Sulfonic acid regulated silicon-based nano oil displacement agent as well as preparation method and application thereof

Abstract

The invention provides a sulfonic acid regulated silicon-based nano oil displacement agent as well as a preparation method and application thereof. The preparation raw materials of the silicon-based nano oil displacement agent comprise the following components in parts by weight: 2-10 parts of a silane coupling agent, 0.05-5 parts of sulfonate and 2-20 parts of a strong alkali compound. The preparation method comprises the following steps: dissolving a strong alkali compound in a part of a solvent A to obtain a strong alkaline solution; dissolving sulfonate in the residual solvent A, dropwise adding a silane coupling agent into the residual solvent A, and uniformly mixing to obtain a mixed solution; after the mixed solution reacts, adding a strong alkaline solution into the mixed solution, and stopping the reaction to obtain the silicon-based nano oil displacement agent regulated and controlled by the sulfonic acid. The size of the silicon-based nano oil-displacing agent regulated and controlled by sulfonic acid can be precisely regulated and controlled, and the silicon-based nano oil-displacing agent is resistant to temperature and salt, can adapt to a harsh stratum environment, and is simple in synthesis step, easy in experimental condition regulation and control, mild in reaction process, low in cost and high in synthesis repeatability.

Description

Technical Field

[0001] The present invention belongs to the technical field of oilfield chemistry, and specifically relates to a sulfonic acid-regulated silicon-based nano oil-displacing agent, a preparation method and application thereof, and more specifically relates to a sulfonic acid-regulated silicon-based nano oil-displacing agent under a microchemical environment. Background Art

[0002] With the development of oil and gas reservoirs, most oil fields are currently in the middle and late stages of development. There are generally problems such as high temperature and high mineralization, poor formation environment, small matrix pore throats (between 50-800nm ​​at the micro-nano level), large fluid flow resistance, and difficulty in replenishing formation energy, making exploitation difficult. The recoverable oil resources in low-permeability and ultra-low-permeability oil and gas reservoirs in unconventional oil reservoirs account for 4 / 5 of the proven reserves, and the development prospects are considerable. Therefore, improving the recovery rate of low-permeability oil and gas reservoirs is a key measure to ensure national energy security under the background of "increasing reserves and production".

[0003] In the existing technology, low permeability reservoirs are developed by nanofluid flooding. Nano oil-displacing agents can significantly reduce water injection resistance and improve recovery. However, the existing nano oil-displacing technology mainly involves compounding nano materials with surfactants or performing surface modification. It still works in the original water flooding channel without expanding the impact. In addition, nano oil-displacing agents have been less studied under high temperature and high salt conditions, making it difficult to meet the actual requirements of significantly improving recovery.

[0004] Silicon dots are spherical silicon-based nanomaterials with a size of less than 10 nm. They have the advantages of high abundance, high temperature resistance, high toughness, non-toxicity, environmental friendliness, physiological inertness, diverse modification methods, good stability, abundant reserves and easy mass production, and are expected to replace traditional nano oil-displacing agents. These advantages have made silicon dots a hot topic, especially in the field of chemical enhanced oil recovery, where they have great potential application value. However, the existing methods for preparing silicon dots are numerous and complex, and it is difficult to accurately control their surface functional groups. In addition, the oil-displacing agent systems prepared from silicon dots are mostly used for oil-displacing experiments under indoor normal temperature and salt-free conditions, and have poor reservoir adaptability.

[0005] Therefore, how to provide a silicon dot oil displacement agent with simple synthesis steps, easy-to-control experimental conditions, mild reaction process, low cost and high synthetic repeatability, precise size controllable under microchemical environment, temperature and salt resistance, and adaptability to harsh formation environment has become a technical problem that needs to be solved urgently. Summary of the invention

[0006] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a sulfonic acid-regulated silicon-based nano oil-displacing agent and a preparation method and application thereof. In the present invention, silicon dots are obtained by reacting a silane coupling agent, and the silicon dots are modified with a sulfonate as a modifier to obtain a sulfonic acid-regulated silicon-based nano oil-displacing agent; the sulfonic acid-regulated silicon-based nano oil-displacing agent provided by the present invention has a size that can be precisely regulated, is temperature-resistant and salt-resistant, has good stability, can adapt to harsh formation environments, and has simple synthesis steps, easy-to-regulate experimental conditions, a mild reaction process, low cost, and high synthetic repeatability.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, wherein the raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight:

[0009] 2 to 10 parts of silane coupling agent, 0.05 to 5 parts of sulfonate, and 2 to 20 parts of strong base compound.

[0010] In the present invention, silicon dots are obtained by reacting a silane coupling agent, and sulfonate is used as a modifier to modify the silicon dots, thereby obtaining a sulfonic acid-regulated silicon-based nano oil-displacing agent that can be precisely regulated in size, is resistant to temperature and salt, has good stability, and can adapt to harsh formation environments.

[0011] In the present invention, by controlling the amount of sulfonate within a specific range, a silicon-based nano oil-displacing agent with good performance can be prepared. If the amount of sulfonate is small, its modification effect on silicon dots is poor, and the performance of the silicon-based nano oil-displacing agent prepared thereby is also poor; if the amount of sulfonate is too much, it will cause a waste of raw materials.

[0012] In the present invention, in the raw materials for preparing the sulfonic acid-regulated silicon-based nano-oil-displacing agent, the weight proportion of the silane coupling agent can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts.

[0013] In the raw materials for preparing the sulfonic acid-regulated silicon-based nano oil-displacing agent, the weight proportion of sulfonate can be 0.05 parts, 0.1 parts, 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts, etc.

[0014] In the raw materials for preparing the sulfonic acid-regulated silicon-based nano-oil-displacing agent, the weight proportion of the strong base compound can be 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts or 20 parts.

[0015] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved and realized.

[0016] As a preferred technical solution of the present invention, the silane coupling agent is selected from any one of ethyldimethylsilane (EDS), tris(trimethylsiloxy)silane (TTLS) or vinyltris(2-methoxyethoxy)silane (VMTS) or a combination of at least two thereof.

[0017] Preferably, the sulfonic acid salt is selected from any one of sodium dodecylbenzenesulfonate (SDBS), p-aminobenzenesulfonic acid (ABS) or sodium p-aminobenzenesulfonate (SASS), or a combination of at least two thereof.

[0018] As a preferred technical solution of the present invention, the strong base compound is selected from sodium hydroxide and / or potassium hydroxide.

[0019] Preferably, the raw materials for preparing the sulfonic acid-regulated silicon-based nano oil-displacing agent also include 100 to 300 parts by weight of solvent A, for example, 100 parts by weight, 120 parts by weight, 140 parts by weight, 160 parts by weight, 180 parts by weight, 200 parts by weight, 220 parts by weight, 240 parts by weight, 260 parts by weight, 280 parts by weight or 300 parts by weight, etc.

[0020] Preferably, the solvent comprises water.

[0021] As a preferred technical solution of the present invention, the average particle size of the silicon-based nano oil-displacing agent is ≤10 nm, for example, it can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm.

[0022] In a second aspect, the present invention provides a method for preparing the sulfonic acid-regulated silicon-based nano oil-displacing agent as described in the first aspect, the preparation method comprising the following steps:

[0023] (1) dissolving a strong base compound in part of solvent A to obtain a strong base solution;

[0024] Dissolving the sulfonate in the remaining solvent A, adding a silane coupling agent dropwise thereto, and mixing evenly to obtain a mixed solution;

[0025] (2) After the mixed solution obtained in step (1) is reacted, a strong alkaline solution is added thereto to stop the reaction, thereby obtaining the sulfonic acid-regulated silicon-based nano oil-displacing agent.

[0026] In the present invention, sulfonate and silane coupling agent are mixed together, and in the reaction process, after the silane coupling agent reacts to obtain silicon dots, the sulfonate modifies the silicon dots, and then the pH of the reaction system is adjusted by adding a strong alkaline solution to quickly stop the reaction, thereby obtaining a silicon-based nano oil-displacing agent based on sulfonic acid regulation in a microchemical environment, which can be precisely regulated in size, is heat-resistant and salt-resistant, has good stability, and can adapt to harsh formation environments. The silicon-based nano oil-displacing agent provided by the present invention has simple synthesis steps, easy-to-regulate experimental conditions, mild reaction process, low cost, and high synthetic repeatability.

[0027] As a preferred technical solution of the present invention, the mass concentration of the strong alkaline solution is 2-20%, for example, it can be 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18% or 20%.

[0028] Preferably, the method of dissolving the sulfonate salt in the solvent comprises stirring.

[0029] Preferably, the stirring time is 5 to 30 min (for example, it may be 5 min, 7 min, 10 min, 12 min, 15 min, 18 min, 20 min, 23 min, 25 min, 27 min or 30 min, etc.), and the stirring speed is 150 to 300 rpm (for example, it may be 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm, 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm or 300 rpm, etc.).

[0030] Preferably, the silane coupling agent is added dropwise.

[0031] Preferably, the method of adding the silane coupling agent and mixing uniformly includes stirring.

[0032] Preferably, the stirring time is 5 to 10 min (for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc.), and the stirring speed is 150 to 300 rpm (for example, it can be 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm, 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm or 300 rpm, etc.).

[0033] As a preferred technical solution of the present invention, the reaction temperature is 120-180°C (for example, it can be 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C or 180°C, etc.), and the reaction time is 4-20h (for example, it can be 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h or 20h, etc.).

[0034] Preferably, the reaction is carried out under stirring conditions, and the stirring speed is 150-300 rpm (for example, it can be 150 rpm, 160 rpm, 170 rpm, 180 rpm, 190 rpm, 200 rpm, 220 rpm, 240 rpm, 260 rpm, 280 rpm or 300 rpm, etc.).

[0035] Preferably, after adding the strong alkaline solution, the pH of the reaction system is 6 to 8, for example, 6, 6.5, 7, 7.5 or 8.

[0036] Preferably, the step of post-treatment is further included after stopping the reaction.

[0037] Preferably, the post-treatment method comprises: placing the reaction solution in a dialysis bag for dialysis and freeze-drying.

[0038] Preferably, the dialysate used in the dialysis is deionized water.

[0039] Preferably, the dialysis time is 48 to 72 hours.

[0040] It should be noted that, during dialysis in the present invention, the dialysate is replaced every 6 hours.

[0041] As a preferred technical solution of the present invention, the preparation method specifically comprises the following steps:

[0042] (1) dissolving a strong alkaline compound in a portion of solvent A to obtain a strong alkaline solution having a mass concentration of 2 to 20%;

[0043] Under the condition of a rotation speed of 200 rpm, the sulfonate is placed in the remaining solvent A, and stirred for 5 to 30 minutes to dissolve the sulfonate, and then a silane coupling agent is added dropwise thereto, and stirring is continued for 5 to 10 minutes to obtain a mixed solution;

[0044] (2) reacting the mixed solution obtained in step (1) at 120 to 180° C. for 4 to 20 hours, adding a strong alkaline solution until the pH of the reaction system is 6 to 8, and stopping the reaction;

[0045] The obtained reaction solution is placed in a dialysis bag, immersed in deionized water, dialyzed for 48 to 72 hours (the deionized water is replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0046] In a third aspect, the present invention provides a silicon-based nano oil-displacing agent system, wherein the silicon-based nano oil-displacing agent system comprises the sulfonic acid-regulated silicon-based nano oil-displacing agent as described in the first aspect and solvent B.

[0047] Preferably, the solvent B comprises water.

[0048] Preferably, the mass concentration of the silicon-based nano oil-displacing agent in the silicon-based nano oil-displacing agent system is 0.01-0.5%, for example, it can be 0.01%, 0.02%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5%, etc.

[0049] It should be noted that, in the present invention, the preparation method of the silicon-based nano oil-displacing agent system illustratively includes but is not limited to: dispersing the silicon-based nano oil-displacing agent in deionized water to obtain the silicon-based nano oil-displacing agent system.

[0050] In a fourth aspect, the present invention provides a use of the silicon-based nano oil-displacing agent system as described in the third aspect, wherein the silicon-based nano oil-displacing agent system is used for recovering low-permeability oil reservoirs.

[0051] Preferably, the permeability of the low permeability oil reservoir is 10-500 mD, for example, it may be 10 mD, 50 mD, 100 mD, 150 mD, 200 mD, 250 mD, 300 mD, 350 mD, 400 mD, 450 mD or 500 mD.

[0052] Preferably, the silicon-based nano oil-displacing agent system is used for recovery at a temperature lower than 100°C (e.g., 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 99°C, etc.), and a mineralization of ≤8×10 4 mg / L (for example, 1×10 4 mg / L, 2×10 4 mg / L、3×10 4 mg / L, 4×10 4 mg / L, 5×10 4 mg / L, 6×10 4 mg / L、7×10 4 mg / L or 8×10 4 mg / L, etc.) of oil reservoirs.

[0053] Preferably, the silicon-based nano oil-displacing agent system is used to recover oil reservoirs with a crude oil viscosity of ≤6000mPa·s (for example, it may be 1000mPa·s, 1500mPa·s, 2000mPa·s, 2500mPa·s, 3000mPa·s, 3500mPa·s, 4000mPa·s, 4500mPa·s, 5000mPa·s, 5500mPa·s or 6000mPa·s, etc.).

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) In the present invention, the raw materials and preparation method of the sulfonic acid-regulated silicon-based nano-oil-displacing agent are designed to prepare a silicon-based nano-oil-displacing agent with precisely regulated size, temperature resistance and salt resistance, good stability, and adaptability to harsh formation environments. The average particle size is ≤10nm, the Zeta potential is 35.12-40.53mV, and the temperature resistance and salt resistance at 80°C are ≥12×10 4 mg / L, the heat and salt resistance at 90℃ is ≥8×10 4 mg / L, heat and salt resistance at 100℃≥4×10 4 mg / L, heat and salt resistance at 110℃≥1×10 4 mg / L.

[0056] (2) The present invention provides a sulfonic acid-regulated silicon-based nano-oil-displacing agent with simple synthesis steps, easy-to-control experimental conditions, mild reaction process, low cost and high synthesis repeatability.

[0057] (3) The present invention designs the content of the silicon-based nano-oil-displacing agent regulated by sulfonic acid in the silicon-based nano-oil-displacing agent system to obtain a silicon-based nano-oil-displacing agent system with a higher recovery rate, wherein the recovery rate is ≥53.77%, specifically 53.77-63.38%. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a graph showing the particle size characterization results of the oil displacing agent in the oil displacing agent system provided in Application Example 1-1;

[0059] Figure 2 This is a graph showing the particle size characterization results of the oil-displacing agent in the oil-displacing agent system provided in Comparative Example 2-1;

[0060] Figure 3 It is a comparison diagram of the Zeta potential of the oil displacement agent system provided by Application Example 1-1 and Comparative Application Example 1-2;

[0061] Figure 4 It is a graph showing the temperature and salt resistance performance of the oil displacement agent provided in Example 1 and Comparative Example 1 at different temperatures. DETAILED DESCRIPTION

[0062] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0063] The sources of some components in the following embodiments, comparative examples, application examples and comparative application examples are as follows:

[0064] The sandstone outcrop cores were purchased from Haian Petroleum Research Instrument Co., Ltd. The cores were about 10 cm in length, 2.5 cm in diameter, and had a permeability of 1-50 mD;

[0065] Simulated oil: crude oil produced by Ta-Yilian Oilfield and kerosene purchased from Sinopec Qingdao Refining and Chemical Co., Ltd. were mixed in a mass ratio of 1:4;

[0066] The silicon sources used were ethyldimethylsilane (EDS), tris(trimethylsiloxy)silane (TTLS), vinyltri(2-methoxyethoxy)silane (VMTS), sulfonates sodium dodecylbenzenesulfonate (SDBS), p-aminobenzenesulfonic acid (ABS), sodium p-aminobenzenesulfonate (SASS), all from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0067] Sodium hydroxide, sodium chloride, calcium chloride, and magnesium chloride were purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0068] Dialysis bags (MD44, 1000 molecular weight) were from Beijing Yikang Science and Trade Biological Reagent Consumables Laboratory;

[0069] Unless otherwise specified in the following embodiments, comparative examples, application examples and application comparative examples, the water used is deionized water.

[0070] Example 1

[0071] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, wherein the raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight:

[0072] 2 parts of ethyldimethylsilane, 2 parts of sodium dodecylbenzenesulfonate, 10 parts of sodium hydroxide and 186 parts of water.

[0073] The preparation method of the silicon-based nano oil-displacing agent is as follows:

[0074] (1) dissolving 10 parts of sodium hydroxide in 90 parts of water to obtain a sodium hydroxide solution with a mass concentration of 10%;

[0075] Under the condition of a rotation speed of 200 rpm, 2 parts of sodium dodecylbenzene sulfonate were placed in 96 parts of 1% ethanol and stirred for 20 minutes to dissolve the sodium dodecylbenzene sulfonate. Then 2 parts of ethyldimethylsilane were added dropwise thereto and stirred for 10 minutes to obtain a mixed solution.

[0076] (2) reacting the mixed solution obtained in step (1) at 140° C. for 14 h, adding sodium hydroxide solution until the pH of the reaction system is 7, and stopping the reaction;

[0077] The obtained reaction solution was placed in a dialysis bag, immersed in deionized water, dialyzed for 60 hours (the deionized water was replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0078] Example 2

[0079] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, wherein the raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight:

[0080] 10 parts of tris(trimethylsiloxy)silane, 5 parts of p-aminobenzenesulfonic acid, 20 parts of sodium hydroxide and 165 parts of water.

[0081] The preparation method of the silicon-based nano oil-displacing agent is as follows:

[0082] (1) dissolving 20 parts of sodium hydroxide in 80 parts of water to obtain a sodium hydroxide solution with a mass concentration of 20%;

[0083] At a rotation speed of 300 rpm, p-aminobenzenesulfonic acid was placed in 85 parts of water, and stirred for 20 minutes to dissolve the p-aminobenzenesulfonic acid. Then, tris(trimethylsiloxy)silane was added dropwise thereto, and stirring was continued for 10 minutes to obtain a mixed solution.

[0084] (2) After the mixed solution obtained in step (1) was reacted at 120° C. for 20 h, sodium hydroxide was added thereto until the pH of the reaction system reached 7 to stop the reaction;

[0085] The obtained reaction solution was placed in a dialysis bag, immersed in deionized water, dialyzed for 72 hours (the deionized water was replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0086] Example 3

[0087] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, wherein the raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight:

[0088] 2 parts of vinyl tris(2-methoxyethoxy)silane, 0.05 parts of sodium p-aminobenzenesulfonate, 2 parts of potassium hydroxide and 195.95 parts of water.

[0089] The preparation method of the silicon-based nano oil-displacing agent is as follows:

[0090] (1) dissolving 2 parts of potassium hydroxide in 98 parts of water to obtain a potassium hydroxide solution with a mass concentration of 2%;

[0091] At a rotation speed of 150 rpm, 0.05 parts of sodium p-aminobenzenesulfonate were placed in 97.95 parts of water, and the mixture was stirred for 10 minutes to dissolve the sodium p-aminobenzenesulfonate. Then, 2 parts of vinyl tris(2-methoxyethoxy)silane were added dropwise thereto, and the mixture was stirred for 8 minutes to obtain a mixed solution.

[0092] (2) After the mixed solution obtained in step (1) was reacted at 150° C. for 12 h, potassium hydroxide solution was added thereto until the pH of the reaction system reached 8 to stop the reaction;

[0093] The obtained reaction solution was placed in a dialysis bag, immersed in deionized water, dialyzed for 48 hours (the deionized water was replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0094] Example 4

[0095] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, wherein the raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight:

[0096] 8 parts of tris(trimethylsiloxy)silane, 4 parts of sodium dodecylbenzenesulfonate, 5 parts of sodium hydroxide and 133 parts of water.

[0097] The preparation method of the silicon-based nano oil-displacing agent is as follows:

[0098] (1) dissolving 5 parts of sodium hydroxide in 45 parts of water to obtain a sodium hydroxide solution with a mass concentration of 10%;

[0099] At a rotation speed of 250 rpm, 4 parts of sodium dodecylbenzene sulfonate were placed in 88 parts of water, and stirred for 15 minutes to dissolve the sodium dodecylbenzene sulfonate. Then, 8 parts of tris(trimethylsiloxy)silane were added dropwise thereto, and stirring was continued for 9 minutes to obtain a mixed solution.

[0100] (2) reacting the mixed solution obtained in step (1) at 180° C. for 4 h, adding sodium hydroxide solution until the pH of the reaction system is 6, and stopping the reaction;

[0101] The obtained reaction solution is placed in a dialysis bag, immersed in deionized water, dialyzed for 48 to 72 hours (the deionized water is replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0102] Example 5

[0103] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, wherein the raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight:

[0104] 5 parts of vinyltri(2-methoxyethoxy)silane, 3 parts of p-aminobenzenesulfonic acid, 10 parts of potassium hydroxide and 132 parts of water.

[0105] The preparation method of the silicon-based nano oil-displacing agent is as follows:

[0106] (1) dissolving 10 parts of potassium hydroxide in 40 parts of water to obtain a potassium hydroxide solution with a mass concentration of 20%;

[0107] At a rotation speed of 180 rpm, 3 parts of p-aminobenzenesulfonic acid were placed in 92 parts of water, and the mixture was stirred for 20 minutes to dissolve the p-aminobenzenesulfonic acid. Then, 5 parts of vinyltri(2-methoxyethoxy)silane were added dropwise thereto, and the mixture was stirred for 8 minutes to obtain a mixed solution.

[0108] (2) reacting the mixed solution obtained in step (1) at 160° C. for 15 h, adding potassium hydroxide solution until the pH of the reaction system is 7, and stopping the reaction;

[0109] The obtained reaction solution was placed in a dialysis bag, immersed in deionized water, dialyzed for 54 hours (the deionized water was replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0110] Example 6

[0111] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, which is different from Example 1 only in that, in the raw materials for preparing the silicon-based nano oil-displacing agent, the weight parts of ethyldimethylsilane are 2 parts, and the weight parts of sodium dodecylbenzene sulfonate are 5 parts, and other conditions are the same as those in Example 1.

[0112] Example 7

[0113] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, which is different from Embodiment 1 only in that, in the raw materials for preparing the silicon-based nano oil-displacing agent, the weight proportion of ethyldimethylsilane is 10 parts, the weight proportion of sodium dodecylbenzene sulfonate is 0.05 parts, and other conditions are the same as those in Embodiment 1.

[0114] Example 8

[0115] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, which is different from Example 1 only in that, in the raw materials for preparing the silicon-based nano oil-displacing agent, the weight parts of ethyldimethylsilane are 2 parts, and the weight parts of sodium dodecylbenzene sulfonate are 6 parts, and other conditions are the same as those in Example 1.

[0116] Example 9

[0117] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, which is different from Example 1 only in that, in the raw materials for preparing the silicon-based nano oil-displacing agent, the weight portion of ethyldimethylsilane is 10 parts, the weight portion of sodium dodecylbenzene sulfonate is 0.03 parts, and other conditions are the same as those in Example 1.

[0118] Example 10

[0119] This embodiment provides a sulfonic acid-regulated silicon-based nano oil-displacing agent, wherein the raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight:

[0120] 2 parts of ethyldimethylsilane, 2 parts of sodium dodecylbenzenesulfonate, 10 parts of sodium hydroxide and 186 parts of water.

[0121] The preparation method of the silicon-based nano oil-displacing agent is as follows:

[0122] (1) dissolving 10 parts of sodium hydroxide in 90 parts of water to obtain a sodium hydroxide solution with a mass concentration of 10%;

[0123] Under the condition of a rotation speed of 200 rpm, 2 parts of sodium dodecylbenzene sulfonate were placed in 48 parts of 1% ethanol and stirred for 20 minutes to dissolve the sodium dodecylbenzene sulfonate to obtain a sodium dodecylbenzene sulfonate solution;

[0124] (2) 2 parts of ethyldimethylsilane were added dropwise to 48 parts of water, stirred for 10 minutes, heated to 140° C., reacted for 10 hours, and then sodium dodecylbenzene sulfonate solution was added thereto. After the modification reaction was carried out for 10 hours, sodium hydroxide solution was added thereto until the pH of the reaction system was 7, and the reaction was stopped;

[0125] The obtained reaction solution was placed in a dialysis bag, immersed in deionized water, dialyzed for 60 hours (the deionized water was replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0126] Comparative Example 1

[0127] This comparative example provides an oil-displacing agent, which is nano-silicon dioxide powder (with an average particle size of 50 to 60 nm, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.).

[0128] Comparative Example 2

[0129] This comparative example provides an oil-displacing agent, which includes silicon dioxide powder (average particle size ≤ 10 nm, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and sodium dodecylbenzene sulfonate;

[0130] The preparation method of the oil displacing agent is as follows:

[0131] The silicon dioxide powder and sodium dodecylbenzene sulfonate are uniformly mixed in a mass ratio of 1:1 to obtain the oil displacement agent.

[0132] Comparative Example 3

[0133] This comparative example provides an oil-displacing agent, and the raw materials for preparing the oil-displacing agent include the following components in parts by weight: 2 parts of ethyldimethylsilane, 2 parts of sodium dodecylbenzenesulfonate and 186 parts of water.

[0134] The preparation method of the oil displacing agent is as follows:

[0135] (1) at a rotation speed of 200 rpm, 2 parts of sodium dodecylbenzene sulfonate were placed in 96 parts of ethanol, stirred for 20 min to dissolve the sodium dodecylbenzene sulfonate, and then 2 parts of ethyldimethylsilane were added dropwise thereto, and stirring was continued for 10 min to obtain a mixed solution;

[0136] (2) reacting the mixture obtained in step (1) at 140° C. for 14 h, and then stopping the reaction;

[0137] The obtained reaction solution was placed in a dialysis bag, immersed in deionized water, dialyzed for 60 hours (the deionized water was replaced every 6 hours), and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

[0138] Application Example 1-1 to Application Example 1-12

[0139] Application Examples 1-1 to 1-12 respectively provide a silicon-based nano oil-displacing agent system, the specific composition of which is shown in Table 1 below. The silicon-based nano oil-displacing agent system is obtained by dispersing the sulfonic acid-regulated silicon-based nano oil-displacing agent provided in Example 1 in deionized water.

[0140] Application Example 2-1 to Application Example 10-1

[0141] Application Examples 1-1 to 1-12 respectively provide a silicon-based nano oil-displacing agent system, whose specific composition is shown in Table 1 below. The silicon-based nano oil-displacing agent system is obtained by dispersing the sulfonic acid-regulated silicon-based nano oil-displacing agent provided by Examples 2-1 to 10-1 in deionized water in sequence.

[0142] Application Comparative Example 1-1~Application Comparative Example 1-2

[0143] Application Comparative Example 1-1 to Application Comparative Example 1-2 respectively provide a silicon-based nano oil-displacing agent system, whose specific composition is shown in Table 1 below. The silicon-based nano oil-displacing agent system is obtained by dispersing the sulfonic acid-regulated silicon-based nano oil-displacing agent provided in Comparative Example 1 in deionized water.

[0144] Application Comparative Example 2-1 to Application Comparative Example 3-1

[0145] Comparative Example 2-1 is used to provide an oil-displacing agent system, the specific composition of which is shown in Table 1 below. The silicon-based nano-oil-displacing agent system is obtained by dispersing the oil-displacing agents provided by Comparative Example 2 and Comparative Example 3 in deionized water.

[0146] Application Comparative Example 4-1

[0147] Comparative Example 4-1 is used to provide an oil-displacing agent system, wherein the oil-displacing agent system is deionized water.

[0148] Table 1

[0149]

[0150]

[0151] It should be noted that in Table 1, the concentration of the silicon-based nano oil-displacing agent system is mass concentration.

[0152] (1) Zeta potential and particle size characterization

[0153] The Zeta potential and particle size of the oil displacement agent system used in some of the above application examples and comparative examples were tested using a dynamic light scattering particle size analyzer:

[0154] (2) Evaluation of heat and salt resistance

[0155] The temperature and salt resistance of the oil displacement agents used in the above application examples and comparative examples were evaluated as follows:

[0156] Take 2g of sodium chloride and dissolve it in 97.99g of deionized water to prepare a mineralization degree of 2×10 4 mg / L salt solution, then take 0.01g of oil displacement agent and disperse it in the salt solution and stir evenly to obtain a mixed liquid with an oil displacement agent concentration of 0.01%, and take 20g of the mixed liquid into ampoules respectively, and place the ampoules in an oven at 80℃, 90℃, 100℃, and 110℃ for 72h. The same method is used to prepare a mineralization of 1×10 4 mg / L、3×10 4 mg / L, 4×10 4 mg / L, 6×10 4 mg / L、8×10 4 mg / L, 10×10 4 mg / L, 12×10 4 mg / L, 14×10 4 mg / L, a 0.01% concentration of oil displacement agent mixed liquid, observe whether the mixed liquid settles to determine its temperature and salt resistance, and record the mineralization of the mixed liquid when sedimentation occurs.

[0157] The results of characterizing the particle size of the oil-displacing agent in the oil-displacing agent system provided by Example 1-1 and Comparative Example 1-2 are as follows: Figure 1 and Figure 2 As shown. Figure 1 and Figure 2 It can be seen that the particle size of the oil-displacing agent (silicon-based nano oil-displacing agent provided in Example 1) in the oil-displacing agent system provided in Application Example 1-1 is ≤10nm; the particle size distribution of the oil-displacing agent (silicon dioxide provided in Comparative Example 1) in the oil-displacing agent system provided in Application Comparative Example 1-2 is between 50 and 60nm. The Zeta potential of the oil-displacing agent system provided in Application Example 1-1 and Application Comparative Example 1-2 was tested three times, and the test results are compared as shown in the figure below. Figure 3 As shown by Figure 3 It can be seen that the Zeta potential of the oil displacement agent system provided by Application Example 1-1 is between 35 and 43 mV, and the Zeta potential of the oil displacement agent system provided by Comparative Example 1-2 is between 30 and 37 mV. Figure 1-3 It can be seen that the silicon-based nano oil-displacing agent provided by the present invention has ultra-small particle size and good dispersion stability in deionized water under normal temperature and salt-free conditions.

[0158] The heat and salt resistance performance of the oil-displacing agent used in Application Example 1-1 (silicon-based nano oil-displacing agent provided in Example 1) and the oil-displacing agent used in Application Example 1-2 (silicon dioxide provided in Comparative Example 1) at different temperatures is shown in the figure. Figure 4 As shown. Figure 4 The oil-displacing agent provided by the present invention (the sulfonic acid-regulated silicon-based nano-oil-displacing agent provided in Example 1) has a temperature and salt resistance of 14×10- 4 mg / L, 12×10 4 mg / L、8×10 4 mg / L, 6×10 4 mg / L; while the conventional nano-silica oil displacement agent (silica provided in Comparative Example 1) has poor heat resistance and salt resistance, with a heat resistance and salt resistance of 5×10 at 80°C. 4 mg / L, completely precipitated at 100℃. Figure 4 It can be seen that in the silicon-based nano oil-displacing agent provided by the present invention, sulfonate successfully modifies the surface functional groups of silicon dots, introduces functional groups such as sulfonic acid groups and amide groups on its surface, and significantly improves the temperature and salt resistance of the sulfonic acid-regulated silicon-based nano oil-displacing agent.

[0159] The above performance test results are shown in Table 2 below:

[0160] Table 2

[0161]

[0162] From the above content and the content of Table 1, it can be seen that in the present invention, by designing the raw materials and preparation method of the silicon-based nano oil-displacing agent regulated by sulfonic acid, a silicon-based nano oil-displacing agent with an average particle size of ≤10nm and good stability is prepared, and its Zeta potential is 35.12-40.53mV, and the temperature and salt resistance at 80℃ is ≥12×10 4 mg / L, the heat and salt resistance at 90℃ is ≥8×10 4 mg / L, heat and salt resistance at 100℃≥4×10 4 mg / L, heat and salt resistance at 110℃≥1×10 4 mg / L.

[0163] Compared with Example 1, if the amount of sulfonate used in the preparation of the sulfonic acid-regulated silicon-based nano-oil-displacing agent is too much (Application Example 8-1), the performance of the prepared silicon-based nano-oil-displacing agent is better, but it will cause waste of raw materials; if the amount of sulfonate used in the preparation of the sulfonic acid-regulated silicon-based nano-oil-displacing agent is too little (Application Example 9-1), the temperature and salt resistance of the prepared silicon-based nano-oil-displacing agent system is poor.

[0164] Compared with Example 1, when preparing the sulfonic acid-regulated silicon-based nano-oil-displacing agent, silicon dots are first prepared and then modified (Application Example 10-1), and the preparation process is more complicated.

[0165] Compared with Example 1, if silicon dioxide powder with a larger particle size is used as the oil-displacing agent (Comparative Application Examples 1-2), the temperature and salt resistance of the prepared silicon-based nano-oil-displacing agent system is poor.

[0166] Compared with Example 1, if the composite system of silicon dots and sulfonates is selected as the oil-displacing agent (Comparative Application Example 2-1), the heat and salt resistance of the prepared silicon-based nano oil-displacing agent system is poor.

[0167] Compared with Example 1, if a strong alkaline solution is not used to stop the reaction when preparing the sulfonic acid-regulated silicon-based nano-oil-displacing agent (application of Comparative Example 3-1), the size of the silicon-based nano-oil-displacing agent cannot be accurately controlled, and the particle size of the prepared silicon dioxide is larger, resulting in poor temperature and salt resistance of the silicon-based nano-oil-displacing agent system.

[0168] (3) High temperature and high salt flooding experiment

[0169] A low-permeability outcrop sandstone core with a permeability of 30 mD was taken, and after washing and drying, the core was saturated with brine (8×10 4mg / L NaCl), and then the core is transferred to a core holder, and the simulated oil (viscosity is 20 mPa·s) is saturated by displacement, the displacement flow rate is 0.005 ml / min, the displacement saturation time is 24 h, and the volume of the brine at the outlet is recorded as the saturated oil volume, recorded as V1; the injection rate is set to 0.2 mL / min, the ambient temperature of the high temperature and high pressure displacement device is adjusted to 100 ° C, and the oil displacement agent system provided by the above application example and the application comparison example is used to displace the core until no oil is produced, and the oil production is recorded as V2, and the ratio of the oil production to the saturated oil volume (V2 / V1) is the recovery factor.

[0170] Since the oil-displacing agent nano-silicon dioxide in the comparative examples 1-1 and 1-2 is heated to 100°C and 8×10 4 Obvious precipitation was produced in the 3000 mg / L NaCl environment, and the oil displacement experiment was carried out at room temperature and salt-free conditions.

[0171] The above test results are shown in Table 3 below:

[0172] Table 3

[0173]

[0174]

[0175] From the above content, it can be seen that the size of the sulfonic acid-regulated silicon-based nano-oil-displacing agent provided by the present invention can be precisely controlled, is temperature-resistant and salt-resistant, and can adapt to harsh formation environments. In addition, its synthesis steps are simple, the experimental conditions are easy to control, the reaction process is mild, the cost is low, and the synthesis repeatability is high.

[0176] It can be seen from Application Examples 1-1 to 1-12 of the present invention that with the increase of the content of silicon-based nano-oil-displacing agent regulated by sulfonic acid in the silicon-based nano-oil-displacing agent system, the recovery rate shows a trend of first increasing and then decreasing. This is because, after the low-concentration silicon-based nano-oil-displacing agent is injected into the core, it is adsorbed on the oil-water interface and the core wall at the same time, which reduces the oil-water interfacial tension on the one hand, and improves the roughness of the core wall on the other hand, reducing the flow resistance. In addition, the presence of silicon dots destroys the interaction force between oil and rock, mainly reducing the adhesion force, so that the crude oil in the core is better stripped, so the recovery effect is good; however, as the concentration of the silicon-based nano-oil-displacing agent increases, a large number of silicon dots accumulate in the pores of the core, and there is a phenomenon of blocking the micro-nano pores. Compared with the oil displacement result at low concentration, the flow resistance increases after the high-concentration silicon-based nano-oil-displacing agent is injected, and even the pores are blocked, the crude oil cannot flow, the difficulty of production is increased, and the recovery rate is reduced. This shows that the higher the concentration of the silicon-based nano oil-displacing agent system in the present invention, the better the oil-displacing effect is, and the higher the content of the silicon-based nano oil-displacing agent regulated by sulfonic acid in the silicon-based nano oil-displacing agent system, the higher its cost will be.

[0177] The present invention controls the content of the silicon-based nano oil-displacing agent regulated by sulfonic acid in the silicon-based nano oil-displacing agent system within a specific range, so that the recovery rate of the silicon-based nano oil-displacing agent system prepared is ≥53.77%, specifically 53.77-63.38%.

[0178] It can be seen from Application Example 8-1 that if too much sulfonate is used when preparing the sulfonic acid-regulated silicon-based nano-oil-displacing agent, the recovery rate of the silicon-based nano-oil-displacing agent system will not be significantly improved, and it will cause waste of raw materials; it can be seen from Application Example 9-1 that if too little sulfonate is used when preparing the sulfonic acid-regulated silicon-based nano-oil-displacing agent, the modification of the silicon points by the sulfonate is insufficient, and the recovery rate of the silicon-based nano-oil-displacing agent system obtained thereby is low.

[0179] It can be seen from Application Example 10-1 that when preparing sulfonic acid-regulated silicon-based nano-oil-displacing agent, silicon dots are first prepared and then modified. The preparation process is relatively complicated, and the recovery rate of the silicon-based nano-oil-displacing agent system obtained thereby is also relatively poor.

[0180] It can be seen from Application Comparative Examples 1-1 and 1-2 that if nano-silicon dioxide with a larger particle size is used as an oil displacement agent, the recovery rate of the oil displacement agent system is low under normal temperature and salt-free conditions, and the maximum recovery rate is only 48.39%.

[0181] It can be seen from the application comparative example 2-1 that if the composite system of silicon dots and sodium dodecylbenzene sulfonate is selected as the oil-displacing agent, the recovery rate of the silicon-based nano oil-displacing agent system obtained thereby is relatively low.

[0182] It can be seen from the application comparison example 3-1 that if a strong alkaline solution is not used to stop the reaction when preparing the sulfonic acid-regulated silicon-based nano-oil-displacing agent, the size of the silicon-based nano-oil-displacing agent cannot be accurately controlled, and the particle size of the prepared silicon-based nano-oil-displacing agent is larger, and the recovery rate of the silicon-based nano-oil-displacing agent system obtained thereby is lower.

[0183] It can be seen from the application comparative example 4 that if water is used as an oil displacement agent, in a high temperature and high salt environment, the water flooding recovery rate is only 44.78%, which is relatively low.

[0184] From the above content, it can be seen that in the present invention, the raw materials and preparation method of the silicon-based nano oil-displacing agent regulated by sulfonic acid are designed to prepare a silicon-based nano oil-displacing agent with precisely controllable size, temperature and salt resistance, good stability, and adaptability to harsh formation environments. The present invention provides a silicon-based nano oil-displacing agent regulated by sulfonic acid, which has simple synthesis steps, easy-to-control experimental conditions, mild reaction process, low cost and high synthetic repeatability. At the same time, the present invention designs the content of the silicon-based nano oil-displacing agent regulated by sulfonic acid in the silicon-based nano oil-displacing agent system to obtain a silicon-based nano oil-displacing agent system with a higher recovery rate.

[0185] The applicant declares that the present invention illustrates the detailed process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sulfonic acid-regulated silicon-based nano oil-displacing agent, characterized in that: The raw materials for preparing the silicon-based nano oil-displacing agent include the following components in parts by weight: 2 to 10 parts of silane coupling agent, 0.05 to 5 parts of sulfonate, and 2 to 20 parts of strong base compound.

2. The sulfonic acid-regulated silicon-based nano oil-displacing agent according to claim 1, characterized in that: The silane coupling agent is selected from any one or a combination of at least two of ethyldimethylsilane, tris(trimethylsiloxy)silane or vinyltris(2-methoxyethoxy)silane; Preferably, the sulfonic acid salt is selected from any one of sodium dodecylbenzenesulfonate, p-aminobenzenesulfonic acid or sodium p-aminobenzenesulfonate, or a combination of at least two thereof.

3. The sulfonic acid-regulated silicon-based nano oil-displacing agent according to claim 1 or 2, characterized in that: The strong base compound is selected from sodium hydroxide and / or potassium hydroxide; Preferably, the raw materials for preparing the sulfonic acid-regulated silicon-based nano oil-displacing agent further include 100 to 300 parts by weight of solvent A; Preferably, the solvent comprises water.

4. The sulfonic acid-regulated silicon-based nano oil-displacing agent according to any one of claims 1 to 3, characterized in that: The average particle size of the silicon-based nano oil-displacing agent is ≤10 nm.

5. A method for preparing a sulfonic acid-regulated silicon-based nano oil-displacing agent according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: (1) dissolving a strong base compound in part of solvent A to obtain a strong base solution; Dissolving the sulfonate in the remaining solvent A, adding a silane coupling agent dropwise thereto, and mixing evenly to obtain a mixed solution; (2) After the mixed solution obtained in step (1) is reacted, a strong alkaline solution is added thereto to stop the reaction, thereby obtaining the sulfonic acid-regulated silicon-based nano oil-displacing agent.

6. The preparation method according to claim 5, characterized in that: The mass concentration of the strong alkaline solution is 2 to 20%; Preferably, the method of dissolving the sulfonate in the solvent comprises stirring; Preferably, the stirring time is 5 to 30 minutes, and the stirring speed is 150 to 300 rpm; Preferably, the method of adding the silane coupling agent is dropwise addition; Preferably, the method of adding the silane coupling agent and mixing uniformly comprises stirring; Preferably, the stirring time is 5 to 10 minutes, and the stirring speed is 150 to 300 rpm.

7. The preparation method according to claim 5 or 6, characterized in that: The reaction temperature is 120-180°C and the reaction time is 4-20h; Preferably, the reaction is carried out under stirring conditions, and the stirring speed is 150 to 300 rpm; Preferably, after adding the strong alkaline solution, the pH of the reaction system is 6 to 8; Preferably, the step of post-treatment is further included after the stopping reaction; Preferably, the post-treatment method comprises: placing the reaction solution in a dialysis bag for dialysis and freeze drying; Preferably, the dialysate used in the dialysis is deionized water; Preferably, the dialysis time is 48 to 72 hours.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The preparation method specifically comprises the following steps: (1) dissolving a strong alkaline compound in a portion of solvent A to obtain a strong alkaline solution having a mass concentration of 2 to 20%; Under the condition of a rotation speed of 200 rpm, the sulfonate is placed in the remaining solvent A, and stirred for 5 to 30 minutes to dissolve the sulfonate, and then a silane coupling agent is added dropwise thereto, and stirring is continued for 5 to 10 minutes to obtain a mixed solution; (2) reacting the mixed solution obtained in step (1) at 120 to 180° C. for 4 to 20 hours, adding a strong alkaline solution until the pH of the reaction system is 6 to 8, and stopping the reaction; The obtained reaction solution is placed in a dialysis bag, immersed in deionized water, dialyzed for 48 to 72 hours, and then freeze-dried to obtain the sulfonic acid-regulated silicon-based nano-oil-displacing agent.

9. A silicon-based nano oil-displacing agent system, characterized in that: The silicon-based nano oil-displacing agent system comprises the sulfonic acid-regulated silicon-based nano oil-displacing agent according to any one of claims 1 to 4 and solvent B; Preferably, the solvent B comprises water; Preferably, the mass concentration of the silicon-based nano-oil-displacing agent in the sulfonic acid-regulated silicon-based nano-oil-displacing agent system is 0.01-0.5%.

10. An application of the silicon-based nano oil-displacing agent system as claimed in claim 9, characterized in that: The silicon-based nano oil-displacing agent system is used for recovering low-permeability oil reservoirs; Preferably, the permeability of the low permeability reservoir is 10 to 500 mD; Preferably, the silicon-based nano oil-displacing agent system is used for recovery temperatures below 100°C and mineralization ≤8×10 4 mg / L oil reservoir; Preferably, the silicon-based nano oil-displacing agent system is used to recover oil reservoirs with a crude oil viscosity of ≤6000 mPa·s.

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