automatically flows into the next module, realizing the step-by-step increase of the nano-bubble concentration. The present application can continuously and efficiently prepare high-concentration and large-displacement nano-bubble water, and the system is modularized, compact in structure, strong in adaptability, low in operation and maintenance cost, and meets the demand of oil field site complex environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of nanobubble water preparation, and particularly relates to a continuous high-throughput nanobubble water preparation system and method for oil reservoir development. BACKGROUND

[0002] In the field of oil exploitation, especially for low-permeability and ultra-low-permeability oil reservoirs, the conventional water flooding development method has low oil displacement efficiency, resulting in a large amount of remaining oil remaining in the ground. With the oilfield entering the later stage of development, problems such as water channeling are increasingly prominent, further limiting the sweep volume and recovery efficiency of the conventional water injection technology. Although the chemical flooding and other enhanced oil recovery technologies have remarkable effects, their high costs limit their large-scale application. Therefore, under the current industry background of reducing costs and increasing efficiency, seeking an economic and efficient enhanced oil recovery technology to effectively develop remaining oil and expand the sweep volume has become a key technical problem faced by oilfield development.

[0003] The nanobubble technology has great potential in improving oil recovery due to its relatively low preparation cost, good bubble stability, high interfacial activity, and the ability to effectively improve oil-water flowability. However, existing nanobubble preparation methods, such as Venturi tube method, hydrodynamic cavitation method, and porous membrane method, generally have the technical bottlenecks of low preparation efficiency and small output displacement, which cannot meet the actual operation requirements of high concentration, large displacement, and continuous stable injection in oilfield sites, limiting the popularization and application of nanobubble technology in oil reservoir development. SUMMARY

[0004] To solve the above problems in the prior art, i.e., the technical problems of low efficiency, small displacement, and inability to meet the requirements of high concentration, large displacement, and continuous preparation in oilfield sites in the existing nanobubble preparation method, the application provides a continuous high-throughput nanobubble water preparation system and method for oil reservoir development.

[0005] In a first aspect of the application, a continuous high-throughput nanobubble water preparation system for oil reservoir development is provided, which comprises a liquid treatment module, a gas generation module, a nanobubble water series concentration unit, and a nanobubble water injection module.

[0006] The nanobubble water series concentration unit comprises at least two nanobubble water preparation modules connected in series.

[0007] The liquid treatment module is connected to the first nanobubble water preparation module in series connection and is used to provide preparation water.

[0008] The gas generation module is connected to each nanobubble water preparation module and is used to provide the preparation gas.

[0009] The nano bubble water injection module is connected to the last nano bubble water preparation module in series connection, and is used for standing and pressurized injection of the finally prepared nano bubble water into the oil reservoir.

[0010] Further, the nano bubble water preparation module comprises a nano bubble water tank, a circulating pump and a nano bubble nozzle.

[0011] The inlet of the circulating pump is communicated with the nano bubble water tank, the outlet of the circulating pump is connected with the liquid inlet of the nano bubble nozzle, and the liquid outlet of the nano bubble nozzle is arranged in the nano bubble water tank, so as to form an internal circulation loop for extracting liquid from the nano bubble water tank and injecting the liquid back into the nano bubble water tank through the nano bubble nozzle.

[0012] The nano bubble nozzle further has a gas inlet communicated with the gas generating module, and is used for supplying the nano bubble nozzle with the preparation gas.

[0013] Among the plurality of nano bubble water preparation modules, two adjacent nano bubble water tanks are connected in series and the connection can be controlled to be opened or closed.

[0014] Further, the number of the nano bubble nozzles is at least two, and a parallel nozzle group is formed.

[0015] The outlet of the circulating pump is communicated with the liquid inlet of each nano bubble nozzle in the parallel nozzle group.

[0016] The gas generating module is communicated with the gas inlet of each nano bubble nozzle in the parallel nozzle group.

[0017] And the outlet of each nano bubble nozzle in the parallel nozzle group is arranged in the nano bubble water tank.

[0018] Further, a first liquid level sensor is arranged in the nano bubble water tank.

[0019] The installation height of the first liquid level sensor is higher than the water outlet on the nano bubble water tank; the first liquid level sensor is used for closing the circulating pump when detecting that the liquid level is lower than the installation height of the first liquid level sensor, and starting the circulating pump when detecting that the liquid level reaches or is higher than the installation height of the first liquid level sensor.

[0020] The water outlet is connected with the inlet of the circulating pump.

[0021] Further, the bottom of each nanobubble water tank is provided with a communication port, the communication ports of two adjacent nanobubble water tanks are connected through a communication pipe, realizing the series connection of at least two nanobubble water tanks, and the last nanobubble water tank is communicated with the nanobubble water injection module through the communication pipe, and the communication pipe is provided with an on-off device.

[0022] Further, the liquid treatment module comprises a water storage tank, a filter and a water pump.

[0023] The water outlet of the water storage tank is connected with the inlet of the filter, the outlet of the filter is connected with the inlet of the water pump, and the outlet of the water pump is connected with the nanobubble water tank in the first nanobubble water preparation module.

[0024] Further, the gas generation module comprises a gas generator, a gas flow regulator and a gas flow meter.

[0025] The gas generator is provided with a plurality of gas outlets, and each gas outlet is connected with the nanobubble nozzle through a gas supply pipeline.

[0026] Each gas supply pipeline is sequentially connected with a gas flow regulator for regulating the gas flow and a gas flow meter for monitoring the gas flow.

[0027] Further, the nanobubble water injection module comprises a nanobubble water standing tank and a booster pump.

[0028] The last nanobubble water tank connected in series is connected with the nanobubble water standing tank through a communication pipe, the nanobubble water standing tank is used for standing treatment of the finally prepared nanobubble water, eliminating the micrometer and millimeter level bubbles generated by the nanobubble nozzle, the water outlet of the nanobubble water standing tank is connected with the inlet of the booster pump, and the outlet of the booster pump is connected with the wellhead device.

[0029] The nanobubble water standing tank is further provided with a second liquid level sensor and a third liquid level sensor, the installation height of the second liquid level sensor is lower than that of the third liquid level sensor, for cooperatively controlling the liquid level of the nanobubble water standing tank and driving the start and stop of the liquid treatment module and the booster pump, so as to maintain the continuous and stable operation of the system.

[0030] Further, the gas generator is one or more of a nitrogen generator, a carbon dioxide generator or a flue gas generator.

[0031] The preparation water is deionized water or a solution added with a surfactant.

[0032] In the second aspect of the present application, a continuous high-flux nanobubble water preparation method for oil reservoir development is provided, which uses the system as described in the first aspect, and the method comprises:

[0033] Step S1, after the preparation water is treated by the liquid treatment module, it is transported to the first nanobubble water preparation module connected in series;

[0034] Step S2, in the nanobubble water preparation module, the circulating pump is started to internally circulate the water in the nanobubble water preparation module, at the same time, the preparation gas generated by the gas generation module is introduced into the nanobubble water preparation module, and the nanobubbles are generated in the high-speed vortex inside the nanobubble nozzle by the circulating water and the preparation gas, to obtain the preliminary nanobubble water;

[0035] Step S3, the nanobubble water prepared in the previous nanobubble water preparation module is transported to the next nanobubble water preparation module, and the operation of step S2 is repeated to gradually increase the concentration of nanobubbles in the nanobubble water;

[0036] Step S4, the high-concentration nanobubble water obtained after the last-stage serial concentration is transported to the nanobubble water injection module, and is placed in the static tank to remove the micro and millimeter-sized bubbles, and then is pressurized and injected into the oil reservoir.

[0037] The present application has the following beneficial effects:

[0038] In the present application, by arranging multiple parallel nanobubble nozzles in a single preparation module, the liquid treatment capacity per unit time is improved, and the bottleneck of large-capacity preparation is solved; at the same time, by connecting multiple preparation modules in series, the nanobubble water generated in the previous stage is used as the raw material liquid for the next stage for gradual concentration, and the final concentration of nanobubbles is effectively and controllably improved. This design not only ensures the overall processing flux of the system, but also achieves the high concentration standard required for oil reservoir development through gradient concentration, fundamentally solving the contradiction that the prior art cannot do both.

[0039] After multi-stage concentration, the nanobubble water of the present application inevitably contains some unstable micro or millimeter-sized bubbles, and these large bubbles have limited effect in the reservoir and are easy to merge and fail. Through the static step, the larger bubbles are naturally escaped or broken by buoyancy, so that the nanobubble water is purified once, and the final injection into the oil reservoir is the pure nanobubbles with more uniform particle size and higher stability, which maximizes the oil recovery rate.

[0040] The application can automatically start the water pump to deliver the liquid to the next stage when the liquid level in each stage of the nanobubble water tank reaches the preset height, without manual intervention. The automatic design not only greatly reduces the operation strength and the risk of human error, but more importantly, ensures that the whole process from source water supply, multi-stage enrichment to final injection can be carried out uninterruptedly and stably, fully meets the strict requirements of long-term and continuous injection operation in oilfield site, and ensures the continuity and reliability of production.

[0041] The system of the application adopts modular design, which can be fixed or pry-mounted, is convenient for transportation, rapid installation and flexible deployment, and can adapt to various complex working conditions such as plains, mountains, gobi, deserts and offshore platforms with narrow space range. At the same time, the system allows using low-cost industrial by-product gases such as flue gas as gas source, and can be used with chemical agents such as surfactants, which greatly reduces the operation cost and has significant economic advantage compared with traditional chemical flooding technology, providing a feasible technical path for low-cost and efficient development of low-permeability oil reservoirs. BRIEF DESCRIPTION OF DRAWINGS

[0042] Other features, objects and advantages of the application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings:

[0043] Figure 1 is a structural schematic diagram of a continuous high-flux nanobubble water preparation system for oil reservoir development of the application;

[0044] Figure 2 is a schematic diagram of concentration change of nanobubbles in the nanobubble water tank in series of the continuous high-flux nanobubble water preparation system for oil reservoir development of the application;

[0045] Figure 3 is a nanobubble diagram of the continuous high-flux nanobubble water preparation system for oil reservoir development of the application, which is taken by a Malvern nanoparticle tracking analyzer;

[0046] Figure 4 is a particle size distribution diagram of nanobubbles of the continuous high-flux nanobubble water preparation system for oil reservoir development of the application, which is given by a Malvern nanoparticle tracking analyzer;

[0047] In the diagram: 1. Water storage tank; 2. First valve; 3. Filter; 4. Water pump; 5. First liquid flow meter; 7. Gas flow regulator; 8. Gas generator; 9. Wellhead device; 10. Gas flow meter; 11. Nanobubble water tank; 12. Nanobubble nozzle; 13. First liquid level sensor; 14. Water outlet; 15. Connecting port; 16. Connecting pipe; 17. Nanobubble water settling tank; 21. Second valve; 22. Third valve; 23. Fourth valve; 41. Circulation pump; 42. Booster pump; 51. Second liquid flow meter; 52. Third liquid flow meter; 171. Second liquid level sensor; 172. Third liquid level sensor. Detailed Implementation

[0048] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0049] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0050] like Figures 1-4 As shown, the first embodiment of the present invention provides a continuous high-throughput nanobubble water preparation system for reservoir development, including: a liquid processing module, a gas generation module, a nanobubble water series enrichment unit, and a nanobubble water injection module;

[0051] The nanobubble water series enrichment unit includes at least two nanobubble water preparation modules connected in series; the liquid treatment module is connected to the first nanobubble water preparation module in the series connection and is used to provide preparation water; the gas generation module is connected to each nanobubble water preparation module and is used to provide the preparation gas; the nanobubble water injection module is connected to the last nanobubble water preparation module in the series connection and is used to let the finally prepared nanobubble water stand and inject it into the oil reservoir under pressure.

[0052] Reference Figure 1 The system of this invention employs a modular design, dividing the entire preparation process into four clearly defined parts. The liquid processing module, as the system's source, provides qualified raw water for the preparation process. The gas generation module provides the gas required to generate nanobubbles. The core nanobubble water cascade enrichment unit, by connecting multiple preparation modules in series, achieves a step-by-step amplification of nanobubble concentration. Finally, the nanobubble water injection module processes and transports the finished product, completing the final purpose of injection into the oil reservoir.

[0053] The modular overall architecture makes the system structure compact, the functions of each part are independent and work together, which not only facilitates customized configuration according to the field requirements, but also greatly simplifies the installation, disassembly, transportation and maintenance processes. The system can be a fixed device or an integrated and pry-mounted mobile device on a vehicle, which can flexibly adapt to various complex oilfield operation environments such as plains, mountains, Gobi, deserts and even space-limited offshore platforms, and has low operation and maintenance costs.

[0054] In a preferred embodiment, the nanobubble water preparation module comprises a nanobubble water tank 11, a circulating pump 41, and a primary nanobubble nozzle 12; the inlet of the circulating pump 41 is in communication with the nanobubble water tank 11, the outlet of the circulating pump 41 is connected to the liquid inlet of the nanobubble nozzle 12, and the liquid outlet of the nanobubble nozzle 12 is arranged in the nanobubble water tank 11, thereby forming an internal circulation loop that draws liquid from the nanobubble water tank 11 and injects it back into the nanobubble water tank 11 through the nanobubble nozzle 12;

[0055] The nanobubble nozzle 12 also has a gas inlet in communication with the gas generation module for supplying the nanobubble nozzle 12 with the preparation gas, and among multiple nanobubble water preparation modules, two adjacent nanobubble water tanks 11 are connected in series and the connection can be controlled to be on or off.

[0056] Referring to Figure 1 Specifically, taking the first-stage nanobubble water preparation module in the series unit as an example, this module is the starting unit for nanobubble water preparation and is responsible for converting the treated clean source water into preliminary nanobubble water. The core of this module is a high-efficiency internal circulation enrichment loop. The sidewall of the first nanobubble water tank 11 is provided with a water outlet 14 connected to the inlet of the circulating pump 41 through a pipeline, and the outlet of the circulating pump 41 is connected to the liquid inlet of the primary nanobubble nozzle 12 through a pipeline. The first-stage nanobubble nozzle 12 is fixedly installed on the tank body of the first nanobubble water tank 11, and its jetting outlet faces the inside of the tank.

[0057] Meanwhile, the gas inlet of the first-stage nanobubble nozzle 12 is connected to the gas supply pipeline of the gas generation module. In operation, the circulating pump 41 draws the initial liquid in the nanobubble water tank 11 and pressurizes it to form a high-speed water flow that is pumped into the nanobubble nozzle 12.

[0058] Meanwhile, the gas from the gas generating module is also precisely controlled and enters the nano-bubble nozzle 12. The high-speed water flow and the gas generate high-speed vortex inside the nano-bubble nozzle 12, thereby generating a large number of nanoscale bubbles. The nano-bubble nozzle preferably adopts a large inner diameter design, so that the gas and the liquid are easy to pass through, and has the advantage of not being easy to be blocked during preparation, ensuring long-term stable operation of the system. The water and the gas are continuously circulated in the nano-bubble nozzle 12 and the nano-bubble water tank, and as a result, the concentration of the nano-bubbles in the liquid in the first nano-bubble water tank 11 starts from zero and gradually increases, forming preliminary nano-bubble water with a certain concentration. The nano-bubble water obtained after this preliminary concentration increase will be used as the feed of the next preparation module. Through the subsequent second, third, nth modules in series, the concentration of the nano-bubbles will be further increased on the basis of the previous stage, and finally the preparation of high-concentration nano-bubble water is realized.

[0059] Specifically, when the system is initially started, all the communication channels between the stages are in a closed state. The liquid treatment module first injects water into the first nano-bubble water tank 11, and when the liquid level height exceeds the first liquid level sensor 13, the circulation pump 41 of the first nano-bubble water tank 11 and the gas supply are started, and the preparation of nano-bubble water is started independently. When the concentration of nano-bubbles in it reaches the preset requirement, the communication channel between the first nano-bubble water tank 11 and the second nano-bubble water tank 11 is opened, and the nano-bubble water that has reached the standard flows into the second stage. Subsequently, the second stage module repeats this process: when the liquid level height exceeds the first liquid level sensor 13, the circulation and preparation of the stage are started, and when the concentration reaches the standard, the communication with the third stage is opened. This process is repeated in turn until all the cascade modules of the system are started. This sequential starting mode ensures that each module can start working under optimal conditions, effectively avoids the dilution of the already concentrated liquid by the low-concentration liquid in the initial stage, and guarantees that the system can quickly and stably output the expected high-concentration nano-bubble water.

[0060] In addition, the nano-bubble nozzle 12 can be a single type of nozzle or a combination of mixed nozzles, and the material can be selected as metal or non-metal material according to the corrosion of the gas used and other factors.

[0061] The structure of each nano-bubble water preparation module is the same, and the present application does not repeat it here.

[0062] In a preferred embodiment, the number of nano-bubble nozzles 12 is at least two, forming a parallel nozzle group; wherein the outlet of the circulating pump 41 is in communication with the liquid inlet of each nano-bubble nozzle 12 in the parallel nozzle group; the gas generation module is in communication with the gas inlet of each nano-bubble nozzle 12 in the parallel nozzle group; and the outlet of each nano-bubble nozzle 12 in the parallel nozzle group is arranged in the nano-bubble water tank 11.

[0063] In order to further improve the processing capacity and preparation efficiency of a single preparation module, the number of nano-bubble nozzles in each module can be more than one, but two, three or more nozzles working in parallel to form a nozzle group.

[0064] In this design, the outlet pipe of the circulating pump 41 is branched to connect to the liquid inlet of each parallel nozzle, and similarly, the gas supply pipe is also branched into multiple branches to supply gas to each nozzle. The outlets of all parallel nozzles are arranged inside the same nano-bubble water tank 11. By using a parallel nozzle group, the liquid processing capacity and the total gas-liquid contact area per unit time are greatly increased, which is equivalent to increasing the number of nano-bubble circulation generation, thereby significantly shortening the time required to raise the liquid concentration in the module to the target value, and improving the preparation efficiency of a single stage.

[0065] In a preferred embodiment, in order to realize accurate control and real-time monitoring of the nano-bubble internal circulation enrichment process, key monitoring and adjusting elements are arranged around the circulating pump 41. Specifically, a first pressure gauge 6 is arranged on the circulating pump 41. The first pressure gauge 6 is used to display the pumping pressure in real time, and the operator can determine whether the system is running in the best pressure range. A second liquid flow meter 51 is arranged on the pipeline between the circulating pump 41 and the nano-bubble nozzle 12, i.e. before the high-pressure liquid enters the nano-bubble nozzle 12. The second liquid flow meter 51 can accurately measure the instantaneous flow through the nano-bubble nozzle 12, providing key data for quantifying processing capacity and optimizing process parameters. In addition, a second valve 21 is arranged on the pipeline connecting the circulating pump 41 and the nano-bubble water tank 11. The second valve 21 mainly plays a role in adjusting and maintaining, on the one hand, it can fine-tune the backflow pressure or flow in the circulating pipeline by adjusting its opening degree, on the other hand, it can conveniently close the pipeline to isolate the circulating pump and the nozzle part from the water tank during system maintenance or nozzle replacement. The cooperative configuration of these elements constitutes a complete monitoring and control loop, greatly improving the operation accuracy, stability and maintainability of a single nano-bubble preparation module, thereby ensuring the preparation efficiency and quality of the final product.

[0066] In a preferred embodiment, a first liquid level sensor 13 is further provided inside the nanobubble water tank 11; the installation height of the first liquid level sensor 13 is higher than the water outlet 14 on the nanobubble water tank 11; the first liquid level sensor 13 is used to shut down the circulation pump 41 when it detects that the liquid level is lower than its own installation height; and to start the circulation pump 41 when it detects that the liquid level reaches or exceeds its own installation height.

[0067] The outlet 14 is connected to the inlet of the circulating pump 41;

[0068] Inside each nanobubble water tank 11, at least one first liquid level sensor 13 is installed. The primary purpose of this sensor is to ensure that the nanobubble nozzle 12 is completely submerged in water during operation and that air does not enter the circulation pump 41, thereby ensuring the efficiency of nanobubble generation.

[0069] Specifically, when the liquid level in the first nanobubble water tank 11 falls below the installation height of the first liquid level sensor 13 due to internal circulation and upstream water intake, it indicates that the liquid level is too low and cannot guarantee the effective generation of nanobubbles. The control system will then shut down the circulation pump 41 to protect the equipment. When the liquid level is higher than the first liquid level sensor 13, ensuring that the nanobubble nozzle 12 is in a safe working environment, the circulation pump 41 is allowed to start and begin operation, circulating and preparing nanobubble water within the module.

[0070] This automatic control based on liquid level sensors ensures that the liquid can flow continuously and stably from the previous stage to the next stage, avoiding manual intervention and guaranteeing the continuity and stability of the entire series concentration process.

[0071] In a preferred embodiment, each nanobubble water tank 11 has a connecting port 15 at its bottom. The connecting ports 15 of two adjacent nanobubble water tanks 11 are connected by a connecting pipe 16, thereby achieving a series connection of at least two nanobubble water tanks 11. The last nanobubble water tank 11 is connected to the nanobubble water injection module through the connecting pipe 16, and the connecting pipe 16 is equipped with an on / off device. In this embodiment, the on / off device is preferably a valve.

[0072] like Figure 1 As shown, the bottom of the first nanobubble water tank 11 is provided with a connecting port 15, which is connected to the inlet of the second nanobubble water tank 11 through a connecting pipe 16. Similarly, the second nanobubble water tank 11 is connected in series with the third nanobubble water tank 11 through the same structure.

[0073] Among them, in addition to the bottom of the first nanobubble water tank 11 is provided with a communication port 15, the rest of the nanobubble water tank 11 is provided with 2 communication port 15, one of which is used as an inlet to receive liquid from the previous stage tank, the other is used as an outlet to transport liquid to the next stage tank or the final static tank. For example, one of the bottom communication ports 15 of the second nanobubble water tank 11 receives liquid from the first tank, and the other bottom communication port 15 is connected to the inlet of the third nanobubble water tank 11 through a communication pipe.

[0074] This series structure realized by the bottom communication port and the communication pipe essentially constitutes a communicating vessel system. With the help of the communicating vessel principle, when the liquid level in the nanobubble water static tank 17 is lowered due to the injection operation, the original liquid level balance of the system will be destroyed, and in order to restore the liquid level, the nanobubble water prepared in the previous stage module will automatically flow into and supplement the next stage module. This series structure is the key to realizing the high concentration preparation of nanobubble water.

[0075] The liquid is first subjected to preliminary enrichment in the first nanobubble water tank 11, and after reaching a certain concentration, it is introduced into the second nanobubble water tank 11. In the second tank, the liquid containing a certain concentration of nanobubbles serves as the bottom liquid, and on this basis, the second round of internal circulation enrichment is carried out to further increase the concentration. In this way, the concentration of nanobubbles increases by one level each time the liquid passes through a stage of the series module, and finally a high concentration of nanobubble water that is much higher than that obtained by single-stage preparation is obtained at the outlet of the last stage.

[0076] It should be noted that the above method of realizing inter-stage transportation through the communicating vessel principle is a preferred and specific embodiment of the present embodiment, but it is not the only limitation of the present invention. Those skilled in the art can choose to use a power delivery pump to pump nanobubble water from the previous stage to the next stage according to the actual site layout, system size or pressure demand. Such simple variations and alternative solutions based on the core concept of the present invention should be included within the scope of protection of the present invention.

[0077] As shown in Figure 2 , the trend of increasing nanobubble concentration in the multi-stage series water tank is clearly shown. Similarly, the installation method and position of the nanobubble nozzle 12, the water outlet, and the first liquid level sensor 13 in the second nanobubble water tank 11, the third nanobubble water tank 11, and the nth nanobubble water tank 11 are the same as those in the first nanobubble water tank 11, ensuring the consistency of the structure and function of each stage module.

[0078] In a preferred embodiment, the liquid treatment module comprises a water storage tank 1, a filter 3 and a water pump 4; the water outlet of the water storage tank 1 is connected to the inlet of the filter 3, the outlet of the filter 3 is connected to the inlet of the water pump 4, and the outlet of the water pump 4 is connected to the nanobubble water tank 11 in the first nanobubble water preparation module.

[0079] In particular implementation, the source water is stored in the water storage tank 1, enters the filter 3 after passing through the first valve 2, and is used to filter out suspended solids, silt and other impurities in the water. The filtered clean water enters the water pump 4, is pressurized by the water pump 4, passes through the first liquid flow meter 5 to monitor the flow, and is finally injected into the first nanobubble water tank 11 of the series connection unit. The function of this module is to ensure the water quality entering the core preparation unit, prevent impurities from damaging the precision nanobubble nozzle, and provide stable water source supply for the system.

[0080] As a preferred solution, the liquid in the water storage tank 1 can be deionized water or conventional ionic water to eliminate the potential negative impact of ions in the water on the surface charge and stability of nanobubbles; or it can also be a solution containing a surfactant configured in advance, which can be a cationic, anionic or non-ionic surfactant. Adding a surfactant can not only be adsorbed on the bubble surface to reduce the gas-liquid interfacial tension, thereby increasing the concentration of nanobubbles and prolonging their stability time in water, but also can play a role in reducing the oil-water interfacial tension and changing the rock wettability after being injected into the oil reservoir, and together with nanobubbles, ultimately achieve the purpose of improving the oil recovery.

[0081] In a preferred embodiment, the gas generation module comprises a gas generator 8, a gas flow regulator 7 and a gas flow meter 10; the gas generator 8 is provided with a plurality of gas outlets, each of which is connected to the nanobubble nozzle 12 through a gas supply pipeline; the gas flow regulator 7 for regulating the gas flow and the gas flow meter 10 for monitoring the gas flow are connected in series on each gas supply pipeline.

[0082] This module is responsible for providing gas with controllable types and flow rates for all nanobubble nozzles. The gas generator 8 can be flexibly selected according to the specific needs of reservoir displacement, including but not limited to nitrogen generator, carbon dioxide generator, and other single gas or mixed gas generators. For example, the treated flue gas which is surplus in the oilfield can be directly used as a gas source, thereby reducing the operating cost.

[0083] The gas generated by the gas generator 8 is delivered to each nanobubble water preparation module through independent pipelines. A gas flow regulator 7 and a gas flow meter 10 are installed in sequence on each gas supply pipeline. The gas flow regulator 7 is used to accurately set the amount of gas injected into each module, and the gas flow meter 10 is used to monitor and feedback the gas flow in real time, so as to realize accurate control of the gas-liquid ratio and ensure the stability and efficiency of the nanobubble preparation process.

[0084] More specifically, the gas supply pipeline includes a main pipeline and multiple branch pipelines connected in parallel from the main pipeline. The main pipeline is directly connected to the outlet of the gas generator 8, and a gas flow regulator 7 for regulating the total gas flow and a gas flow meter 10 for monitoring the total gas flow are sequentially arranged on the main pipeline. Each branch pipeline connected from the main pipeline is accurately connected to the gas inlet of one nanobubble nozzle 12, responsible for delivering the distributed gas to the corresponding nozzle. This hierarchical gas supply structure of the main pipeline-branch pipeline, combined with accurate regulation on the main pipeline, can ensure stable and uniform gas flow into each nanobubble nozzle, thereby realizing accurate control of the total gas-liquid ratio and the local gas-liquid ratio distributed to each nanobubble nozzle 12, which is crucial for generating nanobubbles with uniform particle size and stable concentration. When preparing nanobubbles of corrosive gases such as carbon dioxide, the entire gas supply pipeline network, including the main pipeline, all branch pipelines, valves, and sealing devices, needs to use corrosion-resistant materials to ensure long-term stable operation of the equipment.

[0085] Among them, a third valve 22 is arranged between the gas generator 8 and the gas flow regulator 7 of each branch, and the on-off function of gas supply can be realized by opening and closing the third valve 22.

[0086] In a preferred embodiment, the nanobubble water injection module includes a nanobubble water standing tank 17 and a booster pump 42. The last nanobubble water tank 11 connected in series is connected to the nanobubble water standing tank 17 through a communication pipe 16. The nanobubble water standing tank 17 is used for standing treatment of the finally prepared nanobubble water. The outlet of the nanobubble water standing tank 17 is connected to the inlet of the booster pump 42, and a fourth valve 23 is arranged on the connecting pipeline. The outlet of the booster pump 42 is connected to the wellhead device 9.

[0087] In this embodiment, when the concentration of nanobubble water in the last nanobubble water tank 11 connected in series reaches the set threshold, the communication pipeline between the nanobubble water standing tank 17 is opened.

[0088] To realize the automatic operation of the module, the nanobubble water static tank 17 is provided with a second liquid level sensor 171 and a third liquid level sensor 172, and the installation height of the second liquid level sensor 171 is lower than that of the third liquid level sensor 172, for cooperatively controlling the liquid level of the nanobubble water static tank 17, and linking the start and stop of the liquid treatment module and the booster pump 42, to maintain the continuous and stable operation of the system.

[0089] The two sensors work cooperatively to provide key liquid level control signals for the automatic operation of the system.

[0090] Specifically, the second liquid level sensor 171 sets the lowest safe working liquid level that allows the nanobubble water to be delivered to the wellhead device 9. When the liquid level in the nanobubble water static tank 17 is lower than the sensor, it indicates that the qualified nanobubble water storage for injection is insufficient, and the control system will prohibit the booster pump 42 from starting or stop it from running, to protect the equipment and ensure the injection quality. Conversely, when the liquid level rises and exceeds the second liquid level sensor 171, the control system allows or directly starts the booster pump 42 to start stable delivery to the wellhead device 9.

[0091] The third liquid level sensor 172 serves as the highest liquid level protection device of the system. Once the liquid level continues to rise and triggers the sensor, it indicates that the generation rate of nanobubble water is greater than the injection rate, and the storage tank will soon be full. At this time, the control system will immediately issue an instruction to stop the water pump 4 in the liquid treatment module, cutting off the water inflow from the source, thereby forcing the preparation system in the previous stage to pause work, effectively preventing liquid overflow and ensuring safety on site.

[0092] On this basis, the start and stop of the water pump 4 are directly controlled by the liquid level of the nanobubble water static tank 17, to realize the automatic balancing of the whole system: when the liquid level is lower than the second liquid level sensor 171, the water pump 4 is started to supply water to the system; when the liquid level is higher than the third liquid level sensor 172, the water pump 4 is stopped. By accurately matching and adjusting the water supply of the water pump 4 and the injection displacement of the booster pump 42, the system can dynamically stabilize the liquid level of the nanobubble water static tank 17 between the second liquid level sensor 171 and the third liquid level sensor 172, thereby ensuring the continuous, stable and efficient operation of the whole process from preparation to injection without manual intervention.

[0093] In this embodiment, the installation height of the first liquid level sensor 13 can be lower than or equal to that of the second liquid level sensor 171, so that when any nanobubble water tank 11 in the front end stops the circulating pump 41 due to too low liquid level, the liquid level in the nanobubble water static tank 17 will also inevitably drop synchronously, thereby triggering the second liquid level sensor 171 and linking the booster pump 42 of the injection module to stop, forming a global equipment protection.

[0094] In the specific operation, the high-concentration nanobubble water prepared through multi-stage series concentration is pumped from the last nanobubble water tank 11 into the nanobubble water standing tank 17. In the standing tank, the nanobubble water is allowed to stand for a period of time. Since the buoyancy of the larger bubbles, such as micro-bubbles and millimeter-sized bubbles, in water is much greater than that of the nanobubbles, they will quickly float up and escape the liquid surface during this process, while the stable nanobubbles will remain in the water. This maturation or purification process ensures that the liquid injected into the oil reservoir mainly contains stable nanobubbles, avoiding the merging or failure of large bubbles in the formation and ensuring the oil displacement effect.

[0095] The high-concentration nanobubble water formed by the system has good stability and can exist stably for at least half a month at normal temperature and pressure, meeting the time requirements for injection at the oilfield site. The booster pump 42 increases the pressure to meet the requirements of the formation injection pressure, and finally the high-concentration nanobubble water is continuously and stably injected into the target oil reservoir through the wellhead device 9. The flow rate of the entire system, including the processing flow rate of the nanobubble nozzle and the final injection flow rate, can be selected and adjusted according to the actual demand of the injection well, for example, from 10 tons / day, 100 tons / day to 5000 tons / day, without limiting the minimum or maximum flow rate, and has great flexibility.

[0096] In this embodiment, a third liquid flow meter 52 is provided on the pipeline between the booster pump 42 and the wellhead device 9, which is used to monitor and feedback the instantaneous flow rate and cumulative flow rate of the high-concentration nanobubble water injected into the oil reservoir in real time. More specifically, the data collected by the third liquid flow meter 52 is the direct basis for determining whether the system meets the requirements of the oilfield injection well. The operating personnel or the control system can accurately adjust the working conditions of the booster pump 42 or the water supply amount of the upstream water pump 4 according to the feedback to ensure the stability and accuracy of the injection flow rate.

[0097] The injection flow rate data monitored by the third liquid flow meter 52, together with the water supply flow rate of the water pump 4, constitutes the key parameters for calculating the water balance of the system. By comparing the water supply amount monitored by the first liquid flow meter 5 with the injection amount monitored by the third liquid flow meter 52, the start-stop and operation frequency of the water pump 4 and the booster pump 42 can be more accurately controlled, so that the liquid level of the nanobubble water standing tank 17 can be dynamically stabilized between the second liquid level sensor 171 and the third liquid level sensor 172 more intelligently, and the continuous and stable operation of the entire process is ensured.

[0098] In one specific embodiment, in order to accurately monitor and control the delivery process of the liquid between the different levels of the nanobubble water tank, a second pressure gauge 61 is arranged on the booster pump 42 responsible for the inter-stage delivery, providing an intuitive status indication for the operator. By observing the reading of the second pressure gauge 61, it can be immediately confirmed whether the booster pump 42 has been started and is working normally, and whether its output pressure has reached the process set requirements.

[0099] The nanobubbles prepared by the present application, with reference to Figure 3 and Figure 4 After three repeated measurements, the nanobubble particle size distribution shows that the particle size of the nanobubbles is mainly concentrated between 50-200 nm, the average particle size is 84 nm, the concentration of nanobubbles with a peak particle size of 79 nm reaches 1.48×10 7 / milliliter, the concentration of nanobubbles with a peak particle size of 115 nm reaches 0.54×10 7 / milliliter, the concentration of nanobubbles with a peak particle size of 174 nm reaches 0.03×10 7 / milliliter, and the number of nanobubbles with a particle size greater than 200 nm is too small to be ignored.

[0100] The second embodiment of the present application proposes a continuous high-throughput nanobubble water preparation method for oil reservoir development, which uses the system as described above, and the method comprises:

[0101] Step S1, after the preparation water is treated by the liquid treatment module, it is delivered to the first nanobubble water preparation module connected in series;

[0102] Step S2, in the nanobubble water preparation module, the circulating pump is started to circulate the water in the nanobubble water preparation module, at the same time, the preparation gas generated by the gas generation module is introduced into the nanobubble water preparation module, and the high-speed water flow and the gas generate high-speed vortex inside the nanobubble nozzle to obtain the preliminary nanobubble water;

[0103] Step S3, the nanobubble water prepared in the previous nanobubble water preparation module is delivered to the next nanobubble water preparation module, and the operation of step S2 is repeated to gradually increase the concentration of nanobubbles in the nanobubble water;

[0104] Step S4, the high-concentration nanobubble water obtained after the last-stage series concentration is delivered to the nanobubble water injection module, and is placed in the standing tank to remove the micro-sized and millimeter-sized large bubbles, and is injected into the oil reservoir after being pressurized.

[0105] The method systematically summarizes the workflow of the application. First, the source water is pumped into the first preparation module after being filtered and purified. Then, in each preparation module, nanobubble concentration is continuously increased by internal circulation and gas-liquid high-speed vortex. When the liquid level reaches the set height, the liquid is automatically transported to the next module for higher-level concentration. This process is repeated until the last module. Finally, the nanobubble water that meets the final concentration requirement is sent to the standing tank for purification and stabilization treatment, and then injected into the oil well through the booster pump. The entire method realizes the automation and continuity of the whole process from source water to high-concentration nanobubble water injection, combines the core ideas of parallel efficiency improvement and series concentration, and can provide stable, reliable, and large-volume high-quality nanobubble water for oilfield sites.

[0106] The terms "first", "second", and the like are used to distinguish similar objects, not to describe or indicate a particular order or sequence.

[0107] The term "comprising" or any other similar term is intended to encompass non-exclusive inclusion, so that a process, method, article, or device / apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or inherent to the process, method, article, or device / apparatus.

[0108] So far, the technical solutions of the application have been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to related technical features without departing from the principles of the application, and the technical solutions after the changes or replacements will fall within the protection scope of the application.

Claims

1. A continuous high-throughput nanobubble water production system for reservoir development, characterized by, The application relates to a nano-bubble water injection system for oil reservoirs. The system comprises a liquid treatment module, a gas generation module, a nano-bubble water series concentration unit and a nano-bubble water injection module. The nano-bubble water series concentration unit comprises at least two nano-bubble water preparation modules connected in series. The liquid treatment module is connected to the first nano-bubble water preparation module in series connection and is used for providing preparation water. The gas generation module is connected to each nano-bubble water preparation module and is used for providing preparation gas. The nano-bubble water injection module is connected to the last nano-bubble water preparation module in series connection and is used for standing and pressurizing the finally prepared nano-bubble water and injecting the nano-bubble water into the oil reservoir. The nano-bubble water preparation module comprises a nano-bubble water tank (11), a circulating pump (41) and a nano-bubble nozzle (12). The inlet of the circulating pump (41) is communicated with the nano-bubble water tank (11), the outlet of the circulating pump (41) is connected with the liquid inlet of the nano-bubble nozzle (12), and the liquid outlet of the nano-bubble nozzle (12) is arranged in the nano-bubble water tank (11), so as to form an internal circulation loop for extracting liquid from the nano-bubble water tank (11) and injecting the liquid into the nano-bubble water tank (11) through the nano-bubble nozzle (12). The nano-bubble nozzle (12) further has a gas inlet communicated with the gas generation module and used for supplying the preparation gas to the nano-bubble nozzle (12). In the plurality of nano-bubble water preparation modules, two adjacent nano-bubble water tanks (11) are connected in series and the connection can be controlled. The nano-bubble water injection module comprises a nano-bubble water standing tank (17) and a booster pump (42). The last nano-bubble water tank (11) in series connection is connected with the nano-bubble water standing tank (17) through a communication pipe (16), the nano-bubble water standing tank (17) is used for standing the finally prepared nano-bubble water and eliminating the micron and millimeter level bubbles generated by the nano-bubble nozzle (12), the water outlet of the nano-bubble water standing tank (17) is connected with the inlet of the booster pump (42), and the outlet of the booster pump (42) is connected with a wellhead device (9). The nano-bubble water standing tank (17) is further provided with a second liquid level sensor (171) and a third liquid level sensor (172), the installation height of the second liquid level sensor (171) is lower than that of the third liquid level sensor (172), the liquid level of the nano-bubble water standing tank (17) is controlled in cooperation, the liquid treatment module and the booster pump (42) are started and stopped in linkage, and the system is continuously and stably operated.

2. The continuous high-throughput nanobubble water production system for oil reservoir development according to claim 1, characterized in that, The number of the nano-bubble nozzles (12) is at least two, and the parallel nozzle group is formed. The outlet of the circulating pump (41) is communicated with the liquid inlet of each nano-bubble nozzle (12) in the parallel nozzle group. The gas generation module is communicated with the gas inlet of each nano-bubble nozzle (12) in the parallel nozzle group. Furthermore, the outlet of each nanobubble nozzle (12) in the parallel nozzle group is located inside the nanobubble water tank (11).

3. The continuous high-throughput nanobubble water production system for oil reservoir development according to claim 1 or 2, characterized in that, The nanobubble water tank (11) is also equipped with a first liquid level sensor (13). The first liquid level sensor (13) is installed at a height higher than the outlet (14) on the nanobubble water tank (11); the first liquid level sensor (13) is used to shut down the circulation pump (41) when it detects that the liquid level is lower than its own installation height; and to start the circulation pump (41) when it detects that the liquid level reaches or exceeds its own installation height. The outlet (14) is connected to the inlet of the circulating pump (41).

4. The continuous high-throughput nanobubble water production system for oilfield development according to claim 1, characterized in that, Each nano bubble water tank (11) has a connecting port (15) at its bottom. The connecting ports (15) of two adjacent nano bubble water tanks (11) are connected by a connecting pipe (16) to realize the series connection of at least two nano bubble water tanks (11). The last nano bubble water tank (11) is connected to the nano bubble water injection module through the connecting pipe (16). The connecting pipe (16) is equipped with an on / off device.

5. The continuous high-throughput nanobubble water production system for oilfield development according to claim 1, characterized in that, The liquid processing module includes a water storage tank (1), a filter (3) and a water pump (4); The outlet of the water storage tank (1) is connected to the inlet of the filter (3), the outlet of the filter (3) is connected to the inlet of the water pump (4), and the outlet of the water pump (4) is connected to the nano bubble water tank (11) in the first nano bubble water preparation module.

6. The continuous high-throughput nanobubble water production system for oilfield development according to claim 1, characterized in that, The gas generating module includes a gas generator (8), a gas flow regulator (7), and a gas flow meter (10). The gas generator (8) is provided with multiple gas outlets, and each gas outlet is connected to the nanobubble nozzle (12) through a gas supply pipeline; Each of the gas supply pipelines is connected in series with a gas flow regulator (7) for adjusting the gas flow rate and a gas flow meter (10) for monitoring the gas flow rate.

7. The continuous high-throughput nanobubble water production system for oilfield development according to claim 6, characterized in that, The gas generator (8) is one or more of a nitrogen generator, a carbon dioxide generator, or a flue gas generator; The water used in the preparation is deionized water or a solution with added surfactants.

8. A continuous high-throughput nanobubble water production method for reservoir development, characterized by, The method, employing the system as described in any one of claims 1-7, comprises: Step S1: The water used for preparation is processed by the liquid processing module and then transported to the first nanobubble water preparation module connected in series. Step S2: In the nanobubble water preparation module, the circulation pump is started to circulate the water inside the nanobubble water preparation module. At the same time, the preparation gas generated by the gas generation module is introduced into the nanobubble water preparation module and generates nanobubbles by high-speed vortex with the circulating water inside the nanobubble nozzle, thus obtaining preliminary nanobubble water. Step S3: The nanobubble water prepared in the previous nanobubble water preparation module is transferred to the next nanobubble water preparation module, and the operation of step S2 is repeated to gradually increase the concentration of nanobubbles in the nanobubble water. Step S4, the high-concentration nanobubble water obtained after the last stage of series concentration is transported to a nanobubble water injection module, and is allowed to stand in a standing tank to remove micro- and millimeter-sized bubbles, and is then injected into an oil reservoir under pressure.

Images