A hydrophobic flocculant, its preparation method and application

Abstract

The present invention relates to a hydrophobic flocculant, a preparation method and an application thereof in the field of oil and gas field chemical additives. The hydrophobic flocculant comprises a mixture of inorganic powder and organic powder; the weight of the inorganic powder is 25-50% of the weight of the organic powder; the average particle size of both the inorganic powder and the organic powder is 100-500 mesh; the hydrophobic flocculant disclosed by the present invention has excellent performance. The cement slurry prepared with it as the key treatment agent has excellent anti-water dispersion characteristics, the initial consistency is lower than 30Bc, meeting the on-site pumping requirements. The thickening time of the cement slurry at 80-160 °C can be adjusted within 3-6h, without obvious retardation effect, and has no adverse effect on the thickening time and the strength of the cement stone, meeting the technical requirements for plugging deep water layers in oil drilling.

Description

Technical Field

[0001] The present invention relates to the field of chemical additives for oil and gas fields. More specifically, it relates to a hydrophobic flocculant, its preparation method and application. Background Art

[0002] According to statistics, the incidence rate of lost circulation in the world accounts for about 20% - 25% of the total number of wells. In the global oil industry, billions of dollars are wasted every year due to lost circulation. Lost circulation not only wastes a large amount of drilling time, loses a large amount of materials and drilling fluids, but may also cause a series of complex accidents such as blowout, well collapse, and stuck pipe, and even may lead to the abandonment of the entire wellbore, resulting in significant economic losses. Among them, the malignant lost circulation caused by lost circulation in water-bearing leakage layers and underground river leakage in groundwater layers has always been a world-class problem.

[0003] Water-bearing leakage layers are usually connected to underground undercurrents or underground rivers, and groundwater is very active. The lost circulation that occurs has a fast leakage rate and a large leakage volume, and is often very difficult to handle. Because the plugging slurry is generally a water-based system and has a good affinity with water, when the plugging slurry enters the formation, it will inevitably mix with water. The plugging slurry is easily diluted or transported along with the water flow. The direct results are: (1) Dilution reduces the viscosity of the plugging slurry and the concentration of the plugging material, and under the action of pressure, it is easy to flow away and is difficult to stay and accumulate near the entrance of the leakage layer; (2) For consolidated plugging slurries, it is difficult for the plugging liquid to coagulate and solidify after being diluted, or the coagulation strength is greatly reduced, making it difficult to support the destructive effect of the mud, resulting in plugging failure. (3) If there is flowing water in the formation water, under the action of the water flow, the plugging slurry will be quickly carried away by the formation water, and a plugging wall cannot be formed, leading to plugging failure. Plugging in water-bearing formations, especially formations with flowing water, has not been well solved.

[0004] Southwest Petroleum University has used intelligent gels in combination with cement slurries and achieved certain successful cases. Its main feature is to use the high viscosity and the property of not being easily diluted by water of the ZND series of intelligent gels to isolate the cement slurry from the formation water, without affecting the normal thickening and consolidation of the cement slurry. However, due to the complex and changeable characteristics of the formation fracture channels and formation water, when the ZND gel cannot completely block the contact between the formation water and the cement slurry, plugging is extremely likely to fail.

[0005] In the underwater operation site of the construction concrete industry, underwater non-dispersible cement or underwater non-dispersible concrete is often used for construction. It can be directly poured in water, is not prone to dispersion and segregation, and ensures the quality and strength of the poured concrete. Its core is to add a water-soluble polymer compound, generally called a flocculant, to ordinary concrete. By using the mutual attraction and cross-linking of its long-chain polymers, a network structure with strong adsorption capacity is formed to adsorb cement particles together. Even when flushed with water, it can well maintain the cohesive state, thus having the underwater non-dispersible effect. Due to the significant reduction in the efficiency of conventional water non-dispersants at high temperatures, the underwater non-dispersible concrete technology in the concrete industry has not yet been applied to the plugging operations in oil wells.

[0006] The flocculant is the core component of underwater non-dispersible concrete and is also a research hotspot of underwater non-dispersible concrete. In 1983, the Research Institute of Petroleum Science and Technology of China and Xibo Company carried out cooperation. After four years of research, the acrylate-based UWB-I type underwater non-dispersible concrete flocculant was developed in 1987, making China the third country to successfully develop the underwater non-dispersible concrete technology after Germany and Japan. In 2003, based on the UWB-1 and SCR type flocculants, the Research Institute of Petroleum Engineering Technology of China combined advanced technologies at home and abroad to develop the UWB-II type flocculant. This flocculant takes water-soluble sugar-based polymer as the main component and concrete fluidizing agent and setting regulator as auxiliary components. The new flocculant basically solves the problems such as poor compatibility and abnormal increase in water demand of the UWB-I type flocculant.

[0007] There are mainly three types of underwater non-dispersible concrete flocculants: cellulose-based, polyacrylamide-based, and polysaccharide-based. Common celluloses include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; common polysaccharides include chitosan, welan gum, and xanthan gum. In the initial stage of the application of underwater non-dispersible concrete, cellulose-based and polyacrylamide-based flocculants were mostly used. Because polyacrylamide is relatively inexpensive, it is more widely used. However, when using polyacrylamide to mix concrete, the viscosity is relatively large, the power requirement for mixing equipment is relatively high, it often sticks to the mixer and tank truck and is difficult to clean, and the mixing time is relatively long, the slump loss is fast, and the cohesiveness decreases significantly during underwater pouring, resulting in a relatively low strength on land and water, making it difficult to ensure the construction quality. The UWB-II type flocculant completely solves the defects of polyacrylamide-based flocculants and has become the most used flocculant in current construction. However, most flocculants are designed for cement concrete at normal or low temperatures. For the wellbore water layer conditions often encountered in oil industry drilling plugging, the formation is a medium-high temperature formation, the formation water salinity is higher, and some are saturated brines, which pose higher requirements for cement-based plugging materials. Summary of the Invention

[0008] To solve the above problems existing in the prior art, the present invention provides a hydrophobic flocculant with excellent anti-water dispersion characteristics. Specifically, it relates to a hydrophobic flocculant, its preparation method and application, to solve the problem that the current anti-dispersion flocculant cannot meet the technical requirements of oil well cement for plugging water layers, and to overcome the problems of insufficient anti-water dispersion at high temperatures, poor fluidity, extended thickening time, and strength loss of the consolidated body due to the water dispersion and dilution of the slurry in the existing treatment agent preparation.

[0009] One object of the present invention is to provide a hydrophobic flocculant, which comprises a mixture of inorganic powder and organic powder;

[0010] The weight of the inorganic powder can be 25-50% of the weight of the organic powder, preferably 30-40%;

[0011] Preferably, the average particle sizes of the inorganic powder and the organic powder are both 100-500 mesh, preferably 200-400 mesh; more preferably 200-300 mesh;

[0012] Preferably, the inorganic powder can be selected from at least one of calcium carbonate, fly ash, bentonite or silica, more preferably at least one of calcium carbonate and silica;

[0013] The organic powder is from an organic polymer; the organic polymer is obtained by monomer polymerization reaction of components including N-vinyl amide monomers, acrylamide monomers, vinyl-containing sulfonic acid monomers, acrylic acid monomers, and methacrylate monomers in a high molecular polymer solution; specifically, the organic polymer can be polymerized from the following components by weight percentage:

[0014] N-vinyl amide monomers 5-40%, preferably 7-30%;

[0015] Acrylamide monomers 4-30%, preferably 4-20%;

[0016] Vinyl-containing sulfonic acid monomers 40-85%, preferably 50-70%;

[0017] Acrylic acid monomers 2-20%, preferably 2-10%;

[0018] Methacrylate monomers 1-30%, preferably 10-25%.

[0019] Among them,

[0020] The N-vinyl amide monomers can be specifically selected from at least one of N-vinyl formamide, N-vinyl acetamide or N-methyl-N-vinyl acetamide. The N-vinyl amide monomers can be used to improve the temperature and salt resistance of the polymerization reactants.

[0021] The acrylamide monomer may be selected from at least one of acrylamide, N,N-dimethylacrylamide or N,N-diethylacrylamide.

[0022] The vinyl-containing sulfonic acid monomer may be selected from at least one of 2-acrylamido-2-methylpropane sulfonic acid or 2-acryloyloxy-2-methylpropane sulfonic acid. The vinyl-containing sulfonic acid monomer can be used to increase the temperature and salt resistance.

[0023] The acrylic acid monomer may be selected from at least one of acrylic acid and methacrylic acid. The acrylic acid monomer can be used to increase the water solubility.

[0024] The methacrylate monomer may be selected from at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate or butyl methacrylate. The methacrylate monomer can be used to increase the molecular weight of micellar polymerization.

[0025] The hydrophobic flocculant can make the prepared cement slurry have excellent anti-water dispersion effect. The cement slurry prepared with it as the key treatment agent can still maintain good underwater non-dispersing performance under high temperature conditions, can be non-segregating and non-dispersing in 80°C water, and has significantly stronger anti-water erosion ability than ordinary cement slurry systems, and has no obvious influence on the thickening time, early strength of cement, etc., and can greatly improve the success rate of plugging water layers underground.

[0026] The second object of the present invention is to provide a preparation method of the hydrophobic flocculant, which may include the following steps:

[0027] The hydrophobic flocculant is obtained by ball milling the components including the organic polymer and inorganic substances; preferably, before ball milling, the organic polymer can be dried and pulverized to obtain organic matter particles, and then the organic matter particles and inorganic substances are ball milled to obtain the hydrophobic flocculant. Among them, the drying temperature may be 70°C to 120°C, preferably 80°C to 100°C.

[0028] The organic polymer can be prepared by a method including the following steps:

[0029] The components including the N-vinylamide monomer, acrylamide monomer, vinyl-containing sulfonic acid monomer, acrylic acid monomer, methacrylate monomer are subjected to radical polymerization in a polymer material solution to obtain it.

[0030] Specifically, the preparation method of the organic polymer may include the following steps:

[0031] (1) Add components including the N-vinyl amide monomer, acrylamide monomer, vinyl-containing sulfonic acid monomer, acrylic acid monomer, and methacrylate monomer to a certain amount of deionized water, and adjust the pH value of the solution under stirring to obtain a mixed solution A;

[0032] (2) Add a polymer material to the mixed solution A, and pass nitrogen to obtain a mixed solution B;

[0033] (3) Add an initiator and a complexing agent to the mixed solution B and carry out a reaction to obtain a gel-like product. Among them,

[0034] In the step (1),

[0035] The monomers specifically may include the following components by weight percentage:

[0036] N-vinyl amide monomer 5-40%, preferably 7-30%;

[0037] Acrylamide monomer 4-30%, preferably 4-20%;

[0038] Vinyl-containing sulfonic acid monomer 40-85%, preferably 50-70%;

[0039] Acrylic acid monomer 2-20%, preferably 2-10%;

[0040] Methacrylate monomer 1-30%, preferably 10-25%.

[0041] Among them,

[0042] The N-vinyl amide monomer specifically may be selected from at least one of N-vinyl formamide, N-vinyl acetamide, or N-methyl-N-vinyl acetamide. The N-vinyl amide monomer can be used to improve the temperature and salt resistance of the polymerization reactant.

[0043] The acrylamide monomer may be selected from at least one of acrylamide, N,N-dimethylacrylamide, or N,N-diethylacrylamide.

[0044] The vinyl-containing sulfonic acid monomer may be selected from at least one of 2-acrylamido-2-methylpropane sulfonic acid or 2-acryloyloxy-2-methylpropane sulfonic acid. The vinyl-containing sulfonic acid monomer can be used to increase the temperature and salt resistance.

[0045] The acrylic acid monomer may be selected from at least one of acrylic acid and methacrylic acid. The acrylic acid monomer can be used to increase water solubility.

[0046] The methacrylate monomer can be selected from at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate or butyl methacrylate. The methacrylate monomer can be used to increase the molecular weight of micelle polymerization.

[0047] The pH value of the adjusting solution is adjusted to 6-10, preferably 7-9; specifically, it can be adjusted with an alkaline substance; the alkaline substance can be at least one of sodium hydroxide, potassium hydroxide or ammonia water.

[0048] The total weight concentration of the monomers in the mixed solution A can be 10-50%, preferably 20-50%, more preferably 25-45%.

[0049] In the step (2),

[0050] The polymer material is dissolved in an aqueous solution containing monomers, and the monomers are polymerized gently in the polymer solution, which is easy to control;

[0051] The polymer material is a water-soluble polymer, preferably at least one of xanthan gum, polyanionic cellulose, cyclodextrin or starch; and / or,

[0052] The weight of the polymer material can be 0.05-3% of the weight of the mixed solution A, preferably 0.1-2%;

[0053] The specific time for passing nitrogen can be 0.5-2 hours, preferably 0.5 hours-1 hour.

[0054] In the step (3),

[0055] The mixed solution B reacts under the conditions of a temperature of 30°C-80°C, adding an initiator and a complexing agent, and the reaction time is 1-8 hours to obtain a gel-like product;

[0056] The initiator can be an oxidation-reduction initiator; among them, the oxidant is at least one of hydrogen peroxide, ammonium persulfate, potassium persulfate, and the reducing agent is at least one of sodium bisulfite or tetramethylethylenediamine. The oxidation-reduction initiator can be any combination of any one of the oxidants and any one of the reducing agents. The amount of the initiator can be adjusted according to specific needs.

[0057] The amount of the oxidant can be 0.1%-0.8% of the total weight of all monomers, preferably 0.1%-0.7%, more preferably 0.3%-0.7%;

[0058] The molar ratio of the amount of the reducing agent to the amount of the oxidant can be between (0.8-1):1.

[0059] In the step (3),

[0060] The dosage of the complexing agent can be 0.03-0.2% by weight of the mixed solution B, preferably 0.05-0.1%; and / or,

[0061] The complexing agent can be an organic amine complexing agent, preferably disodium ethylenediaminetetraacetate.

[0062] In step (3),

[0063] The reaction temperature of the reaction can be 30°C to 80°C, preferably 40°C to 70°C;

[0064] The reaction time of the reaction can be 1 to 8 hours, preferably 2 to 6 hours.

[0065] In specific implementation,

[0066] The gel-like product obtained in step (3) can be cut, dried, and crushed to obtain organic matter particles, and then the organic matter particles and inorganic matter are finely ground at high speed in a ball mill to obtain the hydrophobic flocculant;

[0067] The drying temperature can be 70°C to 120°C, preferably 80°C to 100°C;

[0068] and / or,

[0069] The dosage of the inorganic matter can be 25-50% by weight of the organic matter particles, preferably 30-40%;

[0070] The inorganic matter can be at least one of calcium carbonate, fly ash, bentonite or silica, preferably at least one of calcium carbonate and silica; preferably the inorganic matter is inorganic matter particles, and its particle size can be 50-300 mesh, preferably 100-200 mesh. The specific inorganic matter can be selected from at least one of calcium carbonate, fly ash, bentonite or silica with a particle size of 50-300 mesh; preferably at least one of calcium carbonate and silica with a particle size of 100-200 mesh.

[0071] and / or,

[0072] The ball milling time can be 5-60 minutes, preferably 15-40 minutes.

[0073] The third object of the present invention is to provide a product prepared by the preparation method described in the second object of the present invention.

[0074] The fourth object of the present invention is to provide the application of the hydrophobic flocculant or the product prepared by the preparation method described above. Specifically, such as the application in underwater non-dispersible cement slurry, for example, the application in underwater non-dispersible consolidated plugging slurry for drilling plugging.

[0075] The effects of the present invention

[0076] The hydrophobic flocculant described in the present invention comprises a hydrophobic polymer obtained by free radical polymerization. This hydrophobic polymer is an amphoteric polymer, with both positive and negative charge groups on the polymer chain. It not only has the functions of electrical neutralization and adsorption bridging, but also has the function of entanglement and wrapping between molecules. In addition, a variety of monomers with sulfonic acid groups are introduced, making the polymer have good salt and temperature resistance performance.

[0077] The hydrophobic flocculant disclosed in the present invention has excellent performance. The cement slurry formulated with it as the key treatment agent has excellent anti-water dispersion characteristics. Its solid-phase particles can resist the impact of external water under the entanglement of the hydrophobic flocculant, and its anti-water erosion ability is significantly stronger than that of ordinary cement slurry systems. When the prepared cement slurry is poured into hot water at 80 °C, the cement slurry does not disperse, the boundary between the slurry and the water phase is clear, the water phase water quality is clear, and the initial consistency is lower than 30 Bc, meeting the on-site pumping requirements. The thickening time of the cement slurry at 80-160 °C can be adjusted within 3-6 h, without obvious retardation effect, and has no adverse effect on the thickening time and the strength of the cement stone, meeting the technical requirements for plugging deep water layers in oil drilling. Description of the Drawings

[0078] Figure 1 It is a diagram showing the situation of the conventional cement plugging slurry prepared for Comparative Example 2 added to room temperature water. Specifically, it can be seen that the conventional cement plugging slurry is washed away by water after being added to room temperature water.

[0079] Figure 2-1 、 2-2 、2-3, 2-4, 2-5, 2-6 are diagrams showing the situation of the underwater non-dispersible consolidated plugging slurry prepared with the hydrophobic flocculant described in Example 4 of the present application poured into hot water ( Figure 2-1 、 2-2 、2-3, 2-4, 2-5, 2-6 are diagrams showing the situation changing with time during the pouring process in sequence). It can be seen that the boundary between the underwater non-dispersible consolidated plugging slurry and the water layer is clear, and the slurry is not diluted by hot water. In water with a lower temperature, due to the weakened thermal movement of water molecules, the water cannot dilute the slurry either.

[0080] Figure 3 It is the thickening time diagram of the underwater non-dispersible consolidated plugging slurry prepared with the hydrophobic flocculant described in Example 4 of the present application. Detailed Embodiments

[0081] The present invention will be specifically described below in combination with specific embodiments. It is necessary to point out here that the following embodiments are only used for further illustration of the present invention, and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0082] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0083] Raw material source

[0084] If there are no special limitations on the raw materials used in the examples and comparative examples, they are all disclosed in the prior art. For example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0085] 2 - acrylamido - 2 - methylpropanesulfonic acid: Shouguang Runde Chemical Co., Ltd.

[0086] Acrylamide: Shandong Baomo Biochemical Co., Ltd.

[0087] N - vinylformamide: Tokyo Chemical Industry Co., Ltd. (TCI), Japan

[0088] Acrylic acid: Yangzi Petrochemical - BASF Co., Ltd.

[0089] Methyl methacrylate: Tianjin Guangfu Fine Chemical Co., Ltd.

[0090] Xanthan gum: Zibo Zhongxuan Biochemical Co., Ltd.

[0091] β - cyclodextrin: Zibo Qianhui Biotechnology Co., Ltd.

[0092] Poly - anionic cellulose (HV - PAC): Shandong Yiteng New Materials Co., Ltd.

[0093] Ammonium persulfate: Sinopharm Chemical Reagent Co., Ltd.

[0094] Sodium bisulfite: Sinopharm Chemical Reagent Co., Ltd.

[0095] Tetramethylethylenediamine: Sinopharm Chemical Reagent Co., Ltd.

[0096] Disodium ethylenediaminetetraacetate: Sinopharm Chemical Reagent Co., Ltd.

[0097] Calcium carbonate: Sinopharm Chemical Reagent Co., Ltd.

[0098] Silicon dioxide: Sinopharm Chemical Reagent Co., Ltd.

[0099] G - grade oil well cement is the cement sold by Sichuan Jiahua

[0100] Fly ash, the particle size of the fly ash is 0.5 - 300 μm, Qingfeng County Longxiang Co., Ltd.

[0101] The water reducing agent is the sulfonated aldehyde ketone condensate DZS produced by the Sinopec Research Institute of Petroleum Engineering Technology

[0102] Example 1:

[0103] (1) Add 10 g of N-vinylformamide, 6 g of acrylamide, 74 g of 2-acrylamido-2-methylpropane sulfonic acid, 2.5 g of acrylic acid, and 12.5 g of methyl methacrylate to 150 g of deionized water, and adjust the pH value to 8 with 40 g of 40% sodium hydroxide solution to obtain a mixed solution A. The total concentration of monomers in the mixed solution A is 35.6%

[0104] (2) Add 0.3 g of xanthan gum to the mixed solution A, and pass N2 for 0.5 hours to obtain a mixed solution B, where the xanthan gum is 0.1% of the weight of the mixed solution B.

[0105] (3) Add 0.1 g of ammonium persulfate as the initiator, 0.05 g of sodium bisulfite, and 0.3 g of ethylenediaminetetraacetic acid disodium as the complexing agent to the mixed solution B at 50 °C, and react for 3 hours to obtain a gel-like product, where the initiator dosage is 0.1% of the total weight of the monomers; ethylenediaminetetraacetic acid disodium is 0.1% of the weight of the mixed solution B;

[0106] (4) Cut and granulate the gel-like product, dry it at 85 °C for 10 hours, and then ball-mill it with 100-mesh calcium carbonate accounting for 30% of the organic matter mass for 30 minutes to obtain the hydrophobic flocculant ① for oil well cement, and the product particle size is in the fineness level of 200 - 300 mesh.

[0107] Example 2:

[0108] (1) Add 20 g of N-vinylformamide, 5 g of acrylamide, 70 g of 2-acrylamido-2-methylpropane sulfonic acid, 3 g of acrylic acid, and 18 g of methyl methacrylate to 100 g of deionized water, and adjust the pH value to 8 with 48 g of 40% sodium hydroxide solution to obtain a mixed solution A. The total concentration of monomers in the mixed solution A is approximately 43.9%

[0109] [ (2) Add 4 g of polyanionic cellulose (HV-PAC) to the mixed solution A, and pass N2 for 1 hour to obtain a mixed solution B, where the polyanionic cellulose (HV-PAC) is 1.52% of the weight of the mixed solution B.

[0110] (3) Add 0.1 g of ammonium persulfate as the initiator, 0.05 g of sodium bisulfite, and 0.3 g of ethylenediaminetetraacetic acid disodium as the complexing agent to the mixed solution B at 30 °C, and react for 5 hours to obtain a gel-like product, where the initiator dosage is 0.1% of the total weight of the monomers; ethylenediaminetetraacetic acid disodium is 0.13% of the weight of the mixed solution B;

[0111] (4) Shear granulate the gel-like product, dry it at 90 °C for 8 hours, and then ball mill it with 100-mesh calcium carbonate accounting for 35% of the mass of the organic matter for 30 minutes to obtain the hydrophobic flocculant ② for oil well cement, and the product particle size is at the fineness level of 200 - 300 mesh.

[0112] Example 3:

[0113] (1) Add 10 g of N-vinylformamide, 10 g of acrylamide, 75 g of 2-acrylamido-2-methylpropane sulfonic acid, 2 g of acrylic acid, and 12 g of methyl methacrylate to 200 g of deionized water, and adjust the pH value to 7 with 40 g of 40% sodium hydroxide solution to obtain the mixed solution A. The total concentration of monomers in the mixed solution A is 31.2%.

[0114] (2) Add 5 g of β-cyclodextrin to the mixed solution A, and pass N₂ for 1.5 hours under stirring until the β-cyclodextrin is completely dissolved to obtain the mixed solution B, where the β-cyclodextrin is 1.43% of the weight of the mixed solution B.

[0115] (3) Add 0.1 g of ammonium persulfate as the initiator, 0.05 g of sodium bisulfite, and 0.5 g of ethylenediaminetetraacetic acid disodium as the complexing agent to the mixed solution B at 60 °C, and react for 7 hours to obtain the gel-like product. The amount of the initiator is 0.1% of the total weight of the monomers; ethylenediaminetetraacetic acid disodium is 0.15% of the weight of the mixed solution B;

[0116] (4) Shear granulate the gel-like product, dry it at 90 °C for 8 hours, and then ball mill it with 100-mesh silica accounting for 33% of the mass of the organic matter for 20 minutes to obtain the hydrophobic flocculant ③ for oil well cement, and the product particle size is at the fineness level of 200 - 300 mesh.

[0117] Example 4:

[0118] (1) Add 30 g of N-vinylformamide, 5 g of acrylamide, 55 g of 2-acrylamido-2-methylpropane sulfonic acid, 7 g of acrylic acid, and 20 g of methyl methacrylate to 150 g of deionized water, and adjust the pH value to 7 with 38 g of 40% sodium hydroxide solution to obtain the mixed solution A. The total concentration of monomers in the mixed solution A is 38.3%.

[0119] (2) Add 0.5 g of xanthan gum to the mixed solution A, and pass N₂ for 1 hour to obtain the mixed solution B, where the xanthan gum is 0.16% of the weight of the mixed solution B.

[0120] (3) Add 0.1 g of ammonium persulfate as the initiator, 0.05 g of tetramethylethylenediamine, and 0.2 g of ethylenediaminetetraacetic acid disodium as the complexing agent to the mixed solution B at 30 °C, and react for 8 hours to obtain the gel-like product. The amount of the initiator is 0.1% of the total weight of the monomers; ethylenediaminetetraacetic acid disodium is 0.07% of the weight of the mixed solution B;

[0121] (4) Shear granulate the gel-like product, dry it at 95 °C for 8 hours, and then ball mill it with 100-mesh silica accounting for 36% of the mass of the organic matter for 20 minutes to obtain the hydrophobic flocculant ④ for oil well cement. The product has a fineness level of 200 - 300 mesh.

[0122] Example 5:

[0123] (1) Add 20 g of N-vinylformamide, 5 g of acrylamide, 70 g of 2-acrylamido-2-methylpropanesulfonic acid, 3 g of acrylic acid, and 2 g of methyl methacrylate to 100 g of deionized water, and adjust the pH value to 8 with 25 g of 25% ammonia water to obtain the mixed solution A. The total concentration of monomers in the mixed solution A is 48.1%.

[0124] (2) Add 0.3 g of xanthan gum to the mixed solution A, and pass N2 for 1 hour to obtain the mixed solution B, where the xanthan gum is 0.20% of the weight of the mixed solution B.

[0125] (3) Add 0.1 g of ammonium persulfate as the initiator, 0.03 g of tetramethylethylenediamine, and 0.2 g of ethylenediaminetetraacetic acid disodium as the complexing agent to the mixed solution B at 40 °C, and react for 8 hours to obtain the gel-like product. The dosage of the initiator is 0.06% of the total weight of the monomers; ethylenediaminetetraacetic acid disodium is 0.09% of the weight of the mixed solution B;

[0126] (4) Shear granulate the gel-like product, dry it at 90 °C for 8 hours, and then grind it with 100-mesh calcium carbonate accounting for 33% of the mass of the organic matter for 30 minutes to obtain the hydrophobic flocculant ⑤ for oil well cement. The product has a fineness level of 200 - 300 mesh.

[0127] Comparative Example 1:

[0128] Use the associative polymer produced by Sichuan Guangya Polymer Chemical Co., Ltd. (Sichuan Guangya, self-numbered ZND-2) as the hydrophobic flocculant, labeled as hydrophobic flocculant ⑥.

[0129] Comparative Example 2:

[0130] Conventional cement plugging slurry is prepared with G-class oil well cement and water at a water-cement ratio (mass ratio of water to cement) of 0.5.

[0131] Comparative Example 3:

[0132] Shear granulate the gel-like product synthesized in Example 1 of this example, without adding inorganic substances such as silica or ultrafine calcium, but directly ball mill it to a fineness level of 200 - 300 mesh, denoted as intermediate product 1.

[0133] Comparative Example 4:

[0134] The gel-like product synthesized in Example 2 of the present invention is used for shear granulation. Instead of adding inorganic substances such as silica or ultrafine calcium, it is directly ball-milled to a fineness level of 200-300 mesh, denoted as Intermediate Product 2.

[0135] Comparative Example 5:

[0136] The gel-like product synthesized in Example 3 of the present invention is used for shear granulation. Instead of adding inorganic substances such as silica or ultrafine calcium, it is directly ball-milled to a fineness level of 200-300 mesh, denoted as Intermediate Product 3.

[0137] Performance Test Example

[0138] Preparation and Test of Underwater Non-dispersible Consolidating Plugging Slurry

[0139] Using the hydrophobic flocculants ①-⑤ prepared in Examples 1-5, the hydrophobic flocculant ⑥ of Comparative Example 1, and the intermediate products 1-3 of Comparative Examples 3-5, underwater non-dispersible cement slurries for drilling plugging are respectively prepared, which are specifically made from raw materials containing the following parts by mass: 195 g of water, 300 g of G-class oil well cement, 90 g of fly ash, 8 g of water reducing agent USZ, and 19.5 g of hydrophobic flocculant.

[0140] The preparation method of the underwater non-dispersible consolidating plugging slurry for drilling plugging: Add the water reducing agent to water and stir at high speed. At the same time, slowly add the dry-mixed and evenly mixed oil well cement, fly ash, and hydrophobic flocculant into the high-speed stirred water phase, and stir evenly to obtain the underwater non-dispersible consolidating plugging slurry.

[0141] Performance test

[0142] 1. Underwater Non-dispersible Test

[0143] The underwater non-dispersible test method is as follows: Add 200 ml of normal temperature water or 80 °C hot water into a 500 ml transparent open beaker. Pour the prepared conventional cement slurry or underwater non-dispersible consolidating plugging slurry into the beaker at a height of 15 cm from the water surface in the beaker. The amount of the poured cement slurry and plugging slurry is controlled at 150-200 ml, and the pouring speed is controlled at 30-50 ml / s.

[0144] When ordinary cement slurry or cement-containing consolidated plugging slurry is poured into water, it will be quickly diluted by water into a cloud-like state, and the liquid in the glass cup is turbid as a whole. When the conventional cement plugging slurry prepared in Comparative Example 2 is added to normal temperature water, it can be seen that it is washed away by water (please see the attachment Figure 1 ); When the underwater non-dispersible consolidating plugging slurry prepared with the hydrophobic flocculant described in Example 4 of the present application is poured into 80 °C hot water, it can be seen that the underwater non-dispersible consolidating plugging slurry prepared with the hydrophobic flocculant described in the present application still has a clear interface even when poured into hot water with a stronger dispersion and dilution effect (please see the attachment Figure 2-1 、2-2 (2-3, 2-4, 2-5, 2-6). The poured cement slurry flows into the bottom of the cup in a slurry column and quickly spreads on the bottom of the cup. The boundary between the poured cement slurry and the water body is clear. Without strong agitation, the cement slurry will not mix with the water phase, and the water in the cup is clear.

[0145] 2. Performance Test of Underwater Non-dispersible Consolidating Leakage Stopping Slurry

[0146] For the density, initial consistency, thickening time, etc. of the underwater non-dispersible consolidating leakage stopping slurries prepared in Comparative Examples 1, 3-5 and the embodiments of the present invention, the tests are carried out in accordance with GB / T 19139-2012 "Test Methods for Oil Well Cement". (Among them Figure 3 is the thickening time of the underwater non-dispersible consolidating leakage stopping slurry prepared with the hydrophobic flocculant described in Example 4 of the present application). Other performances are determined according to the following methods.

[0147] The anti-dispersion property in 80°C hot water is tested according to the pouring method 15 cm above the water surface as described above. If the interface is clean and there are no solid particles such as oil well cement in the water phase, its anti-dispersion property in 80°C hot water is recorded as good; if the water phase has a slight color change and a small part of the solid particles such as oil well cement diffuses into the water phase, then its anti-dispersion property in 80°C hot water is recorded as good; if the color of the water phase becomes darker, a large part of the solid particles such as oil well cement diffuses into the water phase, or the two are mixed into one phase, then its anti-dispersion property in 80°C hot water is recorded as poor.

[0148] According to GB / T 19139-2012 "Test Methods for Oil Well Cement", using its standard strength test mold with the bottom closed, first apply butter in the mold, then fill the mold with water, pour the prepared comparative example and underwater non-dispersible cement leakage stopping slurry into the mold filled with water, drain the water in the mold, and stop pouring when all the water is drained or the leakage stopping slurry can be seen overflowing from the mold. Cover the upper cover plate of the mold, place it in a 60°C water bath and a 160°C curing kettle for 24 h, then take it out and cool it down to room temperature, demold and remove the test piece, and test its compressive strength with a universal material testing machine, which is recorded as the underwater curing compressive strength. Using the same mold, first apply butter in the mold without adding water, pour the prepared comparative example and underwater non-dispersible consolidating leakage stopping slurry into the mold, cover the upper cover plate of the mold, place it in a 60°C water bath and a 160°C curing kettle for 24 h, then take it out and cool it down to room temperature, demold and remove the test piece, and test its compressive strength with a universal material testing machine, which is recorded as the onshore curing compressive strength. The test results are shown in Table 1.

[0149] Table 1 Performance Test Results of Underwater Non-dispersible Consolidating Leakage Stopping Slurry for Drilling Leakage Stopping

[0150]

[0151] As can be seen from Table 1, although Comparative Examples 3-5 have good underwater non-dispersing properties, their fluidity is relatively small, the initial consistency is greater than 30 Bc, and serious retardation phenomena occur in the thickening experiments, and the thickening time is greater than 6 h, which is extremely unfavorable for on-site construction. However, the fluidity of the underwater non-dispersing cement slurry prepared with the hydrophobic flocculant described in this application as the main agent is greatly improved, the initial consistency is reduced to below 30 Bc, the pressure required for pumping is reduced, and the retardation effect of the existing materials on the cement slurry is overcome, and the strength of the cured cement stone is less affected.

[0152] In addition, from Figure 3 it can be seen that the initial consistency of the underwater non-dispersing consolidation plugging slurry prepared by the present invention is about 30 Bc. After the temperature rises to 60 °C, the consistency is basically stable between 25-28 Bc. After 290 minutes, the consistency increases rapidly and reaches the thickening end point. The thickening curve shows an obvious right-angled thickening characteristic, which is beneficial to improving the plugging success rate of water-bearing formations.

Claims

1. A hydrophobic flocculant comprising a mixture of inorganic powder and organic powder; The weight of the inorganic powder is 25-50% of the weight of the organic powder; The average particle size of the inorganic powder and the organic powder is 100 to 500 mesh; The inorganic powder is selected from at least one of calcium carbonate, fly ash, bentonite or silicon dioxide; the organic powder is from an organic polymer; The organic polymer is obtained by polymerizing the following components in weight percentage: N-vinylamide monomer 5-40%; Acrylamide monomer 4-30%; 40-85% vinyl-containing sulfonic acid monomer; Acrylic monomer 2-20%; Methacrylate monomer 1 to 30%.

2. The hydrophobic flocculant according to claim 1, characterized in that: The weight of the inorganic powder is 30-40% of the weight of the organic powder.

3. The hydrophobic flocculant according to claim 1, characterized in that: The average particle size of the inorganic powder and the organic powder is 200-400 meshes.

4. The hydrophobic flocculant according to claim 1, characterized in that: The inorganic powder is selected from at least one of calcium carbonate and silicon dioxide.

5. The hydrophobic flocculant according to claim 1, characterized in that: The organic polymer is obtained by polymerizing the following components in weight percentage: N-vinylamide monomers 7-30%; Acrylamide monomer 4-20%; 50-70% vinyl-containing sulfonic acid monomer; Acrylic monomer 2-10%; Methacrylate monomer 10-25%.

6. The hydrophobic flocculant according to claim 1, characterized in that: The N-vinylamide monomer is selected from at least one of N-vinylformamide, N-vinylacetamide and N-methyl-N-vinylacetamide; and / or, The acrylamide monomer is selected from at least one of acrylamide, N,N-dimethylacrylamide or N,N-diethylacrylamide.

7. The hydrophobic flocculant according to claim 1, characterized in that: The vinyl-containing sulfonic acid monomer is selected from at least one of 2-acrylamido-2-methylpropanesulfonic acid and 2-acryloyloxy-2-methylpropanesulfonic acid; and / or, The acrylic monomer is selected from at least one of acrylic acid and methacrylic acid; and / or, The methacrylate monomer is selected from at least one of methyl methacrylate, ethyl methacrylate, propyl methacrylate or butyl methacrylate.

8. The method for preparing a hydrophobic flocculant according to any one of claims 1 to 7, characterized in that The following steps are involved: The hydrophobic flocculant is prepared by ball-milling the organic polymer and the inorganic substance.

9. The method for preparing a hydrophobic flocculant according to claim 8, wherein: Before ball milling, the organic polymer is dried and crushed to obtain organic particles, and then the organic particles are ball milled with inorganic matter to obtain the hydrophobic flocculant.

10. The method for preparing a hydrophobic flocculant according to claim 9, characterized in that: The drying temperature is 70°C to 120°C.

11. The method for preparing a hydrophobic flocculant according to claim 8, characterized in that: The preparation method of the organic polymer comprises the following steps: The method is obtained by subjecting components including the N-vinylamide monomer, acrylamide monomer, vinyl-containing sulfonic acid monomer, acrylic acid monomer, and methacrylate monomer to free radical polymerization in a polymer material solution; the polymer material is selected from at least one of xanthan gum, polyanionic cellulose, cyclodextrin, and starch.

12. The method for preparing a hydrophobic flocculant according to claim 11, characterized in that: The preparation method of the organic polymer comprises the following steps: (1) adding the N-vinylamide monomer, acrylamide monomer, vinyl-containing sulfonic acid monomer, acrylic acid monomer, and methacrylate monomer to water, and adjusting the pH value of the solution to obtain a mixed solution A; (2) Adding polymer material to mixed solution A and passing nitrogen gas to obtain mixed solution B; (3) Add an initiator and a complexing agent to the mixed solution B to react and obtain a gel product.

13. The method for preparing a hydrophobic flocculant according to claim 12, wherein: In the step (1), The pH value of the adjusting solution is adjusted to be between 6 and 10; and / or, The total weight concentration of monomers in the mixed solution A is 10-50%.

14. The method for preparing a hydrophobic flocculant according to claim 13, wherein: In the step (1), The pH value of the adjusting solution is 7 to 9; and / or, The total weight concentration of monomers in the mixed solution A is 20-50%.

15. The method for preparing a hydrophobic flocculant according to claim 12, wherein: In the step (2), The weight of the polymer material is 0.05-3% of the weight of the mixed solution A.

16. The method for preparing a hydrophobic flocculant according to claim 15, characterized in that: In the step (2), The weight of the polymer material is 0.1-2% of the weight of the mixed solution A.

17. The method for preparing a hydrophobic flocculant according to claim 12, characterized in that: In the step (3), The initiator is an oxidation-reduction initiator; wherein the oxidizing agent is at least one of hydrogen peroxide, ammonium persulfate, and potassium persulfate, and the reducing agent is at least one of sodium bisulfite or tetramethylethylenediamine; and / or, The amount of the oxidant is 0.1% to 0.8% of the total weight of all monomers; The molar ratio of the reducing agent to the oxidizing agent is between (0.8-1):

1.

18. The method for preparing a hydrophobic flocculant according to claim 17, wherein: The amount of the oxidant used is 0.1% to 0.7% of the total weight of all monomers.

19. The method for preparing a hydrophobic flocculant according to claim 18, characterized in that: The amount of the oxidant used is 0.3% to 0.7% of the total weight of all monomers.

20. The method for preparing a hydrophobic flocculant according to claim 12, wherein: In the step (3), The amount of the complexing agent is 0.03-0.2% by weight of the mixed solution B; and / or, The complexing agent is an organic amine complexing agent.

21. The method for preparing a hydrophobic flocculant according to claim 20, characterized in that: In the step (3), The amount of the complexing agent used is 0.05-0.1% by weight of the mixed solution B.

22. The method for preparing a hydrophobic flocculant according to claim 20, wherein: In the step (3), The complexing agent is disodium edetate.

23. The method for preparing a hydrophobic flocculant according to claim 12, wherein: In the step (3), The reaction temperature of the reaction is 30°C to 80°C; The reaction time of the reaction is 1 to 8 hours.

24. The method for preparing a hydrophobic flocculant according to claim 23, characterized in that: In the step (3), The reaction temperature of the reaction is 40°C to 70°C; The reaction time of the reaction is 2 to 6 hours.

25. The method for preparing a hydrophobic flocculant according to claim 8, wherein: The amount of the inorganic substance is 25 to 50% by weight of the organic polymer; The inorganic substance is at least one of calcium carbonate, fly ash, bentonite or silicon dioxide; the inorganic substance is inorganic particles, and the particle size is 50 to 300 mesh; and / or, The ball milling time is 5 to 60 minutes.

26. The method for preparing a hydrophobic flocculant according to claim 25, characterized in that: The amount of the inorganic substance is 30-40% by weight of the organic polymer; The inorganic substance is at least one of calcium carbonate and silicon dioxide.

27. The method for preparing a hydrophobic flocculant according to claim 25, characterized in that: The particle size of the inorganic particles is 100 to 200 meshes; and / or, The ball milling time is 15 to 40 minutes.

28. A product prepared by the method according to any one of claims 8 to 27.

29. Use of the hydrophobic flocculant according to any one of claims 1 to 7 or the product prepared by the preparation method according to any one of claims 8 to 27.

30. The use according to claim 29, characterized in that For use in underwater non-dispersible cement slurries.

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