A nano profile control agent for enhanced oil recovery and a preparation method thereof

Abstract

This invention specifically relates to a nano-adjusting agent for enhancing oil recovery and its preparation method. The adjusting agent of this invention consists of 0.1%–2.0% amphiphilic polymer, 0.1%–0.8% surfactant system, 0.5%–1.0% nanofiller, and 0.5%–3.0% retarder. The hydrophilic polymers are polyacrylamide, polyacrylic acid, and their copolymers, and the lipophilic polymer polystyrene; the surfactant system is a compound system consisting of a nonionic surfactant (fatty alcohol polyoxyethylene ether, EO number 12) and an anionic surfactant (sodium dodecylbenzenesulfonate); the nanofiller is amino-modified silica nanoparticles; and the retarder is polyether polyol and sorbitol. The results of the examples show that the adjusting agent has a high adsorption capacity on hydrophilic surfaces and a low adsorption capacity on lipophilic surfaces; it also has a high adsorption capacity on unsaturated oil core surfaces and a low adsorption capacity on saturated oil core surfaces, all indicating excellent selective adsorption properties.

Description

Technical Field

[0001] This invention belongs to the field of polymer compound composition technology, specifically relating to a nano-modified displacement agent for improving oil recovery and its preparation method. Background Technology

[0002] With the long-term water injection development of oilfields, the oilfields have gradually entered the medium-to-high water-cut stage, and high-permeability channels or large pores have gradually formed in the oil layers, further aggravating the heterogeneity of the reservoir and seriously affecting the effectiveness of waterflooding development. Modifiers play an important role in water control, production stabilization, and production enhancement measures in high-water-cut oilfields. Currently commonly used modifiers, such as polymer flooding, have disadvantages such as poor salt and temperature resistance, easy shear degradation during injection, and large viscosity loss; severe channeling in high-permeability layers, weak deep retention capacity, and difficulty in effectively sealing large pores and activating residual oil in low-permeability layers; gel / particle profile control agents are prone to wellhead blockage and cannot achieve deep migration; they also lack differentiated retention capacity, are non-selective for high and low permeability layers, and easily damage low-permeability reservoirs; surfactant flooding, when used alone, has insufficient mobility control, making it difficult to fully utilize oil washing efficiency, and is also costly.

[0003] The improved modifiers show some improvement in differentiated plugging and retention drag enhancement compared to traditional modifiers, but they still struggle to simultaneously meet core requirements such as injectability, deep migration, resistance to temperature, salt, and shear, and drag enhancement for oil displacement. Therefore, in order to achieve precise differentiated retention drag enhancement under different reservoir environments, it is urgent to develop new modifiers. Summary of the Invention

[0004] The purpose of this invention is to provide a nano-modifier for improving oil recovery and its preparation method. The modifier provided by this invention can form strong adsorption and retention on the surface of hydrophilic rocks, but no adsorption and retention on the surface of oleophilic rocks. By utilizing the difference in adsorption and retention, it selectively reduces the effective seepage diameter of pore throats in high water-cut areas of oil reservoirs and increases the seepage resistance in water areas, while not affecting the fluid seepage in high oil-cut areas. This achieves effective retention and resistance enhancement in high water-cut areas of oil reservoirs, expands the water drive sweep volume, and realizes water reduction and oil enhancement.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a differentiated retention drag-enhancing and flow-regulating agent. The amphiphilic polymer possesses both hydrophilic and lipophilic groups, forming a hydrophobic association network in water. It exhibits shear resistance, temperature resistance, and salt resistance, and can be adsorbed and retained in high-permeability layers, serving as the core for drag enhancement and flow rate control. The surfactant system reduces the oil-water interfacial tension and improves oil washing efficiency. Synergistically with the amphiphilic polymer, it forms supramolecular aggregates, enhancing system stability and transport capacity, and preventing near-wellbore crossflow. The nanofiller inhibits polymer degradation and can selectively embed into the pore throats of high-permeability layers, strengthening the retention drag-enhancing effect without clogging low-permeability layers. The slow-expansion system controls the expansion rate, avoiding excessive near-wellbore pressure and ensuring deep flow regulation effects.

[0007] A differentiated retention drag modulator comprises the following components by weight percentage:

[0008] Amphiphilic polymer systems: 0.1%~2.0%;

[0009] Surfactant system: 0.1%~0.8%;

[0010] Nanofiller 0.5%~1.0%;

[0011] Swelling retarder 0.5%~3.0%.

[0012] The preparation of the amphiphilic polymer system includes the following steps: the hydrophilic polymer is at least one of the following substances: polyacrylamide (PAM), polyacrylic acid (PAA), polyethylene glycol (PEG), carboxymethyl cellulose (CMC), 2-acrylamido-2-methylpropanesulfonic acid (AMPS) copolymer, acrylamide-acrylic acid copolymer, with a weight-average molecular weight of 1 million to 10 million; the lipophilic polymer is at least one of the following substances: polystyrene (PS), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), with a weight-average molecular weight of 10,000 to 400,000. S1, 0.5 to 1 part by weight of the hydrophilic polymer PAM is dissolved in 100 parts by weight of deionized water, stirred at 20 to 40°C for 4 hours, to prepare a PAM solution with a mass of 0.5% to 2%.

[0013] S1, a hydrophilic polymer is dissolved in deionized water and stirred at 20~40℃ for 4 hours to prepare a hydrophilic polymer solution with a mass of 0.5%~2%.

[0014] S2, dissolve the lipophilic polymer in an organic solvent, stir at 40~60℃ for 4h, add emulsifier and water, and emulsify at high speed of 6000rpm~10000rpm for 10~30min to prepare a nanoemulsion of the lipophilic polymer.

[0015] S3. The hydrophilic polymer solution prepared in S1 and the lipophilic nanoemulsion prepared in S2 are mixed with a crosslinking agent, protected by N2, and stirred at 40~60℃ for 6 hours to form an amphiphilic block polymer through the crosslinking agent.

[0016] S4. The amphiphilic block polymer prepared in S3 was precipitated with ethanol, centrifuged, and the precipitate was collected, dried at 60°C for 12 hours, pulverized and sieved to obtain the amphiphilic block polymer.

[0017] Preferably, the hydrophilic polymers are PAM and PAA; the lipophilic polymer is PS.

[0018] Preferably, the organic solvent is dichloromethane.

[0019] Preferably, the crosslinking agent is 0.5 to 1.5 parts by weight of N,N'-methylenebisacrylamide (MBA).

[0020] Preferably, the emulsifier comprises 4 parts by weight, namely Span-80 and Tween-80, wherein the mass ratio is 4:1.

[0021] The surfactant system is a compound system of nonionic surfactant and anionic surfactant with a mass ratio of 0.1 to 0.8 parts, wherein the nonionic surfactant is fatty alcohol polyoxyethylene ether (EO number of 12 to 18) and the anionic surfactant is sodium dodecylbenzenesulfonate, wherein the mass ratio is 1:0.5 to 3.

[0022] Preferably, the nonionic surfactant is a fatty alcohol polyoxyethylene ether (EO number 12).

[0023] The nanofiller is one of amino-modified silica nanoparticles, calcium carbonate, and molybdenum disulfide, with a particle size of 50~200nm.

[0024] Preferably, the nanofiller is amino-modified silica nanoparticles.

[0025] The slow-swelling agent is one of polyether polyol, polyether amine, glycerol, and sorbitol.

[0026] Preferably, the retarder is a polyether polyol and sorbitol.

[0027] This invention also provides the application of the above-mentioned differentiated retention and resistance-enhancing agents in oil extraction.

[0028] Preferably, the application is the use of the modulating agent in the selective enhancement or plugging of oil reservoirs in high water-cut areas.

[0029] Beneficial effects:

[0030] (1) The modulator provided by the present invention adopts conventional polymer composite cross-linking method, the raw materials are readily available, the reservoir properties are widely applicable, and the injection performance is good.

[0031] (2) The temperature and salt resistance of the modulator provided by the present invention is good, and it can be prepared by using sewage or oilfield reinjection water.

[0032] (3) The modulator provided by the present invention has low adsorption and retention on the surface of oleophilic rocks, does not affect the oil phase flow channel, and achieves water blocking without oil blocking.

[0033] (4) The modulator provided by the present invention can selectively increase or block the water content of reservoirs in high water-cut areas, and has a significant effect on reducing water content and increasing oil production. Detailed Implementation

[0034] This invention provides a nano-scale enhanced oil recovery (EOR) modifier and its preparation method. In high water-cut regions, the hydrophilic segments of the amphiphilic polymer system form hydrogen bonds or electrostatic adsorption with the silanol groups (-SiOH) on the hydrophilic rock surface, causing the modifier to be firmly retained on the pore throat surface, reducing the effective flow diameter of the pore throat, and increasing the water phase flow resistance. In high oil-cut regions, the oleophilic segments of the amphiphilic polymer system have low affinity with the oil-wet surface, and the steric hindrance effect of the hydrophilic segments prevents the modifier from being adsorbed, keeping it in a free state and not affecting the oil phase flow. The surfactant system in the modifier system reduces the oil-water interfacial tension and improves oil washing efficiency; it synergistically forms supramolecular aggregates with the amphiphilic polymer, enhancing the system's stability and transport capacity, and preventing near-wellbore channeling; the nanofiller can inhibit polymer degradation and selectively embed into the pore throat of high-permeability layers, strengthening the retention and resistance-increasing effect without clogging low-permeability layers; the slow-expansion system controls the expansion rate, avoiding excessive near-wellbore pressure and ensuring the deep-level modifier effect.

[0035] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Unless otherwise specified, the production processes, experimental methods, or testing methods involved in the embodiments of this invention are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, which are very clear and distinct in the relevant application areas. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment, and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0037] The various instruments, equipment, raw materials or reagents used in the embodiments of this invention are not subject to any special restrictions on their source. They are all conventional products that can be purchased through regular commercial channels and can be prepared according to conventional methods known to those skilled in the art.

[0038] Example 1

[0039] 10.0 g of polyacrylamide with a molecular weight of 5 million was added to 1000 mL of deionized water and stirred at 30 °C for 4 h to dissolve, resulting in a 1.0% PAM aqueous solution.

[0040] 2.0 g of polystyrene (200,000 units) was dissolved in 20.0 mL of dichloroethane. The mixture was stirred at 50 °C for 4 h to dissolve. Then, 0.5 g of Span-80 and Tween-80 (mass ratio 4:1) were added, along with 4.0 mL of water. The mixture was then emulsified by high-speed shearing at 6000 rpm to obtain a PS emulsion.

[0041] A 1.0% PAM aqueous solution was mixed with a PS emulsion, and 0.15 g MBA was added. The mixture was then protected with N2 and stirred at 60 °C for 4 h. After cooling to room temperature, the mixture was precipitated with anhydrous ethanol, centrifuged, washed three times with deionized water, dried at 60 °C for 12 h, pulverized, and sieved to obtain the amphiphilic polymer.

[0042] 0.8 g of the above-mentioned amphiphilic polymer was dissolved in 98.7 g of formation water. The solution was stirred at 30°C and 1000 r / min until completely dissolved. Then, 0.3 g of fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate were added in a mass ratio of 1:2. The mixture was stirred at 40°C for 30 min to form a uniform dispersion. Finally, 0.5 g of amino-modified SiO2 nanofiller and 0.5 g of polyether polyol were added. This yielded product 1, a differentiated retention-enhancing and resistance-modifying agent.

[0043] Example 2

[0044] 10.0 g of polyacrylic acid with a molecular weight of 1 million was added to 1000 mL of deionized water and stirred at 30 °C for 4 h to dissolve, resulting in a 1.0% PAA aqueous solution.

[0045] 2.0 g of polystyrene (200,000 units) was dissolved in 20.0 mL of dichloroethane. The mixture was stirred at 50 °C for 4 h to dissolve. Then, 0.5 g of Span-80 and Tween-80 (mass ratio 4:1) were added, along with 4.0 mL of water. The mixture was then emulsified by high-speed shearing at 6000 rpm to obtain a PS emulsion.

[0046] A 1.0% PAA aqueous solution was mixed with a PS emulsion, and 0.15 g MBA was added. The mixture was then protected with N2 and stirred at 60°C for 4 h. After cooling to room temperature, the mixture was precipitated with anhydrous ethanol, centrifuged, washed three times with deionized water, dried at 60°C for 12 h, pulverized, and sieved to obtain the amphiphilic polymer.

[0047] 1.0 g of the above-mentioned amphiphilic polymer was dissolved in 97.5 g of formation water. The solution was stirred at 30°C and 1000 r / min until completely dissolved. Then, 0.5 g of fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate (mass ratio 1:2) were added, and the mixture was stirred at 40°C for 30 min to form a uniform dispersion system. Finally, 0.5 g of amino-modified SiO2 nanofiller and 0.5 g of sorbitol were added. This yielded product 2, a differentiated retention-enhancing and resistance-modifying agent.

[0048] Example 3

[0049] 10.0 g of polyacrylic acid with a molecular weight of 2 million was added to 1000 mL of deionized water and stirred at 30 °C for 4 h to dissolve, resulting in a 1.0% PAA aqueous solution.

[0050] 2.0 g of polystyrene (300,000 units) was dissolved in 20.0 mL of dichloroethane. The mixture was stirred at 50 °C for 4 h to dissolve. Then, 0.5 g of Span-80 and Tween-80 (mass ratio 4:1) were added, along with 4.0 mL of water. The mixture was then emulsified by high-speed shearing at 6000 rpm to obtain a PS emulsion.

[0051] A 1.0% PAA aqueous solution was mixed with a PS emulsion, and 0.15 g MBA was added. The mixture was then protected with N2 and stirred at 60°C for 4 h. After cooling to room temperature, the mixture was precipitated with anhydrous ethanol, centrifuged, washed three times with deionized water, dried at 60°C for 12 h, pulverized, and sieved to obtain the amphiphilic polymer.

[0052] 1.0 g of the above-mentioned amphiphilic polymer was dissolved in 96.5 g of formation water. The solution was stirred at 30°C and 1000 r / min until completely dissolved. Then, 0.5 g of fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate were added in a mass ratio of 1:2. The mixture was stirred at 40°C for 30 min to form a uniform dispersion. Finally, 1.0 g of amino-modified SiO2 nanofiller and 1.0 g of sorbitol were added. This yielded product 3, a differentiated retention-enhancing and resistance-modifying agent.

[0053] Example 4

[0054] Add 20.0g of polyacrylamide with a molecular weight of 10 million to 1000mL of deionized water and stir at 30℃ for 4h to dissolve, to obtain a 2.0% PAA aqueous solution.

[0055] 4.0 g of polystyrene (300,000 units) was dissolved in 20.0 mL of dichloroethane. The mixture was stirred at 50 °C for 4 h to dissolve. Then, 0.5 g of Span-80 and Tween-80 (mass ratio 4:1) were added, along with 4.0 mL of water. The mixture was then emulsified by high-speed shearing at 6000 rpm to obtain a PS emulsion.

[0056] A 2.0% PAM aqueous solution was mixed with a PS emulsion, and 0.15 g of MBA was added. The mixture was then purged with N2 under protection and stirred at 60°C for 4 h. After cooling to room temperature, the mixture was precipitated with anhydrous ethanol, centrifuged, washed three times with deionized water, dried at 60°C for 12 h, pulverized, and sieved to obtain the amphiphilic polymer.

[0057] 0.8 g of the above-mentioned amphiphilic polymer was dissolved in 98.7 g of formation water. The solution was stirred at 30°C and 1000 r / min until completely dissolved. Then, 0.3 g of fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate (mass ratio 1:2) were added. The mixture was stirred at 40°C for 30 min to form a uniform dispersion. Finally, 0.5 g of amino-modified SiO2 nanofiller and 0.5 g of polyether polyol were added. This yielded product 4, a differentiated retention-enhancing and resistance-modifying agent.

[0058] Example 5

[0059] Add 10.0g of the acrylamide and acrylic acid copolymer to 1000mL of deionized water and stir at 30℃ for 4h to dissolve, resulting in a 2.0% PAM-PAA aqueous solution.

[0060] 4.0 g of polystyrene (200,000 units) was dissolved in 20.0 mL of dichloroethane. The mixture was stirred at 50 °C for 4 h to dissolve. Then, 0.5 g of Span-80 and Tween-80 (mass ratio 4:1) were added, along with 4.0 mL of water. The mixture was then emulsified by high-speed shearing at 6000 rpm to obtain a PS emulsion.

[0061] A 1.0% aqueous solution of PAM-PAA was mixed with a PS emulsion, and 0.15 g of MBA was added. The mixture was then subjected to N2 protection and stirred at 60°C for 4 h. After cooling to room temperature, the mixture was precipitated with anhydrous ethanol, centrifuged, washed three times with deionized water, dried at 60°C for 12 h, pulverized, and sieved to obtain the amphiphilic polymer.

[0062] 1.0 g of the above amphiphilic polymer was dissolved in 97.5 g of formation water. The solution was stirred at 30°C and 1000 r / min until completely dissolved. Then, 0.5 g of fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate (mass ratio 1:2) were added. The mixture was stirred at 40°C for 30 min to form a uniform dispersion. Finally, 0.5 g of amino-modified SiO2 nanofiller and 0.5 g of sorbitol were added. This yielded product 5, a differentiated retention-enhancing and resistance-modifying agent.

[0063] Example 6

[0064] Add 20.0g of the acrylamide and acrylic acid copolymer to 1000mL of deionized water and stir at 30℃ for 4h to dissolve, resulting in a 2.0% PAM-PAA aqueous solution.

[0065] 4.0 g of polystyrene (300,000 units) was dissolved in 20.0 mL of dichloroethane. The mixture was stirred at 50 °C for 4 h to dissolve. Then, 0.5 g of Span-80 and Tween-80 (mass ratio 4:1) were added, along with 4.0 mL of water. The mixture was then emulsified by high-speed shearing at 6000 rpm to obtain a PS emulsion.

[0066] A 2.0% PAM-PAA aqueous solution was mixed with a PS emulsion, and 0.15 g of MBA was added. The mixture was then subjected to N2 protection and stirred at 60°C for 4 h. After cooling to room temperature, the mixture was precipitated with anhydrous ethanol, centrifuged, washed three times with deionized water, dried at 60°C for 12 h, pulverized, and sieved to obtain the amphiphilic polymer.

[0067] 1.0 g of the above amphiphilic polymer was dissolved in 96.5 g of formation water. The mixture was stirred at 30°C and 1000 r / min until completely dissolved. Then, 0.5 g of fatty alcohol polyoxyethylene ether and sodium dodecylbenzene sulfonate were added in a mass ratio of 1:2. The mixture was stirred at 40°C for 30 min to form a uniform dispersion. Finally, 1.0 g of amino-modified SiO2 nanofiller and 1.0 g of sorbitol were added. This yielded product 6, a differentiated retention-enhancing and resistance-modifying agent.

[0068] Comparative Example 1

[0069] 10.0 g of polyacrylamide with a molecular weight of 5 million was added to 1000 mL of deionized water and stirred at 30 °C for 4 h to dissolve, resulting in a 1.0% PAM aqueous solution.

[0070] 2.0 g of polystyrene (200,000 units) was dissolved in 20.0 mL of dichloroethane. The mixture was stirred at 50 °C for 4 h to dissolve. Then, 0.5 g of Span-80 and Tween-80 (mass ratio 4:1) were added, along with 4.0 mL of water. The mixture was then emulsified by high-speed shearing at 6000 rpm to obtain a PS emulsion.

[0071] A 1.0% PAM aqueous solution was mixed with a PS emulsion, and 0.15 g MBA was added. The mixture was then protected with N2 and stirred at 60 °C for 4 h. After cooling to room temperature, the mixture was precipitated with anhydrous ethanol, centrifuged, washed three times with deionized water, dried at 60 °C for 12 h, pulverized, and sieved to obtain the amphiphilic polymer.

[0072] 0.8 g of the above-mentioned amphiphilic polymer was dissolved in 98.7 g of formation water. The mixture was stirred at 30°C and 1000 r / min until completely dissolved. Then, 0.5 g of amino-modified SiO2 nanofiller and 0.5 g of polyether polyol were added to form a uniform dispersion system. A comparative product of differentiated retention-enhancing and resistance-modifying agents was obtained.

[0073] Test Example 1

[0074] To test the salt tolerance of different modulator products, a standard solution of modulator at 1000 mg / L was prepared using simulated formation water with different salinities. Several core samples with a length of 10 cm, a diameter of 2.5 cm, and a permeability of 140 mD were selected, saturated with simulated formation water after vacuuming, and then injected into the simulated formation water at a flow rate of 0.2 mL / min until the pressure stabilized. Subsequently, a 5 PV modulator solution was injected at a flow rate of 0.2 mL / min, and the injection pressure change of the modulator at the core inlet was monitored and recorded. Subsequent simulated formation water was then injected at a flow rate of 0.2 mL / min until the pressure stabilized. The plugging rate was calculated using Equation 1.

[0075] (1)

[0076] Wherein, η—blocking rate

[0077] ΔP0 — Water drive pressure difference (MPa)

[0078] ΔP2 — Subsequent water drive pressure difference (MPa)

[0079] As shown in Table 1, comparing the plugging test results of various embodiments under different simulated formation water salinity, it can be seen that when the salinity increases from 5000 mg / L to 20000 mg / L, the plugging rate of all embodiments decreases only slightly. In a high-salt environment of 20000 mg / L, the plugging rate of each group remains above 93%, proving that the plugging system has strong salt resistance and can stably perform its plugging function under high-salt conditions. Comparative Example 1 only shows good plugging effect in a low-salt environment of 5000 mg / L. The performance plugging rate decreases significantly after the salinity increases, indicating poor salt resistance. Compared with the problem that conventional plugging materials are prone to significant failure in high-salt environments, this system has obvious salt resistance advantages and can meet the field application requirements of high-salt reservoir regulation and flooding.

[0080] Table 1. Test results of plugging rate under different mineralization levels

[0081]

[0082] Test Example 2

[0083] To compare the temperature resistance of different modulator products, a standard solution of 1000 mg / L modulator was prepared using simulated formation water. Several core samples with a length of 10 cm, a diameter of 2.5 cm, and a permeability of 140 mD were selected, saturated with simulated formation water after vacuuming, and injected into the simulated formation water at different temperatures at a flow rate of 0.2 mL / min until the pressure stabilized. Subsequently, a 5 PV modulator solution was injected at different temperatures at a flow rate of 0.2 mL / min, and the injection pressure change at the core inlet was monitored and recorded. Subsequent simulated formation water was then injected at different temperatures at a flow rate of 0.2 mL / min until the pressure stabilized. The plugging rate was calculated using Equation 1.

[0084] Table 2 shows that, under the conditions of 45℃, 65℃, and 95℃, the plugging performance of each embodiment decreased slightly with increasing experimental temperature, with a relatively small overall decrease. At 95℃, the plugging rate of all embodiments remained above 93%, indicating that the plugging system has good high-temperature resistance and that increasing temperature does not significantly damage the plugging structure. Comparative Example 1 was significantly affected by temperature; the plugging effect continued to decline sharply with increasing temperature, reaching only 65.4% at 95℃, which is insufficient to meet plugging requirements at high temperatures.

[0085] Table 2. Test results of plugging rate at different temperatures

[0086]

[0087] Test Example 3: Static Adsorption Test

[0088] To test the differentiated adsorption performance of different revelocity modulators on hydrophilic and oleophilic surfaces, a 1000 mg / L standard solution of the revelocity modulator was prepared using simulated formation water. 5 g of hydrophilic and oleophilic quartz sand were weighed and placed in several conical flasks. Then, 50 mL of the revelocity modulator solution was added to each flask. The flasks were sealed and placed in a constant-temperature shaker at 120°C for 24 hours to ensure adsorption equilibrium was reached. After adsorption, the supernatant was centrifuged at high speed to obtain a clear supernatant. The adsorption capacity was calculated according to Equation 2, and the adsorption selectivity coefficient (Equation 3) was calculated based on the obtained adsorption capacity to evaluate the adsorption retention performance of the product.

[0089] (2)

[0090] Where Q represents the adsorption capacity (mg / L).

[0091] C o —Initial concentration (mg / L)

[0092] C e —Equilibrium concentration (mg / L)

[0093] V — Solution volume (L)

[0094] m — Mass of sand sample (g)

[0095] (3)

[0096] The results are shown in Table 3. The adsorption selectivity coefficients of Examples 1-6 show that the adsorption amount on the hydrophilic surface is higher and the adsorption amount on the lipophilic surface is lower, indicating that their selective adsorption is excellent. Comparison among the examples reveals that the molecular weight of polyacrylamide, the amount of surfactant added, the amount of nanofiller added, and the amount of retarder added are the key factors affecting the adsorption capacity of the differentiated retention-enhancing nano-modulator.

[0097] The larger the molecular weight of a hydrophilic polymer, the longer its molecular chain and the more polar adsorption sites it contains. This allows for stronger hydrogen bonding and electrostatic adsorption on hydrophilic rock surfaces, increasing the adsorption capacity. Conversely, on oleophilic surfaces, the increased steric hindrance of the polymer chains makes it difficult to overcome the oil film barrier, weakening hydrophobic association and reducing the adsorption capacity, thus further enhancing adsorption selectivity. Increasing the amount of surfactant improves the dispersion stability of the revetment agent in aqueous solution, reduces particle aggregation, and makes it easier for the active component to spread and adsorb on hydrophilic rock surfaces, increasing the hydrophilic adsorption capacity. Excess surfactant can create competitive adsorption at the oleophilic interface, weakening the interaction between the revetment agent and the oil film, further inhibiting oleophilic adsorption and improving adsorption selectivity. Increasing the amount of amino-modified SiO2 provides more physical adsorption interfaces and amino active sites, synergistically enhancing electrostatic adsorption and hydrogen bonding with the macromolecular chains, significantly improving the adsorption strength and capacity on hydrophilic surfaces. Since nanoparticles have difficulty penetrating the dense oil film on oleophilic surfaces, the oleophilic adsorption capacity is largely unaffected, thereby strengthening the differentiated adsorption and retention capacity of the revetment agent. Swelling retarders can regulate the swelling rate and degree of swelling of the repellent particles, preventing the adsorption layer from loosening and falling off due to excessive swelling of the particles, ensuring that the macromolecular chains and nanoparticles form a stable and dense adsorption layer on the hydrophilic rock surface, and enhancing the retention effect; the swelling retarders have poor compatibility with oil films, do not promote the adsorption on lipophilic surfaces, and do not affect the selective adsorption characteristics of the repellent.

[0098] Table 3 Static adsorption test results for different products

[0099]

[0100] Test Example 4: Dynamic Adsorption Test

[0101] To test the differentiated adsorption performance of different modulator products on hydrophilic and oleophilic surfaces, several core samples with a length of 10 cm, a diameter of 2.5 cm, and a permeability of 140 mD were selected and saturated with simulated formation water after vacuuming. Then, a portion of the core samples were saturated with oil. The saturated and unsaturated oil core samples were placed separately into a holder, and a confining pressure of 5 MPa was applied. Simulated formation water was injected at a flow rate of 0.2 mL / min until the pressure stabilized. Subsequently, the modulator solution was continuously injected at a flow rate of 0.2 mL / min, and the concentration change of the modulator at the core outlet was monitored and recorded. Injection continued until the outlet concentration (C) and the injected concentration (C0) were approximately equal, indicating that the core adsorption was saturated. The adsorption capacity was calculated using Equation 4, and the adsorption selectivity coefficient (Equation 5) was calculated based on the obtained adsorption capacity to evaluate the adsorption retention performance of the product.

[0102] (4)

[0103] Where Q represents the adsorption capacity (mg / g).

[0104] C o —Injection solution concentration (mg / mL)

[0105] V o —Total volume of injected modulator (mg)

[0106] —Total mass of aqueous phase flowing out during the experiment (mg)

[0107] (5)

[0108] The results are shown in Table 4. The adsorption capacity of unsaturated oil cores in Examples 1–6 was high, while that of saturated oil cores was low, with a significant difference between the two. The adsorption selectivity coefficients were all greater than 20, indicating that they all had excellent selective adsorption performance.

[0109] Increased hydrophilic molecular weight leads to longer macromolecular chains and more polar adsorption sites, resulting in stronger hydrogen bonds and electrostatic adsorption in the hydrophilic channels of unsaturated oil cores, significantly increasing dynamic adsorption capacity. However, on the surface of saturated oil cores, the steric hindrance effect of the polymer chains is enhanced, making it difficult to penetrate the dense oil film and overcome the oil-water interface resistance. Hydrophobic association is suppressed, further reducing adsorption capacity in saturated oil cores and increasing the dynamic selectivity coefficient. Increasing the amount of surfactant improves the dispersibility and flowability of the modulator in the aqueous phase, reducing particle aggregation and sedimentation during injection. This allows the active components to more easily enter the pores of unsaturated oil cores with the aqueous phase and be uniformly adsorbed, increasing dynamic adsorption capacity. Appropriate amounts of surfactant do not disrupt the stability of the oil film on the surface of saturated oil cores; instead, they further hinder the adhesion of the modulator to the oil phase interface through competitive adsorption, reducing adsorption capacity in saturated oil cores. Increasing the dosage of amino-modified SiO2 significantly increases the number of active sites on the surface of the modulator particles, synergistically enhancing physical adsorption and electrostatic interactions with the macromolecular chains. This results in a denser and more stable adsorption layer on the hydrophilic pore walls of unsaturated oil cores, enhancing dynamic retention. The small particle size and high polarity of the nanoparticles make it difficult for them to spread and adhere to the oleophilic surface of saturated oil cores, thus having almost no impact on the adsorption capacity of saturated oil cores. The retarder has poor compatibility with the oil phase and cannot form an effective adsorption-promoting effect on the surface of saturated oil cores, thus not weakening the dynamic selective adsorption characteristics of the modulator.

[0110] Table 4. Dynamic adsorption test results of different products

[0111]

[0112] As can be seen from the above embodiments, the modulator provided by the present invention has a high adsorption capacity on the hydrophilic surface and a low adsorption capacity on the oleophilic surface, that is, it has excellent selective adsorption. At the same time, the modulator provided by the present invention has a high adsorption capacity on the surface of unsaturated oil cores and a low adsorption capacity on the surface of saturated oil cores, with a large difference between the two. The adsorption selectivity coefficients are all greater than 25, which also indicates that it has excellent selective adsorption.

[0113] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A differentiated retention-enhancing and resistance-modifying agent, characterized in that, Includes the following components by weight percentage: Amphiphilic polymer systems: 0.1%~2.0%; Surfactant system: 0.1%~0.8%; Nanofiller 0.5%~1.0%; Swelling retarder 0.5%~3.0%.

2. The differentiated retention drag-increasing modulator according to claim 1, characterized in that: The amphiphilic polymer system is a block polymer of hydrophilic and lipophilic polymers; wherein the hydrophilic polymer is at least one of the following substances: polyacrylamide (PAM), polyacrylic acid (PAA), polyethylene glycol (PEG), carboxymethyl cellulose (CMC), 2-acrylamido-2-methylpropanesulfonic acid (AMPS) copolymer, acrylamide-acrylic acid copolymer, with a weight-average molecular weight of 1 million to 10 million; the lipophilic polymer is at least one of the following substances: polystyrene (PS), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), with a weight-average molecular weight of 10,000 to 400,000.

3. The differentiated retention drag-increasing modulator according to claim 2, characterized in that: The preparation of the amphiphilic polymer system includes the following steps: S1, a hydrophilic polymer is dissolved in deionized water and stirred at 20~40℃ for 4 hours to prepare a hydrophilic polymer solution with a mass of 0.5%~2%; S2, dissolve the lipophilic polymer in an organic solvent, stir at 40~60℃ for 4h, add emulsifier and water, and emulsify at high speed of 6000rpm~10000rpm for 10~30min to prepare a nanoemulsion of the lipophilic polymer. S3, the hydrophilic polymer solution prepared in S1 and the lipophilic nanoemulsion prepared in S2 are mixed with a crosslinking agent, protected by N2, and stirred at 40~60℃ for 6h, so that the hydrophilic polymer and the lipophilic polymer can form an amphiphilic block polymer through the crosslinking agent. S4. The amphiphilic block polymer prepared in S3 was precipitated with ethanol, centrifuged, and the precipitate was collected, dried at 60°C for 12 hours, pulverized and sieved to obtain the amphiphilic block polymer.

4. The modulator according to claim 3, characterized in that, In the preparation of the amphiphilic polymer system, the organic solvent is one of toluene, xylene, dichloromethane, and chloroform.

5. The modulator according to claim 3, characterized in that, In the preparation of the amphiphilic polymer system, the crosslinking agent is one of N,N'-methylenebisacrylamide (MBA) and glutaraldehyde, with a mass ratio of 0.5 to 1.5 parts.

6. The differentiated retention drag-increasing modulator according to claim 1, characterized in that: The surfactant system is a compound system of nonionic surfactant and anionic surfactant with a mass ratio of 0.1 to 0.8 parts, wherein the nonionic surfactant is fatty alcohol polyoxyethylene ether (EO number of 12 to 18) and the anionic surfactant is sodium dodecylbenzenesulfonate, wherein the mass ratio is 1:0.5 to 3.

7. The differentiated retention drag-increasing modulator according to claim 1, characterized in that: The nanofiller is one of amino-modified silica nanoparticles, calcium carbonate, and molybdenum disulfide, with a particle size of 50~200nm.

8. The differentiated retention drag-increasing modulator according to claim 1, characterized in that: The slow-swelling agent is one of polyether polyol, polyether amine, glycerol, and sorbitol.

9. The application of the modifier according to any one of claims 1-8 in oil extraction.

10. The application according to claim 9, characterized in that, The application refers to the use of modulating agents in the selective enhancement or plugging of oil reservoirs in high water-cut regions.

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