Copolymer for inhibiting sand by utilizing charge effect and preparation method thereof

Abstract

The invention discloses a copolymer for inhibiting sand by utilizing charge effect, which comprises the following components in parts by mass: 20 parts of vinylpyridine; 35 parts of styrene; 35 parts of butyl acrylate; 10 parts of a coupling agent; 0.1 to 0.3 part of an initiator; the sand-inhibiting copolymer is suitable for the technical field of chemical sand prevention, the prepared sand-inhibiting copolymer is prepared by utilizing tetrahydrofuran and is easy to inject, the polarity of a system is changed when the sand-inhibiting copolymer encounters water after the sand-inhibiting copolymer enters a stratum, and the precipitation rate of an oil-soluble polymer is controlled by utilizing the change of the polarity of the solvent of the system; the separated oil-soluble polymer can be filled among sand grains, the adhesion to the sand grains is enhanced by utilizing chemical bonding and physical binding effects, meanwhile, the adhesion among the sand grains is enhanced by utilizing the charge effect, the sand suppression effect is obvious, the operation is simple, the injection cost is obviously reduced, and the industrial application is easy.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical sand control, and specifically relates to a sand control copolymer using charge interaction and a preparation method thereof. Background Art

[0002] Due to factors such as reservoir geological conditions and oil and gas production, sand production is serious. Sand production in oil wells can lead to high production costs and even well plugging. Nowadays, oilfield sand control methods are mainly divided into mechanical sand control and chemical sand control. Chemical sand control is to cement loose sand and gravel with a bonding chemical reagent to solve the problem of formation sand production.

[0003] According to Zhan Ningning et al.'s "Review of Oilfield Chemical Sand Control Technology", traditional oil and gas well chemical sand control is mainly a resin consolidated sand system, which can be divided into phenolic resin sand control. This type of sand control agent is suitable for formations with low sand production and low clay content, and is not suitable for long-term water injection development; urea formaldehyde resin sand control, with low price and suitable for sand-producing oil wells during the high water cut period, but the bonding between this resin and sand grains is not firm; modified epoxy resin sand control, this resin is suitable for medium and low temperature reservoirs; and resin sand control agents have large molecular weights and high viscosities, seriously affecting the pumpability of the sand control system into the formation, with a short sand control period and being basically not applicable to formations with large permeability differences.

[0004] With the increasing requirements for sand control technology and effect, there is an urgent need to develop a sand control agent that utilizes charge attraction, has good sand control effect, long cycle, and is easy to inject for reservoirs with the characteristics of sandstone potential. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a sand control copolymer using charge interaction and a preparation method thereof.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect, a sand control copolymer using charge interaction, its structural formula is:

[0008]

[0009] Preferably, by mass fraction, it includes the following components:

[0010] 20 parts of vinylpyridine;

[0011] 35 parts of styrene;

[0012] 35 parts of butyl acrylate;

[0013] 10 parts of coupling agent;

[0014] 0.1 - 0.3 parts of initiator;

[0015] 150 parts of solvent.

[0016] Preferably, the coupling agent is γ-methacryloxypropyltrimethoxysilane.

[0017] Preferably, the initiator is azobisisobutyronitrile.

[0018] Preferably, the solvent is tetrahydrofuran.

[0019] In a second aspect, a method for preparing a charge-action sand control copolymer includes the following steps:

[0020] S1 Weigh the formulated amounts of vinylpyridine, styrene, butyl acrylate, coupling agent, initiator and solvent into a reaction vessel, heat to a certain temperature for reflux until the reaction ends;

[0021] S2 Filter the prepared polymer while it is hot, and after the filtrate is cooled to a certain temperature, perform vacuum filtration;

[0022] S3 Dissolve the precipitated substance in ethanol, raise the temperature to a certain temperature, and perform vacuum filtration;

[0023] S4 Repeat step S3 several times to obtain a weak cationic copolymer sand control agent.

[0024] Preferably, in step S1, the reaction vessel is a three-necked flask.

[0025] Preferably, in step S1, the reaction temperature is 70-80 °C and the reaction time is 6-8 h.

[0026] Preferably, in step S1, a constant temperature oil bath is used for heating.

[0027] Preferably, in step S1, nitrogen is introduced for protection before heating.

[0028] Preferably, in step S2, after the filtrate is cooled to 25 °C, vacuum filtration is performed.

[0029] Preferably, in step S3, the temperature is raised to 70-80 °C and vacuum filtration is performed.

[0030] Preferably, in step S4, step S3 is repeated three times.

[0031] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0032] In the present invention, the prepared sand control copolymer is easily injectable by being formulated with tetrahydrofuran. When it enters the formation and encounters water, the system polarity changes. By using the change in the polarity of the system solvent, the precipitation rate of the oil-soluble polymer is controlled. The precipitated oil-soluble polymer can fill the spaces between sand grains, and the adhesion ability to sand grains is strengthened by chemical bonding and physical binding effects. At the same time, the adhesion between sand grains is enhanced by charge effects. The sand control effect is obvious, the operation is simple, the injection cost is significantly reduced, and it is easy to be applied industrially. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flowchart of a method for preparing a sand control copolymer using charge effects according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0034] The following examples are used to further illustrate the specific embodiments of a sand control copolymer using charge effects and its preparation method according to the present invention. The sand control copolymer using charge effects and its preparation method according to the present invention are not limited to the descriptions of the following examples.

[0035] Example 1:

[0036] A sand control copolymer using charge effects, its structural formula is:

[0037]

[0038] Furthermore, by mass fraction, it includes the following components:

[0039] 20 parts of vinylpyridine;

[0040] 35 parts of styrene;

[0041] 35 parts of butyl acrylate;

[0042] 10 parts of coupling agent;

[0043] 0.1 part of initiator;

[0044] 150 parts of solvent.

[0045] Furthermore, the coupling agent is γ-methacryloxypropyltrimethoxysilane.

[0046] Furthermore, the initiator is azobisisobutyronitrile.

[0047] Furthermore, the solvent is tetrahydrofuran.

[0048] Example 2:

[0049] A sand control copolymer using charge effects, by mass fraction, includes the following components:

[0050] 20 parts of vinylpyridine;

[0051] 35 parts of styrene;

[0052] 35 parts of butyl acrylate;

[0053] 10 parts of coupling agent;

[0054] 0.2 part of initiator;

[0055] 150 parts of solvent.

[0056] Example 3:

[0057] A sand control copolymer utilizing charge interaction, by mass fraction, includes the following components:

[0058] 20 parts of vinylpyridine;

[0059] 35 parts of styrene;

[0060] 35 parts of butyl acrylate;

[0061] 10 parts of coupling agent;

[0062] 0.3 part of initiator;

[0063] 150 parts of solvent.

[0064] Example 4:

[0065] A preparation method of a sand control copolymer utilizing charge interaction, as Figure 1 shown, includes the following steps:

[0066] S1 Weigh the formulated amounts of vinylpyridine, styrene, butyl acrylate, coupling agent, initiator and solvent into a reaction vessel, heat to a certain temperature for reflux until the reaction ends;

[0067] S2 Filter the prepared polymer while it is hot, and after the filtrate cools to a certain temperature, perform vacuum filtration;

[0068] S3 Dissolve the precipitated substance in ethanol, raise the temperature to a certain level, and perform vacuum filtration;

[0069] S4 Repeat step S3 several times to obtain a weak cationic copolymer sand control agent.

[0070] Furthermore, in step S1, the reaction vessel is a three-necked flask.

[0071] Furthermore, in step S1, the reaction temperature is 70 °C and the reaction time is 6 h.

[0072] Furthermore, in step S1, a constant temperature oil bath is used for heating.

[0073] Furthermore, in step S1, nitrogen is introduced for protection before heating.

[0074] Further, in step S2, after the filtrate is cooled to 25°C, it is filtered under reduced pressure.

[0075] Further, in step S3, the temperature is raised to 70°C and filtered under reduced pressure.

[0076] Further, in step S4, step S3 is repeated three times.

[0077] Example 5:

[0078] A preparation method of a sand control copolymer using charge interaction, other steps are similar to those in Example 4. Further, in step S1, the reaction temperature is 75°C and the reaction time is 7 h.

[0079] Further, in step S3, the temperature is raised to 75°C and filtered under reduced pressure.

[0080] Example 6:

[0081] A preparation method of a sand control copolymer using charge interaction, other steps are similar to those in Example 4. Further, in step S1, the reaction temperature is 80°C and the reaction time is 8 h.

[0082] Further, in step S3, the temperature is raised to 80°C and filtered under reduced pressure.

[0083] Example 7:

[0084] (1) Weigh 17.5 g of styrene, 10 g of vinylpyridine, and 17.5 g of butyl acrylate into a three-necked flask, add 0.05 g of azobisisobutyronitrile, 5 g of KH570, and 50 mL of tetrahydrofuran, protect with nitrogen, heat with a constant temperature oil bath, and reflux at 70°C for 6 h;

[0085] (2) Filter the prepared polymer while it is hot. After the filtrate is cooled to room temperature, filter it under reduced pressure; dissolve the precipitated substance in ethanol, raise the temperature to 80°C, and filter it under reduced pressure. Repeat the above steps 3 times to obtain a weak cationic sand control agent.

[0086] Prepare polymer solutions with different concentrations using tetrahydrofuran for performance measurement.

[0087] Example 8:

[0088] (1) Weigh 17.5 g of styrene, 10 g of vinylpyridine, and 17.5 g of butyl acrylate into a three-necked flask, add 0.07 g of azobisisobutyronitrile, 5 g of KH570, and 75 mL of tetrahydrofuran, protect with nitrogen, heat with a constant temperature oil bath, and reflux at 75°C for 7 h;

[0089] (2) Filter the obtained polymer while hot, and after the filtrate is cooled to room temperature, filter it under reduced pressure; dissolve the precipitated substance in ethanol, raise the temperature to 80°C, and filter it under reduced pressure. Repeat the above steps 3 times to obtain a weak cationic sand inhibitor.

[0090] The polymer was prepared into solutions of different concentrations using tetrahydrofuran for performance testing.

[0091] Embodiment 9:

[0092] (1) Weigh 17.5 g of styrene, 10 g of vinyl pyridine and 17.5 g of butyl acrylate into a three-necked flask, add 0.1 g of azobisisobutyronitrile, 5 g of KH570 and 75 mL of tetrahydrofuran, pass nitrogen protection, heat in a constant temperature oil bath, and reflux at 80° C. for 8 h;

[0093] (2) Filter the obtained polymer while hot, and after the filtrate is cooled to room temperature, filter it under reduced pressure; dissolve the precipitated substance in ethanol, raise the temperature to 80°C, and filter it under reduced pressure. Repeat the above steps 3 times to obtain a weak cationic sand inhibitor.

[0094] The polymer was prepared into solutions of different concentrations using tetrahydrofuran for performance testing.

[0095] Embodiment 10:

[0096] (1) Weigh 35 g of styrene, 20 g of vinyl pyridine and 35 g of butyl acrylate into a three-necked flask, add 0.1 g of azobisisobutyronitrile, 10 g of KH570 and 150 mL of tetrahydrofuran, pass nitrogen protection, heat in a constant temperature oil bath, and reflux at 70°C for 7 h;

[0097] (2) Filter the obtained polymer while hot, and after the filtrate is cooled to room temperature, filter it under reduced pressure; dissolve the precipitated substance in ethanol, raise the temperature to 80°C, and filter it under reduced pressure. Repeat the above steps 3 times to obtain a weak cationic sand inhibitor.

[0098] The polymer was prepared into solutions of different concentrations using tetrahydrofuran for performance testing.

[0099] Embodiment 11:

[0100] (1) Weigh 35 g of styrene, 20 g of vinyl pyridine and 35 g of butyl acrylate into a three-necked flask, add 0.3 g of azobisisobutyronitrile, 10 g of KH570 and 150 mL of tetrahydrofuran, pass nitrogen protection, heat in a constant temperature oil bath, and reflux at 75°C for 8 h;

[0101] (2) Filter the obtained polymer while hot, and after the filtrate is cooled to room temperature, filter it under reduced pressure; dissolve the precipitated substance in ethanol, raise the temperature to 80°C, and filter it under reduced pressure. Repeat the above steps 3 times to obtain a weak cationic sand inhibitor.

[0102] Prepare polymer solutions with different concentrations using tetrahydrofuran for performance measurement.

[0103] Example 12:

[0104] (1) Weigh 35 g of styrene, 20 g of vinylpyridine, and 35 g of butyl acrylate into a three-necked flask, add 0.3 g of azobisisobutyronitrile, 10 g of KH570, and 150 mL of tetrahydrofuran. Protect with nitrogen, heat using a constant-temperature oil bath, and reflux at 80 °C for 8 h.

[0105] (2) Filter the prepared polymer while it is hot. After the filtrate cools to room temperature, perform vacuum filtration; dissolve the precipitated substance in ethanol, raise the temperature to 80 °C, and perform vacuum filtration. Repeat the above steps 3 times to obtain a weak cationic sand inhibitor.

[0106] Prepare polymer solutions with different concentrations using tetrahydrofuran for performance measurement.

[0107] The weak cationic sand inhibitor of the present invention is an oil-soluble polymer. The present invention uses common monomers of synthetic resin, styrene, vinylpyridine, and butyl acrylate, as monomers and coupling agent γ-methacryloxypropyltrimethoxysilane (KH570), and prepares through free radical polymerization reaction. The experimental conditions such as monomer ratio, initiator, and coupling agent are optimized to obtain a better process synthesis route. The anti-wind erosion and compressive properties of the sand inhibitor prepared in Example 12 are tested as follows:

[0108] (1) Research on anti-wind erosion performance

[0109] Filter the coarse sand with a sieve, select sand grains with a particle size between 0.3 mm and 0.45 mm, mix the sand grains and crude oil evenly at a mass ratio of 7:1, take 250 g of sand grains and add them evenly to a petri dish to obtain a sand pile model with consistent shape. Spray different concentrations of sand inhibitor onto the sand pile model at a spraying rate of 1 L / m 2 . After waiting for drying to form a consolidation layer, use an electric blower to simulate natural wind and blow the sand pile model from the front to see if the consolidation layer is damaged. Record the mass of the sand pile after half an hour. The results are shown in Table 1 below.

[0110] Table 1 Anti-wind erosion strength of sand inhibitor

[0111]

[0112] (2) Compressive properties

[0113] Filter the coarse sand with a sieve, select the sand grains with a particle size between 0.3 mm and 0.45 mm, mix the sand grains evenly with the crude oil at a mass ratio of 7:1, weigh 250 g of oil sand and mix it evenly with 20 g of sand inhibitor solution, add it to a mold with a height of 4.0 cm and a diameter of 7 cm, tamp it, and obtain a sand column model after drying. Put the prepared sand column model into a material mechanics testing machine for compression until the sand mold breaks, and the testing speed is 5 mm / min. The results are shown in Table 2 below.

[0114] Table 2 Compressive strength of sand inhibitor

[0115]

[0116] As shown above, with the increase in the mass concentration of the sand inhibitor, both the wind erosion resistance strength and the compressive strength are improved.

[0117] By adopting the above technical solutions:

[0118] An oil-soluble polymer sand inhibitor was prepared by emulsion copolymerization of vinylpyridine, styrene, and butyl acrylate. The monomer vinylpyridine in the polymer provides a weak cation, which can form a charge attraction with the polyhydroxy anions on the sandstone surface, thereby increasing the adhesion work between the sand inhibitor and the sandstone; styrene and butyl acrylate provide a hydrophobic structure, and butyl acrylate provides an alkyl structure, which can be incorporated into the oil film; at the same time, the coupling agent γ-methacryloxypropyltrimethoxysilane (KH-570) can strengthen the adhesion ability to sand grains. Using the solvent tetrahydrofuran to prepare a solution with a concentration of 10-20%, it is easy to inject into the formation, and then using water to dissolve into tetrahydrofuran to change the polarity of the solution, so that the polymer precipitates to fill the sand grains, thereby realizing effective sand control, and the operation is simple, significantly reducing the injection cost and facilitating industrial application.

[0119] To sum up, the present application has the following advantages:

[0120] (1) In the present application, a lipophilic polymer sand inhibitor with a weak cation is prepared by free radical polymerization using the common monomers styrene, vinylpyridine with weak cation characteristics, butyl acrylate providing an alkyl structure, and the coupling agent γ-methacryloxypropyltrimethoxysilane (KH570). The monomer vinylpyridine in the polymer provides a weak cation, which can form a charge attraction with the polyhydroxy anions on the sandstone surface, thereby increasing the adhesion work between the sand inhibitor and the sandstone; styrene and butyl acrylate provide a hydrophobic structure, and butyl acrylate provides an alkyl structure, which is easy to enter the oil film; KH-570 can strengthen the adhesion ability to sand grains. The reaction conditions of the experimental scheme are easy to control and the reaction process is simple;

[0121] (2) In this application, the copolymer with weak cationic properties can balance the negative charges on the sandstone surface and enhance the adhesion ability between particles. It avoids the mutual repulsion between its own colloidal particles caused by too high cation concentration in conventional sand control agents, and at the same time reduces the rock adsorption phenomenon of strong cationic polymers during injection.

[0122] (3) In this application, the prepared sand control copolymer is easy to inject by using tetrahydrofuran. When it enters the formation and encounters water, it changes the system polarity. By using the change of the system solvent polarity to control the precipitation rate of the oil-soluble polymer, the precipitated oil-soluble polymer can fill the space between sand grains, and strengthen the adhesion ability to sand grains by chemical bonding and physical binding. At the same time, the adhesion between sand grains is enhanced by charge interaction. The sand control effect is obvious, the operation is simple, and it is easy to be applied industrially.

[0123] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A sand control copolymer utilizing charge interaction, characterized in that, its structural formula is:

2. The sand control copolymer utilizing charge interaction according to claim 1, characterized in that, by mass fraction, it comprises the following components: 20 parts of vinylpyridine; 35 parts of styrene; 35 parts of butyl acrylate; 10 parts of coupling agent; 0.1 - 0.3 parts of initiator; 150 parts of solvent.

3. The sand control copolymer utilizing charge interaction according to claim 2, characterized in that, the coupling agent is γ-methacryloxypropyltrimethoxysilane.

4. The sand control copolymer utilizing charge interaction according to claim 2, characterized in that, the initiator is azobisisobutyronitrile.

5. The sand control copolymer utilizing charge interaction according to claim 2, characterized in that, the solvent is tetrahydrofuran.

6. A preparation method of a sand control copolymer utilizing charge interaction, characterized in that, it comprises the following steps: S1 Weigh the formulated amounts of vinylpyridine, styrene, butyl acrylate, coupling agent, initiator and solvent into a reaction vessel, heat to a certain temperature for reflux until the reaction ends; S2 Filter the prepared polymer while it is hot, and filter the prepared polymer while it is hot. After the filtrate is cooled to a certain temperature, carry out vacuum filtration; S3 Dissolve the precipitated substance in ethanol, raise the temperature to a certain temperature, and carry out vacuum filtration; S4 Repeat step S3 several times to obtain a weak cationic copolymer sand control agent.

7. The sand control copolymer utilizing charge interaction and its preparation method according to claim 6, characterized in that, in the step S1, the reaction vessel is a three-necked flask.

8. The sand control copolymer utilizing charge interaction and its preparation method according to claim 6, characterized in that, in the step S1, the reaction temperature is 70 - 80 °C, and the reaction time is 6 - 8 h.

9. The sand control copolymer utilizing charge interaction and its preparation method according to claim 6, characterized in that, in the step S1, a constant temperature oil bath is used for heating.

10. The sand control copolymer utilizing charge interaction and its preparation method according to claim 6, characterized in that, in the step S1, nitrogen is introduced for protection before heating.

11. The sand control copolymer utilizing charge interaction and its preparation method according to claim 6, characterized in that, in the step S2, after the filtrate is cooled to 25 °C, vacuum filtration is carried out.

12. The sand control copolymer utilizing charge interaction and its preparation method according to claim 6, characterized in that, in the step S3, the temperature is raised to 70 - 80 °C, and vacuum filtration is carried out.

13. The sand control copolymer utilizing charge interaction and its preparation method according to claim 6, characterized in that, in the step S4, step S3 is repeated three times.

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