Indoor preparation device of environment-friendly CO2 micro-foam fluid and application of indoor preparation device in improvement of CO2 capture efficiency of capillary tube of sandstone saline water layer

Abstract

The invention belongs to the technical field of CO2 geological sequestration, and discloses an indoor preparation device of environment-friendly CO2 micro-foam fluid and application of the indoor preparation device to improvement of CO2 capture efficiency of sandstone saline water layer capillary tubes. According to the device, a CO2 gas cylinder, a gas booster pump and a gas flow control meter form a gas injection passage; the water source, the constant-flux pump and the piston container form a liquid injection passage; the gas injection passage and the liquid injection passage which are connected in parallel are converged in the high-pressure-resistant high-speed stirring container; the rear part of the high-pressure-resistant high-speed stirring container is sequentially connected with a multi-stage shearing device, a rock core holder, a two-dimensional high-pressure visual observation cabin, a back-pressure valve and a liquid receiving measuring cylinder; the liquid receiving measuring cylinder is arranged on a tray of a precise electronic balance; mixed fluid which is uniformly stirred at a high speed by the high-pressure-resistant high-speed stirring container sequentially flows to the multi-stage shearing device, the core holder, the two-dimensional high-pressure visual observation cabin, the back-pressure valve and the liquid receiving measuring cylinder. According to the method, the capillary sealing efficiency of the salt water layer on CO2 can be improved, and the sealing safety of CO2 in the salt water layer is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of CO2 geological storage, and specifically relates to an indoor preparation device of an environmentally friendly CO2 micro-foam fluid and its application in improving the efficiency of capillary CO2 capture in sandstone saline water layers. Background Art

[0002] Deep saline aquifers are the most widely distributed geological bodies in China with the greatest potential for CO2 storage. For saline aquifer CO2 storage projects, the CO2 storage mechanisms in saline aquifers can be divided into structural capture, capillary capture, dissolution capture and mineralization capture. Among them, capillary capture is safer than structural capture, and in terms of occurrence time, capillary capture occurs in a shorter time than dissolution capture and structural capture. In addition, the increase in the capillary capture efficiency of CO2 in the seepage channel is conducive to enhancing the flow resistance of CO2 in the dominant seepage channel and promoting the flow of CO2 to low permeability areas with high flow resistance. At the same time, it plays a role in expanding the scope of CO2 in the saline aquifer.

[0003] In view of the similarities between the engineering process of CO2 storage in saline aquifers and CO2 enhanced oil and gas recovery, there are reports on the use of foam flooding technology to improve the efficiency of CO2 storage in saline aquifers. However, due to the public welfare nature of the CO2 storage project in saline aquifers, the application of high-concentration foaming and foam-stabilizing colloid materials will inevitably increase the cost of the CO2 storage project in saline aquifers. At the same time, ordinary foam fluids that have not been treated with special injection processes have bubble groups with larger particle sizes, and these bubble groups need to overcome higher capillary resistance to enter small-sized pores. Considering that most of the saline aquifers suitable for CO2 storage in China are located in continental sedimentary basins, these saline aquifers generally have the characteristics of low porosity and low permeability. For the above reasons, it is difficult for ordinary foam flooding technology to be promoted industrially in improving the capillary capture efficiency of CO2 in saline aquifers. In addition, since ordinary foam flooding technology is derived from enhanced oil recovery technology, the impact of the above-mentioned agents on the ecological and environmental toxicity has not been considered in the process of screening foaming agents, foam stabilizers and other agents. In the process of storing CO2 in saline aquifers, it is necessary to consider the impact of the used agents on the toxicity of the saline aquifer and its surrounding water bodies, which is also a point that has been neglected in previous studies.

[0004] In recent years, with the promotion of nano- and micro-bubble technology in municipal projects such as industrial wastewater treatment, aquaculture, and river management, there have also been practical applications of this technology in drilling fluids and enhanced oil recovery. The smaller particle size of nano- and micro-bubbles means that they do not need to overcome a high capillary entry pressure threshold when entering some small-sized pores. While improving the injection capacity of CO2-containing fluids, it also expands the range of CO2 in these high capillary resistance areas. Although the nano- and micro-bubbles have a certain degree of stability because the nano- and micro-bubbles have the same charge on the surface, there is a certain strength of Coulomb repulsion between bubbles, but for some saltwater layers with high temperature and mineralization, the stability of nano- and micro-bubbles still faces huge challenges: under high temperature, with the strengthening of Brownian motion, adjacent bubbles are very likely to coalesce; in a saltwater environment with high mineralization, the surface charge of the bubble liquid film is easily neutralized by counterions, resulting in a decrease or even disappearance of the Coulomb repulsion between bubbles, which also leads to bubble coalescence. Summary of the invention

[0005] The purpose of the present invention is to provide an indoor preparation device for an environmentally friendly CO2 micro-foam fluid and its application in improving the efficiency of CO2 capture by capillary tubes in sandstone saline water layers. On the basis that micron bubbles have a certain degree of self-stability, a low dose of green foaming material is added to the water phase to effectively improve the stability of microbubbles. While reducing the cost of CO2 storage, the scope of CO2 in saline water layers and the efficiency of capillary tube capture are expanded and improved, and the safety of CO2 storage in saline water layers is enhanced.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical measures:

[0007] An indoor preparation device for an environmentally friendly CO2 micro-foam fluid, comprising:

[0008] The gas injection passage is composed of a CO2 gas cylinder, a gas booster pump and a gas flow controller; the liquid injection passage is composed of a water source, a horizontal flow pump and a piston container; the gas injection passage and the liquid injection passage connected in parallel are merged into a high-pressure high-speed stirring container;

[0009] The rear part of the high-pressure resistant high-speed stirring container is connected in sequence to a multi-stage shearing device, a core holder, a two-dimensional high-pressure visual observation cabin, a back-pressure valve and a liquid-receiving measuring cylinder, and the liquid-receiving measuring cylinder is placed on the tray of a precision electronic balance; the mixed fluid after being uniformly stirred at high speed by the high-pressure resistant high-speed stirring container flows to the multi-stage shearing device, the core holder, the two-dimensional high-pressure visual observation cabin, the back-pressure valve and the liquid-receiving measuring cylinder in sequence;

[0010] The back pressure control interface of the back pressure valve is connected to the high-pressure nitrogen cylinder to control the back pressure of the back pressure valve.

[0011] As described above, the present invention uses CO2 and green foaming agent APG to generate CO2 foam fluid in a high-pressure high-speed stirring container, and further shears the CO2 foam fluid into micron-sized bubble groups with a diameter range of 10-50μm through a multi-stage shearing device. By injecting CO2 micro-foam fluid into the sandstone core that has been saturated with the salt water of the simulated target saltwater layer, the advantage of the low capillary entry pressure threshold of microbubbles is utilized to allow a large number of microbubbles to drive the salt water inside the pores of the sandstone core, thereby improving the capillary sealing efficiency of the saltwater layer for CO2 and improving the safety of CO2 sealing in the saltwater layer.

[0012] Optionally, a first pressure sensor is arranged between the multi-stage shearing device and the core holder, and a second pressure sensor is arranged between the core holder and the two-dimensional high-pressure visual observation cabin. The first pressure sensor and the second pressure sensor communicate with the monitoring computer through a pressure and quality data acquisition box, and are respectively used to monitor the displacement pressure of the CO2 foam fluid at the inlet and outlet of the core holder, so as to obtain the dynamic pressure difference change of the CO2 foam during the displacement process in real time;

[0013] The precision electronic balance communicates with the monitoring computer through the pressure and quality data acquisition box, and is used to obtain the dynamic changes of the liquid phase quality in the output fluid in real time by real-time monitoring the changes of the quality data of the precision electronic balance.

[0014] Optionally, an electric stirrer is installed on the top of the high-pressure resistant high-speed stirring container, and the maximum speed of the electric stirrer is 3000 rpm; the high-pressure resistant high-speed stirring container is connected to the stirring paddle speed control box through an electric wire, and the stirring paddle speed control box is adjusted to adjust the stirring paddle speed of the electric stirrer;

[0015] The inlet of the high-pressure resistant high-speed stirring container is located at the top, and the gas injection passage and the liquid injection passage merge at the top inlet of the high-pressure resistant high-speed stirring container; the outlet of the high-pressure resistant high-speed stirring container is located at the bottom, and the foam fluid that has been evenly stirred flows into the multi-stage shearing device through the bottom of the high-pressure resistant high-speed stirring container.

[0016] Optionally, the multi-stage shearing device includes a stainless steel pressure-resistant steel cylinder, a metal screen and porous ceramics, and the metal screen and porous ceramics are arranged from left to right in the stainless steel pressure-resistant steel cylinder, wherein the metal screen is woven from 304 stainless steel, the mesh range of the screen is 1600-2000 mesh, the metal screen has a diameter of 25mm and a length of 30mm; the porous ceramic has an average pore size of 5μm, a diameter of 25mm and a length of 50mm; the CO2 foam fluid flowing out from the outlet of the high-pressure resistant high-speed stirring container flows through the metal screen and porous ceramics in turn, and undergoes step-by-step shearing to achieve the purpose of reducing the particle size of the bubble group.

[0017] Optionally, the two-dimensional high-pressure visual observation chamber is placed under an optical microscope, and the CO2 micro-foam fluid flowing out of the core holder enters the two-dimensional high-pressure visual observation chamber to observe the particle size distribution of the CO2 micro-foam fluid;

[0018] The visualization part of the two-dimensional high-pressure visual observation cabin is a sapphire glass with high-pressure resistance, and its diameter and thickness are 100 and 10 mm respectively; the internal thickness of the two-dimensional high-pressure visual observation cabin is 1 mm; the maximum operating temperature and pressure of the two-dimensional high-pressure visual observation cabin are 130°C and 25MPa respectively.

[0019] Optionally, the working pressure range of the gas flow controller is 0.1-20MPa, and the gas flow rate control range is 0.10-9.99mL / min; the working pressure range of the horizontal flow pump is 0.1-42MPa, and the liquid flow rate control range is 0.001-9.999mL / min.

[0020] Optionally, the middle interface of the core clamp is connected to a confining pressure control pump to achieve the purpose of real-time control of the confining pressure inside the core clamp; the foaming liquid adopts a non-ionic surfactant alkyl polyglycoside APG, and according to the different lengths of the hydrophobic segments of the APG molecules, APG includes APG-0810, APG-10, APG-0812 and APG-0814, and its composition is 0.1-1.0 parts of APG and 100 parts of distilled water.

[0021] Accordingly, the present invention also claims to protect the use of an indoor preparation device of the aforementioned environmentally friendly CO2 micro-foam fluid in improving the efficiency of capillary capture of CO2 in sandstone saline water layers, comprising the following steps:

[0022] 1) Placing the metal screen and porous ceramics inside the stainless steel pressure-resistant steel cylinder to form a multi-stage shearing device;

[0023] 2) Prepare injection fluids, including simulated saline water, foaming liquid phase and CO2 gas;

[0024] 3) Place the sandstone core in a small acrylic sealed box, turn on the vacuum pump to extract the air inside the acrylic sealed box, and then pump simulated salt water into the acrylic sealed box until the simulated salt water level is higher than the top of the core, so that the core is fully saturated with simulated salt water, and the porosity of the sandstone core is measured. ; Then the core was placed in a core holder and the confining pressure of the holder was tracked by a confining pressure control pump, and simulated salt water was injected into the sandstone core at a certain flow rate to measure the permeability K of the sandstone core;

[0025] 4) Use a high-pressure nitrogen cylinder to add back pressure to the back pressure valve to the target pressure;

[0026] 5) Open the valve of the CO2 cylinder, adjust the pressure of the gas booster pump, adjust the gas flow controller and the advection pump to control the volume flow of CO2 and the foaming liquid respectively, and inject the CO2 and the foaming liquid into the high-pressure high-speed stirring container at the same time; and at the same time, turn on the electric stirrer to the maximum speed of 3000 rpm;

[0027] 6) When the internal pressure of the high-pressure resistant high-speed stirring container reaches the system back pressure, the bottom valve of the high-pressure resistant high-speed stirring container is opened, and the CO2 foam fluid stirred evenly inside the high-pressure resistant high-speed stirring container is introduced into the multi-stage shearing device and the core clamp;

[0028] 7) Start the computer monitoring software to monitor the pressure, gas flow and liquid mass changes in each part of the device; calculate the CO2 saturation S of the sandstone core inside the core holder according to the mass conservation method. CO2 ;

[0029] 8) At least respectively change: the type of foaming agent, foaming agent concentration, brine mineralization, CO2-liquid phase volume ratio, CO2-liquid phase injection rate, mixer speed, back pressure valve pressure to adjust the bubble group size distribution of the micro foam, and observe the effect of the micro foam size on the CO2 saturation and CO2 and water distribution of the sandstone core.

[0030] Furthermore, in step 3), the porosity of the sandstone core is measured. And the method of permeability K is:

[0031] The sandstone core was placed in a 105℃ constant temperature box and dried for 48 hours. After drying, the dry weight of the core was measured as m0. Then, the sandstone core was placed in a beaker containing simulated brine, with the brine level higher than the core. The core was placed in a vacuum chamber and the vacuum pump was turned on to allow the core to fully absorb the brine in the beaker. After 48 hours, the core was taken out of the vacuum chamber, the surface moisture of the core was wiped dry, and the wet weight of the core was measured as m1. The porosity of the sandstone core was calculated using formula (1): :

[0032]

[0033] In formula (1), ρ is the simulated brine density, D and L are the core diameter and length, respectively;

[0034] The sandstone core saturated with salt water is placed in a core holder, and the confining pressure of the core holder is adjusted to be always 3 MPa higher than the injection pressure. Then, salt water is injected into the sandstone core at a constant volume flow rate, and the pressure at the front and rear ends of the core holder is monitored. After the pressure difference is stable, the permeability K of the sandstone core is calculated according to formula (2):

[0035]

[0036] In formula (2), Q is the volume flow rate of the simulated brine, with a flow rate range of 0.1-1.0 mL / min; μ is the viscosity of the simulated brine, ΔP is the pressure difference between the front and rear ends of the core holder; and A is the cross-sectional area of ​​the sandstone core.

[0037] Furthermore, in step 7), the CO2 saturation S in the sandstone core is calculated according to formula (3): CO2 :

[0038]

[0039] In formula (3), PV is the pore volume of sandstone core; V in With V out represent the volume of liquid entering the sandstone core and the volume of liquid flowing out of the sandstone core within the experimental time t, respectively; Q1 is the liquid flow rate injected into the core fluid; t is the liquid pumping time; m is the mass added at the precision electronic balance; ρ is the liquid density.

[0040] From the above, when the bubble group with micron size enters the low porosity and low permeability area, it does not need to overcome the high capillary entry pressure threshold, so the micro foam technology has better injectability than the ordinary foam flooding technology. At the same time, by utilizing the small particle size advantage of the micro foam technology, the CO2-containing fluid can enter the small pore area with high seepage resistance while occupying the dominant seepage channel, expanding the scope of the CO2-containing fluid in the saline layer, enhancing the capillary capture efficiency of the CO2-containing fluid in the saline layer, and further enhancing the safety of the saline layer CO2 storage project. In the process of preparing nano and micro bubbles, the present invention adds a green, non-toxic surfactant alkyl polysaccharide APG with excellent stable foam performance, through the stable adsorption of APG molecules on the bubble liquid film to bind the water in the CO2 bubble liquid film, and at the same time rely on the contact between the hydrophilic groups of the APG molecules and the large number of metal ions in the salt water to strengthen the Coulomb repulsion between the liquid films, inhibit the aggregation of CO2 micro bubbles in the high temperature and high mineralization salt water environment, and improve the stability of CO2 micro bubbles in this harsh environment.

[0041] The beneficial effects of the present invention are as follows:

[0042] 1. A high-pressure high-speed stirring container is used to achieve uniform distribution of CO2 in the liquid phase, and a multi-stage shearing device composed of a metal screen and porous ceramics is used to further reduce the size of the bubble group and increase the sweep range of the CO2-containing fluid in the sandstone core;

[0043] 2. With the help of the precise measurement of the horizontal flow pump and the electronic balance, the real-time acquisition of the liquid phase and CO2 saturation inside the sandstone core during the displacement process can be achieved, and the micro-foam size can be adjusted in time according to the changes in the CO2 saturation inside the sandstone core;

[0044] 3. According to the size of microbubbles inside the two-dimensional visual observation cabin, the size of microbubbles can be adjusted in real time by adjusting the flow rate ratio of CO2 and liquid phase, the overall flow rate, the pressure of the back pressure valve, the speed of the mixer and other parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0046] Figure 2 The particle size distribution of CO2 bubble groups in the fluid produced by different displacement methods in Example 1;

[0047] Figure 3 is the CO2 saturation S inside the sandstone core after displacement by different displacement methods in Example 1 CO2 ;

[0048] Figure 4 It is the water phase saturation of the sandstone core after displacement by different displacement methods in Example 1.

[0049] Description of reference numerals:

[0050] 1. CO2 gas cylinder, 2. gas booster pump, 3. gas flow controller, 4. water source, 5. horizontal flow pump, 6. piston container, 7. high-pressure high-speed stirring container, 8. stirring blade speed control box, 9. multi-stage shearing device, 10. metal screen, 11. porous ceramics, 12. core holder, 13. confining pressure control pump, 14. two-dimensional high-pressure visual observation cabin, 15. back pressure valve, 16. precision electronic balance, 17. liquid measuring cylinder, 18. pressure and quality data acquisition box, 19. high-pressure nitrogen gas cylinder, 20. optical microscope, 21. first pressure sensor, 22. monitoring computer; 23. second pressure sensor. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] An indoor preparation device for an environmentally friendly CO2 micro-foam fluid, such as Figure 1As shown, it includes a CO2 gas cylinder 1, a gas booster pump 2, a gas flow controller 3, a water source 4, a horizontal flow pump 5, a piston container 6, a high-pressure high-speed stirring container 7, a stirring blade speed control box 8, a multi-stage shearing device 9, a metal screen 10, a porous ceramic 11, a core holder 12, a confining pressure control pump 13, a two-dimensional high-pressure visual observation cabin 14, a back pressure valve 15, a precision electronic balance 16, a liquid-receiving measuring cylinder 17, a pressure and quality data acquisition box 18, a high-pressure nitrogen gas cylinder 19, an optical microscope 20, a first pressure sensor 21, a monitoring computer 22 and a second pressure sensor 23, wherein:

[0053] The gas injection passage is composed of a CO2 gas cylinder 1, a gas booster pump 2 and a gas flow controller 3;

[0054] The liquid injection passage is composed of a water source 4, a horizontal flow pump 5, and a piston container 6;

[0055] The parallel gas injection passage and liquid injection passage merge into the high-pressure high-speed stirring container 7;

[0056] The rear part of the high-pressure resistant high-speed stirring container 7 is connected in sequence to the multi-stage shearing device 9, the core holder 12, the two-dimensional high-pressure visual observation cabin 14, the back pressure valve 15 and the liquid receiving measuring cylinder 17 through a stainless steel pipeline, and the mixed fluid after being uniformly stirred at high speed by the high-pressure resistant high-speed stirring container 7 flows to the multi-stage shearing device 9, the core holder 12, the two-dimensional high-pressure visual observation cabin 14, the back pressure valve 15 and the liquid receiving measuring cylinder 17 in sequence;

[0057] The liquid receiving measuring cylinder 17 is placed on the tray of the precision electronic balance 16;

[0058] The back pressure control interface of the back pressure valve 15 is connected to the high pressure nitrogen cylinder 19 by a stainless steel pipeline to control the back pressure of the back pressure valve 15 .

[0059] Furthermore, the precision electronic balance 16 communicates with the monitoring computer 22 via the pressure and quality data acquisition box 18, and the dynamic changes in the quality of the liquid phase in the output fluid can be obtained in real time by real-time monitoring of the quality data changes of the precision electronic balance 16.

[0060] Furthermore, a first pressure sensor 21 is arranged between the multi-stage shearing device 9 and the core clamp 12, and a second pressure sensor 23 is arranged between the core clamp 12 and the two-dimensional high-pressure visual observation chamber 14. The first pressure sensor 21 and the second pressure sensor 23 communicate with the monitoring computer 22 through the pressure and quality data acquisition box 18, and are respectively used to monitor the displacement pressure of the CO2 foam fluid at the inlet and outlet of the core clamp 12, so as to obtain the dynamic pressure difference change of the CO2 foam during the displacement process in real time.

[0061] Preferably according to the present invention, the working pressure range of the gas flow controller 3 is 0.1-20MPa, and the gas flow rate control range is 0.10-9.99mL / min; the working pressure range of the horizontal flow pump 5 is 0.1-42MPa, and the liquid flow rate control range is 0.001-9.999mL / min.

[0062] Preferably according to the present invention, the maximum tolerable pressure of the high-pressure resistant high-speed stirring container 7 is 32MPa, the gas injection passage and the liquid injection passage are merged by the top inlet of the high-pressure resistant high-speed stirring container 7, the electric stirrer is installed on the top of the high-pressure resistant high-speed stirring container 7, the stirring paddle blades included in the electric stirrer are propulsion type, the maximum speed of the electric stirrer is 3000rpm, and the outlet of the high-pressure resistant high-speed stirring container 7 is also located at the bottom of the container, and the uniformly stirred foam fluid passes through the bottom of the high-pressure resistant high-speed stirring container and flows into the multi-stage shearing device 9 through a stainless steel pipeline.

[0063] Preferably according to the present invention, the stirring paddle speed control box 8 is connected to the high-pressure resistant high-speed stirring container 7 by electric wires, and the stirring paddle speed control box 8 is adjusted to adjust the stirring paddle speed of the electric stirrer in the high-pressure resistant high-speed stirring container 7; the high-speed stirring and shearing of the stirring paddle inside the high-pressure resistant high-speed stirring container 7 is used to promote the full mixing of CO2 and the foaming liquid to form a CO2 foam fluid with a rich number of bubbles.

[0064] According to the preferred embodiment of the present invention, the multi-stage shearing device 9 is composed of a stainless steel pressure-resistant steel cylinder, a metal screen 10 and a porous ceramic 11, and the metal screen 10 and the porous ceramic 11 are arranged from left to right in the stainless steel pressure-resistant steel cylinder, wherein the metal screen 10 is woven from 304 stainless steel, the mesh number range is 1600-2000 mesh (about 6.5-10 μm), the metal screen 10 has a diameter of 25 mm and a length of 30 mm; the porous ceramic 11 has an average pore size of 5 μm, a diameter of 25 mm and a length of 50 mm. The CO2 foam fluid flowing out of the outlet of the high-pressure high-speed stirring container 7 flows through the metal screen 10 and the porous ceramic 11 in turn, and is sheared step by step to achieve the purpose of reducing the particle size of the bubble group.

[0065] According to the preferred embodiment of the present invention, a stainless steel pipeline is used to connect the confining pressure control pump 13 and the middle interface of the core holder 12 to achieve the purpose of real-time control of the confining pressure inside the core holder 12. In actual use, the confining pressure of the core holder 12 is always controlled to be 2-3 MPa higher than the injection pressure at the injection end of the core holder 12 to prevent the CO2 foam fluid from flowing along the side of the core.

[0066] According to the preferred embodiment of the present invention, the two-dimensional high-pressure visual observation cabin 14 is a cabin body for observing the microscopic morphology of high-pressure fluids, and is composed of an upper and lower flat-welded flange (with an outer diameter and a thickness of 150 mm and 15 mm, respectively). The grooves at the bottom of the upper and lower flanges are installed with a nitrile rubber ring that is resistant to high temperature, resistant to CO2 corrosion and has high sealing performance. A sapphire glass with high pressure resistance (with a diameter and a thickness of 100 mm and 10 mm, respectively) is embedded in the nitrile rubber ring to form the visible part of the observation cabin, and the two pieces of the nitrile rubber ring are installed with high-strength stainless steel bolts. The flanges of the sapphire glasses are connected to form a two-dimensional high-pressure visual observation cabin 14, and the internal height of the high-pressure cabin (i.e., the distance between the two pieces of sapphire glass) is 1 mm; the maximum operating temperature and pressure of the two-dimensional high-pressure visual observation cabin 14 are 130°C and 25 MPa, respectively; the CO2 micro-foam fluid flowing out of the core holder 12 enters the two-dimensional high-pressure visual observation cabin 14 through a stainless steel pipeline, and the particle size distribution of the CO2 micro-foam fluid flowing out of the core holder 12 is observed by placing the two-dimensional high-pressure visual observation cabin 14 under an optical microscope 20.

[0067] In the present invention, the foaming liquid adopts the green and environmentally friendly non-ionic surfactant alkyl polyglycoside APG, which can be divided into APG-0810, APG-10, APG-0812 and APG-0814 according to the length of its hydrophobic segment, and its composition is 0.1-1.0 parts of APG and 100 parts of distilled water. Before the experiment, the prepared foaming liquid of a certain concentration needs to be poured into the piston container 6; after setting the flow rate of the horizontal flow pump 5, the horizontal flow pump 5 absorbs water in the water source 4 at a set rate to push the foaming liquid in the piston container 6 into the high-pressure resistant high-speed stirring container 7; the CO2 foam fluid flowing out of the high-pressure resistant high-speed stirring container 7 enters the multi-stage shearing device 9 through a stainless steel pipeline in order to perform secondary shearing and refinement on the CO2 foam fluid, and further reduce the average particle size of the CO2 bubble group.

[0068] As described above, the present invention injects CO2 and foaming liquid into the high-pressure homogenization container respectively at a set flow rate ratio through the high-pressure gas injection passage and the high-pressure liquid injection passage to achieve the purpose of controlling the volume fraction of CO2 in the micro-foam; then the CO2 and liquid phase are stirred at high speed through the high-pressure high-speed stirring container so that the CO2 and liquid phase are fully mixed. The fully mixed CO2 and liquid phase mixed fluid is then injected into the multi-stage shearing device to perform multi-stage shearing on the bubble group, further reducing the CO2 foam particle size, so that the bubble particle size range reaches 10-50μm.

[0069] An application of the aforementioned device in improving the efficiency of CO2 capture by capillary tubes in sandstone saline layers comprises the following steps:

[0070] 1) placing a metal screen 10 and a porous ceramic 11 inside a stainless steel pressure-resistant steel cylinder to form a multi-stage shearing device 9;

[0071] 2) Prepare injection fluids, including simulated saline water, foaming liquid phase and CO2 gas;

[0072] 3) Place the sandstone core in a small acrylic sealed box. After connecting the vacuum pump to the acrylic sealed box with a stainless steel pipeline, turn on the vacuum pump to extract the air inside the acrylic sealed box, and then pump simulated salt water into the acrylic sealed box until the simulated salt water level is higher than the top of the core, so that the core is fully saturated with simulated salt water, and the porosity of the sandstone core is measured. ; Then, the core is placed in the core holder 12, and the core holder 12 and the confining pressure control pump 13 are connected by a stainless steel pipeline. The confining pressure control pump 13 is used to track the confining pressure of the holder, and simulated salt water is injected into the sandstone core at a certain flow rate to measure the permeability K of the sandstone core;

[0073] 4) Connect the high-pressure nitrogen cylinder 19 and the back-pressure valve 15 with a stainless steel pipeline, and use the high-pressure nitrogen cylinder 19 to add back pressure to the back-pressure valve 15 to the target pressure;

[0074] 5) Connect the CO2 cylinder 1 and the gas booster pump 2 with a stainless steel pipeline, open the valve of the CO2 cylinder 1, adjust the pressure of the gas booster pump 2, adjust the gas flow controller 3 and the advection pump 5 to control the volume flow of CO2 and the foaming liquid respectively, and inject the CO2 and the foaming liquid into the high-pressure high-speed stirring container 7 at the same time; and simultaneously turn on the electric stirrer to a maximum speed of 3000 rpm;

[0075] 6) When the internal pressure of the high-pressure resistant high-speed stirring container 7 reaches the system back pressure, the bottom valve of the high-pressure resistant high-speed stirring container 7 is opened, and the uniformly stirred CO2 foam fluid in the high-pressure resistant high-speed stirring container 7 is introduced into the multi-stage shearing device 9 and the core clamp 12 through a stainless steel pipeline;

[0076] 7) Start the computer monitoring software to monitor the pressure, gas flow rate and liquid phase quality changes in each part of the device; calculate the CO2 saturation S of the sandstone core inside the core holder 12 according to the mass conservation method. CO2 The distribution of CO2 and water inside the sandstone core after CO2 microfoam flooding was detected by low-field nuclear magnetic resonance.

[0077] 8) At least respectively change: the type of foaming agent, foaming agent concentration, brine mineralization, CO2-liquid phase volume ratio, CO2-liquid phase injection rate, mixer speed, back pressure valve pressure to adjust the bubble group size distribution of the micro foam, and observe the effect of the micro foam size on the CO2 saturation and CO2 and water distribution of the sandstone core.

[0078] According to the preferred embodiment of the present invention, in step 3), the porosity of the sandstone core is measured. And the method of permeability K is:

[0079] The sandstone core was placed in a 105°C constant temperature box and dried for 48 hours. After drying, the dry weight of the core was measured as m0. Then, the sandstone core was placed in a beaker containing simulated brine (the brine level was higher than the core), placed in a vacuum chamber, and the vacuum pump was turned on to allow the core to fully absorb the brine in the beaker. After 48 hours, the core was taken out of the vacuum chamber, the surface moisture of the core was wiped dry, and the wet weight of the core was measured as m1. The porosity of the sandstone core was calculated using formula (1): :

[0080]

[0081] In formula (1), ρ is the simulated brine density, D and L are the core diameter and length, respectively.

[0082] The sandstone core saturated with salt water is placed in a core holder, and the confining pressure of the core holder is adjusted to be always 3 MPa higher than the injection pressure. Then, salt water is injected into the sandstone core at a constant volume flow rate, and the pressure at the front and rear ends of the core holder is monitored. After the pressure difference is stable, the permeability K of the sandstone core is calculated according to formula (2):

[0083]

[0084] In formula (2), Q is the volume flow rate of the simulated brine (flow rate range 0.1-1.0 mL / min), μ is the viscosity of the simulated brine, ΔP is the pressure difference between the front and rear ends of the core holder, and A is the cross-sectional area of ​​the sandstone core.

[0085] According to the preferred embodiment of the present invention, in step 7), the CO2 saturation S in the sandstone core can be calculated according to formula (3): CO2 :

[0086]

[0087] In formula (3), PV is the pore volume of sandstone core, V in With V out represent the volume of liquid entering the sandstone core and the volume of liquid flowing out of the sandstone core within the experimental time t, respectively; Q1 is the liquid flow rate injected into the core fluid; t is the liquid pumping time; m is the mass added at the precision electronic balance (which can be regarded as the mass of the liquid phase in the produced fluid); and ρ is the liquid density.

[0088] Next, the present invention will be described in detail with reference to examples and accompanying drawings.

[0089] Example 1

[0090] An application of an indoor preparation device using the aforementioned environmentally friendly CO2 micro-foam fluid to improve the efficiency of capillary CO2 capture in sandstone saline water layers comprises the following steps:

[0091] 1) placing a metal screen 10 and a porous ceramic 10 inside a stainless steel pressure-resistant steel cylinder to form a multi-stage shearing device 9;

[0092] 2) preparing injection fluid, including simulated saline water (the composition of the saline water used in the embodiment is shown in Table 1), a foaming liquid phase (alkyl polyglycoside APG-10 solution with a mass concentration of 0.10wt%) and CO2 gas;

[0093] 3) Place three artificial sandstone cores in a constant temperature box at 105°C. When the mass change does not exceed 0.0010g for two consecutive days, it can be considered that the water inside the core has been evaporated, and its dry weight m0 is weighed using a precision electronic balance; place the artificial sandstone core in a beaker; then place the beaker in an acrylic sealed box, and use a stainless steel pipeline to connect the vacuum pump to the acrylic sealed box. Turn on the vacuum pump to extract the air inside the acrylic sealed box, and the vacuum pump pumping rate is 2-5m 3 / h, the ultimate vacuum is 2-4Pa, and then in this environment, simulated salt water is pumped into the acrylic sealed box until the salt water level is higher than the core surface. The vacuum pump continuously evacuates for 24 hours. After taking out the beaker from the acrylic sealed box, wipe the surface water of the sandstone core and weigh its mass m1 with a precision electronic balance. The porosity of the sandstone core is calculated using formula (1) ; The length, diameter and porosity of the three cores in this example are shown in Table 2;

[0094] 4) The artificial sandstone core saturated with simulated salt water is placed in the core holder 12, and the confining pressure control pump 13 and the core holder 12 are connected by a stainless steel pipeline. The confining pressure control pump 13 is used to load the core holder 12 with confining pressure (the confining pressure is always set to be 3 MPa higher than the injection pressure), and simulated salt water is injected into the sandstone core at a flow rate of 0.50 mL / min. When the pressure at both ends of the core holder 12 is stable, the injection of simulated salt water is stopped; the permeability K of the sandstone core is calculated using formula (2); the permeability information of the three sandstone cores in this embodiment is shown in Table 2.

[0095] 5) Connect the high-pressure nitrogen cylinder 19 and the back-pressure valve 15 with a stainless steel pipeline, and adjust the output pressure of the high-pressure nitrogen cylinder 19 to add the back pressure of the back-pressure valve 15 to the target pressure; in this embodiment, the back pressure is 12 MPa.

[0096] 6) A stainless steel pipeline is used to connect the vacuum oil pump and the high-pressure resistant high-speed stirring container 7, and the vacuum oil pump is used to extract the internal air of the high-pressure resistant high-speed stirring container 7, so that the interior of the high-pressure resistant high-speed stirring container 7 is in a vacuum state;

[0097] 7) For core #1 (CO2 flooding group): connect CO2 cylinder 1 and gas booster pump 2 with a stainless steel pipeline, open the valve of CO2 cylinder 1, adjust the pressure of gas booster pump 2 to 10 MPa, and adjust the gas flow controller 3 to control the CO2 volume flow rate to 2 mL / min;

[0098] For core #2 (ordinary CO2 foam group): connect CO2 cylinder 1 and gas booster pump 2 with stainless steel pipeline, open the valve of CO2 cylinder 1, adjust the pressure of gas booster pump 2 to 10MPa, adjust gas flow controller 3 and advection pump 5 to control the volume flow of CO2 and foaming liquid to 1mL / min respectively, CO2 and foaming liquid do not pass through high-pressure high-speed stirring container and multi-stage shearing device, and the two fluids directly enter the sandstone core in the core holder;

[0099] For 3# core (CO2 microfoam group): use stainless steel pipeline to connect CO2 cylinder 1 and gas booster pump 2, open the valve of CO2 cylinder 1, adjust the pressure of gas booster pump 2 to 10MPa, adjust gas flow controller 3 and horizontal flow pump 5 to control the volume flow rate of CO2 and foaming liquid to 1mL / min respectively, inject CO2 and foaming liquid into high-pressure high-speed stirring container 7 at the same time, and connect high-pressure high-speed stirring container 7 with multi-stage shearing device 9 and core clamp 12 with stainless steel pipeline; at the same time, start the electric stirrer to the maximum speed of 3000rpm; when the internal pressure of high-pressure high-speed stirring container 7 reaches the system back pressure, open the bottom valve of high-pressure high-speed stirring container, and the CO2 foam fluid stirred evenly inside the high-pressure high-speed stirring container is introduced into the multi-stage shearing device 9 and core clamp 12 in sequence through the stainless steel pipeline.

[0100] In the above three groups of displacement experiments, the outlet end of the core holder 12 was connected to the two-dimensional high-pressure visual observation chamber 14 by a stainless steel pipeline, and the two-dimensional high-pressure visual observation chamber 14 was placed under an optical microscope 20 to observe the microscopic morphology of the displaced fluid.

[0101] 8) Start the computer monitoring software to monitor the pressure, gas flow rate and liquid phase quality changes in each part of the device; calculate the CO2 saturation S of the sandstone core inside the core holder according to the mass conservation method. CO2 The distribution of CO2 and water inside the sandstone core after CO2 microfoam flooding was detected by low-field nuclear magnetic resonance.

[0102] See also Figure 2 , the median particle size d of CO2 flooding, ordinary CO2 foam flooding and CO2 micro foam flooding 50The diameters of the CO2 bubbles are 170.75, 60.38 and 33.65 μm respectively. After adding the high-speed mixer and multi-stage shearing device, the bubble size of the CO2 foam is significantly reduced. The small-sized bubble group is conducive to more CO2 bubbles entering the small pores of the sandstone core, expanding the scope of the CO2-containing fluid in the sandstone core. Figure 3 After CO2 flooding, ordinary CO2 foam flooding and CO2 microfoam flooding, the CO2 saturation S of the sandstone core CO2 They are 35.71%, 62.43% and 81.68% respectively. This means that CO2 microfoam will be able to effectively improve the storage efficiency of CO2 in sandstone, and most of the water phase in the sandstone is displaced by CO2 microfoam. Figure 4 After the displacement, for the CO2 microfoam group, the water phase saturation of the overall sandstone core dropped to about 20% and was evenly distributed. The CO2 microfoam showed a uniform piston-type displacement pattern in the sandstone core, which helped to greatly improve the storage efficiency of CO2 in the sandstone saline layer.

[0103] Table 1 Composition of simulated salt water in this embodiment

[0104] Inorganic salt types NaCl <![CDATA[CaCl2]]> <![CDATA[MgCl2·6H2O]]> <![CDATA[NaHCO3]]> <![CDATA[Na2SO4]]> total Concentration / (g / L) 75.26 19.99 9.61 0.68 1.17 101.60

[0105] Table 2 Geometric dimensions, porosity and permeability information of the three cores in this example

[0106] Core number Diameter / cm Length / cm Porosity / % Permeability / mD 1# 2.47 10.25 19.17 118.90 2# 2.51 10.17 19.99 107.10 3# 2.45 10.07 19.66 136.99

[0107] The above description is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be understood by anyone familiar with the technology within the technical scope disclosed by the present invention should be included in the scope of the present invention.

Claims

1. An indoor preparation device for an environmentally friendly CO2 micro-foam fluid, characterized in that: include: A gas injection passage is composed of a CO2 gas cylinder (1), a gas booster pump (2) and a gas flow controller (3); a liquid injection passage is composed of a water source (4), a horizontal flow pump (5) and a piston container (6); the gas injection passage and the liquid injection passage connected in parallel are merged into a high-pressure high-speed stirring container (7); The rear part of the high-pressure resistant high-speed stirring container (7) is connected in sequence to a multi-stage shearing device (9), a core holder (12), a two-dimensional high-pressure visual observation cabin (14), a back-pressure valve (15) and a liquid-receiving measuring cylinder (17), and the liquid-receiving measuring cylinder (17) is placed on a tray of a precision electronic balance (16); the mixed fluid after being uniformly stirred at high speed in the high-pressure resistant high-speed stirring container (7) flows to the multi-stage shearing device (9), the core holder (12), the two-dimensional high-pressure visual observation cabin (14), the back-pressure valve (15) and the liquid-receiving measuring cylinder (17) in sequence; The back pressure control interface of the back pressure valve (15) is connected to a high-pressure nitrogen gas cylinder (19) to control the back pressure of the back pressure valve (15).

2. The indoor preparation device of the environmentally friendly CO2 micro-foam fluid according to claim 1, characterized in that: A first pressure sensor (21) is arranged between the multi-stage shearing device (9) and the core holder (12), and a second pressure sensor (23) is arranged between the core holder (12) and the two-dimensional high-pressure visual observation chamber (14). The first pressure sensor (21) and the second pressure sensor (23) communicate with a monitoring computer (22) via a pressure and quality data acquisition box (18), and are respectively used to monitor the displacement pressure of the CO2 foam fluid at the inlet and outlet of the core holder (12), and are used to obtain the dynamic pressure difference change of the CO2 foam during the displacement process in real time; The precision electronic balance (16) communicates with the monitoring computer (22) via the pressure and quality data acquisition box (18) and is used to obtain the dynamic changes in the quality of the liquid phase in the output fluid in real time by real-time monitoring the changes in the quality data of the precision electronic balance (16).

3. The indoor preparation device of the environmentally friendly CO2 micro-foam fluid according to claim 1, characterized in that: An electric stirrer is installed on the top of the high-pressure resistant high-speed stirring container (7), and the maximum speed of the electric stirrer is 3000 rpm; the high-pressure resistant high-speed stirring container (7) is connected to the stirring paddle speed control box (8) through an electric wire, and the stirring paddle speed control box (8) is adjusted to adjust the stirring paddle speed of the electric stirrer; The inlet of the high-pressure resistant high-speed stirring container (7) is located at the top, and the gas injection passage and the liquid injection passage merge at the top inlet of the high-pressure resistant high-speed stirring container (7); the outlet of the high-pressure resistant high-speed stirring container (7) is located at the bottom, and the foam fluid that has been uniformly stirred flows into the multi-stage shearing device (9) through the bottom of the high-pressure resistant high-speed stirring container (7).

4. The indoor preparation device of the environmentally friendly CO2 micro-foam fluid according to claim 1, characterized in that: The multi-stage shearing device (9) comprises a stainless steel pressure-resistant steel cylinder, a metal screen (10) and a porous ceramic (11), wherein the metal screen (10) and the porous ceramic (11) are arranged from left to right in the stainless steel pressure-resistant steel cylinder, wherein the metal screen (10) is woven from 304 stainless steel, the mesh number range is 1600-2000 mesh, the metal screen (10) has a diameter of 25 mm and a length of 30 mm; the porous ceramic (11) has an average pore size of 5 μm, a diameter of 25 mm and a length of 50 mm; the CO2 foam fluid flowing out of the outlet of the high-pressure resistant high-speed stirring container (7) flows through the metal screen (10) and the porous ceramic (11) in turn, and is sheared step by step to achieve the purpose of reducing the particle size of the bubble group.

5. The indoor preparation device of the environmentally friendly CO2 micro-foam fluid according to claim 1, characterized in that: The two-dimensional high-pressure visual observation chamber (14) is placed under an optical microscope (20), and the CO2 micro-foam fluid flowing out of the core holder (12) enters the two-dimensional high-pressure visual observation chamber (14) to observe the particle size distribution of the CO2 micro-foam fluid; The visualization part of the two-dimensional high-pressure visual observation chamber (14) is a sapphire glass with high-pressure resistance, and its diameter and thickness are 100 and 10 mm respectively; the inner thickness of the two-dimensional high-pressure visual observation chamber (14) is 1 mm; the maximum operating temperature and pressure of the two-dimensional high-pressure visual observation chamber (14) are 130° C. and 25 MPa respectively.

6. The indoor preparation device of the environmentally friendly CO2 micro-foam fluid according to claim 1, characterized in that: The working pressure range of the gas flow controller (3) is 0.1-20 MPa, and the gas flow rate control range is 0.10-9.99 mL / min; the working pressure range of the horizontal flow pump (5) is 0.1-42 MPa, and the liquid flow rate control range is 0.001-9.999 mL / min.

7. The indoor preparation device of the environmentally friendly CO2 micro-foam fluid according to claim 1, characterized in that: The middle interface of the core holder (12) is connected to the confining pressure control pump (13) to achieve the purpose of controlling the internal confining pressure of the core holder (12) in real time; the foaming liquid adopts non-ionic surfactant alkyl polyglycoside APG, and according to the different lengths of the hydrophobic segments of the APG molecules, APG includes APG-0810, APG-10, APG-0812 and APG-0814, and its composition is 0.1-1.0 parts of APG and 100 parts of distilled water.

8. An application of an indoor preparation device for an environmentally friendly CO2 micro-foam fluid according to any one of claims 1 to 7 in improving the efficiency of capillary capture of CO2 in sandstone saline water layers, characterized in that: The following steps are involved: 1) placing a metal screen (10) and a porous ceramic (11) inside a stainless steel pressure-resistant steel cylinder to form a multi-stage shearing device (9); 2) Prepare injection fluids, including simulated saline water, foaming liquid phase and CO2 gas; 3) placing the sandstone core in a small acrylic sealed box, and starting the vacuum pump to extract the air inside the acrylic sealed box, and then pumping simulated salt water into the acrylic sealed box until the liquid level of the simulated salt water is higher than the top of the core, so that the core is fully saturated with the simulated salt water, and the porosity φ of the sandstone core is measured; then placing the core in a core holder (12) and using a confining pressure control pump (13) to track the confining pressure of the holder, injecting simulated salt water into the sandstone core at a certain flow rate, and measuring the permeability K of the sandstone core; 4) Using a high-pressure nitrogen gas cylinder (19) to add back pressure to the back pressure valve (15) to reach the target pressure; 5) Open the valve of the CO2 cylinder (1), adjust the pressure of the gas booster pump (2), adjust the gas flow controller (3) and the horizontal flow pump (5) to control the volume flow of CO2 and the foaming liquid respectively, and inject the CO2 and the foaming liquid into the high-pressure high-speed stirring container (7) at the same time; and simultaneously start the electric stirrer to a maximum speed of 3000 rpm; 6) When the internal pressure of the high-pressure resistant high-speed stirring container (7) reaches the system back pressure, the bottom valve of the high-pressure resistant high-speed stirring container (7) is opened, and the CO2 foam fluid stirred evenly inside the high-pressure resistant high-speed stirring container (7) is introduced into the multi-stage shearing device (9) and the core clamp (12); 7) Start the computer monitoring software to monitor the pressure, gas flow rate and liquid phase quality changes in each part of the device; calculate the CO2 saturation S of the sandstone core inside the core holder (12) according to the mass conservation law. CO2 ; 8) At least respectively change: the type of foaming agent, foaming agent concentration, brine mineralization, CO2-liquid phase volume ratio, CO2-liquid phase injection rate, mixer speed, back pressure valve pressure to adjust the bubble group size distribution of the micro foam, and observe the effect of the micro foam size on the CO2 saturation and CO2 and water distribution of the sandstone core.

9. The use according to claim 8, characterized in that: In step 3), the method for measuring the porosity φ and permeability K of the sandstone core is: The sandstone core was placed in a 105℃ constant temperature box and dried for 48 hours. After drying, the dry weight of the core was measured as m0. Then, the sandstone core was placed in a beaker containing simulated brine, with the brine level higher than the core. The core was placed in a vacuum chamber and the vacuum pump was turned on to allow the core to fully absorb the brine in the beaker. After 48 hours, the core was taken out of the vacuum chamber, the surface moisture of the core was wiped dry, and the wet weight of the core was measured as m1. The porosity φ of the sandstone core was calculated using formula (1): In formula (1), ρ is the simulated brine density, D and L are the core diameter and length, respectively; The sandstone core saturated with salt water is placed in a core holder, and the confining pressure of the core holder is adjusted to be always 3 MPa higher than the injection pressure. Then, salt water is injected into the sandstone core at a constant volume flow rate, and the pressure at the front and rear ends of the core holder is monitored. After the pressure difference is stable, the permeability K of the sandstone core is calculated according to formula (2): In formula (2), Q is the volume flow rate of the simulated brine, with a flow rate range of 0.1-1.0 mL / min; μ is the viscosity of the simulated brine, ΔP is the pressure difference between the front and rear ends of the core holder; and A is the cross-sectional area of ​​the sandstone core.

10. The use according to claim 8, characterized in that: In step 7), the CO2 saturation S in the sandstone core is calculated according to formula (3). CO2 : In formula (3), PV is the pore volume of the sandstone core; Q1 is the liquid flow rate of the fluid injected into the core; t is the liquid pumping time; m is the mass added at the precision electronic balance; ρ is the liquid density.

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