Composite water control agent and application thereof

Abstract

The invention relates to a composite water control agent and application thereof. The composite water control agent comprises a polymeric monomer, nano silicon dioxide, an emulsifier, an initiator and water. Wherein the polymeric monomers are acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido tetradecane sulfonic acid and a surface and interface modified monomer; and the surface and interface modification type monomer is 3-methacryloyloxypropyltriethoxysilane.

Description

Technical Field

[0001] This invention belongs to the field of enhanced oil recovery technology in oilfield chemistry, and particularly relates to composite water control agents and their applications. Background Technology

[0002] In oil and gas extraction, the water control principle of selective water shut-off agents mainly relies on the different flow resistances they create when encountering oil and water in the formation, thus achieving selective water control. Selective water shut-off agents are primarily long-chain polymer molecules. By extending their long chains in the aqueous phase and contracting them in the oil phase, they alter the pore size in the formation, increasing the flow resistance of the aqueous phase and decreasing the flow resistance of the oil phase. Because selective water shut-off agents do not physically block the pore volume, they produce a relatively good selective water shut-off effect. Currently, common selective water shut-off agents have a relatively weak ability to affect the flow of oil and water phases. Furthermore, the adsorption of common selective water shut-off agents on the surface of reservoir sandstone is generally weak, such as electrostatic adsorption and hydrogen bonding, making them easily eroded by formation water flow. After multilayer adsorption, the adsorption force of ordinary selective water shut-off agents becomes even weaker, making them very easy to peel off from the sandstone surface, thus affecting the effective period of the shut-off agent. Their temperature and salt resistance also have certain problems. Summary of the Invention

[0003] In view of the shortcomings and deficiencies of current reservoir water control agents, this invention provides a composite water control agent.

[0004] The composite water-controlling agent of this invention adheres more firmly to the sandstone surface, making it less susceptible to erosion and extending its effective period. The added hydrophilic modified nano-silica significantly reduces the water phase permeability of the reservoir, providing a highly efficient and long-lasting selective water-blocking effect.

[0005] One aspect of the present invention provides a composite water-controlling agent comprising a polymeric monomer, nano-silica, an emulsifier, an initiator, and water.

[0006] In one specific embodiment, the polymerizing monomer is acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamidotetradecanesulfonic acid, and surface-modifying monomers.

[0007] In one specific embodiment, the molar ratio of acrylic acid, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-tetradecanesulfonic acid and the surface-modified monomer is (2-4):(2-4):(1-3):(1-3):(0.5-1.5).

[0008] In one specific embodiment, the interface-modifying monomer is 3-methacryloyloxypropyltriethoxysilane.

[0009] In one specific embodiment, the nano-silica is hydrophilic modified nano-silica, which is prepared by hydrophilic modification of nano-silica with 3-mercaptopropylmethyldiethoxysilane and hydrogen peroxide.

[0010] In one specific embodiment, the emulsifier is a complex formed by Tween-80 and sodium dodecyl sulfate in a 1:1 mass ratio.

[0011] In one specific embodiment, the initiator is ammonium persulfate.

[0012] In one specific embodiment, based on the total mass of the composite water-controlling agent as 100%, the total mass of the polymeric monomers accounts for 28% to 35%; the mass of the nano-silica accounts for 0.5% to 1.2%; the mass of the emulsifier accounts for 0.8% to 1.2%; and the mass of the initiator accounts for 0.5% to 1.2%.

[0013] In one specific embodiment, the total mass of the composite water-controlling agent is taken as 100%, and the total mass of the polymeric monomers accounts for 30% to 32%.

[0014] The second invention provides the application of the composite water-controlling agent according to any one of the first inventions in water shut-off in oil reservoirs, especially in water shut-off in high-temperature and high-salinity oil reservoirs.

[0015] In one specific embodiment, the application should be in water shut-off in high-temperature, high-salinity oil reservoirs. The maximum high temperature is 180°C; the maximum salinity is 250,000 mg / L.

[0016] The beneficial effects of this invention are:

[0017] The composite water-controlling agent of this invention modifies the rock surface with superhydrophilicity and forms a micro-nano dual-scale rough structure with micron-scale pores, thereby increasing the surface roughness of the rock and realizing the superhydrophilic (superwetting) effect on the rock surface.

[0018] The present invention exhibits stronger adhesion to sandstone surfaces, making it less susceptible to erosion and extending its effective period. The hydrophilic modified nano-silica and micron-level pores form a dual-scale rough structure, achieving superhydrophilic modification of the rock surface. Combined with the synergistic effect of the copolymer's own oil-water selectivity regulation, this significantly enhances the selective water-blocking effect of the composite water-controlling agent.

[0019] The composite water-controlling agent of the present invention enhances the oil-water selectivity and improves the ability to pass through the oil phase.

[0020] The composite water-controlling agent of this invention has greatly improved temperature and salt resistance, making it more suitable for harsh (high temperature and high salt) oil reservoirs.

[0021] The present invention relates to a super-wetting, temperature-resistant, and salt-resistant surface-modified selective composite water-controlling agent. The hydrophilic modified nano-silica is electrostatically adsorbed onto the surface of rock pores, forming a micro-nano dual-scale rough structure with micron-scale pores, which increases the surface roughness of the rock, realizes the super-hydrophilic effect on the rock surface, and improves the blocking rate of the aqueous phase. Attached Figure Description

[0022] Figure 1 It shows AA, AM, AMPS, and AMC. 14 Structural characterization of S.

[0023] Figure 2 The structural characterization of the composite water-controlling agent and 3-methacryloyloxypropyltriethoxysilane is shown.

[0024] Figure 3 The results of thermogravimetric analysis (TG) of the composite water-controlling agent of Example 1 are shown. Detailed Implementation

[0025] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0026] To characterize the molecular structure of the composite water-controlling agent of the present invention, infrared spectroscopy was used to study AA, AM, AMPS, and AMC. 14 The structures of four monomers, 3-methacryloyloxypropyltriethoxysilane, and the composite water-controlling agent were characterized, and the results are shown in the figure. Figure 1 and Figure 2 .

[0027] The thermal stability of the composite water-controlling agent in Example 1 was tested using a thermogravimetric analyzer. The results are shown in [Figure 1]. Figure 3 .

[0028] The selective water control performance of the composite water control agent was evaluated in the laboratory using displacement and erosion resistance tests.

[0029] Displacement experiment steps: (1) Fill the sand-filled pipe (inner diameter 2.52cm, length 30cm) with 200 mesh quartz sand, vacuum and saturate the sand-filled pipe with water, calculate the pore volume and porosity, and displace 250000mg / L mineralization simulated formation water and kerosene into the sand-filled pipe respectively, and record the water phase permeability and oil phase permeability before the sand-filled pipe is plugged. (2) Inject 2PV (PV refers to pore volume) of composite water control agent, age it at 180℃ for 8h, and displace 4PV of brine and 4PV of kerosene in reverse respectively, and record the water phase permeability and oil phase permeability after the sand-filled pipe is plugged.

[0030] The sealing rates of the aqueous and oil phases before and after the injection of the composite water-controlling agent are calculated using the formula.

[0031] Water phase plugging rate formula: R fw =k wa -k wb / k wa

[0032] In the formula: k wa — Aqueous phase permeability before injection of phase permeation conditioner; k wb — Aqueous phase permeability after injection of phase permeability regulator.

[0033] Oil phase plugging rate formula: R fo =k oa -k ob / k oa

[0034] In the formula: k oa —Oil phase permeability before injection of phase permeation regulator; k ob —Oil phase permeability after injection of phase permeation regulator.

[0035] Erosion resistance test procedure: The prepared composite water-controlling agent was diluted with 250,000 mg / L simulated formation water to form a composite aqueous solution with a mass fraction of 0.3%. A cleaned glass slide was dried and weighed (W0). It was then immersed in the composite water-controlling agent solution and allowed to stand for 24 hours. The slide was removed, dried, and weighed (W1). The slide was then rinsed for 1 hour, dried, and weighed (W2). The residual rate (R) reflects the erosion resistance of the composite water-controlling agent.

[0036] Formula for calculating residual rate R:

[0037] Example 1

[0038] The composite water-controlling agent and its preparation method in this embodiment include the following components by mass percentage: AA (acrylic acid), AM (acrylamide), AMPS (2-acrylamido-2-methylpropanesulfonic acid), and AMC. 14 The molar ratio of S (2-acrylamidotetradecanesulfonic acid) and the surface-modified monomer (3-methacryloyloxypropyltriethoxysilane) is 3:3:2:2:1, with the five monomers accounting for 28% of the total mass. The remaining components are: 0.5% hydrophilic modified nano-silica (hydrophilic modified nano-silica particles with an average particle size of 20 nm, purchased from Jingjiang Tonggao Chemical Co., Ltd.), 1.2% emulsifier (a 1:1 mixture of Tween-80 and sodium dodecyl sulfate), 1.2% initiator (ammonium persulfate), and water.

[0039] The preparation method of the composite water-controlling agent in this embodiment is as follows:

[0040] (1) AA, AM, AMPS and AMC 14S is prepared into an aqueous solution with a certain mass fraction, and an emulsifier and a surface-modifying monomer (3-methacryloyloxypropyltriethoxysilane) are added. After emulsification and dispersion, an emulsion is formed.

[0041] (2) Introduce N2 as a protective gas, keep the temperature constant at 40°C, add an initiator to the emulsion in step (1), and after reacting for 5 hours, add hydrophilic modified nano-silica to obtain the composite water control agent.

[0042] The results of the aqueous phase plugging rate and the oil phase plugging rate are shown in Table 1.

[0043] The results of the residual rate R are shown in Table 2.

[0044] Example 2

[0045] The composite water-controlling agent and its preparation method in this embodiment include the following components by mass percentage: AA, AM, AMPS, and AMC. 14 The molar ratio of S and the surface-modified monomer (3-methacryloyloxypropyltriethoxysilane) is 3:3:2:2:1, with the five monomers accounting for 30% of the total mass. The hydrophilic modified nano silica (hydrophilic modified nano silica particles with an average particle size of 20 nm, purchased from Jingjiang Tonggao Chemical Co., Ltd.) is 0.5%, the emulsifier (a mixture of Tween-80 and sodium dodecyl sulfate in a 1:1 ratio) is 1.2%, the initiator (ammonium persulfate) is 1.2%, and the remainder is water.

[0046] The preparation method of the composite water-controlling agent in this embodiment is as follows:

[0047] (1) AA, AM, AMPS and AMC 14 S is prepared into an aqueous solution with a certain mass fraction, and emulsifier and 3-methacryloyloxypropyltriethoxysilane are added. After emulsification and dispersion, an emulsion is formed.

[0048] (2) Introduce N2 as a protective gas, keep the temperature constant at 60°C, add an initiator to the emulsion in step (1), and after reacting for 7 hours, add hydrophilic modified nano-silica to obtain the composite water control agent.

[0049] The results of the aqueous phase plugging rate and the oil phase plugging rate are shown in Table 1.

[0050] The results of the residual rate R are shown in Table 2.

[0051] Example 3

[0052] The composite water-controlling agent and its preparation method in this embodiment include the following components by mass percentage: AA, AM, AMPS, and AMC. 14The molar ratio of S and the surface-modified monomer (3-methacryloyloxypropyltriethoxysilane) is 3:3:2:2:1. The five monomers account for 35% of the total mass. The hydrophilic modified nano silica (hydrophilic modified nano silica particles with an average particle size of 20 nm, purchased from Jingjiang Tonggao Chemical Co., Ltd.) is 0.5%, the emulsifier (Tween-80 and sodium dodecyl sulfate in a 1:1 ratio) is 1.2%, the initiator (ammonium persulfate) is 1.2%, and the remainder is water.

[0053] The preparation method of the composite water-controlling agent in this embodiment is as follows:

[0054] (1) AA, AM, AMPS and AMC 14 S is prepared into an aqueous solution with a certain mass fraction, and an emulsifier and a reactive monomer (3-methacryloyloxypropyltriethoxysilane) are added. After emulsification and dispersion, an emulsion is formed.

[0055] (2) Introduce N2 as a protective gas, keep the temperature constant at 55°C, add an initiator to the emulsion in step (1), and after reacting for 5 hours, add hydrophilic modified nano-silica to obtain the composite water control agent.

[0056] The results of the aqueous phase plugging rate and the oil phase plugging rate are shown in Table 1.

[0057] The results of the residual rate R are shown in Table 2.

[0058] Example 4

[0059] The composite water-controlling agent and its preparation method in this embodiment include the following components by mass percentage: AA, AM, AMPS, and AMC. 14 The molar ratio of S and the surface-modified monomer (3-methacryloyloxypropyltriethoxysilane) is 3:3:2:2:1. The five monomers account for 30% of the total mass. The hydrophilic modified nano silica (hydrophilic modified nano silica particles with an average particle size of 20 nm, purchased from Jingjiang Tonggao Chemical Co., Ltd.) is 1.0%, the emulsifier (Tween-80 and sodium dodecyl sulfate in a 1:1 ratio) is 1.2%, the initiator (ammonium persulfate) is 1.2%, and the remainder is water.

[0060] The preparation method of the composite water-controlling agent in this embodiment is as follows:

[0061] (1) AA, AM, AMPS and AMC 14 S is prepared into an aqueous solution with a certain mass fraction, and an emulsifier and a reactive monomer (3-methacryloyloxypropyltriethoxysilane) are added. After emulsification and dispersion, an emulsion is formed.

[0062] (2) Introduce N2 as a protective gas, keep the temperature constant at 55°C, add an initiator to the emulsion in step (1), and after reacting for 5 hours, add hydrophilic modified nano-silica to obtain the composite water control agent.

[0063] The results of the aqueous phase plugging rate and the oil phase plugging rate are shown in Table 1.

[0064] The results of the residual rate R are shown in Table 2.

[0065] Example 5

[0066] The composite water-controlling agent and its preparation method in this embodiment include the following components by mass percentage: AA, AM, AMPS, and AMC. 14 The molar ratio of S and the surface-modified monomer (3-methacryloyloxypropyltriethoxysilane) is 3:3:2:2:1. The five monomers account for 30% of the total mass. The hydrophilic modified nano silica (hydrophilic modified nano silica particles with an average particle size of 20 nm, purchased from Jingjiang Tonggao Chemical Co., Ltd.) is 1.2%, the emulsifier (Tween-80 and sodium dodecyl sulfate in a 1:1 ratio) is 1.2%, the initiator (ammonium persulfate) is 1.2%, and the remainder is water.

[0067] The preparation method of the composite water-controlling agent in this embodiment is as follows:

[0068] (1) AA, AM, AMPS and AMC 14 S is prepared into an aqueous solution with a certain mass fraction, and emulsifier and 3-methacryloyloxypropyltriethoxysilane are added. After emulsification and dispersion, an emulsion is formed.

[0069] (2) Introduce N2 as a protective gas, keep the temperature constant at 55°C, add an initiator to the emulsion in step (1), and after reacting for 5 hours, the composite water control agent can be obtained.

[0070] The results of the aqueous phase plugging rate and the oil phase plugging rate are shown in Table 1.

[0071] The results of the residual rate R are shown in Table 2.

[0072] Example 6

[0073] The difference from Examples 4 and 5 is that the composition does not contain hydrophilic modified nano-silica, and includes the following composition by mass percentage: 30% of surface-modified monomer (3-methacryloyloxypropyltriethoxysilane), 1.2% of emulsifier (Tween-80 and sodium dodecyl sulfate in a 1:1 ratio), 1.2% of initiator (ammonium persulfate), and the remainder is water.

[0074] The preparation method of the water-controlling agent in this embodiment is as follows:

[0075] (1) Prepare an aqueous solution of 3-methacryloyloxypropyltriethoxysilane with a certain mass fraction, and add an emulsifier to emulsify and disperse to form an emulsion.

[0076] (2) Introduce N2 as a protective gas, keep the temperature constant at 55°C, add an initiator to the emulsion in step (1), and after reacting for 5 hours, add hydrophilic modified nano-silica to obtain the composite water control agent.

[0077] The results of the aqueous phase plugging rate and the oil phase plugging rate are shown in Table 1.

[0078] The results of the residual rate R are shown in Table 2.

[0079] Table 1

[0080] Example Aqueous phase blocking rate Oil phase plugging rate Example 1 92.5％ 14.9％ Example 2 94.3％ 14.6％ Example 3 95.3％ 13.8％ Example 4 94.5％ 14.5％ Example 5 94.7％ 14.1％ Example 6 71.3％ 30.2％

[0081] As shown in Table 1, the agents synthesized in Examples 1 to 4 exhibit excellent plugging performance, with their aqueous solutions achieving a plugging rate of over 90%. Examples 2, 4, 5, and 6 demonstrate a synergistic effect between the copolymer and the nano-modified silica. The agents synthesized in Examples 1 to 5 effectively plug core pores, significantly reducing the aqueous permeability of the core, while exhibiting minimal plugging effect on the oil phase. This indicates that the synthesized superwetting, temperature-resistant, and salt-resistant surface-modified selective composite water control agent possesses excellent oil-water selectivity, enabling deep regulation and displacement in oilfields.

[0082] Table 2

[0083] Example <![CDATA[W0 / g]]> <![CDATA[W1 / g]]> <![CDATA[W2 / g]]> Residual rate R / % Example 1 5.1038 5.1054 5.1051 81.2 Example 2 5.1125 5.1140 5.1137 80.0 Example 3 5.1224 5.1244 5.1241 85.0 Example 4 5.1124 5.1141 5.1138 82.3 Example 5 5.1024 5.1036 5.1034 83.3 Example 6 5.1035 5.1042 5.1039 57.1

[0084] As can be seen from Table 2, the residual rate of the agents synthesized in Examples 1 to 5 is still above 80% after rinsing, indicating that the composite water control agent is more firmly adsorbed on the sandstone surface, is difficult to be rinsed, and has a longer effective period.

[0085] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A composite water shutoff agent, comprising a polymerized monomer, nano-silica, an emulsifier, an initiator and water.

2. The composite water control agent according to claim 1, characterized by The polymerized monomer is acrylic acid, acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, 2-acrylamidotetradecane sulfonic acid and a surface interface modification monomer.

3. The composite water control agent according to claim 2, characterized in that, The molar ratio of the acrylic acid, acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, 2-acrylamidotetradecane sulfonic acid and the surface interface modification monomer is (2-4) : (2-4) : (1-3) : (1-3) : (0.5-1.5).

4. The composite water control agent according to claim 1, characterized by, The surface interface modification monomer is 3-methacryloyloxypropyl triethoxysilane.

5. The composite water control agent according to claim 1, characterized in that, The nano-silica is hydrophilic modified nano-silica, which is prepared by hydrophilic modification of nano-silica with 3-mercaptopropylmethyldiethoxysilane and hydrogen peroxide.

6. The composite water control agent according to claim 1, characterized by, The emulsifier is a complex of Tween-80 and sodium dodecyl sulfate in a mass ratio of 1:

1.

7. The composite water control agent according to claim 1, characterized by, The initiator is ammonium persulfate.

8. The composite water control agent according to claim 1, characterized by, The total mass of the polymerized monomer accounts for 28% to 35%, the mass of the nano-silica accounts for 0.5% to 1.2%, the mass of the emulsifier accounts for 0.8% to 1.2% and the mass of the initiator accounts for 0.5% to 1.2%, based on the total mass of the composite water shutoff agent as 100%.

9. The composite water control agent according to claim 8, characterized in that, The total mass of the polymerized monomer accounts for 30% to 32%, based on the total mass of the composite water shutoff agent as 100%. 10.The composite water shutoff agent according to any one of claims 1 to 9 is used in water shutoff of an oil reservoir, in particular, in water shutoff of a high-temperature and high-salt oil reservoir.

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