Inorganic composite high-strength oil-water well water shutoff material and preparation method thereof

Abstract

The invention provides an inorganic composite high-strength oil-water well water shutoff material and a preparation method thereof, and belongs to the technical field of oilfield chemical agents. The material is prepared from the following raw materials in percentage by weight: 15%-20% of a high-activity mineral admixture, 2%-8% of high-performance silicate, 3%-5% of an agriculture and forestry biomass material with the particle size of 1-10 microns, 5%-8% of a suspending agent, 0.5%-0.7% of a dispersing agent, 0.04%-0.05% of a retarder, 1%-2% of a reinforcing agent, itaconic acid modified acrylate, a pH regulator and the balance of water. The preparation method comprises a step-by-step mixing and stirring process. According to the invention, 3-5% of waste agricultural and forestry biomass is utilized, through the synergistic effect of all the components, the prepared water plugging material has the advantages of high compressive strength (1.79 MPa), controllable curing time (24-48 hours), good slurry stability, high temperature resistance (greater than or equal to 140 DEG C) and the like, unification of waste recycling and high-performance water plugging materials is realized, and the water plugging material is especially suitable for water plugging operation of high-temperature fractured reservoirs.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil field chemicals, in particular to an inorganic composite high-strength water plugging material for oil and water wells and a preparation method thereof. BACKGROUND

[0002] In the later stage of oil field development, water channeling problems often occur in oil wells, which seriously affect the oil recovery rate. Using water plugging materials to plug high permeability layers or cracks is a key means to solve this problem. The commonly used water plugging materials at present mainly include organic polymers and inorganic cements.

[0003] Although the organic polymer plugging agent (such as polyacrylamide) has low initial viscosity and is easy to pump, it is prone to degradation in high temperature (>120℃) and high salt reservoir environments, resulting in plugging failure, and the cost is relatively high, and some products may decompose and produce harmful substances at high temperatures. Although the inorganic plugging agent (such as cement slurry) has high strength and good temperature resistance, it generally has the problems of high brittleness, easy to produce shrinkage cracks, weak adhesion to the formation rock, poor stability of the slurry and easy to settle.

[0004] On the other hand, China's agricultural and forestry biomass resources (such as rice husk and straw) are extremely rich, with an annual output of about 700 million tons. At present, a large amount of agricultural and forestry waste is incinerated or landfilled, which not only wastes resources, but also causes serious environmental pollution. Although there are utilization methods such as anaerobic fermentation to produce biogas, there are problems such as low efficiency, insufficient utilization rate of cellulose, and difficulty in treating biogas slurry and residue. Therefore, it is crucial to develop high-value utilization methods for agricultural and forestry biomass.

[0005] The prior art has not effectively realized the synergy of high-value utilization of agricultural and forestry biomass and performance improvement of inorganic plugging agent. Therefore, it is urgent to develop a new type of water plugging material with low cost, environmental friendliness, high temperature and pressure resistance, and high strength and good construction performance. SUMMARY

[0006] The present application aims to solve at least one of the technical problems existing in the prior art, and provides an inorganic composite high-strength water plugging material for oil and water wells and a preparation method thereof. The purpose of the present application is to solve a series of problems such as poor environmental adaptability and strong resource dependence of traditional materials, and to promote the deep integration of technology between the biomass industry and the field of water plugging for oil and water wells.

[0007] The present application provides an inorganic composite high-strength water plugging material for oil and water wells, which is made of the following raw materials by weight percentage:

[0008] High-activity mineral admixture 15%~20%, high-performance silicate 2%~8%, agricultural and forestry biomass material 3%~5%, suspending agent 5%~8%, dispersing agent 0.5%~0.7%, retarder 0.04%~0.05%, reinforcing agent 1%~2%, itaconic acid modified acrylate 1%~2%, pH regulator and water.

[0009] Preferably, the specific surface area of the high-activity mineral admixture is 400~450 m² / kg, and the high-activity mineral admixture is composed of the following components in mass percentage: calcium oxide 40%~55%, silicon dioxide 30%~45%, aluminum oxide 10%~20%, magnesium oxide 10%~20%, manganese oxide 0.5%~1%, ferrous oxide 0.5%~1%.

[0010] Preferably, the agricultural and forestry biomass material is rice husk and / or straw powder mechanically ground to a particle size of 1~10 μm; and / or, the reinforcing agent is composed of the following components in mass percentage: lime 30%~50%, calcium carbonate 30%~40%, and the balance is calcium chloride, and the particle size of the reinforcing agent is 3~10 μm.

[0011] Preferably, the dispersing agent is composed of the following components in mass percentage: lignin sulfonate 30%~40%, sodium polyphosphate 10%~30%, and the balance is sodium dodecyl sulfonate; and / or, the retarder is composed of the following components in mass percentage: salicylic acid 20%~30%, tannic acid 30%~40%, and the balance is polymethacrylate.

[0012] Preferably, the suspending agent is composed of the following components in mass percentage: silicon dioxide 40%~60%, aluminum oxide 20%~30%, magnesium oxide 10%~20%, iron oxide 1%~5%, and the balance is fly ash; and / or, the pH regulator is composed of the following components in mass percentage: sodium carbonate 60%~75%, sodium bicarbonate 20%~35%, and the balance is sodium hydroxide.

[0013] Preferably, the reinforcing agent is composed of the following raw materials in mass fraction: lime 30%~50%, calcium carbonate 30%~40%, and the balance is calcium chloride.

[0014] Preferably, the itaconic acid modified acrylate is prepared by the following method:

[0015] The itaconic acid is dissolved in deionized water, a reflux device is built, and after stirring uniformly, it is added to a polymerization reactor, and nitrogen is introduced for 10 min to remove air in the reaction system, and nitrogen is uninterruptedly introduced during the whole polymerization process, so that the reaction is carried out under nitrogen protection;

[0016] The temperature of the reaction liquid is heated to reflux temperature under stirring;

[0017] The mixture of the acrylate monomer and the initiator is added dropwise, and the reaction is continued for 1h to ensure that the reaction is fully carried out.

[0018] After the reaction is completed, the reaction solution is cooled to room temperature, and after precipitation, filtration, washing and drying, the itaconic acid modified acrylate is obtained.

[0019] The application also provides a method for preparing the inorganic composite high-strength water plugging material for oil and water wells.

[0020] S1, adding a pH regulator, a suspending agent, a retarding agent, an agricultural and forestry biomass material, and an itaconic acid modified acrylate into water, and stirring to obtain a mixture a;

[0021] S2, adding a dispersing agent and a high-performance silicate to the mixture a obtained in step S1, and stirring to obtain a mixture b;

[0022] S3, uniformly mixing a high-activity mineral admixture and a reinforcing agent to obtain a mixture c;

[0023] S4, adding the mixture c obtained in step S3 to the mixture b obtained in step S2, and stirring to obtain the water plugging material.

[0024] Preferably, the stirring speed in step S1 is 400-600r / min, and the stirring time is 10-20min; the stirring speed in step S2 is 400-600r / min, and the stirring time is 10-20min; and the stirring speed in step S4 is 500-700r / min, and the stirring time is 10-20min.

[0025] Preferably, the stirring speed in step S1 is 500r / min, and the stirring time is 15min; the stirring speed in step S2 is 500r / min, and the stirring time is 15min; and the stirring speed in step S4 is 600r / min, and the stirring time is 15min.

[0026] Preferably, the agricultural and forestry biomass material is prepared by the following method:

[0027] After the agricultural and forestry waste raw materials such as rice husks and straws are cleaned and dried, the biomass raw materials are crushed by a crusher, and then the uniformly granulated particles of 30 mesh are screened out by a vibrating screen;

[0028] The uniformly granulated particles of 30 mesh that are preliminarily screened are placed in a Raymond mill, the rotating speed is controlled, and the treatment is repeated for multiple times until the diameter of the raw materials reaches the level of 1-10μm.

[0029] This invention provides an inorganic composite high-strength oil and water well plugging material and its preparation method. Addressing the common problems of existing oil and water well plugging materials, such as poor toughness, susceptibility to shrinkage cracks, weak adhesion to the matrix, high cost, and environmental unfriendliness, this invention provides an agricultural and forestry biomass-inorganic composite high-strength oil and water well plugging material and its preparation method. This material aims to utilize waste agricultural and forestry biomass to achieve resource utilization, while simultaneously obtaining a green oil and water well plugging material that combines high strength, high toughness, excellent impermeability, and durability. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart illustrating a method for preparing an inorganic composite high-strength oil-water well plugging material according to an embodiment of the present invention.

[0031] Figure 2 This is a comparison chart showing the results of measuring the suspension performance of the method provided in the embodiments of the present invention. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solutions of the present invention, exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0033] Where there is no conflict, the various embodiments of the present invention and the features thereof may be combined with each other.

[0034] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0035] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0036] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0037] In the existing technical system, the high-value utilization of agricultural and forestry biomass and the improvement of inorganic material performance have not yet achieved effective synergy. Specifically, the current application of organic water shutoff agent has several problems: first, its cost is relatively high; second, under high temperature and high salt environmental conditions, the water shutoff agent is prone to degradation; third, certain types of organic water shutoff agent may decompose and produce harmful substances under high temperature conditions.

[0038] To solve at least one of the technical problems existing in the related art, the present application provides an inorganic composite high-strength oil-water well water shutoff material made of the following raw materials by weight: high-activity mineral admixture 15-20%, high-performance silicate 2-8%, agricultural and forestry biomass material 3-5%, suspending agent 5-8%, dispersing agent 0.5-0.7%, retarder 0.04-0.05%, reinforcing agent 1-2%, itaconic acid modified acrylic ester 2%, pH adjuster, and the balance is water. The water shutoff material obtained by the above formula can adapt to an environment with a well depth temperature of 140°C or higher.

[0039] The reinforcing agent is composed of the following raw materials by mass fraction: lime 30-50%, calcium carbonate 30-40%, and the balance is calcium chloride. The particle size of the reinforcing agent is 3-10 μm. The reinforcing agent is used to enhance the compressive strength of the plugging agent to ensure the plugging effect at the deep part of the reservoir.

[0040] The dispersing agent is composed of the following raw materials by mass fraction: lignin sulfonate 30-40%, sodium polyphosphate 10-30%, and the balance is sodium dodecyl sulfonate. The dispersing agent is used to increase the dispersion effect of the high-activity mineral admixture and the biomass, reduce the agglomeration and caking caused by the agglomeration, and thus reduce the plugging strength and affect the plugging effect.

[0041] The retarder is composed of the following raw materials by mass fraction: salicylic acid 20-30%, tannic acid 30-40%, and the balance is polymethacrylate. The retarder is used to increase the curing time of the plugging agent, so that the plugging agent can be injected into a deeper position in the reservoir, increase the plugging effect at the distal end of the reservoir, and ensure the effectiveness of the implementation.

[0042] The suspending agent is composed of the following raw materials in mass fraction: 40-60% of silicon dioxide, 20-30% of aluminum oxide, 10-20% of magnesium oxide, 1-5% of iron oxide, and the balance of fly ash.

[0043] The pH regulator is composed of the following raw materials in mass fraction: 60-75% of sodium carbonate, 20-35% of sodium bicarbonate, and the balance of sodium hydroxide.

[0044] The material aims to utilize abandoned agricultural and forestry biomass to realize resource utilization, and simultaneously obtain a green water plugging material for oil wells with high strength, high toughness, excellent impermeability and durability.

[0045] The composite plugging agent prepared from the material has a density of 1.12-1.23 g / cm3, a viscosity of , a curing time of 24-48 h, and a compressive strength of 1.7-2.1 MPa. The composite plugging agent can solve the problems of poor pumpability and low strength of conventional inorganic plugging agents, and can solve the problem of difficult plugging of fissure flow in oil reservoirs, and can meet the needs of water plugging in fissure-type oil reservoirs with a temperature of more than 140 DEG C.

[0046] As another embodiment of the present application, the high-activity mineral admixture has a specific surface area of 400-450 m2 / kg and is composed of the following components in mass percentage: 40-55% of calcium oxide, 30-45% of silicon dioxide, 10-20% of aluminum oxide, 10-20% of magnesium oxide, 0.5-1% of manganese oxide, and 0.5-1% of ferrous oxide. 2 ·kg -1 .

[0047] Under high temperature and high pressure, SiO2 and Al2O3 in the high-activity mineral admixture are adsorbed on the surface of the formation rock through van der Waals force to form a dense packing structure. + The high hardness (Mohs hardness 5-6) can resist water flow scouring, and the porous structure (such as slag wool) locks water through capillary action. 2+ After water is encountered, the hydration of interlayer cations causes the expansion of crystal layers to form a gel-like barrier. 3- The PO4 2+ groups in the dispersant react with Ca 2+ / Mg 3-The tetrahedral structure of the four is connected by P-O-P bridge metal ions, forming a chain or ring polymer, increasing the strength; high performance silicate hydrolysis to generate silicic acid (H2SiO3), further with Ca 2+ / Mg 2+ Reaction to generate insoluble calcium / magnesium silicate precipitate. SiO4 4- Tetrahedron through oxygen bridge (Si-O-Si) and metal ions, forming a three-dimensional network structure; retarder phenolic hydroxyl and carboxyl (-COOH) and metal ions (Ca 2+ , Mg 2+ , etc.) crosslinking to form a coordination bond, C=O double bond in the carboxyl group and metal ions form a coordination bond, phenolic hydroxyl through hydrogen bonding to enhance the intermolecular forces, inhibit the precipitation reaction of metal ions; agricultural biomass contains a large number of hydroxyl groups (-OH), which can be adsorbed by hydrogen bonding and van der Waals force with the formation of hydrogen bonds between the hydroxyl groups on the cellulose molecular chain and Si-O / Al-O groups, enhancing the adhesion, at high temperature, biomass degradation produces organic acids can react with calcium and magnesium ions to generate precipitate, enhance the strength of the blocking agent.

[0048] Further itaconic acid modified acrylic acid ester in itaconic acid -COOH can increase its solubility in water, and in alkaline conditions -COOR hydrolysis, a large number of -COO - , further Ca 2+ Reaction with carboxyl -COO - New material Ca(COOR)2, it is worth noting that the carboxyl group from different polyester chain, and the same Ca 2+ Connect two carboxyl groups, because the system produces a large number of Ca 2+ And -COO - A large number of itaconic acid modified acrylic acid ester chain through Ca 2+ Connection, forming a crosslinked network structure of organic and inorganic material composition.

[0049] As another embodiment of the present application, the agricultural and forestry biomass material is prepared by the following method:

[0050] The agricultural and forestry waste raw materials such as rice husk and straw are washed and dried, and then the biomass raw materials are crushed by a crusher, and then the uniform particles of 30 mesh are screened out by a vibrating screen, which is beneficial to control the discharge particle size during mechanical activation.

[0051] The uniformly screened biomass particles of 30 mesh are placed in a Raymond mill, the rotating speed is controlled, and repeated processing is carried out until the diameter of the raw materials reaches 1-10 μm.

[0052] Reference Figure 1As another embodiment of the present application, the present application further provides a preparation method of the water plugging material, comprising the following steps: S1, adding a pH regulator, a suspending agent, a retarding agent, a forest and agricultural biomass material and a itaconic acid modified acrylate into water, stirring at a speed of 500 r / min for 15 min to obtain a mixed solution a; S2, adding a dispersing agent and a high-performance silicate into the mixed solution a obtained in the step S1, stirring at a speed of 500 r / min for 15 min to obtain a mixture b; S3, uniformly mixing a high-activity mineral admixture and a reinforcing agent to obtain a mixture c; S4, adding the mixture c obtained in the step S3 into the mixture b obtained in the step S2, stirring at a speed of 600 r / min for 15 min, and the water plugging material is obtained, and the performance index is as follows: a density of 1.12-1.23 g / cm 3 , a viscosity , a curing time of 24-48 h, and a compressive strength of 1.7-2.1 MPa.

[0053] The mechanism of action is as follows: after the slurry is pumped into the formation fracture, the suspending agent and the dispersing agent in the slurry ensure that the particles are stably suspended and do not settle. The retarding agent controls the speed of the curing reaction, allowing the slurry to enter deeper formations. With the passage of time and the action of temperature, the high-performance silicate and the high-activity mineral admixture undergo hydration reactions to generate network-like gels and crystalline products with the calcium ions provided by the reinforcing agent. At the same time, the micron-sized forest and agricultural biomass particles not only bind to the inorganic network and the rock surface through hydroxyl groups and other groups, but also participate in the reaction through their high-temperature degradation products, further enhancing the structure. Finally, a dense, high-strength, and firmly bonded composite is formed, effectively sealing the water flow channels.

[0054] In a further aspect, the itaconic acid modified acrylate is prepared by the following method:

[0055] The itaconic acid is dissolved in deionized water, a reflux device is set up, and after stirring uniformly, it is added to a polymerization reactor, and nitrogen is introduced for 10 min to remove air in the reaction system, and nitrogen is continuously introduced during the whole polymerization process, so that the reaction is carried out under the protection of nitrogen all the time;

[0056] The temperature of the reaction liquid is heated to the reflux temperature under stirring;

[0057] The mixed solution of the acrylate monomer and the initiator is added dropwise, and the reaction is continued for 1 h to ensure that the reaction is fully carried out;

[0058] After the reaction is completed, the reaction liquid is cooled to room temperature, and after precipitation, filtration, washing and drying, the itaconic acid modified acrylate is obtained.

[0059] According to the water plugging material and the preparation method of the present application, the following comparative effects of the material are compared and explained by using 7 examples and 6 comparative examples, and the specific proportions (weight percentage) shown in Table 1 are strictly followed according to the preparation method shown in the above Figure 1 The 7 kinds of water plugging materials are prepared as follows:

[0060] Example 1: The water plugging material is made of the following raw materials in mass percentage: high-activity mineral admixture 20%, high-performance silicate 2%, agricultural and forestry biomass material 3%, suspending agent 8%, dispersing agent 0.5%, retarder 0.05%, reinforcing agent 2%, itaconic acid modified acrylate 2%, pH adjuster, and the rest is water.

[0061] The particle size of the high-activity mineral admixture is 5-30 μm. The particle size of the agricultural and forestry biomass material is 1-10 μm. The reinforcing agent is composed of the following raw materials in mass percentage: lime 30%, calcium carbonate 30%, and the rest is calcium chloride. The particle size of the reinforcing agent is 5-13 μm. The dispersing agent is composed of the following raw materials in mass percentage: lignin sulfonate 40%, sodium polyphosphate 10%, and the rest is sodium dodecyl sulfonate. The retarder is composed of the following raw materials in mass percentage: salicylic acid 20%, tannic acid 30%, and the rest is polymethacrylate. The suspending agent is composed of the following raw materials in mass percentage: silicon dioxide 40-60%, aluminum oxide 20-30%, magnesium oxide 10-20%, iron oxide 1-5%, and the rest is fly ash. The activator is composed of the following raw materials in mass percentage: sodium carbonate 75%, sodium bicarbonate 20%, and the rest is sodium hydroxide.

[0062] The preparation method of the present example is as follows:

[0063] S1, the pH adjuster, suspending agent, retarder, agricultural and forestry biomass, and itaconic acid modified acrylate are added to water, and stirred at a speed of 500 r / min for 15 min to obtain a mixed solution a;

[0064] S2, the dispersing agent and high-performance silicate are added to the mixed solution a obtained in S1, and stirred at a speed of 500 r / min for 15 min to obtain a mixture b;

[0065] S3, the high-activity mineral admixture and reinforcing agent are mixed uniformly to obtain a mixture c;

[0066] S4, the mixture c obtained in S3 is added to the mixture b obtained in S2, and stirred at a speed of 600 r / min for 15 min to obtain an agricultural and forestry biomass-inorganic composite high-strength oil and water well plugging material.

[0067] Example 2: High activity mineral admixture 15%, high performance Portland cement 2%, agroforestry biomass material 3%, suspending agent 8%, dispersing agent 0.5%, retarder 0.05%, reinforcing agent 2%, itaconic acid modified acrylate 2%, pH adjuster, and the balance is water. The rest is the same as Example 1.

[0068] Example 3: High activity mineral admixture 15%, high performance Portland cement 2%, agroforestry biomass material 3%, suspending agent 4%, dispersing agent 0.5%, retarder 0.05%, reinforcing agent 2%, itaconic acid modified acrylate 2%, pH adjuster, and the balance is water. The rest is the same as Example 1.

[0069] Example 4: High activity mineral admixture 15%, high performance Portland cement 4%, agroforestry biomass material 3%, suspending agent 8%, dispersing agent 0.5%, retarder 0.05%, reinforcing agent 2%, itaconic acid modified acrylate 2%, pH adjuster, and the balance is water. The rest is the same as Example 1.

[0070] Example 5: High activity mineral admixture 15%, high performance Portland cement 2%, agroforestry biomass material 6%, suspending agent 8%, dispersing agent 0.5%, retarder 0.05%, reinforcing agent 2%, itaconic acid modified acrylate 2%, pH adjuster, and the balance is water. The rest is the same as Example 1.

[0071] Example 6: The raw material composition of the active mineral admixture is adjusted to be: calcium oxide 0%, silicon dioxide 30%~45%, aluminum oxide 10%~20%, magnesium oxide 10%~20%, manganese oxide 0.5%~1%, ferrous oxide 0.5%~1%, etc. The rest is the same as Example 1.

[0072] Example 7: The raw material composition of the reinforcing agent is adjusted to be: a mixture of lime and calcium chloride. The rest is the same as Example 1.

[0073] Comparative Example 1: The difference from Example 1 is only that the agroforestry biomass material is not included.

[0074] Comparative Example 2: The difference from Example 1 is only that the suspending agent is not included.

[0075] Comparative Example 3: The difference from Example 1 is only that the retarder is not added.

[0076] Comparative Example 4: The difference from Example 1 is only that the pH adjuster is not added.

[0077] Comparative Example 5: The difference from Example 1 is only that the high performance Portland cement is not added.

[0078] Comparative Example 6: The difference from Example 1 is only that the dispersing agent is not added.

[0079] Comparative Example 7: The oil-water well plugging material of the agricultural and forestry biomass-inorganic composite high strength was synthesized according to the preparation method provided in Example 1, except that itallic acid modified acrylate was not added.

[0080] The compressive strength and curing time of the composite profile control and plugging agents of Examples 1-7 and Comparative Examples 1-7 were determined according to the method for evaluating the performance of profile control agents in SY / T5590-2004.

[0081] The further curing time test method was as follows: the prepared composite oil-water well plugging material mixture was stirred uniformly and poured into a 2050 mm mold, and placed in a 140℃ environment for curing. Every 3 hours, the cured sample was taken out and tested with a test needle. The time when the test needle could not sink into the sample was the curing time.

[0082] The further compressive strength test method was as follows: a regularly calibrated pressure testing machine was used, and the center of the test piece was aligned with the pressure head during operation, and the loading rate was uniform. Too fast or too slow loading rate would cause deviation of the results. After a group of experiments, abnormal values were removed, and the average value was taken as the result.

[0083] Table 1: Compressive strength and curing time of the plugging material

[0084]

[0085] As can be seen from the property test results of the composite profile control and plugging agents in Table 1, with the increase of the amount of high-activity mineral admixture in the system, the compressive strength showed an increasing trend, and the highest compressive strength was 1.74 MPa. With the decrease of the content of calcium oxide in the high-activity mineral admixture, the compressive strength also decreased. The content of calcium carbonate in the reinforcing agent also affected the compressive strength of the composite plugging agent. When no calcium carbonate was added, the compressive strength of the composite plugging agent decreased significantly.

[0086] Taking the composite plugging agents prepared in Examples 2, 4 and Comparative Example 5, with the increase of the amount of high-performance silicate, the compressive strength of the composite plugging agent first increased and then decreased, and reached the maximum value at 2% addition amount. The curing time increased.

[0087] Taking the composite plugging agents prepared in Examples 1-7 and Comparative Example 1, the compressive strength of the plugging material without the addition of agricultural and forestry biomass was 1.01 MPa. With the increase of the proportion of agricultural and forestry biomass, the compressive strength after curing also increased, and when the addition amount was 6%, the compressive strength could reach more than 1.79 MPa.

[0088] Taking the composite plugging agents prepared in Examples 1-7 and Comparative Example 3, the curing time of the plugging material without the addition of a retarder was significantly reduced. The addition amount of the retarder had little effect on the compressive strength of the composite plugging agent system.

[0089] Take the composite plugging agent prepared in Examples 1-7 and Comparative Example 4, the consolidation time of the water plugging material is increased without adding a pH adjuster, and the amount of the retarder has little effect on the compressive strength of the composite water plugging agent system.

[0090] Take the composite plugging agent prepared in Examples 1-7 and Comparative Example 7, the compressive strength of the composite profile control agent is significantly reduced without adding itaconic acid-modified acrylate.

[0091] Figure 2 The results of the determination of the suspensibility of the water plugging materials prepared in Examples 1-7 and Comparative Examples 2 and 6 are as follows: the water separation rates of the water plugging materials prepared in Examples 1-7 within 12 h are 3.6%, 4.5%, 5.7%, 5.1%, and 2.7%, compared with Comparative Example 2, the present application enhances the crosslinking ability of the water plugging material in the oil displacement system and the stability of the inorganic water plugging material in the oil displacement system by adding a suspending agent and a dispersing agent.

[0092] The present application has the following advantages:

[0093] Resource utilization and environmental protection: the use of waste agricultural and forestry biomass as one of the key components realizes high-value utilization of waste, reduces costs, and is environmentally friendly.

[0094] High performance: through fine compounding and synergistic effect of agricultural and forestry biomass and various inorganic materials, the obtained material has high compressive strength (up to 1.7 MPa or more), controllable curing time (24-48 h), and is suitable for high-temperature reservoir environments above 140℃.

[0095] Good stability: through the joint action of suspending agents and dispersing agents, the system has high stability and low water separation rate, ensuring the uniformity and pumpability of the slurry during construction.

[0096] Clear synergistic mechanism:

[0097] High-activity mineral admixture: adsorbed on the formation rock through van der Waals force under high temperature and high pressure, forming a dense packing structure, which resists erosion and locks water due to its high hardness and porous structure.

[0098] Suspension agent: the layered silicate structure swells when water is added, forming a gel-like barrier.

[0099] Dispersing agent: generates a chain or ring polymer by reacting with metal ions through functional groups, increasing the system strength and preventing component aggregation.

[0100] High-performance silicate: after hydrolysis, it reacts with metal ions to form insoluble precipitates, forming a three-dimensional network structure.

[0101] Retarder: Delay the precipitation reaction by coordination with metal ions through phenolic hydroxyl and carboxyl, control the curing time.

[0102] Agricultural and forestry biomass: The large number of hydroxyl groups contained therein enhance adhesion to formation rocks through hydrogen bonds and van der Waals forces; organic acids produced by degradation at high temperatures can react with calcium and magnesium ions to form precipitates, further enhancing strength.

[0103] Example embodiments have been disclosed herein and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that features, characteristics or elements described in connection with a particular embodiment can be used in conjunction with other embodiments unless otherwise explicitly stated. Accordingly, it will be understood that various changes in form and details can be made without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

1. An inorganic composite high-strength oil and water well plugging material, characterized in that, Made from the following raw materials by weight percentage: The ingredients include 15%–20% highly active mineral admixtures, 2%–8% high-performance silicates, 3%–5% agricultural and forestry biomass materials, 5%–8% suspending agents, 0.5%–0.7% dispersants, 0.04%–0.05% retarder, 1%–2% reinforcing agents, 1%–2% itaconic acid-modified acrylates, pH adjusters, and water.

2. The water-blocking material according to claim 1, characterized in that, The highly active mineral admixture has a specific surface area of ​​400–450 m² / kg and is composed of the following components by mass percentage: calcium oxide 40%–55%, silicon dioxide 30%–45%, aluminum oxide 10%–20%, magnesium oxide 10%–20%, manganese oxide 0.5%–1%, and ferrous oxide 0.5%–1%.

3. The water-blocking material according to claim 1, characterized in that, The agricultural and forestry biomass material is rice husk and / or straw powder that has been mechanically ground to a particle size of 1-10 μm; and / or, the reinforcing agent is composed of the following components by mass percentage: 30%-50% lime, 30%-40% calcium carbonate, and the balance being calcium chloride, and the particle size of the reinforcing agent is 3-10 μm.

4. The water-blocking material according to claim 1, characterized in that, The dispersant is composed of the following components by mass percentage: 30%–40% lignin sulfonate, 10%–30% sodium polyphosphate, and the balance being sodium dodecyl sulfonate; and / or, the retarder is composed of the following components by mass percentage: 20%–30% salicylic acid, 30%–40% tannic acid, and the balance being polymethyl methacrylate.

5. The water-blocking material according to claim 1, characterized in that, The suspending agent consists of the following components by mass percentage Composition: 40%–60% silicon dioxide, 20%–30% aluminum oxide, 10%–20% magnesium oxide, 1%–5% iron oxide, with the balance being fly ash; and / or, the pH adjuster is composed of the following components by mass percentage: 60%–75% sodium carbonate, 20%–35% sodium bicarbonate, with the balance being sodium hydroxide.

6. The water-blocking material according to claim 1, characterized in that, The reinforcing agent is composed of the following raw materials by mass fraction: 30%–50% lime, 30%–40% calcium carbonate, and the balance being calcium chloride.

7. The water-blocking material according to claim 1, characterized in that, The itaconic acid-modified acrylate is prepared by the following method: Itaconic acid was dissolved in deionized water, a reflux device was set up, and after stirring evenly, it was added to the polymerization reactor. Nitrogen gas was introduced for 10 minutes to remove air from the reaction system. Nitrogen gas was continuously introduced throughout the polymerization process so that the reaction was carried out under nitrogen protection. The temperature of the reaction solution was heated to the reflux temperature with stirring. Add the mixture of acrylate monomers and initiator dropwise, and continue the reaction for 1 hour to ensure the reaction is complete; After the reaction was completed, the reaction solution was cooled to room temperature, and after precipitation, filtration, washing and drying, itaconic acid modified acrylate was obtained.

8. A method for preparing the inorganic composite high-strength oil and water well plugging material as described in any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: S1. Add pH adjuster, suspending agent, retarder, agricultural and forestry biomass materials, and itaconic acid modified acrylate to water, stir, and obtain mixture a; S2. Add the dispersant and high-performance silicate to the mixture a obtained in step S1, stir, and obtain mixture b; S3. Mix the highly active mineral admixture and reinforcing agent evenly to obtain mixture c; S4. Add the mixture c obtained in step S3 to the mixture b obtained in step S2, and stir to obtain the water-blocking material.

9. The preparation method according to claim 8, characterized in that, In step S1, the stirring speed is 400–600 r / min and the stirring time is 10–20 min; in step S2, the stirring speed is 400–600 r / min and the stirring time is 10–20 min; in step S4, the stirring speed is 500–700 r / min and the stirring time is 10–20 min.

10. The preparation method according to claim 8, characterized in that, The agricultural and forestry biomass materials are prepared by the following method: After cleaning and drying the raw materials of rice husks, straw and agricultural and forestry waste, the biomass raw materials are crushed using a crusher, and then screened with a vibrating screen to obtain uniform particles of 30 mesh. The pre-selected 30-mesh uniform biomass particles were placed in a Raymond mill, and the rotation speed was controlled. The process was repeated multiple times until the diameter of the raw material reached the 1-10 μm level.

Images