Carbon dioxide and surfactant mixing device and displacement simulation method

Abstract

The invention provides a carbon dioxide and surfactant mixing device and a displacement simulation method. The carbon dioxide and surfactant mixing device comprises a proportioning box, a plurality of ejectors are arranged in the first-stage space, at least one ejector is used for ejecting carbon dioxide, and at least another ejector is used for ejecting a surfactant; the polymerizer is arranged in the first-stage space and located below the ejector, carbon dioxide ejected by the ejector and a surfactant are preliminarily mixed above the polymerizer to form gas-liquid mixed bubbles, then the gas-liquid mixed bubbles are polymerized in the polymerizer, and the gas-liquid mixed bubbles flow into the second-stage space; the cutting device is arranged in the second-stage space and is used for cutting gas-liquid mixed bubbles flowing into the polymerizer into fine micro-nano bubbles; and the fusion device is arranged in the third-stage space and is used for fully mixing carbon dioxide and a surfactant. The problem that carbon dioxide and surfactant molecules are difficult to uniformly mix in a physical simulation experiment device in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield development equipment, in particular to a carbon dioxide and surfactant mixing device and a displacement simulation method. Background Art

[0002] With the rise of industry, carbon emissions are gradually increasing, causing great impact on the environment. The research, development, promotion and application of CCUS technology (Carbon Capture, Utilization and Storage) can make an important contribution to reducing carbon emissions.

[0003] Studies have found that the mixture of carbon dioxide and surfactants significantly improves the efficiency of oil reservoir production. Studies have shown that although many gases can improve the efficiency of crude oil displacement, only CO2 can reduce the residual oil saturation to near 0. Indoor research on CO2 displacement to improve oil recovery began in the 1950s, and field tests began in the 1960s. In the 1970s, with the laying of CO2 pipelines, the scale began to expand. In recent years, my country has conducted more and more research on CO2 flooding, and has also carried out field applications in some oil fields. However, since the gas viscosity of CO2 flooding is much lower than that of crude oil, the gravity separation of gas and crude oil is serious, resulting in gas bypass and fingering, and the displacement efficiency is low. As early as 1955, some researchers have realized that in the process of gas flooding, injecting surfactants to form foam inside the reservoir can reduce gas mobility. Field practice has proved that foam is very effective in reducing CO2 mobility, which can generally reduce CO2 mobility by more than 50%, improve the flow conditions of displacement fluid in heterogeneous oil layers, control gas fingering, and delay the breakthrough time of CO2 gas. It also has the advantages of both CO2 drive and foam drive - high displacement efficiency and good mobility control ability.

[0004] At present, the physical simulation experimental device for carbon dioxide and surfactants is still very imperfect. Generally, a horizontal flow pump is used to directly compress CO2 gas and surfactant solution at a certain flow rate and then inject them (a device and method for determining the surfactant concentration distribution of CO2 emulsion during seepage, CN 104792938B; a method for improving the recovery rate of carbon dioxide flooding using surfactants, CN 105257264 A). However, the molecular structure and properties of surfactants determine that they will form micelles in water, that is, tiny particles formed by the aggregation of surfactant molecules. These micelles can move and diffuse freely in water, but they cannot effectively form micelles in carbon dioxide. Therefore, surfactant molecules are easy to gather on the surface of the liquid or gather in certain areas, resulting in uneven mixing. Therefore, the current technical methods cannot solve the problem of uneven mixing well (Luo, 2018, Effects of the non-ionicsurfactant (CiPOj) on the interfacial tension behavior between CO2 and crudeoil, Energy & Fuel). In addition, the difference in solubility between carbon dioxide and surfactants may also lead to uneven mixing (Kuang Nianjie, 2020, Current status of research on surfactants to reduce the minimum miscible pressure of CO2 flooding, petrochemical applications).

[0005] Carbon dioxide is a non-polar gas, while surfactant molecules have a certain polarity. Therefore, when they are mixed together, the interaction between carbon dioxide and surfactant molecules is relatively weak, making it difficult to form a uniform mixture. Conventional experimental methods usually inject carbon dioxide and fluid directly into the model in a certain proportion to mix them inside the model, but due to the difference in the properties of carbon dioxide and fluid, it is difficult to evenly store tiny gas-liquid mixed bubbles in the surfactant.

[0006] That is to say, the physical simulation experimental device in the prior art has the problem that carbon dioxide and surfactant molecules are difficult to mix evenly. Summary of the invention

[0007] The main purpose of the present invention is to provide a carbon dioxide and surfactant mixing device and a displacement simulation method to solve the problem that carbon dioxide and surfactant molecules are difficult to mix evenly in physical simulation experimental devices in the prior art.

[0008] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a device for mixing carbon dioxide and surfactant, comprising: a proportioning box, the proportioning box having a primary space, a secondary space and a tertiary space connected in sequence along the direction of gravity; a plurality of injectors, the plurality of injectors are arranged in the primary space, at least one injector is used to inject carbon dioxide, and at least another injector is used to inject surfactant; an aggregator, the aggregator is arranged in the primary space, and the aggregator is located below the injector, the carbon dioxide and surfactant sprayed by the injector are preliminarily mixed above the aggregator to form gas-liquid mixed bubbles, which are then aggregated in the aggregator and flow into the secondary space; a cutting device, the cutting device is arranged in the secondary space, and the cutting device is used to cut the gas-liquid mixed bubbles flowing into the aggregator into fine micro-nano bubbles; and a fusion device, the fusion device is arranged in the tertiary space, and the fusion device is used to fully mix the carbon dioxide and the surfactant.

[0009] Furthermore, the injector is a grid-shaped injector, so that the injected surfactant is in the form of small bubbles.

[0010] Furthermore, the aggregater has a conical aggregate surface, the small diameter end of the conical aggregate surface is closer to the secondary space than the large diameter end of the conical aggregate surface, and the conical aggregate surface is provided with a plurality of first outlets.

[0011] Furthermore, the carbon dioxide and surfactant mixing device also includes a converging plate, which is located below the cutting device. The converging plate has multiple second outlets. The micro-nano bubbles in the secondary space flow into the tertiary space through the second outlets. The first outlet and the second outlet are staggered in the circumferential direction.

[0012] Furthermore, the converging plate is tapered, and the cross-sectional area of ​​the converging plate gradually decreases toward the direction approaching the tertiary space.

[0013] Furthermore, the cutting device includes: a driving device; a cutting impeller, the driving device is drivingly connected to the cutting impeller to drive the cutting impeller to rotate, and the cutting impeller is used to cut the gas-liquid mixed bubbles into tiny micro-nano bubbles.

[0014] Furthermore, the fusion device includes a plurality of rotating blade devices, and the plurality of rotating blade devices are arranged in a three-level space from top to bottom, and the rotation speeds of the rotating blade devices are different.

[0015] Furthermore, among the plurality of rotating blade devices, the rotating blade device close to the secondary space has the largest rotation speed.

[0016] Furthermore, the rotation speeds of the plurality of rotating blade devices decrease step by step from top to bottom.

[0017] Furthermore, the fusion device also includes a multi-stage variable speed planetary drive motor, and the plurality of rotating blade devices are connected to the multi-stage variable speed planetary drive motor.

[0018] Furthermore, the proportioning box has a conical structure, and the cross-sectional area of ​​the proportioning box gradually decreases from the primary space to the tertiary space.

[0019] According to another aspect of the present invention, a displacement simulation method is provided. The displacement simulation method adopts the above-mentioned carbon dioxide and surfactant mixing device, and the displacement simulation method comprises: step S10: configuring simulated oil of preset viscosity according to reservoir conditions; step S20: preparing a physical model according to reservoir parameters, and testing basic parameters of the physical model; step S30: preparing carbon dioxide and surfactant, and two injection pumps, and correspondingly connecting the injection pumps to the injectors of the carbon dioxide and surfactant mixing device; step S40: calculating the preset injection rate of carbon dioxide and the preset injection rate of surfactant according to the ratio number and the required environmental conditions; step S50: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S51: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S60: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S70: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S80: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S90: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S110: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S120: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S130: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant; step S140: injecting carbon dioxide and surfactant into the mixture according to the ratio of carbon dioxide and surfactant. The carbon dioxide and surfactant are injected into the mixing device at a preset injection rate to form a compound agent after mixing; step S60: after the natural core is extracted and dried, the natural core is arranged and installed, and the saturation amount is recorded after it is fully saturated with formation water; step S70: the water in the natural core is displaced by the prepared saturated oil sample, the oil-water distribution of the physical model is established, and the bound water saturation is calculated; step S80: the mixed compound agent is injected into the physical model through the transmission pipeline to carry out displacement experiments on the oil reservoir and record the displacement data; step S90: after each group of experiments, the natural core is cleaned and dried, the ratio of carbon dioxide to the surfactant is changed, and the above steps S40 to S90 are repeated until all the ratio experiments are completed.

[0020] Furthermore, in the process of injecting the mixed compound agent into the physical model through the delivery pipeline to conduct displacement experiments in the oil reservoir and record the displacement data, the displacement time, pump reading, injection pressure, injection rate, annular pressure and back pressure are recorded, and the produced gas-oil ratio and the separated oil, gas and water amounts are monitored.

[0021] Furthermore, in the process of cleaning the natural core after each set of experiments, the natural core was first cleaned with petroleum ether and anhydrous alcohol, and then blown with nitrogen.

[0022] Furthermore, the oil-water distribution of the physical model simulates the original oil-water distribution of the formation.

[0023] According to the technical solution of the present invention, a device for mixing carbon dioxide and a surfactant comprises a proportioning box, a plurality of ejectors, an aggregator, a cutting device and a fusion device, wherein the proportioning box comprises a primary space, a secondary space and a tertiary space which are sequentially connected along the direction of gravity; the plurality of ejectors are arranged in the primary space, at least one ejector is used for ejecting carbon dioxide, and at least another ejector is used for ejecting a surfactant; the aggregator is arranged in the primary space, and the aggregator is located below the ejector, and the carbon dioxide and the surfactant ejected by the ejector are preliminarily mixed above the aggregator to form gas-liquid mixed bubbles, which are then aggregated in the aggregator and flow into the secondary space; the cutting device is arranged in the secondary space, and the cutting device is used for cutting the gas-liquid mixed bubbles flowing into the aggregator into fine micro-nano bubbles; the fusion device is arranged in the tertiary space, and the fusion device is used for fully mixing the carbon dioxide and the surfactant.

[0024] The proportioning box provides a mixing space for carbon dioxide and surfactants so that carbon dioxide and surfactants can be evenly mixed. By setting multiple injectors in the primary space, different injectors spray carbon dioxide and surfactants into the primary space respectively. At the same time, the surfactants sprayed by the injectors are small bubbles, which increases the contact area between the surfactant and carbon dioxide. By setting a polymerizer below the injector, the sprayed carbon dioxide and surfactants can be quickly contacted and polymerized. After the gas-liquid mixed bubbles formed by carbon dioxide and surfactants are polymerized to a certain amount, they will flow into the secondary space. The cutting device in the secondary space cuts the gas-liquid mixed bubbles into tiny micro-nano bubbles to effectively increase the gas-liquid contact area, so that carbon dioxide and surfactants can be mixed more fully. After being cut into micro-nano bubbles, the gas-liquid mixed bubbles enter the tertiary space, and the fusion device mixes the micro-nano bubbles to make the carbon dioxide and surfactants evenly mixed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0026] Figure 1 A schematic structural diagram of a device for mixing carbon dioxide and surfactant according to an optional embodiment of the present invention is shown;

[0027] Figure 2 Shows Figure 1 An angled view of the aggregator;

[0028] Figure 3 Shows Figure 1 An angled view of the central converging plate;

[0029] Figure 4A state diagram showing the fluid distribution in the three-level space in an optional embodiment of the present invention;

[0030] Figure 5 It shows a schematic structural diagram of a multi-stage variable speed planetary drive motor in an optional embodiment of the present invention;

[0031] Figure 6 A schematic structural diagram of a rotating blade device in an optional embodiment of the present invention is shown;

[0032] Figure 7 A schematic structural diagram of an axle fixing device in an optional embodiment of the present invention is shown;

[0033] Figure 8 The oil displacement efficiency of the experimental groups with different mixing ratios in the present invention is shown.

[0034] The above drawings include the following reference numerals:

[0035] 10. Proportioning box; 11. Primary space; 12. Secondary space; 13. Tertiary space; 20. Ejector; 30. Aggregator; 31. Conical aggregation surface; 311. Small diameter end; 312. Large diameter end; 313. First outlet; 40. Cutting device; 41. Cutting impeller; 50. Fusion device; 51. Rotating blade device; 52. Multi-stage variable speed planetary drive motor; 60. Converging plate; 61. Second outlet. DETAILED DESCRIPTION

[0036] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0038] In the present invention, unless otherwise specified, the directional words used, such as "up, down, top, bottom", usually refer to the directions shown in the drawings, or to the components themselves in the vertical, perpendicular or gravity directions; similarly, for ease of understanding and description, "inside and outside" refer to the inside and outside relative to the outline of each component itself, but the above-mentioned directional words are not used to limit the present invention.

[0039] The main purpose of the present invention is to provide a carbon dioxide and surfactant mixing device and a displacement simulation method to solve the problem that carbon dioxide and surfactant molecules are difficult to mix evenly in physical simulation experimental devices in the prior art.

[0040] like Figures 1 to 8As shown, the carbon dioxide and surfactant mixing device includes a proportioning box 10, a plurality of ejectors 20, an aggregator 30, a cutting device 40 and a fusion device 50. The proportioning box 10 has a primary space 11, a secondary space 12 and a tertiary space 13 which are sequentially connected along the gravity direction; a plurality of ejectors 20 are arranged in the primary space 11, at least one ejector 20 is used to eject carbon dioxide, and at least another ejector 20 is used to eject surfactant; the aggregator 30 is arranged in the primary space 11, and the aggregator 30 is located below the ejector 20, the carbon dioxide and surfactant ejected from the ejector 20 are initially mixed above the aggregator 30 to form gas-liquid mixed bubbles, which are then aggregated in the aggregator 30 and flow into the secondary space 12; the cutting device 40 is arranged in the secondary space 12, and the cutting device 40 is used to cut the gas-liquid mixed bubbles flowing into the aggregator 30 into fine micro-nano bubbles; the fusion device 50 is arranged in the tertiary space 13, and the fusion device 50 is used to fully mix the carbon dioxide and the surfactant.

[0041] The proportioning box 10 provides a mixing space for carbon dioxide and surfactant so that carbon dioxide and surfactant are evenly mixed. By arranging multiple injectors 20 in the primary space 11, different injectors 20 respectively spray carbon dioxide and surfactant into the primary space 11, and the surfactant sprayed by the injector 20 is a small bubble, which increases the contact area between the surfactant and carbon dioxide. By arranging a polymerizer 30 below the injector 20, the ejected carbon dioxide and surfactant are quickly contacted and polymerized, and the gas-liquid mixed bubbles formed by carbon dioxide and surfactant are polymerized to a certain amount and flow into the secondary space 12. The cutting device 40 in the secondary space 12 cuts the gas-liquid mixed bubbles into fine micro-nano bubbles to effectively increase the gas-liquid contact area, so that carbon dioxide and surfactant are mixed more fully. After being cut into micro-nano bubbles, the gas-liquid mixed bubbles enter the tertiary space 13, and the fusion device 50 mixes the micro-nano bubbles so that carbon dioxide and surfactant are evenly mixed.

[0042] Specifically, the ejector 20 is a grid-shaped ejector, so that the ejected surfactant is small bubbles. The grid-shaped ejector makes the ejected surfactant small bubbles, and when the surfactant and carbon dioxide are initially in contact, there is a larger contact area, which is conducive to the full mixing of carbon dioxide and the surfactant, and effectively improves the mixing efficiency of carbon dioxide and the surfactant.

[0043] exist Figure 1In the specific embodiment shown, the aggregator 30 has a conical aggregating surface 31, a small diameter end 311 of the conical aggregating surface 31 is closer to the secondary space 12 than a large diameter end 312 of the conical aggregating surface 31, and a plurality of first outlets 313 are provided on the conical aggregating surface 31. Providing the conical aggregating surface 31 on the aggregator 30 is conducive to rapid aggregation of gas-liquid mixed bubbles and rapid flow of gas-liquid mixed bubbles into the secondary space.

[0044] The first outlet 313 is close to the edge of the conical aggregation surface 31 relative to the center of the conical aggregation surface 31, or in other words, the first outlet 313 is set at the upper part of the conical aggregation surface 31, so that the gas-liquid mixed bubbles gather a certain amount and then flow into the secondary space 12 through the first outlet 313.

[0045] Optionally, the small diameter end 311 of the conical convergent surface 31 is a solid structure, so that the fluid flows downward through the first outlet 313 .

[0046] like Figures 1 to 3 As shown, the carbon dioxide and surfactant mixing device also includes a convergence plate 60, which is located below the cutting device 40. The convergence plate 60 has a plurality of second outlets 61. The micro-nano bubbles in the secondary space 12 flow into the tertiary space 13 through the second outlets 61, and the first outlet 313 and the second outlet 61 are offset in the circumferential direction. The convergence plate 60 is used to converge the micro-nano bubbles formed after being cut by the cutting device 40, so that the micro-nano bubbles are quickly converged into the tertiary space 13 for mixing. The circumferential offset of the first outlet 313 and the second outlet 61 means that the projection of the first outlet 313 to the convergence plate 60 is offset from the second outlet 61, so as to avoid the gas-liquid mixed bubbles that flow into the secondary space 12 through the first outlet 313 directly flowing into the tertiary space 13 through the second outlet 61, which effectively increases the mixing effect of carbon dioxide and surfactant.

[0047] like Figure 1 As shown, the converging plate 60 is conical, and the cross-sectional area of ​​the converging plate 60 gradually decreases toward the direction close to the tertiary space 13. Setting the converging plate 60 to be conical is conducive to the micro-nano bubbles converging on the converging plate 60 and flowing into the tertiary space 13 quickly.

[0048] exist Figure 3 In the specific embodiment shown, the second outlet 61 is close to the edge of the converging plate 60 relative to the center of the converging plate 60, or in other words, the second outlet 61 is arranged at the upper part of the converging plate 60 so that the micro-nano bubbles converge to a certain amount and then flow into the tertiary space 13.

[0049] Optionally, the conical tip of the converging plate 60 is a solid structure, so that the fluid flows into the tertiary space 13 through the second outlet 61 .

[0050] like Figure 1As shown, the cutting device 40 includes a driving device and a cutting impeller 41, and the driving device is connected to the cutting impeller 41 to drive the cutting impeller 41 to rotate at a high speed, and the cutting impeller 41 is used to cut the gas-liquid mixed bubbles into tiny micro-nano bubbles. The driving device drives the cutting impeller 41 to rotate, and the high-speed rotating cutting impeller 41 cuts the gas-liquid mixed bubbles into dozens of nanometers to several micrometers, and finally forms micro-nano bubbles of micron and nanometer levels. The more micro-nano bubbles there are, the larger the surface area is compared with large bubbles, which effectively increases the contact area between carbon dioxide and surfactants, and improves the uniformity of mixing carbon dioxide and surfactants. Through cooperation with the converging plate 60, the micro-nano bubbles are gathered to a certain amount and then flow into the tertiary space 13.

[0051] like Figure 1 As shown, the fusion device 50 includes a plurality of rotating blade devices 51, which are arranged in the three-level space 13 from top to bottom, and each rotating blade device 51 has a different rotation speed. The different rotation speeds of the plurality of rotating blade devices 51 enable the carbon dioxide and the surface fusion agent to fuse more fully.

[0052] Specifically, the rotating blade device 51 near the secondary space 12 among the multiple rotating blade devices 51 has the highest rotation speed. This arrangement enables the rotating blade device 51 at the top to rotate at the fastest speed, receiving the mixed fluid flowing out of the secondary space 12, causing the mixed fluid to move downward rapidly, so that the surfactant and carbon dioxide form a horizontal and vertical flow cycle in the tertiary space, that is, the surfactant and carbon dioxide flow in a spiral shape in the tertiary space.

[0053] Specifically, the rotation speeds of the plurality of rotating blade devices 51 decrease gradually from top to bottom. The rotating blade device 51 at the bottom rotates relatively slowly, which is beneficial to overcome the influence of gravity separation and achieve full mixing of carbon dioxide and surfactant.

[0054] like Figure 5 As shown, the fusion device 50 also includes a multi-stage variable speed planetary drive motor 52, and the plurality of rotating blade devices 51 are connected to the multi-stage variable speed planetary drive motor. By setting the multi-stage variable speed planetary drive motor, the plurality of rotating blade devices 51 rotate together, but the rotation speed of the plurality of rotating blade devices 51 decreases step by step.

[0055] Of course, the fusion device 50 may include a plurality of motors, and the plurality of motors are connected to the plurality of rotating blade devices 51 in a one-to-one correspondence. When working, different motors are set to different rotational speeds.

[0056] like Figure 1As shown, the proportioning box 10 is a conical structure, and the cross-sectional area of ​​the proportioning box 10 gradually decreases from the primary space 11 to the tertiary space 13. By setting the proportioning box 10 as a conical structure, it is beneficial for the mixed fluid to converge and flow downward quickly, and it is beneficial for the carbon dioxide and the surfactant to be fully mixed.

[0057] The working principle of the carbon dioxide and surfactant mixing device in the present application is to use a grid-shaped ejector to disperse the surfactant into very small bubbles, and the carbon dioxide and the surfactant are contacted and mixed in the primary space 11 to accelerate the mixing speed. The preliminarily mixed fluid is then introduced into the secondary space 12 through the polymerizer 30, and the high-speed rotating cutting impeller 41 cuts the gas-liquid mixed bubbles into tens of nanometers to several microns to form micro-nano bubbles.

[0058] Due to the gravity difference between surfactants and carbon dioxide, surfactants and carbon dioxide are easily separated, resulting in uneven mixing. In order to produce a uniformly mixed fluid, a step-by-step mixing method is adopted in the three-level space to achieve a more uniform mixing effect.

[0059] The present application effectively increases the gas-liquid contact area by adopting a grid-shaped ejector and a polymerizer 30 with a large surface, thereby making the mixing speed faster. The cutting device 40 with a cutting impeller 41 is used to increase the volume of micro-nano bubbles, and the mixture is mixed step by step in the space through a step-by-step stirring fusion device 50, thereby achieving a more uniform mixing effect.

[0060] The carbon dioxide and surfactant mixing device can effectively improve the mixing efficiency and mixing quality, thereby improving the performance and reliability of the mixed fluid. Compared with the existing CO2 compound agent displacement simulator, the present application can not only conveniently regulate the displacement effect of different CO2 and surfactant ratios on the oil reservoir, but also the carbon dioxide and surfactant can be mixed more evenly, and can exert better effects when injected into the model, thereby increasing the oil recovery efficiency under the same injection volume and greatly increasing the economic benefits.

[0061] The present application also provides a displacement simulation method, which uses the above-mentioned carbon dioxide and surfactant mixing device, and the displacement simulation method includes: step S10: configuring simulated oil with a preset viscosity according to reservoir conditions; step S20: preparing a physical model according to reservoir parameters, and testing basic parameters of the physical model; step S30: preparing carbon dioxide and surfactant, and two injection pumps, and correspondingly connecting the injection pumps to the injector 20 of the carbon dioxide and surfactant mixing device; step S40: calculating a preset injection rate of carbon dioxide and a preset injection rate of the surfactant according to the ratio and the required environmental conditions; step S50: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S60: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S70: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S80: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S90: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S110: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S120: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S130: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S140: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S150: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S161: injecting carbon dioxide and surfactant according to the corresponding preset injection rate; step S171: injecting carbon dioxide and surfactant according to the corresponding preset injection rate. Assume that the injection rate is set to inject carbon dioxide and the surfactant into the mixing device to form a compound agent after mixing; step S60: after the natural core is extracted and dried, the natural core is arranged and installed, and the saturation amount is recorded after it is fully saturated with formation water; step S70: the water in the natural core is displaced by the prepared saturated oil sample, the oil-water distribution of the physical model is established, and the bound water saturation is calculated; step S80: the mixed compound agent is injected into the physical model through the transmission pipeline to carry out the displacement experiment of the oil reservoir and record the displacement data; step S90: after each group of experiments, the natural core is cleaned and dried, the ratio of carbon dioxide to the surfactant is changed, and the above steps S40 to S90 are repeated until all the ratio experiments are completed.

[0062] The physical model refers to the permeability, pore size and location simulated by the core according to the reservoir conditions.

[0063] The displacement simulation method uses the above-mentioned carbon dioxide and surfactant mixing device to conveniently adjust the ratio of carbon dioxide and surfactant, so as to simulate the displacement effect of the mixed fluid on the reservoir under different ratios, which is conducive to selecting the ratio with the best displacement effect.

[0064] It should be noted that the physical model simulates the reservoir conditions.

[0065] Specifically, when the mixed compound is injected into the physical model through the delivery pipeline to conduct displacement experiments in the reservoir and record the displacement data, the displacement time, pump reading, injection pressure, injection speed, annular pressure and back pressure are recorded, and the produced gas-oil ratio and the separated oil, gas and water volumes are monitored. Recording the above parameters is conducive to comparison under various ratios to select the most preferred ratio.

[0066] Specifically, in the process of cleaning the natural core after each set of experiments, the natural core is first cleaned with petroleum ether and anhydrous alcohol, and then blown with nitrogen. In this way, the mixed fluid of carbon dioxide and surfactant left in the previous set of experiments can be cleaned to avoid affecting the next set of experiments, thereby improving the accuracy of each set of experiments.

[0067] Specifically, the oil-water distribution of the physical model simulates the original oil-water distribution of the formation, so that the simulation results obtained will be closer, which is conducive to obtaining better experimental results.

[0068] The following is a detailed explanation using a specific example.

[0069] Step S10: preparing heavy oil with a specific gravity of 0.88 according to reservoir conditions.

[0070] Step S20: Prepare a physical model according to reservoir parameters, and test basic parameters of the physical model.

[0071] Step S30: prepare carbon dioxide and surfactant, prepare two injection pumps, one for injecting carbon dioxide gas and the other for injecting a pre-selected surfactant, and connect the injection pumps to the injector 20 of the carbon dioxide and surfactant mixing device accordingly.

[0072] Step S40: The ratio of carbon dioxide to surfactant is 5:1, and the injection rates of the surfactant and carbon dioxide are calculated.

[0073] Step S50: Control the flow rate to inject carbon dioxide gas and surfactant into the proportioning box 10 at the same time, set the environmental conditions in the proportioning box 10 (45°C, 10MPa), and the ejector injects carbon dioxide and surfactant into the primary space 11 in a preset proportion for uniform mixing. After accumulating to a certain liquid volume in the polymerizer 30, it enters the secondary space 12, and the cutting device 40 quickly cuts it to form micro-nano bubbles, and then enters the tertiary space 13 and is graded and mixed by the fusion device 50 to form a compound agent.

[0074] Step S60: After the natural cores are extracted and dried, the natural cores are arranged and loaded, and the saturation amount is recorded after they are fully saturated with formation water.

[0075] Step S70: using the prepared saturated oil sample to displace the water in the natural core, establishing the oil-water distribution of the physical model, and calculating the irreducible water saturation.

[0076] Step S80: Inject the mixed compound into the physical model through a delivery pipeline to conduct a displacement experiment of the oil reservoir. During the displacement process, record the displacement time, pump reading, injection pressure, injection speed, annular pressure and back pressure, monitor the produced gas-oil ratio and the separated oil, gas and water volumes, and organize and analyze the displacement data.

[0077] Step S90: After the experiment, the natural core is cleaned and dried, and the ratio of carbon dioxide to surfactant is changed to 3:1 and 1:1, and the above steps S40 to S80 are repeated respectively.

[0078] In the traditional method group, CO2 and DLS were mixed in a ratio of 5:1 and injected into the physical model using a horizontal flow pump under ambient conditions (45°C, 10MPa).

[0079] Implementation results analysis: According to Figure 8 It can be seen that by comparing the oil recovery efficiency of the experimental groups with different mixing ratios, the ratio of carbon dioxide to surfactant (DLS) is 3:1, followed by 1:1, and the worst is 5:1; by comparing the oil recovery efficiency of the traditional injection method and the new injection method, it is found that the oil recovery efficiency of the new method is higher than that of the traditional injection method at different time periods. At the same mixing ratio, the oil recovery efficiency of the new injection method is about 10% higher than that of the traditional injection method.

[0080] Conclusion of the embodiment: After CO2 is mixed with surfactant to displace the oil reservoir, different ratios have a certain impact on the production of the oil reservoir. Under environmental conditions (45°C, 10MPa), the ratio of CO2 to DLS is 3:1, which is most suitable for the production of heavy oil with a specific gravity of 0.88.

[0081] Changing the proportion of compound agents will have a certain impact on oil recovery efficiency, but it is not as high as the overall oil recovery efficiency of a single-ratio compound agent.

[0082] The surfactant and carbon dioxide mixing device of the present invention changes the traditional rough mixing injection method and increases the oil displacement effect without increasing the material cost.

[0083] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0084] 1. The present invention utilizes a grid-shaped ejector to form small molecules from the surfactant and carbon dioxide gas, and utilizes the polymerizer 30 to contact and mix them over a larger area, thereby increasing the contact area between gas and liquid, thereby improving the mixing effect and speed.

[0085] 2. The present invention utilizes a high-speed rotating cutting impeller 41 and a high-speed cutting device 40 to break up the bubbles of the gas-liquid mixture, and the bubbles can be broken into dozens of nanometers to several microns, and finally form micro-nano bubbles, thereby increasing the contact area between gas and liquid, so that the mixing efficiency and the number and density of bubbles can be further improved.

[0086] 3. The present invention mixes the surfactant and carbon dioxide in a funnel-shaped space in stages and stirs them to form a circulation flow in a three-dimensional space, so that the gas-liquid fluids with large differences in properties are mixed more evenly.

[0087] Obviously, the above-described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0088] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0089] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for mixing carbon dioxide and surfactant, characterized in that: include: A proportioning box (10), the proportioning box (10) comprising a primary space (11), a secondary space (12) and a tertiary space (13) which are sequentially connected along a gravity direction; a plurality of injectors (20), wherein the plurality of injectors (20) are arranged in the primary space (11), at least one of the injectors (20) is used for injecting carbon dioxide, and at least another of the injectors (20) is used for injecting a surfactant; an aggregator (30), the aggregator (30) being arranged in the primary space (11), and the aggregator (30) being located below the ejector (20), the carbon dioxide and the surfactant ejected from the ejector (20) being initially mixed above the aggregator (30) to form gas-liquid mixed bubbles, which then aggregate in the aggregator (30) and flow into the secondary space (12); a cutting device (40), the cutting device (40) being arranged in the secondary space (12), and the cutting device (40) being used to cut the gas-liquid mixed bubbles flowing into the polymerizer (30) into fine micro-nano bubbles; A fusion device (50), wherein the fusion device (50) is arranged in the tertiary space (13), and the fusion device (50) is used to fully mix the carbon dioxide and the surfactant.

2. The device for mixing carbon dioxide and surfactant according to claim 1, characterized in that: The injector (20) is a grid-shaped injector so that the injected surfactant is in the form of small bubbles.

3. The device for mixing carbon dioxide and surfactant according to claim 1, characterized in that: The polymerizer (30) has a conical polymer surface (31), the small diameter end (311) of the conical polymer surface (31) is closer to the secondary space (12) relative to the large diameter end (312) of the conical polymer surface (31), and the conical polymer surface (31) has a plurality of first outlets (313).

4. The device for mixing carbon dioxide and surfactant according to claim 3, characterized in that: The carbon dioxide and surfactant mixing device further comprises a converging plate (60), wherein the converging plate (60) is located below the cutting device (40), and the converging plate (60) has a plurality of second outlets (61), and the micro-nano bubbles in the secondary space (12) flow into the tertiary space (13) through the second outlets (61), and the first outlet (313) and the second outlet (61) are offset in the circumferential direction.

5. The device for mixing carbon dioxide and surfactant according to claim 4, characterized in that: The converging plate (60) is tapered, and the cross-sectional area of ​​the converging plate (60) gradually decreases towards the direction approaching the tertiary space (13).

6. The device for mixing carbon dioxide and surfactant according to claim 1, characterized in that: The cutting device (40) comprises: Drive device; The cutting impeller (41) is connected to the driving device to drive the cutting impeller (41) to rotate, and the cutting impeller (41) is used to cut gas-liquid mixed bubbles into fine micro-nano bubbles.

7. The device for mixing carbon dioxide and surfactant according to any one of claims 1 to 6, characterized in that: The fusion device (50) comprises a plurality of rotating blade devices (51), and the plurality of rotating blade devices (51) are arranged in intervals from top to bottom in the third-level space (13), and the rotation speeds of the rotating blade devices (51) are different.

8. The device for mixing carbon dioxide and surfactant according to claim 7, characterized in that: Among the plurality of rotating blade devices (51), the rotating blade device (51) close to the secondary space (12) has the highest rotation speed.

9. The device for mixing carbon dioxide and surfactant according to claim 7, characterized in that: The rotation speeds of the plurality of rotating blade devices (51) decrease gradually from top to bottom.

10. The device for mixing carbon dioxide and surfactant according to claim 7, characterized in that: The fusion device (50) further comprises a multi-stage variable speed planetary drive motor, and the plurality of rotating blade devices (51) are connected to the multi-stage variable speed planetary drive motor.

11. The device for mixing carbon dioxide and surfactant according to any one of claims 1 to 6, characterized in that: The proportioning box (10) is of a conical structure, and the cross-sectional area of ​​the proportioning box (10) gradually decreases from the primary space (11) to the tertiary space (13).

12. A displacement simulation method, characterized in that: The displacement simulation method adopts the carbon dioxide and surfactant mixing device according to any one of claims 1 to 11, and the displacement simulation method comprises: Step S10: configuring simulated oil of preset viscosity according to reservoir conditions; Step S20: preparing a physical model according to reservoir parameters, and testing basic parameters of the physical model; Step S30: preparing carbon dioxide and a surfactant, as well as two injection pumps, and connecting the injection pumps to the injectors (20) of the carbon dioxide and surfactant mixing device accordingly; Step S40: Calculating the preset injection rate of the carbon dioxide and the preset injection rate of the surfactant according to the ratio and the required environmental conditions; Step S50: injecting the carbon dioxide and the surfactant into the carbon dioxide and surfactant mixing device at the corresponding preset injection rate to form a compound agent after mixing; Step S60: After the natural cores are extracted and dried, the natural cores are arranged and loaded, and the saturation amount is recorded after they are fully saturated with formation water; Step S70: using the prepared saturated oil sample to displace the water in the natural core, establishing the oil-water distribution of the physical model, and calculating the irreducible water saturation; Step S80: injecting the mixed compound into the physical model through a delivery pipeline to perform a displacement experiment on the reservoir and record the displacement data; Step S90: After each group of experiments, the natural core is cleaned and dried, the ratio of carbon dioxide to surfactant is changed, and the above steps S40 to S90 are repeated until all ratio experiments are completed.

13. The displacement simulation method according to claim 12, characterized in that: In the process of injecting the mixed compound into the physical model through the delivery pipeline to conduct the displacement experiment of the oil reservoir and record the displacement data, the displacement time, pump reading, injection pressure, injection speed, annular pressure and back pressure are recorded, and the produced gas-oil ratio and the separated oil, gas and water amounts are monitored.

14. The displacement simulation method according to claim 12, characterized in that: In the process of cleaning the natural core after each set of experiments, the natural core was first cleaned with petroleum ether and anhydrous alcohol, and then blown with nitrogen.

15. The displacement simulation method according to claim 12, characterized in that: The oil-water distribution of the physical model simulates the original oil-water distribution of the formation.

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