Foam flow regulating system for underground in-situ curing as well as preparation method and application of foam flow regulating system

Abstract

The invention relates to the technical field of oil and gas field development, in particular to an underground in-situ cured foam flow regulating system and a preparation method and application thereof.The foam flow regulating system is characterized in that a foaming agent, a foam stabilizer, a curing material and formation water form a foam system solution, and the curing material is composed of a curing main agent and a curing auxiliary agent; in the foam system solution, the mass fraction of the foaming agent is 0.1 wt%-1.2 wt%, the mass fraction of the foam stabilizer is 5 wt%-20 wt%, the mass fraction of the curing main agent is 10 wt%-40 wt%, the mass fraction of the curing auxiliary agent is 5 wt%-20 wt%, and the balance is formation water. According to the foam flow regulating system provided by the invention, the curing material is added into the foam system, and the high-strength porous plugging material is formed after the foam system is injected into the stratum, so that the plugging of cracks and holes is realized, and a porous structure can also be used for providing shear regeneration conditions for the subsequent foam migration process.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, in particular to an underground in-situ solidified foam flow regulating system and a preparation method and application thereof. Background Art

[0002] At present, foam technology can effectively solve the crossflow problem in water injection and gas injection development by reducing gas permeability, regulating fluidity and cleaning effect, thereby achieving the effect of improving recovery. However, due to the complex and harsh conditions of the interlaced development of large-scale fractures and pores in some formations, there is a lack of the environment required for foam generation and migration. The foam is not easy to regenerate after breaking, and the long-distance migration is very easy to separate gas and liquid, resulting in poor application of foam in this type of formation, limiting the effect of foam mobility control. In order to improve the effect of foam in formations with large-scale fractures or interlaced pores and caves, it is urgent to achieve the reconstruction of the reservoir space.

[0003] The processing methods in the prior art include the following two methods: One is to selectively solidify and seal large-scale cracks and holes by injecting plugging agents to reduce the negative impact on foam migration. For example, Chinese patent document CN 112358859 A (application number 202011245320.5) discloses a gel foam plugging agent. The gel system includes sodium alginate, tetradecyl hydroxysulfobetaine foaming agent, acrylamide monomer, NN methylenebisacrylamide cross-linking agent, tert-butyl hydroperoxide initiator and brine. When used, it is injected into the formation to form a gel to achieve temperature-resistant water plugging function; another example is Chinese patent document CN 112358860 A (application number 202011285694.X) discloses a resin foam plugging agent, which also forms resin foam after being injected into the formation to achieve a plugging effect; however, the foam plugging agent mainly focuses on high temperature resistance and foam stability, and the main effect achieved in fracture-hole formations is to plug the gas channel. The foam directly blocks the fractures or holes completely, and does not consider how to solve the problem of the connection between the subsequent displacement fluid and the displacement channel-fracture hole, resulting in a large amount of waste of underground space; The second is to provide strong shear conditions to create a suitable regeneration and migration environment for the foam and achieve effective effects on such formations. For example, Chinese patent document CN 109439300 A (application number 201811223599.X) discloses a flow regulating agent particle, which is injected into the formation and filled in the cracks and holes to form a porous medium, thereby improving the shear effect on the foam, promoting foam regeneration, and achieving the distribution position of the particles in the fracture-cavity formation by adjusting different densities. However, the sedimentation problem of the flow regulating agent particles during the migration process cannot be effectively solved. At the same time, this type of method also has the problem of too high pressure required for particle injection.

[0004] It can be seen that the existing flow regulation methods have different problems. How to take into account the advantages of the two flow regulation methods, achieve blocking without "death" and provide sufficient shear force for the subsequent injection of foam liquid, is the key to improving the effect of foam fluid. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide an underground in-situ solidified foam flow regulation system and its preparation method and application. By adding solidifying materials to the foam system and injecting them into the formation to form a high-strength porous sealing material, not only the cracks and holes can be sealed, but also the porous structure can be used to provide shear regeneration conditions for the subsequent foam migration process.

[0006] In order to achieve the above technical effects, the present invention adopts the following technical solutions: An underground in-situ solidified foam flow regulating system, comprising a foaming agent, a foam stabilizer, a solidifying material and formation water to form a foam system solution, wherein the solidifying material comprises a solidifying main agent and a solidifying auxiliary agent; In the foam system solution, the mass fraction of the foaming agent is 0.1wt%-1.2wt%, the mass fraction of the foam stabilizer is 5wt%-20wt%, the mass fraction of the curing main agent is 10wt%-40wt%, the mass fraction of the curing auxiliary agent is 5wt%-20wt%, and the balance is formation water; The foam stabilizer should be particles with a particle size less than 200 mesh; The main curing agent is industrial slag or modified clay, and the curing auxiliary agent is inorganic acid sodium salt. Among the components of the curing agent, SiO2 accounts for 19.26wt%-53.12wt%, Al2O3 accounts for 6.23wt%-15.15wt%, Fe2O3 accounts for 0.5wt%-1.63wt%, CaO accounts for 35.65wt%-60.12wt%, and MgO accounts for 8.85wt%-9.12wt%; The mineralization of formation water is 15×10 4 mg / L-25×10 4 mg / L.

[0007] The foam flow regulation system provided by the present invention adds a curing material composed of a curing main agent and a curing auxiliary agent to the foam system. After being injected into the formation, it can be cured under high temperature and high mineral conditions to form an inorganic hydrated gel material with a porous structure, thereby realizing underground in-situ curing and plugging of underground fractures and holes. At the same time, the porous structure also provides shear regeneration conditions for the migration of subsequently injected foam in the fractures and holes, thereby ensuring the effect of the foam.

[0008] Preferably, the foaming agent is selected from at least one of high-carbon fatty alcohol polyoxyethylene ether, dodecylphenol polyoxyethylene ether, sodium di(2-ethylhexyl) sulfosuccinate, sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, hydroxysulfobetaine, lauric acid diethanolamide, fatty alcohol polyoxyethylene ether sulfate or sodium carboxymethyl cellulose.

[0009] Preferably, the foam stabilizer is selected from at least one of fly ash particles, silica particles, montmorillonite, kaolin, montmorillonite, illite, attapulgite, kaolinite, sepiolite or chlorite.

[0010] Preferably, the curing aid is selected from at least one of sodium silicate, sodium aluminate or sodium phosphate.

[0011] Preferably, the underground in-situ solidified foam flow regulating system has a liquid separation half-life of 6h-24h.

[0012] The present invention also provides a method for preparing the above-mentioned underground in-situ solidified foam flow regulating system, comprising the following steps: S1. Add a foaming agent and a foam stabilizer to the formation water, and stir to obtain a mixed solution; S2. Under stirring, adding the curing agent to the mixed solution to obtain an intermediate solution; S3. After adding the curing aid to the intermediate solution and stirring, the foam flow regulating system is obtained by high-speed stirring and foaming using the Waring Blender method.

[0013] The foam flow regulation system provided by the present invention first constructs a strong and stable foam system, and improves the foaming volume and stability of the foam by modifying the foam stabilizer with a foaming agent, wherein the modified form is that the foaming agent is adsorbed on clay particles to form a synergistic stabilizer; and the synergistic adsorption of the foaming agent and the foam stabilizer at the gas-liquid interface effectively prevents the aggregation and coarsening of bubbles, thereby improving the stability of the foam; and then, using this foam system as a template, a curing material composed of a curing main agent and a curing auxiliary agent is added, and after the foam is formed and injected into the formation, the hydrated gel generated by the curing material under high temperature and high mineral conditions is wrapped to form a gel foam, which significantly improves the strength of the foam interface film. The foam stabilizer and the hydrated gel synergistically reduce the interfacial tension and improve the viscoelastic modulus, wherein the foam stabilizer improves the ability of the foam to resist deformation by increasing the viscosity of the foam base liquid, and the hydrated gel is adsorbed on the gas-liquid interface to form a high-strength foam interface film, thereby enhancing the self-repairing ability of the foam.

[0014] In a high temperature and high mineral environment, the foam is not easy to break and is retained because the synergistic effect of the foaming agent and the foam stabilizer helps stabilize the bubbles. At the same time, the curing main agent and the curing auxiliary agent form a hydrated gel, which covers the foam surface and the gaps between the foams with the foam as a template, generating a three-dimensional network structure, with the "foam stabilizer" particles as the filling skeleton. These network structures form a supporting role inside the material. At the same time, due to the nucleation and growth of the gel, the gaps gradually expand to form an open pore network. At the same time, the bubbles fuse with each other through pressure and expansion to form larger and more stable channels. This fusion of adjacent bubbles promotes the generation of connected pores, that is, the formation of porous foam materials.

[0015] The excellent carrying capacity of the foam improves the migration capacity of the system. The foam stabilizer particles are filled in the three-dimensional skeleton formed by the hydrated gel to construct a cross-linked interpenetrating network, which enhances the skeleton structure of the porous foam material, thereby forming a porous medium material with high porosity, good permeability, high strength and good toughness. Since the hydrated gel material needs to be solidified under high temperature and high mineral conditions, the foam flow regulation system provided in this application can be transported to the crack or hole area, and then solidified and sealed underground in situ, and the porous structure is used to provide shear regeneration conditions for the subsequent injection of foam migration. At the same time, the continuous phase skeleton characteristics of the porous structure are conducive to long-range compression, allowing oil and water to seep therein, thereby effectively controlling the differential seepage of oil and water.

[0016] Preferably, in step S1, the stirring speed is 1000 rpm, and the stirring time is 0.5h-2h; in step S2, the stirring speed is 600 rpm, and the stirring time is 1h-4h; in step S3, the stirring speed is 500 rpm, and the stirring time is 5min-15min; the high-speed stirring speed is 8000 rpm, and the high-speed stirring time is 2min-7min.

[0017] Preferably, in step S3, the gas condition for high-speed stirring and foaming is one of nitrogen, carbon dioxide, natural gas or air.

[0018] The present invention also provides the use of the above-mentioned underground in-situ solidified foam flow control system or the foam flow control system prepared by the above-mentioned preparation method in high-temperature formation profile control and sealing operations. Specifically, the temperature of the high-temperature formation is greater than 100°C.

[0019] Preferably, the application method is to inject 1-1.5PV of the foam flow regulation system into the formation along the injection well, then keep the well shut for 3-7 days, and then start production after the foam flow regulation system solidifies to form a porous foam material.

[0020] Preferably, the temperature range of the applicable high-temperature formation is between 100°C and 300°C.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides an underground in-situ solidified foam flow regulation system, which combines the good filling and fluidity of water-based foams with the high sealing strength and good permeability of the solidified porous foam material, and utilizes the high temperature of the reservoir and the high mineral conditions of the formation water. After being injected into the formation, a density-adjustable plugging structure can be formed in situ at the cracks or holes; specifically, the density is regulated by the concentration of the foam stabilizer particles and the gas-liquid ratio of the foam.

[0022] 2. The foam flow regulation system provided by the present invention has a rich pore structure after solidification, and can realize "transforming cracks or holes into low-permeability porous media" in fracture-hole formations. On the one hand, it can solve the differentiated seepage caused by gas-water viscosity, and on the other hand, it can solve the problem that the foam lacks mechanical shearing action in the fractures and holes and is difficult to regenerate after defoaming. The shear regeneration of the foam is achieved through the constructed porous structure, thereby increasing the foam migration depth.

[0023] 3. The foam flow regulation system of the present invention has good resistance to temperature, salt and dilution, and has a good liquid separation half-life, and can be applied to harsh underground environments with high temperature, high mineralization and high dilution.

[0024] 4. The foam flow regulation system in the present invention constructs a double cross-linked interpenetrating network through the solidification of the solidifying material and the inorganic filling components of the foam stabilizer, thereby enhancing the skeleton structure of the porous foam material; at the same time, the porous foam material absorbs water and expands, thereby enhancing the adhesion of the solidified porous foam material to the wall of the crack hole, thereby improving the filling capacity of the porous foam material.

[0025] 5. The solid plugging agent provided by the prior art is relatively hard and has a low permeability. For example, the thermosetting foam plugging agent provided in the Chinese patent document CN111826143 A (application number 201910322573.9) only leaves a permeability of 1.25 mD after plugging the sand-filled pipe with an original permeability of 1842 mD, which severely limits the pore distribution and thus the mass transfer. In contrast, the porous continuous phase skeleton of the present invention facilitates long-range compression, which allows water to seep through it, resulting in high mass diffusion rate.

[0026] 6. The foam flow regulation system in the present invention, through the solidification conditions of high temperature and high mineralization water in the formation, has the characteristics of defoaming when encountering oil, being stable when encountering water, blocking water without blocking oil, and selectively blocking high permeability layers, and accurately reaches the target holes and large cracks, thereby realizing in-situ solidification of gaps and holes. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the image of the foam system obtained in Example 1 after curing; Figure 2 is a microscopic image of the foam system obtained in Example 1 after curing; Figure 3 is the image of the foam system obtained in Example 2 after curing; Figure 4 is a microscopic image of the foam system obtained in Example 2 after curing; Figure 5 CT scan images of different parts of the porous foam material prepared in Example 3 from top to bottom, wherein labels a to f are scan images of the first 1.5 cm to the sixth 1.5 cm from the top of the porous foam material downward, respectively; Figure 6 is a diagram of the experimental device for foam displacement in Experimental Example 1; Figure 7 This is the pressure distribution in the long and thin tube of foam flooding in Experimental Example 1. DETAILED DESCRIPTION

[0028] The reagents and experimental equipment used in the embodiments, comparative examples and experimental examples of the present invention are all commercially available conventional reagents and experimental equipment. For example, the fly ash is derived from industrial waste generated during the combustion and power generation process in thermal power plants, and the modified clay is prepared by the preparation method of "salt-modified clay" (Wang Lianjun, Huang Zhonghua, Liu Xiaodong, et al. Study on the modification of bentonite. Industrial Water Treatment, 1999, (01): 11-13+47.). The sources and selections of other reagents and experimental equipment are not described in detail.

[0029] Example 1 An underground in-situ solidified foam flow regulating system, comprising a foaming agent, a foam stabilizer, a solidifying material and formation water to form a foam system solution, wherein the solidifying material comprises a solidifying main agent and a solidifying auxiliary agent; In this embodiment, in the foam system solution, the foaming agent is sodium carboxymethyl cellulose, the mass fraction of the foaming agent is 0.5wt%, the foam stabilizer is sepiolite, the mesh number of sepiolite is 400 mesh, the mass fraction of the foam stabilizer is 10wt%, the main curing agent is industrial slag, the mass fraction of the main curing agent is 20wt%, the curing aid is sodium silicate, the mass fraction of the curing aid is 10wt%, and the remainder is a mineralization degree of 21×10 4 mg / L of formation water; In this embodiment, the component contents of industrial slag are as follows: SiO2 accounts for 32.12wt%, Al2O3 accounts for 15.13wt%, Fe2O3 accounts for 1.61wt%, CaO accounts for 36.65wt%, and MgO accounts for 8.94wt%; The preparation method of the foam flow regulating system is as follows: S1. Add 0.5 g sodium carboxymethyl cellulose and 10 g sepiolite to 100 ml of formation water with a mineralization of 210,000 mg / L and stir at 1000 rpm for 1 h to obtain a mixed solution; S2. 20 g of slag was slowly added to the mixed solution obtained above while stirring, and stirring was continued at 600 rpm for 2 h to obtain an intermediate solution; S3. After adding 10 g of sodium silicate to the intermediate solution, the solution was stirred at 8000 rpm for 3 min under a nitrogen atmosphere to obtain a foam flow regulating system.

[0030] The prepared foam flow regulating system was sealed and placed in a 130°C oven for 6 h to simulate the formation solidification process, and a porous foam material such as Figure 1 As shown in the figure, the black line is the liquid level of the foam flow regulating system before curing. It can be seen that the porous foam material after curing is extremely stable at high temperature and can maintain the original volume almost unchanged; Figure 2 As shown, it can be seen from the microscopic image that its pore distribution is uniform and has good pore connectivity.

[0031] Example 2 An underground in-situ solidified foam flow regulating system, comprising a foaming agent, a foam stabilizer, a solidifying material and formation water to form a foam system solution, wherein the solidifying material comprises a solidifying main agent and a solidifying auxiliary agent; In this embodiment, in the foam system solution, the foaming agent is hydroxysulfobetaine, the mass fraction of the foaming agent is 0.3wt%, the foam stabilizer is fly ash, the mesh number of the fly ash is 400 mesh, the mass fraction of the foam stabilizer is 15wt%, the main curing agent is industrial slag, the mass fraction of the main curing agent is 20wt%, the curing aid is sodium aluminate, the mass fraction of the curing aid is 10wt%, and the remainder is a mineralization degree of 15×10 4 mg / L of formation water; In this embodiment, the component contents of industrial slag are as follows: SiO2 accounts for 32.12wt%, Al2O3 accounts for 15.13wt%, Fe2O3 accounts for 1.61wt%, CaO accounts for 36.65wt%, and MgO accounts for 8.94wt%; The preparation method of the foam flow regulating system is as follows: S1. Add 0.3 g of hydroxysulfobetaine and 15 g of fly ash to 100 ml of formation water having a mineralization degree of 150,000 mg / L and stir at 1000 rpm for 1.5 h to obtain a mixed solution; S2. 20 g of slag was slowly added to the mixed solution obtained above while stirring, and stirring was continued at 600 rpm for 2 h; S3. After adding 10 g of sodium aluminate to the above solution, the solution was stirred at 8000 rpm for 3 min under a carbon dioxide atmosphere to obtain a foam flow regulating system.

[0032] The prepared foam flow regulating system was sealed and placed in a 130°C oven for 6 h to simulate the formation solidification process, and a porous foam material such as Figure 3 As shown in the figure, the black line is the liquid level of the foam flow regulating system before curing. It can be seen that the porous foam material after curing is extremely stable at high temperature and can maintain the original volume almost unchanged; Figure 4 As shown, it can be seen from the microscopic image that its pore distribution is uniform and has good pore connectivity.

[0033] from Figure 2 and Figure 4 It can be seen that in Example 2, due to the reduction of mineralization, the hydrated gel generated by the curing main agent and the curing auxiliary agent is reduced, the stability of the foam at high temperature is reduced, the foam is coarsened and merged, the pore size of the formed cured foam is larger, and cracks exist, thereby reducing the overall strength. Compared with Example 1, the overall strength of Example 2 is smaller.

[0034] Example 3 An underground in-situ solidified foam flow regulating system, comprising a foaming agent, a foam stabilizer, a solidifying material and formation water to form a foam system solution, wherein the solidifying material comprises a solidifying main agent and a solidifying auxiliary agent; In this embodiment, in the foam system solution, the foaming agent is sodium carboxymethyl cellulose, the mass fraction of the foaming agent is 0.5wt%, the foam stabilizer is attapulgite, the mesh number of attapulgite is 400 mesh, the mass fraction of the foam stabilizer is 10wt%, the curing main agent is modified clay, the mass fraction of the curing main agent is 15wt%, the curing auxiliary agent is sodium phosphate, the mass fraction of the curing auxiliary is 8wt%, and the remainder is a mineralization degree of 25×10 4 mg / L of formation water; In this embodiment, the component contents of the modified clay are as follows: SiO2 accounts for 32.29wt%, Al2O3 accounts for 12.13wt%, Fe2O3 accounts for 0.948wt%, CaO accounts for 36.36wt%, and MgO accounts for 8.03wt%; The preparation method of the foam flow regulating system is as follows: S1. Add 0.5 g sodium carboxymethyl cellulose and 10 g attapulgite to 100 ml of formation water having a mineralization degree of 250,000 mg / L and stir at 1000 rpm for 2 h to obtain a mixed solution; S2. 15 g of modified clay was slowly added to the mixed solution obtained above while stirring, and stirring was continued at 600 rpm for 2 h; S3. After adding 8 g of sodium phosphate to the above solution, the solution was stirred at 8000 rpm for 3 min in an air atmosphere to obtain a foam flow regulating system.

[0035] The prepared foam flow regulating system was sealed and placed in a 130°C oven for 6 hours to simulate the formation solidification process, thereby obtaining a porous foam material. The porous foam material was CT scanned from top to bottom, and the scanned images were selected at intervals of 1.5 cm, such as Figure 5 As shown, Figure 5 In the figure, af are scanned images from the first 1.5 cm to the sixth 1.5 cm from the top of the porous foam material. It can be seen from the CT scan image that the foam is evenly distributed from top to bottom, and the pores of the porous foam material have good connectivity.

[0036] Example 4 A foam flow regulation system for underground in-situ solidification. The difference between this embodiment and embodiment 3 is that in the preparation method of the foam flow regulation system, the gas condition of step S3 is a natural gas atmosphere, and the other compositions and steps are the same.

[0037] Comparative Example 1 The foam plugging agent provided in this comparative example is the system provided in Example 8 of Chinese patent document CN 111526143 A.

[0038] Comparative Example 2 The plugging agent provided in this comparative example is the system provided in Example 2 of Chinese patent document CN 112358859 A.

[0039] Comparative Example 3 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that an equal mass of sodium citrate is used as a curing aid instead of sodium silicate, and other preparation methods and parameters are the same as those in Example 1.

[0040] Comparative Example 4 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that the mass fraction of the main curing agent is 15wt%, the mass fraction of the curing auxiliary agent is 10wt%, and the other preparation methods and parameters are the same as those in Example 1.

[0041] Comparative Example 5 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that the mass fraction of the main curing agent is 15wt%, the mass fraction of the curing auxiliary agent is 15wt%, and the other preparation methods and parameters are the same as those in Example 1.

[0042] Comparative Example 6 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that the mass fraction of the main curing agent is 10wt%, the mass fraction of the curing auxiliary agent is 15wt%, and the other preparation methods and parameters are the same as those in Example 1.

[0043] Comparative Example 7 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that the mass fraction of the main curing agent is 10wt%, the mass fraction of the curing auxiliary agent is 20wt%, and the other preparation methods and parameters are the same as those in Example 1.

[0044] Table 1 Curing time and compressive strength of different proportions of curing agent

[0045] According to Table 1, the curing time of Example 1 is 4.5h, and the compressive strength is 1.5MPa, which meets the design requirements. The system of Comparative Example 3 is not cured, indicating that the acid radical ions of inorganic acid salts are needed for curing, and organic acid sodium salts cannot help with curing. At the same time, as the proportion of the curing main agent decreases, the compressive strength decreases accordingly, which shows that the curing main agent mainly affects the compressive strength of the curing foam system; and as the proportion of the curing auxiliary agent increases, the curing time decreases accordingly, which shows that the curing auxiliary agent affects the curing time of the curing foam system.

[0046] Experimental Example 1 like Figure 6 As shown in the figure, the pressure at different positions during the foam flooding process was monitored by using a long thin tube displacement device, and the pressure propagation during the foam flooding process was compared; 9 pressure measuring points were evenly arranged along the seepage direction, and the long thin tube was evenly divided into 8 sections, each with a length of 37.5m. Real-time pressure collection was performed through a pressure sensor and an automatic pressure acquisition device. The system inlet pressure (P1) was controlled by an injection pump, and the outlet pressure (P9) was controlled by a back pressure valve. The experimental gas was nitrogen; the thin tube was 3m long and 12mm in diameter, and the gas and solution were injected simultaneously at a constant rate.

[0047] a. Experimental group 1: The specific steps are as follows: 1. Prepare 0.5 wt% of the YF-1 foam system and the foam flow regulating system described in Example 1 for use; 2. Fill the long and thin tube model with 80-120 mesh quartz sand, and then saturate the sand-filled long and thin tube with water; 3. Calculate the porosity of the sandstone core tube and measure its permeability with water. The permeability is 2500×10 -3 -4000×10 -3 μm², proceed to the next step of the experiment, otherwise repeat steps 2 and 3; 4. Constant temperature heating: Turn on the power switch of the thermostat and heat it to the formation temperature (130℃); 5. After the long and thin tube is preheated, first inject 1.5PV of foam flow regulation system with a gas-liquid ratio of 2:1 at a rate of 3mL / min. After the foam system solidifies for 6 hours, perform pre-water flooding of 1.5PV at a rate of 3mL / min, then inject nitrogen with a gas-liquid ratio of 2:1 and YF-1 foam 9PV at a rate of 3mL / min for foam flooding, and finally perform subsequent water flooding of 2-3PV at a rate of 3mL / min. The experimental back pressure is set to 1MPa. 6. During the experiment, the pressure acquisition device was used to record the pressure P1-P9 at different positions of the model in real time.

[0048] b. The specific steps of Experimental Group 2 differ from those of Experimental Group 1 in that the 1.5 PV foam flow regulating system is not injected in Step 5, and the other steps and parameters are the same.

[0049] like Figure 7 As shown in the figure, the pressure changes at different positions during the foam flooding process, and the pressure distribution in the horizontal axis direction reflects the pressure propagation during the foam flooding process. It can be seen from the figure that as the foam injection amount increases, the pressure at each pressure measuring point increases accordingly and gradually propagates to the outlet end. However, the pressure increase at different positions is different. The pressure increase gradually decreases from the inlet section to the outlet end of the long thin tube, and the pressure distribution decreases almost in a linear manner. Among them, experimental group 1 has already accumulated a certain pressure before the nitrogen foam is injected, indicating that the solidified foam reduces the permeability of the long thin tube and plays a certain blocking role. At the same time, the pressure of experimental group 1 is higher than that of experimental group 2 under the condition of the same foam injection amount, which reflects the shear regeneration of nitrogen foam by the solidified foam system, which improves the migration capacity of the foam, thereby increasing the pressure at different positions of the long thin tube.

[0050] Experimental Example 2 The systems provided in Examples 1 to 3 and Comparative Examples 1-2 were used to conduct a plugging sand filling pipe performance evaluation test. The plugging sand filling pipe performance evaluation test of Examples 1-3 was designed with reference to the experimental equipment and experimental method of the test example in Comparative Example 2. Since the systems in Comparative Examples 2 and 3 are mainly for medium and low permeability formations, and this application is mainly for large holes and cracks, a higher permeability is set, and only the plugging rates in Comparative Examples 2 and 3 are compared. The only difference between the experimental equipment and Experimental Example 1 is that the long thin tube is replaced with a sand filling tube with a diameter of 25 mm and a length of 60 cm.

[0051] 1. Prepare the foam flow regulating system described in Examples 1 to 3 for use; 2. Fill the sand filling tube with 80-120 mesh quartz sand, and then saturate the sand filling tube with water; 3. Calculate the porosity of the sandstone core tube and measure its permeability with water. The permeability is 3500×10 -3μm², proceed to the next step of the experiment, otherwise repeat steps 2 and 3; 4. Constant temperature heating: Turn on the power switch of the thermostat and heat it to the formation temperature (130℃); 5. After the preheating of the sand-filled pipe is completed, a foam flow control system with a gas-liquid ratio of 2:1 is injected at a rate of 3 mL / min. After the foam system solidifies for 6 hours, the permeability of the sand-filled pipe is measured. The experimental back pressure is set to 1 MPa. Table 2 Blockage data statistics

[0052] It can be seen from Table 2 that the plugging rates of Experimental Examples 1-3 are in the range of 61%-89%, while the plugging rates of Comparative Examples 1-2 are in the range of 98.53%-99.93%; this indicates that Comparative Examples 1-2 are completely blocked and cannot guarantee the subsequent migration of foam between the cracks and holes; at the same time, the plugging rate of Example 2 is poor but also within an acceptable range, indicating that a lower mineralization will reduce the plugging effect of the foam system.

[0053] Comparative Example 7 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that the proportion of sepiolite is 2.5wt%, and other preparation methods and parameters are the same as those in Example 1.

[0054] Comparative Example 8 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that the proportion of sepiolite is 5 wt %, and the other preparation methods and parameters are the same as those in Example 1.

[0055] Comparative Example 9 The foam flow regulating system provided in this comparative example is different from that in Example 1 in that the proportion of sepiolite is 7.5wt%, and the other preparation methods and parameters are the same as those in Example 1.

[0056] Take the systems provided in Examples 1 to 3 and Comparative Examples 7 to 9, and measure the liquid separation half-life after foaming. Table 3 Dialysis half-life

[0057] Since the addition of a curing agent has an effect on the liquid half-life at high temperature, only the effect of different concentrations of the foam stabilizer content on the liquid half-life that affects the foam stabilization time is measured. According to Table 2, Examples 1-3 have a liquid half-life of 8-16h, and the foam stability is good; while the liquid half-life of Comparative Example 7 in Comparative Examples 7-9 is poor, indicating that the proportion of the foam stabilizer affects the stability of the foam, and as the content of the foam stabilizer increases, the liquid half-life increases accordingly; among them, the foam stabilizer with a concentration of 10wt%, the fly ash in Example 2 has a foam stabilization time that is less than that of the sepiolite and attapulgite in Examples 1 and 3.

[0058] At the same time, different contents of foam stabilizers can change the density of the foam system, thereby increasing the migration distance of the foam-carrying curing agent in the formation.

Claims

1. An underground in-situ solidified foam flow regulating system, characterized in that: The foam system solution is composed of a foaming agent, a foam stabilizer, a solidifying material and formation water, wherein the solidifying material is composed of a solidifying main agent and a solidifying auxiliary agent; In the foam system solution, the mass fraction of the foaming agent is 0.1wt%-1.2wt%, the mass fraction of the foam stabilizer is 5wt%-20wt%, the mass fraction of the curing main agent is 10wt%-40wt%, the mass fraction of the curing auxiliary agent is 5wt%-20wt%, and the balance is formation water; The foam stabilizer should be particles with a particle size less than 200 mesh; The main curing agent is industrial slag or modified clay, and the curing auxiliary agent is inorganic acid sodium salt. Among the components of the curing agent, SiO2 accounts for 19.26wt%-53.12wt%, Al2O3 accounts for 6.23wt%-15.15wt%, Fe2O3 accounts for 0.5wt%-1.63wt%, CaO accounts for 35.65wt%-60.12wt%, and MgO accounts for 8.85wt%-9.12wt%; The mineralization of formation water is 15×10 4 mg / L-25×10 4 mg / L; The foaming agent is selected from at least one of high-carbon fatty alcohol polyoxyethylene ether, dodecylphenol polyoxyethylene ether, sodium di(2-ethylhexyl) sulfosuccinate, sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium α-olefin sulfonate, hydroxysulfobetaine, lauric acid diethanolamide, fatty alcohol polyoxyethylene ether sulfate or sodium carboxymethyl cellulose; The foam stabilizer is selected from at least one of fly ash particles, silica particles, montmorillonite, kaolin, montmorillonite, illite, attapulgite, kaolinite, sepiolite or chlorite.

2. The underground in-situ solidified foam flow regulating system according to claim 1, characterized in that: The curing aid is selected from at least one of sodium silicate, sodium aluminate or sodium phosphate.

3. The underground in-situ solidified foam flow regulating system according to claim 1, characterized in that: The liquid separation half-life of the underground in-situ solidified foam flow regulation system is 6h-24h.

4. A method for preparing an underground in-situ solidified foam flow regulating system according to any one of claims 1 to 3, characterized in that: The steps include: S1. Add a foaming agent and a foam stabilizer to the formation water, and stir to obtain a mixed solution; S2. Under stirring, adding the curing agent to the mixed solution to obtain an intermediate solution; S3. After adding the curing aid to the intermediate solution and stirring, the foam flow regulating system is obtained by high-speed stirring and foaming using the Waring Blender method.

5. The preparation method according to claim 4, characterized in that: In step S1, the stirring speed is 1000 rpm and the stirring time is 0.5 h-2 h; In step S2, the stirring speed is 600 rpm and the stirring time is 1 h-4 h; In step S3, the stirring speed is 500 rpm, and the stirring time is 5 min-15 min; the high-speed stirring speed is 8000 rpm, and the high-speed stirring time is 2 min-7 min.

6. The preparation method according to claim 4, characterized in that: In step S3, the gas condition for high-speed stirring and foaming is one of nitrogen, carbon dioxide, natural gas or air.

7. An application of an underground in-situ solidified foam flow control system in profile control and channel sealing operations in high-temperature formations, characterized in that: The underground in-situ solidified foam flow regulating system is provided by any one of claims 1 to 3, or the underground in-situ solidified foam flow regulating system is prepared by the preparation method described in any one of claims 4 to 6. The temperature of the high-temperature formation is greater than 100°C.

8. The use according to claim 7, characterized in that The application method is to inject 1-1.5PV of foam flow regulation system into the formation along the injection well, then keep the well in a coolant for 3-7 days, and then start production after the foam flow regulation system solidifies to form a porous foam material.

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