Zinc chloride solution for demulsification of water-in-oil emulsion

Abstract

A method of demulsifying a water-in-crude oil emulsion includes mixing an aqueous solution including water and 0.5 to 1 percent by weight (wt. %) zinc chloride with the water-in-crude oil emulsion to obtain an emulsion mixture. The water-in-crude oil emulsion includes 28 to 32% water by volume and 68 to 72% Arabian crude oil by volume. The Arabian crude oil includes 30-40 wt. % aromatics, 35-40 wt. % saturates, 10-20 wt. % asphaltenes, and 10-20 wt. % resins based on the total weight of the Arabian crude oil. The method includes heating the emulsion mixture to a temperature of 65 to 75° C. for 12 to 24 hours. The method further includes sonicating the heated emulsion mixture for 20 to 140 minutes and separating the sonicated heated emulsion to form an oil phase and a water phase.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 706,282, filed Oct. 11, 2024, which is incorporated herein by reference in its entirety.BACKGROUNDTechnical Field

[0002] The present disclosure is directed to a demulsification method, and more particularly towards a demulsification method for water-in-oil emulsions using a zinc chloride (ZnCl2) aqueous solution.Description of Related Art

[0003] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

[0004] Emulsions, particularly oil / water emulsions, are commonly encountered in various industrial processes such as oil extraction, petrochemical refining, and wastewater treatment. Separation of oil and water phases in the emulsions is needed for efficient processing and oil recovery; however, the separation process is often challenging due to the stability of the emulsion, resulting in prolonged separation times and reduced efficiency. Numerous methods and compositions have been developed to enhance demulsification performances of oil / water emulsions. Common methods may include use of chemical demulsifiers. Demulsifiers work by destabilizing an emulsion and promoting coalescence of oil droplets for easier separation; however, demulsification processes can be challenging, particularly when dealing with stable or complex emulsions. Calcium chloride has been used as a demulsifier for emulsions prepared using emulsifying oil EMULGOL ES-12, but not for crude oil emulsions [Pacholski, P. et al., Expert analysis of the chemical demulsification of oil-in-water emulsions by inorganic salts, Sep. Sci. Technol., 2020, 55, 2421-2432]. Demulsification of crude oil emulsions has been seen to be enhanced when sea water was used instead of DI water [Adewunmi, A. A. and Kamal, M. S. Demulsification of water-in-oil emulsions using ionic liquids: Effects of counterion and water type, J. Mol. Liq., 2019, 279, 411-419]. Demulsification may be conducted at temperatures ranging between 60-80° C., and calcium chloride (CaCl2)) was used for treating heavy oil wastewater, where the sample was treated with heat prior to the dehydration step with calcium chloride [Tong, K. et al., Evaluation of calcium chloride for synergistic demulsification of super heavy oil wastewater, Colloids Surfaces A Physicochem. Eng. Asp., 2013, 419, 46-52].

[0005] A disadvantage of using CaCl2) for demulsification is its reduced efficiency at ambient temperatures, often using elevated temperatures (60-80° C.) to achieve effective separation. Elevated temperatures increase energy consumption and operational costs of the process. Additionally, the demulsification performance of CaCl2) may vary depending on the emulsion type and composition. Further, its mechanism is not well understood for crude oil emulsions, particularly in the absence of synergistic factors like heat and / or co-solutes like ZnCl2 and / or components in seawater.

[0006] Current methods suffer from one or more drawbacks hindering their adoption. Accordingly, an object of the present disclosure to provide an emulsion system that may circumvent drawbacks, such as reduced efficiency at ambient temperatures, energy consumption, operational costs, and the like, known in the art.SUMMARY

[0007] In an exemplary embodiment, a method of demulsifying a water-in-crude oil emulsion is described. The method includes mixing an aqueous solution including water and 0.5 to 1 percent by weight (wt. %) zinc chloride with the water-in-crude oil emulsion to obtain an emulsion mixture. The percent by weight is based on a total weight of the aqueous solution. The water-in-crude oil emulsion includes 28 to 32% water by volume and 68 to 72% Arabian crude oil by volume. The Arabian crude oil includes 30-40 wt. % aromatics, 35-40 wt. % saturates, 10-20 wt. % asphaltenes, and 10-20 wt. % resins based on the total weight of the Arabian crude oil. The method includes heating the emulsion mixture to a temperature of 65 to 75° C. for 12 to 24 hours. The method includes sonicating the heated emulsion mixture for 20 to 140 minutes and separating the sonicated heated emulsion to form an oil phase and a water phase.

[0008] In some embodiments, the zinc chloride is present in the aqueous solution in an amount of 0.6 to 0.8 wt. %, and the separating is carried out in a vertical separator column in sonic communication with a mixing tank in which the sonicating is carried out. The vertical separator column has a heated emulsion inlet at a height no lower than ½ a height of the vertical separator column measured from a bottom outlet to a top outlet.

[0009] In some embodiments, the zinc chloride is present in the aqueous solution in an amount of 0.74 to 0.76 wt. %.

[0010] In some embodiments, the mixing occurs for 10 to 30 minutes.

[0011] In some embodiments, the mixing occurs for 15 to 25 minutes.

[0012] In some embodiments, the heating occurs at a temperature of 68 to 72° C.

[0013] In some embodiments, the heating occurs at a temperature of 70° C.

[0014] In some embodiments, the heating occurs for 22 hours, the sonicating occurs for 2 hours, and a dehydration efficiency of the demulsification mixture is from 85 to 95% based on a volume of water.

[0015] In some embodiments, the heating occurs for 14 hours, the sonicating occurs for 30 minutes, and a dehydration efficiency of the demulsification mixture is from 35 to 45% based on a volume of water.

[0016] In some embodiments, the water-in-crude oil emulsion includes 30% water by volume and 70% Arabian crude oil by volume.

[0017] In some embodiments, a density of the Arabian crude oil is 0.88 to 0.89 kilograms per cubic meter (kg / m3).

[0018] In some embodiments, an API gravity of the Arabian crude oil is 28 to 28.5.

[0019] In some embodiments, a viscosity of the Arabian crude oil is 14 to 16 megapascals per second (mPa / s).

[0020] In some embodiments, the mixing occurs at a speed of 600 to 800 revolutions per minute (rpm).

[0021] In some embodiments, the crude oil is an external phase.

[0022] In some embodiments, the Arabian crude oil includes 31-35 wt. % aromatics, 38-39 wt. % saturates, 11-13 wt. % asphaltenes, and 15-18 wt. % resins based on the total weight of the Arabian crude oil.

[0023] In some embodiments, the sonicating occurs for 20 to 40 minutes.

[0024] In some embodiments, the sonicating occurs for 110 to 130 minutes.

[0025] In some embodiments, the heating occurs for 20 to 24 hours.

[0026] In some embodiments, the heating occurs for 12 to 16 hours.

[0027] The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] A more complete appreciation of this disclosure and many of the attendant advantages thereof may be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

[0029] FIG. 1 is a schematic flowchart of a method of demulsifying a water-in-crude oil emulsion, according to certain embodiments.

[0030] FIG. 2A depicts emulsion dehydration at 30% water cut and no ZnCl2 heated at 70° C. for 22 hours and sonicated for 2 hours, according to certain embodiments.

[0031] FIG. 2B depicts emulsion dehydration at 30% water cut with 0.75 wt. % ZnCl2 heated at 70° C. for 14 hours and sonicated for 30 hours, according to certain embodiments.

[0032] FIG. 2C depicts emulsion dehydration at 30% water cut with 0.75 wt. % ZnCl2 heated at 70° C. for 22 hours and sonicated for 2 hours, according to certain embodiments.DETAILED DESCRIPTION

[0033] In the drawings, like numbered reference numerals will be used to designate identical or corresponding parts throughout the several views. Further, as used herein, the words “a,”“an,” and the like generally carry a meaning of “one or more,” unless stated otherwise.

[0034] Furthermore, the terms “approximately,”“approximate,”“about,” and similar terms generally refer to ranges that include the identified value within a margin of 20%, 10%, or preferably 5%, and any values therebetween.

[0035] Aspects of the present disclosure are directed to an environmentally conscious method for demulsification of crude oil / water emulsions, utilizing zinc chloride (ZnCl2) as a chemical demulsifier in conjunction with ultrasonic treatment. The method involves addition of ZnCl2 at a concentration of 0.75 percent by weight (wt. %) relative to the emulsion, followed by sonication at a high temperature of 70° C. for 2 hours. The combined treatment destabilizes the stable emulsion, achieving effective phase separation within 22 hours. The approach not only enhances separation efficiency but also minimizes reliance on hazardous organic solvents typically used in demulsification. This method holds promise for applications in petroleum processing, chemical manufacturing, and wastewater treatment industries, where rapid and efficient oil / water separation is used.

[0036] A method of demulsifying a water-in-crude oil emulsion is described (FIG. 1). In some embodiments, the crude oil may be light crude, medium crude, heavy crude, extra heavy crude, sweet crude, sour crude, a combination thereof, and the like. In some embodiments, the crude oil may be one or more of Brent crude, West Texas Intermediate (WTI), Dubai crude, Oman crude, Urals, Bonny light, Tapis, Murban, a combination thereof, and the like. Certain other examples of regional crude oils may include, but are not limited to, WTI, Laska North Slope, Western Canadian Select (WCS), Bakken blend, Maya, Venezuela Heavy Crude, Bonny Light, Forcados, Cabinda, Arab light, Arab heavy, Basrah light, Basrah heavy, Tapis, Daqing, Minas, combinations thereof, and the like. In a preferred embodiment, the crude oil is an Arabian crude oil. Although the description herein provided refers to the use of Arabian crude oil as a preferred crude oil, it may be understood by a person skilled in the art that the method of present disclosure may be adapted to other crude oils as well, albeit with a few variations, and such an adaptation is obvious to a person skilled in the art. A method 50 of demulsifying a water-in-crude oil emulsion is described in FIG. 1. The order in which the method 50 is described is not intended to be construed as a limitation, and any number of the described method steps can be combined in any order to implement the method 50. Additionally, individual steps may be removed or skipped from the method 50 without departing from the spirit and scope of the present disclosure.

[0037] At step 52, the method 50 includes mixing an aqueous solution consisting of water and 0.5 to 1 percent by weight (wt. %), preferably 0.55 to 0.95 wt. %, preferably 0.6 to 0.9 wt. %, preferably 0.65 to 0.85 wt. %, preferably 0.7 to 0.8 wt. %, preferably 0.71 to 0.79 wt. %, preferably 0.72 to 0.78 wt. %, preferably about 0.73 to 0.77 wt. %, more preferably 0.74 to 0.76 wt. %, and yet more preferably about 0.75 wt. % zinc chloride with the water-in-crude oil emulsion to obtain an emulsion mixture. Percent by weight is based on a total weight of the aqueous solution. In some embodiments, in the water-in-crude oil emulsion the crude oil is a continuous (i.e., external) phase and the water is a dispersed (i.e., internal) phase. In some embodiments, the crude oil is an external phase. In some embodiments, the method of the present disclosure may be adapted to an oil-in-water emulsion as well, albeit with a few variations, as may be obvious to a person skilled in the art. In some embodiments, the mixing may occur manually via a stirrer, a magnetic stir bar and stir plate, a centrifuge, a shaker, a combination thereof, and the like. In a preferred embodiment, the mixing occurs via a centrifuge.

[0038] In some embodiments, the zinc chloride is present in the aqueous solution in an amount of 0.6 to 0.8 wt. %, preferably 0.65 to 0.79 wt. %, preferably 0.7 to 0.78 wt. %, preferably 0.72 to 0.77 wt. %, preferably 0.73 to 0.76 wt. %, and more preferably 0.74 to 0.76 wt. %. In some embodiments, the zinc chloride is present in the aqueous solution in an amount of 0.74 to 0.76 wt. %, preferably 0.741 to 0.759 wt. %, preferably 0.742 to 0.758 wt. %, preferably 0.743 to 0.757 wt. %, preferably 0.744 to 0.756 wt. %, preferably 0.745 to 0.755 wt. %, preferably 0.746 to 0.754 wt. %, preferably 0.747 to 0.753 wt. %, preferably 0.748 to 0.752 wt. %, more preferably 0.749 to 0.751 wt. %, and yet more preferably about 0.75 wt. %.

[0039] In some embodiments, the zinc chloride is present in the aqueous solution in an amount of 10,000 to 50,000 ppm, preferably 15,000 to 45,000 ppm, preferably 20,000 to 40,000 ppm, more preferably 25,000 to 35,000 ppm, and yet more preferably about 30,000 ppm. In some embodiments, the ZnCl2 is acting as a demulsifying agent where it may disrupt electrostatic or steric stabilization of water droplets and may alter interfacial tension and / or destabilize asphaltene films

[0040] The aqueous solution includes water, and the water may be tap water, hard water, deionized water, distilled water, double distilled water, a combination thereof, and any other type of water known. In a preferred embodiment, the water is deionized water. In certain embodiments, the aqueous solution includes brine. In certain other embodiments, the aqueous solution includes a combination of water and brine.

[0041] In certain embodiments, a volumetric ratio (i.e., v / v ratio) of the aqueous solution to the crude oil in the water-in-crude oil emulsion is 1:10 to 10:1, preferably 1:9 to 9:1, preferably 1:8 to 8:1, preferably 1:7 to 7:1, preferably 1:6 to 6:1, preferably 1:5 to 5:1, preferably 1:4 to 4:1, preferably 1:3 to 3:1, and preferably 1:2 to 2:1. In a preferred embodiment, the v / v ratio of the aqueous solution to the crude oil in the water-in-crude oil emulsion is 1:2 to 1:3, preferably 1:2 to 1:2.5, and more preferably about 1:2.3.

[0042] The water-in-crude oil emulsion includes 28 to 32%, preferably 28.5 to 31.5%, preferably 29 to 31%, more preferably 29.5 to 30.5%, and yet more preferably about 30% water by volume and 68 to 72%, preferably 68.5 to 71.5%, preferably 69 to 71%, more preferably 69.5 to 70.5%, and yet more preferably about 70% Arabian crude oil by volume. In a specific embodiment, the water-in-crude oil emulsion include 30% water by volume and 70% Arabian crude oil by volume.

[0043] The Arabian crude oil includes 30 to 40 wt. %, preferably 31 to 39 wt. %, preferably 32 to 38 wt. %, preferably 33 to 37 wt. %, and preferably 34 to 36 wt. % aromatics, 35 to 40 wt. %, preferably 36 to 39 wt. %, and preferably 37 to 38 wt. % saturates, 10 to 20 wt. %, preferably 11 to 19 wt. %, preferably 12 to 18 wt. %, preferably 13 to 17 wt. %, and preferably 14 to 16 wt. % asphaltenes, and 10 to 20 wt. %, preferably 11 to 19 wt. %, preferably 12 to 18 wt. %, preferably 13 to 17 wt. %, and preferably 14 to 16 wt. % resins based on the total weight of the Arabian crude oil. In some embodiments, the Arabian crude oil includes 31 to 35 wt. %, preferably 31.5 to 34.5 wt. %, preferably 32 to 34 wt. %, and preferably 32.5 to 33.5 wt. % aromatics, 38 to 39 wt. %, preferably 38.2 to 38.8 wt. %, and preferably 38.4 to 38.6 wt. % saturates, 11 to 13 wt. %, preferably 11.2 to 12.8 wt. %, preferably 11.4 to 12.6 wt. %, preferably 11.6 to 12.4 wt. %, and preferably 11.8 to 12.2 wt. % asphaltenes, and 15 to 18 wt. %, preferably 15.5 to 17.5 wt. %, and preferably 16 to 17 wt. % resins based on the total weight of the Arabian crude oil. In a specific embodiment, the Arabian crude oil includes about 33.15 wt. % aromatics, about 38.44 wt. % saturates, about 12.10 wt. % asphaltenes, and about 16.32 wt. % resins based on the total weight of the Arabian crude oil.

[0044] In some embodiments, a viscosity of the Arabian crude oil is 14 to 16 mPa / s, preferably 14.1 to 15.9 mPa / s, preferably 14.2 to 15.8 mPa / s, preferably 14.3 to 15.7 mPa / s, preferably 14.4 to 15.6 mPa / s, preferably 14.5 to 15.5 mPa / s, preferably 14.6 to 15.4 mPa / s, preferably 14.7 to 15.3 mPa / s, preferably 14.8 to 15.2 mPa / s, more preferably 14.9 to 15.1 mPa / s, and preferably about 15 mPa / s. In a preferred embodiment, the viscosity of the Arabian crude oil is about 15.1 mPa / s. In some embodiments, a density of the Arabian crude oil is 0.88 to 0.89 kg / m3, preferably 0.881 to 0.889 kg / m3, preferably 0.882 to 0.888 kg / m3, preferably 0.883 to 0.887 kg / m3, and more preferably 0.884 to 0.886 kg / m3. In a preferred embodiment, the density of the Arabian crude oil is about 0.8843 kg / m3. In some embodiments, an API gravity of the Arabian crude oil is 28 to 28.5, preferably 28.1 to 28.4, and preferably 28.2 to 28.3. In a preferred embodiment, the API gravity of the Arabian crude oil is about 28.2. In a specific embodiment, the viscosity of the Arabian crude oil is about 15.1 mPa / s, the density is about 0.8843 kg / m3, and the API gravity is about 28.2.

[0045] In some embodiments, the aqueous solution is mixed with the water-in-crude oil emulsion for a period of 10 to 30 minutes, preferably 12 to 28 minutes, preferably 14 to 26 minutes, preferably 16 to 24 minutes, preferably 18 to 22 minutes, and yet more preferably about 20 minutes. In some embodiments, the mixing occurs for 15 to 25 minutes, preferably 16 to 24 minutes, preferably 17 to 23 minutes, preferably 18 to 22 minutes, more preferably 19 to 21 minutes, and yet more preferably 20 minutes. In some embodiments, the aqueous solution is mixed with the water-in-crude oil emulsion using at a speed of 600 to 800 rpm, preferably 620 to 780 rpm, preferably 640 to 760 rpm, preferably 660 to 740 rpm, more preferably 680 to 720 rpm, and yet more preferably about 700 rpm.

[0046] At step 54, the method 50 includes heating the emulsion mixture to a temperature of 65 to 75° C., preferably 66 to 74° C., preferably 67 to 73° C., preferably 68 to 72° C., more preferably 69 to 71° C., and yet more preferably about 70° C. for 12 to 24 hours, preferably 13 to 23 hours, preferably 14 to 22 hours, preferably 15 to 21 hours, preferably 16 to 20 hours, and preferably 17 to 19 hours. In some embodiments, the emulsion mixture is heated for 20 to 24 hours, preferably 21 to 23 hours, and more preferably about 22 hours at a temperature of 70° C. In some embodiments, the emulsion mixture is heated for 12 to 16 hours, preferably 13 to 15 hours, and more preferably about 14 hours at a temperature of 70° C. In a preferred embodiment, the emulsion mixture is heated for about 22 hours at a temperature of 70° C. In another preferred embodiment, the emulsion mixture is heated for about 14 hours at a temperature of 70° C. Heating the emulsion mixture may promote a coalescence of water droplets, reduce viscosity of crude oil, and enhance diffusion of ZnCl2 and mobility of water droplets.

[0047] At step 56, the method 50 includes sonicating the heated emulsion mixture for 20 to 140 minutes, preferably 25 to 135 minutes, preferably 30 to 130 minutes, preferably 35 to 125 minutes, preferably 40 to 120 minutes, preferably 45 to 115 minutes, preferably 50 to 110 minutes, preferably 55 to 105 minutes, preferably 60 to 100 minutes, preferably 65 to 95 minutes, preferably 70 to 90 minutes, and preferably 75 to 85 minutes. Sonication provides high-frequency sound waves (ultrasound) to agitate particles within a sample. Sonication may use sound energy to rupture an interfacial film and / or enhance phase separation. In some embodiments, the heated emulsion mixture is sonicated for 110 to 130 minutes, preferably 115 to 125 minutes, and more preferably about 120 minutes. In other embodiments, the heated sonication mixture is sonicated for 20 to 40 minutes, preferably 25 to 35 minutes, and more preferably about 30 minutes. In an embodiment, the mixing, the heating the emulsion mixture, and the sonicating the heated emulsion mixture are carried out in a mixing tank.

[0048] At step 58, the method 50 includes separating the sonicated heated emulsion to form an oil phase and a water phase. In some embodiments, the oil phase is separated on top of (i.e., above) the water phase. In some embodiments, the separating is carried out in a vertical separator column in sonic communication with a mixing tank in which the sonicating is carried out, and the vertical separator column has a heated emulsion inlet at a height no lower than ½ a height of the separator column measured from a bottom outlet to a top outlet. In some embodiments, the separation process is facilitated by transferring the heated emulsion mixture to a vertical separator column for phase separation. In some embodiments, the vertical separator column is in the shape of a cylinder. In some embodiments, the vertical separator column is in the shape of a cylinder and has a removable cap located at a top of the vertical separator column and a removable cap on a bottom of the vertical separator column. In some embodiments, the mixing tank is in the shape of a cylinder. In some embodiments, the mixing tank is in the shape of a cylinder and encloses at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least 90%, preferably at least 95%, preferably at least 99%, and preferably 100% of the vertical separator column in the shape of a cylinder. In other embodiments, the mixing tank is in the shape of a rectangular prism with an open top. In some embodiments, the mixing tank is in the shape of a rectangular prism with an open top and surrounds at least 20%, preferably at least 30%, preferably at least 40%, preferably at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, and preferably at least 90% of the vertical separator column in the shape of a cylinder. In some embodiments, the vertical separator column has a heated emulsion inlet at a height no lower than ½ (0.5), preferably no lower than ⅖, preferably no lower than ⅓, preferably no lower than ¼, preferably no lower than ⅕ a height of the vertical separator column from a bottom outlet to a top outlet. In some embodiments, the vertical separator column is connected to the mixing tank in a way that allows sonic energy (i.e., sonic communication) to continue influencing the emulsion during separation, promoting more efficient demulsification. In some embodiments, the emulsion enters the vertical separator column through a heated emulsion inlet that is positioned at a height no lower than halfway up the vertical separator column, measured from the bottom outlet to the top outlet. In some embodiments, the heated emulsion inlet may be programmed. In some embodiments, the heated emulsion inlet may be set at a consistent temperature. In other embodiments, the heated emulsion inlet may have a varied temperature. This elevated inlet position may allow for better gravity-based separation, helping the denser water phase settle at the bottom while the lighter oil phase rises to the top. In some embodiments, the emulsion breaks effectively into a water phase and an oil phase, which can then be collected separately from their respective outlets. The separated water can be removed by decantation or gravity settling.

[0049] The effectiveness of a method of a demulsification method may be determined by measuring dehydration efficiency (DE) DE refers to a percentage of water removed from a water-in-crude oil emulsion during a demulsification process (i.e., by the method of the present disclosure). Two factors that may affect the dehydration efficiency (DE) of the demulsification mixture are the temperature and time at which the emulsion mixture is heated and the duration of sonication applied to the heated emulsion mixture. In an embodiment, the emulsion mixture is heated for 22 hours, the heated sonication mixture is sonicated for 2 hours, and the dehydration efficiency of the demulsification mixture is from 85 to 95%, preferably 86 to 94%, preferably 87 to 93%, preferably 88 to 92%, and preferably 89 to 91% based on the volume of water. In a specific embodiment, the emulsion mixture is heated for 22 hours, the heated sonication mixture is sonicated for 2 hours, and the dehydration efficiency of the demulsification mixture is about 100% based on a volume of water. In some embodiments, the emulsion mixture is heated for 14 hours, the heated sonication mixture is sonicated for 0.5 hours (30 minutes), and the dehydration efficiency of the demulsification mixture is from 35 to 45%, preferably 36 to 44%, preferably 37 to 43%, preferably 38 to 42%, and preferably 39 to 41% based on the volume of water.EXAMPLES

[0050] The following examples describe and demonstrate a method of demulsifying a water-in-crude oil emulsion as described herein. The examples are provided solely for illustration and are not to be construed as limitations of the present disclosure, as many variations thereof are possible without departing from the spirit and scope of the present disclosure.Example 1: Experimental

[0051] Zinc chloride (ZnCl2) was purchased from Sigma Aldrich and used as is. Crude oil from Saudi Arabia was obtained from Uthmania (Uth) reservoir. The saturates, aromatics, resins, and asphaltenes (SARA) characterization of the crude is presented in Table 1. Deionized water (DI) obtained from a Milli-Q system was used in emulsion preparation.TABLE 1SARA analysis of the crude oilContent (wt. %)DensityAPIViscositySatu-Asphal-(kg m−3)gravity(mPa / s)AromaticsratestenesResins0.884328.215.133.1538.4412.116.32

[0052] Emulsion Preparation: Lab made emulsions were prepared by transferring the crude oil to a 50 mL beaker and adding the aqueous phase (DI water or ZnCl2 solution) dropwise at 30\70 (water\oil) ratio. An overhead stirrer was then used at 700 revolutions per minute (rpm) for 20 minutes to mix the crude oil and aqueous phase to form the emulsion.

[0053] Addition of zinc chloride: Incorporating the ZnCl2 within the emulsion itself by mixing the crude oil with ZnCl2 solution in different ZnCl2 concentrations was prepared as follows: Each bottle contains 4 mL of lab-made emulsion (30% DI Water or brine, 70% crude oil).

[0054] Zn: 30,000:30,000 ppm ZnCl2 solution (0.75 wt. %)

[0055] DI: 0 ppm ZnCl2 solution (DI only)Example 2: Effect of Adding ZnCl2 on Demulsification

[0056] The effect of adding ZnCl2 for demulsifying crude oil emulsions was investigated via conducting a demulsification experiment, as shown in FIG. 2. To conduct the experiment two lab-made emulsions were prepared at 30% water cut. In the demulsification experiment, the emulsion was subjected to high temperature, where one emulsion sample contains 30,000 parts per million (ppm) of ZnCl2 and the second one was free of ZnCl2. The temperature was maintained at approximately 70° C. The dehydration efficiency (DE %) was calculated according to equation 1:DE⁢ %=(V / V0)×100(1)V represents the volume of water that is separated from the emulsion and V0 denotes the initial volume of water. After heating the emulsion for 14 hours at a temperature of 70° C. and applying 30 minutes of sonication, around 40% dehydration was achieved. By prolonging the heating time to 22 hours and increasing the sonication duration to 2 hours, nearly 100% dehydration was accomplished, as be seen in FIG. 2.Demulsification performances of crude oil emulsions using an addition of zinc chloride (ZnCl2) as a demulsifier was analyzed. Addition of the bivalent cation destabilized the emulsion within hours under high temperature and sonication, facilitating the separation process of oil and water phases. The findings highlight the used of ZnCl2 as a demulsifier for crude oil emulsions. The rapid and efficient demulsification observed in the disclosure indicates that the bivalent cation may find practical applications in various industries, including petroleum, chemical, and wastewater treatment. By improving the separation efficiency of oil-water emulsions, the demulsifier may contribute to enhanced processing, oil recovery, and overall operational efficiency.

[0058] Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced otherwise than as specifically described herein.

Claims

1. A method of demulsifying a water-in-crude oil emulsion, comprising:mixing an aqueous solution consisting of water and 0.5 to 1 percent by weight (wt. %) zinc chloride with the water-in-crude oil emulsion to obtain an emulsion mixture,wherein percent by weight is based on a total weight of the aqueous solution,wherein the water-in-crude oil emulsion comprises 28 to 32% water by volume and 68 to 72% Arabian crude oil by volume,wherein the Arabian crude oil comprises 30-40 wt. % aromatics, 35-40 wt. % saturates, 10-20 wt. % asphaltenes, and 10-20 wt. % resins based on the total weight of the Arabian crude oil,heating the emulsion mixture to a temperature of 65 to 75° C. for 12 to 24 hours;sonicating the heated emulsion mixture for 20 to 140 minutes; andseparating the sonicated heated emulsion to form an oil phase and a water phase.

2. The method of claim 1, wherein the zinc chloride is present in the aqueous solution in an amount of 0.6 to 0.8 wt. %, and wherein the separating is carried out in a vertical separator column in sonic communication with a mixing tank in which the sonicating is carried out, wherein the vertical separator column has a heated emulsion inlet at a height no lower than ½ a height of the vertical separator column measured from a bottom outlet to a top outlet.

3. The method of claim 1, wherein the zinc chloride is present in the aqueous solution in an amount of 0.74 to 0.76 wt. %.

4. The method of claim 1, wherein the mixing occurs for 10 to 30 minutes.

5. The method of claim 1, wherein the mixing occurs for 15 to 25 minutes.

6. The method of claim 1, wherein the heating occurs at a temperature of 68 to 72° C.

7. The method of claim 1, wherein the heating occurs at a temperature of 70° C.

8. The method of claim 1, wherein the heating occurs for 22 hours, the sonicating occurs for 2 hours, and a dehydration efficiency of the demulsification mixture is from 85 to 95% based on a volume of water.

9. The method of claim 1, wherein the heating occurs for 14 hours, the sonicating occurs for 30 minutes, and a dehydration efficiency of the demulsification mixture is from 35 to 45% based on a volume of water.

10. The method of claim 1, wherein the water-in-crude oil emulsion comprises 30% water by volume and 70% Arabian crude oil by volume.

11. The method of claim 1, wherein a density of the Arabian crude oil is 0.88 to 0.89 kg / m3.

12. The method of claim 1, wherein an API gravity of the Arabian crude oil is 28 to 28.5.

13. The method of claim 1, wherein a viscosity of the Arabian crude oil is 14 to 16 mPa / s.

14. The method of claim 1, wherein the mixing occurs at a speed of 600 to 800 rpm.

15. The method of claim 1, wherein the crude oil is an external phase.

16. The method of claim 1, wherein the Arabian crude oil comprises 31-35 wt. % aromatics, 38-39 wt. % saturates, 11-13 wt. % asphaltenes, and 15-18 wt. % resins based on the total weight of the Arabian crude oil.

17. The method of claim 1, wherein the sonicating occurs for 20 to 40 minutes.

18. The method of claim 1, wherein the sonicating occurs for 110 to 130 minutes.

19. The method of claim 1, wherein the heating occurs for 20 to 24 hours.

20. The method of claim 1, wherein the heating occurs for 12 to 16 hours.

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