High-temperature-resistant barite blocking remover for deep well and ultra-deep well as well as preparation method and application thereof

Abstract

The invention provides a high-temperature-resistant barite blocking remover for deep wells and ultra-deep wells as well as a preparation method and application of the high-temperature-resistant barite blocking remover. The preparation method of the blocking remover comprises the following steps: adding hyperbranched polyethyleneimine, acrylamide monomers, anionic monomers and polyoxyethylene ether monomers into deionized water to obtain a monomer solution; adjusting the pH value of the monomer solution to 5-9, introducing nitrogen to remove oxygen, heating to a reaction temperature, adding an initiator, and thermally initiating a polymerization reaction; after the reaction is finished, performing vacuum drying and crushing to obtain the high-temperature-resistant hyperbranched polymer dispersing agent. The preparation method comprises the following steps: uniformly mixing a high-temperature-resistant hyperbranched polymer dispersant, an aminopolycarboxylic acid chelating agent and a synergist, adding the mixture into deionized water to obtain a blocking remover aqueous solution, and then adjusting the pH value of the system to 9-11 to obtain the blocking remover. The barite blocking remover is good in high temperature resistance, suitable for barite blocking removal of deep wells at the high temperature of 90-200 DEG C and excellent in blocking removal performance.

Description

Technical Field

[0001] The present invention provides a high-temperature resistant barite plugging removal agent for deep and ultra-deep wells, a preparation method thereof, and an application thereof, belonging to the technical field of oilfield chemistry. Background Art

[0002] With the continuous enhancement of the exploration and development efforts of deep and ultra-deep oil and gas fields, the number of drilling operations for deep and ultra-deep wells has been continuously increasing. During the process of drilling such deep wells, formation high pressure becomes a factor that cannot be ignored, which requires adding heavy materials to the drilling fluid to increase its density, so as to achieve a state of balance with the formation pressure and effectively prevent the occurrence of safety accidents such as well kick and blowout. As a commonly used weighting material for high-density drilling fluid, barite is prone to invade the reservoir through cracks during use, causing reservoir pollution, thereby affecting oil and gas production and economic benefits.

[0003] In recent years, as a weighting material in drilling fluid, the use density of barite has gradually decreased, resulting in an intensified physical settlement phenomenon caused by density differences during the drilling fluid circulation process. Especially after production for a period of time, the settlement speed of barite accelerates with the extension of time, which not only easily blocks the formation, but also the barite content in the mud cake formed by the water loss of the drilling fluid to the formation increases, and there are often associated minerals, causing certain damage to the reservoir in the near-wellbore area. Under the high-temperature and high-pressure environment of the formation, the properties of barite are very stable, and conventional acid plugging removal measures are difficult to dissolve barite blockages. In the long term, it is easy to cause the blockage of oil and gas channels, reduce the permeability of the near-wellbore area, which seriously affects our correct identification of oil and gas layers, may cause misjudgment of oil and gas productivity, thereby reducing the oil recovery rate of the oilfield and affecting economic benefits.

[0004] Chinese patent document CN114539463A provides a barite chelating agent plugging removal material and a preparation method thereof, which can form a chelate with barium ions in barite to achieve the plugging removal of the barite plugging layer in the reservoir, but its corrosion rate at 170°C is only 14.5%. Chinese patent document CN118620589A developed a high-temperature oil and gas well barite chelating plugging removal agent composition with diethylenetriaminepentaacetic acid as the main chelating agent, potassium hydroxide as the pH regulator, and ethylenediaminetetraacetic acid and nitrilotriacetic acid as synergistic synergists. Its corrosion rate at 160°C can reach 74%, but its corrosion rate at 180°C drops to 57%. It can be seen that the corrosion rate at high temperature and ultra-high temperature needs to be further improved. Chinese patent document CN117821044A provides a neutral plugging removal agent through the combination of tetrazole acetic acid quaternary ammonium salt, carboxylate-sulfonate-acrylate terpolymer, surfactant, clay stabilizer, and pH regulator. Its barite corrosion rate at 90°C can reach more than 80%, but the corrosion rate in the high-temperature and ultra-high temperature (>180°C) environment has not been measured.

[0005] In summary, the current barite plugging removal agents have a small dissolution amount and a low effective substance content in high-temperature environments. Therefore, there is an urgent need to develop a high-temperature resistant barite plugging removal agent for deep and ultra-deep wells through a new preparation method, so as to support the safe, efficient and economic drilling of deep and ultra-deep wells. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, especially the technical problem of low dissolution rate of existing barite plugging removal agents in high-temperature environments of deep wells, the present invention provides a high-temperature resistant barite plugging removal agent for deep and ultra-deep wells, its preparation method and application. The barite plugging removal agent of the present invention has good high-temperature resistance and is suitable for barite plugging removal in high-temperature deep wells of 90°C - 200°C.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A preparation method of a high-temperature resistant barite plugging removal agent for deep and ultra-deep wells, comprising the following steps:

[0009] (1) Add hyperbranched polyethyleneimine, acrylamide monomer, anionic monomer, and polyoxyethylene ether monomer to deionized water to obtain a monomer solution; after adjusting the pH of the monomer solution to 5 - 9, purge with nitrogen to remove oxygen, then raise the temperature to the reaction temperature, add an initiator, and carry out thermal-initiated polymerization reaction; after the reaction is completed, perform vacuum drying and pulverization to obtain a high-temperature resistant hyperbranched polymer dispersant.

[0010] (2) Mix the high-temperature resistant hyperbranched polymer dispersant, aminopolycarboxylic acid chelating agent, and synergist obtained in step (1) evenly to obtain a plugging removal agent composition, add the obtained plugging removal agent composition to deionized water to obtain a plugging removal agent aqueous solution, and then adjust the system pH to 9 - 11 to obtain a high-temperature resistant barite plugging removal agent for deep and ultra-deep wells.

[0011] Preferably according to the present invention, in step (1), the number-average molecular weight of the hyperbranched polyethyleneimine is 800 - 1800 g / mol.

[0012] Preferably according to the present invention, in step (1), the acrylamide monomer is methacrylamide (MAM) or N,N-dimethylacrylamide (DMAA).

[0013] Preferably according to the present invention, in step (1), the anionic monomer is 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and / or sodium styrenesulfonate (SSS).

[0014] Preferably according to the present invention, in step (1), the polyoxyethylene ether monomer is one or a combination of two or more of methyl vinyl polyoxyethylene ether (TPEG), allyl polyoxyethylene ether (APEG), and polyethylene glycol monomethyl ether (MPEG); the methyl vinyl polyoxyethylene ether is TPEG-800, TPEG-1000, or TPEG-2400; the allyl polyoxyethylene ether is APEG-600, APEG-700, APEG-800, or APEG-1000; the polyethylene glycol monomethyl ether is MPEG-350, MPEG-400, MPEG-450, MPEG-500, MPEG-750, or MPEG-1000.

[0015] Preferably according to the present invention, in step (1), the mass ratio of the acrylamide monomer, the anionic monomer, and the polyoxyethylene ether monomer is 1-7:1-2:1-2, more preferably 3-5:1-2:1-2; the total mass fraction of the monomer solution is 10-40%, more preferably 15-20%; the total mass of the monomers refers to the sum of the masses of the acrylamide monomer, the anionic monomer, and the polyoxyethylene ether monomer.

[0016] Preferably according to the present invention, in step (1), the mass ratio of the hyperbranched polyethyleneimine to the total mass of the acrylamide monomer, the anionic monomer, and the polyoxyethylene ether monomer is 0.1-0.25:1.

[0017] Preferably according to the present invention, in step (1), a NaOH aqueous solution with a mass fraction of 20-30% is used to adjust the pH of the monomer solution to 5-9.

[0018] Preferably according to the present invention, in step (1), the initiator is ammonium cerium nitrate (CAN); the mass ratio of the initiator to the total mass of the acrylamide monomer, the anionic monomer, and the polyoxyethylene ether monomer is 0.01-0.05:1, more preferably 0.03-0.04:1.

[0019] Preferably according to the present invention, in step (1), the reaction temperature is 30-80°C, more preferably 50-70°C; the polymerization reaction time is 2-6 h, more preferably 3-5 h.

[0020] Preferably according to the present invention, in step (1), the temperature of the vacuum drying is 30-70°C, more preferably 40-60°C; the time of the vacuum drying is 3-7 h, more preferably 4-6 h.

[0021] Preferably according to the present invention, in step (2), the aminopolycarboxylic acid chelating agent is a combination of two of diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEDTA).

[0022] Preferably according to the present invention, the synergist in step (2) is a mixture of ethylenediaminetetraacetic acid and nitrilotriacetic acid, and the mass ratio of ethylenediaminetetraacetic acid to nitrilotriacetic acid in the mixture is 1-2:1-2, more preferably 1:1.

[0023] Preferably according to the present invention, the mass ratio of the high-temperature resistant hyperbranched polymer dispersant, aminopolycarboxylic acid chelating agent to the synergist in step (2) is 1.5-2:1.5-2:1.

[0024] Preferably according to the present invention, the mass concentration of the plugging removal agent composition in the aqueous solution of the plugging removal agent in step (2) is 10-40 wt%.

[0025] Preferably according to the present invention, a NaOH aqueous solution with a mass fraction of 20-30% is used in step (2) to adjust the pH of the monomer solution to 9-11.

[0026] The present invention also provides a high-temperature resistant barite plugging removal agent for deep wells and ultra-deep wells, which is prepared by the above preparation method.

[0027] According to the present invention, the above application of the high-temperature resistant barite plugging removal agent for deep wells and ultra-deep wells is used for plugging removal of barite.

[0028] The technical features and beneficial effects of the present invention are as follows:

[0029] 1. The preparation process of the barite plugging removal agent of the present invention is simple, the raw materials are easy to obtain, the synthesis temperature and time are easy to control, the obtained plugging removal agent has a low cost, is convenient for transportation, has a simple usage method, can be mixed online, and is suitable for large-scale use in oil fields.

[0030] 2. The high-temperature resistant hyperbranched polymer dispersant is added to the plugging removal agent of the present invention, which can effectively reduce the interaction force between barite particles, prevent their agglomeration and sedimentation, improve the dispersion stability of barite in the plugging removal agent, enable the plugging removal agent to fully contact with barite, and improve the plugging removal efficiency.

[0031] 3. The barite plugging removal agent of the present invention contains an aminopolycarboxylic acid chelating agent, has a large dissolution amount of barite, a high dissolution efficiency, and good high-temperature resistance, and is suitable for plugging removal of barite in high-temperature deep wells at 90°C to 200°C.

[0032] 4. The carboxyl group in the plugging removal agent of the present invention can achieve a relatively high clearance rate for the associated minerals generated by barite sedimentation, and the high stability constant of the plugging removal agent can effectively prevent the ion exchange between the barium ion chelate in the plugging removal agent and rock minerals, and will not damage the original skeleton structure of the reservoir, greatly improving the recovery value of the permeability in the near-well area of the oil field. Specific embodiments

[0033] The present invention will be further described below through specific embodiments, but it is not limited thereto.

[0034] In the experimental methods described in the embodiments, unless otherwise specified, they are all conventional methods; the reagents and materials used, unless otherwise specified, can all be obtained from commercial channels.

[0035] Example 1

[0036] A preparation method of a high-temperature resistant barite plugging removal agent for deep wells and ultra-deep wells includes the following steps:

[0037] (1) Synthesis of high-temperature resistant hyperbranched polymer dispersant

[0038] Dissolve 5 g of N,N-dimethylacrylamide (DMAA), 2 g of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 2 g of methoxypolyethylene glycol (MPEG-400), and 1.35 g of hyperbranched polyethyleneimine (number average molecular weight of 800 g / mol) in 45 g of deionized water to obtain a monomer solution; under stirring conditions, slowly add (1 drop / s) an aqueous solution of 25% NaOH to the obtained monomer solution to adjust the pH value of the monomer solution to 8 to obtain a mixed reaction solution; deoxygenate the obtained mixed reaction solution under nitrogen protection for 30 min, then raise the temperature to 60 °C, add 0.27 g of initiator ammonium cerium nitrate (CAN), and carry out a polymerization reaction at 60 °C for 5 h. After the reaction is completed, place the obtained product in a vacuum drying oven at 60 °C for drying for 5 h and then pulverize it to obtain a high-temperature resistant hyperbranched polymer dispersant.

[0039] (2) Preparation of high-temperature resistant barite plugging removal agent

[0040] Mix the high-temperature resistant hyperbranched polymer dispersant, amino polycarboxylic acid chelating agent, and synergist evenly according to a mass ratio of 1.5:1.5:1 to obtain a plugging removal agent composition. Add the obtained plugging removal agent composition to deionized water to prepare a plugging removal agent aqueous solution with a mass concentration of 15 wt% of the plugging removal agent composition, and then use an aqueous solution of 25% NaOH to adjust the pH of the system to 10 to obtain a high-temperature resistant barite plugging removal agent for deep wells and ultra-deep wells;

[0041] The amino polycarboxylic acid chelating agent is a composition of ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), and the mass ratio of ethylenediaminetetraacetic acid (EDTA) to diethylenetriaminepentaacetic acid (DTPA) is 1:1;

[0042] The synergist is a composition of ethylenediaminetetraacetic acid and nitrilotriacetic acid, and the mass ratio of ethylenediaminetetraacetic acid to nitrilotriacetic acid is 1:1.

[0043] Example 2

[0044] The preparation method of a high-temperature resistant barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the mass concentration of the plugging remover aqueous solution is 10 wt%.

[0045] Example 3

[0046] The preparation method of a high-temperature resistant barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the mass concentration of the plugging remover aqueous solution is 20 wt%.

[0047] Example 4

[0048] The preparation method of a high-temperature resistant barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the mass concentration of the plugging remover aqueous solution is 25 wt%.

[0049] Example 5

[0050] The preparation method of a high-temperature resistant barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the mass concentration of the plugging remover aqueous solution is 30 wt%.

[0051] Example 6

[0052] The preparation method of a high-temperature resistant barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the mass concentration of the plugging remover aqueous solution is 40 wt%.

[0053] Example 7

[0054] The preparation method of a high-temperature resistant barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (1), an equal mass of methylacrylamide (MAM) is used to replace N,N-dimethylacrylamide (DMAA), and other conditions and component ratios are the same as those in Example 1.

[0055] Example 8

[0056] The preparation method of a high-temperature resistant barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the aminopolycarboxylic acid chelating agent is a combination of diethylenetriaminepentaacetic acid (DTPA) and hydroxyethylenediaminetriacetic acid (HEDTA), and the mass ratio of diethylenetriaminepentaacetic acid (DTPA) to hydroxyethylenediaminetriacetic acid (HEDTA) is 1:1.

[0057] Comparative Example 1

[0058] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (1), the addition amount of polyethylene glycol monomethyl ether (MPEG) is 0 g.

[0059] Comparative Example 2

[0060] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the addition amount of the high-temperature resistant hyperbranched polymer dispersant is 0 g.

[0061] Comparative Example 3

[0062] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (2), the addition amount of the synergist is 0 g.

[0063] Comparative Example 4

[0064] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (1), an equal mass of ammonium persulfate (APS) is used to replace ammonium cerium nitrate (CAN), and other conditions and component ratios are the same as those in Example 1.

[0065] Comparative Example 5

[0066] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (1), N,N-dimethylacrylamide (DMAA) is not added.

[0067] Comparative Example 6

[0068] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (1), 2-acrylamido-2-methylpropanesulfonic acid (AMPS) is not added.

[0069] Comparative Example 7

[0070] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (1), an equal mass of acrylamide (AM) is used to replace N,N-dimethylacrylamide (DMAA), and other conditions and component ratios are the same as those in Example 1.

[0071] Comparative Example 8

[0072] The preparation method of a barite plugging remover for deep and ultra-deep wells is as described in Example 1, except that: in step (1), an equal mass of sodium vinyl sulfonate (VS) is used to replace 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and other conditions and component ratios are the same as those in Example 1.

[0073] Comparative Example 9

[0074] The preparation method of a barite plugging removal agent for deep wells and ultra - deep wells is as described in Example 1, except that: in step (2), the high - temperature - resistant hyperbranched polymer dispersant, amino polycarboxylic acid chelating agent, and synergist are mixed evenly in a mass ratio of 1:1:1, and other conditions and component ratios are the same as those in Example 1.

[0075] Comparative Example 10

[0076] The preparation method of a barite plugging removal agent for deep wells and ultra - deep wells is as described in Example 1, except that: in step (2), an equal - mass common polycarboxylate dispersant (polyacrylic acid (PAA)) is used to replace the high - temperature - resistant hyperbranched polymer dispersant, and other conditions and component ratios are the same as those in Example 1.

[0077] Test Example 1

[0078] Evaluate each example and comparative example according to the following method

[0079] Experimental method for evaluating the dissolution rate of barite at high temperature under static conditions

[0080] 1. Main instruments and equipment

[0081] a) High - temperature roller furnace: A high - temperature roller heating furnace for drilling fluids that meets the GB / T 16783.1 - 2006 standard, with a temperature control range of 0 - 200 °C and an accuracy of ±5 °C;

[0082] b) High - temperature aging tank: Made of stainless steel;

[0083] c) Electro - thermal constant - temperature drying oven: With a temperature control range of 0 - 200 °C and a temperature control sensitivity of ±2 °C;

[0084] d) Quick - quantitative filter paper: With a diameter of 15 cm;

[0085] e) Electronic balance: With a sensitivity of 0.001 g;

[0086] f) Funnel: With a diameter of 15 cm.

[0087] 2. Main reagents and materials

[0088] a) Barite powder: Analytical - grade barium sulfate;

[0089] b) Deionized water: Laboratory - used deionized water that meets the GB / T 6682 - 2008 standard;

[0090] 3. Test method for barite dissolution rate

[0091] a) Respectively take 100 mL of the plugging removal agents prepared in the examples and comparative examples, and add accurately weighed barium sulfate (2 g, denoted as m 1 ) to the plugging removal agents, and mix them evenly.

[0092] b) Add the mixed solution obtained in step (a) to a high-temperature aging tank and place it under static conditions at temperatures of 150 °C, 180 °C, and 200 °C for reaction, with a reaction duration of 16 h;

[0093] c) After the dissolution reaction is completed, take out the aging tank from the roller furnace. When it has cooled to room temperature, open the sealing cover and take out the plugging removal agent liquid;

[0094] d) Place a quantitative filter paper in an oven at 120 °C and dry it to a constant weight (record its mass as m 2 );

[0095] e) Use a quantitative filter paper and filter the plugging removal agent liquid after the corrosion reaction through a funnel. Rinse the barite residue that has not been dissolved with test water until the pH value of the filtrate is 7;

[0096] f) Place the residue together with the filter paper in an oven at 120 °C and dry it to a constant weight (record its mass as m 3 );

[0097] g) Calculate the barite dissolution rate.

[0098] 4. Judgment of dissolution rate results

[0099]

[0100] In the formula:

[0101] η - corrosion rate, %; m 1 - mass of barium sulfate before the test, g; m 2 - mass of the quantitative filter paper, g; m 3 - mass of the filter paper + barium sulfate after the test, g.

[0102] The corrosion rate results of the plugging removal agent samples in the examples and comparative examples at 150, 180, and 200 °C with a reaction time of 16 h are shown in Table 1.

[0103] Table 1 Measurement results of the high-temperature static barite dissolution rate of the plugging removal agent at 150 °C, 180 °C, and 200 °C

[0104]

[0105]

[0106]

[0107] As can be seen from Table 1, through Examples 1-8, it can be obtained that the barite plugging removal agent obtained by mixing a high-temperature resistant hyperbranched polymer dispersant, an aminopolycarboxylic acid chelating agent and a synergist has good plugging removal efficiency at high temperature, and the corrosion rate can reach 80% or more. Among them, the concentration of the plugging removal agent composition has a significant influence on the dissolution efficiency. Due to the difference in molecular structure, different formulations of the plugging removal agent have their own optimal dissolution concentrations. Through Examples 1-6, it can be obtained that the dissolution efficiency is the best when the concentration of the plugging removal agent is 15%. Under high-temperature conditions, the corrosion rate of the plugging removal agent can basically remain at 80% or more, showing good high-temperature resistance. By comparing the dissolution rate data at different temperatures, the dissolution rate of barite is relatively high at 180°C, which can be regarded as the optimal use temperature of the plugging removal agent of the present invention. At this temperature, the dissolution rate of barite in some examples can reach more than 92%.

[0108] By comparing the data of the examples and comparative examples, in Comparative Example 1, polyethylene glycol monomethyl ether (MPEG) is not contained, which reduces the degree of branching of the hyperbranched polymer and the high-temperature resistance; in Comparative Example 2, the high-temperature resistant hyperbranched polymer dispersant is not contained, resulting in a large molecular weight of the linear polymer in the plugging removal agent. The polymer chain is easily degraded at high temperature, the high-temperature resistance becomes poor, and the dissolution rate of the plugging removal agent is greatly reduced; in Comparative Example 3, the synergist is not contained, resulting in a decrease in the wettability of the plugging removal agent and the re-aggregation of clay particles, and the plugging removal efficiency decreases; in Comparative Example 4, ammonium persulfate (APS) is used instead of ammonium cerium nitrate (CAN) of the present invention, and an oxidation-reduction initiation system of ammonium cerium nitrate and hydroxyl cannot be formed, which hinders the initiation of the hyperbranched polymer chain and generates more linear polymer network structures, and the high-temperature resistance becomes poor; in Comparative Example 5, N,N-dimethylacrylamide monomers are not contained, and the fluidity and dispersibility of the plugging removal agent are weakened at high temperature, and the plugging removal effect becomes poor; in Comparative Example 6, high-temperature resistant anionic hydration monomers are not contained, and the aggregation effect of clay particles is obvious at high temperature, and the plugging removal performance deteriorates; in Comparative Example 7, acrylamide (AM) is directly used instead of N,N-dimethylacrylamide (DMAA), and the polymerization degree of the hyperbranched polymer is reduced, and the high-temperature resistance is reduced; in Comparative Example 8, sodium vinyl sulfonate (VS) is used instead of 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and the molecular chain is easily degraded in a high-temperature environment, and the plugging removal property fails. In Comparative Example 9, the ratio of the dispersant, chelating agent and synergist is changed, and its plugging removal performance is lower than that of Example 1, indicating that the ratio of the three has an important influence on the performance of the plugging removal agent. In Comparative Example 10, a common polycarboxylate dispersant is used to replace the high-temperature resistant hyperbranched polymer dispersant of the present invention, and the dissolution rate of the plugging removal agent is lower than that of Example 1, highlighting the advantage of the dispersant of the present invention in improving the performance of the plugging removal agent.

[0109] In summary, aiming at the problem of reservoir damage caused by barite invasion in high-pressure reservoirs during high-density drilling fluid operations, a highly efficient corrosion dissolution plugging removal agent with high temperature resistance and a corrosion dissolution rate of up to 92% was developed through the synergistic effect of a high-temperature resistant hyperbranched polymer dispersant, an aminopolycarboxylic acid chelating agent, and a synergist; this plugging removal agent has a high active ingredient content, a simple production process, convenient storage and transportation, and a high cost performance, and is a type of barite plugging removal agent for high-temperature oil and gas wells that can efficiently remove barite blockages.

Claims

1. A method for preparing a high temperature resistant barite plugging remover for deep wells and ultra-deep wells, comprising the following steps: (1) adding hyperbranched polyethyleneimine, acrylamide monomers, anionic monomers, and polyoxyethylene ether monomers into deionized water to obtain a monomer solution; adjusting the pH of the monomer solution to 5 to 9, passing nitrogen to deoxygenate, then heating to a reaction temperature, adding an initiator, and thermally initiating a polymerization reaction; after the reaction is completed, vacuum drying and pulverizing to obtain a high temperature resistant hyperbranched polymer dispersant; (2) The high temperature resistant hyperbranched polymer dispersant, aminopolycarboxylic acid chelating agent and synergist obtained in step (1) are uniformly mixed to obtain a plugging remover composition, and the obtained plugging remover composition is added into deionized water to obtain a plugging remover aqueous solution, and then the pH of the system is adjusted to 9-11 to obtain a high temperature resistant barite plugging remover for deep wells and ultra-deep wells.

2. The method for preparing the high temperature resistant barite plugging remover for deep wells and ultra-deep wells according to claim 1, characterized in that: The number average molecular weight of the hyperbranched polyethyleneimine in step (1) is 800 to 1800 g / mol; The acrylamide monomer is methacrylamide or N,N-dimethylacrylamide; the anionic monomer is 2-acrylamido-2-methylpropanesulfonic acid and / or sodium styrenesulfonate; the polyoxyethylene ether monomer is one or a combination of two or more of methylalkenyl polyoxyethylene ether, allyl polyoxyethylene ether, and polyethylene glycol monomethyl ether; the methylalkenyl polyoxyethylene ether is TPEG-800, TPEG-1000 or TPEG-2400; the allyl polyoxyethylene ether is APEG-600, APEG-700, APEG-800 or APEG-1000; the polyethylene glycol monomethyl ether is MPEG-350, MPEG-400, MPEG-450, MPEG-500, MPEG-750 or MPEG-1000.

3. The preparation method of the high temperature resistant barite plugging remover for deep well and ultra-deep well according to claim 1, characterized in that, The mass ratio of the acrylamide monomer, the anionic monomer and the polyoxyethylene ether monomer in step (1) is 1-7:1-2:1-2, preferably 3-5:1-2:1-2; the total mass fraction of the monomer solution is 10-40%, preferably 15-20%; the total mass of the monomers refers to the sum of the masses of the acrylamide monomer, the anionic monomer and the polyoxyethylene ether monomer.

4. The method for preparing the high temperature resistant barite plugging remover for deep wells and ultra-deep wells according to claim 1, characterized in that: The ratio of the mass of the hyperbranched polyethyleneimine to the total mass of the acrylamide monomers, the anionic monomers and the polyoxyethylene ether monomers in step (1) is 0.1 to 0.25:

1.

5. The method for preparing the high temperature resistant barite plugging remover for deep wells and ultra-deep wells according to claim 1, characterized in that: In step (1), a 20-30% by mass NaOH aqueous solution is used to adjust the pH of the monomer solution to 5-9; The initiator is ammonium cerium nitrate; the ratio of the mass of the initiator to the total mass of the acrylamide monomer, the anion monomer and the polyoxyethylene ether monomer is 0.01 to 0.05:1, preferably 0.03 to 0.04:1; The reaction temperature is 30 to 80° C., preferably 50 to 70° C.; the polymerization reaction time is 2 to 6 hours, preferably 3 to 5 hours; The vacuum drying temperature is 30 to 70° C., preferably 40 to 60° C.; the vacuum drying time is 3 to 7 hours, preferably 4 to 6 hours.

6. The method for preparing the high temperature resistant barite plugging remover for deep wells and ultra-deep wells according to claim 1, characterized in that: The aminopolycarboxylic acid chelating agent in step (2) is a combination of two of diethylenetriaminepentaacetic acid, ethylenediaminetetraacetic acid, and hydroxyethylethylenediaminetriacetic acid; The synergist is a mixture of ethylenediaminetetraacetic acid and nitrilotriacetic acid, and the mass ratio of ethylenediaminetetraacetic acid to nitrilotriacetic acid in the mixture is 1-2:1-2, preferably 1:

1.

7. The method for preparing the high temperature resistant barite plugging remover for deep wells and ultra-deep wells according to claim 1, characterized in that: The mass ratio of the high temperature resistant hyperbranched polymer dispersant, the aminopolycarboxylic acid chelating agent and the synergist in step (2) is 1.5-2:1.5-2:

1.

8. The method for preparing the high temperature resistant barite plugging remover for deep wells and ultra-deep wells according to claim 1, characterized in that: The mass concentration of the blocking agent composition in the blocking agent aqueous solution in step (2) is 10 to 40 wt %; In step (2), a NaOH aqueous solution with a mass fraction of 20 to 30% is used to adjust the pH of the monomer solution to 9 to 11.

9. A high temperature resistant barite plugging remover for deep wells and ultra-deep wells, characterized in that: The preparation method according to claim 1 is used for preparation.

10. Use of the high temperature resistant barite plugging remover for deep wells and ultra-deep wells as claimed in claim 9 for removing barite plugging.

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