Cross-linking system and modifying and flooding agent

Abstract

The invention discloses a crosslinking system and a modifying and flooding agent, and belongs to the technical field of oil gas. The cross-linking system comprises a first cross-linking agent and a second cross-linking agent, the first cross-linking agent is prepared by the following method: in the presence of an accelerant and a basic catalyst, bisphenol A and formaldehyde react to prepare a hydroxymethylated phenolic prepolymer; uniformly mixing the hydroxymethylated phenolic prepolymer with a stabilizer to prepare a first cross-linking agent; the accelerant is selected from at least one of methanol, ethanol and isopropanol; the second cross-linking agent comprises a glue promoting agent and a deoxidant. The cross-linking system is suitable for reacting with polyacrylamide to generate a compact three-dimensional network structure, so that the temperature resistance and the salt resistance of the modifying and flooding agent are improved.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas technology, and in particular to a cross-linking system and a displacement agent. Background Art

[0002] Movable gel flooding is a technical measure of "controlling water and stabilizing oil". It can block high-permeability channels and force subsequent fluids to turn to low-permeability areas, thereby achieving liquid flow diversion, effectively improving the swept area of ​​injected water and increasing crude oil recovery.

[0003] At present, the crosslinking agents for movable gel displacement are mostly phenolic resin crosslinking agents, which are usually prepared by reacting phenol and aldehydes as raw materials, which makes the crosslinking agent have environmental problems and cannot meet the requirements of high-temperature reinjection water preparation. In order to improve the reaction activity of phenolic resin crosslinking agents at high temperature and high mineralization, as well as the environmental protection of phenolic resin crosslinking agents, the relevant technology provides a low-polyphenol resin crosslinking agent for oil field recovery enhancement, which is composed of bisphenol A, formaldehyde, catalyst solution, accelerator and enhancer. Bisphenol A with lower toxicity is used instead of phenol to participate in the reaction, which reduces the pollution to the environment during the synthesis and application of the crosslinking agent and improves its environmental protection.

[0004] However, the oligomeric polyphenol resin cross-linking agent is not suitable for the regulation and displacement requirements of high-temperature oil reservoirs at 80°C-130°C, has poor temperature resistance, and has a relatively complicated preparation process. Summary of the invention

[0005] In view of this, the present invention provides a cross-linking system and a control agent, which can solve the technical problems existing in the related technology.

[0006] Specifically, the following technical solutions are included:

[0007] In one aspect, a cross-linking system is provided, the cross-linking system comprising a first cross-linking agent and a second cross-linking agent;

[0008] The first crosslinking agent is prepared by the following method: in the presence of a promoter and an alkaline catalyst, bisphenol A and formaldehyde are reacted to prepare a hydroxymethylated phenolic prepolymer; the hydroxymethylated phenolic prepolymer and a stabilizer are uniformly mixed to prepare the first crosslinking agent;

[0009] Wherein, the accelerator is selected from at least one of methanol, ethanol and isopropanol;

[0010] The second cross-linking agent includes a gel promoter and an oxygen scavenger.

[0011] In some possible implementations, the step of reacting bisphenol A and formaldehyde in the presence of a promoter and a catalyst to prepare a hydroxymethylated phenolic prepolymer comprises:

[0012] At 40° C.-55° C. and under stirring conditions, the bisphenol A, the accelerator and the first part of the alkaline catalyst are uniformly mixed, the raw material system is heated to 60° C.-75° C., and the first part of the formaldehyde solution is added dropwise to the raw material system;

[0013] After the first part of the formaldehyde solution is added dropwise, the second part of the alkaline catalyst is added dropwise until the mixture is evenly mixed, and then the second part of the formaldehyde solution is added dropwise, followed by constant temperature reaction to prepare the hydroxymethylated phenolic prepolymer.

[0014] In some possible implementations, the mass of the first part of the alkaline catalyst accounts for 65%-80% of the total amount of the alkaline catalyst, and the second part of the alkaline catalyst is the remainder;

[0015] The mass of the first part of the formaldehyde solution is 65%-80% of the total amount of the formaldehyde solution, and the dropwise addition is completed within 8min-13min; the second part of the formaldehyde solution is the remainder, and the dropwise addition is completed within 8min-13min.

[0016] In some possible implementations, the alkaline catalyst is a mixture of sodium hydroxide and barium hydroxide, and the molar ratio of the sodium hydroxide to the barium hydroxide is 2-3:1.

[0017] In some possible implementations, the stabilizer is selected from at least one of anthranilic acid and p-aminobenzoic acid;

[0018] The weight ratio of the hydroxymethylated phenolic prepolymer to the stabilizer is 90:3-7.

[0019] In some possible implementations, the molar ratio of the gel promoter to the oxygen scavenger is 1-5:1.

[0020] In some possible implementations, the gel promoter is selected from ammonium chloride;

[0021] The deoxidizer is selected from at least one of thiourea, ammonium thiosulfate and sodium bisulfite.

[0022] In some possible implementations, the cross-linking system further includes a reinforcing agent, and the reinforcing agent is selected from at least one of nano-silicon dioxide, nano-titanium dioxide, and nano-calcium carbonate.

[0023] On the other hand, a displacement agent is provided, wherein the raw materials for preparing the displacement agent include any of the above-mentioned cross-linking systems, polyacrylamide and water;

[0024] The mass percentage of the first cross-linking agent in the control and displacement agent is 0.1%-0.6%, the mass percentage of the second cross-linking agent in the control and displacement agent is 0.02%-0.5%, and the mass percentage of the reinforcing agent in the control and displacement agent is 0.0-0.5%;

[0025] The mass percentage of the polyacrylamide in the displacement agent is 0.2%-0.45%.

[0026] In some possible implementations, the operating temperature of the displacement agent is 80°C-130°C.

[0027] The beneficial effects of the technical solution provided by the embodiment of the present invention include at least:

[0028] The cross-linking system provided by the embodiment of the present invention includes a first cross-linking agent and a second cross-linking agent. For the first cross-linking agent, under the premise of at least one of methanol, ethanol, and isopropanol as a promoter, bisphenol A is used instead of phenol to react with formaldehyde. On the one hand, low-toxic bisphenol A improves the safety and environmental protection in synthesis and application. On the other hand, bisphenol A has more active sites, so that the molecular structure of the hydroxymethylated phenolic prepolymer generated by its reaction with formaldehyde contains more hydroxymethyl. The above factors are conducive to reducing the mesh size of the gel-adjusting agent formed by the first cross-linking agent and polyacrylamide, and the branched structure distributed between the meshes is also increased accordingly, so that the gel-adjusting agent forms a more compact three-dimensional network architecture. This compact three-dimensional network architecture can more firmly bind the free water in the gel-adjusting agent, so that the gel-adjusting agent can still maintain good thermal stability even under high temperature conditions (e.g., 130°C), which helps to improve the temperature resistance of the gel system. The second crosslinking agent includes a gel promoter and a deoxidizer. The gel promoter can promote the formation of a three-dimensional network crosslinking structure between polyacrylamide and the first crosslinking agent, and the deoxidizer can reduce the influence of oxygen on the gelling process at high temperature. The gel promoter and the deoxidizer cooperate to promote the formation of a three-dimensional network crosslinking structure in the displacement agent. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0030] On the one hand, an embodiment of the present invention provides a cross-linking system, which includes a first cross-linking agent and a second cross-linking agent; the first cross-linking agent is prepared by the following method: in the presence of an accelerator and an alkaline catalyst, bisphenol A and formaldehyde are reacted to prepare a hydroxymethylated phenolic prepolymer; the hydroxymethylated phenolic prepolymer and a stabilizer are uniformly mixed to prepare the first cross-linking agent. The accelerator is selected from at least one of methanol, ethanol, and isopropanol; the second cross-linking agent includes a gel promoter and a deoxidizer.

[0031] The cross-linking system provided by the embodiment of the present invention includes a first cross-linking agent and a second cross-linking agent. For the first cross-linking agent, under the premise of at least one of methanol, ethanol, and isopropanol as a promoter, bisphenol A is used instead of phenol to react with formaldehyde. On the one hand, low-toxic bisphenol A improves the safety and environmental protection in synthesis and application. On the other hand, bisphenol A has more active sites, so that the molecular structure of the hydroxymethylated phenolic prepolymer generated by its reaction with formaldehyde contains more hydroxymethyl. The above factors are conducive to reducing the mesh size of the gel-adjusting agent formed by the first cross-linking agent and polyacrylamide, and the branched structure distributed between the meshes is also increased accordingly, so that the gel-adjusting agent forms a more compact three-dimensional network architecture. This compact three-dimensional network architecture can more firmly bind the free water in the gel-adjusting agent, so that the gel-adjusting agent can still maintain good thermal stability even under high temperature conditions (e.g., 130°C), which helps to improve the temperature resistance of the gel system. The second crosslinking agent includes a gel promoter and a deoxidizer. The gel promoter can promote the formation of a three-dimensional network crosslinking structure between polyacrylamide and the first crosslinking agent, and the deoxidizer can reduce the influence of oxygen on the gelling process at high temperature. The gel promoter and the deoxidizer cooperate to promote the formation of a three-dimensional network crosslinking structure in the displacement agent.

[0032] In some examples, bisphenol A and formaldehyde are reacted in the presence of a promoter and a catalyst to prepare a hydroxymethylated phenolic prepolymer, which includes the following steps.

[0033] At 40°C-55°C and under stirring conditions, bisphenol A, the accelerator and the first part of the alkaline catalyst are mixed evenly, the raw material system is heated to 60°C-75°C, and the first part of the formaldehyde solution is added dropwise to the raw material system. After the first part of the formaldehyde solution is added dropwise, the second part of the alkaline catalyst is added dropwise until the mixture is evenly mixed, and then the second part of the formaldehyde solution is added dropwise, and then the mixture is reacted at a constant temperature to prepare a hydroxymethylated phenolic prepolymer.

[0034] The hydroxymethylated phenolic prepolymer is prepared by a two-step alkali catalysis process, wherein a first alkali catalysis is carried out at 40°C-55°C to achieve hydroxylation, and a second alkali catalysis is carried out at 60°C-75°C to achieve polycondensation, thereby achieving the smooth formation of a three-dimensional network cross-linked structure in the hydroxymethylated phenolic prepolymer. In addition, by optimizing the two-step alkali catalysis synthesis process, the temperature rise is simplified from 4 times to 2 times, so that the synthesis process of the hydroxymethylated phenolic prepolymer is simple and easy to realize industrial production.

[0035] For example, the temperature corresponding to the primary base catalysis includes, but is not limited to, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, etc. The temperature corresponding to the secondary base catalysis includes, but is not limited to, 60°C, 61°C, 62°C, 63°C, 64°C, 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, etc.

[0036] In some examples, the volume concentration of the formaldehyde solution involved in the embodiments of the present invention is 36%-40%, for example, this includes but is not limited to 36%, 37%, 38%, 39%, 40%, etc.

[0037] In some examples, the mass of the alkaline catalyst in the first part accounts for 65%-80% of the total amount of the alkaline catalyst, including but not limited to 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, etc. The alkaline catalyst in the second part is the balance, that is, the mass of the alkaline catalyst in the second part accounts for 20%-35% of the total amount of the alkaline catalyst.

[0038] The mass of the first part of the formaldehyde solution is 65%-80% of the total amount of the formaldehyde solution (ie, the total mass), and the dropwise addition is completed within 8min-13min; the second part of the formaldehyde solution is the remainder, and the dropwise addition is completed within 8min-13min.

[0039] The dosage of the first part of the formaldehyde solution includes but is not limited to 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, etc. The dosage of the second part of the formaldehyde solution is 20%-35% of the total amount of the formaldehyde solution.

[0040] By controlling the feeding amount and feeding speed of the two parts of formaldehyde solution, the polymerization degree of the hydroxymethylated phenolic prepolymer can be more easily controlled, so that the polymerization degree of the hydroxymethylated phenolic prepolymer is controlled at a lower stage, its water solubility is improved, and it is also conducive to industrial scale-up production.

[0041] In some examples, the alkaline catalyst is a mixture of sodium hydroxide and barium hydroxide, and the molar ratio of sodium hydroxide to barium hydroxide is 2-3:1, which includes but is not limited to 2:1, 2.5:1, 2.8:1, 3:1, etc., so as to achieve a better alkaline catalytic effect.

[0042] In some examples, the stabilizer is selected from at least one of o-aminobenzoic acid and p-aminobenzoic acid; the weight ratio of the hydroxymethylated phenolic prepolymer to the stabilizer is 90:3-7. By defining the stabilizer as above, the self-condensation reaction of the hydroxymethylated phenolic prepolymer can be slowed down, and its life and shelf life can be extended.

[0043] In some examples, the molar ratio of the gel promoter to the oxygen scavenger is 1-5:1. Within this ratio range, the gel promoter and the oxygen scavenger have a better synergistic effect.

[0044] For example, some suitable gel promoters are selected from ammonium chloride to provide a desired acidic environment, and some suitable oxygen scavengers are selected from at least one of thiourea, ammonium thiosulfate, and sodium bisulfite.

[0045] For the first cross-linking agent and the second cross-linking agent prepared by the above method, after testing, the first cross-linking agent (liquid) and the second cross-linking agent (solid) are both easily soluble in water, have little irritating odor, are safe and convenient to use on site, have a storage period of 0.5 to 1 year, are conducive to on-site storage and application, and the cost of the agent is comparable to that of the existing system.

[0046] In some examples, the cross-linking system provided by the embodiments of the present invention further includes a reinforcing agent, and the reinforcing agent is selected from at least one of nano-silicon dioxide, nano-titanium dioxide, and nano-calcium carbonate.

[0047] When the reservoir temperature is higher than 100°C, a reinforcing agent can be used. The reinforcing agent is in the form of particles, and the particles are attached to the skeleton of the gel displacement agent. It can enhance the strength of the gel displacement agent, so that the gel displacement agent still maintains a high strength at high temperatures, and it is also beneficial to extend the temperature resistance time of the gel, thereby significantly enhancing the temperature resistance and salt resistance of the displacement agent.

[0048] On the other hand, an embodiment of the present invention further provides a displacement agent, the raw materials for preparing the displacement agent include any of the above-mentioned cross-linking systems, polyacrylamide and water; wherein the mass percentage of the first cross-linking agent in the displacement agent is 0.1%-0.6%, the mass percentage of the second cross-linking agent in the displacement agent is 0.02%-0.5%, the mass percentage of the reinforcing agent in the displacement agent is 0.0-0.5%; the mass percentage of polyacrylamide in the displacement agent is 0.2%-0.45%.

[0049] The displacement agent provided by the embodiment of the present invention has all the advantages of the cross-linked system provided by the embodiment of the present invention. The above components in the displacement agent act synergistically within the above ratio range, and have at least the following beneficial effects, making it suitable for the displacement operation of high-temperature reservoirs.

[0050] First, the cross-linking system and polyacrylamide can react to form a gel-like displacement agent. Under the conditions of 80°C to 130°C and the total mineralization of the reinjection water being ≤80,000 mg / L, the gelling time of the gel-like displacement agent is 20h-96h, the gelling time is adjustable, and the deep injection capability is good.

[0051] Secondly, the gelling strength of the gel-like displacement agent is 1000-4000 mPa·s, the gelling strength is adjustable, and the gelling agent can be stable for 60 days to 90 days after gelling, and the 90-day viscosity retention rate can reach more than 80%, which has good long-term stability.

[0052] Among them, it is mentioned above that the working temperature of the driving agent provided in the embodiment of the present invention is 80℃-130℃, which includes but is not limited to 80℃, 90℃, 100℃, 110℃, 120℃, 130℃, etc.

[0053] In another aspect, the present invention also provides an application of any of the above-mentioned displacement control agents in displacement control operations. The application includes but is not limited to the following.

[0054] Under stirring conditions, polyacrylamide is added into water until the polyacrylamide is completely and fully dissolved and expanded to prepare a polyacrylamide solution.

[0055] The polyacrylamide solution and the second cross-linking agent are mixed evenly to obtain a first intermediate mixed system.

[0056] A first cross-linking agent and an optional reinforcing agent are added to the first intermediate mixed system and mixed evenly to obtain a second intermediate mixed system, and the second intermediate mixed system is injected into the formation.

[0057] The second intermediate mixed system undergoes a gelling reaction at the formation temperature, for example, the formation temperature is 80° C.-130° C., thereby forming a gel-like displacement agent in the formation.

[0058] In the embodiments of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless otherwise clearly defined.

[0059] The specific embodiments of the present invention will be described in more detail below. Although the specific embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. The specific techniques or conditions not specified in the embodiments are carried out according to the techniques or conditions described in the documents in this area or according to the product specification. The reagents used or the instruments not specified by the manufacturer are all conventional products that can be obtained commercially.

[0060] The polyacrylamide involved in the following examples was purchased from Aisen (China) Flocculant Co., Ltd., with a molecular weight of ≥25 million. The experimental water was oil field on-site injection water with a mineralization of 15000 mg / L-80000 mg / L, and the experimental temperature was 80° C.-130° C. The volume concentration of the formaldehyde solution was 37%.

[0061] Example 1

[0062] 1. Preparation of cross-linking system for control and flooding

[0063] (1) Add an accelerator to a 250 ml three-necked flask equipped with a thermometer, a condenser and a stirrer. The mass of the accelerator is 1% of the mass of bisphenol A. Heat the temperature to 50°C in a constant temperature water bath, start stirring, and then add 1 part (molar ratio) of bisphenol A to the three-necked flask. After dissolving and mixing evenly, keep the temperature at 50°C, and then slowly add a catalyst solution accounting for 75% of the total mass of the catalyst to the three-necked flask and mix evenly. The catalyst solution is a solution of sodium hydroxide and barium hydroxide (molar ratio 2:1), the total mass percentage of sodium hydroxide and barium hydroxide is 5%, and the mass of the catalyst is 3% of the mass of bisphenol A. After heating the reaction system to 70°C, slowly add a formaldehyde solution accounting for 75% of the total mass of the formaldehyde solution to the three-necked flask. The addition is completed within 10 minutes. The molar ratio of bisphenol A to formaldehyde (total) is 1:2.

[0064] (2) Maintaining a constant temperature of 70° C., add the remaining catalyst solution accounting for 25% of the total mass of the catalyst into the three-necked flask, mix well, and then dropwise add the remaining formaldehyde solution accounting for 25% of the total mass of the formaldehyde solution. After the dropwise addition is completed within 10 minutes, a phenolic prepolymer is obtained.

[0065] (3) Add a stabilizer to the three-necked flask, wherein the phenolic prepolymer and the stabilizer are 90 parts by weight and 3 parts by weight, respectively. Mix well and cool to obtain a first crosslinking agent, referred to as crosslinking agent A. 1 .

[0066] The second cross-linking agent, called cross-linking agent B, is prepared by uniformly mixing ammonium chloride and thiourea in a molar ratio of 4:1.

[0067] 2. Preparation of gel-like control agent

[0068] The raw materials for preparing the gel-like displacement agent include: the cross-linking system of Example 1, polyacrylamide and water; wherein the mass percentage of the first cross-linking agent in the displacement agent is 0.25%, the mass percentage of the second cross-linking agent in the displacement agent is 0.02%, and the mass percentage of the polyacrylamide in the displacement agent is 0.3%.

[0069] The gel-like displacement control agent is prepared by the following method:

[0070] (1) According to the mass percentage of the first cross-linking agent, the second cross-linking agent and the polyacrylamide, the corresponding amounts of the respective substances are weighed and the following preparation process is carried out.

[0071] (2) While stirring, slowly add polyacrylamide into on-site water with a mineralization degree of 80,000 mg / L until the polyacrylamide is completely dissolved and expanded to prepare a polyacrylamide solution.

[0072] (3) Then, the crosslinking agent B is added to the polyacrylamide solution and mixed evenly to obtain a first intermediate mixed system.

[0073] (4) Under continuous stirring, slowly add the prepared crosslinking agent A to the first intermediate mixing system. 1 , mix thoroughly and evenly to obtain a second intermediate mixed system.

[0074] (5) The second intermediate mixed system was placed in a thermostatic box at 80° C. for 5 days to allow it to fully react and obtain a light yellow gel-like displacement agent.

[0075] Example 2

[0076] 1. Preparation of cross-linking system for control and flooding

[0077] (1) Add an accelerator to a 250ml three-necked flask equipped with a thermometer, a condenser and a stirrer. The mass of the accelerator is 5% of the mass of bisphenol A. Heat the temperature to 45°C in a constant temperature water bath, start stirring, and then add 1 part (molar ratio) of bisphenol A to the three-necked flask. After dissolving and mixing evenly, keep the temperature at 45°C, and then slowly add a catalyst solution accounting for 75% of the total mass of the catalyst to the three-necked flask and mix evenly. Among them, the catalyst solution is a solution of sodium hydroxide and barium hydroxide (molar ratio 2:1), the total mass percentage of sodium hydroxide and barium hydroxide is 6%, and the mass of the catalyst is 6% of the mass of bisphenol A. After heating the reaction system to 65°C, slowly add a formaldehyde solution accounting for 75% of the total mass of the formaldehyde solution to the above three-necked flask. The addition is completed within 10 minutes. The molar ratio of bisphenol A to formaldehyde (total) is 1:2.5.

[0078] (2) Maintaining a constant temperature of 65° C., add the remaining catalyst solution accounting for 25% of the total mass of the catalyst to the above three-necked flask, mix evenly, and then dropwise add the remaining formaldehyde solution accounting for 25% of the total mass of the formaldehyde solution. The dropwise addition should be completed within 10 minutes. After reacting at 65° C. for 30 minutes, a phenolic prepolymer is obtained.

[0079] (3) Add stabilizer to the above three-necked flask. The weight ratio of phenolic prepolymer and stabilizer is 90 parts and 5 parts respectively. Mix well and cool. Then, the first crosslinking agent is obtained, which is called crosslinking agent A. 2 .

[0080] The second cross-linking agent, called cross-linking agent B, is prepared by uniformly mixing ammonium chloride and thiourea in a molar ratio of 3:1 to obtain cross-linking agent B.

[0081] A reinforcing agent is provided, which is nano-silicon dioxide.

[0082] 2. Preparation of gel-like control agent

[0083] The raw materials for preparing the gel-like displacement agent include: the cross-linking system of Example 2, polyacrylamide and water; wherein the mass percentage of the first cross-linking agent in the displacement agent is 0.1%, the mass percentage of the second cross-linking agent in the displacement agent is 0.1%, the mass percentage of the reinforcing agent in the displacement agent is 0.1%; and the mass percentage of the polyacrylamide in the displacement agent is 0.2%.

[0084] The gel-like displacement control agent is prepared by the following method:

[0085] (1) According to the mass percentage of the first cross-linking agent, the second cross-linking agent and the polyacrylamide, the corresponding amounts of the respective substances are weighed and the following preparation process is carried out.

[0086] (2) While stirring, slowly add polyacrylamide into the on-site water with a mineralization degree of 18000 mg / L until the polyacrylamide is completely dissolved and expanded to prepare a polyacrylamide solution.

[0087] (3) Then, the crosslinking agent B is added to the polyacrylamide solution and mixed evenly to obtain a first intermediate mixed system.

[0088] (4) Under continuous stirring, slowly add the prepared crosslinking agent A to the first intermediate mixing system in sequence. 2 and the reinforcing agent, and are thoroughly mixed to obtain a second intermediate mixed system.

[0089] (5) The second intermediate mixed system was placed in a constant temperature box at 100° C. for 5 days to allow it to fully react and obtain a light yellow gel-like displacement agent.

[0090] Example 3

[0091] 1. Preparation of cross-linking system for control and flooding

[0092] (1) Add an accelerator to a 250 ml three-necked flask equipped with a thermometer, a condenser and a stirrer. The mass of the accelerator is 6% of the mass of bisphenol A. Heat the temperature to 45°C in a constant temperature water bath, start stirring, and then add 1 part (molar ratio) of bisphenol A to the three-necked flask. After dissolving and mixing evenly, keep the temperature at 45°C, and then slowly add a catalyst solution accounting for 75% of the total mass of the catalyst to the three-necked flask and mix evenly. Among them, the catalyst solution is a solution of sodium hydroxide and barium hydroxide (molar ratio 2:1), the total mass percentage of sodium hydroxide and barium hydroxide is 6%, and the mass of the catalyst is 7% of the mass of bisphenol A. After heating the reaction system to 65°C, slowly add a formaldehyde solution accounting for 75% of the total mass of the formaldehyde solution to the above three-necked flask. The addition is completed within 10 minutes. The molar ratio of bisphenol A to formaldehyde (total) is 1:3.

[0093] (2) Maintaining a constant temperature of 65° C., add the remaining catalyst solution accounting for 25% of the total mass of the catalyst to the above three-necked flask, mix evenly, and then dropwise add the remaining formaldehyde solution accounting for 25% of the total mass of the formaldehyde solution. The addition should be completed within 10 minutes. After reacting at 65° C. for 20 minutes, a phenolic prepolymer is obtained.

[0094] (3) Add stabilizer to the above three-necked flask. The weight ratio of phenolic prepolymer and stabilizer is 90 parts and 6 parts respectively. Mix well and cool to obtain crosslinking agent A. 3 .

[0095] The second cross-linking agent, referred to as cross-linking agent B, is prepared by uniformly mixing ammonium chloride and thiourea in a molar ratio of 1:1 to obtain cross-linking agent B.

[0096] A reinforcing agent is provided, which is a mixture of nano silicon dioxide and nano titanium dioxide in a mass ratio of 1:1.

[0097] 2. Preparation of gel-like control agent

[0098] The raw materials for preparing the gel-like displacement agent include: the cross-linking system of Example 3, polyacrylamide and water; wherein the mass percentage of the first cross-linking agent in the displacement agent is 0.3%, the mass percentage of the second cross-linking agent in the displacement agent is 0.3%, the mass percentage of the reinforcing agent in the displacement agent is 0.25%; and the mass percentage of the polyacrylamide in the displacement agent is 0.3%.

[0099] The gel-like displacement control agent is prepared by the following method:

[0100] (1) According to the mass percentage of the first cross-linking agent, the second cross-linking agent and the polyacrylamide, the corresponding amounts of the respective substances are weighed and the following preparation process is carried out.

[0101] (2) While stirring, slowly add polyacrylamide into the on-site water with a mineralization degree of 35,000 mg / L until the polyacrylamide is completely dissolved and expanded to prepare a polyacrylamide solution.

[0102] (3) Then, the crosslinking agent B is added to the polyacrylamide solution and mixed evenly to obtain a first intermediate mixed system.

[0103] (4) Under continuous stirring, slowly add the prepared crosslinking agent A to the first intermediate mixing system in sequence. 3 and the reinforcing agent, and are thoroughly mixed to obtain a second intermediate mixed system.

[0104] (5) The second intermediate mixed system was placed in a constant temperature box at 115° C. for 5 days to allow it to fully react and obtain a light yellow gel-like displacement agent.

[0105] Example 4

[0106] 1. Preparation of cross-linking system for control and flooding

[0107] (1) Add an accelerator to a 250 ml three-necked flask equipped with a thermometer, a condenser and a stirrer. The mass of the accelerator is 8% of the mass of bisphenol A. Heat the temperature to 40°C in a constant temperature water bath, start stirring, and then add 1 part (molar ratio) of bisphenol A to the three-necked flask. After dissolving and mixing evenly, keep the temperature at 40°C. Then slowly add a catalyst solution accounting for 75% of the total mass of the catalyst to the three-necked flask, and then slowly add a catalyst solution accounting for 75% of the total mass of the catalyst to the three-necked flask and mix evenly. Among them, the catalyst solution is a solution of sodium hydroxide and barium hydroxide (molar ratio 2:1), the total mass percentage of sodium hydroxide and barium hydroxide is 7%, and the mass of the catalyst is 8% of the mass of bisphenol A. After heating the reaction system to 60°C, slowly add a formaldehyde solution accounting for 75% of the total mass of the formaldehyde solution to the above three-necked flask. The addition is completed within 10 minutes. The molar ratio of bisphenol A to formaldehyde (total) is 1:3.

[0108] (2) Maintaining a constant temperature of 60° C., add the remaining catalyst solution accounting for 25% of the total mass of the catalyst to the above three-necked flask, mix well and cool, then dropwise add the remaining formaldehyde solution accounting for 25% of the total mass of the formaldehyde solution, and complete the dropwise addition within 10 minutes. After reacting at 65° C. for 60 minutes, a phenolic prepolymer is obtained.

[0109] (3) Add stabilizer to the above three-necked flask. The phenolic prepolymer and stabilizer are 90 parts by weight and 7 parts by weight respectively. After mixing evenly, crosslinking agent A is obtained. 4 .

[0110] The second cross-linking agent, called cross-linking agent B, is prepared by uniformly mixing ammonium chloride and thiourea in a molar ratio of 2:1.

[0111] A reinforcing agent is provided, which is nano titanium dioxide.

[0112] 2. Preparation of gel-like control agent

[0113] The raw materials for preparing the gel-like displacement agent include: the cross-linking system of Example 4, polyacrylamide and water; wherein the mass percentage of the first cross-linking agent in the displacement agent is 0.6%, the mass percentage of the second cross-linking agent in the displacement agent is 0.5%, the mass percentage of the reinforcing agent in the displacement agent is 0.5%; and the mass percentage of the polyacrylamide in the displacement agent is 0.45%.

[0114] The gel-like displacement control agent is prepared by the following method:

[0115] (1) According to the mass percentage of the first cross-linking agent, the second cross-linking agent and the polyacrylamide, the corresponding amounts of the respective substances are weighed and the following preparation process is carried out.

[0116] (2) While stirring, slowly add polyacrylamide into the on-site water with a mineralization degree of 15000 mg / L until the polyacrylamide is completely dissolved and expanded to prepare a polyacrylamide solution.

[0117] (3) Then, the crosslinking agent B is added to the polyacrylamide solution and mixed evenly to obtain a first intermediate mixed system.

[0118] (4) Under continuous stirring, slowly add the prepared crosslinking agent A to the first intermediate mixing system in sequence. 4 and the reinforcing agent, and are thoroughly mixed to obtain a second intermediate mixed system.

[0119] (5) The second intermediate mixed system was placed in a constant temperature box at 130° C. for 5 days to allow it to fully react and obtain a light yellow gel-like displacement agent.

[0120] Test Case

[0121] This test example tests the performance of the cross-linking system provided in Example 1 to Example 4 and its corresponding gel-like displacement agent. For specific parameters, please refer to Table 1.

[0122] Table 1

[0123]

[0124] Note: The shear rate for testing gel strength in Table 1 is 7.34s -1 .

[0125] It can be seen from the data in Table 1 that the cross-linked systems synthesized in Examples 1 to 4 (corresponding to Test Examples 1 to 4, respectively) can react with polyacrylamide to form a stable gel system at high temperature and high salinity, and the viscosity retention rate of the corresponding gel system is above 80%. However, in Test Example 5, since the second cross-linking agent and the reinforcing agent are not added, the gel system prepared by the test example 5 precipitates water and breaks the gel too quickly, and the gelling effect of the gel system corresponding to Test Example 4 (corresponding to the scheme of Example 4) is significantly reduced, because under the same temperature and salinity reaction conditions, the second cross-linking agent and the reinforcing agent are not added, and the temperature and salt resistance of the gel system cannot be effectively improved.

[0126] The above description is only for the purpose of facilitating those skilled in the art to understand the technical solution of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A cross-linking system, characterized in that: The cross-linking system includes a first cross-linking agent and a second cross-linking agent; The first crosslinking agent is prepared by the following method: in the presence of a promoter and an alkaline catalyst, bisphenol A and formaldehyde are reacted to prepare a hydroxymethylated phenolic prepolymer; the hydroxymethylated phenolic prepolymer and a stabilizer are uniformly mixed to prepare the first crosslinking agent; Wherein, the accelerator is selected from at least one of methanol, ethanol and isopropanol; The second cross-linking agent includes a gel promoter and an oxygen scavenger.

2. The cross-linking system according to claim 1, characterized in that The method comprises reacting bisphenol A and formaldehyde in the presence of a promoter and a catalyst to prepare a hydroxymethylated phenolic prepolymer, comprising: At 40° C.-55° C. and under stirring conditions, the bisphenol A, the accelerator and the first part of the alkaline catalyst are uniformly mixed, the raw material system is heated to 60° C.-75° C., and the first part of the formaldehyde solution is added dropwise to the raw material system; After the first part of the formaldehyde solution is added dropwise, the second part of the alkaline catalyst is added dropwise until the mixture is evenly mixed, and then the second part of the formaldehyde solution is added dropwise, followed by constant temperature reaction to prepare the hydroxymethylated phenolic prepolymer.

3. The cross-linking system according to claim 2, characterized in that The mass of the first part of the alkaline catalyst accounts for 65%-80% of the total amount of the alkaline catalyst, and the second part of the alkaline catalyst is the balance; The mass of the first part of the formaldehyde solution is 65%-80% of the total amount of the formaldehyde solution, and the dropwise addition is completed within 8min-13min; the second part of the formaldehyde solution is the remainder, and the dropwise addition is completed within 8min-13min.

4. The cross-linking system according to claim 1, characterized in that The alkaline catalyst is a mixture of sodium hydroxide and barium hydroxide, and the molar ratio of the sodium hydroxide to the barium hydroxide is 2-3:

1.

5. The cross-linking system according to claim 1, characterized in that The stabilizer is selected from at least one of anthranilic acid and p-aminobenzoic acid; The weight ratio of the hydroxymethylated phenolic prepolymer to the stabilizer is 90:3-7.

6. The cross-linking system according to claim 1, characterized in that The molar ratio of the gel promoter to the deoxidizer is 1-5:

1.

7. The cross-linking system according to claim 6, characterized in that The gel promoter is selected from ammonium chloride; The deoxidizer is selected from at least one of thiourea, ammonium thiosulfate and sodium bisulfite.

8. The cross-linking system according to any one of claims 1 to 7, characterized in that: The cross-linking system further comprises a reinforcing agent, and the reinforcing agent is selected from at least one of nano silicon dioxide, nano titanium dioxide and nano calcium carbonate.

9. A displacement agent, characterized in that: The raw materials for preparing the displacement agent include the cross-linking system according to any one of claims 1 to 8, polyacrylamide and water; The mass percentage of the first cross-linking agent in the control and displacement agent is 0.1%-0.6%, the mass percentage of the second cross-linking agent in the control and displacement agent is 0.02%-0.5%, and the mass percentage of the reinforcing agent in the control and displacement agent is 0.0-0.5%; The mass percentage of the polyacrylamide in the displacement agent is 0.2%-0.45%.

10. The control agent according to claim 9, characterized in that: The working temperature of the control and displacement agent is 80°C-130°C.

Images