CN118217872A - A viscoelastic foam dynamic sustainable generation and injection device and its application - Google Patents

Abstract

The invention relates to the technical field of oil and gas field development, in particular to a dynamic sustainable generation and injection device for viscoelastic foam and application thereof. The device provided by the invention can continuously produce the viscoelastic foam, and can realize repeated shearing and dispersion of gas and liquid in the fluid by utilizing the internal structure of the device, so that the gas and liquid mixing degree is effectively improved, and the foam generation efficiency and the foam generation effect are obviously improved; by arranging the heating sleeve and the heat preservation layer, the stratum condition is simulated in the preparation process, experimental equipment is simplified, and experimental flow is optimized; when different types of foam are prepared, different preparation parameters are selected according to foam characteristics, on the premise of keeping stirring power, eliminating liquid stagnation areas and protecting fragile particles, the miniaturization of gas and liquid drops is promoted, and finally, a uniform and fine viscoelastic foam system is generated, so that a foundation is laid for developing a simulation experiment of the viscoelastic foam, and the smooth performance of the simulation experiment and the reliability of an experiment result are ensured.

Description

A viscoelastic foam dynamic sustainable generation and injection device and its application

Technical Field

The invention relates to the technical field of oil and gas field development, in particular to a viscoelastic foam dynamic sustainable generation and injection device and application thereof.

Background technique

As a displacement fluid, foam can effectively control the flow of water and gas and promote fluid diversion with its advantages of low density, high viscosity and low liquid content. It is an effective method to prevent cross-flow, improve sweep coefficient and reservoir recovery rate, and is also one of the commonly used plugging agents in oil fields. However, with the continuous development of oil and gas resources, the output of conventional oil and gas reservoirs can no longer meet the daily needs of society, and deep and ultra-deep oil and gas have gradually become the focus of oil field development.

Faced with the harsh formation conditions of high temperature, high pressure and high mineralization in deep and ultra-deep oil and gas reservoirs, ordinary foams are difficult to exist stably and play their effective role. For this reason, viscoelastic foams such as polymer foams, gel foams, and three-phase foams have been proposed. This type of viscoelastic foam mainly enhances the stability of the foam by increasing the viscosity of the liquid phase, thereby extending the action time of the foam underground. When conducting indoor viscoelastic foam displacement or plugging experiments, conventional foam generators are filled with glass microbeads, steel balls, etc. in steel pipes to achieve foaming based on the shear effect on gas and foam base liquid. However, for viscoelastic foams, due to the high viscosity of the foam base liquid, the foam generator is prone to blockage, weak gas-liquid shear effect, and poor foaming effect. In addition, for gel/jelly foams, the foam base liquid needs to be aged at high temperature for a period of time before it can gel. After gelation, the viscosity of the base liquid increases significantly, and the conventional shear foaming method is no longer applicable.

In order to explore the application of viscoelastic foam in formations, simulation experiments on viscoelastic foam are required. Therefore, how to effectively prepare viscoelastic foam has become the key to improving the authenticity and reliability of simulation experiments.

Taking gel foam as an example, if gel foam is pre-generated under high-speed stirring, and then placed in an intermediate container and injected into a simulated formation or core at a certain pressure, although it is theoretically feasible, in actual operation, the gel foam will be compressed in the intermediate container before entering the formation, which leads to inaccurate experimental results and cannot provide effective support for actual production. Therefore, more existing technologies consider the in-situ generation of foam during the improvement process. In order to be closer to the actual situation of the formation, Chinese patent CN111189978A (application number 202010028907.4) proposes a device for in-situ generation of high-temperature and high-pressure foam, which uses gas and liquid to form foam by high-speed shear in a porous medium of a sand-filled tube. The shear rate can be adjusted by changing the gas-liquid injection speed, and the foam quality can be changed by controlling the gas-liquid injection amount. However, for aged gel foam, not only a higher injection pressure is required, but also the sand must be frequently replaced for different experimental groups. When there are particles in the system, blockage is easy to occur, and the efficient foaming of particles, gel/jelly foams cannot be met. In order to achieve the foaming of high-viscosity foam, Chinese patent CN116519655A (application number 202310734743.0) proposes a foaming method and device under the combined action of stirring foaming and inflation foaming, which can solve the problems of difficult cleaning and particle blockage. However, this patent requires the height of the stirring paddle to be continuously adjusted according to the volume of the foam base liquid in order to foam smoothly, and the influence of the gas-liquid ratio on the foaming effect cannot be controlled. In addition, magnetic stirring is easily demagnetized under high temperature conditions, and long-term high temperature conditions will reduce the effect and service life of the magnetic stirring module. For gel/jelly after gelation, the high-viscosity and high-strength foam base liquid will increase the magnetic stirring resistance, reduce the stirring speed, and weaken the foaming effect. Therefore, even if a foam outlet is added to the patent, foam cannot be generated continuously, and the needs of efficient foaming and actual experiments of viscoelastic foam cannot be met.

Therefore, the existing foaming device cannot achieve effective continuous production of viscoelastic foam, and cannot provide formation conditions during the foam preparation process, which seriously affects the simulation experiment of viscoelastic foam and is not conducive to the promotion and application of viscoelastic foam in actual production.

Summary of the invention

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a viscoelastic foam sustainable generation and injection device and its application. By setting a variable diameter stirring paddle, the high viscosity liquid phase can be effectively stirred without affecting the generated foam. At the same time, the preparation form of injection at the lower end and extraction at the upper end is utilized to achieve the sustainable generation and injection of foam.

In order to achieve the above technical effects, the present invention adopts the following technical solutions:

A viscoelastic foam sustainable generation and injection device comprises a storage part, an injection part and a stirring part connected in sequence,

The storage unit includes a gas storage device and a liquid storage device,

The injection part includes a gas delivery pipe, a liquid delivery pipe and an injection pipe connected by a tee.

The stirring part comprises a stirring tank body, a stirring motor and a stirring shaft. The top of the stirring tank body is detachably provided with a top cover, and a sampling port is opened on the top cover. The stirring tank body is covered with a first heating jacket and a first insulation layer. The top end of the stirring shaft is fixed to the stirring motor arranged on the top cover. The stirring shaft is provided with a variable diameter spiral blade which gradually narrows from bottom to top. The diameter of the upper end of the variable diameter spiral blade is 1/4-1/2 of the diameter of the lower end of the variable diameter spiral blade, and the pitch is 1/20-1/10 of the length of the stirring shaft. A porous plate is provided on the lower side of the stirring tank body, and the porous plate is located below the variable diameter spiral blade.

The gas delivery pipe is connected to a gas storage device, the liquid delivery pipe is connected to a liquid storage device, the injection pipe enters the interior of the stirring tank body from an injection hole opened at the bottom of the stirring tank body, the injection pipe is connected to a diversion branch pipe through a diversion piece, the top of the diversion branch pipe is connected to the bottom inlet of a distributor, the distributor is located below the porous plate, and the distributor is a cavity with a liquid outlet hole at the bottom.

The viscoelastic foam sustainable generation and injection device provided by the present invention has an injection hole at the bottom of the stirring tank body and a collection port on the top cover, so that the injected gas and liquid first contact the wide part below the variable diameter spiral blade in the stirring tank body for stirring and foaming, and under the action of the fluid continuously injected below and the variable diameter spiral blade, the generated foam moves upward and is finally collected from the collection port and injected into the subsequent simulation experimental equipment. Through the variable diameter treatment of the variable diameter spiral blade, the lower wide blade provides a strong shearing effect on the fluid to achieve foaming, and the upper narrow blade provides a weaker shearing effect. While playing a certain foaming role, it ensures that the upward foam shape is not destroyed and is smoothly discharged from the collection port.

After the fluid enters the branch pipe through the injection pipe, it first enters the distributor and then enters the mixing tank body through the liquid outlet at the bottom of the distributor to achieve the first shear dispersion. During the upward movement of the fluid, the second shear dispersion is achieved when passing through the porous plate, which greatly improves the degree of gas-liquid mixing in the fluid.

Preferably, a first gear is rotatably provided on the branch pipe, a dispersing blade is provided on the top surface of the first gear, the stirring shaft extends downward through the porous plate, a second gear is provided at the bottom end of the stirring shaft, and the second gear is meshed with the first gear. The second gear is driven to rotate by the stirring shaft, and when rotating, the first gear and the dispersing blade on the top surface thereof are driven to rotate, and the dispersing blade shears the fluid from the distributor, further improving the mixing degree of gas and liquid in the fluid.

Preferably, the liquid storage device comprises a liquid storage tank and a second heating jacket and a second insulation layer disposed outside the liquid storage tank, and the liquid storage tank is also connected to a plunger pump. By disposing the second heating jacket and the second insulation layer on the liquid storage tank, in-situ aging of the foam base liquid required for preparing gel/jelly foam is achieved without the need for additional oven equipment, thus simplifying the experimental device and optimizing the experimental process.

Preferably, a flow meter and a one-way valve are provided on the gas delivery pipe. Through the cooperation of the flow meter and the plunger pump, effective control of the gas-liquid ratio during the fluid injection process is achieved.

Preferably, the stirring tank body and the top cover are made of high temperature and high pressure resistant materials.

More preferably, the outer edge of the lower end of the variable diameter spiral blade fits with the inside of the stirring tank body, which can directly scrape the residual liquid on the inner wall of the stirring tank body and promote heat transfer during heating.

Preferably, the pore density of the porous plate is 2-8 pores/cm ² .

Preferably, the liquid storage device stores a foam base liquid with a viscosity of 1-50000 mPa·s.

The present invention also provides the use of the above-mentioned viscoelastic foam dynamic sustainable generation and injection device in the preparation of foam.

Preferably, when the foam base liquid viscosity is 1-10 mPa·s, the hole density of the porous plate is 2 holes/cm ² , the density of the liquid outlet holes at the bottom of the distributor is 3 holes/cm ² , the upper end diameter of the variable diameter spiral blade is 1/4 times the lower end diameter, the pitch is 1/10 of the stirring shaft length, and the stirring speed is 1000-2000 r/min.

Preferably, when the foam base liquid viscosity is 10-1000 mPa·s, the hole density of the porous plate is 2-3 holes/cm ² , the density of the liquid outlet holes at the bottom of the distributor is 3 holes/cm ² , the upper end diameter of the variable diameter spiral blade is 1/4 times the lower end diameter, the pitch is 1/10 of the stirring shaft length, and the stirring speed is 3000-4000 r/min.

Preferably, when the foam base liquid viscosity is 1000-10000 mPa·s, the pore density of the porous plate is 3-5 pores/cm ² , the density of the liquid outlet holes at the bottom of the distributor is 4 pores/cm ² , the upper end diameter of the variable diameter spiral blade is 1/3 of the lower end diameter, the pitch is 1/15 of the stirring shaft length, and the stirring speed is 4000-6000 r/min.

Preferably, when the viscosity of the foam base liquid is 10000-50000 mPa·s, the hole density of the porous plate is 6-8 holes/cm ² , the density of the liquid outlet holes at the bottom of the distributor is 5-6 holes/cm ² , the lower end diameter of the variable diameter spiral blade is 1/2 times the upper end diameter, the pitch is 1/20 of the stirring shaft length, and the stirring speed is 6000-8000 r/min.

Preferably, when the foam is particle foam, the pore density of the porous plate is 2-4 pores/ ^cm2 , the density of the liquid outlet holes at the bottom of the distributor is 3 pores/ ^cm2 , the upper diameter of the variable diameter spiral blade is 1/3 of the lower diameter, the pitch is 1/15-1/10 of the stirring shaft length, and the stirring speed is 6000-8000r/min.

The viscosity of ordinary water-based foam base liquid is 1-10mPa·s; the viscosity of polymer foam base liquid is 10-500mPa·s, and the viscosity of gel/jelly foam base liquid is 1000-50000mPa·s (test conditions: shear rate 10s ^-1 , test temperature 20-25℃). In addition to water-based foam base liquid, other foam base liquids with higher viscosity have the following problems in the process of generating foam:

(1) Mixed problems

The gas has a low density, while the high-viscosity liquid has a high density. The increase in the density difference between the gas and liquid phases makes the gas-liquid slippage phenomenon obvious during the flow process. Gas-liquid slippage mainly refers to the phenomenon that when the gas and liquid are injected at the same speed, the gas speed exceeds the liquid speed due to the density difference during the gas-liquid two-phase flow process; that is, when flowing in the pipeline, the gas and liquid separate, resulting in the inability to mix evenly and the inability to achieve the expected foaming effect;

(2) Mixing problem

High viscosity of foam base liquid means that the density of the base liquid is also high. The shear foaming process of media such as glass beads/steel wool/sand has the disadvantages of easy blocking, difficult cleaning, high injection pressure and weak shear effect. Conventional stirring foaming has a low stirring rate and relatively short stirring blades, which cannot effectively drive the flow of liquid and effective mixing of gas and liquid. Often the gas and liquid are not evenly mixed and the foam is discharged from the system. If stirred for a long time, the shape of the generated foam will be destroyed, so it is not suitable for the foaming of viscoelastic foam.

In the device provided by the present invention, firstly, a multi-stage dispersion shearing component is used to suppress the gas diffusion rate, so as to achieve efficient dispersion and mixing of gas and liquid in the fluid; secondly, shear foaming is achieved by using long spiral blades with variable diameters. On the one hand, the foam stays in the stirring system for a long time, the shearing time is long, and the foaming effect is good. The large-diameter spiral blades at the bottom have a strong stirring effect and play a major foaming role. The small-diameter spiral blades at the top play a role in maintaining the foam state while protecting the foam shape from being destroyed. During the foaming process, even if the gas and liquid are already uniformly mixed, the possibility of gas escape is not ruled out. The continuous long spiral blades with variable diameters can stir the entire process. Even if gas escape occurs, the escaped gas will be re-mixed with the liquid under the stirring action to form foam during the upward discharge process.

Compared with the prior art, the present invention has the following beneficial effects:

1. The viscoelastic foam dynamic sustainable generation and injection device provided by the present invention can continuously produce viscoelastic foam, and utilize the internal structure of the device to achieve multiple shear dispersion of gas and liquid in the fluid, effectively improving the gas-liquid mixing degree, and significantly improving the foam generation efficiency and foam generation effect;

2. The viscoelastic foam dynamic sustainable generation and injection device provided by the present invention realizes the simulation of formation conditions during the preparation process by providing a heating jacket and a thermal insulation layer, simplifies the experimental equipment, and optimizes the experimental process;

3. According to the application of the dynamic sustainable generation and injection device of viscoelastic foam provided by the present invention, when preparing different types of foams, different preparation parameters are selected according to the foam characteristics. Under the premise of maintaining stirring power, eliminating liquid stagnant areas, and protecting fragile particles, the gas and droplet refinement is promoted, and finally a uniform and delicate viscoelastic foam system is produced, which lays the foundation for conducting simulation experiments on viscoelastic foams and ensures the smooth progress of simulation experiments and the reliability of experimental results.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a viscoelastic foam sustainable generation and injection device provided in Example 1;

FIG2 is a cross-sectional view of a stirring portion provided in Example 1;

FIG3 is a schematic diagram of the coordination of the porous plate and the branch pipe provided in Example 1;

FIG4 is a cross-sectional view of the porous plate and the branch pipe provided in Example 1;

FIG. 5 is a cross-sectional view of the branch pipe and the first gear provided in Example 1. FIG.

Among them, 1 is a one-way valve; 2 is a gas delivery pipe; 3 is a gas storage device; 4 is a second heating jacket; 5 is a liquid storage tank; 6 is a plunger pump; 7 is a stirring motor; 8 is a stirring tank body; 9 is a tee; 10 is an injection pipe; 11 is a piston; 12 is a sealing gasket; 13 is a top cover; 14 is a stainless steel cylinder outer cylinder; 15 is a first insulation layer; 16 is a first heating jacket; 17 is a stainless steel cylinder inner cylinder; 18 is a variable diameter spiral blade; 19 is a porous plate; 20 is a first gear; 21 is an upper base; 22 is a bracket; 23 is a lower base; 24 is a collection port; 25 is a thread; 26 is a stirring shaft; 27 is a branch pipe; 28 is an inlet; 29 is a distributor; 30 is a dispersion blade; 31 is a second gear.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

The reagents used in the embodiments and comparative examples are all existing commonly used commercially available reagents, and their specific sources are not described here in detail.

Example 1

A viscoelastic foam sustainable generation and injection device, as shown in FIGS. 1 to 5 , comprises a storage part, an injection part and a stirring part connected in sequence,

The storage unit includes a gas storage device 3 and a liquid storage device.

The injection part includes a gas delivery pipe 2, a liquid delivery pipe 10 and an injection pipe 28 connected by a tee 9.

The stirring part includes a stirring tank body 8, a stirring motor 7 and a stirring shaft 26. The top of the stirring tank body 8 is detachably provided with a top cover 13, and a collection port 24 is opened on the top cover 13. The stirring tank body 8 is covered with a first heating sleeve 16 and a first insulation layer 15. A stainless steel cylindrical outer cylinder 14 is also provided outside the first insulation layer 15. The inner side of the first heating sleeve 16 is a stainless steel cylindrical inner cylinder 17. The top end of the stirring shaft 26 is fixed to the stirring motor 7 arranged on the top cover 13. The stirring shaft 26 is provided with a variable diameter spiral blade 18 which gradually narrows from bottom to top. The outer edge of the lower end of the variable diameter spiral blade 18 is in contact with the inside of the stirring tank body 8, and the upper end diameter is 1/4 of the lower end diameter, and the pitch is 1/10 of the length of the stirring shaft 26. A porous plate 19 is provided on the lower side of the stirring tank body 8, and the porous plate 19 is located below the variable diameter spiral blade 18. The gas delivery pipe 2 is connected to the gas storage device 3, the liquid delivery pipe 10 is connected to the liquid storage device, the injection pipe 28 enters the inside of the stirring tank body 8 from the injection hole opened at the bottom of the stirring tank body 8, the injection pipe 28 is connected to the shunt branch pipe 27 through a shunt piece, the top of the shunt branch pipe 27 is connected to the bottom inlet of the distributor 29, the distributor 29 is located below the porous plate 19, and the distributor 29 is a cavity with a liquid outlet hole at the bottom. In this embodiment, each opening of the stirring tank body 8 is provided with a sealing gasket 12 for sealing, and the stirring tank body 8 and the top cover 13 are detachably connected through a thread 25.

The first gear 20 is rotatably provided on the branch pipe 27, and a dispersion blade 30 is provided on the top surface of the first gear 20. The stirring shaft 26 extends downward and penetrates the porous plate 19. A second gear 31 is provided at the bottom end of the stirring shaft 26, and the second gear 31 is meshed with the first gear 20. The second gear 31 is driven to rotate by the stirring shaft 26, and when rotating, the first gear 20 and the dispersion blade 30 on the top surface thereof are driven to rotate, and the dispersion blade 30 shears the fluid from the distributor 29, further improving the mixing degree of gas and liquid in the fluid.

The liquid storage device includes a liquid storage tank 5 and a second heating jacket 4 and a second insulation layer disposed outside the liquid storage tank 5. The liquid storage tank 5 is also connected to a plunger pump 6. In this embodiment, a piston 11 driven by the plunger pump 6 is disposed in the liquid storage tank 5. By arranging the second heating jacket 4 and the second insulation layer on the liquid storage tank 5, in-situ aging of the foam base liquid required for preparing gel/jelly foam is achieved without the need for additional oven equipment, thereby simplifying the experimental device and optimizing the experimental process.

The gas delivery pipe 2 is provided with a flow meter and a one-way valve 1. Through the cooperation of the flow meter and the plunger pump 6, effective control of the gas-liquid ratio during the fluid injection process is achieved.

The stirring tank body 8 and the top cover 13 are made of high temperature and high pressure resistant materials.

In this embodiment, the hole density of the porous plate 19 is 2 holes/ ^cm2 ; the density of the liquid outlet holes at the bottom of the distributor 29 is 3 holes/ ^cm2 ; as shown in FIG4 , in this embodiment, there are four branch pipes 27, four first gears 20 and four distributors 29, and five dispersing blades 30 are provided on the top surface of each first gear 20.

In this embodiment, an upper base 21 with a bracket 22 is further provided below the stirring tank body 8, and the bracket 22 is arranged on the top surface of the lower base 23 to provide support and ensure the stability of the stirring tank body 8 during the stirring process.

The above device is used in the preparation of polymer foam, wherein the foam base liquid is composed of a YF-1 surfactant aqueous solution with a mass concentration of 0.7%, and the viscosity of the foam base liquid is 5 mPa·s at 20°C and 10s ^-1 as measured by an Anton rheometer, and the gas is nitrogen. The stirring speed during the preparation process is set to 1000r/min.

The preparation method is as follows:

(1) Stir the foam base liquid and put it into the liquid storage tank 5, set the injection rate to 0.5 mL/min, connect the nitrogen gas cylinder to the device, and inject it at a rate of 1 mL/min;

(2) The stirring speed is set to 1000 r/min;

(3) Record the time from the start of injection to the production outlet to form stable and continuous foam, which is recorded as the foam stable production time T ₁ ;

(4) Place 500 mL of foam in a measuring cylinder, let it stand and start timing. The time it takes for the foam volume to reach 250 mL is the foam half-life T ₂ .

Example 2

The viscoelastic foam dynamic sustainable generation and injection device used in this embodiment is the same as that in embodiment 1.

The gel foam system used in this embodiment is (expressed in mass concentration): 0.8% YF-1 surfactant, 0.3% polyacrylamide, 0.3% organic zirconium crosslinking agent, and the rest is deionized water. The viscosity of the foam base liquid is 1462 mPa·s at 20°C and 10s ^-1 as measured by Anton rheometer, and the gas is nitrogen. The difference between the device and Example 1 is that the hole density of the porous plate is 4 holes/ ^cm2 , the density of the liquid outlet hole at the bottom of the distributor is 4 holes/ ^cm2 , the upper end diameter of the variable diameter spiral blade is 1/3 of the lower end diameter, the pitch is 1/15 of the length of the stirring shaft, and the stirring speed is 4000 r/min.

The experimental steps of this embodiment are the same as those of embodiment 1.

Example 3

The viscoelastic foam dynamic sustainable generation and injection device used in this embodiment is the same as that in embodiment 1.

The polymer foam system used in this embodiment is (expressed in mass concentration): 0.7% YF-1 surfactant, 0.3% xanthan gum, and the rest is deionized water. The viscosity of the foam base liquid is 216 mPa·s at 20°C and 10s ^-1 as measured by Anton rheometer. The gas is nitrogen. The difference between the device and Example 1 is that the hole density of the porous plate is 3 holes/cm ² , the upper end diameter of the variable diameter spiral blade is 1/4 times the lower end diameter, the pitch is 1/10 of the length of the stirring shaft, and the stirring speed is 4000 r/min.

The experimental steps of this embodiment are the same as those of embodiment 1.

Example 4

The viscoelastic foam dynamic sustainable generation and injection device used in this embodiment is the same as that in embodiment 1.

The foam system used in this embodiment is (expressed in mass concentration): 0.7% YF-1 surfactant, 10% fly ash particles, the rest is deionized water, the particle size range of the fly ash particles is 0.2-100 μm, and the gas is nitrogen. The difference between the device and Example 1 is that the upper end diameter of the variable diameter spiral blade is 1/4 times the lower end diameter, and the stirring speed is 6000 r/min.

The experimental steps of this embodiment are the same as those of embodiment 1.

Example 5

The viscoelastic foam dynamic sustainable generation and injection device used in this embodiment is the same as that in embodiment 1.

The gel foam system used in this embodiment is (expressed in mass concentration): 0.8% YF-1 surfactant, 0.6% polyacrylamide, 0.9% organic zirconium crosslinking agent, and the rest is deionized water. The viscosity of the foam base liquid is 14573.6 mPa·s at 20°C and 10s ^-1 as measured by Anton rheometer, and the gas is nitrogen. The difference between the device and Example 1 is that the hole density of the porous plate is 6 holes/ ^cm2 , the density of the liquid outlet holes at the bottom of the distributor is 5 holes/ ^cm2 , the upper end diameter of the variable diameter spiral blade is 1/3 of the lower end diameter, the pitch is 1/20 of the length of the stirring shaft, and the stirring speed is 8000 r/min.

The experimental steps of this embodiment are the same as those of embodiment 1.

Comparative Example 1

An ordinary foam generator commonly used in the laboratory (glass beads filled in a steel tube) is used to replace the stirring module in Figure 1 to generate foam. The foam generator is the foam generator provided in the journal article "Characteristics of CO ₂ foam plugging and migration: Implications for geological carbon storage and utilization infractured reservoirs" (Xu Z, Li Z, Liu Z. Separation and Purification Technology, 2022.).

The foaming system used in this comparative example is the same as that in Example 1.

The steps and injection parameters in this comparative example are the same as those in Example 1.

Comparative Example 2

The foam generating device used in this comparative example is the same as that in comparative example 1.

The polymer foam system used in this comparative example is the same as that in Example 2.

The steps and injection parameters in this comparative example are the same as those in Example 2.

Comparative Example 3

The foam generating device used in this comparative example is the same as that in comparative example 1.

The polymer foam system used in this comparative example is the same as that in Example 3.

The steps and injection parameters in this comparative example are the same as those in Example 3.

Comparative Example 4

The foam generating device used in this comparative example is different from the device used in Example 3 in that a spiral blade of equal diameter is provided on the stirring shaft, and the diameter of the spiral blade is the same as the diameter of the lower end of the variable diameter spiral blade in Example 3.

The polymer foam system used in this comparative example is the same as that in Example 3.

The steps and injection parameters in this comparative example are the same as those in Example 3.

Comparative Example 5

The foam generating device used in this comparative example is different from the device used in Example 3 in that a variable diameter spiral blade is provided on the stirring shaft, and the diameter of the upper end is 1/6 of the diameter of the lower end.

The polymer foam system used in this comparative example is the same as that in Example 3.

The steps and injection parameters in this comparative example are the same as those in Example 3.

Comparative Example 6

The foam generating device used in this comparative example is different from the device used in Example 3 in that the stirring speed is 1000 r/min.

The polymer foam system used in this comparative example is the same as that in Example 3.

The steps and injection parameters in this comparative example are the same as those in Example 3.

Comparative Example 7

The foam generating device used in this comparative example is different from the device used in Example 3 in that the pitch is 1/5 of the length of the stirring shaft.

The polymer foam system used in this comparative example is the same as that in Example 3.

The steps and injection parameters in this comparative example are the same as those in Example 3.

Comparative Example 8

The foam generating device used in this comparative example is different from the device used in Example 3 in that the hole density of the porous plate is 1 hole/cm ² .

The polymer foam system used in this comparative example is the same as that in Example 3.

The steps and injection parameters in this comparative example are the same as those in Example 3.

Comparative Example 9

The foam generating device used in this comparative example is different from the device used in Example 3 in that the density of the liquid outlet holes at the bottom of the distributor is 1 hole/cm ² .

The polymer foam system used in this comparative example is the same as that in Example 3.

The steps and injection parameters in this comparative example are the same as those in Example 3.

Comparative Example 10

The difference between the comparative example device and Example 4 is that the hole density of the porous plate is 5 holes/cm ² ; the density of the liquid outlet holes at the bottom of the distributor is 6 holes/cm ² .

The particle foam system used in this comparative example is the same as that in Example 4.

The steps and injection parameters in this comparative example are the same as those in Example 4.

Comparative Example 11

The difference between this comparative example device and Example 4 is that the pitch is 1/20 of the length of the stirring shaft.

The particle foam system used in this comparative example is the same as that in Example 4.

The steps and injection parameters in this comparative example are the same as those in Example 4.

Comparative Example 12

The foam generating device used in this comparative example is the same as that in comparative example 1.

The polymer foam system used in this comparative example is the same as that in Example 5.

The steps and injection parameters in this comparative example are the same as those in Example 5.

Table 1 Measured data of Examples 1-4 and Comparative Examples 1-11

Combined with the data in Table 1, in the process of generating foam, the stabilization time required by using an ordinary foam generator is longer than that of the present application, and during the stabilization time, there will be a phenomenon of alternating gas-liquid plugs at the outlet end. This is mainly due to the high gas diffusion rate and the insufficient shearing effect of the foam generator on the gas and liquid. When the stabilization time is reached, relatively uniform and stable foam begins to be continuously generated, and the diameter of the generated foam is larger than the foam generated by the present application. However, in the device of the present invention, foaming can be generated as soon as the gas and liquid enter, the stabilization time is short, and the generated foam is uniform and delicate. At the same time, for the same foam system under the same gas-liquid ratio, it can be seen from Table 1 that the foam generated by this patent has a higher foam half-life and stronger foam stability.

Compared with Comparative Example 2, since the foam system of Example 2 is gel foam and the foam base liquid has high viscosity, the foam base liquid is blocked in the ordinary foam generator and cannot generate foam. Due to the design of the variable diameter spiral blade, Example 2 can effectively generate gel foam.

Comparative analysis of Example 3 and Comparative Examples 4-9: In Comparative Example 4, since the upper and lower diameters of the spiral blades are equal, and the diameter of the upper blade is larger than that of Example 3, it not only interferes with the discharge of the foam at the outlet, but also destroys the morphology of the generated foam to a certain extent, resulting in a prolonged foam stability time and a decrease in the uniformity of the foam. Comparative Example 5 is the opposite of Comparative Example 4. The upper diameter of the spiral blade is smaller than that of Example 3. The foam stability time of the two is not much different. Although it does not affect the discharge of the foam at the outlet, the spiral blade with a small diameter cannot maintain the morphology of the top foam, resulting in the aggregation of some bubbles, and the generated foam is more dispersed, and the foam stability is poor. Due to the low stirring speed, the shear strength provided in Comparative Example 6 does not meet the requirements of uniform foaming, resulting in uneven stirring, and the appearance of three states of fluid: foam, liquid, and gas. Due to the larger pitch than Example 3, the stirring blades of Comparative Example 7 are sparsely distributed, and the gas-liquid mixed fluid between adjacent blades cannot be effectively sheared, and the output effect is similar to that of Comparative Example 6. The hole density of the porous plate in Comparative Example 8 is 1 hole/ ^cm2 , and the hole density of the liquid outlet hole at the bottom of the distributor in Comparative Example 9 is 1 hole/ ^cm2 , both of which weaken the gas-liquid dispersion and mixing ability of the injection part, further resulting in the fluid entering the stirring part being separated gas-liquid two phases, resulting in poor foaming effect. It can be seen from Comparative Examples 6-9 that the design of the injection part and the stirring part need to complement each other, and the relevant parameters of each component are within the relevant range of this application, so that uniform and delicate foam can be generated, and high-quality viscoelastic foam can be continuously provided for simulation experiments.

Analysis of Example 4 and Comparative Examples 10-11: Compared with Example 4, the hole density of the porous plate of Comparative Example 10 and the density of the liquid outlet holes at the bottom of the distributor are higher, and the pitch of Comparative Example 11 is small, and the stirring blades are densely distributed. Both cannot effectively produce uniform particle foam, and during the cleaning process at the end of the experiment, particle clusters were found near the distributor and the porous plate in the injection part and between the stirring blades. It can be seen that the dense hole distribution and stirring blades will cause particles to be blocked therein.

Compared with Comparative Example 12, in Example 5, since the foam system is gel foam and the foam base liquid has high viscosity, the foam base liquid is blocked in the ordinary foam generator and cannot generate foam. In Example 5, due to the design of the variable diameter spiral blade, gel foam can be effectively generated.

Example 6

A viscoelastic foam sustainable generation and injection device is used in the preparation of jelly foam, wherein the foam base liquid is composed of mass concentrations of 4.3% alkali lignin, 4% phenolic resin, 0.35% toughening agent, 0.5% foaming agent, and the remainder is deionized water. The viscosity of the foam base liquid is 30000 mPa·s at 20°C and 10s ^-1 as measured by an Anton rheometer, and the gas is nitrogen. The viscoelastic foam sustainable generation and injection device provided in Example 1 is used. The difference between the device and Example 1 is that the hole density of the porous plate is 6 holes/ ^cm2 , the density of the liquid outlet holes at the bottom of the distributor is 5 holes/ ^cm2 , the upper end diameter of the variable diameter spiral blade is 1/2 of the lower end diameter, the pitch is 1/20 of the length of the stirring shaft, and the stirring speed is 7000 r/min.

The preparation method is as follows:

(1) Mix the foam base liquid evenly and put it into the liquid storage tank. The heating temperature of the liquid storage tank is set to 100°C and the aging time is 5 hours;

(2) After aging, stop heating and inject the solution in the liquid storage tank into the device at a rate of 0.5 mL/min;

(3) Connect the nitrogen gas cylinder to the experimental device and set the injection rate to 1.0 mL/min;

(4) The stirring speed was set to 7000 r/min, the back pressure was set to 5 MPa, and the temperature of the stirring module was set to 50 °C.

Continuous, uniform and stable jelly foam can be observed at the collection outlet.

The generated gel foam was injected into the fracture test system provided in "Characteristics of CO ₂ foam plugging and migration: Implications for geological carbon storage and utilization infractured reservoirs" to conduct fracture plugging experiments, and the gel foam plugging rate was measured to be 99.1%, wherein the fracture core opening was 1.2 mm. It was proved that the gel foam provided in the embodiment can achieve a good plugging effect.

Claims (9)

1. A device for continuously generating and injecting visco-elastic foam is characterized by comprising a storage part, an injection part and a stirring part which are connected in sequence,

The storage part comprises a gas storage device and a liquid storage device,

The injection part comprises a gas conveying pipe, a liquid conveying pipe and an injection pipe which are connected by a tee joint,

The stirring part comprises a stirring tank body, a stirring motor and a stirring shaft, a top cover is detachably arranged at the top of the stirring tank body, a mining outlet is formed in the top cover, a first heating sleeve and a first heat-preserving layer are coated on the stirring tank body, the top end of the stirring shaft is fixed with the stirring motor arranged on the top cover, a variable-diameter helical blade which is gradually narrowed from bottom to top is arranged on the stirring shaft, the diameter of the upper end of the variable-diameter helical blade is 1/4-1/2 of the diameter of the lower end of the variable-diameter helical blade, the screw pitch is 1/20-1/10 of the length of the stirring shaft, a porous plate is arranged at the lower side inside the stirring tank body and is positioned below the variable-diameter helical blade,

The gas delivery pipe is connected to the gas storage device, the liquid delivery pipe is connected to the liquid storage device, the injection pipe enters the stirring tank body from the injection hole formed in the bottom of the stirring tank body, the injection pipe is connected to the branch pipe through the branch piece, the top end of the branch pipe is connected to the bottom surface inlet of the distributor, the distributor is located below the porous plate, and the distributor is a cavity with liquid outlet holes formed in the bottom.

2. The apparatus of claim 1, wherein the manifold is rotatably provided with a first gear having a top surface with dispersion blades, the stirring shaft extends downwardly through the perforated plate, and a bottom end of the stirring shaft is provided with a second gear engaged with the first gear.

3. The apparatus of claim 1, wherein the fluid reservoir comprises a fluid reservoir and a second heating jacket and a second insulating layer disposed externally thereof, the fluid reservoir further having a plunger pump coupled thereto.

4. The apparatus of claim 1, wherein the lower outer edge of the diameter-variable helical blade is adapted to fit within the tank body.

5. The apparatus for sustainable formation and injection of viscoelastic foam as claimed in claim 1 wherein the porous plate has a cell density of 2-8 cells/cm ².

6. The sustainable form and injection device of claim 1, wherein the liquid storage device stores therein a foam base liquid having a viscosity of 1-50000 mPa-s.

7. The apparatus for sustainable production and injection of viscoelastic foam as claimed in claim 1 wherein said gas delivery tube is provided with a flow meter and a one-way valve.

8. Use of a device for sustainable production and injection of viscoelastic foam as claimed in any one of claims 1 to 7 for the preparation of viscoelastic foam,

When the viscosity of the foam base liquid is 10-1000 mPa.s, the density of holes of the porous plate is 2-3 holes/cm ², the density of liquid outlet holes at the bottom of the distributor is 3 holes/cm ², the diameter of the upper end of the variable-diameter helical blade is 1/4 times that of the lower end, the pitch is 1/10 of the length of the stirring shaft, and the stirring speed is 3000-4000r/min;

when the viscosity of the foam base liquid is 1000-10000 mPa.s, the density of holes of the porous plate is 3-5 holes/cm ², the density of liquid outlet holes at the bottom of the distributor is 4 holes/cm ², the diameter of the upper end of the variable-diameter helical blade is 1/3 of the diameter of the lower end, the screw pitch is 1/15 of the length of the stirring shaft, and the stirring speed is 4000-6000r/min;

When the viscosity of the foam base liquid is 10000-50000 mPa.s, the density of holes of the porous plate is 6-8 holes/cm ², the density of liquid outlet holes at the bottom of the distributor is 5-6 holes/cm ², the diameter of the lower end of the variable-diameter helical blade is 1/2 times of the diameter of the upper end, the pitch is 1/20 of the length of the stirring shaft, and the stirring speed is 6000-8000r/min.

9. The use according to claim 8, wherein when the foam is a granular foam, the porous plate has a cell density of 2-4 cells/cm ², the distributor bottom has a cell density of 3 cells/cm ², the diameter of the upper end of the variable diameter helical blade is 1/3 of the diameter of the lower end, the pitch is 1/15-1/10 of the length of the stirring shaft, and the stirring speed is 6000-8000r/min.