Adsorptive retarder, self-generating acid plugging-removing fluid with retardation and preparation method thereof

Abstract

The application relates to an adsorptive retarder, a self-generating acid plugging removal fluid and a preparation method thereof, and belongs to the technical field of oil and gas development. The preparation method of the adsorptive retarder comprises the following steps: S1. n parts of polyethylene imine are dissolved in a solvent, and then 2x parts of bromoethane are added dropwise for reaction; S2. triethylamine is added and stirred uniformly, and then y parts of diethyl phosphinite are added dropwise for reaction; S3. the reaction product prepared in the step S2 is distilled under reduced pressure, hydrolyzed, and then precipitated, washed and dried. According to the mass percentage, the self-generating acid plugging removal fluid comprises 0.3%-2.0% of the adsorptive retarder, 15%-40% of a live acid agent, 5%-15% of a fluorine source, 0.8%-3.0% of a corrosion inhibitor, 0.5%-2.5% of an iron ion stabilizer and 0.5%-1.0% of a cleanup agent, and the rest is water. The plugging removal fluid can not only inhibit corrosion of the pipe column at high temperature, but also control the acid-rock reaction rate, maximally protect the rock matrix, avoid waste of the acid liquid, force the acid liquid to penetrate into the deep stratum and realize efficient and accurate removal of the plugging material.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas development technology, specifically relating to an adsorption-type retarder, a retarder-type self-generating acid unblocking solution, and their preparation methods. Background Technology

[0002] In oil and gas field development, formation damage in the near-wellbore zone is a major cause of declining oil and gas well production. Acidizing, as a core technology for restoring and enhancing oil and gas well productivity, directly depends on the performance of the acid system.

[0003] While traditional acids (such as hydrochloric acid and terrine) are effective, they have inherent problems such as rapid reaction, short action distance, strong corrosiveness, and susceptibility to secondary precipitation. Furthermore, wellbore scaling and cuttings accumulation can significantly impact oil and gas well production, drastically reduce oil pressure, and even cause well shutdowns. Although traditional acids are effective at unclogging, they severely corrode tubing in high-temperature wells, easily causing perforation, especially in older wells where reduced tubing strength makes them prone to breakage and other production accidents.

[0004] To address these issues, the industry has developed autogenous acid generation technology, which gradually releases hydrogen ions through wellbore or formation temperatures, thus slowing down the acid flow and inhibiting corrosion. For example, hydrochloric acid is generated by the reaction of ammonium chloride and formaldehyde at high temperatures downhole, which slows down the release rate of hydrogen ions, increases the acid's contact distance, and, because the surface is not acidic, the release of hydrogen ions at high wellbore and formation temperatures avoids the severe corrosion of the tubing caused by the acid at high temperatures.

[0005] However, existing autogenous acid generation technologies still have shortcomings: First, there is a lack of effective retardation methods, and the retarders used are generally ineffective. Second, the retardation mechanism is singular, mainly relying on temperature to control the reaction rate. For heterogeneous strata, the acid may still overreact in high-permeability areas, making it difficult to effectively acidify low-permeability damaged areas. Third, there is a lack of protection for the rock matrix. Even with retarded acid, once it comes into contact with the rock surface, it reacts and is consumed rapidly, resulting in a large amount of acid being wasted on dissolving the rock matrix rather than specifically treating the blockage, thus limiting the penetration depth of the acid. Furthermore, it cannot cope with complex blockages; a single autogenous hydrochloric acid system has limited effectiveness against blockages caused by siliceous minerals (clay, quartz). Summary of the Invention

[0006] Therefore, the purpose of this application is to provide an adsorption-type retarder, a retarded autogenous acid unblocking solution, and a method for preparing the same, to solve the problems in existing autogenous acid systems, such as the lack of effective retarding methods, inaccurate control of acid reaction rate, insufficient penetration depth, inadequate protection of the rock matrix, and severe corrosion of the tubing by acid at high temperatures. This solution can both inhibit corrosion of the tubing at high temperatures and control the acid-rock reaction rate, maximizing the protection of the rock matrix and avoiding acid waste, forcing the acid to penetrate deep into the formation, and achieving efficient and precise removal of blockages.

[0007] The embodiments of this application are implemented as follows:

[0008] This application provides an adsorption-type retarder, the preparation method of which includes the following steps:

[0009] S1. Based on the amount of substance, dissolve n parts of polyethyleneimine in a solvent, add 2x parts of bromoethane dropwise, and then carry out a quaternization reaction;

[0010] S2. Add triethylamine and stir until homogeneous, then add y parts of diethylphosphonite dropwise to carry out the phosphonylation reaction;

[0011] S3. The reaction product obtained in step S2 is subjected to vacuum distillation and hydrolysis, then precipitated, washed and dried;

[0012] Where, n:x:y=(1.8~2.2):(0.8~1.2):(0.8~1.2).

[0013] As a preferred embodiment, the reaction temperature in step S1 is 20-30°C and the reaction time is 4-8 hours; the reaction temperature in step S2 is 60-80°C and the reaction time is 6-12 hours.

[0014] As a preferred embodiment, in step S3, concentrated hydrochloric acid is used for hydrolysis, and acetone and / or diethyl ether are used for precipitation and washing.

[0015] As a preferred embodiment, the adsorbent retarder comprises a polymer with the structure shown in formula (1):

[0016] , structure (1).

[0017] This adsorbent retarder integrates two major mechanisms: "temperature-controlled release" and "pH-responsive adsorption," enabling precise and multi-level regulation of acid generation and reaction, and possessing multiple synergistic control mechanisms.

[0018] This application also provides a slow-release self-acid-generating unblocking solution, which, by mass percentage, includes 0.3% to 2.0% of the adsorption-type retarder as described above; and further includes the following components: 15% to 40% acid-generating agent, 5% to 15% fluorine source, 0.8% to 3.0% corrosion inhibitor, 0.5% to 2.5% iron ion stabilizer, 0.5% to 1.0% drainage aid, and the balance being water.

[0019] As a preferred embodiment, the acid-generating agent comprises an ammonium salt and an organic nitrogen compound, wherein the ammonium salt comprises at least one of ammonium chloride and ammonium bromide, and the organic nitrogen compound comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and 2-pyrrolidone.

[0020] As a preferred embodiment, the fluorine source includes at least one of ammonium fluoroborate and ammonium fluorosilicate.

[0021] As a preferred embodiment, the corrosion inhibitor includes at least one of alkynyl alcohol, pyridine, and quinoline.

[0022] As a preferred embodiment, the iron ion stabilizer includes at least one of ethylenediaminetetraacetic acid, nitric acid triacetic acid, and sodium isoascorbate.

[0023] As a preferred embodiment, the drainage aid includes at least one of isooctanol polyoxyethylene ether, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

[0024] The slow-release self-generating acid unblocking solution provided in this application integrates "dual self-generation" and "adsorption slow-release" into one. It achieves precise control of acid generation and reaction through a triple control mechanism (temperature, pH, and adsorption), thereby achieving the effect of not corroding the tubing and efficiently unblocking deep into the formation.

[0025] This application also provides a method for preparing a slow-release self-generating acid unblocking solution, including the following steps:

[0026] S1. Add the adsorbent retarder to water and stir until well mixed to obtain liquid 1;

[0027] S2. Add corrosion inhibitor, iron ion stabilizer, acid generator and fluorine source to liquid 1, stir and mix evenly to obtain liquid 2;

[0028] S3. Add the drainage aid to liquid 2 and stir to form a homogeneous solution.

[0029] This method is simple in process, has low requirements for environment and equipment, is suitable for industrial application, and has high market value.

[0030] Compared with existing technologies, the beneficial effects of the adsorption-type retarder and the retarder-type self-generating acid unblocking solution provided in this application are as follows:

[0031] 1. Deep penetration capability: The "molecular protective shell" formed by the adsorption-type retarder greatly slows down the acid-rock reaction, allowing the acid to penetrate deep into the strata and effectively act on the blockage area, resulting in a qualitative improvement in the acidizing effect (effective action distance).

[0032] 2. It can selectively unblock and protect the reservoir: the adsorption retarder preferentially adsorbs on the surface of the rock matrix, protecting the reservoir skeleton, while the acid is "driven" to the location of the blockage to react, achieving the effect of "supporting the healthy and eliminating the evil".

[0033] 3. Synergistic effect of the system: The self-generating acid system provided in this application is based on the synergy of acid-generating agent and fluorine source. Hydrochloric acid and hydrofluoric acid are released stepwise and not simultaneously. The dual self-generating acid provides the pH trigger condition for the activation of the adsorption-type retarder, while the adsorption-type retarder provides time and space for the dual self-generating acid to act deeply. The two complement each other and have a synergistic effect.

[0034] 4. The dissolution and dispersion rate is over 80%, and the corrosion rate of N80 carbon steel at 120℃ is less than 9g / (㎡·h), and the acid-rock reaction rate is less than 7g / min. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. The illustrative embodiments and descriptions of this application are for explanation only and are not intended to limit the scope of this application. Any product identical or similar to this application, derived by any person based on the teachings of this application or by combining features of this application with other prior art, falls within the protection scope of this application.

[0036] For any experimental steps or conditions not specified in the examples, the procedures or conditions described in the conventional experimental procedures in the art can be followed. Reagents and other instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0037] This application provides an adsorption-type retarder, specifically a polyethyleneimine-quaternary ammonium salt-phosphonate copolymer, which belongs to the polymer family. Its molecular structural formula is:

[0038]

[0039] In the formula, n:x:y=(1.8~2.2):(0.8~1.2):(0.8~1.2).

[0040] The preparation method of this adsorption-type retarder is as follows:

[0041] S1. Quaternization reaction: Polyethyleneimine (PEI) is dissolved in a solvent, preferably ethanol; then bromoethane is slowly added dropwise at low temperature; the temperature is preferably 0-5°C, and more preferably, it is added dropwise under stirring at 100-300 rpm. Low temperature and stirring can ensure that polyethyleneimine and bromoethane are fully and uniformly mixed, and avoid material decomposition and loss due to heat; then the temperature is raised to obtain a partially quaternized polyethyleneimine solution; the temperature after heating is preferably 20-30°C, and the reaction time is preferably 4-8 hours. In the further reaction, it is preferable to continue stirring at 100-300 rpm to make the reaction more complete and uniform and avoid material loss.

[0042] S2. Phosphonylation reaction: Triethylamine, an acid-binding agent, is added to the solution, followed by slow dropwise addition of diethylphosphonite. The reaction is carried out for 6 to 12 hours to form a copolymer containing phosphonite precursors. The preferred reaction temperature is 60 to 80°C, and the stirring is preferably maintained at 100 to 300 rpm. The preferred reaction time is 6 to 12 hours.

[0043] S3. Hydrolysis and purification: The solvent is removed by vacuum distillation of the reaction product, and then hydrolyzed with concentrated hydrochloric acid to cleave the diethyl protecting group and form a pH-sensitive ester bond structure. Finally, the product is precipitated and washed with acetone and / or diethyl ether, and dried after thorough washing to obtain the adsorption-type retarder.

[0044] That is, the chemical reaction formula for preparing the adsorption-type retarder is:

[0045] .

[0046] By molar amount, n parts of polyethyleneimine react with 2x parts of bromoethane to obtain partially quaternized polyethyleneimine, in which x parts of the amine are quaternized. The product then reacts with y parts of diethylphosphonite to obtain a copolymer containing a phosphonate precursor. The portion of the original polyethyleneimine that did not react with bromoethane (i.e., was not quaternized) undergoes a nucleophilic reaction with diethylphosphonite, introducing diethylphosphonite groups. The remaining amount of amine in the original polyethyleneimine is nxy, meaning the amount of amine that did not react with either bromoethane or diethylphosphonite is nxy. Finally, the product is hydrolyzed to obtain the final adsorption-type retarder.

[0047] As can be seen from the above molecular structure, the main chain skeleton of this adsorption-type retarder is polyethyleneimine (PEI), which is rich in a large number of amine groups (-NH-); in addition, some amine groups are quaternized to form positively charged quaternary ammonium salt groups (—(CH2CH2N)). + (CH2CH3)2·Br - ) x—); another portion of the amine groups are linked to phosphonate groups via pH-sensitive ester bonds. The mechanism of action of this adsorption-type retarder in the unblocking solution provided in this application is as follows:

[0048] First, during the injection phase, the adsorbent retarder enters the formation along with the acid system.

[0049] Then, as a polymer, its molecular chains extend after dissolving in water. After entering the strata, the quaternary ammonium salt groups on the molecular chains are strongly adsorbed onto the surface of negatively charged clay minerals (such as kaolinite and illite) through electrostatic attraction, forming a dense "molecular film". This effectively prevents the rapid contact between the acid and the clay minerals, prevents the clay minerals from dispersing and migrating, and slows down the reaction of the acid on the clay surface.

[0050] Then, as the authigenic acid system takes effect, the generated HCl gradually decreases the local pH value. When the pH value drops to the threshold (pH < 4), the pH-sensitive ester bonds connecting the phosphonate groups hydrolyze, releasing the highly adsorbed phosphonate groups. The released phosphonate groups form stable chemical chelates with calcium and magnesium ions on the surface of carbonate rocks (such as calcite and dolomite), acting like "molecular anchors" to firmly fix the polymer to the carbonate rock surface, forming a dense and robust "protective shell." This protective shell greatly slows down the reaction rate of subsequently generated HCl and HF with the rock matrix, forcing the acid to migrate deeper along the pores and preferentially react with the blockages.

[0051] Finally, the acid in the self-generating acid unblocking solution is transported in large quantities to the blockage-rich area. After a long period of slow reaction, the acid finally exerts its strong dissolving ability, destroying the protective layer provided by the adsorption-type retarder and completely removing the blockage.

[0052] This application also provides a slow-release self-acid-generating unblocking solution, which comprises the following components by mass percentage: 15%–40% acid-generating agent, 5%–15% fluorine source, 0.3%–2.0% adsorption-type retarder, 0.8%–3.0% corrosion inhibitor, 0.5%–2.5% iron ion stabilizer, 0.5%–1.0% drainage aid, and the balance being water.

[0053] The acid-generating agent includes ammonium salts and organic nitrogen compounds, which are used to generate hydrochloric acid in situ under formation or wellbore temperature conditions. The ammonium salts include at least one of ammonium chloride and ammonium bromide, and the organic nitrogen compounds include at least one of N,N-dimethylformamide (hereinafter referred to as DMF), N,N-dimethylacetamide (hereinafter referred to as DMAc), and 2-pyrrolidone.

[0054] The fluorine source includes at least one of ammonium fluoroborate and ammonium fluorosilicate, which is used to react with HCl generated in situ to further produce hydrofluoric acid (HF).

[0055] The adsorption-type retarder is the aforementioned adsorption-type retarder that the applicant developed himself.

[0056] Corrosion inhibitors include at least one of alkynols, pyridines, quinolines and their derivatives, including methylbutynols, 2-methylpyridines, methylquinoline quaternary ammonium salts, etc.

[0057] Iron ion stabilizers include at least one of ethylenediaminetetraacetic acid, nitric acid triacetic acid, and sodium isoascorbate.

[0058] The drainage aid includes at least one of isooctanol polyoxyethylene ether, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

[0059] The slow-release self-generating acid unblocking solution provided in this application is prepared by the following method:

[0060] S1. While maintaining a stirring speed of 100-300 rpm, slowly add the measured amount of adsorption retarder to the water and stir for 30-60 minutes until completely mixed to obtain liquid 1;

[0061] S2. Add the measured amount of corrosion inhibitor, iron ion stabilizer, acid generator, and fluorine source to liquid 1, and continue stirring for 15-30 minutes until completely mixed to obtain liquid 2.

[0062] S3. Add the measured amount of drainage aid to liquid 2 and continue stirring for 15-30 minutes to form a homogeneous solution, thus obtaining the slow-release self-generating acid unblocking solution.

[0063] This method is simple, has low requirements for environment and equipment, is suitable for industrial application, and has high market value. The resulting unblocking fluid can be directly injected into oil and gas wells. Therefore, in actual production, it is recommended to prepare the unblocking fluid on-site using the above method so that it can be used immediately after preparation.

[0064] The following examples will provide a more detailed description of the slow-release autogenous acid unblocking solution provided in this application. Examples 1-3 specifically prepared an adsorption-type retarder, and Examples 4-8 specifically prepared a slow-release autogenous acid unblocking solution.

[0065] Example 1:

[0066] Dissolve 100g of polyethyleneimine in 500ml of ethanol and place at 0℃; slowly add 150g of bromoethane dropwise while stirring at 250rpm; after the addition is complete, raise the temperature to 25℃ and continue stirring for 6 hours.

[0067] Add 50g of triethylamine to the reaction solution, then slowly add 80g of diethylphosphonite, heat to 70℃ and stir for 8 hours;

[0068] Ethanol was removed by vacuum distillation to obtain a viscous liquid. 200 ml of 31% concentrated hydrochloric acid was added, and the mixture was hydrolyzed at 80 °C for 4 hours. The hydrolysate was poured into a large amount of acetone for precipitation, filtration, and washing. The washing process was repeated 3 times to ensure thorough cleaning. The solution was then dried under vacuum at 60 °C for 12 hours to obtain a pale yellow powdery adsorbent retarder.

[0069] Example 2:

[0070] Dissolve 100g of polyethyleneimine in 600ml of ethanol and place at 3℃; slowly add 200g of bromoethane dropwise while stirring at 300rpm; after the addition is complete, raise the temperature to 30℃ and continue stirring for 8 hours.

[0071] Add 80g of triethylamine to the reaction solution, then slowly add 100g of diethylphosphonite, heat to 80℃ and stir for 12 hours;

[0072] Ethanol was removed by vacuum distillation to obtain a viscous liquid. 260 ml of 31% concentrated hydrochloric acid was added, and the mixture was hydrolyzed at 85 °C for 3 hours. The hydrolysate was poured into a large amount of diethyl ether for precipitation, filtration, and washing. The washing process was repeated 3 times to ensure thorough cleaning. The solution was then dried under vacuum at 50 °C for 14 hours to obtain a pale yellow powdery adsorbent retarder.

[0073] Example 3:

[0074] Dissolve 100g of polyethyleneimine in 800ml of ethanol and place at 5℃; slowly add 280g of bromoethane dropwise while stirring at 100rpm; after the addition is complete, raise the temperature to 20℃ and continue stirring for 4 hours.

[0075] Add 90g of triethylamine to the reaction solution, then slowly add 150g of diethylphosphonite, heat to 60℃ and stir for 6 hours;

[0076] Ethanol was removed by vacuum distillation to obtain a viscous liquid. 360 ml of 31% concentrated hydrochloric acid was added, and the mixture was hydrolyzed at 75°C for 6 hours. The hydrolysate was poured into a large amount of acetone for precipitation, filtration, and washing. The washing process was repeated 3 times to ensure thorough cleaning. The solution was then dried under vacuum at 75°C for 10 hours to obtain a pale yellow powdery adsorbent retarder.

[0077] Example 4:

[0078] Raw materials should be used according to weight percentage:

[0079] 25% acid-generating agent, specifically 10% ammonium chloride and 15% DMF;

[0080] 8% of the fluorine source, specifically ammonium fluoroborate;

[0081] 0.8% of an adsorbent retarder was prepared in Example 1;

[0082] 1.5% corrosion inhibitor, specifically propargyl alcohol;

[0083] 1.0% iron ion stabilizer, specifically ethylenediaminetetraacetic acid;

[0084] 0.6% of the drainage aid, specifically isooctanol polyoxyethylene ether;

[0085] The remainder is water.

[0086] The above raw materials are used to prepare the unblocking solution using the following method:

[0087] S1. While stirring at 100 rpm, slowly add the measured amount of adsorbent retarder to the water and stir for 30 minutes until completely mixed to obtain liquid 1;

[0088] S2. Add the measured amount of corrosion inhibitor, iron ion stabilizer, acid generator, and fluorine source to liquid 1, and continue stirring for 15 minutes until completely mixed to obtain liquid 2.

[0089] S3. Add the measured amount of drainage aid to liquid 2 and continue stirring for 15 minutes to form a homogeneous solution, thus obtaining a slow-acting self-generating acid unblocking solution.

[0090] Example 5:

[0091] Raw materials should be used according to weight percentage:

[0092] 30% acid-generating agent, specifically 12% ammonium bromide and 18% 2-pyrrolidone;

[0093] 10% of the fluorine source, specifically ammonium fluorosilicate;

[0094] 1.2% of an adsorbent retarder was prepared in Example 2;

[0095] 2.0% corrosion inhibitor, specifically quinoline;

[0096] 1.5% iron ion stabilizer, specifically triacetic acid;

[0097] 0.5% of the discharge aid, specifically sodium dodecyl sulfate;

[0098] The remainder is water.

[0099] The above raw materials are used to prepare the unblocking solution using the following method:

[0100] S1. While stirring at 200 rpm, slowly add the metered adsorption retarder to the water and stir for 45 minutes until completely mixed to obtain liquid 1;

[0101] S2. Add the measured amount of corrosion inhibitor, iron ion stabilizer, acid generator, and fluorine source to liquid 1, and continue stirring for 22 minutes until completely mixed to obtain liquid 2;

[0102] S3. Add the measured amount of drainage aid to liquid 2 and continue stirring for 22 minutes to form a homogeneous solution, thus obtaining a slow-release self-generating acid unblocking solution.

[0103] Example 6:

[0104] Raw materials should be used according to weight percentage:

[0105] The acid-generating agent is 28%, specifically consisting of 8% ammonium chloride and 20% DMAc.

[0106] The fluorine source is 6%, specifically ammonium fluoroborate;

[0107] 0.5% of an adsorbent retarder was prepared in Example 3;

[0108] 1.0% corrosion inhibitor, specifically pyridine;

[0109] 0.8% iron ion stabilizer, specifically sodium isoascorbate;

[0110] 1.0% of the discharge aid, specifically sodium dodecylbenzenesulfonate;

[0111] The remainder is water.

[0112] The above raw materials are used to prepare the unblocking solution using the following method:

[0113] S1. While stirring at 300 rpm, slowly add the metered adsorption retarder to the water and stir for 60 minutes until completely mixed to obtain liquid 1;

[0114] S2. Add the measured amount of corrosion inhibitor, iron ion stabilizer, acid generator, and fluorine source to liquid 1, and continue stirring for 30 minutes until completely mixed to obtain liquid 2;

[0115] S3. Add the measured amount of drainage aid to liquid 2 and continue stirring for 30 minutes to form a homogeneous solution, thus obtaining a slow-acting self-generating acid unblocking solution.

[0116] Example 7:

[0117] Raw materials should be used according to weight percentage:

[0118] 40% acid-generating agent, specifically 18% ammonium chloride and 22% DMF;

[0119] The 15% fluorine source is specifically 7.5% ammonium fluoroborate and 7.5% ammonium fluorosilicate;

[0120] 2.0% of the adsorption retarder, specifically including 1.0% of the adsorption retarder prepared in Example 1 and 1.0% of the adsorption retarder prepared in Example 3;

[0121] 3.0% corrosion inhibitor, specifically 1.5% quinoline, 0.5% 2-methylpyridine, and 1.0% methylbutynol;

[0122] 2.5% iron ion stabilizer, specifically 1.0% ethylenediaminetetraacetic acid and 1.5% sodium isoascorbate;

[0123] The 0.8% discharge aid specifically consists of 0.4% sodium dodecyl sulfate and 0.4% sodium dodecylbenzene sulfonate;

[0124] The remainder is water.

[0125] The above raw materials are used to prepare the unblocking solution using the following method:

[0126] S1. While stirring at 150 rpm, slowly add the metered adsorption retarder to the water and stir for 40 minutes until completely mixed to obtain liquid 1;

[0127] S2. Add the measured amount of corrosion inhibitor, iron ion stabilizer, acid generator, and fluorine source to liquid 1, and continue stirring for 20 minutes until completely mixed to obtain liquid 2;

[0128] S3. Add the measured amount of drainage aid to liquid 2 and continue stirring for 20 minutes to form a homogeneous solution, thus obtaining a slow-release self-generating acid unblocking solution.

[0129] Example 8:

[0130] Raw materials should be used according to weight percentage:

[0131] 15% acid-generating agent, specifically 7% ammonium chloride and 8% DMF;

[0132] 5% of the fluorine source, specifically ammonium fluoroborate;

[0133] 0.3% of an adsorption-type retarder was prepared in Example 2;

[0134] 0.8% corrosion inhibitor, specifically 1-benzylquinoline chloride;

[0135] 0.5% iron ion stabilizer, specifically ethylenediaminetetraacetic acid;

[0136] 1.0% of the drainage aid, specifically 0.5% isooctanol polyoxyethylene ether and 0.5% sodium dodecylbenzenesulfonate;

[0137] The remainder is water.

[0138] The above raw materials are used to prepare the unblocking solution using the following method:

[0139] S1. While maintaining a stirring speed of 250 rpm, slowly add the metered adsorption retarder to the water, stir for 50 minutes, and mix thoroughly to obtain liquid 1;

[0140] S2. Add the measured amount of corrosion inhibitor, iron ion stabilizer, acid generator, and fluorine source to liquid 1, and continue stirring for 25 minutes until completely mixed to obtain liquid 2.

[0141] S3. Add the measured amount of drainage aid to liquid 2 and continue stirring for 25 minutes to form a homogeneous solution, thus obtaining a slow-acting self-generating acid unblocking solution.

[0142] The performance of the unblocking fluids obtained in Examples 4-8 will be tested below.

[0143] Test index 1, dissolution and dispersion ability:

[0144] Dissolution and dispersion ability is a core indicator for evaluating unblocking agents, reflecting their ability to dissolve and disperse blockages. Before testing, several identical, clean, and dry beakers and four types of blockage samples were prepared. The unblocking solution provided in this application was used to test the dissolution and dispersion ability.

[0145] The blockage samples were: marble (simulating carbonate rock and carbonate scale), silica particles (simulating sandstone), oil-based mud (simulating organic blockage), and on-site blockage (which, after testing, included rock fragments, carbonate scale, iron corrosion products, sludge, etc.).

[0146] The specific testing method is as follows: First, weigh the dry beakers separately and record the mass as m0; then place the blockage in the beaker and weigh it together with the beaker and record the mass as m1; then the mass of the blockage is m1 - m0; then add 80 times the weight of the blockage-removing liquid to the beaker.

[0147] The unblocking ability was tested at different temperatures. Specifically, when the test temperature was ≤95℃, the beaker mouth was sealed with a beaker sealing film, and then placed in an oven for dissolution and dispersion. When the test temperature was >95℃, all the blockage material and unblocking solution in the beaker were poured into a high-temperature aging tank lined with polytetrafluoroethylene, sealed, and then placed in an oven for dissolution and dispersion. All samples were dissolved for 4 hours, that is, the blockage material was dissolved and dispersed in the unblocking solution for 4 hours. Then, the mixture in the beaker or high-temperature aging tank was poured out and filtered through a 20-mesh sieve. The residue in the beaker or aging tank was also rinsed with clean water and filtered through a 20-mesh sieve to obtain all the residue. All the residue was transferred to another dry beaker (this beaker was pre-dried and weighed, and the mass was recorded as m2). Then, the beaker containing the residue was placed open in a drying oven at 25℃ and allowed to dry for 12 hours. The beaker and the residue were weighed together, and the mass was recorded as m3. The mass of the residue after drying is m3 - m2.

[0148] Dissolution and dispersion rate = [(m1-m0)-(m3-m2)] / (m1-m0)×100%. After experimental verification, the dissolution and dispersion rates of the unblocking solutions obtained in Examples 4 to 8 are shown in Table 1.

[0149] Table 1 shows the dissolution and dispersion rates (%) of the unblocking solutions obtained in Examples 4-8 at 70℃:

[0150]

[0151] As can be seen from Table 1, the unblocking solutions prepared in Examples 4 to 8 have good dissolving and dispersing effects on various blockages, with a dissolving and dispersing rate of >80% at 70°C. The unblocking solution provided in Example 7 has the best unblocking effect on various blockages.

[0152] Table 2 shows the dissolution and dispersion rates (%) of the unblocking solutions obtained in Examples 4-8 at 120℃:

[0153]

[0154] As can be seen from Table 2, at a temperature of 120℃, Examples 4 to 8 all have good dissolving and dispersing effects on various blockages, with a dissolving and dispersing rate of >83%, and the unblocking solution provided in Example 7 has the best unblocking effect on various blockages.

[0155] Compared to an environment of 70°C, the unblocking solutions provided in Examples 4 to 8 not only had no negative impact on dissolution and dispersion after the temperature was increased to 120°C, but also had a higher dissolution and dispersion rate for various blockages, which also proves that the unblocking solutions provided in this application have excellent high-temperature resistance.

[0156] Test index 2, corrosion rate:

[0157] The static corrosion rate of N80 carbon steel under normal pressure at different temperatures was tested according to the method specified in SY / T 5886-2018. The corrosion rate is expressed in g / (m²·h), and the test results are shown in Table 3.

[0158] Table 3 shows the corrosion rate data (g / (㎡·h)) of the unblocking fluids obtained in Examples 4–8 at different temperatures:

[0159]

[0160] As can be seen from Table 3, when the temperature is ≤120℃, the corrosion rate of N80 carbon steel in Examples 4 to 8 is less than 9g / (㎡·h), indicating that the unblocking solutions provided in Examples 4 to 8 have a good corrosion control effect.

[0161] Test index 3, acid-rock reaction rate:

[0162] The specific testing method is as follows: First, weigh the dry beakers separately and record the mass as m0; then place the rocks (marble, silica particles) in the beakers and weigh them together with the beakers, and record the mass as m1; then the mass of the rocks is m1 - m0; then add 10 times the weight of the rocks of the unblocking liquid to the beakers.

[0163] Unblocking ability tests were conducted at different temperatures. Specifically, when the test temperature was ≤95℃, the beaker mouth was sealed with a beaker sealing film and then placed in an oven to dissolve. When the test temperature was >95℃, all the blockage material and unblocking solution in the beaker were poured into a high-temperature aging tank lined with polytetrafluoroethylene, sealed, and then placed in an oven to dissolve. All samples were dissolved for 30 minutes, i.e., the rock dissolved in the unblocking solution for 30 minutes. Then, the mixture in the beaker or high-temperature aging tank was poured out and filtered through a 20-mesh sieve. The residue in the beaker or aging tank was also rinsed with clean water and filtered through a 20-mesh sieve to obtain all the residue. All the residue was transferred to another dry beaker (this beaker was pre-dried and weighed, and the mass was recorded as m2). Then, the beaker containing the residue was placed open in a drying oven at 25℃ and allowed to dry for 12 hours. The beaker and the residue were weighed together, and the mass was recorded as m3. The mass of the residue after drying is m3 - m2.

[0164] The acid-rock reaction rate is calculated as [(m1 - m0) - (m3 - m2)] / 30 min, with units of g / min. The results of the acid-rock reaction rates of the unblocking solution, 10% hydrochloric acid, and soil acid (including 12% hydrochloric acid and 3% hydrofluoric acid) obtained in Examples 4 to 8 are shown in Table 4.

[0165] Table 4 shows the acid-rock reaction rate (g / min) of the unblocking solution, 10% hydrochloric acid, and terrine obtained in Examples 4-8 at different temperatures:

[0166]

[0167] As can be seen from Table 4, the acid-rock reaction rate of the unblocking fluids obtained in Examples 4 to 8 at different temperatures was low, all less than 7 g / min; moreover, at 90℃ and 75℃, the acid-rock reaction rate decreased significantly, basically less than 1 g / min, with the highest being 2.19 g / min.

[0168] Under the same temperature conditions, hydrochloric acid and arginine have very high acid-rock reaction rates. Except for hydrochloric acid, which cannot corrode silica particles, the acid-rock reaction rates are all greater than 10 g / min, with the highest reaching 16 g / min.

[0169] The above comparison results show that the unblocking fluid provided in this application has a significant function in slowing down acid-rock reactions, with an excellent slowing effect, which helps to unblock deep formations and expand the unblocking radius.

[0170] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An adsorption-type retarder, the preparation method of which includes the following steps: S1. Based on the amount of substance, dissolve n parts of polyethyleneimine in a solvent, add 2x parts of bromoethane dropwise, and then carry out a quaternization reaction; S2. Add triethylamine and stir until homogeneous, then add y parts of diethylphosphonite dropwise to carry out the phosphonylation reaction; S3. The reaction product obtained in step S2 is subjected to vacuum distillation and hydrolysis, then precipitated, washed and dried; Where, n:x:y=(1.8~2.2):(0.8~1.2):(0.8~1.2).

2. The adsorption-type retarder according to claim 1, characterized in that, In step S1, the reaction temperature is 20–30°C and the reaction time is 4–8 hours; in step S2, the reaction temperature is 60–80°C and the reaction time is 6–12 hours.

3. The adsorption-type retarder according to claim 1, characterized in that, In step S3, concentrated hydrochloric acid is used for hydrolysis, and acetone and / or ether are used for precipitation and washing.

4. The adsorption-type retarder according to claim 1, characterized in that, The adsorption-type retarder comprises a polymer with the structure shown in formula (1): , structure (1).

5. A slow-acting self-generating acid unblocking solution, characterized in that, The product comprises, by mass percentage, 0.3% to 2.0% of the adsorption-type retarder as described in any one of claims 1 to 4; and further comprises the following components: 15% to 40% of acid-generating agent, 5% to 15% of fluorine source, 0.8% to 3.0% of corrosion inhibitor, 0.5% to 2.5% of iron ion stabilizer, 0.5% to 1.0% of drainage aid, with the balance being water.

6. The slow-release self-generating acid unblocking solution according to claim 5, characterized in that, The acid-generating agent includes ammonium salts and organic nitrogen compounds. The ammonium salts include at least one of ammonium chloride and ammonium bromide, and the organic nitrogen compounds include at least one of N,N-dimethylformamide, N,N-dimethylacetamide, and 2-pyrrolidone.

7. The slow-release self-generating acid unblocking solution according to claim 5, characterized in that, The fluorine source includes at least one of ammonium fluoroborate and ammonium fluorosilicate.

8. The slow-release self-generating acid unblocking solution according to claim 5, characterized in that, The corrosion inhibitor includes at least one of alkynol, pyridine, and quinoline.

9. The slow-release self-generating acid unblocking solution according to claim 5, characterized in that, The iron ion stabilizer includes at least one of ethylenediaminetetraacetic acid, nitric acid triacetic acid, and sodium isoascorbate.

10. The slow-release self-generating acid unblocking solution according to claim 5, characterized in that, The drainage aid includes at least one of isooctanol polyoxyethylene ether, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate.

11. A method for preparing a slow-release self-generating acid unblocking solution as described in any one of claims 5 to 10, characterized in that, Includes the following steps: S1. Add the adsorbent retarder to water and stir until well mixed to obtain liquid 1; S2. Add corrosion inhibitor, iron ion stabilizer, acid generator and fluorine source to liquid 1, stir and mix evenly to obtain liquid 2; S3. Add the drainage aid to liquid 2 and stir to form a homogeneous solution.

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