Green multiple sustained-release biologically dispersed glue, preparation method and application

Abstract

The present application belongs to the technical field of oil field chemistry, and particularly relates to a green multiple slow-release biological dispersion glue, a preparation method and application. According to mass percentage, the green multiple slow-release biological dispersion glue comprises the following components: 0.2%-1% of a high molecular functional polymer, 0.3%-1% of a natural high molecular polymer, 0.5%-5% of polyethylene imine, 0.1%-1% of a biological crosslinking agent, 0.1%-0.5% of an inorganic crosslinking agent, 0.02%-0.2% of a selective delaying agent, 0.02-0.6% of a biological consolidation agent, 0.03%-0.12% of a heat stabilizer, 0.05-0.5% of an anti-oxidation and bacteriostatic agent, and the balance of water. The components are mixed to obtain a green multiple slow-release biological dispersion glue which is temperature-resistant, salt-tolerant, formaldehyde-free, chromium-free, low-toxicity and environmentally friendly. The green multiple slow-release biological dispersion glue is harmless to different reservoir matrices, and can meet the plugging needs of different channels such as fracture channels, dominant channels and secondary channels of medium-high permeability glutenite reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical technology, specifically relating to a green multi-stage slow-release biodispersant, its preparation method, and its application. Background Technology

[0002] Currently, due to the strong heterogeneity of oil reservoirs, long-term water-drive development, and strong injection and production, the injected water forms multi-directional flow at different levels in the formation, making it impossible to effectively utilize low-permeability reservoirs and resulting in a significant reduction in actual single-well oil production. Therefore, how to develop and manufacture green and environmentally friendly gel plugging agents to seal different types of flow channels and improve the sweep efficiency of low-permeability layers has become one of the key research directions for significantly improving the recovery rate.

[0003] Water shut-off and profile control technology is an important means to improve the effectiveness of water injection and tertiary oil recovery, achieve water control and oil stabilization, and enhance oil recovery. Water shut-off and profile control technologies mainly include mechanical water shut-off and chemical water shut-off methods. Chemical water shut-off has become the main production stabilization measure in oilfields both domestically and internationally. Polymer gels, composed of high-molecular polymers, crosslinking agents, and additives, are the most widely used and economically beneficial method among chemical water shut-off methods. Regarding the existing crosslinking systems of polymer gels, they are mainly divided into inorganic metal crosslinking agents and organic crosslinking agents. Inorganic metal crosslinking agents mainly use high-valence metal ions (Cr... 6+ Zr 4 + While widely used, organic crosslinking agents suffer from drawbacks such as short gelation time, poor temperature resistance, severe environmental pollution, and high toxicity. These agents primarily consist of liquid formaldehyde, phenolic resin prepolymers, and other liquid aldehyde derivatives. However, the high volatility, irritant properties, toxicity, and environmental pollution associated with liquid phenols and aldehydes severely limit their large-scale application in water shut-off. Therefore, selecting low-toxicity, formaldehyde-free, chromium-free, and environmentally friendly green crosslinking agents has become the core objective for future water shut-off in oil and water wells.

[0004] Chinese invention patent application CN111892918A discloses a gel-based profile control agent and its preparation method. The agent consists of agent A and agent B. Agent A comprises the following components by mass percentage: 16%-23% trivalent chromium salt, 10%-15% complexing agent, 1%-4% antioxidant, 1%-4% emulsifier, 4%-8% pH adjuster, 0.5%-1.5% retarder, and the balance being water. Agent B comprises the following components by mass percentage: 0.3%-0.5% polyacrylamide, and the balance being water. The presence of trivalent chromium salt poses a significant risk of toxicity and environmental damage.

[0005] Chinese invention patent application CN101531890A discloses a method for preparing a profile control agent using phenolic resin, organic chromium, glacial acetic acid, resorcinol, and polyacrylamide as raw materials. By adding different crosslinking agents, the gelation time of the profile control agent can be controlled during use, ranging from 8 to 48 hours; the gel strength is high, it is not easily broken, and the shelf life is 1-2 years. However, due to the presence of Cr in the organic chromium crosslinking agent... 3+ Cr 6+ During the gelation process, they transform into each other and are classified as heavy metal pollutants under the new environmental protection law, which seriously pollutes groundwater and deep soil, and is greatly affected by environmental protection restrictions.

[0006] Chinese invention patent application CN114517082A discloses a temperature- and salt-resistant black liquor phenolic gel profile control agent and its preparation method, relating to the field of oil and gas field profile control agent technology. The gel profile control agent comprises: alkaline cotton pulp black liquor, phenol, formaldehyde, and polyacrylamide. The mass ratio of alkaline cotton pulp black liquor to phenol is 2:1-1:1; the molar ratio of phenol to formaldehyde is 3.5-4:1; and the mass ratio of alkaline cotton pulp black liquor to polyacrylamide is 10-15:1. During preparation, alkaline cotton pulp black liquor and formaldehyde are alternately added to molten phenol to obtain a resin, which is then reacted with a polyacrylamide solution to form a gel. However, due to the strong irritant and toxic properties of the phenol and formaldehyde used, and their volatile liquid state, transportation is difficult.

[0007] Due to the existence of various inorganic crosslinking agents (with Cr) 3+ Traditional crosslinking agents (primarily formaldehyde and chromium) and organic crosslinking agents (organic chromium, phenolic, formaldehyde) suffer from drawbacks such as high toxicity, significant environmental harm, volatility, and inconvenient transportation. Furthermore, polymer gels crosslinked with polymers exhibit short gelation times, poor long-term stability, severe reservoir pollution, and weak colloidal strength, failing to effectively block crosslinking pathways. Therefore, there is an urgent need to develop a formaldehyde- and chromium-free biodispersant with multiple delayed crosslinking effects, stable properties, and non-toxicity and environmental friendliness. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a green multi-stage slow-release biodispersible adhesive and its preparation method. This green multi-stage slow-release biodispersible adhesive possesses advantages such as good multi-crosslinking delay, good environmental friendliness, good viscoelasticity (>150Pa), good biodegradability, strong deep migration and plugging ability (plugging rate of over 99%), and adjustable gelation time (2h-8h). It does not damage the matrix of different reservoirs and can meet the plugging needs of different channels such as fracture channels, dominant channels, and secondary channels in medium-to-high permeability sandstone and conglomerate reservoirs.

[0009] To achieve the above-mentioned objectives of this invention, the specific technical solution adopted by this invention is as follows:

[0010] This invention provides a green, multi-stage, sustained-release biodispersible gel, comprising the following components by weight percentage:

[0011] High molecular functional polymers, 0.2%-1%; natural high molecular polymers, 0.3%-1%; polyethyleneimine, 0.5%-5%; bio-crosslinking agent, 0.1%-1%; inorganic crosslinking agent, 0.1%-0.5%; selective retardant, 0.02%-0.2%; bio-solidifier, 0.02%-0.6%; heat stabilizer, 0.03%-0.12%; antioxidant and antibacterial agent, 0.05%-0.5%; water, balance.

[0012] Preferably, by mass percentage, the functional polymer comprises 30%-50% sodium caseinate, 10%-20% hydrophobic associative polymer, and 30%-60% sodium polyacrylate.

[0013] More preferably, the viscosity-average molecular weights of the sodium caseinate, the hydrophobic associative polymer, and the sodium polyacrylate are 80,000-350,000, 15,000,000-30,000,000, and 5,000,000-15,000,000, respectively.

[0014] More preferably, the monomer in the hydrophobic associative polymer is selected from one or more of N-dodecylacrylamide, N-hexadecylacrylamide, N-phenylethylacrylamide, and tetramethylethylenediamine dibromide.

[0015] Preferably, the raw materials of the natural polymer, by mass percentage, include 30%-40% carboxymethyl xylan, 20%-30% konjac glucomannan, and 30%-50% carboxymethyl coumarin.

[0016] More preferably, the viscosity-average molecular weights of the carboxymethyl xylan, konjac glucomannan, and carboxymethyl coumarin are 15-20 million, 10-30 million, and 15-20 million, respectively.

[0017] Preferably, the viscosity-average molecular weight of the polyethyleneimine is 3-5 million.

[0018] Preferably, the bio-crosslinking agent comprises, by weight percentage, 20%-30% potassium humate, 30%-40% sodium hyaluronate, and 30%-50% sodium alginate.

[0019] More preferably, the number average molecular weights of the sodium hyaluronate and sodium alginate are 500,000-700,000 Daltons and 32,000-250,000 Daltons, respectively.

[0020] Preferably, the inorganic crosslinking agent comprises, by mass percentage, 30%-50% sodium alginate, 10%-20% potassium pentaborate, and 30%-60% disodium edetate.

[0021] More preferably, the sodium alginate has a viscosity-average molecular weight of 50,000 to 70,000.

[0022] Preferably, the selective retarder comprises, by weight percentage, 20%-40% sodium carbamate, 10%-30% potassium sorbate, and 30%-70% sodium glycinate.

[0023] Preferably, the bio-strengthening agent comprises, by weight percentage, 10%-30% elm bark powder, 30%-50% guar gum powder, and 20%-60% bay leaf powder.

[0024] Preferably, the heat stabilizer comprises, by weight percentage, 30%-50% 2-methylimidazolium-1-ethylurea, 20%-30% sodium octenyl succinate starch, and 20%-50% potassium metaborate.

[0025] Preferably, the antioxidant and antibacterial agent comprises, by weight percentage, 20%-40% sodium dichloroisocyanurate, 20%-30% sodium perborate, and 30%-60% potassium ferrate.

[0026] This invention also relates to a method for preparing the above-mentioned green multi-release biodispersible gel, comprising the following steps:

[0027] (1) Mix the functional polymer powder and the natural polymer powder and dissolve them in water to obtain a polymer-based liquid;

[0028] (2) Add polyethyleneimine, biological crosslinking agent and inorganic crosslinking agent to the polymer base liquid respectively, and stir to obtain a polymer crosslinking solution;

[0029] (3) Dissolve the selective retardant, heat stabilizer and antioxidant antibacterial agent in water to prepare a uniform and stable dispersion.

[0030] (4) Mix the polymer crosslinking solution and dispersion, add bio-solidifier, and after the polymerization reaction occurs, obtain green multi-release bio-dispersible gel.

[0031] Preferably, the stirring speed in step (4) is 700-900 r / min, the stirring time is 20-30 min, and the reaction temperature is 30-120℃.

[0032] The present invention also relates to the application of the above-mentioned green multi-release biodispersant or the dispersant prepared by the above-mentioned dispersant preparation method in the field of oilfield profile control and water shut-off technology.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) This invention obtains a green multi-layer slow-release biodispersible gel that is temperature and salt resistant, formaldehyde and chromium free, low toxicity and environmentally friendly by selecting a variety of low-toxicity functional components and optimizing the ratio.

[0035] (2) In this invention, the use of functional polymers and natural polymers has a synergistic effect, which can effectively improve the blocking rate; the use of bio-crosslinking agents significantly improves the viscosity of the dispersion.

[0036] (3) This green multi-stage slow-release biodispersible gel has the advantages of good multi-crosslinking delay, good green environmental protection, good viscoelasticity (>150Pa), good biodegradability, strong deep migration and plugging ability (plugging rate of over 99%), and adjustable gelation time (2h-8h). It does not damage the matrix of different reservoirs and can meet the plugging needs of different channels such as fracture channels, dominant channels and secondary channels in medium and high permeability sandstone and conglomerate reservoirs. Detailed Implementation

[0037] The technical solutions in the embodiments of the present invention will be further described in detail below. The described embodiments are only a part of the present invention and are used to explain the present invention, but are not intended to limit the present invention. Therefore, other embodiments obtained by other people skilled in the art without creative labor are all within the protection scope of the present invention.

[0038] Sodium caseinate, hydrophobic associative polymer and sodium polyacrylate were all purchased from Aisen (Rudong) Chemical Co., Ltd.

[0039] Polyethyleneimine was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0040] Carboxymethyl xylan, konjac glucomannan, and carboxymethyl coumarin were all purchased from Beijing Hengju Chemical Group Co., Ltd.

[0041] Sodium hyaluronate, sodium alginate, and sodium alginate were all purchased from Sichuan Weikeqi Biotechnology Co., Ltd.

[0042] Elm bark powder (FDBL) and bay leaf powder (FDFG) were both purchased from Xi'an Feida Biotechnology Co., Ltd.

[0043] The guar gum powder was purchased from Nanjing Ximeno Biotechnology Co., Ltd.

[0044] Unless otherwise specified, the reagents used in the following examples are all conventional reagents in the art and are commercially available.

[0045] Example 1

[0046] A green, multi-stage, slow-release biodispersible gel comprises, by weight percentage: 1% high-molecular-weight functional polymer; 1% natural high-molecular-weight polymer; 2% polyethyleneimine; 1% biocrosslinking agent; 0.5% inorganic crosslinking agent; 0.2% selective retardant; 0.6% biosolidifier; 0.12% heat stabilizer; 0.5% antioxidant and antibacterial agent; and 93.08% water.

[0047] The high molecular weight functional polymer is a mixture of 30% sodium caseinate (viscosity average molecular weight of 350,000), 10% hydrophobic associative polymer (viscosity average molecular weight of 30 million, monomer of N-hexadecylacrylamide) and 60% sodium polyacrylate (viscosity average molecular weight of 15 million) by mass percentage.

[0048] The natural polymer is a mixture of 30% carboxymethyl xylan (viscosity-average molecular weight of 20 million), 20% konjac glucomannan (viscosity-average molecular weight of 30 million) and 50% carboxymethyl coumarin (viscosity-average molecular weight of 20 million).

[0049] Polyethyleneimine, with a viscosity-average molecular weight of 5 million;

[0050] The bio-crosslinking agent is a mixture of 20% potassium humate, 30% sodium hyaluronate (number average molecular weight of 700,000 Daltons) and 50% sodium alginate (number average molecular weight of 250,000 Daltons).

[0051] The inorganic crosslinking agent is a mixture of 30% sodium alginate (viscosity-average molecular weight of 70,000), 10% potassium pentaborate and 60% disodium edetate.

[0052] The selective retarder is a mixture of 20% sodium carbamate, 10% potassium sorbate and 70% sodium glycine;

[0053] The biological preservative is a mixture of 10% elm bark powder, 30% guar gum powder and 60% bay leaf powder;

[0054] The heat stabilizer is a mixture of 30% 2-methylimidazolium-1-ethylurea, 20% sodium octenyl succinate starch and 50% potassium metaborate;

[0055] The antioxidant and antibacterial agent is a mixture of 20% sodium dichloroisocyanurate, 20% sodium perborate, and 60% potassium ferrate.

[0056] The preparation method of the above-mentioned green multi-stage sustained-release biodispersible gel is as follows:

[0057] (1) Mix the functional polymer powder and the natural polymer powder and dissolve them in water to obtain a polymer-based liquid;

[0058] (2) Polyethyleneimine, biological crosslinking agent and inorganic crosslinking agent are added to the above solution respectively, and stirred evenly to obtain a polymer crosslinking solution;

[0059] (3) Dissolve the selective retardant, heat stabilizer and antioxidant antibacterial agent in water to prepare a uniform and stable dispersion.

[0060] (4) Mix the polymerization crosslinking solution and dispersion at 80℃, add the bio-solidifier, stir at 800r / min to carry out the polymerization reaction, and obtain green multi-release bio-dispersible gel after 30min.

[0061] Example 2

[0062] A green, multi-stage, slow-release biodispersible adhesive comprises, by weight percentage: 1% high-molecular-weight functional polymer; 0.8% natural high-molecular-weight polymer; 1% polyethyleneimine; 0.8% biocrosslinking agent; 0.4% inorganic crosslinking agent; 0.15% selective retardant; 0.4% biosolidifier; 0.08% heat stabilizer; 0.3% antioxidant and antibacterial agent; and 95.07% water.

[0063] The high molecular weight functional polymer is a mixture of 40% sodium caseinate (viscosity average molecular weight of 250,000), 15% hydrophobic associative polymer (viscosity average molecular weight of 20 million, monomer is N-phenylethyl acrylamide) and 45% sodium polyacrylate (viscosity average molecular weight of 10 million) by mass percentage.

[0064] The natural polymer is a mixture of 35% carboxymethyl xylan (viscosity-average molecular weight of 18 million), 25% konjac glucomannan (viscosity-average molecular weight of 15 million) and 40% carboxymethyl coumarin (viscosity-average molecular weight of 18 million).

[0065] Polyethyleneimine, with a viscosity-average molecular weight of 4 million;

[0066] The bio-crosslinking agent is a mixture of 25% potassium humate, 35% sodium hyaluronate (number average molecular weight of 600,000 Daltons) and 40% sodium alginate (number average molecular weight of 200,000 Daltons).

[0067] The inorganic crosslinking agent is a mixture of 40% sodium alginate (viscosity-average molecular weight of 60,000), 15% potassium pentaborate and 45% disodium edetate.

[0068] The selective retarder is a mixture of 30% sodium carbamate, 20% potassium sorbate and 50% sodium glycine;

[0069] The biological preservative is a mixture of 20% elm bark powder, 40% guar gum powder and 40% bay leaf powder;

[0070] The heat stabilizer is a mixture of 40% 2-methylimidazolium-1-ethylurea, 25% sodium octenyl succinate starch and 35% potassium metaborate.

[0071] The antioxidant and antibacterial agent is a mixture of 30% sodium dichloroisocyanurate, 35% sodium perborate and 45% potassium ferrate.

[0072] In this embodiment, the reaction conditions in step (4) are: stirring speed 900 r / min, stirring time 20 min, reaction temperature 120℃, and other preparation steps are the same as in Example 1.

[0073] Example 3

[0074] A green, multi-stage, sustained-release biodispersible gel comprises, by weight percentage: 0.5% high-molecular-weight functional polymer; 0.5% natural high-molecular-weight polymer; 1% polyethyleneimine; 0.4% biocrosslinking agent; 0.3% inorganic crosslinking agent; 0.08% selective retardant; 0.2% biosolidifier; 0.04% heat stabilizer; 0.1% antioxidant and antibacterial agent; and 96.88% water.

[0075] The high molecular weight functional polymer is a mixture of 50% sodium caseinate (viscosity average molecular weight of 80,000), 20% hydrophobic associative polymer (viscosity average molecular weight of 15 million, monomer of N-dodecylacrylamide) and 30% sodium polyacrylate (viscosity average molecular weight of 5 million) by mass percentage.

[0076] The natural polymer is a mixture of 40% carboxymethyl xylan (viscosity-average molecular weight of 15 million), 30% konjac glucomannan (viscosity-average molecular weight of 10 million) and 30% carboxymethyl coumarin (viscosity-average molecular weight of 15 million).

[0077] Polyethyleneimine, with a viscosity-average molecular weight of 3 million;

[0078] The bio-crosslinking agent is a mixture of 30% potassium humate, 40% sodium hyaluronate (number average molecular weight of 500,000 Daltons) and 30% sodium alginate (number average molecular weight of 150,000 Daltons).

[0079] The inorganic crosslinking agent is a mixture of 50% sodium alginate (viscosity-average molecular weight of 50,000), 20% potassium pentaborate and 30% disodium edetate.

[0080] The selective retarder is a mixture of 40% sodium carbamate, 30% potassium sorbate and 30% sodium glycine;

[0081] The biological stabilizer is a mixture of 30% elm bark powder, 50% guar gum powder and 20% bay leaf powder;

[0082] The heat stabilizer is a mixture of 50% 2-methylimidazolium-1-ethylurea, 30% sodium octenyl succinate starch and 20% potassium metaborate;

[0083] The antioxidant and antibacterial agent is a mixture of 40% sodium dichloroisocyanurate, 30% sodium perborate and 30% potassium ferrate.

[0084] In this embodiment, the reaction conditions in step (4) are: stirring speed 700 r / min, stirring time 30 min, reaction temperature 60℃, and other preparation steps are the same as in Example 1.

[0085] Example 4

[0086] A green, multi-stage, slow-release biodispersible gel comprises, by weight percentage: 0.6% high-molecular-weight functional polymer; 0.5% natural high-molecular-weight polymer; 2.5% polyethyleneimine; 0.5% bio-crosslinking agent; 0.25% inorganic crosslinking agent; 0.12% selective retardant; 0.3% bio-solidifier; 0.07% heat stabilizer; 0.3% antioxidant and antibacterial agent; and 94.86% water.

[0087] The high molecular weight functional polymer is a mixture of 30% sodium caseinate (viscosity average molecular weight of 80,000), 10% hydrophobic associative polymer (viscosity average molecular weight of 15 million, monomer is docosylallyltetramethylethylenediamine dibromide) and 60% sodium polyacrylate (viscosity average molecular weight of 5 million) by mass percentage.

[0088] The natural polymer is a mixture of 30% carboxymethyl xylan (viscosity-average molecular weight of 15 million), 20% konjac glucomannan (viscosity-average molecular weight of 10 million) and 50% carboxymethyl coumarin (viscosity-average molecular weight of 15 million).

[0089] Polyethyleneimine, with a viscosity-average molecular weight of 4 million;

[0090] The bio-crosslinking agent is a mixture of 20% potassium humate, 30% sodium hyaluronate (number average molecular weight of 500,000 Daltons) and 50% sodium alginate (number average molecular weight of 100,000 Daltons).

[0091] The inorganic crosslinking agent is a mixture of 30% sodium alginate (viscosity-average molecular weight of 50,000), 10% potassium pentaborate and 60% disodium edetate.

[0092] The selective retarder is a mixture of 20% sodium carbamate, 10% potassium sorbate and 70% sodium glycine;

[0093] The biological preservative is a mixture of 10% elm bark powder, 30% guar gum powder and 60% bay leaf powder;

[0094] The heat stabilizer is a mixture of 30% 2-methylimidazolium-1-ethylurea, 20% sodium octenyl succinate starch and 50% potassium metaborate;

[0095] The antioxidant and antibacterial agent is a mixture of 20% sodium dichloroisocyanurate, 20% sodium perborate, and 60% potassium ferrate.

[0096] In this embodiment, the reaction conditions in step (4) are: stirring speed of 900 r / min, stirring time of 30 min, reaction temperature of 30℃, and other preparation steps are the same as in Example 1.

[0097] Example 5

[0098] A green, multi-stage, sustained-release biodispersible gel comprises, by weight percentage: 0.5% high-molecular-weight functional polymer; 0.5% natural high-molecular-weight polymer; 1% polyethyleneimine; 0.4% biocrosslinking agent; 0.3% inorganic crosslinking agent; 0.08% selective retardant; 0.2% biosolidifier; 0.04% heat stabilizer; 0.1% antioxidant and antibacterial agent; and 96.88% water.

[0099] The high molecular weight functional polymer is a mixture of 40% sodium caseinate (viscosity average molecular weight of 300,000), 15% hydrophobic associative polymer (viscosity average molecular weight of 15 million, monomer of N-phenylethyl acrylamide) and 45% sodium polyacrylate (viscosity average molecular weight of 5 million) by mass percentage.

[0100] The natural polymer is a mixture of 35% carboxymethyl xylan (viscosity-average molecular weight of 15 million), 25% konjac glucomannan (viscosity-average molecular weight of 10 million) and 40% carboxymethyl coumarin (viscosity-average molecular weight of 15 million).

[0101] Polyethyleneimine, with a viscosity-average molecular weight of 3.5 million;

[0102] The bio-crosslinking agent is a mixture of 25% potassium humate, 35% sodium hyaluronate (number average molecular weight of 600,000 Daltons) and 40% sodium alginate (number average molecular weight of 32,000 Daltons).

[0103] The inorganic crosslinking agent is a mixture of 40% sodium alginate (viscosity-average molecular weight of 50,000), 15% potassium pentaborate and 45% disodium edetate.

[0104] The selective retarder is a mixture of 30% sodium carbamate, 20% potassium sorbate and 50% sodium glycine;

[0105] The biological preservative is a mixture of 20% elm bark powder, 40% guar gum powder and 40% bay leaf powder;

[0106] The heat stabilizer is a mixture of 40% 2-methylimidazolium-1-ethylurea, 25% sodium octenyl succinate starch and 35% potassium metaborate.

[0107] The preparation process of the green multi-release biodispersible gel in this embodiment is the same as that in Example 1.

[0108] Comparative Example 1

[0109] A green, multi-stage, slow-release biodispersible gel comprises, by weight percentage: 2% natural polymer; 2% polyethyleneimine; 1% biocrosslinking agent; 0.5% inorganic crosslinking agent; 0.2% selective retardant; 0.6% biosolidifier; 0.12% heat stabilizer; 0.5% antioxidant and antibacterial agent; and 93.08% water.

[0110] The natural polymer, by mass percentage, is a mixture of 30% carboxymethyl xylan (viscosity-average molecular weight of 20 million), 20% konjac glucomannan (viscosity-average molecular weight of 30 million), and 50% carboxymethyl coumarin (viscosity-average molecular weight of 20 million).

[0111] Polyethyleneimine, with a viscosity-average molecular weight of 5 million;

[0112] The bio-crosslinking agent is a mixture of 20% potassium humate, 30% sodium hyaluronate (number average molecular weight of 700,000 Daltons) and 50% sodium alginate (number average molecular weight of 250,000 Daltons).

[0113] The inorganic crosslinking agent is a mixture of 30% sodium alginate (viscosity-average molecular weight of 70,000), 10% potassium pentaborate and 60% disodium edetate.

[0114] The selective retarder is a mixture of 20% sodium carbamate, 10% potassium sorbate and 70% sodium glycine;

[0115] The biological preservative is a mixture of 10% elm bark powder, 30% guar gum powder and 60% bay leaf powder;

[0116] The heat stabilizer is a mixture of 30% 2-methylimidazolium-1-ethylurea, 20% sodium octenyl succinate starch and 50% potassium metaborate;

[0117] The antioxidant and antibacterial agent is a mixture of 20% sodium dichloroisocyanurate, 20% sodium perborate, and 60% potassium ferrate.

[0118] The preparation method of the above-mentioned green multi-stage sustained-release biodispersible gel is as follows:

[0119] (1) Dissolve natural polymer powder in water, then add polyethyleneimine, biological crosslinking agent and inorganic crosslinking agent, stir evenly to obtain polymer crosslinking solution;

[0120] (2) Dissolve the selective retardant, heat stabilizer and antioxidant antibacterial agent in water to prepare a uniform and stable dispersion.

[0121] (3) The polymerization crosslinking solution and dispersion were mixed at 80°C, and a bio-solidifier was added. The polymerization reaction was carried out by stirring at 800 r / min. After 30 min, a green multi-release bio-dispersible gel was obtained.

[0122] Comparative Example 2

[0123] A green, multi-stage, slow-release biodispersible gel comprises, by mass percentage: 2% high-molecular-weight functional polymer; 2% polyethyleneimine; 1% biocrosslinking agent; 0.5% inorganic crosslinking agent; 0.2% selective retardant; 0.6% biosolidifier; 0.12% heat stabilizer; 0.5% antioxidant and antibacterial agent; and 93.08% water.

[0124] The high molecular weight functional polymer is a mixture of 30% sodium caseinate (viscosity average molecular weight of 350,000), 10% hydrophobic associative polymer (viscosity average molecular weight of 30 million, monomer of N-hexadecylacrylamide) and 60% sodium polyacrylate (viscosity average molecular weight of 15 million) by mass percentage.

[0125] Polyethyleneimine, with a viscosity-average molecular weight of 5 million;

[0126] The bio-crosslinking agent is a mixture of 20% potassium humate, 30% sodium hyaluronate (number average molecular weight of 700,000 Daltons) and 50% sodium alginate (number average molecular weight of 250,000 Daltons).

[0127] The inorganic crosslinking agent is a mixture of 30% sodium alginate (viscosity-average molecular weight of 70,000), 10% potassium pentaborate and 60% disodium edetate.

[0128] The selective retarder is a mixture of 20% sodium carbamate, 10% potassium sorbate and 70% sodium glycine;

[0129] The biological preservative is a mixture of 10% elm bark powder, 30% guar gum powder and 60% bay leaf powder;

[0130] The heat stabilizer is a mixture of 30% 2-methylimidazolium-1-ethylurea, 20% sodium octenyl succinate starch and 50% potassium metaborate;

[0131] The antioxidant and antibacterial agent is a mixture of 20% sodium dichloroisocyanurate, 20% sodium perborate, and 60% potassium ferrate.

[0132] The preparation method of the above-mentioned green multi-stage sustained-release biodispersible gel is as follows:

[0133] (1) Dissolve the high molecular functional polymer powder in water, then add polyethyleneimine, biological crosslinking agent and inorganic crosslinking agent, and stir evenly to obtain a polymer crosslinking solution;

[0134] (2) Dissolve the selective retardant, heat stabilizer and antioxidant antibacterial agent in water to prepare a uniform and stable dispersion.

[0135] (3) The polymerization crosslinking solution and dispersion were mixed at 80°C, and a bio-solidifier was added. The polymerization reaction was carried out by stirring at 800 r / min. After 30 min, a green multi-release bio-dispersible gel was obtained.

[0136] Comparative Example 3

[0137] A green, multi-stage, slow-release biodispersible gel comprises, by weight percentage: 1% high-molecular-weight functional polymer; 1% natural high-molecular-weight polymer; 2% polyethyleneimine; 1.5% inorganic crosslinking agent; 0.2% selective retardant; 0.6% bio-solidifier; 0.12% heat stabilizer; 0.5% antioxidant and antibacterial agent; and 93.08% water.

[0138] The high molecular weight functional polymer is a mixture of 30% sodium caseinate (viscosity average molecular weight of 350,000), 10% hydrophobic associative polymer (viscosity average molecular weight of 30 million, monomer of N-hexadecylacrylamide) and 60% sodium polyacrylate (viscosity average molecular weight of 15 million) by mass percentage.

[0139] The natural polymer is a mixture of 30% carboxymethyl xylan (viscosity-average molecular weight of 20 million), 20% konjac glucomannan (viscosity-average molecular weight of 30 million) and 50% carboxymethyl coumarin (viscosity-average molecular weight of 20 million).

[0140] Polyethyleneimine, with a viscosity-average molecular weight of 5 million;

[0141] The inorganic crosslinking agent is a mixture of 30% sodium alginate (viscosity-average molecular weight of 70,000), 10% potassium pentaborate and 60% disodium edetate.

[0142] The selective retarder is a mixture of 20% sodium carbamate, 10% potassium sorbate and 70% sodium glycine;

[0143] The biological preservative is a mixture of 10% elm bark powder, 30% guar gum powder and 60% bay leaf powder;

[0144] The heat stabilizer is a mixture of 30% 2-methylimidazolium-1-ethylurea, 20% sodium octenyl succinate starch and 50% potassium metaborate;

[0145] The antioxidant and antibacterial agent is a mixture of 20% sodium dichloroisocyanurate, 20% sodium perborate, and 60% potassium ferrate.

[0146] The preparation method of the above-mentioned green multi-stage sustained-release biodispersible gel is as follows:

[0147] (1) Mix the functional polymer powder and the natural polymer powder and dissolve them in water to obtain a polymer-based liquid;

[0148] (2) Polyethyleneimine and inorganic crosslinking agent are added to the above solution respectively, and stirred evenly to obtain a polymerization crosslinking solution;

[0149] (3) Dissolve the selective retardant, heat stabilizer and antioxidant antibacterial agent in water to prepare a uniform and stable dispersion.

[0150] (4) Mix the polymerization crosslinking solution and dispersion at 80℃, add the bio-solidifier, stir at 800r / min to carry out the polymerization reaction, and obtain green multi-release bio-dispersible gel after 30min.

[0151] Effect evaluation

[0152] The dispersions prepared in Examples 1-5 and Comparative Examples 1-3 of this invention were tested.

[0153] The gelation time, viscosity and other parameters were determined according to the standard "SY / T 5590-2004 Performance Evaluation Method of Profile Modifier"; the viscoelasticity of the dispersion was determined according to the standard "SY / T 6296-1997 Determination of Strength of Polymer Gel for Oil Production - Rheological Parameter Method"; and the plugging rate was calculated by core displacement experiment. The test results are shown in Table 1.

[0154] Table 1. Test results of the properties of the green multi-release biodispersible gel in the examples and comparative examples.

[0155]

[0156]

[0157] As can be seen from the data in Table 1, the green multi-stage slow-release biodispersible gel of the present invention has the following advantages: good multi-crosslinking delay, good green environmental protection, good viscoelasticity (>150Pa), good biodegradability, strong deep migration and plugging ability (plugging rate of over 99%), and adjustable gelation time (2h-8h). It does not damage the matrix of different reservoirs and can meet the plugging needs of different channels such as fracture channels, dominant channels and secondary channels in medium- and high-permeability sandstone and conglomerate reservoirs.

[0158] This invention develops a green, multi-stage slow-release biodispersant system based on high-molecular polymers. By adding a preferred crosslinking agent, a high-viscosity dispersant system is formed, exhibiting a 10-fold increase in viscosity compared to conventional oil sludge suspension systems and a 30% improvement in core plugging rate. It effectively carries oil sludge into deep formations to plug medium- and high-permeability channels. Currently, this profile control system has been applied in the Che510 well area of ​​the No. 1 Oil Production Plant. From October to December 2022, four wells were successfully treated. To date, initial results have been observed in increasing oil production and reducing water cut, with a verified absolute increase of 270 tons of oil and a maximum reduction of 7 percentage points in water cut.

[0159] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A green, multi-stage, sustained-release biodispersible gel, characterized in that, The dispersion comprises, by weight percentage: 0.2%-1% high molecular functional polymer; Natural high molecular weight polymers, 0.3%-1%; Polyethyleneimine, 0.5%-5%; Bio-crosslinking agent, 0.1%-1%; Inorganic crosslinking agent, 0.1%-0.5%; Selective delay agent, 0.02%-0.2%; Biological stabilizing agent, 0.02-0.6%; Heat stabilizer, 0.03%-0.12%; Antioxidant and antibacterial agent, 0.05-0.5%; Water, remaining amount; By mass percentage, the raw materials of the functional polymer include 30%-50% sodium caseinate, 10%-20% hydrophobic associating polymer, and 30%-60% sodium polyacrylate; the monomers in the hydrophobic associating polymer are selected from one or more of N-dodecylacrylamide, N-hexadecylacrylamide, N-phenylethylacrylamide, and docosylallyltetramethylethylenediamine dibromide. By weight percentage, the raw materials of the natural polymer include 30%-40% carboxymethyl xylan, 20%-30% konjac glucomannan, and 30%-50% carboxymethyl coumarin; The raw materials of the bio-crosslinking agent, by mass percentage, include 20%-30% potassium humate, 30%-40% sodium hyaluronate, and 30%-50% sodium alginate; The inorganic crosslinking agent comprises, by mass percentage, 30%-50% sodium alginate, 10%-20% potassium pentaborate, and 30%-60% disodium edetate; The selective retarder comprises, by weight percentage, 20%-40% sodium carbamate, 10%-30% potassium sorbate, and 30%-70% sodium glycine; The raw materials of the bio-strengthening agent, by weight percentage, include 10%-30% elm bark powder, 30%-50% guar gum powder, and 20%-60% bay leaf powder; The heat stabilizer, by mass percentage, comprises 30%-50% 2-methylimidazolium-1-ethylurea, 20%-30% sodium octenyl succinate starch, and 20%-50% potassium metaborate; The raw materials of the antioxidant and antibacterial agent, by weight percentage, include 20%-40% sodium dichloroisocyanurate, 20%-30% sodium perborate, and 30%-60% potassium ferrate.

2. The green multi-stage slow-release biodispersant according to claim 1, characterized in that, The viscosity-average molecular weights of the sodium caseinate, the hydrophobic associative polymer, and the sodium polyacrylate are 80,000-350,000, 15,000,000-30,000,000, and 5,000,000-15,000,000, respectively.

3. The green multi-stage slow-release biodispersant according to claim 1, characterized in that, The viscosity-average molecular weights of the carboxymethyl xylan, konjac glucomannan, and carboxymethyl coumarin are 15-20 million, 10-30 million, and 15-20 million, respectively.

4. The green multi-stage slow-release biodispersant according to claim 1, characterized in that, The viscosity-average molecular weight of the polyethyleneimine is 3-5 million.

5. The green multi-stage slow-release biodispersant according to claim 1, characterized in that, The number average molecular weights of the sodium hyaluronate and sodium alginate are 500,000-700,000 Daltons and 32,000-250,000 Daltons, respectively.

6. The green multi-stage slow-release biodispersant according to claim 1, characterized in that, The viscosity-average molecular weight of the sodium alginate is 50,000-70,000.

7. A method for preparing a green multi-stage sustained-release biodispersible gel as described in any one of claims 1-6, characterized in that, Includes the following steps: (1) Mix the functional polymer powder and the natural polymer powder and dissolve them in water to obtain a polymer-based liquid; (2) Polyethyleneimine, biological crosslinking agent and inorganic crosslinking agent are added to the polymer base liquid respectively and stirred to obtain a polymer crosslinking solution; (3) Dissolve the selective retardant, heat stabilizer, and antioxidant antibacterial agent in water to obtain a uniform and stable dispersion; (4) Mix the polymer crosslinking solution and the dispersion, add the bio-solidifier, and after the polymerization reaction occurs, a green multi-release bio-dispersible gel is obtained.

8. The preparation method according to claim 7, characterized in that, The stirring speed in step (2) is 700-900 r / min, the temperature of the solution system is 30-120℃, and the stirring time is 20-30 min.

9. The application of the green multi-release biodispersant according to any one of claims 1-6 or the dispersant prepared by the preparation method according to any one of claims 7-8 in the field of oilfield profile control and water shut-off technology.

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