Bentonite-water glass-activated clay plugging and channeling sealing agent

Abstract

The invention relates to a bentonite-water glass-activated clay plugging agent which comprises the following components in percentage by mass: 13-18% of bentonite, 8-12% of water glass, 3-4% of activated clay and the balance of water. The bentonite is calcium bentonite; the modulus of sodium silicate in the water glass is 3.1-3.4, SiO2 is greater than or equal to 26.0%, and Na2O is greater than or equal to 8.2%. The preparation method comprises the following steps: stirring the bentonite, the water glass, the activated clay and the water at room temperature to obtain the bentonite-water glass-activated clay plugging agent. The bentonite-water glass-activated clay plugging and channeling sealing agent is used for plugging and channeling sealing in a high-temperature gasoline injection field, meets the requirement that the temperature exceeds 200 DEG C or even reaches 300 DEG C in a high-temperature environment system, is stable, does not decompose, has good high-temperature resistance, and is very suitable for plugging and channeling sealing of a steam huff and puff well.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemicals and is mainly used for regulating, plugging and sealing oil, water and gas wells in oilfields. It relates to a bentonite-water glass-activated clay regulating, plugging and sealing agent. Background Technology

[0002] In China, heavy oil is mainly extracted using steam injection. However, most heavy oil blocks have entered the mid-to-late stages of development, characterized by high-cycle, low-pressure extraction. Due to factors such as the heterogeneity of the oil reservoirs, inter- and intra-reservoir conflicts are becoming increasingly prominent, leading to more severe steam channeling between wells. High-permeability reservoirs repeatedly absorb steam, while medium- and low-permeability reservoirs cannot be effectively utilized, resulting in wasted thermal energy and a gradual deterioration in injection efficiency. Therefore, it is urgent to implement steam injection and steam plugging measures to address these problems.

[0003] Bentonite is a commonly used particulate plugging and sealing agent in oilfields. Its advantages include low cost, good suspension, and easy injection. In particular, it significantly thickens and loses its fluidity under the influence of steam injection temperature, thus exhibiting a certain degree of plugging strength. However, this type of bentonite plugging agent has relatively low strength and is prone to disintegration under the scouring of steam or formation fluids, resulting in a short plugging life.

[0004] Currently, there are two commonly used and effective plugging and sealing agents: one is a solid-phase particle plugging and sealing agent mainly composed of bentonite and fly ash. This formulation does not have reactive curing ability, has low strength, is not resistant to erosion, and has poor plugging and sealing performance; the other is an organic polymer HPMA gel. Although it has good injection and economy, this gel has poor temperature resistance and will quickly decompose and disappear at temperatures exceeding 150°C. Therefore, it cannot meet the plugging and sealing requirements under high-temperature steam injection conditions, especially the requirements of maintaining stability, not decomposing or failing under high-temperature steam injection conditions with temperatures exceeding 200°C or even reaching 300°C. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a bentonite-water glass-activated clay blockage and sealing agent that can remain stable, without decomposition or failure, under high-temperature steam injection conditions where the temperature exceeds 200℃ or even reaches 300℃.

[0006] A bentonite-water glass-activated clay plugging and sealing agent, with the following composition by mass percentage: Bentonite 13%–18%; Water glass 8%–12%; Activated clay 3% to 4%; Water balance.

[0007] Furthermore, the bentonite is calcium-based bentonite; the sodium silicate modulus in the water glass is 3.1–3.4, SiO2 ≥ 26.0%, and Na2O ≥ 8.2%.

[0008] Furthermore, the composition by mass percentage is as follows: 18% bentonite, 12% water glass, 4% activated clay, and 66% tap water.

[0009] Furthermore, the bentonite-water glass-activated clay blockage and sealing agent is prepared as follows: Bentonite, water glass, activated clay and water are stirred at room temperature to obtain the bentonite-water glass-activated clay blockage and sealing agent.

[0010] Furthermore, the stirring time is 30 minutes.

[0011] The application of the above-mentioned bentonite-water glass-activated clay as a plugging and sealing agent in high-temperature gasoline injection fields.

[0012] Furthermore, the temperature of the high-temperature gasoline injection field is above 200°C.

[0013] Further preferably, the temperature of the high-temperature gasoline injection field is below 300°C.

[0014] This invention is the first to introduce activated clay as a gelling agent for water glass, resulting in a novel oilfield chemical for regulating plugging and sealing off seepage. Its beneficial effects are as follows: 1. Safety during construction Bentonite-water glass-activated clay plugging slurry is chemically very stable under normal temperature conditions. The release of hydrogen ions from activated clay is often slow, limited by the rate of its exchange reaction with sodium ions. Under the influence of formation temperature, the energy gained from the H+ ions is... + and Na + This allows for spontaneous exchange, preventing gelation reactions and uncontrolled phenomena such as "flash coagulation" during injection. Sufficient stabilization time is provided during and after injection, ensuring adequate injection volume and sufficient time for post-injection cleaning and tool retrieval.

[0015] 2. Adjustability of thickening and gel curing time Bentonite-water glass-activated clay plugging and sealing agent working fluid will not spontaneously gel and solidify under normal temperature and pressure ground conditions. The gelation and solidification rate of the bentonite-water glass-activated clay plugging and sealing agent slurry in the formation can be controlled by temperature and latent gelling agents. Its gelation time can be adjusted within a range of several hours. Therefore, water glass-activated clay plugging and sealing agent can fully meet the needs of plugging and sealing operations of various scales.

[0016] 3. Restoration of formation produced fluid channels The elastic gel formed after the bentonite-water glass-activated clay plugging solution solidifies will slowly release the water it contains under the influence of formation temperature, and its volume will gradually shrink, eventually forming a rigid gel. The gradual shrinkage of the gel means that the formation production channel has been restored, which precisely meets the requirements of steam injection technology for plugging and sealing agents.

[0017] 4. Good temperature resistance After the bentonite-water glass-activated clay plugging fluid undergoes a gel reaction, it initially forms an elastic inorganic gel structure. The particles in this structure are bonded together by chemical bonds, and the structure is filled with inorganic sol and a large amount of water. Under the continuous influence of the gelling agent and formation temperature, the sol particles in this gel structure gradually undergo cross-linking reactions, forming new -Si-O-Si- chemical bonds. This causes the chemical bond density in the gel to gradually increase, the average distance between particles to gradually shorten, leading to the gradual expulsion of water from the gel. The gel's volume gradually decreases, and its hardness gradually increases, eventually transforming into a rigid gel with prolonged heating. However, regardless of whether the bentonite-water glass-activated clay plugging fluid is in the gel, gel, or rigid gel stage, it does not exhibit the easily temperature-degraded characteristics of HPAM gel, even at the high temperatures of steam injection. High temperatures will not cause it to decompose or disappear. Therefore, this material has excellent high-temperature resistance and is highly suitable for plugging and sealing in steam-injection wells. Detailed Implementation

[0018] The performance of the bentonite-water glass-activated clay plugging and sealing agent of the present invention will be further explained below with reference to the embodiments.

[0019] The activated clay is produced by Liaoning Jianping Zhongyi Bentonite Co., Ltd. and is used for decolorizing oils; the bentonite is produced by Liaoning Jianping Tianzheng Mining Co., Ltd. and is calcium-based bentonite; the water glass is commercial water glass produced by Shandong Huasheng Refractory Materials Co., Ltd., with the following technical specifications: modulus 3.1-3.4, SiO2 ≥ 26.0%, Na2O ≥ 8.2%, density 1.368-1.394, water-insoluble matter ≤ 0.4%, Fe ≤ 0.05%.

[0020] The gelation time was determined by the loss of fluidity of the bentonite-water glass-activated clay plugging solution in the high-pressure sealed tank. The gel strength was determined using a SWY hydraulic universal strength tester manufactured by Handan Huayu Instrument Co., Ltd.

[0021] Example 1 The raw materials were weighed according to the following mass percentages: 13% bentonite, 8% water glass, 3% activated clay, and 76% tap water. After stirring at room temperature (25℃) for 30 minutes, the mixture was placed in a sealed container and heated at constant temperatures of 200℃, 250℃, and 300℃ respectively. The gelation times were 72h, 48h, and 36h respectively; the gel strengths were 2.15 kg / cm². 2 2.40 kg / cm 2 2.77 kg / cm 2 .

[0022] Example 2 The raw materials were weighed according to the following mass percentages: 15% bentonite, 10% water glass, 3.5% activated clay, and 71.5% tap water. After stirring at room temperature (25℃) for 30 minutes, the mixture was placed in a sealed container and heated at constant temperatures of 200℃, 250℃, and 300℃ respectively. The gelation times were 66h, 38h, and 27h respectively; the gel strengths were 2.34kg / cm². 2 2.63 kg / cm 2 2.93 kg / cm 2 .

[0023] Example 3 The raw materials were weighed according to the following mass percentages: 18% bentonite, 12% water glass, 4% activated clay, and 66% tap water. After stirring at room temperature (25℃) for 30 minutes, the mixture was placed in a sealed container and heated at constant temperatures of 200℃, 250℃, and 300℃ respectively. The gelation times were 50h, 32h, and 21h respectively; the gel strengths were 2.54kg / cm². 2 2.83 kg / cm 2 3.23 kg / cm 2 .

[0024] The preparation and injection method of the bentonite-water glass-activated clay plugging solution of the present invention: The specific preparation process of the bentonite-water glass-activated clay plugging solution is as follows: Weigh the bentonite, water glass, activated clay and water according to the formula requirements, and stir them evenly in the mixing tank.

[0025] The construction process generally employs a general injection method, utilizing the injection-production tubing within the well to inject the designed volume of bentonite-water glass-activated clay plugging fluid. This method is simple to implement, requiring no movement of the tubing; only the injection pressure and flow rate need to be controlled. This injection method leverages the heterogeneous permeability of the formation. During working fluid injection, due to the lower flow resistance in high-permeability layers, the working fluid primarily enters these layers. High-permeability layers are typically high-water-cut layers, where plugging agents are needed for sealing. Therefore, the selective injection of the bentonite-water glass-activated clay plugging fluid can be achieved by utilizing the different permeabilities of the formation. General plugging is primarily used for injection-production wells with complex conditions. During construction, the plugging objective is achieved by controlling the injection pressure and flow rate. This reduces the absorption capacity of high-permeability layers and activates the absorption capacity of low-permeability layers, thereby improving the sweep efficiency.

[0026] This invention is primarily used as a bentonite-water glass-activated clay plugging and sealing agent for heavy oil thermal recovery wells. This material is composed of bentonite, water glass, activated clay, and water. During application, it preferentially enters the high-permeability channels of the formation, gelling and solidifying into an inorganic elastic gel or rigid integral plug at formation and steam injection temperatures. This seals the flow channels, effectively blocking water flow and profile control. The main functions of the three components—bentonite, water glass, and activated clay—in this invention are as follows: (1) The role of bentonite The property of increasing the particle concentration of bentonite in suspensions prepared at high temperatures, leading to a further increase in the dispersion of bentonite flaky particles, is known as high-temperature dispersion of bentonite. The essence of high-temperature dispersion is still bentonite hydration dispersion, only that high temperatures further promote the degree of hydration dispersion. High temperatures intensify the thermal motion of bentonite mineral flaky particles and reduce water viscosity. This reduces the resistance to water molecules penetrating the bentonite crystal layers and enhances the diffusion capacity of cations on the bentonite surface, resulting in a thicker diffuse double layer, an increased zeta potential, and a further increase in the dispersion of bentonite. The higher the temperature and the longer the exposure time, the more significant the high-temperature dispersion.

[0027] High-temperature dispersion of bentonite can lead to gelation and even solidification of bentonite suspensions. Generally, when the bentonite content in a suspension reaches a certain level, the high-temperature dispersion causes the concentration of plate-like bentonite particles in the suspension to reach a critical value. At this point, closely spaced plate-like bentonite particles will connect with each other, forming a continuous network structure that fills the entire volume, i.e., forming a gel. During high-temperature gelation, if hydrated calcium silicate or hydrated calcium aluminate crystals are formed at the junctions of the bentonite plate-like particles, the bentonite gel will further solidify into a rigid structure; this is the high-temperature solidification of bentonite suspensions.

[0028] Whether a bentonite suspension gels or solidifies at high temperatures depends primarily on the following factors: bentonite type, bentonite content, pH value, temperature, and reaction time. Under otherwise identical conditions, high-temperature gelation occurs when the bentonite content increases to a certain threshold. The lowest concentration at which a bentonite suspension gels at a given temperature is typically called the capacity limit of that bentonite at that temperature. When the bentonite content is below its capacity limit, the suspension only thickens without gelling; above its capacity limit, gelation occurs. Increased bentonite content leads to more bentonite particles and shorter interparticle distances. The plate-like bentonite particles can interconnect to form a network structure, resulting in gelation and loss of fluidity. This gelation can also have a certain regulating and sealing effect on heavy oil thermal recovery wells.

[0029] When the bentonite content exceeds its capacity limit, and there is also a certain amount of Ca... 2+ Mg 2+ When cations are present and the pH value is high, bentonite gel will undergo high-temperature solidification. At this time, Ca... 2+ Mg 2+ The cations bind to the Si-O and Al-O bonds around the montmorillonite flakes, breaking them to form hydrated calcium silicate or hydrated calcium aluminate crystals. This "welds" the montmorillonite flakes together, creating a rigid structure that solidifies. This high-temperature curing reaction of bentonite is similar to the volcanic ash reaction where materials containing active silica and active alumina react with calcium hydroxide to form hydrated calcium silicate, hydrated calcium aluminate, or hydrated calcium sulfoaluminate. To ensure sufficient Ca in the plugging solution... 2+ The present invention uses calcium-based bentonite.

[0030] (2) The role of water glass Bentonite, as a type of plugging agent, has low strength and is prone to disintegration under the influence of steam or formation fluids, resulting in a short plugging lifespan. Therefore, this invention incorporates water glass, which provides structural strength.

[0031] Water glass is highly stable at room temperature and does not spontaneously undergo gelation, making it a material that can be stored stably for a long time. Water glass consists of particles smaller than 100 nm. The interior of each particle is an irregular three-dimensional network structure composed of amorphous silica (SiO2), and the particle surface is covered with silanol (-Si-OH). This invention utilizes the gel-forming chemical property of silanol to develop a novel plugging and sealing agent.

[0032] Water glass has a composition approximately Na₂O·nSiO₂·mH₂O. It is a strong base-weak acid salt and undergoes hydrolysis in the presence of water, producing free sodium hydroxide. Further ionization of sodium hydroxide makes the water glass solution alkaline. Similarly, the silica gel precipitated from the water glass due to hydrolysis can be dissolved by its own sodium hydroxide, becoming soluble silicates and ionizing to generate a series of simple and complex ions. Therefore, water glass is a complex system; its solution exhibits characteristics of both a colloidal and a solution. In this system, the colloidal nuclei at the center of the colloidal particles are aggregates of silica with strong adsorption properties. Some SiO₃⁻ ions are ionized in the colloidal solution. 2- and OH - Anions are adsorbed by the colloidal core, and at the same time, some Na+ is also adsorbed. + Ions are adsorbed on SiO3 2- and OH - The anions are surrounded by colloidal particles with diameters ranging from 1 to 100 nm. The SiO3 adsorbed by the colloidal core... 2- and OH - Ions and some of the closer Na + Ions form an adsorption layer, giving the colloidal particles a negative charge. Around the particles, a portion of Na+ with the opposite charge is also loosely adsorbed. + Ions, this part of Na + Ions form a diffusion layer. This electrostatic repulsion between water glass particles ensures that the water glass remains stable for a long time.

[0033] But it neutralizes the adsorbed OH groups. - Adding sufficient electrolytes can lower the zeta potential, reducing the repulsive force between SiO2 particles and making them more prone to collision and aggregation, thus causing the sol to coagulate. Therefore, changing the pH of the water glass solution or adding certain electrolytes can cause it to coagulate. Studies have shown that pH is the most sensitive factor affecting water glass coagulation. When the pH is >11, there is virtually no polymerization, meaning the stability is at its maximum. Conversely, as the pH decreases, the polymerization of silica sol increases. The higher the pH, the slower the polymerization rate of silica sol. Generally, the critical value for the polymerization of silica sol in alkaline water glass solution is pH 10.5. When the pH of the solution is below 10.5, the silica sol transitions to the formation of polymerized silicic acid. The lower the pH, the more intense the polymerization, meaning the lower the stability, leading to the precipitation and aggregation of the silica sol.

[0034] In this invention, the H released by the activated clay +The ions react with the NaOH generated from the hydrolysis of water glass, gradually consuming the NaOH and causing the pH of the system to gradually decrease to below 10.5. This triggers the formation of silica sol particles. The resulting silica gel particles have strong physical and chemical activity; they can adsorb with other silica gel particles and form chemical bonds between the particles, forming a milky white gel. As the reaction time increases, the amount of gel increases, the gel concentration increases, and the original emulsion gradually transforms into a gel, eventually hardening into a rigid whole.

[0035] (3) The role of activated clay The activated clay used in this invention is the commercially available activated clay commonly used for decolorization and adsorption. Activated clay is made using H... + Ions will displace the Ca in natural calcium-based bentonite. 2+ After being replaced, activated clay is generated. The reaction mechanism is: Ca 2+ -Bentonite + H₂SO₄ → 2H₂ + -Bentonite + CaSO4 Bentonite's main component, montmorillonite, is a layered aluminosilicate mineral with a 2:1 structure consisting of two Si-O tetrahedral sheets sandwiching a layer of Al-O(OH) octahedral sheets. Due to the presence of Si in the tetrahedrons... 4+ Partially by Al 3+ Substitution, Al in an octahedron 3+ Partially Mg 2+ Fe 2+ Zn 2+ The negative charge generated by displacement needs to be balanced by adsorbing exchangeable cations in the interlayer. In nature, this is mostly achieved by introducing Ca... 2+ Ions form calcium-based bentonite. When acid is mixed with calcium-based bentonite, hydrogen ions (H+) form... + This means that the hydrogen ions are exchanged into the crystalline structure of montmorillonite to form hydrogen-based bentonite, also known as activated clay. When activated clay is mixed with bentonite and water glass solution and injected into the formation, the hydrogen ions between the activated clay crystal layers... + Then react with Na in the water glass solution + The exchange process releases H from between the crystal layers. + Neutralizing sodium hydroxide in water glass lowers the pH of the system, causing the water glass gel to solidify. In this invention, the bentonite and water glass in the bentonite-water glass-activated clay plugging and sealing agent are dispersed into a stable suspension. While the water glass gels, it also fixes the bentonite sol, forming a composite. The bentonite gains structural strength and improved erosion resistance due to the fixation effect of the water glass gel. The water glass gel, with its significantly increased solid content due to the filling of bentonite, also exhibits enhanced strength and toughness. This composite material achieves a high-strength inorganic gel suitable for plugging and sealing steam wells.

[0036] The gelation and hardening mechanism of the bentonite-water glass-activated clay plugging working fluid of this invention can be simply divided into several steps: The first step: gelation and high-temperature curing of calcium-based bentonite paste; The second step: the formation of silica gel; The third step: dehydration and polymerization of silica gel, and formation of polymerized silica-bentonite composite gel; The fourth step: bond breaking at the edges of bentonite particles and the interaction of active SiO2 and Ca in the silica gel. 2+ Mg 2+ Reactions that produce hydrated calcium silicate, hydrated magnesium silicate, hydrated calcium aluminate, hydrated magnesium aluminate, etc.

[0037] The second and third steps, namely the reaction between water glass and activated clay, are the most important aspects of the innovation of this invention.

[0038] Water glass solution is an alkali metal silicate, and the hydrolysis reaction of water glass is as follows: Na2O.nSiO2+(2n+1)H2O→2Na2O+nSi(OH)4 The sodium oxide generated during the hydrolysis of water glass has a colloidal effect on the silica gel, causing it to recombine into silicates. Therefore, the hydrolysis reaction is reversible, which is conducive to the stability of water glass. In this state, the pH of the water glass aqueous solution is generally greater than 11.5. The stability of water glass varies with the pH of the solution; the higher the pH, the lower the polymerization rate of water glass. When pH > 11.5, there is practically no polymerization, meaning the stability is at its maximum. Conversely, as the pH decreases, the polymerization of water glass increases.

[0039] Water glass solutions are most stable at pH values ​​greater than 11.5 because the surface charge density and zeta potential of the water glass particles are high at this pH, and the repulsive forces between the particles dominate, preventing them from colliding and gelling, thus maintaining a stable state for a long time. When the pH value drops to 10.5, the surface charge of the particles decreases, the zeta potential decreases, and the particles are more likely to collide and gel.

[0040] Therefore, when acidic substances are present in the water glass solution, they can neutralize the NaOH generated by the hydrolysis reaction, thereby reducing the alkalinity of the solution and disrupting the stability of the water glass solution. This intensifies the polymerization process, causing silica gel to continuously precipitate and polymerize from the solution.

[0041] H in the activated clay crystal layer + Na+ ions ionize with water glass at formation temperature and high main steam temperature. + Ions undergo an exchange reaction, entering the solution from the bentonite crystal layer, and the exchanged H+... +The hydrolysis reaction occurs, and its ionic equation is: MMT-H + +Na + →MMT-Na + +H + H + +H₂O→NH₃+H₃O + When water glass solution is mixed with activated clay, acid will gradually be generated. This acid will react with the base in the water glass solution to neutralize the OH group. - +H3O + →2H2O Therefore, as the reaction continues, the alkalinity in the mixture decreases continuously, and the equilibrium shifts to the right. Thus, the function of the activated clay in this invention is: (1) Reduce the Na2O content in the mixture to prevent the precipitated silica gel from being dissolved by alkali again; (2) The stability conditions of the water glass solution are disrupted, causing silica gel to continuously precipitate and condense from the solution as the alkalinity of the mixture decreases. This leads to the continuous hydrolysis of water glass with hydrogen ions, and the reaction continues indefinitely. The overall chemical reaction can be simply represented as: Na₂O.nSiO₂ + 2MMT-H + +(n+1)H₂O→2MMT-Na + +nSi(OH)4+2H2O As the reaction time increases, the gel continuously increases, the colloidal layer around the particles thickens, and the original suspension gradually transforms into a monolithic gel containing a large amount of water. That is, after adding activated clay to the water glass solution, when the alkalinity gradually decreases to a level that easily induces the polymerization of silica gel, individual silica gel particles gradually polymerize and gel, forming a silica gel aggregate as the polymerization process continues. The unstable -Si-OH groups in the gel gradually form a stable -Si-O-Si-3-dimensional network gel structure. This structure can persist for a long time, effectively blocking formation flow channels.

[0042] Obviously, the activated clay in this invention is used to provide H₂ to neutralize the effect of sodium hydroxide in water glass. + Ions, gelling agents that solidify water glass gels, are H+ ions. + Latent donors can only release H from the crystal layers under high temperature conditions. + However, this is not possible under normal temperature conditions. This is because activated clay has a very strong adsorption capacity, strongly adsorbing H₂. + This fixes it between the crystal layers, and the active clay, due to H... + The ionic radius is very small, resulting in a small interlayer spacing of the activated clay. The van der Waals forces between the crystal layers are very strong, leading to a relatively strong interlayer bond. Under room temperature conditions, it is not easy for the crystal layers to separate, and it is not easily affected by H₂.+ Exposure of ions increases the exchange of H+. + The difficulty of ionization means that other metal cations under normal temperature conditions cannot convert H+ ions. + It cannot be exchanged between crystal layers to form water glass gel. However, like other types of bentonite, activated clay also exhibits high-temperature dispersion under high-temperature conditions. The dispersed activated clay H... + The exposure of ions reduces the resistance to ion exchange, while H+ under high temperature conditions... + H obtains sufficient energy with other metal cations. + The ionic activity increases significantly, allowing it to break free from the crystal layers and be exchanged from the clay. It then reacts with the sodium hydroxide in the water glass, causing the pH of the system to gradually decrease, ultimately leading to a gradual increase in the water glass gel and its strength.

[0043] The silica gel generated by the reaction of water glass and activated clay in this invention has strong physical and chemical activity, including adsorption activity. It can adsorb between other silica gel particles and between bentonite gel particles, forming chemical bonds between silica gel particles and bentonite gel particles. As the reaction time increases, the number of chemical bonds between silica gel and bentonite gel increases, and the two gels gradually fuse together to form a composite gel, resulting in a continuous increase in strength and gel rigidity.

[0044] Furthermore, the water glass forming gel and the SiO2 slowly generated by dehydration under continuous steam injection temperature, as described in this invention, these newly formed highly active SiO2 will react with the bentonite and Ca in the formation fluid. 2+ Mg 2+ The reaction produces crystals such as hydrated calcium silicate and hydrated magnesium silicate. These crystals can gradually enhance the strength and rigidity of the bentonite-water glass composite gel. Therefore, water glass is also a donor of active silicon, providing a large amount of active SiO2, which, together with the Ca provided by calcium-based bentonite, forms a crystalline solid. 2+ It reacts to form hydrated calcium silicate with higher strength.

[0045] The above are merely specific embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bentonite-water glass-activated clay plugging and sealing agent, characterized in that: The composition by mass percentage is as follows:

2. The bentonite-water glass-activated clay plugging and sealing agent according to claim 1, characterized in that: The bentonite is calcium-based bentonite; the sodium silicate modulus in the water glass is 3.1-3.4, SiO2 ≥ 26.0%, and Na2O ≥ 8.2%.

3. The bentonite-water glass-activated clay plugging and sealing agent according to claim 2, characterized in that: The composition by mass percentage is as follows: The composition is 18% bentonite, 12% water glass, 4% activated clay, and 66% tap water.

4. The bentonite-water glass-activated clay plugging and sealing agent according to claim 1 or 3, characterized in that: The preparation process is as follows: Bentonite, water glass, activated clay, and water are stirred at room temperature to obtain a bentonite-water glass-activated clay plugging and sealing agent.

5. The bentonite-water glass-activated clay plugging and sealing agent according to claim 4, characterized in that: When stirring, the stirring time is 30 minutes.

6. The application of a bentonite-water glass-activated clay blockage and sealing agent as described in claim 1 or claim 3 in high-temperature gasoline injection fields.

7. The application of the regulating and sealing agent according to claim 6 in high-temperature gasoline injection fields, characterized in that: The temperature of the high-temperature gasoline injection field is above 200°C.

8. The application of the regulating and sealing agent according to claim 7 in high-temperature gasoline injection fields, characterized in that: The temperature of the high-temperature gasoline injection field is below 300℃.

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