Functionalized ionic liquid clay stabilizer and preparation method thereof

Abstract

The invention discloses a functionalized ionic liquid clay stabilizer and a preparation method thereof, and belongs to the technical field of oilfield chemistry. The functionalized ionic liquid clay stabilizer is prepared from biquaternary ammonium salt in a formula 1 and a hydrogen bond donor, the structural formula of the biquaternary ammonium salt in the formula 1 is shown in the specification, and R is selected from one or two of C1-C16 alkyl, hydroxyethyl, hydroxypropyl or aryl; x1 and X2 are selected from one or two of chlorine, bromine, fluorine or iodine; n is an integer greater than or equal to 2. The functionalized ionic liquid clay stabilizer is high in charge density, remarkable in anti-swelling effect, high in washing resistance, good in long-term effect and high in temperature resistance, and can be used for high-temperature and ultrahigh-temperature reservoirs and low-permeability and ultra-low-permeability reservoirs. Meanwhile, the functionalized ionic liquid clay stabilizer has small influence on the performance of the fracturing fluid, does not influence the sand-carrying performance of the fracturing fluid, and can be used for hydraulic fracturing.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to a functionalized ionic liquid clay stabilizer and a preparation method thereof. Background Art

[0002] During oilfield waterflooding and acid fracturing, clay minerals (such as kaolinite, montmorillonite, illite, and chlorite) in the formation swell, disperse, and migrate when exposed to influent water or water-based substances. This can even clog pore throats, reducing formation permeability and causing serious damage to low-permeability reservoirs. Therefore, clay stabilizers are often added to the inflowing fluid to prevent hydration, swelling, and migration of the clay, thereby protecting the reservoir. Generally, the surface of clay particles is negatively charged, while the cations in the clay stabilizer are positively charged. The electrostatic attraction between the two creates a strong adsorption effect, slowing the penetration of water molecules and preventing the hydration and swelling of the clay minerals, thus inhibiting the hydration and swelling of the clay minerals.

[0003] Early use of inorganic salts such as KCl and NH₄Cl as clay stabilizers was associated with high dosages and a certain impact on wellbore fluid properties. Hydroxyaluminum or zirconium hydroxylates were used in the 1960s and 1970s, but these stabilizers presented challenges such as poor heat and acid resistance. In recent years, the most commonly used clay stabilizers have been quaternary ammonium surfactants, polyamines, and polyquaterniums. The above clay stabilizers all have good anti-swelling effects, but there are also certain problems: the production process of polyamine clay stabilizers is relatively complex, their water washability is poor, and their effective period is short; polyquaternary ammonium salt clay stabilizers have a large molecular weight and are not suitable for low permeability reservoirs, which will aggravate the damage to the permeability of low permeability reservoirs; quaternary ammonium salt surfactants will make the reservoir oil-wet, thereby reducing the oil phase permeability, which is not conducive to crude oil extraction; in addition, the above-mentioned types of clay stabilizers have poor compatibility with fracturing fluids, which will greatly reduce the sand carrying performance of the fracturing fluid and increase the difficulty of adding sand during fracturing construction; in some high-temperature and ultra-high-temperature oil reservoir environments, conventional clay stabilizers will lose stability due to excessively high temperatures and cannot effectively inhibit clay hydration expansion, limiting their application in high-temperature and ultra-high-temperature oil reservoirs.

[0004] Therefore, it is of great practical significance to develop clay stabilizers with excellent performance to reduce formation damage, extend the service life of oil and gas wells, and achieve sustainable development of oil and gas resources. Summary of the Invention

[0005] In response to the problems raised in the background technology, the main purpose of the present invention is to provide a functionalized ionic liquid clay stabilizer and a preparation method thereof. The clay stabilizer of the present invention is an ionic liquid constructed from small molecule compounds, has a small molecular weight, high charge density, strong heat and water resistance, significant anti-swelling effect, good compatibility with fracturing fluid, and little effect on the performance of the fracturing fluid.

[0006] In order to achieve the above object, the present invention provides a functionalized ionic liquid clay stabilizer, which is prepared from a diquaternary ammonium salt of Formula 1 and a hydrogen bond donor, wherein the structural formula of the diquaternary ammonium salt is: Formula 1; Among them, R is selected from C1~C 16 One or two of alkyl, hydroxyethyl, hydroxypropyl or aromatic groups; X1 and X2 are one or two of chlorine, bromine, fluorine or iodine; n is an integer ≥2.

[0007] Furthermore, the hydrogen bond donor is selected from one or more of urea, thiourea, ethylene glycol or glycerol.

[0008] Furthermore, n is an integer from 2 to 6.

[0009] Another aspect of the present invention provides a method for preparing a functionalized ionic liquid clay stabilizer, comprising the following steps: A tertiary amine compound, an α,ω-dihalogenated alkane, and a hydrogen bond donor are mixed and reacted, wherein the tertiary amine compound and the α,ω-dihalogenated alkane react to generate a diquaternary ammonium salt of Formula 1, and the diquaternary ammonium salt reacts with the hydrogen bond donor to obtain the functionalized ionic liquid clay stabilizer; Wherein, the structural formula of described diquaternary ammonium salt is: Formula 1.

[0010] Furthermore, the temperature of the mixed reaction is 50-100° C., and the time is 6-24 hours.

[0011] Furthermore, the mixed reaction is carried out by heating in two stages, wherein the temperature of the first stage reaction is 50-70° C. and the time is 2-6 hours, and the temperature of the second stage reaction is 70-100° C. and the time is 4-18 hours.

[0012] Furthermore, the hydrogen bond donor is selected from one or more of urea, thiourea, ethylene glycol or glycerol.

[0013] Furthermore, the tertiary amine compound has the following structural formula: ; Among them, R is selected from C1~C 16 One or two of alkyl, hydroxyethyl, hydroxypropyl or aromatic groups.

[0014] Furthermore, the α,ω-dihalogenated alkane has the following structural formula: ; Wherein, X1 and X2 are one or two of chlorine, bromine, fluorine or iodine, and n is an integer ≥2.

[0015] Furthermore, the molar ratio of the hydrogen bond donor, the tertiary amine compound and the α,ω-dihalogenated alkane is 1-4:2-2.5:1.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The functionalized ionic liquid clay stabilizer of the present invention is composed of a low molecular weight diquaternary ammonium salt and a hydrogen bond donor. It does not cause secondary damage to the reservoir and can be used in low-permeability and ultra-low-permeability reservoirs. In addition, the functionalized ionic liquid clay stabilizer of the present invention has a high charge density, significant anti-swelling effect, strong water washability, good long-term performance, and strong temperature resistance, and can be used in high-temperature and ultra-high-temperature reservoirs. At the same time, the functionalized ionic liquid clay stabilizer of the present invention has little effect on the performance of the fracturing fluid and does not affect the sand-carrying capacity of the fracturing fluid, and can be used in hydraulic fracturing.

[0017] (2) The functionalized ionic liquid clay stabilizer of the present invention is prepared by reacting a tertiary amine compound with an α,ω-dihalogenated alkane to form a diquaternary ammonium salt, which is then reacted with a hydrogen bond donor to form an ionic liquid. The ionic liquid can serve as a solvent for the diquaternary ammonium salt formation reaction, thereby promoting the quaternization reaction and increasing the yield of the ionic liquid. The preparation method of the present invention is simple, the reaction process is safe and controllable, and it is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The chemical reaction formula for preparing the functionalized ionic liquid clay stabilizer in one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0019] It should be noted that, in the case of no conflict, the embodiments in this application and the features in the embodiments can be combined with each other. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope. The present invention will be described in detail below in conjunction with the embodiments.

[0020] In order to achieve the above object, an embodiment of the present invention provides a functionalized ionic liquid clay stabilizer, which is prepared from a diquaternary ammonium salt of Formula 1 and a hydrogen bond donor, wherein the structural formula of the diquaternary ammonium salt is: Formula 1; Among them, R is selected from C1~C 16wherein X1 and X2 are selected from one or both of chlorine, bromine, fluorine, and iodine; and n is an integer ≥ 2. Furthermore, n is preferably an integer from 2 to 6.

[0021] In order to further improve the anti-swelling effect of the functionalized ionic liquid clay stabilizer and reduce the raw material cost, in some preferred embodiments of the present invention, the hydrogen bond donor is selected from one or more of urea, thiourea, ethylene glycol or glycerol.

[0022] Another aspect of the present invention provides a method for preparing the aforementioned functionalized ionic liquid clay stabilizer, comprising the following steps: mixing a tertiary amine compound, an α,ω-dihalogenated alkane, and a hydrogen bond donor, wherein the tertiary amine compound and the α,ω-dihalogenated alkane react to produce a diquaternary ammonium salt of Formula 1, and the diquaternary ammonium salt reacts with the hydrogen bond donor to obtain the functionalized ionic liquid clay stabilizer; Wherein, the structural formula of described diquaternary ammonium salt is: Formula 1.

[0023] In a preferred embodiment of the present invention, the tertiary amine compound has the following structural formula: ; wherein R is selected from C1~C 16 One or two of an alkyl group, a hydroxyethyl group, a hydroxypropyl group or an aromatic group; further, the aromatic group is preferably a phenyl group, a benzyl group or a phenethyl group.

[0024] In a preferred embodiment of the present invention, the α,ω-dihalogenated alkane has the following structural formula: ; wherein X1 and X2 are selected from one or two of chlorine, bromine, fluorine or iodine, preferably chlorine or bromine, and n is an integer ≥2, preferably a positive integer of 2 to 6, and more preferably 3 or 4.

[0025] In a preferred embodiment of the present invention, the molar ratio of the hydrogen bond donor, the tertiary amine compound and the α,ω-dihalogenated alkane is 1~4:2~2.5:1. The present invention synergistically controls the ratio of the above three components so that the functionalized ionic liquid clay stabilizer generated by the reaction has a suitable ionic liquid viscosity and charge density, greatly improving its anti-swelling effect, water washing resistance and temperature resistance. If the ratio of the hydrogen bond donor of the present invention is too high, it is easy to cause the cation concentration of the synthesized ionic liquid to be too low, resulting in a decrease in the performance of the clay stabilizer. If the ratio of the hydrogen bond donor is too small, it also causes the performance of the clay stabilizer to be reduced. This is because the reaction is incomplete due to the small ratio of the hydrogen bond donor, and the hydrogen bond donor does not react completely with the diquaternary ammonium salt of Formula 1, making it difficult to form a uniform ionic liquid clay stabilizer. Most of the solid matter is diquaternary ammonium salt, and the solid-liquid formed is difficult to achieve good on-site application.

[0026] In a preferred embodiment of the present invention, the temperature of the mixed reaction is 50-100° C., and the time is 6-24 hours. Further preferably, the mixed reaction adopts two-stage heating to react, the temperature of the first stage reaction is 50-70° C., the time is 2-6 hours, and the temperature of the second stage reaction is 70-100° C., and the time is 4-18 hours. The present invention adopts a two-stage reaction, and first adopts a lower temperature to react to prevent the hydrogen bond donor from volatilizing. After the reaction is carried out for a period of time, the diquaternary ammonium salt generated combines with the hydrogen bond donor to generate a functionalized ionic liquid clay stabilizer, and the temperature resistance of the reaction system is enhanced, thereby increasing the temperature of the second stage reaction and improving the reaction rate.

[0027] In an exemplary embodiment of the present invention, taking urea as an example, the hydrogen bond donor is Figure 1 The chemical reaction process for preparing functionalized ionic liquid clay stabilizer is as follows: .

[0028] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0029] Example 1 The preparation method of the functionalized ionic liquid clay stabilizer of this embodiment comprises the following steps: 0.2 mol of urea, 0.1 mol of dimethylethanolamine and 0.05 mol of 1,4-dichlorobutane were mixed and stirred to uniformly disperse the urea. The temperature was raised to 50° C. and reacted for 6 h, and then continued to rise to 90° C. and reacted for 12 h to obtain a functionalized ionic liquid clay stabilizer.

[0030] Example 2 The preparation method of the functionalized ionic liquid clay stabilizer of this embodiment comprises the following steps: 0.1 mol of thiourea, 0.1 mol of ethylene glycol, 0.1 mol of dimethylethanolamine and 0.05 mol of 1,4-dichlorobutane were mixed and stirred until the thiourea was evenly dispersed. The mixture was heated to 50° C. and reacted for 6 h and then at 90° C. for 12 h to obtain a functionalized ionic liquid clay stabilizer.

[0031] Example 3 The preparation method of the functionalized ionic liquid clay stabilizer of this embodiment comprises the following steps: 0.1 mol of ethylene glycol, 0.1 mol of dimethylethanolamine and 0.05 mol of 1,3-dichloropropane were mixed evenly, heated to 50° C. for reaction for 4 h, and then at 90° C. for reaction for 8 h to obtain a functionalized ionic liquid clay stabilizer.

[0032] Example 4 The preparation method of the functionalized ionic liquid clay stabilizer of this embodiment comprises the following steps: 0.1 mol of ethylene glycol, 0.1 mol of dimethylbenzylamine and 0.05 mol of 1,3-dichloropropane were mixed evenly, heated to 50° C. for reaction for 4 h, and then at 90° C. for reaction for 8 h to obtain a functionalized ionic liquid clay stabilizer.

[0033] Example 5 The preparation method of the functionalized ionic liquid clay stabilizer of this embodiment comprises the following steps: 0.1 mol of ethylene glycol, 0.05 mol of glycerol, 0.09 mol of dimethylethanolamine, 0.01 mol of dodecylamine and 0.05 mol of 1,3-dichloropropane were mixed evenly, heated to 50° C. for reaction for 4 h and then at 90° C. for reaction for 8 h to obtain a functionalized ionic liquid clay stabilizer.

[0034] Comparative Example 1 0.25 mol of urea, 0.1 mol of dimethylethanolamine and 0.05 mol of 1,4-dichlorobutane were mixed and stirred to uniformly disperse the urea. The temperature was raised to 50° C. and reacted for 6 h, and then continued to rise to 90° C. and reacted for 12 h to obtain a functionalized ionic liquid clay stabilizer.

[0035] Comparative Example 2 0.25 mol of ethylene glycol, 0.1 mol of dimethylethanolamine and 0.05 mol of 1,3-dichloropropane were mixed evenly, heated to 50° C. for reaction for 4 h, and then at 90° C. for reaction for 8 h to obtain a functionalized ionic liquid clay stabilizer.

[0036] Performance Testing Test Example 1: Evaluation of the anti-swelling rate of clay stabilizer: Take 0.7g of clay stabilizer and add 100g of distilled water and shake well to obtain a clay stabilizer solution. Weigh 0.50g of sodium bentonite and place it into a 10mL centrifuge tube. Add 10mL of clay stabilizer solution and shake well. Let it stand at room temperature for 2 hours. Place it in a centrifuge and centrifuge at 1500r / min for 15 minutes. Read the volume V1 of the expanded sodium bentonite.

[0037] The volume of sodium bentonite after expansion is V2 after replacing the clay stabilizer solution with distilled water.

[0038] The volume of sodium bentonite after expansion is V0 when kerosene is used to replace the clay stabilizer solution.

[0039] Calculation method of anti-swelling rate:

[0040] The anti-swelling rate test results of the clay stabilizer of the present invention are shown in Table 1.

[0041] Test Example 2: Evaluation of the water washability of clay stabilizers: Discard the supernatant in the centrifuge tube after centrifugation in Test Example 1, add 10 mL of distilled water, shake thoroughly, let stand for 2 hours, put into a centrifuge, and centrifuge at a speed of 1500 r / min for 15 minutes. Repeat the above operation twice, read the volume of the sodium bentonite after expansion, and calculate the anti-swelling rate in the same way as in Test Example 1.

[0042] The test results of the water washability of the clay stabilizer of the present invention are shown in Table 1.

[0043] Test Example 3: Evaluation of Jelly Viscosity Retention of Clay Stabilizer: 1000 mL of 0.4% hydroxypropyl guar gum fracturing fluid base fluid was prepared and divided into two equal parts, one of which was a blank sample and the other was added with 0.7% by mass of clay stabilizer.

[0044] The fracturing fluid cross-linking fluid formula is prepared with a mass fraction of 3.0% sodium tetraborate and a mass fraction of 10.0% sodium hydroxide.

[0045] Two parts of fracturing fluid base fluid are prepared into fracturing fluid gel according to the cross-linking ratio required by the test or a cross-linking ratio of 100:1, and then the apparent viscosity of the two gel samples at 90°C is measured respectively.

[0046] Calculation method of jelly viscosity retention rate:

[0047] y1——viscosity retention rate, expressed as a percentage; η2——apparent viscosity of the added clay stabilizer, mPa·s; η1——apparent viscosity of blank sample, mPa·s.

[0048] The test results of the jelly viscosity retention rate of the clay stabilizer of the present invention are shown in Table 1.

[0049] The clay stabilizer solution was placed in a sealed container for high temperature and high pressure heat treatment and heat treated at 300°C for 2 hours. The above operation was repeated to test the temperature resistance of the clay stabilizer. The test results are shown in Table 1.

[0050] Table 1

[0051] Test results show that the clay stabilizer prepared in the Examples of the present invention exhibits an anti-swelling rate ≥85%, a water-washing anti-swelling rate ≥80%, and a jelly viscosity retention rate ≥90%. Its temperature resistance reaches 300°C, demonstrating excellent performance and suitability for fracturing and reconstruction of high-temperature, ultra-high-temperature, low-permeability, and ultra-low-permeability reservoirs. However, the clay stabilizer prepared in the Comparative Example exhibits significantly lower anti-swelling and water-washing anti-swelling rates. This is due to the excessive use of hydrogen bond donors in the preparation of the clay stabilizer in the Comparative Example compared to the preparation of the Examples, which reduces the effective cation concentration and, in turn, impairs the anti-swelling effect of the clay stabilizer.

[0052] The embodiments described above are merely illustrative of embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. The present invention may also be implemented in other specific ways or in other specific forms without departing from the gist or essential features of the present invention. Therefore, the embodiments described should be considered in all respects as illustrative and not restrictive. The scope of the present invention should be described by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A functionalized ionic liquid clay stabilizer, characterized in that: It is prepared from a diquaternary ammonium salt of formula 1 and a hydrogen bond donor, and the structural formula of the diquaternary ammonium salt is: Formula 1; Among them, R is selected from C1~C 16 One or two of alkyl, hydroxyethyl, hydroxypropyl or aromatic groups; X1 and X2 are one or two of chlorine, bromine, fluorine or iodine; n is an integer ≥ 2; the hydrogen bond donor is selected from one or more of urea, thiourea, ethylene glycol or glycerol.

2. The functionalized ionic liquid clay stabilizer according to claim 1, characterized in that The n is an integer of 2 to 6.

3. A method for preparing a functionalized ionic liquid clay stabilizer according to claim 1 or 2, characterized in that: The following steps are involved: A tertiary amine compound, an α,ω-dihalogenated alkane, and a hydrogen bond donor are mixed and reacted, wherein the tertiary amine compound and the α,ω-dihalogenated alkane react to generate a diquaternary ammonium salt of Formula 1, and the diquaternary ammonium salt reacts with the hydrogen bond donor to obtain the functionalized ionic liquid clay stabilizer; Wherein, the structural formula of described diquaternary ammonium salt is: Formula 1.

4. The method for preparing the functionalized ionic liquid clay stabilizer according to claim 3, wherein: The temperature of the mixed reaction is 50-100° C., and the time is 6-24 hours.

5. The method for preparing the functionalized ionic liquid clay stabilizer according to claim 3, wherein: The mixed reaction is carried out by heating in two stages. The temperature of the first stage is 50-70° C. and the reaction time is 2-6 hours. The temperature of the second stage is 70-100° C. and the reaction time is 4-18 hours.

6. The method for preparing the functionalized ionic liquid clay stabilizer according to claim 3, characterized in that: The hydrogen bond donor is selected from one or more of urea, thiourea, ethylene glycol or glycerol.

7. The method for preparing the functionalized ionic liquid clay stabilizer according to claim 3, characterized in that: The tertiary amine compound has the following structural formula: ； Among them, R is selected from C1~C 16 One or two of alkyl, hydroxyethyl, hydroxypropyl or aromatic groups.

8. The method for preparing a functionalized ionic liquid clay stabilizer according to claim 3, wherein: The α,ω-dihalogenated alkane has the following structural formula: ； Wherein, X1 and X2 are selected from one or two of chlorine, bromine, fluorine or iodine, and n is an integer ≥2.

9. The method for preparing the functionalized ionic liquid clay stabilizer according to claim 3, wherein: The molar ratio of the hydrogen bond donor, the tertiary amine compound and the α,ω-dihalogenated alkane is 1-4:2-2.5:1.

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