A low-temperature slow-release anti-swelling system, preparation method and application

Abstract

The present invention relates to the technical field of the preparation of clay anti-swelling agents for oil fields, and in particular to a low-temperature slow-release anti-swelling system, a preparation method and an application, which include a benzyl-quaternary ammonium salt anti-swelling agent, an oil-phase solvent and a non-ionic surfactant solution; wherein, the mass ratio of the benzyl-quaternary ammonium salt anti-swelling agent to the oil-phase solvent is (1-1.5):(1-1.5); the mass ratio of the sum of the benzyl-quaternary ammonium salt anti-swelling agent and the oil-phase solvent to the non-ionic surfactant solution is (1-1.5):(1-1.5). By utilizing the cloud point characteristic of the non-ionic surfactant, under high-temperature conditions, the anti-swelling agent is mainly in the oil phase and it is difficult to combine with clay; under low-temperature conditions, under the emulsification of the non-ionic surfactant, the anti-swelling agent contacts with the water phase more fully, and the anti-swelling agent is released into the water phase to combine with the clay, achieving the effect that the anti-swelling agent is not released at high temperature, i.e., at the wellhead end, and is released at low temperature, i.e., at the distal reservoir. It solves the problem that the anti-swelling effect is not ideal due to the poor temperature resistance of the organic anti-swelling agent, and it is difficult to play an anti-swelling role in the distal reservoir.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of clay anti-swelling agents for oil fields, and specifically to a low-temperature slow-release anti-swelling system, a preparation method and an application thereof. Background Art

[0002] Clay minerals are widely present in oil reservoir formations. For water-sensitive reservoirs containing clay minerals, if appropriate measures are not taken, the clay minerals will undergo hydration swelling, dispersion and migration, which are extremely likely to block the oil layer passages, damage the formation, cause a decrease in permeability, and seriously affect the oil recovery efficiency. Today, with the shortage of oil resources, in order to achieve stable and high production of oil and gas fields, clay stabilizers, namely anti-swelling agents, are widely used. Common anti-swelling agents mainly include: inorganic salt anti-swelling agents and organic anti-swelling agents.

[0003] Heavy oil, that is, high-viscosity crude oil, has a large flow resistance and even cannot flow, so it is difficult to develop it using conventional production techniques. With the gradual reduction of crude oil resources, the development of heavy oil has been accelerated. Through research, it has been found that heavy oil is extremely sensitive to temperature. For every 10°C increase in temperature, the viscosity approximately drops by half. At present, the steam injection thermal recovery technique has effectively developed a number of heavy oil fields, but the highest recovery rate of the steam injection thermal recovery technique only reaches 30%. To address the problem of low recovery rate, the subcritical injection and production process has been adopted, which has further improved the recovery rate. However, the steam injected in this process is already close to the critical point, and the wellhead temperature reaches about 300°C. Since the inorganic salt anti-swelling agent can only be used at about 80°C and has a short action time, it is difficult to achieve effective anti-swelling; in contrast, the organic quaternary ammonium salt anti-swelling agent has better temperature resistance, but the effect is not ideal above 200°C. At the same time, the organic anti-swelling agent is easily adsorbed at the inlet end, so it is difficult to play an anti-swelling role in the distal oil reservoir. Summary of the Invention

[0004] Aiming at the problems in the prior art that the anti-swelling effect is not ideal due to the poor temperature resistance of the organic anti-swelling agent and it is difficult to play an anti-swelling role in the distal oil reservoir, the present invention provides a low-temperature slow-release anti-swelling system, a preparation method and an application thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a low-temperature slow-release anti-swelling system, which includes a benzyl-quaternary ammonium salt anti-swelling agent, an oil-phase solvent and a non-ionic surfactant solution; wherein, the mass ratio of the benzyl-quaternary ammonium salt anti-swelling agent to the oil-phase solvent is (1-1.5):(1-1.5); the mass ratio of the sum of the benzyl-quaternary ammonium salt anti-swelling agent and the oil-phase solvent to the non-ionic surfactant solution is (1-1.5):(1-1.5).

[0007] Preferably, the oil-phase solvent is toluene.

[0008] Preferably, the non-ionic surfactant solution is a benzisothiazolinone solution, a morpholine solution, a polyethylene glycol solution or a nonylphenol polyoxyethylene ether solution.

[0009] Preferably, the mass concentration of the non-ionic surfactant solution is 1% to 2%.

[0010] The preparation method of the low-temperature slow-release anti-swelling system as described above includes the following steps:

[0011] Prepare a benzyl-quaternary ammonium salt anti-swelling agent;

[0012] Use the benzyl-quaternary ammonium salt anti-swelling agent to prepare an oil phase containing the anti-swelling agent;

[0013] Prepare a non-ionic surfactant solution;

[0014] Use the non-ionic surfactant solution and the oil phase containing the anti-swelling agent to prepare a low-temperature slow-release anti-swelling body.

[0015] Preferably, the method for preparing the benzyl-quaternary ammonium salt anti-swelling agent is as follows:

[0016] Benzyl chloride reacts with piperidine to form an intermediate product;

[0017] Add methanol and dimethyl carbonate to the intermediate product, and heat and react to obtain a benzyl-quaternary ammonium salt anti-swelling agent.

[0018] Preferably, the molar ratio of benzyl chloride to piperidine is (1.5 - 1):(1.5 - 1); the mass ratio of methanol to the intermediate product is (1 - 1.5):(1 - 1.5); the molar ratio of dimethyl carbonate to the intermediate product is (1 - 1.5):(1 - 1.5).

[0019] Preferably, the reaction conditions of benzyl chloride and piperidine are: under the water bath condition of 80°C to 100°C, react for 1h to 2h.

[0020] Preferably, the temperature of the heating reaction is 150°C to 170°C, and the reaction time is 20h to 24h.

[0021] The application of the low-temperature slow-release anti-swelling system as described above in oil reservoir exploitation.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] A low-temperature slow-release swelling prevention system of the present invention comprises a benzyl-quaternary ammonium salt swelling prevention agent, an oil-phase solvent and a non-ionic surfactant solution; wherein, the mass ratio of the benzyl-quaternary ammonium salt swelling prevention agent to the oil-phase solvent is (1-1.5):(1-1.5); the mass ratio of the sum of the benzyl-quaternary ammonium salt swelling prevention agent and the oil-phase solvent to the non-ionic surfactant solution is (1-1.5):(1-1.5). First of all, this low-temperature slow-release swelling prevention system does not react prematurely at the wellhead high temperature below 300°C, ensuring that it can reach the bottom formation to play the role of swelling prevention, and significantly improving the temperature resistance of the swelling prevention agent. Secondly, this low-temperature slow-release swelling prevention system utilizes the property of the cloud point of the non-ionic surfactant. Under high-temperature conditions, the swelling prevention agent is mainly in the oil phase and it is difficult to combine with clay; under low-temperature conditions, under the emulsification of the non-ionic surfactant, the swelling prevention agent is more fully in contact with the water phase, and the swelling prevention agent is released into the water phase to combine with the clay to achieve the swelling prevention effect. Through the above mechanism, the swelling prevention agent is not released at high temperature, that is, at the wellhead end, and is released at low temperature, that is, at the distal reservoir. The low-temperature triggered release characteristic of the swelling prevention agent is realized, effectively solving the swelling prevention problem in steam thermal recovery and subcritical injection production. Finally, in the structural design of this swelling prevention agent, a benzyl group is introduced, and the prepared bicyclic quaternary ammonium salt structure can ensure that at high temperature, the swelling prevention agent preferentially enters the oil phase, and under the action of the non-ionic surfactant at low temperature, it can achieve the effect of releasing from the oil phase to the water phase.

[0024] By selecting non-ionic surfactants with different structures, the system can be made suitable for different use temperatures through the cloud point.

[0025] The present invention also provides a preparation method of the low-temperature slow-release swelling prevention system as described above. This method prepares a benzyl-quaternary ammonium salt swelling prevention agent; uses the benzyl-quaternary ammonium salt swelling prevention agent to prepare an oil phase containing the swelling prevention agent; prepares a non-ionic surfactant solution; finally, uses the non-ionic surfactant solution and the oil phase containing the swelling prevention agent to successfully prepare a low-temperature slow-release swelling prevention body containing a bicyclic quaternary ammonium salt structure. The preparation method is simple and the system has strong applicability.

[0026] The present invention also provides an application of the low-temperature slow-release swelling prevention system as described above in oil reservoir exploitation. It realizes the swelling prevention effect at the distal oil reservoir and improves the oil reservoir recovery rate. Description of the Drawings

[0027] Figure 1 It is a schematic flow chart of the preparation method of a low-temperature slow-release swelling prevention system of the present invention.

[0028] Figure 2 It is a flow chart of the preparation method of the benzyl-quaternary ammonium salt swelling prevention agent in a low-temperature slow-release swelling prevention system of the present invention.

[0029] Figure 3 It is the nuclear magnetic resonance hydrogen spectrum of the low-temperature slow-release swelling prevention system prepared in Example 1 of the present invention.

[0030] Figure 4 This is the graph showing the variation of the swelling prevention rate of the low-temperature sustained-release swelling prevention system prepared in Example 1 of the present invention with temperature. Detailed implementation manners

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0033] It should be noted that like reference numerals and letters denote like items in the following figures. Therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

[0034] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the product of the invention is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, terms such as "first", "second", etc. are only used for descriptive distinction and cannot be construed as indicating or implying relative importance.

[0035] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0036] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if the terms "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0037] The following further elaborates on the present invention with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0038] The present invention discloses a low-temperature slow-release anti-swelling system, which includes a benzyl-quaternary ammonium salt anti-swelling agent, an oil-phase solvent, and a non-ionic surfactant solution with a mass concentration of 1% - 2%; wherein, the mass ratio of the benzyl-quaternary ammonium salt anti-swelling agent to the oil-phase solvent is (1 - 1.5):(1 - 1.5); the mass ratio of the sum of the benzyl-quaternary ammonium salt anti-swelling agent and the oil-phase solvent to the non-ionic surfactant solution is (1 - 1.5):(1 - 1.5); wherein, the oil-phase solvent is toluene. The non-ionic surfactant solution is a benzisothiazolinone solution, a morpholine solution, a polyethylene glycol solution, or a nonylphenol polyoxyethylene ether solution.

[0039] See Figure 1 , the present invention also provides a preparation method of the above low-temperature slow-release anti-swelling system, which includes the following steps:

[0040] S1: Prepare the benzyl-quaternary ammonium salt anti-swelling agent, see Figure 2 , specifically:

[0041] S1.1: React benzyl chloride with piperidine to generate an intermediate product; wherein, the molar ratio of benzyl chloride to piperidine is (1.5 - 1):(1.5 - 1); the reaction conditions of benzyl chloride and piperidine are: under the water bath condition of 80°C - 100°C, react for 1h - 2h;

[0042] S1.2: Add methanol and dimethyl carbonate to the intermediate product and heat to react to obtain the benzyl-quaternary ammonium salt anti-swelling agent; wherein, the mass ratio of methanol to the intermediate product is (1 - 1.5):(1 - 1.5); the molar ratio of dimethyl carbonate to the intermediate product is (1 - 1.5):(1 - 1.5), the temperature of the heating reaction is 150°C - 170°C, and the reaction time is 20h - 24h;

[0043] The preparation principle of the benzyl-quaternary ammonium salt anti-swelling agent is:

[0044]

[0045]

[0046] S2: Prepare an oil phase containing an anti-swelling agent using a benzyl-quaternary ammonium salt anti-swelling agent.

[0047] S3: Prepare a non-ionic surfactant solution.

[0048] S4: Prepare a low-temperature sustained-release anti-swelling body using the non-ionic surfactant solution and the oil phase containing the anti-swelling agent.

[0049] Application of the low-temperature sustained-release anti-swelling system as described above in oil reservoir exploitation. Achieve anti-swelling effect at the distal oil reservoir and improve oil reservoir recovery rate.

[0050] In the following examples, an isothiazolinone solution is used as the non-ionic surfactant. The cloud point of the isothiazolinone solution is 180°C. During the actual exploitation process, the type of non-ionic surfactant can be adjusted according to actual needs to reach the required temperature resistance. The cloud point of morpholine is 150°C, the cloud point of polyethylene glycol is 120°C, and the cloud point of nonylphenol polyoxyethylene ether is 90°C. Different non-ionic surfactants have different cloud points, which enables the entire anti-swelling system to be used in oil wells with different thermal recovery temperatures and adjusted according to actual needs. In this invention, the isothiazolinone solution is taken as an example and is applicable to oil wells with a wellhead temperature of about 300°C. However, this is only for further illustration and does not determine that the specific implementation of this invention is limited thereto.

[0051] Example 1

[0052] Add 100 g of benzyl chloride and 79 g of piperidine to a reactor, react at 80°C in a water bath for 1 h to obtain an intermediate product, i.e., benzylpiperidine. Using 142 g of methanol as a solvent, react 142 g of benzylpiperidine with 90 g of dimethyl carbonate at 150°C for 24 h to obtain a quaternary ammonium salt anti-swelling agent containing benzyl. Using toluene as the oil phase solvent, mix 156 g of the quaternary ammonium salt anti-swelling agent with 156 g of the oil phase solvent to obtain an oil phase containing the quaternary ammonium salt anti-swelling agent. Mix 312 g of the oil phase containing the quaternary ammonium salt anti-swelling agent with 312 g of a 2% mass concentration non-ionic surfactant benzisothiazolinone solution evenly to prepare a low-temperature release anti-swelling system.

[0053] Example 2

[0054] 150 g of benzyl chloride and 118 g of piperidine were added to a reactor and reacted at 80 °C in a water bath for 1 h to obtain an intermediate product, namely benzylpiperidine; using 213 g of methanol as a solvent, 213 g of benzylpiperidine and 135 g of dimethyl carbonate were reacted at 150 °C for 24 h to obtain a quaternary ammonium salt swelling inhibitor containing benzyl. Using toluene as an oil-phase solvent, 234 g of the quaternary ammonium salt swelling inhibitor was mixed with 234 g of the oil-phase solvent to obtain an oil phase containing the quaternary ammonium salt swelling inhibitor. 468 g of the oil phase containing the quaternary ammonium salt swelling inhibitor was mixed evenly with 468 g of a 2% mass concentration of the nonionic surfactant benzisothiazolinone solution to prepare a low-temperature release swelling prevention system.

[0055] Example 3

[0056] 120 g of benzyl chloride and 90 g of piperidine were added to a reactor and reacted at 85 °C in a water bath for 1 h to obtain an intermediate product, namely benzylpiperidine; using 180 g of methanol as a solvent, 180 g of benzylpiperidine and 110 g of dimethyl carbonate were reacted at 150 °C for 24 h to obtain a quaternary ammonium salt swelling inhibitor containing benzyl. Using toluene as an oil-phase solvent, 200 g of the quaternary ammonium salt swelling inhibitor was mixed with 200 g of the oil-phase solvent to obtain an oil phase containing the quaternary ammonium salt swelling inhibitor. 400 g of the oil phase containing the quaternary ammonium salt swelling inhibitor was mixed evenly with 400 g of a 2% mass concentration of the nonionic surfactant benzisothiazolinone solution to prepare a low-temperature release swelling prevention system.

[0057] Example 4

[0058] 100 g of benzyl chloride and 79 g of piperidine were added to a reactor and reacted at 80 °C in a water bath for 2 h to obtain an intermediate product, namely benzylpiperidine; using 142 g of methanol as a solvent, 142 g of benzylpiperidine and 90 g of dimethyl carbonate were reacted at 160 °C for 20 h to obtain a quaternary ammonium salt swelling inhibitor containing benzyl. Using toluene as an oil-phase solvent, 156 g of the quaternary ammonium salt swelling inhibitor was mixed with 156 g of the oil-phase solvent to obtain an oil phase containing the quaternary ammonium salt swelling inhibitor. 312 g of the oil phase containing the quaternary ammonium salt swelling inhibitor was mixed evenly with 312 g of a 2% mass concentration of the nonionic surfactant benzisothiazolinone solution to prepare a low-temperature release swelling prevention system.

[0059] Example 5

[0060] 100 g of benzyl chloride and 79 g of piperidine were added to a reactor and reacted at 86 °C in a water bath for 2 h to obtain an intermediate product, namely benzylpiperidine. Using 142 g of methanol as a solvent, 142 g of benzylpiperidine and 90 g of dimethyl carbonate were reacted at 150 °C for 22 h to obtain a quaternary ammonium salt swelling inhibitor containing benzyl. Using toluene as an oil-phase solvent, 156 g of the quaternary ammonium salt swelling inhibitor was mixed with 156 g of the oil-phase solvent to obtain an oil phase containing the quaternary ammonium salt swelling inhibitor. 312 g of the oil phase containing the quaternary ammonium salt swelling inhibitor was mixed evenly with 312 g of a 1.8% mass concentration of the non-ionic surfactant benzisothiazolinone solution to prepare a low-temperature release swelling inhibition system.

[0061] Example 6

[0062] 100 g of benzyl chloride and 79 g of piperidine were added to a reactor and reacted at 90 °C in a water bath for 1 h to obtain an intermediate product, namely benzylpiperidine. Using 142 g of methanol as a solvent, 142 g of benzylpiperidine and 90 g of dimethyl carbonate were reacted at 160 °C for 24 h to obtain a quaternary ammonium salt swelling inhibitor containing benzyl. Using toluene as an oil-phase solvent, 156 g of the quaternary ammonium salt swelling inhibitor was mixed with 156 g of the oil-phase solvent to obtain an oil phase containing the quaternary ammonium salt swelling inhibitor. 312 g of the oil phase containing the quaternary ammonium salt swelling inhibitor was mixed evenly with 312 g of a 2% mass concentration of the non-ionic surfactant benzisothiazolinone solution to prepare a low-temperature release swelling inhibition system.

[0063] Example 7

[0064] 100 g of benzyl chloride and 79 g of piperidine were added to a reactor and reacted at 100 °C in a water bath for 1 h to obtain an intermediate product, namely benzylpiperidine. Using 142 g of methanol as a solvent, 142 g of benzylpiperidine and 90 g of dimethyl carbonate were reacted at 150 °C for 24 h to obtain a quaternary ammonium salt swelling inhibitor containing benzyl. Using toluene as an oil-phase solvent, 156 g of the quaternary ammonium salt swelling inhibitor was mixed with 156 g of the oil-phase solvent to obtain an oil phase containing the quaternary ammonium salt swelling inhibitor. 312 g of the oil phase containing the quaternary ammonium salt swelling inhibitor was mixed evenly with 312 g of a 2% mass concentration of the non-ionic surfactant benzisothiazolinone solution to prepare a low-temperature release swelling inhibition system.

[0065] See Figure 3 , in order to characterize the structural characteristics of the benzyl swelling inhibitor, a nuclear magnetic resonance hydrogen spectrum test was carried out on the swelling inhibition system prepared in Example 1, and the results are as follows:

[0066] 1 H NMR (300 MHz, DMSO): δ 7.25 (m, H), 7.22 (m, H), 7.16 (m, H), 4.50 (s, H), 3.30 (s, H), 3.22 (m, H), 1.71 (m, H), 1.60 (m, H) ppm.

[0067] It can be seen from the nuclear magnetic data that the swelling prevention system with the target structure has been successfully prepared in the present invention.

[0068] In order to characterize the application performance of the low-temperature slow-release swelling prevention system, the following tests are carried out on it:

[0069] First, refer to the centrifugation method in SY / T591-2016 "Performance Evaluation Method for Clay Stabilizers Used in Oil and Gas Field Fracturing Acidizing and Water Injection" to test the swelling prevention rate of the swelling prevention systems synthesized in Examples 1-7:

[0070] Weigh 0.50 g of sodium bentonite powder, accurate to 0.01 g, place it in the reaction kettle of a high-temperature and high-pressure closed reactor, add 10 ml of the low-temperature slow-release swelling prevention system prepared in Example 1, shake well and mix evenly, and place them in a constant-temperature drying oven at temperatures of 150 °C, 170 °C, 190 °C, 210 °C, 230 °C, 250 °C, 270 °C, 290 °C and 310 °C respectively, stand for 24 h, naturally cool to room temperature, and take out. Transfer the clay mixture in the high-temperature and high-pressure closed reactor to a centrifuge tube and put it into a centrifuge. The centrifuge centrifuges at 1500 r / min for 15 min. Obtain the swelling volume V1 of the bentonite;

[0071] Use experimental water to replace the swelling prevention agent solution, and measure the swelling volume V2 of sodium bentonite in experimental water;

[0072] Use kerosene to replace the swelling prevention rate solution, and measure the swelling volume V0 of sodium bentonite in kerosene;

[0073] The swelling prevention rate is calculated according to the following method: that is, B1 = (V2 - V1) / (V2 - V0) × 100%; draw a curve graph of the swelling prevention rate changing with temperature, see Figure 4 , it can be seen that in the high-temperature environment of 230 °C to 300 °C, the prepared swelling prevention system has almost no swelling prevention effect, which proves that due to the loss of emulsification effect of non-ionic surfactants under high-temperature conditions, the swelling prevention agent is mainly in the oil phase and is hardly released at high temperatures. At low temperatures of 150 °C to 170 °C, the swelling prevention effect of the synthesized swelling prevention system reaches more than 90%, which proves that at low temperatures, under the emulsification effect of non-ionic surfactants, the swelling prevention agent contacts the water phase more fully, and the swelling prevention agent is released into the water phase and combines with the clay to achieve the swelling prevention effect. The effect that the swelling prevention agent is not released at high temperatures, i.e., the wellhead end, and is released at low temperatures, i.e., the distal reservoir, is achieved.

[0074] Mineralization tolerance test:

[0075] Prepare water with salinities of 20,000, 40,000, 60,000, 80,000 and 100,000 using distilled water to simulate conditions of different salinities. Take 10 ml of the swelling prevention system from Example 2 and 0.50 g of bentonite and place them in a high-temperature and high-pressure closed reaction kettle. Shake well and mix thoroughly, then place it in a constant-temperature drying oven at 170 °C for 2 h, and measure its swelling prevention rate by the centrifugation method. The results are shown in the following table:

[0076]

[0077] It can be seen that under the condition of 170 °C, as the salinity increases, the swelling prevention rate of the swelling prevention system decreases somewhat, but when the salinity is 100,000, the swelling prevention rate can still reach 80%.

[0078] Water wash resistance test:

[0079] Weigh 0.50 g of bentonite powder, accurate to 0.01 g, and place it in a high-temperature and high-pressure closed reaction kettle. Shake well and mix thoroughly, then add 10 ml of the swelling prevention system prepared in any one of Examples 1-7 and shake well and mix thoroughly. Place it in a constant-temperature drying oven at 170 °C for 2 h, centrifuge at 1500 r / min for 15 min, and calculate the swelling volume V1 of the bentonite; discard the supernatant in the centrifuge tube, add experimental water to 10 ml, shake well and let it stand for 2 h, centrifuge at 1500 r / min for 15 min, and repeat this operation 2 times to obtain the swelling volume V3; the calculation method of the water wash resistance rate is: N = V1 / V3 × 100%:

[0080] Example Anti-swelling rate after water washing (%) Example 1 90.0 Example 2 89.3 Example 3 87.1 Example 4 86.4 Example 5 89.1 Example 6 84.3 Example 7 83.6

[0081] It can be seen that the water wash resistance of the prepared swelling prevention system is all higher than 83%, indicating that the synthesized swelling prevention system can form a tight adsorption with the clay, achieving good water wash resistance.

[0082] In summary, the present invention provides a low-temperature slow-release swelling prevention system, a preparation method and an application. The prepared low-temperature slow-release swelling prevention system utilizes the property of the cloud point of non-ionic surfactants. Under high-temperature conditions, the swelling prevention agent is mainly in the oil phase and it is difficult to combine with clay; under low-temperature conditions, under the emulsification of non-ionic surfactants, the swelling prevention agent is in more sufficient contact with the water phase, and the swelling prevention agent is released into the water phase to combine with the clay, achieving the swelling prevention effect. Through the above mechanism, the swelling prevention agent is not released at the high-temperature wellhead end and is released at the low-temperature distal oil reservoir. The low-temperature triggered release characteristic of the swelling prevention agent is realized, effectively solving the swelling prevention problem in steam thermal recovery and subcritical injection-production.

[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the technical solutions of the present invention. Those skilled in the art should understand that without departing from the spirit and principle of the present invention, several simple modifications and substitutions can be made to the technical solutions, and these modifications and substitutions also fall within the protection scope covered by the claims.

Claims

1. A sustained-release swelling prevention system, characterized in that, It includes a benzyl-quaternary ammonium salt swelling inhibitor, an oil-phase solvent, and a non-ionic surfactant solution; wherein, the mass ratio of the benzyl-quaternary ammonium salt swelling inhibitor to the oil-phase solvent is (1 to 1.5):(1 to 1.5); the mass ratio of the sum of the benzyl-quaternary ammonium salt swelling inhibitor and the oil-phase solvent to the non-ionic surfactant solution is (1 to 1.5):(1 to 1.5); wherein, the oil-phase solvent is toluene; the non-ionic surfactant solution is a polyethylene glycol solution or a nonylphenol polyoxyethylene ether solution; The preparation method of the benzyl-quaternary ammonium salt swelling inhibitor is as follows: Benzyl chloride reacts with piperidine to form an intermediate product; Methanol and dimethyl carbonate are added to the intermediate product, and heated for reaction to obtain the benzyl-quaternary ammonium salt swelling inhibitor.

2. The sustained-release anti-swelling system according to claim 1, wherein The mass concentration of the non-ionic surfactant solution is 1% to 2%.

3. The preparation method of the sustained-release anti-swelling system according to claim 1 or 2, characterized in that, It includes the following steps: Prepare the benzyl-quaternary ammonium salt swelling inhibitor; Use the benzyl-quaternary ammonium salt swelling inhibitor to prepare an oil phase containing the swelling inhibitor; Prepare the non-ionic surfactant solution; Use the non-ionic surfactant solution and the oil phase containing the swelling inhibitor to prepare a sustained-release swelling prevention body.

4. The preparation method of the sustained-release anti-swelling system according to claim 3, characterized in that, The method for preparing the benzyl-quaternary ammonium salt swelling inhibitor is as follows: Benzyl chloride reacts with piperidine to form an intermediate product; Methanol and dimethyl carbonate are added to the intermediate product, and heated for reaction to obtain the benzyl-quaternary ammonium salt swelling inhibitor.

5. The preparation method of the sustained-release anti-swelling system according to claim 4, characterized in that, The molar ratio of benzyl chloride to piperidine is (1.5 to 1):(1.5 to 1); the mass ratio of methanol to the intermediate product is (1 to 1.5):(1 to 1.5); the molar ratio of dimethyl carbonate to the intermediate product is (1 to 1.5):(1 to 1.5).

6. The preparation method of the sustained-release anti-swelling system according to claim 4, characterized in that, The conditions for the reaction of benzyl chloride and piperidine are: under a water bath condition of 80°C to 100°C, react for 1 h to 2 h.

7. The preparation method of the sustained-release anti-swelling system according to claim 4, characterized in that, The temperature of the heating reaction is 150°C to 170°C, and the reaction time is 20 h to 24 h.

8. The application of the sustained-release swelling prevention system according to claim 1 or 2 in oil reservoir exploitation.

Images