Compound retarder based on deep eutectic solvent as well as preparation method and application of compound retarder

Abstract

The invention discloses a compound retarder based on a deep eutectic solvent as well as a preparation method and application of the compound retarder. The preparation method comprises the following steps: heating choline chloride and ethylene glycol to prepare a deep eutectic solvent; and mixing the deep eutectic solvent, hexadecyl trimethyl ammonium chloride and water to obtain the compound retarder. The invention also discloses a retarding acid solution prepared from the compound retarder. The compound retarder provided by the invention has an efficient retarding effect, and the deep eutectic solvent prepared from choline chloride and ethylene glycol forms a low-melting-point mixture by virtue of a hydrogen bond donor and a hydrogen bond acceptor under the eutectic action. The deep eutectic solvent can generate hydrogen-bond interaction with H < + > in acid liquor or active sites on the surface of rock, so that the reaction activity of acid rock is reduced. According to the compound retarder provided by the invention, the retarding performance is optimized through a synergistic effect, and the cost and environmental harm of the retarder are remarkably reduced while an efficient retarding effect is maintained.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction technology, and particularly relates to a compound retarder based on deep eutectic solvent, its preparation method and application. Background Technology

[0002] In acidizing enhancement processes for oil extraction, retarders are key additives for controlling the reaction rate between acid and formation rocks. Taking carbonate formations as an example, excessively rapid reaction between acid (such as hydrochloric acid or argonic acid) and rock can easily lead to wellbore structural damage, decreased permeability, and even wellbore collapse. Current technologies utilize retarders to slow down the acid-rock reaction, extending the effective reach of the acid within the formation and improving acidizing efficiency.

[0003] Existing retarder technologies have significant limitations. For example, traditional chemical retarder acids contain heavy metal salts (such as chromium and copper salts), which delay the reaction through ion complexation. However, heavy metals are highly toxic and bioaccumulative, easily polluting groundwater and soil, and their long-term residues affect subsequent mining. Polymer retarders, such as polyacrylamide, reduce the acid diffusion rate through molecular chain entanglement or adsorption. Although they have excellent retarding effects, their synthesis requires high temperature and pressure conditions, resulting in high raw material costs. In addition, the stable structure of polymers makes them difficult to biodegrade and easily clogs formation pores. Emulsified retarders isolate the acid from the rock through an oil-water emulsion system, but the residual oil phase after demulsification can easily clog seepage channels, and additional demulsifiers are required, increasing operating costs and environmental risks. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a compound retarder based on a deep eutectic solvent, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On one hand, the present invention provides a method for preparing a compound retarder based on a deep eutectic solvent, comprising the following steps:

[0007] A deep eutectic solvent was prepared by heating choline chloride with ethylene glycol.

[0008] The compound retarder is obtained by mixing the deep eutectic solvent, hexadecyltrimethylammonium chloride, and water.

[0009] In a preferred embodiment, the molar ratio of choline chloride to ethylene glycol is 1:(1-2).

[0010] And / or, the heating temperature is 90-100°C, and the time is 2-3 hours.

[0011] In some specific embodiments, the step of mixing the deep eutectic solvent, hexadecyltrimethylammonium chloride, and water is as follows:

[0012] An aqueous solution of a deep eutectic solvent is mixed with an aqueous solution of hexadecyltrimethylammonium chloride.

[0013] In a preferred embodiment, the aqueous solution of hexadecyltrimethylammonium chloride has a mass fraction of 3% to 5%.

[0014] And / or, the mass fraction of the aqueous solution of the deep eutectic solvent is 0.1% to 5%.

[0015] And / or, the volume ratio of the aqueous solution of the deep eutectic solvent to the aqueous solution of hexadecyltrimethylammonium chloride is (1-2):1.

[0016] On the other hand, the present invention provides a compound retarder obtained by the above preparation method.

[0017] In another aspect, the present invention provides the application of the above-mentioned compound retarder in oil extraction.

[0018] Preferably, its application in the preparation of slow-release acid solutions.

[0019] In another aspect, the present invention provides a slow-release acid solution prepared from the above-mentioned compound slow-release agent.

[0020] Preferably, the raw materials for preparing the slow-release acid solution include the compound slow-release agent and hydrochloric acid.

[0021] In some specific embodiments, the raw materials for preparing the slow-release acid solution include a compound slow-release agent and hydrochloric acid.

[0022] In another aspect, the present invention provides a method for preparing the above-mentioned slow-release acid solution, wherein the preparation method comprises mixing a compound slow-release agent and hydrochloric acid with a mass concentration of 10% to 20% at a volume ratio of 2:(96 to 100).

[0023] The compound retarder provided by this invention has a highly efficient retarding effect. The deep eutectic solvent (DES) formulated from choline chloride and ethylene glycol is a low-melting-point mixture formed by hydrogen bond donors and acceptors through a low-melting-point reaction. It possesses characteristics such as low toxicity, biodegradability, high solubility, and low cost. This deep eutectic solvent can react with H+ in acidic solutions. + Hydrogen bonding may occur at active sites on the rock surface, reducing the reactivity of acidic rocks. The compound retarder provided by this invention optimizes retarding performance through synergistic effects, significantly reducing retarder costs and environmental hazards while maintaining high-efficiency retarding.

[0024] Beneficial effects of this invention:

[0025] (1) The compound retarder provided by the present invention can further reduce the acid rock reaction rate, improve the acidizing effect, and reduce the risk of well wall collapse caused by excessive acid etching.

[0026] (2) The compound retarder provided by this invention has a wide range of sources and is inexpensive, resulting in low production costs. At the same time, the low melting point of the deep eutectic solvent simplifies the preparation process, further reducing production and application costs.

[0027] (3) The compound retarder provided by the present invention significantly reduces the content of toxic components. After use, the residual substances can be rapidly decomposed in the natural environment, which meets the industry development needs of green oil extraction.

[0028] (4) In the compound retarder provided by the present invention, the deep eutectic solvent has high solubility and stable chemical structure, which can enhance the tolerance of the retarder in high temperature and high salinity strata environment, and make the retarding performance stable for a long time under complex geological conditions.

[0029] (5) The compound retarder provided by the present invention is compatible with common acidification liquid systems such as hydrochloric acid and argillaceous acid, and is applicable to carbonate rock formations of different properties, and has universality. Attached Figure Description

[0030] Figure 1 This is a graph showing the retardation performance evaluation of different DES in Embodiment 1 of the present invention;

[0031] Figure 2 This is a photograph of the acid-rock reaction experiment in Example 1 of the present invention;

[0032] Figure 3 This is a graph showing the retarding performance evaluation of the compound retarder in Example 2 of the present invention;

[0033] Figure 4 This is a cross-sectional view of calcium carbonate after the acid-rock reaction experiment in Example 2 of the present invention. Detailed Implementation

[0034] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0035] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0036] Example 1

[0037] (1) Add a certain amount of choline chloride and ethylene glycol to a beaker at a molar ratio of 1:2, place it in a heat-collecting constant temperature (magnetic stirrer) water bath, turn on the magnetic stirrer, adjust the temperature to 95℃ and react for 2 hours to obtain the deep eutectic solvent DES; after mixing the deep eutectic solvent DES with different volumes of water, a deep eutectic solvent aqueous solution with a DES mass concentration of 0.1% to 5% is obtained;

[0038] (2) Weigh 25g of calcium carbonate powder using an electronic scale, pour it into the container below the YLJ600 press, close the valve, adjust the pressure to 15MPa, wait for 6 minutes, and remove the cylindrical calcium carbonate block with a diameter of 25mm; wrap it with polyurethane glue to simulate carbonate rock, leaving only one end face for the acid-rock reaction, with an end face area of ​​approximately 4.9cm². 2 ;

[0039] (3) Prepare the following acid solution system:

[0040] ① 2 mL of DES aqueous solution (DES mass concentration of 0.1%) and 98 mL of hydrochloric acid with a mass concentration of 10%;

[0041] ② 2 mL of DES aqueous solution (DES mass concentration of 1.0%) and 98 mL of hydrochloric acid with a mass concentration of 10%;

[0042] ③ 2 mL of DES aqueous solution (DES mass concentration of 2%) and 98 mL of hydrochloric acid with a mass concentration of 10%;

[0043] ④ 2 mL of DES aqueous solution (DES mass concentration of 3%) and 98 mL of hydrochloric acid with a mass concentration of 10%;

[0044] ⑤ 2 mL of DES aqueous solution (DES mass concentration of 4%) and 98 mL of hydrochloric acid with a mass concentration of 10%;

[0045] ⑥ 2 mL of DES aqueous solution (DES mass concentration of 5%) and 98 mL of hydrochloric acid mass concentration of 10%;

[0046] ⑦ 100 mL of 10% hydrochloric acid (blank control);

[0047] Carbonate rock cores were reacted with different acid systems at room temperature (15℃) for 12 minutes. After recording the data, the acid-rock reaction rate was calculated using the weight loss method, as shown in the following formula:

[0048]

[0049] In the formula: v is the static acid-rock reaction rate, g / (m 2 ·s); m0 is the core mass before reaction, in g; mi A is the mass of the core after the reaction, in g; A is the surface area of ​​the core reaction surface, in m. 2 720 is a fixed reaction time of 720s.

[0050] The acid-rock reaction rate results measured for the different acid systems are shown in the figure above. Figure 1 See Table 1 for physical images of the acid-rock reaction experiment. Figure 2 .

[0051] Table 1

[0052]

[0053] In Table 1, the slow rate = (9.42 – average reaction rate of acid-rock) / 9.42 * 100%.

[0054] From Table 1 and Figure 1 It can be seen that the deep eutectic solvent DES in this invention has a certain retardation effect, and within a certain range, its retardation effect is enhanced with the increase of concentration.

[0055] Example 2

[0056] (1) Add a certain amount of choline chloride and ethylene glycol to a beaker at a molar ratio of 1:2, place it in a heat-collecting constant temperature (magnetic stirrer) water bath, turn on the magnetic stirrer, adjust the temperature to 95℃ and react for 2 hours to obtain deep eutectic solvent DES;; after mixing the deep eutectic solvent DES with water, a deep eutectic solvent aqueous solution with a DES mass concentration of 3% is obtained.

[0057] (2) Weigh 25g of calcium carbonate powder using an electronic scale, pour it into the container below the YLJ600 press, close the valve, adjust the pressure to 15MPa, wait for 6 minutes, and remove the cylindrical calcium carbonate block with a diameter of 25mm; wrap it with polyurethane glue to simulate carbonate rock, leaving only one end face for the acid-rock reaction, with an end face area of ​​approximately 4.9cm². 2 ;

[0058] (3) Prepare the following acid solution system:

[0059] ① A 2 mL volume of 3% DES aqueous solution and a 98 mL volume of 10% hydrochloric acid;

[0060] ② A 2 mL volume of 3% hexadecyltrimethylammonium chloride aqueous solution and a 98 mL volume of 10% hydrochloric acid;

[0061] ③ 1 mL of 3% DES aqueous solution, 1 mL of 3% hexadecyltrimethylammonium chloride aqueous solution, and 98 mL of 10% hydrochloric acid;

[0062] Carbonate rock cores were reacted with different acid systems at room temperature (15°C) for 12 minutes. After recording the data, the acid-rock reaction rate was calculated using the weight loss method according to the formula in Example 1. The test results are shown in [Figure 1].

[0063] Table 2 and Figure 3 , Figure 4 The image shown is a cross-sectional view of calcium carbonate after the acid-rock reaction experiment.

[0064]

[0065] Table 2

[0066]

[0067]

[0068] As shown in Table 2, the retarder based on deep eutectic solvent has excellent retarding performance at the same concentration, which is slightly lower than that of conventional retarder.

[0069] In this embodiment, a retarder acid solution system was prepared using 10% hydrochloric acid, DES, and hexadecyltrimethylammonium chloride. After being placed at room temperature for 24 hours, no flocculation or precipitation occurred, indicating good compatibility of the system. After being placed at 90°C for 8 hours, no stratification or precipitation occurred, indicating good thermal stability of the system.

[0070] The compound retarder of this invention utilizes readily available and low-cost raw materials. The preparation process of DES is simple; based on its low melting point, it can be produced in a one-pot process at room temperature (around 25°C) without the need for special equipment or high-temperature, high-pressure conditions. Compared to the high-temperature polymerization processes required for traditional polymer retarders, this invention significantly reduces energy consumption and lowers equipment investment and maintenance costs. Furthermore, the compound retarder provided by this invention eliminates the need for demulsifiers, as is required with emulsifying retarders, further reducing usage costs.

[0071] Furthermore, DES is a molten salt, where interactions occur through hydrogen bonds formed by the salt's anions or metal halide bonds; ionic liquids (ILS), on the other hand, rely on electrostatic forces between their anions and cations. Therefore, DES is a special type of ILS, typically a viscous liquid at room temperature, primarily composed of crystalline solids. DES is soluble in water and biodegradable. With negligible vapor pressure, it is non-flammable, non-explosive, non-toxic, and exhibits good electrochemical and thermal stability, earning it the title of a "green solvent."

[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a compound retarder based on a deep eutectic solvent, characterized in that, Includes the following steps: A deep eutectic solvent was prepared by heating choline chloride with ethylene glycol. The compound retarder is obtained by mixing the deep eutectic solvent, hexadecyltrimethylammonium chloride, and water.

2. The preparation method according to claim 1, characterized in that, The molar ratio of choline chloride to ethylene glycol is 1:(1-2); And / or, the heating temperature is 90-100°C, and the time is 2-3 hours.

3. The preparation method according to claim 1, characterized in that, The step of mixing the deep eutectic solvent, hexadecyltrimethylammonium chloride, and water is as follows: An aqueous solution of a deep eutectic solvent is mixed with an aqueous solution of hexadecyltrimethylammonium chloride.

4. The preparation method according to claim 1, characterized in that, The aqueous solution of the hexadecyltrimethylammonium chloride has a mass fraction of 3% to 5%. And / or, the mass fraction of the aqueous solution of the deep eutectic solvent is 0.1% to 5%; And / or, the volume ratio of the aqueous solution of the deep eutectic solvent to the aqueous solution of hexadecyltrimethylammonium chloride is (1-2):

1.

5. The compound retarder obtained by any of the preparation methods described in claims 1-4.

6. The application of the compound retarder according to claim 5 in oil extraction.

7. The use according to claim 6, characterized in that, Application in the preparation of slow-release acid solutions.

8. A slow-release acid solution prepared from the compound slow-release agent as described in claim 5.

9. The slow-release acid solution according to claim 8, characterized in that, The raw materials for preparing the slow-release acid solution include the compound slow-release agent and hydrochloric acid.

10. The method for preparing the slow-release acid solution according to claim 8, characterized in that, The preparation method is as follows: the compound retarder and hydrochloric acid with a mass concentration of 10% to 20% are mixed at a volume ratio of 2:(96 to 100).

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