Water shutoff agent for oil field and preparation method of water shutoff agent

Abstract

The invention relates to the technical field of water shutoff agents, in particular to a water shutoff agent for an oil field and a preparation method thereof, and the water shutoff agent comprises the following raw materials in parts by weight: 35-40 parts of anionic polyacrylamide, 5-8 parts of a cross-linking agent, 3-5 parts of an accelerant, 7-11 parts of a modified additive based on synergistic liquid, 2-3 parts of a silane coupling agent KH560, 4-7 parts of a supplementing agent and 25-30 parts of water. According to the water plugging agent for the oil field, raw materials such as anionic polyacrylamide, the cross-linking agent, the accelerant and the like are blended with the synergistic liquid-based modified additive and the supplementing agent, and the raw materials are directly co-compounded and co-synergized, so that the obtained product is excellent in water plugging rate performance and poor in oil plugging rate, and the balance coordination of the water plugging rate and the oil plugging rate of the water plugging agent is remarkable; the product has excellent selectivity, remarkable plugging strength effect, and excellent temperature change resistance and salt corrosion resistance stability effect.

Description

Technical Field

[0001] The invention relates to the technical field of water plugging agents, and in particular to a water plugging agent used in oil fields and a preparation method thereof. Background Art

[0002] When water injection is carried out on an oil field, a large number of large channels will be generated in the oil layer due to long-term scouring of the injected water; and due to fracturing transformation, the artificial fractures become more obvious water flow advantage channels, resulting in ineffective circulation of the injected water; the existing oil field water plugging agent adopts organic-inorganic composite as the water plugging material, but the inorganic-organic combination leads to poor interface of the raw materials, and it is difficult to coordinate and achieve the balance between the water plugging rate and the oil plugging rate of the product, and the product has poor sealing strength, which limits the use efficiency of the product. At the same time, the product has poor temperature change resistance and salt corrosion resistance stability, which further affects the use efficiency of the product. Based on this, the present invention further improves it. Summary of the invention

[0003] In view of the defects of the prior art, the object of the present invention is to provide a water plugging agent for oil fields and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0004] The present invention solves the technical problem by adopting the following technical solution:

[0005] The present invention provides a water plugging agent for oil fields, comprising the following raw materials in parts by weight:

[0006] 35-40 parts of anionic polyacrylamide, 5-8 parts of crosslinking agent, 3-5 parts of accelerator, 7-11 parts of modified additive based on synergistic liquid, 2-3 parts of silane coupling agent KH560, 4-7 parts of supplement and 25-30 parts of water.

[0007] Preferably, the water plugging agent for oil fields comprises the following raw materials in parts by weight:

[0008] 37.5 parts of anionic polyacrylamide, 6.5 parts of crosslinking agent, 4 parts of accelerator, 9 parts of modification additive based on synergistic liquid, 2.5 parts of silane coupling agent KH560, 5.5 parts of replenisher and 27.5 parts of water.

[0009] Preferably, the molecular weight of the anionic polyacrylamide is ≥15 million, and the degree of hydrolysis is ≥15; the crosslinking agent is a water-soluble phenolic resin; the accelerator is an imidazole accelerator, and the imidazole accelerator is 2-methylimidazole.

[0010] Preferably, the preparation method of the modified additive based on the synergistic liquid is:

[0011] S01: placing the nano-montmorillonite in a 5% dopamine hydrochloride solution with a mass fraction of 3 to 5 times the total amount of the nano-montmorillonite for ultrasonic treatment to obtain a nano-montmorillonite solution;

[0012] S02: 2-5 parts of cerium nitrate solution, 1-3 parts of urea solution and 2-4 parts of hydroxyapatite are mixed to obtain cerium nitrate solution;

[0013] 5-8 parts of nano-montmorillonite liquid and 3-5 parts of cerium nitrate liquid are mixed and ball-milled at a speed of 1500 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a nano-montmorillonite modifier.

[0014] S03: The nano-montmorillonite modifier and the synergistic liquid are continuously mixed and ball-milled at a weight ratio of 5:3, with a ball-milling speed of 750-850 r / min and stirring for 2 h. After the ball-milling is completed, the mixture is filtered and dried to obtain a modified additive based on the synergistic liquid.

[0015] Preferably, the ultrasonic power of the ultrasonic treatment is 350-400 W, and the ultrasonic treatment is performed for 20 min; the mass fraction of the urea solution is 2-5%; and the mass fraction of the cerium nitrate solution is 2-3%.

[0016] Preferably, the preparation method of the synergistic liquid is:

[0017] 2-5 parts of boron nitride, 1-3 parts of nano magnesium oxide and 4-7 parts of lanthanum solution are mixed evenly to obtain a compounding agent; carbon nanotubes, sodium stearate and the compounding agent are further mixed evenly in a weight ratio of 3:1:5 to obtain a synergistic solution.

[0018] Preferably, the lanthanum solution is a lanthanum chloride solution with a mass fraction of 5%; the particle size of the carbon nanotubes is 50-100 nm and the length is 5-10 μm.

[0019] Preferably, the preparation method of the tonic is:

[0020] S101: placing graphene in a sufficient amount of 5% by mass sulfuric acid solution and stirring the mixture evenly, then washing, filtering and drying the mixture, and preheating the dried graphene at 60-65° C. for 1 h to obtain preheated graphene;

[0021] S102: adding 2 to 4 parts of calcium carbonate, 1 to 3 parts of lignocellulose and 1 to 2 parts of sodium silicate solution to 5 to 8 parts of sodium lignin sulfonate solution and stirring evenly to obtain a treated solution;

[0022] The preheated graphene and the treatment liquid are stirred in a weight ratio of 2:5. After the stirring is completed, the mixture is filtered and dried to obtain a tonic agent.

[0023] Preferably, the mass fraction of the sodium silicate solution is 2-5%; the mass fraction of the sodium lignin sulfonate solution is 4-7%; the stirring speed of the stirring treatment is 550-750 r / min, and the stirring is for 1-2 hours.

[0024] The present invention also provides a method for preparing a water plugging agent for oil fields, comprising the following steps: weighing raw materials according to weight, and mixing the raw materials sufficiently to obtain the water plugging agent for oil fields.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The water plugging agent for oil fields of the present invention adopts anionic polyacrylamide, crosslinking agent, accelerator and other raw materials to adjust the modified additives and the compensating agent based on the synergistic liquid. The raw materials are coordinated and enhanced together. The obtained product has excellent water plugging rate performance and poor oil plugging rate. The water plugging rate and the oil plugging rate of the water plugging agent are significantly balanced and coordinated. The product has excellent selectivity and significant plugging strength effect. At the same time, the product has excellent temperature change resistance and salt corrosion resistance stability. The modified additive based on the synergistic liquid adopts nano-montmorillonite to be treated with a dopamine hydrochloride solution, and then mixed with a cerium nitrate liquid for ball milling treatment. The cerium nitrate solution, urea solution and hydroxyapatite in the cerium nitrate liquid are fully blended to obtain the cerium nitrate liquid. The synergistic effect of the nano-montmorillonite modifier and the synergistic liquid is optimized through the co-adjustment and coordination between the raw materials. At the same time, the nano-montmorillonite is used as a matrix and the cerium nitrate liquid is mixed with the cerium nitrate liquid. Improved coordination: Nano-montmorillonite has a barrier effect and plays a better role in plugging. At the same time, it is combined with hydroxyapatite in the cerium nitrate solution as a point adsorption to further enhance the water plugging rate. At the same time, the boron nitride, nano-magnesium oxide and lanthanum solution in the synergistic liquid are blended, and then further blended with carbon nanotubes, sodium stearate and a compounding agent, so that the synergistic liquid is coordinated with the nano-montmorillonite modifier to further enhance the coordination of system performance and improve the product's resistance to temperature changes and salt corrosion. At the same time, the compensator uses graphene to be treated with an acid solution, and then thermally improved to optimize its active efficiency, and is improved in combination with the treatment liquid. The treatment liquid uses calcium carbonate, cellulose and sodium silicate solution, and sodium lignin sulfonate solution to coordinate and synergize. Through the synergistic effect between the raw materials, the performance of the product is further enhanced, and the system's performance coordination and performance stability are optimized. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] A water plugging agent for oil fields in this embodiment includes the following raw materials in parts by weight:

[0029] 35-40 parts of anionic polyacrylamide, 5-8 parts of crosslinking agent, 3-5 parts of accelerator, 7-11 parts of modified additive based on synergistic liquid, 2-3 parts of silane coupling agent KH560, 4-7 parts of supplement and 25-30 parts of water.

[0030] A water plugging agent for oil fields in this embodiment includes the following raw materials in parts by weight:

[0031] 37.5 parts of anionic polyacrylamide, 6.5 parts of crosslinking agent, 4 parts of accelerator, 9 parts of modification additive based on synergistic liquid, 2.5 parts of silane coupling agent KH560, 5.5 parts of replenisher and 27.5 parts of water.

[0032] The molecular weight of the anionic polyacrylamide in this embodiment is ≥15 million, and the degree of hydrolysis is ≥15; the cross-linking agent is a water-soluble phenolic resin; the accelerator is an imidazole accelerator, and the imidazole accelerator is 2-methylimidazole.

[0033] The preparation method of the modified additive based on the synergistic liquid in this embodiment is:

[0034] S01: placing the nano-montmorillonite in a 5% dopamine hydrochloride solution with a mass fraction of 3 to 5 times the total amount of the nano-montmorillonite for ultrasonic treatment to obtain a nano-montmorillonite solution;

[0035] S02: 2-5 parts of cerium nitrate solution, 1-3 parts of urea solution and 2-4 parts of hydroxyapatite are mixed to obtain cerium nitrate solution;

[0036] 5-8 parts of nano-montmorillonite liquid and 3-5 parts of cerium nitrate liquid are mixed and ball-milled at a speed of 1500 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a nano-montmorillonite modifier.

[0037] S03: The nano-montmorillonite modifier and the synergistic liquid are continuously mixed and ball-milled at a weight ratio of 5:3, with a ball-milling speed of 750-850 r / min and stirring for 2 h. After the ball-milling is completed, the mixture is filtered and dried to obtain a modified additive based on the synergistic liquid.

[0038] The ultrasonic power of the ultrasonic treatment in this embodiment is 350-400W, and the ultrasonic treatment is performed for 20 minutes; the mass fraction of the urea solution is 2-5%; and the mass fraction of the cerium nitrate solution is 2-3%.

[0039] The preparation method of the synergistic liquid of this embodiment is:

[0040] 2-5 parts of boron nitride, 1-3 parts of nano magnesium oxide and 4-7 parts of lanthanum solution are mixed evenly to obtain a compounding agent; carbon nanotubes, sodium stearate and the compounding agent are further mixed evenly in a weight ratio of 3:1:5 to obtain a synergistic solution.

[0041] The lanthanum solution of this embodiment is a lanthanum chloride solution with a mass fraction of 5%; the particle size of the carbon nanotubes is 50-100 nm and the length is 5-10 μm.

[0042] The preparation method of the tonic agent of this embodiment is:

[0043] S101: placing graphene in a sufficient amount of 5% by mass sulfuric acid solution and stirring the mixture evenly, then washing, filtering and drying the mixture, and preheating the dried graphene at 60-65° C. for 1 h to obtain preheated graphene;

[0044] S102: adding 2 to 4 parts of calcium carbonate, 1 to 3 parts of lignocellulose and 1 to 2 parts of sodium silicate solution to 5 to 8 parts of sodium lignin sulfonate solution and stirring evenly to obtain a treated solution;

[0045] The preheated graphene and the treatment liquid are stirred in a weight ratio of 2:5. After the stirring is completed, the mixture is filtered and dried to obtain a tonic agent.

[0046] The mass fraction of the sodium silicate solution in this embodiment is 2-5%; the mass fraction of the sodium lignin sulfonate solution is 4-7%; the stirring speed of the stirring treatment is 550-750 r / min, and the stirring is performed for 1-2 hours.

[0047] The preparation method of a water plugging agent for oil fields in this embodiment includes the following steps: weighing raw materials according to weight parts, and mixing the raw materials thoroughly to obtain the water plugging agent for oil fields.

[0048] Example 1: A water plugging agent for oil fields in this example comprises the following raw materials in parts by weight:

[0049] 35 parts of anionic polyacrylamide, 5 parts of crosslinking agent, 3 parts of accelerator, 7 parts of modified additive based on synergistic liquid, 2 parts of silane coupling agent KH560, 4 parts of supplement and 25 parts of water.

[0050] The molecular weight of the anionic polyacrylamide in this embodiment is ≥15 million, and the degree of hydrolysis is ≥15; the cross-linking agent is a water-soluble phenolic resin; the accelerator is an imidazole accelerator, and the imidazole accelerator is 2-methylimidazole.

[0051] The preparation method of the modified additive based on the synergistic liquid in this embodiment is:

[0052] S01: placing the nano-montmorillonite in a 5% dopamine hydrochloride solution with a mass fraction of 3 times the total amount of the nano-montmorillonite for ultrasonic treatment to obtain a nano-montmorillonite solution;

[0053] S02: 2 parts of cerium nitrate solution, 1 part of urea solution and 2 parts of hydroxyapatite are mixed to obtain cerium nitrate solution;

[0054] 5 parts of nano-montmorillonite liquid and 3 parts of cerium nitrate liquid were mixed and ball-milled at a speed of 1500 r / min for 1 h. After the ball-milling was completed, the mixture was filtered and dried to obtain a nano-montmorillonite modifier.

[0055] S03: The nano-montmorillonite modifier and the synergistic liquid are mixed and ball-milled at a weight ratio of 5:3, with a ball-milling speed of 750 r / min and stirring for 2 h. After the ball-milling is completed, the mixture is filtered and dried to obtain a modified additive based on the synergistic liquid.

[0056] The ultrasonic power of the ultrasonic treatment in this embodiment is 350W, and the ultrasonic treatment is performed for 20 minutes; the mass fraction of the urea solution is 2%; and the mass fraction of the cerium nitrate solution is 2%.

[0057] The preparation method of the synergistic liquid of this embodiment is:

[0058] 2 parts of boron nitride, 1 part of nano magnesium oxide and 4 parts of lanthanum solution are mixed evenly to obtain a compounding agent; carbon nanotubes, sodium stearate and the compounding agent are further mixed evenly in a weight ratio of 3:1:5 to obtain a synergistic solution.

[0059] The lanthanum solution of this embodiment is a lanthanum chloride solution with a mass fraction of 5%; the particle size of the carbon nanotubes is 50nm and the length is 5μm.

[0060] The preparation method of the tonic agent of this embodiment is:

[0061] S101: placing graphene in a sufficient amount of 5% by mass sulfuric acid solution and stirring the mixture evenly, then washing, filtering and drying the mixture, and preheating the dried graphene at 60° C. for 1 h to obtain preheated graphene;

[0062] S102: adding 2 parts of calcium carbonate, 1 part of lignocellulose and 1 part of sodium silicate solution to 5 parts of sodium lignin sulfonate solution and stirring evenly to obtain a treated solution;

[0063] The preheated graphene and the treatment liquid are stirred in a weight ratio of 2:5. After the stirring is completed, the mixture is filtered and dried to obtain a tonic agent.

[0064] The mass fraction of the sodium silicate solution in this embodiment is 2%; the mass fraction of the sodium lignin sulfonate solution is 4%; the stirring speed of the stirring process is 550 r / min, and the stirring is for 1 hour.

[0065] The preparation method of a water plugging agent for oil fields in this embodiment includes the following steps: weighing raw materials according to weight parts, and mixing the raw materials thoroughly to obtain the water plugging agent for oil fields.

[0066] Example 2: A water plugging agent for oil fields according to this example comprises the following raw materials in parts by weight:

[0067] 40 parts of anionic polyacrylamide, 8 parts of crosslinking agent, 5 parts of accelerator, 11 parts of modification additive based on synergistic liquid, 3 parts of silane coupling agent KH560, 7 parts of supplement and 30 parts of water.

[0068] The molecular weight of the anionic polyacrylamide in this embodiment is ≥15 million, and the degree of hydrolysis is ≥15; the crosslinking agent is a water-soluble phenolic resin; the accelerator is an imidazole accelerator, and the imidazole accelerator is 2-methylimidazole.

[0069] The preparation method of the modified additive based on the synergistic liquid in this embodiment is:

[0070] S01: placing the nano-montmorillonite in a 5% dopamine hydrochloride solution with a mass fraction of 5 times the total amount of the nano-montmorillonite for ultrasonic treatment to obtain a nano-montmorillonite solution;

[0071] S02: 5 parts of cerium nitrate solution, 3 parts of urea solution and 4 parts of hydroxyapatite are mixed to obtain cerium nitrate solution;

[0072] 8 parts of nano-montmorillonite liquid and 5 parts of cerium nitrate liquid were mixed and ball-milled at a speed of 1500 r / min for 1 h. After the ball-milling was completed, the mixture was filtered and dried to obtain a nano-montmorillonite modifier.

[0073] S03: The nano-montmorillonite modifier and the synergistic liquid are continuously mixed and ball-milled at a weight ratio of 5:3, with a ball-milling speed of 850 r / min and stirring for 2 h. After the ball-milling is completed, the mixture is filtered and dried to obtain a modified additive based on the synergistic liquid.

[0074] The ultrasonic power of the ultrasonic treatment in this embodiment is 400W, and the ultrasonic treatment is performed for 20 minutes; the mass fraction of the urea solution is 5%; and the mass fraction of the cerium nitrate solution is 3%.

[0075] The preparation method of the synergistic liquid of this embodiment is:

[0076] 5 parts of boron nitride, 3 parts of nano magnesium oxide and 7 parts of lanthanum solution are mixed evenly to obtain a compounding agent; carbon nanotubes, sodium stearate and the compounding agent are further mixed evenly in a weight ratio of 3:1:5 to obtain a synergistic solution.

[0077] The lanthanum solution of this embodiment is a lanthanum chloride solution with a mass fraction of 5%; the particle size of the carbon nanotubes is 100nm and the length is 10μm.

[0078] The preparation method of the tonic agent of this embodiment is:

[0079] S101: placing graphene in a sufficient amount of 5% by mass sulfuric acid solution and stirring the mixture evenly, then washing, filtering and drying the mixture, and preheating the dried graphene at 65° C. for 1 h to obtain preheated graphene;

[0080] S102: adding 4 parts of calcium carbonate, 3 parts of lignocellulose and 2 parts of sodium silicate solution to 8 parts of sodium lignin sulfonate solution and stirring evenly to obtain a treated solution;

[0081] The preheated graphene and the treatment liquid are stirred in a weight ratio of 2:5. After the stirring is completed, the mixture is filtered and dried to obtain a tonic agent.

[0082] The mass fraction of the sodium silicate solution in this embodiment is 5%; the mass fraction of the sodium lignin sulfonate solution is 47%; the stirring speed of the stirring process is 750 r / min, and the stirring is for 2 hours.

[0083] The preparation method of a water plugging agent for oil fields in this embodiment includes the following steps: weighing raw materials according to weight parts, and mixing the raw materials thoroughly to obtain the water plugging agent for oil fields.

[0084] Embodiment 3, a water plugging agent for oil fields of this embodiment comprises the following raw materials in parts by weight:

[0085] 37.5 parts of anionic polyacrylamide, 6.5 parts of crosslinking agent, 4 parts of accelerator, 9 parts of modification additive based on synergistic liquid, 2.5 parts of silane coupling agent KH560, 5.5 parts of replenisher and 27.5 parts of water.

[0086] The molecular weight of the anionic polyacrylamide in this embodiment is ≥15 million, and the degree of hydrolysis is ≥15; the crosslinking agent is a water-soluble phenolic resin; the accelerator is an imidazole accelerator, and the imidazole accelerator is 2-methylimidazole.

[0087] The preparation method of the modified additive based on the synergistic liquid in this embodiment is:

[0088] S01: placing the nano-montmorillonite in a 5% dopamine hydrochloride solution with a mass fraction of 4 times the total amount of the nano-montmorillonite for ultrasonic treatment to obtain a nano-montmorillonite solution;

[0089] S02: 3.5 parts of cerium nitrate solution, 2 parts of urea solution and 3 parts of hydroxyapatite are mixed to obtain cerium nitrate solution;

[0090] 6.5 parts of nano-montmorillonite liquid and 4 parts of cerium nitrate liquid were mixed and ball-milled at a speed of 1500 r / min for 1 h. After the ball-milling was completed, the mixture was filtered and dried to obtain a nano-montmorillonite modifier.

[0091] S03: The nano-montmorillonite modifier and the synergistic liquid are mixed and ball-milled at a weight ratio of 5:3, with a ball-milling speed of 800 r / min and stirring for 2 h. After the ball-milling is completed, the mixture is filtered and dried to obtain a modified additive based on the synergistic liquid.

[0092] The ultrasonic power of the ultrasonic treatment in this embodiment is 375W, and the ultrasonic treatment lasts for 20 minutes; the mass fraction of the urea solution is 3.5%; and the mass fraction of the cerium nitrate solution is 2.5%.

[0093] The preparation method of the synergistic liquid of this embodiment is:

[0094] 3.5 parts of boron nitride, 2 parts of nano magnesium oxide and 5.5 parts of lanthanum solution are mixed evenly to obtain a compounding agent; carbon nanotubes, sodium stearate and the compounding agent are further mixed evenly in a weight ratio of 3:1:5 to obtain a synergistic solution.

[0095] The lanthanum solution of this embodiment is a lanthanum chloride solution with a mass fraction of 5%; the particle size of the carbon nanotubes is 75nm and the length is 7.5μm.

[0096] The preparation method of the tonic agent of this embodiment is:

[0097] S101: placing graphene in a sufficient amount of 5% by mass sulfuric acid solution and stirring the mixture evenly, then washing, filtering and drying the mixture, and preheating the dried graphene at 62.5° C. for 1 h to obtain preheated graphene;

[0098] S102: adding 3 parts of calcium carbonate, 2 parts of lignocellulose and 1.5 parts of sodium silicate solution to 5-8 parts of sodium lignin sulfonate solution and stirring evenly to obtain a treated solution;

[0099] The preheated graphene and the treatment liquid are stirred in a weight ratio of 2:5. After the stirring is completed, the mixture is filtered and dried to obtain a tonic agent.

[0100] The mass fraction of the sodium silicate solution in this embodiment is 3.5%; the mass fraction of the sodium lignin sulfonate solution is 5.5%; the stirring speed of the stirring treatment is 600 r / min, and the stirring is performed for 1.5 hours.

[0101] The preparation method of a water plugging agent for oil fields in this embodiment includes the following steps: weighing raw materials according to weight parts, and mixing the raw materials thoroughly to obtain the water plugging agent for oil fields.

[0102] Comparative Example 1 is different from Example 3 in that no modifying additive based on synergistic liquid is added.

[0103] Comparative Example 2 is different from Example 3 in that no nano-montmorillonite modifier is added in the preparation of the modified additive based on the synergistic liquid.

[0104] Comparative Example 3 is different from Example 3 in that no cerium nitrate solution is added in the preparation of the nano-montmorillonite modifier.

[0105] Comparative Example 4 is different from Example 3 in that no urea solution and no hydroxyapatite are added to the cerium nitrate solution.

[0106] Comparative Example 5 is different from Example 3 in that no synergistic liquid is added in the preparation of the modified additive based on the synergistic liquid.

[0107] Comparative Example 6 is different from Example 3 in that no carbon nanotubes or sodium stearate are added to the synergistic liquid.

[0108] Comparative Example 7 is different from Example 3 in that no compounding agent is added to the synergistic liquid.

[0109] Comparative Example 8 is different from Example 3 in that boron nitride and nano magnesium oxide are not added to the compounding agent.

[0110] Comparative Example 9 is different from Example 3 in that the lanthanum solution in the compounding agent is replaced by water.

[0111] Comparative Example 10 is different from Example 3 in that no supplementing agent is added.

[0112] Comparative Example 11 is different from Example 3 in that no treatment liquid is added to the replenisher.

[0113] Comparative Example 12 is different from Example 3 in that no calcium carbonate or lignocellulose is added to the treatment liquid.

[0114] The products of Examples 1 to 3 and Comparative Examples 1 to 12 were subjected to conventional performance tests for water blocking rate, oil blocking rate and product plugging strength. The performance test results are shown in Table 1 below. Table 1 is a performance test table of water blocking rate, oil blocking rate and plugging strength under conventional conditions.

[0115]

[0116] It can be concluded from Examples 1 to 3 and Comparative Examples 1 to 12 that Example 3 of the present invention has a significant water blocking rate effect, a poor oil blocking rate effect and excellent blocking strength, the product has excellent selectivity, and the product has a significant blocking strength effect, and the performance of the products of Comparative Examples 1 to 12 is not as good as the performance of the product of Example 3.

[0117] The product was placed in 5% sodium chloride salt spray for 24 hours, then placed at 60°C for 6 hours, then placed at 110°C for 12 hours, and finally placed at 5°C for 6 hours to test the product's temperature change resistance and salt corrosion resistance stability. The performance test results are shown in Table 2 below. Table 2 is a table showing the performance impact of the product under temperature change resistance and salt corrosion resistance conditions;

[0118]

[0119] From the above performance tests, it can be seen that the product of Example 3 also has excellent temperature change resistance and salt corrosion resistance stability. The product does not add a modified additive based on a synergistic liquid and does not add one of the supplementing agents. The product performance deteriorates significantly. Only when the two are used in combination and work together, the performance effect of the product is most significant.

[0120] From Example 3 and Comparative Examples 2 to 5, it can be concluded that when the nano-montmorillonite modifier is not added in the preparation of the modified additive based on the synergistic liquid, the cerium nitrate solution is not added in the preparation of the nano-montmorillonite modifier, the synergistic liquid is not added in the preparation of the modified additive based on the synergistic liquid, and the urea solution and hydroxyapatite are not added to the cerium nitrate solution, the performance of the product has a significant trend of deterioration. The nano-montmorillonite modifier obtained by the specific method of the present invention has the most significant performance effect.

[0121] From Example 3 and Comparative Examples 6 to 9, it can be concluded that the performance of the products all tended to deteriorate to varying degrees when no carbon nanotubes, sodium stearate, or compounding agent was added to the synergistic liquid, no boron nitride or nano magnesium oxide was added to the compounding agent, and the lanthanum solution in the compounding agent was replaced by water.

[0122] The modified additive based on the synergistic liquid prepared by the synergistic liquid obtained by the specific method of the present invention and the nano-montmorillonite modifier of the present invention has the most significant performance effect of the product, and other methods are not as obvious as the effect of the present invention, and the preparation of the synergistic liquid of the present invention is proprietary, and only by using the synergistic liquid of the present invention, the performance effect of the product is the most significant;

[0123] It can be concluded from Example 3 and Comparative Examples 11-12 that when no treatment liquid is added to the replenisher and calcium carbonate and lignocellulose are not added to the treatment liquid, the performance of the product tends to deteriorate. The replenisher obtained by the specific method of the present invention has the most significant performance effect of the product.

[0124] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0125] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A water plugging agent for oil fields, characterized in that: It includes the following raw materials in parts by weight: 35-40 parts of anionic polyacrylamide, 5-8 parts of crosslinking agent, 3-5 parts of accelerator, 7-11 parts of modified additive based on synergistic liquid, 2-3 parts of silane coupling agent KH560, 4-7 parts of supplement and 25-30 parts of water.

2. A water plugging agent for oil fields according to claim 1, characterized in that: The water plugging agent for oil fields comprises the following raw materials in parts by weight: 37.5 parts of anionic polyacrylamide, 6.5 parts of crosslinking agent, 4 parts of accelerator, 9 parts of modification additive based on synergistic liquid, 2.5 parts of silane coupling agent KH560, 5.5 parts of replenisher and 27.5 parts of water.

3. The water plugging agent for oil fields according to claim 1, characterized in that: The molecular weight of the anionic polyacrylamide is ≥15 million, and the degree of hydrolysis is ≥15; the crosslinking agent is a water-soluble phenolic resin; the accelerator is an imidazole accelerator, and the imidazole accelerator is 2-methylimidazole.

4. The water plugging agent for oil fields according to claim 1, characterized in that: The preparation method of the modified additive based on the synergistic liquid is: S01: placing the nano-montmorillonite in a 5% dopamine hydrochloride solution with a mass fraction of 3 to 5 times the total amount of the nano-montmorillonite for ultrasonic treatment to obtain a nano-montmorillonite solution; S02: 2-5 parts of cerium nitrate solution, 1-3 parts of urea solution and 2-4 parts of hydroxyapatite are mixed to obtain cerium nitrate solution; 5-8 parts of nano-montmorillonite liquid and 3-5 parts of cerium nitrate liquid are mixed and ball-milled at a speed of 1500 r / min for 1 hour. After the ball-milling is completed, the mixture is filtered and dried to obtain a nano-montmorillonite modifier. S03: The nano-montmorillonite modifier and the synergistic liquid are continuously mixed and ball-milled at a weight ratio of 5:3, with a ball-milling speed of 750-850 r / min and stirring for 2 h. After the ball-milling is completed, the mixture is filtered and dried to obtain a modified additive based on the synergistic liquid.

5. The water plugging agent for oil fields according to claim 4, characterized in that: The ultrasonic power of the ultrasonic treatment is 350-400W, and the ultrasonic treatment lasts for 20 minutes; the mass fraction of the urea solution is 2-5%; and the mass fraction of the cerium nitrate solution is 2-3%.

6. The water plugging agent for oil fields according to claim 4, characterized in that: The preparation method of the synergistic liquid is: 2-5 parts of boron nitride, 1-3 parts of nano magnesium oxide and 4-7 parts of lanthanum solution are uniformly mixed to obtain a compounding agent; The carbon nanotubes, sodium stearate and the compounding agent are further mixed in a weight ratio of 3:1:5 to obtain a synergistic solution.

7. The water plugging agent for oil fields according to claim 6, characterized in that: The lanthanum solution is a lanthanum chloride solution with a mass fraction of 5%; the particle size of the carbon nanotubes is 50-100 nm and the length is 5-10 μm.

8. The water plugging agent for oil fields according to claim 1, characterized in that: The preparation method of the tonic is: S101: placing graphene in a sufficient amount of 5% by mass sulfuric acid solution and stirring the mixture evenly, then washing, filtering and drying the mixture, and preheating the dried graphene at 60-65° C. for 1 h to obtain preheated graphene; S102: adding 2 to 4 parts of calcium carbonate, 1 to 3 parts of lignocellulose and 1 to 2 parts of sodium silicate solution to 5 to 8 parts of sodium lignin sulfonate solution and stirring evenly to obtain a treated solution; The preheated graphene and the treatment liquid are stirred in a weight ratio of 2:

5. After the stirring is completed, the mixture is filtered and dried to obtain a tonic agent.

9. The water plugging agent for oil fields according to claim 8, characterized in that: The mass fraction of the sodium silicate solution is 2-5%; the mass fraction of the sodium lignin sulfonate solution is 4-7%; the stirring speed of the stirring treatment is 550-750 r / min, and the stirring is performed for 1-2 hours.

10. The method for preparing the water plugging agent for oil field according to any one of claims 1 to 9, characterized in that: The following steps are involved: The raw materials are weighed according to weight and mixed thoroughly to obtain the water plugging agent for oil fields.

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