Nano-silicon-loaded phenolic resin reinforced jelly as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oilfield chemistry, and discloses nano-silicon-loaded phenolic resin reinforced jelly as well as a preparation method and application thereof. The method comprises the following steps: (1) mixing phenol and ethylenediamine according to a molar ratio of 1: (0.07-0.1), then adjusting the pH value to 8-10, then carrying out a first reaction on the obtained mixture, silane coupling agent modified silicon dioxide and a dispersion stabilizer at a first temperature, then cooling to a second temperature, and carrying out a second reaction to obtain a reaction solution I; (2) carrying out third reaction on the reaction solution I and a first formaldehyde solution to obtain a reaction solution II; and (3) carrying out fourth reaction on the reaction solution II and a second formaldehyde solution to obtain the nano-silicon loaded phenolic resin cross-linking agent. The nano-silicon-loaded phenolic resin reinforced jelly prepared by the method disclosed by the invention has obviously higher gelling strength and high-temperature-resistant stability.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, and in particular to a nano-silicon-loaded phenolic resin reinforced gel and a preparation method and application thereof. Background Art

[0002] As oilfield development enters the late stage, the overall recovery rate of conventional oil reservoirs has reached a high level, and further improving the recovery rate faces great challenges. Many conventional oilfields show significant reservoir permeability differences and serious heterogeneity problems. In addition, oilfields generally adopt water drive development, which causes water to advance rapidly in the reservoir along high permeability channels, forming water flow dominant channels, thereby exacerbating the heterogeneity of the reservoir. During the water drive process, the heterogeneity of the reservoir causes the water content of the production wells to increase rapidly, further reducing the development efficiency. Therefore, regulating and optimizing reservoir heterogeneity, especially in the process of water drive development, has become a key factor in improving crude oil recovery.

[0003] At present, phenolic resin integral gel is one of the most widely used plugging agents for oilfield profile control and water plugging at home and abroad. Its gelled liquid has low viscosity and is easy to inject. It can preferentially enter the dominant seepage channel of the formation. After being injected into the formation, it gradually solidifies into gel at the formation temperature, thereby blocking the water channel, improving the water drive sweep efficiency, and improving the crude oil recovery rate. Phenolic resin gel can be divided into direct phenolic resin gel and indirect phenolic resin gel. Direct phenolic resin gel usually uses a prepolymer obtained by polymerization of phenol and formaldehyde, which is then cross-linked with the polymer at a certain temperature to obtain a viscoelastic with a three-dimensional network structure, while indirect phenolic resin usually adds catechol, resorcinol and urotropine to the polymer to generate a spatial network viscoelastic in situ at a certain temperature. However, the gel prepared by direct phenolic resin has poor performance under the conditions of formation temperature and mineralization exceeding 90°C and 3×10 4 After the concentration of 100 mg / L, the gel strength and stability are greatly reduced, and it does not have the ability to block water channel for a long time. Therefore, strengthening the heat and salt resistance of direct phenolic resin by covalent grafting of nano-silicon materials is the key to effectively carry out oil reservoir water plugging, profile control operations and cost reduction and efficiency improvement. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem of low crude oil recovery rate caused by insufficient gel strength and high temperature stability of phenolic resin gel in the prior art, and to provide a nano-silicon-loaded phenolic resin reinforced gel and its preparation method and application. The nano-silicon-loaded phenolic resin reinforced gel prepared according to the method of the present invention has high gel strength and high temperature stability under high temperature and high salt conditions.

[0005] In order to achieve the above object, the present invention provides a method for preparing nano-silicon-loaded phenolic resin reinforced jelly, which comprises the following steps:

[0006] (1) mixing phenol and ethylenediamine at a molar ratio of 1:0.07-0.1, adjusting the pH value to 8-10, and then subjecting the obtained mixture to a first reaction with silica modified by a silane coupling agent and a dispersion stabilizer at a first temperature, and then cooling to a second temperature for a second reaction to obtain a reaction solution I;

[0007] (2) subjecting the reaction solution I to a third reaction with the first formaldehyde solution to obtain a reaction solution II;

[0008] (3) performing a fourth reaction on the reaction solution II and the second formaldehyde solution to obtain a nano-silicon-loaded phenolic resin cross-linking agent;

[0009] (4) polymerizing acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid at a molar ratio of 1:1.5-2:1.5-2 to obtain a functional polymer;

[0010] (5) mixing the functional polymer and water, and then mixing the obtained mixture with the nano-silicon-loaded phenolic resin cross-linking agent, and then aging at 90-130° C. to form a gel;

[0011] Wherein, the first temperature is 30-80°C higher than the second temperature;

[0012] The concentrations of the first formaldehyde solution and the second formaldehyde solution are the same, and are both 35-40% by weight. Taking the total amount of the first formaldehyde solution and the second formaldehyde solution as 100% by weight, the amount of the first formaldehyde solution is 70-80% by weight, and the amount of the second formaldehyde solution is 20-30% by weight.

[0013] Preferably, in step (1), the mass ratio of the silane coupling agent-modified silica to the total amount of the phenol and the ethylenediamine is 0.05-0.2:100.

[0014] Preferably, in step (1), the mass ratio of the dispersion stabilizer to the total amount of the phenol and the ethylenediamine is 0.05-0.15:100.

[0015] Preferably, in step (1), the first temperature is 140-160° C., the first reaction time is 2-3 h, the second temperature is 90-110° C., and the second reaction time is 6-8 h.

[0016] Preferably, the particle size of the silicon dioxide modified by the silane coupling agent is 1-200 nm.

[0017] Preferably, the dispersion stabilizer is at least one of silicate, polyethylene glycol and zwitterionic surfactant.

[0018] Preferably, in step (2), the conditions of the third reaction include: temperature of 60-80° C. and time of 1-2 h.

[0019] Preferably, in step (3), the conditions of the fourth reaction include: temperature of 75-95° C. and time of 1-2 h.

[0020] Preferably, in steps (1), (2) and (3), the molar ratio of the phenol to the formaldehyde in the first formaldehyde solution and the second formaldehyde solution is 1:2.5-3.

[0021] Preferably, the weight average molecular weight of the functional polymer is 8 million to 12 million.

[0022] Preferably, in step (5), the mass ratio of the functional polymer, the nano-silicon-loaded phenolic resin cross-linking agent and water is (0.2-0.6):(0.6-1.2):100.

[0023] The second aspect of the present invention provides a nano-silicon-loaded phenolic resin reinforced jelly prepared by the method described above.

[0024] The third aspect of the present invention provides the use of the nano-silicon loaded phenolic resin reinforced gel mentioned above in the process of recovering crude oil.

[0025] According to the preparation method of the nano-silicon-loaded phenolic resin reinforced gel of the present invention, nano-silicon dioxide is combined with phenolic resin by covalent grafting, the cross-linking density and cross-linking strength are improved, and the dehydration inhibition ability of the spatial network under high temperature and high salt conditions is enhanced. The prepared nano-silicon-loaded phenolic resin reinforced gel can have higher gel strength and high temperature stability under high temperature and high salt conditions, effectively improve reservoir heterogeneity, and improve crude oil recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the infrared spectrum of the nano-silicon-loaded phenolic resin cross-linking agent prepared in Example 1;

[0027] Figure 2 It is a pressure curve diagram of the plugging performance test of the nano-silicon loaded phenolic resin reinforced gel prepared in Example 1;

[0028] Figure 3 A diagram of a core displacement device for testing the plugging performance in the present invention;

[0029] Figure 4 This is a photo of the nano-silicon loaded phenolic resin jelly prepared in Example 1. DETAILED DESCRIPTION

[0030] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0031] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0032] The preparation method of the nano-silicon-loaded phenolic resin reinforced jelly of the present invention comprises the following steps:

[0033] (1) mixing phenol and ethylenediamine at a molar ratio of 1:0.07-0.1, adjusting the pH value to 8-10, and then subjecting the obtained mixture to a first reaction with silica modified by a silane coupling agent and a dispersion stabilizer at a first temperature, and then cooling to a second temperature for a second reaction to obtain a reaction solution I;

[0034] (2) subjecting the reaction solution I to a third reaction with the first formaldehyde solution to obtain a reaction solution II;

[0035] (3) performing a fourth reaction on the reaction solution II and the second formaldehyde solution to obtain a nano-silicon-loaded phenolic resin cross-linking agent;

[0036] (4) polymerizing acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid at a molar ratio of 1:1.5-2:1.5-2 to obtain a functional polymer;

[0037] (5) mixing the functional polymer and water, and then mixing the obtained mixture with the nano-silicon-loaded phenolic resin cross-linking agent, and then aging at 90-130° C. to form a gel;

[0038] Wherein, the first temperature is 30-80°C higher than the second temperature;

[0039] The concentrations of the first formaldehyde solution and the second formaldehyde solution are the same, and are both 35-40% by weight. Taking the total amount of the first formaldehyde solution and the second formaldehyde solution as 100% by weight, the amount of the first formaldehyde solution is 70-80% by weight, and the amount of the second formaldehyde solution is 20-30% by weight.

[0040] In step (1), preferably, the molar ratio of the phenol to the ethylenediamine is 1:0.07-0.1.

[0041] In step (1), the reagent for adjusting the pH value can be a sodium hydroxide solution and / or a hydrochloric acid solution. The mass concentration of the sodium hydroxide solution and the hydrochloric acid solution can each be 0.1-10wt%, preferably 0.5-5wt%, and more preferably 1-2wt%. In the most preferred embodiment, the reagent for adjusting the pH value is a sodium hydroxide solution. The process of adjusting the pH value can adjust the pH value of the reaction system to 8-10. In a preferred case, the process of adjusting the pH value adjusts the pH value of the reaction system to 8.5-9.5.

[0042] In step (1), the mass ratio of the silane coupling agent-modified silica to the total amount of the phenol and the ethylenediamine may be 0.05-0.2:100, preferably 0.08-0.15:100.

[0043] In step (1), the mass ratio of the dispersion stabilizer to the total amount of the phenol and the ethylenediamine may be 0.05-0.15:100, preferably 0.08-0.12:100.

[0044] In step (1), the first temperature may be 140-160° C., preferably 145-155° C. The first reaction time may be 2-3 hours, preferably 2.2-2.8 hours. The second temperature may be 90-110° C., preferably 95-105° C. The second reaction time may be 6-8 hours, preferably 6.5-7.5 hours.

[0045] In the method of the present invention, the particle size of the silicon dioxide modified by the silane coupling agent can be 1-200 nm, preferably 5-100 nm, more preferably 8-50 nm. The silane coupling agent used to modify the silicon dioxide can be purchased from Huihuang Tengfei Nanomaterial Co., Ltd., with the brand name KH560.

[0046] In the method of the present invention, the dispersion stabilizer can be at least one of a silicate, polyethylene glycol and a zwitterionic surfactant. In a more preferred embodiment, the dispersion stabilizer is a silicate. Further preferably, the dispersion stabilizer is sodium silicate. In a specific embodiment, the sodium silicate is used in the form of an aqueous solution, and the concentration of the aqueous solution of the sodium silicate can be 15-30% by weight.

[0047] In step (2), the conditions of the third reaction may include: temperature of 60-80°C, time of 1-2 hours. In a preferred case, the conditions of the third reaction include: temperature of 65-75°C, time of 1.2-1.8 hours.

[0048] In step (3), the conditions of the fourth reaction may include: temperature of 75-95°C, time of 1-2 hours. In a preferred case, the conditions of the fourth reaction include: temperature of 80-90°C, time of 1.2-1.8 hours.

[0049] In the method of the present invention, the concentrations of the first formaldehyde solution and the second formaldehyde solution may each be 35-40% by weight, preferably 36-39% by weight.

[0050] In the method of the present invention, the total amount of the first formaldehyde solution and the second formaldehyde solution is 100 weight %, the amount of the first formaldehyde solution can be 70-80 weight %, and the amount of the second formaldehyde solution can be 20-30 weight %. In a preferred case, the amount of the first formaldehyde solution is 72-76 weight %, and the amount of the second formaldehyde solution is 24-28 weight %.

[0051] In steps (1), (2) and (3), the molar ratio of the phenol to the formaldehyde in the first formaldehyde solution and the second formaldehyde solution may be 1:2.5-3, preferably 1:2.6-2.9.

[0052] In step (4), the molar ratio of the acrylamide, the 2-vinylpyridine and the 2-acrylamido-2-methylpropanesulfonic acid may be 1:1.5-2:1.5-2, preferably 1:1.6-1.9:1.6-1.9.

[0053] In step (4), the polymerization reaction conditions may include: a temperature of 40-60° C. and a time of 6-14 hours. In a preferred case, the polymerization reaction conditions include: a temperature of 45-55° C. and a time of 8-12 hours. The polymerization reaction process may be implemented in various conventional reaction devices.

[0054] In step (5), the mass ratio of the functional polymer, the nano-silicon-loaded phenolic resin cross-linking agent and water can be (0.2-0.6):(0.6-1.2):100, preferably (0.3-0.5):(0.9-1.1):100.

[0055] The specific operation process of step (5) may include: adding the functional polymer and water into a reaction device, stirring and mixing them evenly, the stirring rate is 400-1000r / min, and the time is 0.5-5h; then adding the nano-silicon-loaded phenolic resin cross-linking agent, stirring and mixing them evenly until they are fully dissolved and swollen, the stirring rate is 500-800r / min, and the time is 1-3h, and then aging them at 90-130°C to form a gel.

[0056] In step (5), the aging gelling conditions may include: a temperature of 90-130° C. and a time of 8-24 hours. In a preferred case, the aging gelling conditions include: a temperature of 95-125° C. and a time of 8-24 hours. The aging gelling process may be implemented in various conventional ovens.

[0057] In the method of the present invention, the weight average molecular weight of the functional polymer may be 8 million to 12 million, preferably 9 million to 11 million. In the present invention, the weight average molecular weight of the polymer is detected by gel chromatography.

[0058] In the method of the present invention, the water may be simulated formation water and / or reservoir formation water. The mineralization of the water may be 5×10 4 mg / L to 20×10 4 mg / L, preferably 8×10 4 mg / L to 15×10 4 mg / L.

[0059] The present invention also provides nano-silicon-loaded phenolic resin reinforced gel prepared by the above method. The nano-silicon-loaded phenolic resin reinforced gel has the characteristics of high gel strength and high temperature stability under high temperature and high salt conditions, indirectly reduces the use of phenolic formaldehyde, greatly reduces the cost, can effectively improve the heterogeneity of high temperature and high salt oil reservoirs, and improves the crude oil recovery rate.

[0060] The present invention also provides the application of the nano-silicon loaded phenolic resin reinforced gel prepared by the above method in the process of recovering crude oil. In the actual application process, the permeability of the cracks blocked by the nano-silicon loaded phenolic resin reinforced gel is only 75mD, and the blocking rate is as high as 99.8%.

[0061] The nano-silicon loaded phenolic resin reinforced gel and its preparation method and application are further described below by examples. The examples are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.

[0062] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0063] Example 1

[0064] (1) Phenol and ethylenediamine are added to a reaction device at a molar ratio of 1:0.07, sodium hydroxide solution is continuously added dropwise, and the pH value of the mixed solution is tested using a pH meter and adjusted to 9, and silicon dioxide modified by a silane coupling agent (particle size is 15 nm, the grade of the silane coupling agent used for modification is KH560, the same below) and an aqueous solution of sodium silicate with a mass concentration of 20% by weight are added to react at 150° C. for 2.5 hours, and then the reaction temperature is reduced to 100° C. and reacted for 7 hours, wherein the mass ratio of the silicon dioxide modified by the silane coupling agent to the total amount of the phenol and the ethylenediamine is 0.1:100, and the mass ratio of the sodium silicate to the total amount of the phenol and the ethylenediamine is 0.1:100, to obtain a reaction solution I.

[0065] (2) Adding a formaldehyde solution having a mass concentration of 37 wt % to the reaction solution I obtained in step (1) and reacting the mixture at 70° C. for 1.5 h to obtain a reaction solution II.

[0066] (3) adding a formaldehyde solution with a mass concentration of 37 wt % to the reaction solution II obtained in step (2) and reacting at 85° C. for 1.5 h. Based on the total amount of the formaldehyde solution added in step (2) and the formaldehyde solution added in step (3), the formaldehyde solution added in step (2) is 75 wt %, the formaldehyde solution added in step (3) is 25 wt %, and the molar ratio of the phenol used in step (1) to the formaldehyde in the formaldehyde solution added in step (2) and the formaldehyde in the formaldehyde solution added in step (3) is 1:2.8, thereby obtaining a nano-silicon-loaded phenolic resin crosslinking agent. Figure 1 The infrared spectrum of the nano-silicon-loaded phenolic resin cross-linking agent is shown.

[0067] (4) Adding acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid into a reaction device at a molar ratio of 1:1.7:1.7, and reacting at 50° C. for 10 hours to obtain a functional polymer. The weight average molecular weight of the functional polymer is measured by gel chromatography and is 10 million.

[0068] (5) The functional polymer and simulated formation water obtained in step (4) are added to a reaction device and mixed evenly at a stirring rate of 500 r / min for 2 h. After stirring until fully dissolved and swollen, the nano-silicon-loaded phenolic resin cross-linking agent obtained in step (3) is added to the reaction device and mixed evenly at a stirring rate of 500 r / min for 0.5 h. The mass ratio of the functional polymer, the nano-silicon-loaded phenolic resin cross-linking agent and the simulated formation water is 0.3:0.7:100. The mixture is then placed in an oven at 100° C. for aging to obtain the nano-silicon-loaded phenolic resin reinforced gel A1 prepared by the method of the present invention. Figure 2 The pressure curve of the plugging performance test of nano-silicon loaded phenolic resin reinforced gel A1 is shown. Figure 4 This is a photo of nano-silicon loaded phenolic resin reinforced gel A1.

[0069] Example 2

[0070] (1) Phenol and ethylenediamine are added to a reaction device at a molar ratio of 1:0.1, sodium hydroxide solution is continuously added dropwise, and the pH value of the mixed solution is tested using a pH meter and adjusted to 8.5, and silica modified by a silane coupling agent and an aqueous solution of sodium silicate with a mass concentration of 15 wt % are added to react at 145° C. for 2.8 h, and then the reaction temperature is reduced to 95° C. and reacted for 7.5 h, wherein the mass ratio of the silica modified by the silane coupling agent to the total amount of the phenol and the ethylenediamine is 0.08:100, and the mass ratio of the sodium silicate to the total amount of the phenol and the ethylenediamine is 0.12:100, to obtain a reaction solution I.

[0071] (2) Adding a formaldehyde solution having a mass concentration of 37 wt % to the reaction solution I obtained in step (1) and reacting the mixture at 65° C. for 1.8 h to obtain a reaction solution II.

[0072] (3) adding a formaldehyde solution with a mass concentration of 37 wt % to the reaction solution II obtained in step (2) and reacting at 80° C. for 1.8 h. Based on the total amount of the formaldehyde solution added in step (2) and the formaldehyde solution added in step (3), the formaldehyde solution added in step (2) is 76 wt %, the formaldehyde solution added in step (3) is 24 wt %, and the molar ratio of the phenol used in step (1) to the formaldehyde in the formaldehyde solution added in step (2) and the formaldehyde in the formaldehyde solution added in step (3) is 1:2.6, thereby obtaining a nano-silicon-loaded phenolic resin crosslinking agent.

[0073] (4) acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid were added into a reaction device at a molar ratio of 1:1.6:1.6, and the mixture was reacted at 55° C. for 8 h to obtain a functional polymer. The weight average molecular weight of the functional polymer was measured by gel chromatography and was 9 million.

[0074] (5) The functional polymer and simulated formation water obtained in step (4) are added to a reaction device and mixed evenly at a stirring rate of 500 r / min for 2 h. After stirring until fully dissolved and swollen, the nano-silicon-loaded phenolic resin cross-linking agent obtained in step (3) is added to the reaction device and mixed evenly at a stirring rate of 500 r / min for 0.5 h. The mass ratio of the functional polymer, the nano-silicon-loaded phenolic resin cross-linking agent and the simulated formation water is 0.5:0.9:100. The mixture is then placed in an oven at 90° C. for aging to obtain the nano-silicon-loaded phenolic resin reinforced gel A2 prepared by the method of the present invention.

[0075] Example 3

[0076] (1) Phenol and ethylenediamine are added to a reaction device at a molar ratio of 1:0.08, sodium hydroxide solution is continuously added dropwise, and the pH value of the mixed solution is tested using a pH meter and adjusted to 9.5, silicon dioxide modified by a silane coupling agent and an aqueous solution of sodium silicate with a mass concentration of 30 wt % are added to react at 155° C. for 2.2 h, and then the reaction temperature is lowered to 105° C. and reacted for 6.5 h, wherein the mass ratio of the silicon dioxide modified by the silane coupling agent to the total amount of the phenol and the ethylenediamine is 0.15:100, and the mass ratio of the sodium silicate to the total amount of the phenol and the ethylenediamine is 0.08:100, to obtain a reaction solution I.

[0077] (2) Adding a formaldehyde solution having a mass concentration of 37 wt % to the reaction solution I obtained in step (1) and reacting the mixture at 75° C. for 1.2 h to obtain a reaction solution II.

[0078] (3) adding a formaldehyde solution with a mass concentration of 37 wt % to the reaction solution II obtained in step (2) and reacting at 90° C. for 1.2 h. Based on the total amount of the formaldehyde solution added in step (2) and the formaldehyde solution added in step (3), the formaldehyde solution added in step (2) is 72 wt %, the formaldehyde solution added in step (3) is 28 wt %, and the molar ratio of the phenol used in step (1) to the formaldehyde in the formaldehyde solution added in step (2) and the formaldehyde in the formaldehyde solution added in step (3) is 1:2.9, thereby obtaining a nano-silicon-loaded phenolic resin crosslinking agent.

[0079] (4) Adding acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid into a reaction device at a molar ratio of 1:1.9:1.9, and reacting at 45° C. for 12 hours to obtain a functional polymer. The weight average molecular weight of the functional polymer is measured by gel chromatography and is 11 million.

[0080] (5) adding the functional polymer and simulated formation water obtained in step (4) into a reaction device and mixing them evenly, stirring at a rate of 500 r / min for 2 h, stirring until fully dissolved and swollen, then adding the nano-silicon-loaded phenolic resin cross-linking agent obtained in step (3) into the reaction device and mixing them evenly, stirring at a rate of 500 r / min for 0.5 h, wherein the mass ratio of the functional polymer, the nano-silicon-loaded phenolic resin cross-linking agent and the simulated formation water is 0.4:1.1:100, and then placing in an oven at 125° C. for aging to obtain the nano-silicon-loaded phenolic resin reinforced gel A3 prepared by the method of the present invention.

[0081] Example 4

[0082] Nano-silicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (1), the mass ratio of the silane coupling agent-modified silica to the total amount of the phenol and the ethylenediamine was 0.06:100, thereby obtaining nano-silicon-loaded phenolic resin reinforced gel A4 prepared by the method of the present invention.

[0083] Example 5

[0084] Nano-silicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (3), the molar ratio of phenol used in step (1) to the formaldehyde solution added in step (2) and the formaldehyde in the formaldehyde solution added in step (3) was 1:2.5, thereby obtaining nano-silicon-loaded phenolic resin reinforced gel A5 prepared by the method of the present invention.

[0085] Example 6

[0086] Nano-silicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (4), the molar ratio of acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid was adjusted to 1:1.5:1.5, thereby obtaining nano-silicon-loaded phenolic resin reinforced gel A6 prepared by the method of the present invention.

[0087] Comparative Example 1

[0088] Nano-silicon-loaded phenolic resin reinforced jelly was prepared according to the method of Example 1, except that in step (1), no sodium silicate was added, to obtain nano-silicon-loaded phenolic resin reinforced jelly D1.

[0089] Comparative Example 2

[0090] Nano-silicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (1), the molar ratio of phenol to ethylenediamine was adjusted to 1:0.06, thereby obtaining nano-silicon-loaded phenolic resin reinforced gel D2.

[0091] Comparative Example 3

[0092] Nano-silicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (1), the pH value of the mixed solution of phenol and ethylenediamine was adjusted to 7.0, thereby obtaining nano-silicon-loaded phenolic resin reinforced gel D3.

[0093] Comparative Example 4

[0094] Nano-silicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (4), the molar ratio of acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid was adjusted to 1:1.4:1.4 to obtain nano-silicon-loaded phenolic resin reinforced gel D4.

[0095] Comparative Example 5

[0096] Nanosilicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (5), the mass ratio of the functional polymer, the nanosilicon-loaded phenolic resin crosslinker and the simulated formation water was adjusted to 0.1:0.5:100 to obtain nanosilicon-loaded phenolic resin reinforced gel D5.

[0097] Comparative Example 6

[0098] Nano-silicon-loaded phenolic resin reinforced gel was prepared according to the method of Example 1, except that in step (1), a silane coupling agent-modified silica and an aqueous solution of sodium silicate were added and reacted at 180°C for 2.5 hours, and then the reaction temperature was reduced to 90°C and reacted for 7 hours to obtain nano-silicon-loaded phenolic resin reinforced gel D6.

[0099] Test Case

[0100] The various properties of the nano-silicon-loaded phenolic resin reinforced gel prepared in the above examples and comparative examples were tested according to the following methods.

[0101] (1) High temperature and high salt gelation effect test: The GSC strength code method was used to observe the flow state of the sample at 120°C for 12h, 1d, 2d, 3d, 10d, 30d, 60d and 90d. The sample with high deformation and non-flowing gel indicates that the strength reaches F level, the sample with moderate deformation and non-flowing gel indicates that the strength reaches G level, and the sample with slight deformation and non-flowing gel indicates that the strength reaches H level. The dehydration rate of the sample is the ratio of the difference between the weight of the gelling liquid before gelation and the weight of the gel after gelation to the weight of the gelling liquid before gelation.

[0102] (2) Plugging performance test: Fractures were created by splitting the real core of a tight oil reservoir. The fracture width was 1 mm, the core length was 10 cm, the diameter was 2.5 cm, and the core matrix permeability was 0.01 mD. Simulated formation water drive was used to establish a water drive dominant seepage channel. The core drive device was used to test the samples injected into the core fractures and aged into gel. Figure 3The core displacement device diagram for the plugging performance test in the present invention is shown. The core displacement device includes a plunger pump, a high-temperature and high-pressure intermediate container, a core clamp, a high-temperature and high-pressure oven, a back pressure valve, and a hand pump. The specific operation steps are as follows: (1) Dry the core sample at 65°C for 24 hours, and use the method of vacuuming and pressurizing saturated crude oil to establish the initial oil saturation; (2) Carry out a water drive test, and the core is displaced with simulated formation water. During the test, the injection pressure was recorded, the confining pressure was 2MPa, the back pressure was 5MPa, the temperature was 120℃, and the injection rate was 0.5mL / min. The displacement solution was replaced when the injection pressure was stable at each stage; (3) Injection of plugging agent, replace the high-temperature and high-pressure intermediate container with enhanced gel, inject 0.5 fracture volume of gelling liquid, and track the confining pressure of 2MPa, back pressure of 5MPa, temperature of 120℃, injection rate of 0.5mL / min, and age in a high-temperature and high-pressure oven until complete gelation; (4) Secondary water flooding test, using simulated formation water for displacement. During the test, the injection pressure was recorded, the confining pressure was 2MPa, back pressure was 5MPa, temperature of 120℃, and injection rate of 0.5mL / min.

[0103] The gel strength test results of the high temperature and high salt gel effect test of the nano-silicon loaded phenolic resin reinforced gel of Examples 1-6 and Comparative Examples 1-6 are shown in Table 1 below.

[0104] Table 1

[0105]

[0106] The dehydration rate test results of the high temperature and high salt gelling effect test of the nano-silicon loaded phenolic resin reinforced gel of Examples 1-6 and Comparative Examples 1-6 are shown in Table 2 below.

[0107]

[0108] The test results of the plugging performance test of the nano-silicon loaded phenolic resin reinforced gel of Examples 1-6 and Comparative Examples 1-6 are shown in Table 3 below.

[0109] Table 3

[0110]

[0111]

[0112] It can be seen from the results in Table 1, Table 2 and Table 3 that the nano-silicon-loaded phenolic resin reinforced gel prepared according to the method described in the present invention has significantly higher gel strength and high temperature stability.

[0113] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing nano-silicon-loaded phenolic resin reinforced jelly, characterized in that: The method comprises the following steps: (1) mixing phenol and ethylenediamine at a molar ratio of 1:0.07-0.1, adjusting the pH value to 8-10, and then subjecting the obtained mixture to a first reaction with silica modified by a silane coupling agent and a dispersion stabilizer at a first temperature, and then cooling to a second temperature for a second reaction to obtain a reaction solution I; (2) subjecting the reaction solution I to a third reaction with the first formaldehyde solution to obtain a reaction solution II; (3) performing a fourth reaction on the reaction solution II and the second formaldehyde solution to obtain a nano-silicon-loaded phenolic resin cross-linking agent; (4) polymerizing acrylamide, 2-vinylpyridine and 2-acrylamido-2-methylpropanesulfonic acid at a molar ratio of 1:1.5-2:1.5-2 to obtain a functional polymer; (5) mixing the functional polymer and water, and then mixing the obtained mixture with the nano-silicon-loaded phenolic resin cross-linking agent, and then aging at 90-130° C. to form a gel; Wherein, the first temperature is 30-80°C higher than the second temperature; The concentrations of the first formaldehyde solution and the second formaldehyde solution are the same, and are both 35-40% by weight. Taking the total amount of the first formaldehyde solution and the second formaldehyde solution as 100% by weight, the amount of the first formaldehyde solution is 70-80% by weight, and the amount of the second formaldehyde solution is 20-30% by weight.

2. The method according to claim 1, characterized in that In step (1), the mass ratio of the silane coupling agent-modified silica to the total amount of the phenol and the ethylenediamine is 0.05-0.2:100; and / or The mass ratio of the dispersion stabilizer to the total amount of the phenol and the ethylenediamine is 0.05-0.15:

100.

3. The method according to claim 1 or 2, characterized in that: In step (1), the first temperature is 140-160° C., the first reaction time is 2-3 h, the second temperature is 90-110° C., and the second reaction time is 6-8 h.

4. The method according to any one of claims 1 to 3, characterized in that: The particle size of the silicon dioxide modified by the silane coupling agent is 1-200 nm.

5. The method according to any one of claims 1 to 4, characterized in that: The dispersion stabilizer is at least one of silicate, polyethylene glycol and zwitterionic surfactant.

6. The method according to claim 1, characterized in that In step (2), the conditions of the third reaction include: temperature of 60-80° C. and time of 1-2 h.

7. The method according to claim 1, characterized in that In step (3), the conditions of the fourth reaction include: temperature of 75-95° C. and time of 1-2 h.

8. The method according to claim 1, characterized in that: In steps (1), (2) and (3), the molar ratio of the phenol to the formaldehyde in the first formaldehyde solution and the second formaldehyde solution is 1:2.5-3.

9. The method according to claim 1, characterized in that: The weight average molecular weight of the functional polymer is 8 million to 12 million.

10. The method according to claim 1, characterized in that In step (5), the mass ratio of the functional polymer, the nano-silicon-loaded phenolic resin cross-linking agent and water is (0.2-0.6): (0.6-1.2):

100.

11. Nano-silicon-loaded phenolic resin reinforced jelly prepared by the method according to any one of claims 1 to 10.

12. Use of the nano-silicon-loaded phenolic resin reinforced gel according to claim 11 in the process of recovering crude oil.

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