Seawater instant salt-resistant polyacrylamide as well as preparation process and device thereof

Abstract

The invention discloses seawater instant salt-resistant polyacrylamide and a preparation process and device thereof, and relates to the field of polyacrylamide, the seawater instant salt-resistant polyacrylamide comprises the following components by mass: 90-96% of a polyacrylamide monomer and 4-10% of a cosolvent; the polyacrylamide monomer comprises a carboxylic acid group; the carboxylic acid group is introduced into a molecular chain of the polyacrylamide monomer in a copolymerization manner; the cosolvent is urea and / or formamide. The method has the advantages that the efficiency of dissolving the seawater instant salt-resistant polyacrylamide in seawater is improved, the viscosity of the solution is improved, and the oil displacement effect is ensured.

Description

Technical Field

[0001] The present application relates to the field of polyacrylamide, and in particular to seawater-soluble salt-resistant polyacrylamide and its preparation process and device. Background Art

[0002] In the early stage of oil development, the formation pressure is sufficient and the oil wells rely on natural energy to produce by self-flowing. As the oil field development progresses, the formation pressure gradually weakens and it is difficult for the oil wells to produce by self-flowing. At this time, the crude oil recovery rate is generally 10%. To further increase crude oil production, water injection wells need to be deployed to inject water into the oil layer, pressurize the oil in the formation to drive the oil to the bottom of the oil well, and then lift it to the ground, thereby increasing crude oil production. The recovery rate generally only reaches about 40%. To better improve the recovery rate, tertiary oil recovery chemical drive is carried out for water-driven oil fields. Polyacrylamide aqueous solution is injected into the injection well to change the mobility ratio, expand the swept volume, improve the displacement effect, and maximize the crude oil recovery rate.

[0003] The existing patent application document with publication number CN116987217A discloses a preparation method of polyacrylamide, polyacrylamide and application. The preparation method of polyacrylamide includes: monomer production technology: acrylonitrile is used as raw material in the production of acrylamide monomer, which is hydrated under the action of a catalyst to generate a crude product of acrylamide monomer, and refined acrylamide monomer is obtained after flash evaporation and refining. This monomer is the production raw material of polyacrylamide; polymerization technology: acrylamide aqueous solution is used as raw material, and a polymerization reaction is carried out under the action of an initiator. After the reaction is completed, the polyacrylamide block generated is cut, granulated, dried, and crushed to finally obtain a polyacrylamide product.

[0004] When ordinary polyacrylamide is used for marine oil and gas displacement exploitation, polyacrylamide is usually dissolved in seawater for oil displacement because of the limited freshwater resources on offshore drilling platforms. However, seawater has a high mineralization degree and complex chemical composition, and contains a large number of electrolytes, such as sodium chloride and magnesium chloride, which will ionize a large number of ions after dissolution. Polyacrylamide molecular chains usually carry some charges (such as negative charges after carboxyl ionization). Ions in seawater will more easily approach and shield the charges on the polyacrylamide molecular chains, resulting in a weakening of the electrostatic repulsion between the molecular chains, which causes the molecular chains to curl and break, resulting in a decrease in the viscosity of the polyacrylamide solution and a weakening of the oil displacement effect; in addition, polyacrylamide dissolves slowly in seawater, and the area of ​​offshore drilling platforms is limited, requiring the injection equipment to be simplified and occupy a small area, so it is urgent to improve the performance of polyacrylamide, speed up the dissolution rate and increase the viscosity. Summary of the invention

[0005] In order to improve the dissolution rate and viscosity-increasing property of polyacrylamide in seawater, the present application provides seawater-soluble salt-resistant polyacrylamide and its preparation process and device.

[0006] In the first aspect, the present application provides a seawater-soluble salt-resistant polyacrylamide, which adopts the following technical solution: Seawater fast-soluble salt-resistant polyacrylamide, including the following components in mass ratio: polyacrylamide monomer 90-96%, co-solvent 4%-10%; The polyacrylamide monomer includes a carboxylic acid group.

[0007] By adopting the above technical solution, polyacrylamide is dissolved in seawater, and polyacrylamide containing carboxylic acid groups can maintain good performance stability and is not easily affected by salt and becomes ineffective; at the same time, the cosolvent can make the polyacrylamide dissolve in seawater faster. In this way, the efficiency of the seawater fast-soluble salt-resistant polyacrylamide dissolving in seawater is improved, the viscosity of the solution is increased, and the oil displacement effect is guaranteed.

[0008] Preferably, the carboxylic acid group is introduced into the molecular chain of the polyacrylamide monomer by copolymerization.

[0009] By adopting the above technical solution, the carboxylic acid group is introduced into the molecular chain of the polyacrylamide monomer.

[0010] Preferably, the co-solvent is urea and / or formamide.

[0011] In the second aspect, the present application provides a process for preparing seawater-soluble salt-resistant polyacrylamide, which adopts the following technical solution: mixing acrylamide monomer with acrylic acid to form a mixed solution; adding an initiator to the mixture; Performing a polymerization reaction on the mixed solution to which the initiator is added, thereby obtaining a polymer solution; Drying the polymer solution and granulating the dried polymer solution to form polyacrylamide particles; The preparation is completed by mixing the polyacrylamide particles and the co-solvent.

[0012] By adopting the above technical scheme, acrylamide monomer, acrylic acid and initiator are mixed to carry out polymerization reaction, wherein the initiator is used to initiate a chain reaction to generate a polymerization liquid (polyacrylamide); then, the polymerization liquid is dried and granulated in sequence to form polyacrylamide particles; finally, the polyacrylamide particles and the co-solvent are mixed to complete the preparation of seawater-soluble salt-resistant polyacrylamide, thereby realizing the preparation of seawater-soluble salt-resistant polyacrylamide.

[0013] Preferably, the initiator is ammonium persulfate.

[0014] By adopting the above technical scheme, the chain reaction is initiated by ammonium persulfate, thereby ensuring the normal polymerization reaction of acrylamide monomer and acrylic acid.

[0015] Preferably, the temperature of the polymerization reaction is controlled between 50-65 degrees Celsius; the pressure of the polymerization reaction is controlled between 0.1-0.5 MPa.

[0016] By adopting the above technical solution, the polymerization reaction of acrylamide monomer and acrylic acid can be carried out stably.

[0017] Preferably, before adding the initiator, sodium hydroxide solution is added to the mixed solution to adjust the pH value of the mixed solution to [6-7].

[0018] By adopting the above technical solution, the polymerization reaction of acrylamide monomer and acrylic acid can be carried out stably.

[0019] Preferably, during the polymerization reaction, the mixed solution is continuously stirred.

[0020] The adoption of the above technical solution helps to ensure the sufficiency of the polymerization reaction of acrylamide monomer and acrylic acid.

[0021] In the third aspect, the present application provides a device for preparing seawater-soluble salt-resistant polyacrylamide, which adopts the following technical solution: A seawater instant salt-resistant polyacrylamide preparation device, used for polymerization reaction in the seawater instant salt-resistant polyacrylamide preparation process, comprises a reaction kettle, the reaction kettle comprises a kettle body, a solution cavity is formed in the kettle body, a sealing cover is arranged on the upper side of the kettle body, a stirring shaft is rotatably arranged on the sealing cover, the stirring shaft is arranged downward and extends into the kettle body, a lift blade is fixed on the stirring shaft, one side of the lift blade is close to the stirring shaft and fixed to the stirring shaft, the other side of the lift blade extends toward the side away from the stirring shaft, the lift blade is located in the kettle body, and the lift blade is arranged upwardly in an inclined manner; A guide ridge is fixed on the inner wall of the reaction kettle, and the guide ridge surrounds the reaction kettle and is spiral.

[0022] By adopting the above technical solution, in actual use, acrylamide monomer, acrylic acid and initiator are all placed in a reactor; then, the stirring shaft is rotated, and the lift blades will drive the solution in the reactor to rotate, and the solution in the reactor will surge up under the guidance of the lift blades, while the solution close to the side wall of the reactor will flow downward under the guidance of the guide ridges, so that the middle solution in the reactor surges up and the outer solution flows downward, and the cycle is repeated, which helps to improve the uniformity of the mixing of acrylamide monomer, acrylic acid and initiator, and helps to improve the sufficiency of the copolymerization reaction of acrylamide monomer and acrylic acid.

[0023] Preferably, a baffle plate is provided on the side of the lift blade facing away from the stirring shaft, and the baffle plate is arranged along the inclination direction of the lift blade.

[0024] By adopting the above technical solution, the movement of the middle solution in the reactor and the movement of the outer solution are blocked by the blocking plate, which helps to ensure the stability of the upward flow of the middle solution in the reactor and the downward flow of the outer solution, and ensure the adequacy of the copolymerization reaction of acrylamide monomer and acrylic acid.

[0025] In summary, the present application includes at least one of the following beneficial technical effects: By introducing carboxylic acid groups into polyacrylamide monomers and mixing the polyacrylamide monomers and co-solvents in proportion, the efficiency of the seawater fast-soluble salt-resistant polyacrylamide in dissolving in seawater is improved, the viscosity of the solution is increased, and the oil displacement effect is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an axonometric diagram of the overall structure of the instant seawater-soluble salt-resistant polyacrylamide device of this embodiment; Figure 2 This is an exploded schematic diagram mainly showing the stirring device and the guide ridge structure of this embodiment.

[0027] Figure numerals: 1. Reactor; 2. Reactor body; 21. Solution chamber; 211. Guide ridge; 22. Sealing cover; 221. Feeding pipe; 23. Medium inlet; 24. Medium outlet; 25. Discharging pipe; 3. Stirring device; 31. Variable frequency motor; 32. Stirring shaft; 321. Lift blade; 322. Blocking plate. DETAILED DESCRIPTION

[0028] The present application is further described in detail below in conjunction with the accompanying drawings.

[0029] The examples of the present application disclose seawater-soluble salt-resistant polyacrylamide.

[0030] Reference Figure 1 The seawater-soluble salt-resistant polyacrylamide comprises the following components in mass ratio: 90-96% of polyacrylamide monomer and 4%-10% of cosolvent; the polyacrylamide monomer comprises a carboxylic acid group. The carboxylic acid group is introduced into the molecular chain of the polyacrylamide monomer by copolymerization. Moreover, the cosolvent may be urea and / or formamide. In this embodiment, the cosolvent is preferably urea.

[0031] The implementation principle of the seawater fast-soluble salt-resistant polyacrylamide in the embodiment of the present application is: when polyacrylamide is dissolved in seawater, the polyacrylamide containing carboxylic acid groups can maintain good performance stability and is not easily affected by salt and become ineffective; at the same time, the cosolvent can make the polyacrylamide dissolve in seawater faster.

[0032] The examples of the present application also disclose a process for preparing seawater-soluble salt-resistant polyacrylamide.

[0033] Seawater-soluble salt-resistant polyacrylamide and its preparation process include the following steps: S1. Place acrylamide monomer and acrylic acid in a reaction kettle and mix them to form a mixed solution; and add sodium hydroxide solution to the mixed solution to adjust the pH value of the mixed solution to [6-7). Preferably, the pH value of the mixed solution is adjusted to 6.5.

[0034] Stirring is performed when the acrylamide monomer and acrylic acid are mixed and when the sodium hydroxide solution is added.

[0035] S2, adding an initiator to the mixed solution; S3, heating the solution in the reactor to 50-65 degrees Celsius, and maintaining the temperature of the solution in the reactor between 50-65 degrees Celsius, and a thermometer can be set on the reactor to monitor the temperature of the solution. At the same time, nitrogen is filled into the reactor to control the pressure in the reactor at 0.1-05MPa. Thus, the mixed solution is polymerized to obtain a polymer solution.

[0036] In a preferred embodiment, the temperature of the solution in the reactor can be controlled at 60 degrees Celsius, and the pressure in the reactor can be controlled at 0.3 MPa.

[0037] S4, drying the polymer solution, and granulating the dried polymer solution to form polyacrylamide particles. In this embodiment, a boiling granulation dryer can be used to dry and granulate the polymer solution.

[0038] S5. Mix the polyacrylamide particles and the solvent to complete the preparation.

[0039] The present application also discloses a device for preparing seawater-soluble salt-resistant polyacrylamide.

[0040] See also Figure 1 and Figure 2 , a seawater fast-soluble salt-resistant polyacrylamide preparation device, used for polymerization reaction in the seawater fast-soluble salt-resistant polyacrylamide preparation process. It includes a reactor 1, the reactor 1 includes a reactor body 2 and a stirring device 3, the reactor body 2 is provided with a solution cavity 21, the solution cavity 21 is a cylindrical space, and the side wall and the bottom wall of the solution cavity 21 are connected by a smooth transition of an arc surface. A sealing cover 22 is fixed on the upper side of the reactor body 2, and the stirring device 3 is located on the sealing cover 22 and is used to stir the solution in the solution cavity 21.

[0041] Specifically, the stirring device 3 includes a variable frequency motor 31 and a stirring shaft 32. The variable frequency motor 31 is fixed on the sealing cover 22, and the output shaft of the variable frequency motor 31 is arranged vertically downward. The stirring shaft 32 is located at the lower side of the variable frequency motor 31, the stirring shaft 32 is coaxial with the solution chamber 21, the upper end of the stirring shaft 32 is drivingly connected with the output shaft of the variable frequency motor 31, the lower side of the stirring shaft 32 passes through the sealing cover 22 and extends into the solution chamber 21, and the stirring shaft 32 is rotatably connected with the sealing cover 22 through a bearing. In this embodiment, the upper end of the stirring shaft 32 is coaxially fixed with the output shaft of the variable frequency motor 31, and a sealing ring can be used to seal between the stirring shaft 32 and the sealing cover 22 to maintain the pressure in the solution chamber 21.

[0042] The portion of the stirring shaft 32 located at the lower side of the sealing cover 22 is fixed with a lift blade 321, one side of the lift blade 321 is close to the stirring shaft 32 and fixed to the stirring shaft 32, and the other side of the lift blade 321 extends toward the side away from the stirring shaft 32. The lift blade 321 is arranged upwardly at an angle, and when the lift blade 321 rotates with the stirring shaft 32, it can drive the solution to move upward. There are multiple groups of lift blades 321 evenly spaced on the stirring shaft 32 in the vertical direction, and each group of lift blades 321 includes multiple lift blades 321 evenly spaced around the stirring shaft 32. In this embodiment, there are three groups of lift blades 321 in the vertical direction, and each group of lift blades 321 includes three lift blades 321.

[0043] A guide ridge 211 is fixed on the side wall of the solution chamber 21, and the guide ridge 211 surrounds the reactor 1 and is spiral. When the lift blade 321 rotates with the stirring shaft 32, the solution will be driven to rotate. At this time, the guide ridge 211 will guide the outer solution to flow downward. In order to reduce the interference between the upward movement of the middle solution in the solution chamber 21 and the downward flow of the outer solution, a blocking plate 322 is fixed on the side of each lift blade 321 away from the stirring shaft 32. The blocking plate 322 is perpendicular to the lift blade 321, and the blocking plate 322 is arranged along the inclination direction of the lift blade 321.

[0044] At the same time, the side wall of the kettle body 2 is an inner and outer double-layer structure, a heat exchange chamber is formed between the inner wall and the outer wall of the kettle body 2, and a medium inlet 23 and a medium outlet 24 are respectively provided on the opposite sides of the kettle body 2, and the medium inlet 23 and the medium outlet 24 are both connected to the heat exchange chamber. In actual use, hot water can be injected into the heat exchange chamber to heat or keep the solution in the solution chamber 21 warm.

[0045] In addition, in this embodiment, a feeding pipe 221 is provided on the sealing cover 22, and a discharging pipe 25 is provided on the lower side of the kettle body 2. The feeding pipe 221 and the discharging pipe 25 are both connected to the solution chamber 21, and gate valves or butterfly valves can be provided on the feeding pipe 221 and the discharging pipe 25 for opening and closing.

[0046] The implementation principle of the seawater fast-soluble salt-resistant polyacrylamide device of the embodiment of the present application is: in actual use, the solution to be polymerized is placed in the solution chamber 21, and hot water of the corresponding temperature can be injected into the heat exchange chamber to heat the solution to the required temperature, and nitrogen can be filled into the solution chamber 21 to adjust the pressure in the solution chamber 21.

[0047] During the polymerization reaction, the frequency conversion motor 31 drives the stirring shaft 32 to rotate. When the lift blade 321 rotates with the stirring shaft 32, the solution can be driven to move upward and rotate. At this time, the guide ridge 211 guides the outer solution to flow downward. At the same time, the obstruction plate 322 separates the middle solution and the outer solution in the solution chamber 21, reduces the interference between the movement of the middle solution and the outer solution, and ensures the stability of the circulation movement of the solution in the reactor 1.

[0048] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. Seawater fast-soluble salt-resistant polyacrylamide, characterized by: It includes the following components in mass ratio: polyacrylamide monomer 90-96%, co-solvent 4%-10%; The polyacrylamide monomer includes a carboxylic acid group.

2. The seawater-soluble salt-resistant polyacrylamide according to claim 1, characterized in that: The carboxylic acid group is introduced into the molecular chain of the polyacrylamide monomer by copolymerization.

3. The seawater-soluble salt-resistant polyacrylamide according to claim 1, characterized in that: The co-solvent is urea and / or formamide.

4. The preparation process of the seawater-soluble salt-resistant polyacrylamide according to any one of claims 1 to 3, characterized in that: The steps include: mixing acrylamide monomer with acrylic acid to form a mixed solution; adding an initiator to the mixture; Performing a polymerization reaction on the mixed solution to which the initiator is added, thereby obtaining a polymer solution; Drying the polymer solution and granulating the dried polymer solution to form polyacrylamide particles; The preparation is completed by mixing the polyacrylamide particles and the co-solvent.

5. The process for preparing the seawater-soluble salt-resistant polyacrylamide according to claim 4, characterized in that: The initiator is ammonium persulfate.

6. The process for preparing the seawater-soluble salt-resistant polyacrylamide according to claim 4, characterized in that: The temperature of the polymerization reaction is controlled between 50-65 degrees Celsius; the pressure of the polymerization reaction is controlled between 0.1-0.5MPa.

7. The process for preparing the seawater-soluble salt-resistant polyacrylamide according to claim 4, characterized in that: Before adding the initiator, sodium hydroxide solution is added to the mixed solution to adjust the pH value of the mixed solution to [6-7].

8. The process for preparing the seawater-soluble salt-resistant polyacrylamide according to claim 4, characterized in that: During the polymerization reaction, the mixture is continuously stirred.

9. A device for preparing seawater-soluble salt-resistant polyacrylamide, used for the polymerization reaction in the process for preparing seawater-soluble salt-resistant polyacrylamide according to any one of claims 4 to 8, characterized in that: The reactor (1) comprises a reactor body (2), a solution cavity (21) being formed in the reactor body (2), a sealing cover (22) being arranged on the upper side of the reactor body (2), a stirring shaft (32) being rotatably arranged on the sealing cover (22), the stirring shaft (32) being arranged downward and extending into the reactor body (2), a lift blade (321) being fixed on the stirring shaft (32), one side of the lift blade (321) being close to the stirring shaft (32) and being fixed to the stirring shaft (32), the other side of the lift blade (321) extending towards a side away from the stirring shaft (32), the lift blade (321) being located in the reactor body (2), and the lift blade (321) being arranged obliquely upward; A guide ridge (211) is fixed on the inner wall of the reaction kettle (1); the guide ridge (211) surrounds the reaction kettle (1) and is in a spiral shape.

10. The device for preparing seawater fast-soluble salt-resistant polyacrylamide according to claim 9, characterized in that: A blocking plate (322) is provided on the side of the lift blade (321) facing away from the stirring shaft (32), and the blocking plate (322) is provided along the inclination direction of the lift blade (321).

Images