Demulsifier compositions for low temperature demulsification of waxy crude oil emulsions

Abstract

The present invention is envisioned for a demulsifier composition for low temperature demulsification of waxy crude oil emulsion, wherein the low temperature implies all temperatures above pour point of the emulsion and up to 10℃ below the pour point of the emulsion. The composition comprises of two chemical surfactants to demulsify a stable crude oil emulsion, and a second surfactant is a high HLB (HLB > 13) surfactant molecule wherein, a first surfactant is a medium HLB (9-14) surfactant molecule with two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group (π shaped); and a second surfactant is a high HLB (HLB >13) surfactant molecule which is single tailed ionic or non-ionic surfactant.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to demulsification of crude oil emulsions. In specific, the present invention relates to demulsifier compositions for low temperature demulsification of waxy crude oil emulsion, wherein the low temperature implies all temperatures above pour point of the emulsion and up to 10°C below the pour point of the emulsion, where below pour point temperatures, high shear mixing may be required before settling.BACKGROUND OF THE INVENTION

[0002] Demulsification is the process of separating emulsions, which are mixtures of oil and water stabilized by emulsifiers. There are several techniques used in the oil industry todemulsify crude oil. Here are a few commonly employed methods:

[0003] 1. Chemical Demulsifiers: Chemical demulsifiers are the most widely used approach for demulsifying crude oil. These chemicals are designed to disrupt the emulsion by reducing the interfacial tension between the oil and water phases. They work by adsorbing ontothe oil-water interface and destabilizing the emulsion, allowing for easy separation. The selection of the demulsifier depends on the specific characteristics of the emulsion.

[0004] 2. Heating: Heat can be applied to increase the effectiveness of demulsification. By heating the emulsion, the viscosity of the oil phase decreases, and the water droplets coalesce, making it easier to separate the two phases. However, excessive heating is not very economical. Also, as the oil well ages, the water content increases, and the temperature in the heater-treater system drops eventually.

[0005] 3. Electrostatic Coalescence: This method utilizes electrical fields to coalesce water droplets within the emulsion. By applying a high voltage to the emulsion, the dispersed water droplets become charged, and like charges repel each other, causing coalescence. The larger water droplets can then be easily separated from the oil phase.

[0006] 4. Mechanical Methods: Mechanical methods involve physical agitation or separation to break the emulsion. This can include techniques such as centrifugation, filtration, or gravity settling. Centrifugation uses centrifugal force to separate the phases based on their densities, while filtration involves passing the emulsion through porous media to trap and filter out the water phase. Gravity settling allows the emulsion to stand undisturbed, allowing for natural separation due to the differences in density between the oil and water.

[0007] 5. Combination Techniques: In many cases, a combination of demulsification techniques is required to effectively separate the emulsion. For instance, chemical demulsifiers may be used in conjunction with heat or mechanical methods to enhance separation efficiency and reduce processing time.

[0008] While electrostatic coalescence is an effective demulsification technique, it also has some inherent disadvantages. Here are a few drawbacks associated with electrostatic coalescence:

[0009] 1. High Energy Consumption: Electrostatic coalescence requires a significant amount of energy to generate the necessary electrical fields. This can result in high operational costs, especially when processing large volumes of crude oil.

[0010] 2. Equipment Complexity: The equipment used for electrostatic coalescence can be complex and require careful design and maintenance. Electrodes, transformers, and high- voltage systems are typically needed, which adds to the complexity and cost of the demulsification process.

[0011] 3. Sensitivity to Impurities: Electrostatic coalescence can be adversely affected by impurities present in the crude oil emulsion. Substances like salts, solids, and fine particles can interfere with the performance of the electrical fields, reducing the efficiency of coalescence. Pre-treatment processes may be required to remove or minimize impurities before applying electrostatic coalescence.

[0012] 4. Limited Flexibility: Electrostatic coalescence may not be suitable for all types of crude oil and emulsions. The efficacy of the technique depends on the properties of the emulsion and the electrical properties of the oil-water interface. Emulsion characteristics, such as water droplet size and stability, can influence the effectiveness of electrostatic coalescence.

[0013] 5. Environmental Considerations: Depending on the energy sources used to generate the electrical fields, electrostatic coalescence can have environmental implications. If non-renewable energy sources are employed, it may contribute to carbon emissions and other environmental concerns.

[0014] Despite these disadvantages, electrostatic coalescence remains a valuable demulsification method and is often used in combination with other techniques to optimize separation efficiency and reduce processing time.

[0015] There are serious disadvantages of Mechanical Method enumerated below:-

[0016] 1. Cost: Mechanical methods often require specialized equipment or machinery, which can be expensive to purchase, maintain, and operate.

[0016] 2. Limited applicability: Certain mechanical methods might not be suitable for all situations or conditions. They may work effectively in some cases but not in others, limiting their overall usefulness.

[0017] 3. Environmental impact: Some mechanical methods can have negative effects on the environment. For example, heavy machinery used in construction projects can cause soil erosion, habitat destruction, or noise pollution.

[0018] 4. Labor-intensive: Some mechanical methods require a significant amount of manual labor. This can increase costs and lead to worker fatigue or injuries.

[0019] 5. Maintenance requirements: Mechanical methods typically require regular maintenance to ensure they function properly. This can add additional costs and downtime if equipment needs repairing or replacement parts.

[0020] 6. Energy consumption: Many mechanical methods rely on power sources such as electricity or fuel. This consumption of energy can contribute to environmental concerns and increase operational costs.

[0021] It's important to note that the disadvantages may vary depending on the specific mechanical method being used.

[0022] Low temperature demulsification of crude oil emulsion containing high concentration of wax is rendered very difficult due to Pickering stabilization by wax particles. Pickering stabilization is caused by a3film of aggregate of solid particles covering the interface between a dispersed phase and a continuous phase. The presence of these solid particles causes these emulsions to be extremely stable.

[0023] Pickering stabilization occurs during the transport of crude oil from the well to the platform through the low temperature sea-bed where the emulsion gets cooled well below the Wax Appearance Temperature (WAT). The wax, while precipitating out, picks up resins and / or asphaltenes which impart a certain degree of amphiphilicity to the wax particles. This allows them to grow and form a network at the oilwater interface around the water droplets. This imparts high stability to the water in crude oil emulsions. In order to demulsify this emulsion, the wax network needs to be broken and then displaced from the interface into either of the bulk phases. This should be followed by phase inversion.PRIOR ART DISCUSSION1. Patent No. CN113699809Title:Method for preparing W / C reversed micelles by using low-cost Pickering emulsifier and dyeing method.Description:The W / C reversed micelles are prepared by magnetically stirring a lipophilic Pickering particle emulsifier, an anionic surfactant, carbon dioxide and deionized water in a high-pressure visible reactor at a high speed of 800- 1500rpm, the W / C reversed micelles are applied to natural fiber dyeing, and the dye is a conventional water-soluble dye. The lipophilic particles comprise titanium dioxide, aluminum oxide, polytetrafluoroethylene, carbon black, coal powder ground by coal and the like, the anionic surfactant comprises sodium disulfosuccinate, namely 2- ethylhexyl, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate and the like.However, apart from their application being based on dyeing, they are trying to form a stable Pickering emulsion.Differences with current Invention:This invention, on the other hand is trying to destabilize a Pickering emulsion, using both anionic and cationic surfactants such as Dioctyl sulfosuccinate sodium , sodium dodecyl benzene sulfonate etc.2. Patent No. US10131830B1Title:Method for preventing formation of water-oil emulsions using additivesDescription:A method of preventing formation of a water and oil emulsion in a downhole formation containing oil. The method comprises preparing a dispersion of water and a plurality of non- functionalized nanoparticles, each nanoparticle in the plurality of nanoparticles having a size of at least 300 nanometres and injecting the dispersion into contact with the oil downhole. Presence of the plurality of nanoparticles prevents formation of an emulsion between the injected water and the oil.4Differences with current Invention:This invention deals with separation of Pickering emulsions, instead of preventing the formation of emulsion. Also, this invention is not using nanoparticles-based additives. Instead, this invention proposes a combination of 2 chemical surfactants to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.3. Patent No. EP2741847B 1Title:Novel Method for destabilizing a Pickering emulsion.Description:A continuous phase chosen from alcohol or water; and the dispersed phase is chosen from mineral oil, a fluorinated oil, a fatty acid or a (meth) acrylate oligomer, and preferably a mineral oil consisting of a mixture of hydrocarbons, or a (meth) acrylate oligomer chosen from tri(propylene glycol) diacrylate (TPGDA), ethylene glycol dimethacrylate, poly(ethylene glycol) diacrylate (PEGDA), pentaerythritol triacrylate, trimethylolpropane triacrylate (TMPTA) and 1,6-hexanediol diacrylate. Nanoparticles of silica, gold, iron oxide, cerium oxide, titanium dioxide, clay or quantum dots having a diameter between 10 and 50 nm.The nanoparticles are silica modified on the surface by etherification of the silanol groups by an alcohol, or by grafting an organosilane to their surface. The layer of nanoparticles is destabilized by altering the hydrophilic / hydrophobic balance of the continuous phase: by injecting a miscible liquid with the continuous phase. The injection of the solvent can be done either by simple addition using a micropipette or under controlled flow using a syringe drive The miscible solvent being: water when the continuous phase is an alcohol of formula R-OH where R is a C 1 to C 4 hydrocarbon chain. This will make the continuous phase more hydrophilic, or an alcohol of formula R-OH where R is a hydrocarbon chain C 1 to C 8 , and preferably C 1 to C 4 , when the continuous phase is water; to render the continuous phase more hydrophobic.Differences with current Invention:This invention is not dealing with synthetic Pickering emulsions stabilized by nanoparticles. Instead, it deals with Pickering emulsions stabilized by wax.Also, the method of destabilization adopted by EP2741847B1 patent discusses addition of a miscible phase / liquid (water / alcohol) to the continuous phase to alter the HLB of the continuous phase and hence promote coalescence.However, this invention recommends a minimum of 2 surfactants that enable the coalescence of the Pickering emulsion containing waxes on the interface. One of the surfactants will help in removing the wax particle from the interface while the other helps in coalescence by inducing phase inversion.This Invention proposes a combination of 2 chemical surfactants to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably5ionic / non-ionic head group, (a shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.4. Patent No.: US4592849ATitle:Method for removing water from produced crude oilDescription:A method for removing emulsified water from a crude oil stream produced from a subterranean, oilcontaining formation, the oil stream containing about 65% by volume of emulsified water consisting essentially of:(a) passing the crude oil stream containing emulsified water through a bed of a water-saturated hydrophilic coalescing medium selected from the group consisting of sand, crushed quartz, diatomaceous earth, porous silica and ground walnut shells, whereby the water coalesces and an oil phase, substantially free of water, and a water phase are formed; and(b) separating the oil phase containing less than 3 volume percent of water from the water phase by gravitational separation or centrifuging.Differences with current Invention:Patent US4592849A discusses a method of physical separation of water from the emulsion. Also they do not deal with Pickering emulsionsHowever, this invention proposes to demulsify a Pickering emulsion to chemically separate the emulsion using chemical surfactants that help in effectively breaking an emulsion.5. Patent No.: US 10131830B1Title:Method for preventing formation of water-oil emulsions using additivesDescription:A method of preventing formation of a water and oil emulsion in a downhole formation containing oil, the method comprising: preparing a dispersion of water and a plurality of non-functionalized nanoparticles by sonication, each nanoparticle in the plurality of nanoparticles having a size of 300-500 nanometers; and injecting the dispersion into contact with the oil downhole, wherein presence of the plurality of nanoparticles prevents formation of an emulsion between the injected water and the oil. wherein the plurality of non-functionalized nanoparticles comprise silica and have respective surfaces that are free of any surface modification. They lack any chemical groups which modify the surface properties of the silica.6The nanoparticles of over 300 nanometers in size are suitable to demulsify water from oil without functionalization, and, more specifically, free of (without) any surface modification with additional chemical species.Differences with current Invention:This invention works with Pickering emulsions.Also, instead of trying to prevent the formation of emulsions by addition of additives, this invention proposes to destabilize a stable emulsion using chemical surfactants instead of nanoparticles.Also, this invention proposes a combination of 2 chemical surfactants to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.6. Patent No.:US6189613BlTitle:Downhole oil / water separation system with solids separationDescription:A method for separating downhole oil well production fluid from a production zone of a subterranean formation, wherein said fluid contains oil, water and solids comprising: a. delivering the production fluid to a liquid / solid separator; b. separating the production fluid in the liquid / solid separator into a solids enriched stream and an oil and water enriched stream; c. delivering the oil and water enriched stream to a liquid / liquid cyclone separator; and d. separating the oil and water enriched stream in the liquid / liquid cyclone separator into an oil enriched stream at the cyclone overflow and a water enriched stream at the cyclone underflow.It requires a liquid / liquid cyclone adapted to receive the oil and water enriched stream as overflow from the liquid / solid cyclone and separate said stream into an oil enriched stream at an overflow outlet of said cyclone and a water enriched stream at an underflow outlet of said outlet;Differences with current Invention:Invention under this patent is performing physical separation using a cyclone separator.However, this invention deals with chemical separation of an emulsion, i.e. destabilizing a stable emulsion using chemical surfactants.7. Patent No.: US5762138ATitle:Method of preventing incompatibility between aqueous well treating fluids and hydrocarbonsDescription:7The patent discloses the use of a microemulsion surfactant additive for use in aqueous well treating fluids to prevent the formation of stable emulsions and sludge when the aqueous treating fluids contact hydrocarbons comprising: a solvent selected from the group consisting of hexylene glycol, other glycols having in the range of from 1 to about 10 carbon atoms and glycol ethers having in the range of from 1 to about 10 carbon atoms; a co-solvent selected from the group consisting of isopropyl alcohol, other branched alkyl alcohols having in the range of from 1 to about 10 carbon atoms and linear alkyl alcohols having in the range of from 1 to about 10 carbon atoms; water; an aqueous liquid-hydrocarbon liquid de-emulsifying surfactant comprised of an alkyldiphenyloxide sulfonic acid; and liquid hydrocarbon anti sludging surfactant selected from the group consisting of alkylbenzene and alkyl naphthalene sulfonic acids and salts.Differences with current Invention:This invention proposes the use of only 2 surfactants to demulsify a stable emulsion, i.e. a medium HLB (8.5- 11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non- ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non- ionic surfactant.8. Patent No.: CN107141429Title:Modified magnetic nano-silica and application thereof in oil-water separation.Description:Pickering emulsifying agent solids particle - Modified magnetic nano silicon is prepared and utilised in separation of oil-water emulsion. After the addition of the magnetic modified nano silicon to the emulsion, the mixed system is placed in variable magnetic field, magnetic field intensity is changed, particle emulsion droplets assemble, clear liquid part is removed, magnetic field intensity is further increased, particle emulsion droplets coalesce, and ultimately the modified magnetic nanometer silicon dioxide particle is recovered.Differences with current Invention:There is use of electrical fields in the patent CN107141429 for the demulsification / dewatering process.However, this invention proposes the use of a combination of 2 chemical surfactants to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.9. Patent No.: (CN113292984)Title:Pickering emulsion with CO2 / double -response type surfactant and preparation method of Pickering emulsion demulsification by introducing CO2Description:8Mixing a carboxyl modified nanometer silicon dioxide particles and CO2 to prepare a redox dual-response type surfactant. This is then mixed into an oil-water two-phase according to a certain proportion and emulsified through a vortex oscillation instrument at a certain rotating speed to obtain the emulsion.The resultant Pickering emulsion has good stability. For demulsifying the Pickering emulsion, CO2 (or any alternative oxidant) is added to break the emulsion. Introducing N2 into the emulsion or a reducing agent reproduces a stable emulsion.Differences with current Invention:This invention does not deal with a synthetic Pickeirng emulsion that is stabilized by silica nanoparticles. Instead, it deals with Pickering emulsion that is stabilized by wax particles, which is not responsive to addition of CO2 / N2. This invention proposes a combination of 2 chemical surfactants to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non- ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.10. Patent No.: WO 2009 / 023724Title:Method for separating crude oil emulsionsDescription:The patent discloses a set of formulations composed of one or more terpene alkoxylates and optionally one or more anionic or nonionic surfactants. The anionic surfactants are comprised of anionic alkyl sulfosuccinates, alkyl phosphonic acids and their salts and any combinations of them; the non ionic surfactants are selected from the group of copolymers of polyethylene oxide / polypropylene oxide, ethoxylated fatty acid of polyethylene glycol, modified alkanolamides and alkoxylated terpenes (FIG. 3), alone or in combinations thereof.Differences with current Invention:The current invention does not deal with terpene alkoxylates based surfactants as suggested by WO 2009 / 023724A combination of 2 chemical surfactants is proposed to demulsify a stable emulsion, i.e. a medium HLB (8.5- 11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non- ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non- ionic surfactant.11. Patent No.: US9404052B2:Title:Dehydrating and desalting median, heavy and extra-heavy oils using ionic liquids and their formulationsDescription:9The invention relates to the application of different families of IL's and their formulations in the demulsification of median, heavy and extra-heavy crude oils which API gravities are within the range of 8 to 30. The asphlatene content in these crude oil ranges from 11-24%.The invention is directed to the use of ionic liquids dissolved in solvents having a boiling point in the range from 35° C to 200° C., preferably dichloromethane, chloroform, methanol, isopropanol, ethanol, benzene, toluene and xylenes, individually or in mixtures of them; when they are used in concentrations from 50 ppm to 2000 ppm, preferably from 600 ppm until 1750 ppm, to break water in oil emulsions and simultaneously desalt crude oils having and API gravity between 30 and 8°. The ionic liquid is selected from the group consisting of trihexylmethylammonium methylsulfate, trioctylmethylammonium ethyl sulfate, trioctylmethylammonium methylsulfate, and mixtures thereof.Differences with current Invention:The current invention does not deal with ionic liquids such as trihexylmethylammonium methylsulfate, trioctylmethylammonium ethyl sulfate, trioctylmethylammonium methylsulfate, and mixtures thereof.Also, the patent deals with crude oil having asphaltene concentrations < 1%. Asphaltenes are not the major stabilizing component in crude oil. The current invention works on Pickering crude oil emulsions with wax stabilized interface.A combination of 2 chemical surfactants is proposed under the current invention to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.Title:DEMULSIFYING COMPOSITIONS AND METHODS OF USECA 2881292This invention provides:Methods for resolving emulsions in a hydrocarbon stream by contacting the hydrocarbon stream with a demulsifying composition are disclosed. Demulsifying compositions for treating a hydrocarbon stream are also disclosed, wherein the demulsifying composition comprises at least one C4-C12 alkyl phenolformaldehyde resin alkoxylate.Differences with current Invention:In the proposed invention, we do not deal with demulsifying compositions comprising of at least one C4-C12 alkyl phenol-formaldehyde resin alkoxylate.Instead, we propose a combination of 2 chemical surfactants under the current invention to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.10Title:DEMULSIFYING COMPOSITIONS AND METHODS FOR SEPARATINGEMULSIONS USING THE SAME.US 2013 / 0299390 AlThis invention provides:The present invention provides for a demulsifying composition comprising the reaction product of an oxirane or oxetane compound (I) comprising at least two oxirane or oxetane groups; a compound (II) comprising silicon and one or more amino groups; and optionally a poly amine (III); and a secondary amine (IV).Differences with current Invention:In contrast to the patent US 2013 / 0299390 Al, the current invention does not specify demulsifiers comprising the reaction product of an oxirane or oxetane compound (I) comprising at least two oxirane or oxetane groups; a compound (II) comprising silicon and one or more amino groups; and optionally a poly amine (III); and a secondary amine (IV).Instead, we propose a combination of 2 chemical surfactants under the current invention to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.Title:DEMULSIFICATION COMPOSITIONS, SYSTEMS AND METHODS FOR DEMULSIFYING AND SEPARATING AQUEOUS EMULSIONSUS 9308474 B2This invention provides:The present invention provides compositions, systems and methods for demulsifying an emulsion including an aqueous phase and an organic phase by adding an effective amount of a composition comprising at least one quaternary organopolysiloxane or salt thereof to the emulsion, the composition optionally including at least one of quaternary epihalohydrin / polyamine copolymers or salts, and / or (poly) diallyldimethylammonium halides.Differences with current Invention:In contrast to the patent US 9308474 B2, the current invention does not specify demulsifiers comprising at least one quaternary organopolysiloxane or salt thereof to the emulsion, the composition optionally including at least one of quaternary epihalohydrin / polyamine copolymers or salts, and / or (poly) diallyldimethylammonium halides.Instead, a combination of 2 chemical surfactants is proposed under the current invention to demulsify a stable emulsion, i.e. a medium HLB (8.5-11) surfactant which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group, (n shaped); and a high HLB surfactant which should preferably be Single tailed ionic / non-ionic surfactant.NON-PATENT PRIOR ART1. Title:Hassanshahi N, Hu G, Li J. Investigation of Dioctyl Sodium Sulfosuccinate in Demulsifying Crude Oil-in- Water Emulsions. ACS Omega. 2022 Sep 8;7(37):33397-33407.Description:The authors have used Dioctyl Sodium Sulfosuccinate to demulsify their crude oil emulsion. However, the emulsion was asphaltene rich (20wt%) and the authors have synthesized the emulsion from crude oil. Hence it is not a case of Pickering emulsion.Differences with current invention:The current invention deals with Pickering crude oil emulsions that have very low asphaltene content (0.038%). This quantity of asphaltene is insufficient to stabilize an emulsion. The major stabilizing factor is waxes in our crude oil.Also, a combination of 2 surfactants are proposed by the current invention.Dioctyl Sodium Sulfosuccinate is unable to destabilize the emulsion by itself. The presence of a phase inverting agent (namely SDS, SDBS, CT AB) is also required in order to enable demulsification2. Title:C.S. Shetty, A.D. Nikolov, D.T. Wasan & B.R. Bhattacharyya (1992) Demulsification Of Water In Oil Emulsions Using Water Soluble Demulsifiers, Journal of Dispersion Science and Technology, 13:2, 121-133 Description:The authors have proposed the use of a water soluble demulsifier, sodium dodecyl sulfate(SDS) for destabilizing a synthetic water in heptol emulsion that is heavily stabilized by asphaltene. The author tries to destabilize the emulsion by application of Bancroft’s rule, such that the type of emulsion formed will majorly depend on the solubility of the surfactant. The phase in which the stabilizing agent / surfactant is soluble will become the continuous phase. So asphaltenes which are oil soluble tend to favor water in oil emulsion. However, on the addition of a SDS, the W / O emulsion breaks and tends to favor the formation of a O / W emulsion.However, the emulsion has no wax content and hence is not a Pickering emulsion.Differences with current invention:The current invention deals with wax stabilized Pickering emulsions. In the presence of this wax film, the use of SDS alone will not be effective, and does little to destabilize the emulsion by itself. SDS is effective only after the wax film is displaced from the interface.Oil emulsions and the different recent demulsification techniques in the petroleum industry-A reviewS M Abed*, NH Abdurahman, R M Yunus, H A Abdulbari, S AkbariFaculty of Chemical and Process Engineering Technology, Universiti Malaysia Pahang, 26300 Gambang, Kuantan, Pahang, MalaysiaAbstract:The emulsions are formed during the production of crude oil, which is often accompanied by water. These emulsions are undesirable and should treat to remove the dispersed water and accompanying inorganic salts. So, many researchers have over the years focused to probe of the appropriate demulsification techniques in the petroleum sector in order to meet production and transportation requirements, and to reduce corrosion and catalyst poisoning and to maximize the overall profitability of the crude oil production. Therefore, this study presents an overview of the emulsions, formations, classification, Stability, and properties practical demulsification techniques in the petroleum sector, including chemical, microwave irradiation, biological, thermal, membrane, electrical, and ultrasonic techniques for both oilfield and synthetic emulsions. Amongst these techniques, chemical demulsification has been the most widely applied and reported in the literature. Moreover, a more effective demulsification process could be attained by leveraging synergistic effects by combining one or more of these techniques.The research article summarizes the recent chemical demulsification compositions reported, including various anionic, cationic and non-ionic surfactants, magnetic graphene oxide, alginate, polyethers and ionic liquids. These have been employed in either Oil in water emulsions or water in oil emulsions. The concentration of the demulsifiers enlisted varies from 5ppm - 5000 ppm. The separation time required for good demulsification ratio varies from a contact time of 45 min to 30 hrs.Differences with current invention:

[0024] In the current invention, we have enlisted combination of two surfactants that are effective within 15 minutes and at ambient temperatures, unlike those mentioned in the research article. Also, our demulsifier combinations are effective even in the absence of centrifugation.

[0025] Currently, demulsification is rendered difficult because of low temperature attainable in the heater treater. This requires chemical demulsifiers that can help in demulsification at lower temperatures i.e., all temperatures above pour point of the emulsion and up to 10°C below the pour point of the emulsion, where below pour point temperatures, high shear mixing may be required before settling.

[0026] However, current demulsifiers used in the field are not effective at these temperatures. Therefore, there exists a need to develop a composition of demulsifiers for low temperature demulsification of waxy crude oil emulsion, wherein the low temperature implies all temperatures above pour point of the emulsion and up to 10°C below the pour point of the emulsion, where below pour point temperatures, high shear mixing may be required before settling.OBJECTIVE OF THE INVENTION

[0027] The main objective of the present invention is to provide an effective composition of suitable, demulsifiers for low temperature demulsification of waxy crude oil emulsion, wherein the low temperature13implies all temperatures above pour point of the emulsion and up to 10°C below the pour point of the emulsion, and where, below pour point temperatures, high shear mixing may be required before settling.

[0028] Yet another objective of the present invention is to provide suitable demulsifiers, wherein the demulsifier should be a mixture of Medium Hydrophilic -Lypophilic Balance (HLB) and High Hydrophilic- Lypophilic Balance (HLB).

[0029] These and other objectives of the present invention will be apparent from descriptions herein. Every objective of the invention is attained by at least one embodiment of the invention. However, no embodiment necessarily meets every objective set forth herein.SUMMARY OF THE INVENTION

[0030] The present invention provides for low temperature demulsification of waxy crude oil emulsion, wherein the low temperature implies all temperatures above pour point of the emulsion and up to 10°C below the pour point of the emulsion, where below pour point temperatures, high shear mixing may be required before settling.

[0031] In accordance with the objectives, the present invention provides a combination of 2 chemical surfactants to demulsify a stable emulsion, i.e., a medium HLB (9-14) surfactant molecule which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non-ionic head group. (T / n shaped); and a high HLB surfactant molecule which should preferably be single or double tailed ionic / non-ionic surfactant.

[0032] In a preferred embodiment of the present invention, the suitable demulsifiers that are effective at lower temperatures above the pour point of the emulsion and up to 10°C below the pour point of the emulsion such that high shear homogenization is applied, before settling of the emulsion takes place.

[0033] The composition of surfactants can separate water even at temperatures below the pour point of the waxy crude oil emulsions. In the case of temperatures less than the pour point temperature of the crude oil, hand shaking will be ineffective in enabling proper mixing of the crude oil. In such cases, mixing assisted by homogenization needs to be employed.

[0034] The specified combination of surfactants must have following characteristics: a) The demulsifier should be a mixture of Medium HLB surfactant molecule and High HLB surfactant molecule. b) The structure of the medium HLB (9 -14) surfactant molecule should be such that it has two hydrophobic - tails (double tailed) and preferably an ionic / non-ionic head group (preferably T-shaped / n shaped), including gemini surfactants. c) The high HLB (preferably HLB > 13) surfactant molecule should be single (or Double) tailed ionic / non-ionic surfactant. d) An anionic, oil soluble, double - tailed surfactant (preferably T shapcd / a shaped) can work with an anionic high HLB (phase - inverting) surfactant or a non-ionic surfactant. However, it14will not work in combination with a cationic high HLB (phase - inverting) surfactant because of the formation of salt between cationic and anionic surfactant. e) Similarly, a cationic, oil soluble, double tailed surfactant (preferably T shaped / n shaped) can work with a cationic high HLB (phase - inverting) surfactant or a non-ionic surfactant. However, it will not work in combination with an anionic high HLB (phase - inverting) surfactant because of the formation of salt between cationic and anionic surfactant. f) However, a non-ionic, oil soluble, double tailed surfactant (preferably T shaped / n shaped) can work with either a cationic high HLB (phase - inverting) surfactant or a non-ionic high HLB (phase - inverting) surfactant, or an anionic high HLB (phase - inverting) surfactant.

[0035] As should be apparent, the present invention can provide a number of advantageous features and benefits. It is to be understood that, in practising the invention, an embodiment can be constructed to include one or more features or benefits of embodiments disclosed herein but not others. Accordingly, it is to be understood that the preferred embodiments discussed herein are not to be construed as limiting, particularly since embodiments can be formed to practise the invention that do not include each of the features of the disclosed examples.BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Fig. 1 Structure of medium HLB, double tailed surfactant (a) Gemini surfactant and (b) single head group, double tailed surfactantDETAILED DESCRIPTION OF THE INVENTION

[0037] For a thorough understanding of the present disclosure, reference is to be made to the following detailed description, including the appended claims, in connection with the above-described drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art that the present disclosure can be practiced without these specific details. In other instances, structures and devices are shown in block diagrams form only, in order to avoid obscuring the disclosure.

[0038] Reference in this specification to “one embodiment,” “an embodiment,” “another embodiment,” “various embodiments,” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearance of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but may not be of other embodiment’s requirement.15

[0039] The present invention is envisioned for low temperature demulsification of waxy crude oil emulsion, wherein the low temperature implies all temperatures above pour point of the emulsion and up to 10°C below the pour point of the emulsion, where below pour point temperatures, high shear mixing may be required before settling.

[0040] In the case of temperatures less than the pour point temperature of the crude oil, hand shaking will be ineffective in enabling proper mixing of the crude oil. In such cases, mixing assisted by homogenization needs to be employed.

[0041] This involves the preparation of a combination of 2 chemical surfactants to demulsify a stable emulsion. The first surfactant is a medium HLB (9 - 14) surfactant molecule which should be preferably two hydrophobic - tailed surfactants and a preferably ionic / non- ionic head group, (n shaped). A second surfactant is a high HLB (preferably HLB > 13) surfactant molecule which should preferably be Single or double tailed ionic / non-ionic surfactant.

[0042] The suitable demulsifiers that are effective at all temperatures above pour point of the emulsion and up to 10°C below the pour point of the emulsion, where below pour point temperatures, high shear mixing may be required before settling.

[0043] They must have following characteristics: a) The demulsifier should be a mixture of Medium HLB surfactant and High HLB surfactant. b) The structure of the medium HLB (9 -14) surfactant molecule should be such that it has two hydrophobic - tails (double tailed) and a preferably ionic / non-ionic head group (preferably T-shaped In shaped), including gemini surfactants, as shown in Fig. 1 c) The high HLB surfactant (preferably HLB > 13) should be Single (or Double) tailed ionic / non-ionic surfactant. d) An anionic, medium HLB (9 -14), oil soluble, double - tailed surfactant (preferably T shapcd / a shaped) can work with an anionic high HLB (phase - inverting) surfactant or a non- ionic, high HLB (phase - inverting) surfactant. However, it will not work in combination with a cationic high HLB (phase - inverting) surfactant because of the formation of salt between cationic and anionic surfactant. e) Similarly, a cationic, medium HLB (9 -14), oil soluble, double tailed surfactant (preferably T shapcd / a shaped) can work with n cationic high HLB (phase - inverting) surfactant or a non-ionic high HLB (phase - inverting) surfactant. However, it will not work in combination with an anionic high HLB (phase - inverting) surfactant because of the formation of salt between cationic and anionic surfactant. f) However, a non-ionic, medium HLB (9 -14), oil soluble, double tailed surfactant (preferably T shapcd / a shaped) can work with either an cationic high HLB (phase - inverting) surfactant or a non- ionic high HLB (phase - inverting) surfactant, or an anionic high HLB (phase - inverting) surfactant.Table 116

[0044] The solution provided by the present invention is novel in terms of selection of demulsifiers that will help in low temperature demulsification in high waxy crude oils, that might be stabilized by asphaltenes or even waxes, hence forming a Pickering emulsion.

[0045] The challenges involved were as follows. Since this was a novel work, we did not have much prior basis on which demulsifiers might be effective for very high-water cuts, at such low temperatures and at a very high rate of separation. Tests were conducted on 100’s of surfactants and their combinations thereof, to be able to determine their efficacy.

[0046] The crude oil used for testing had the following characteristics:

[0047] Crude oil emulsion 1 (Heera Crude oil, ONGC): 18% waxes (weight %), asphaltenes 0.5-0.7% (weight %), and resins of 17 -21 % (weight %). The emulsion comprises

[0048] ~ 60% water by volume. The pour point of the crude oil is 36°C.

[0049] Crude oil emulsion 2: The crude comprises of 30 % waxes (weight %) , <0.1 % asphaltenes(weight %) , and 18 % resins (weight %). The emulsion comprises ~ 60 % water by volume. The pour point of the crude oil emulsion is 56°C.

[0050] They will thereafter be referred to as Crude 1 and crude 2 respectively.

[0051] Tests were carried out in the oil field with the following combination of surfactants: SodiumDodecyl Sulfate + Dioctyl sulfosuccinate sodium salt. These surfactants gave effective demulsification ( ~ > 95% separation) within 5 minutes.Elaborate examples of Successful combinations:A. The protocol for conducting bottle tests using hand shaking in the laboratory is as follows: a) Crude oil emulsion is taken in a lOOmL vial. b) The demulsifier is added to the crude oil at room temperature (~28°C). The vial is then placed in a 45°C water bath for 10 minutes, where it gains flowability. c) The vial is then shaken for 100 times at 45° from the horizontal axis at a rate such that the entire shaking occurs in approximately 90 seconds. d) The vial is then placed back in the water bath at 45°C.The de -emulsification kinetics is observed for 15 minutes. e) The efficiency of demulsification is calculated by the below mentioned equation:(V) / (Vo) X 100 where Vo - Total water content in emulsionV - Volume of water separated after addition of demulsifier f) If the demulsification efficiency is > 90% within the observed 15 minutes, and the water content in the separated oil layer is < 1%, which is analysed using Karl Fischer, then the demulsifier is qualified.B. The protocol for conducting bottle tests using homogenization in the laboratory is as follows: a) Crude oil emulsion is taken in a lOOmL vial. b) The demulsifier is added to the crude oil at room temperature (~28 °C). The vial is then placed in a 45°C water bath for 10 minutes, where it gains flowability.22c) The crude oil is then homogenized at 10,000 rpm (unless specified otherwise) using IKA homogenizer for 10 minutes at 45 °C. d) The efficiency of demulsification is calculated by the below mentioned equation:(V) / (Vo ) X 100 where Vo - Total water content in emulsionV - Volume of water separated after addition of demulsifierExample 1: Combination of Anionic surfactant (double tailed) and anionic surfactant (phase inverting)Chemicals used:1. Dioctyl sulfosuccinate sodium salt - BioXtra, >99% , (obtained from Merck Specialities Pvt. Ltd.)2. Sodium Dodecyl Sulfate - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test with Hand Shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 250 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 100 ppmSeparation rate: Instant -100% separation; ii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol (at 10,000 rpm) : (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 100 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 0 ppmSeparation rate: 15 min - 100% separation; iii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol (at 10,000 rpm) :(Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 0 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 200 ppmSeparation rate: Instant - 100% separation. iv. Crude oil emulsion 1: Using Bottle test with Homogenization Protocol (at 10,000 rpm): For the weakest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 50 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 20 ppmSeparation rate: Instant - 100% separation.23v. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol: For the toughest emulsion available on ONGC Heera Platform (Temperature = 33oC, i.e. less than Pour point temperature) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 300 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 100 ppmSeparation rate: 10 min - 100% separation (for homogenization speed of 5000 rpm) 6 min - 100% separation (for homogenization speed of 10000 rpm) vi. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol: For the toughest emulsion available on ONGC Heera Platform (Temperature = 26oC, i.e. IOOC less than Pour point temperature) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 300 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 100 ppmSeparation rate: 10 min - 100% separation (for homogenization speed of 15000 rpm) vii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol (at 15,000 rpm) For the toughest emulsion available on ONGC Heera Platform : (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 30 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 10 ppmSeparation rate: 15 min - 100% separation; viii. Crude oil emulsion 1: Using Bottle test with Homogenization Protocol (at 15,000 rpm) : For the weakest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 20 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 5 ppmSeparation rate: 5 min -100% separation ; ix. Crude oil emulsion 2 (Wax content = 30wt%): Using Bottle test with Hand Shaking Protocol (Temperature = 57oC, i.e. loC above Pour point temperature): a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 500 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 200 ppmSeparation rate: 10 min -100% separation;Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of AOT : 1g of AOT was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Sodium Dodecyl Sulfate : 1g of SDS was mixed with 100 mL milli q water .Example 2: Combination of Anionic surfactant ( double tailed ) and anionic surfactant (phase inverting).Chemicals used:241. Sodium Bis-(2-ethylhexyl) phosphate (prepared by neutralization reaction between Bis(2 -ethylhexyl) phosphate and excess sodium hydroxide)2. Sodium Dodecyl Sulfate - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate(dissolved in o -xylene) - 250 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 100 ppmSeparation rate: Instant -100% separation ; ii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol :(Temperature > = 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate (dissolved in o -xylene) - 100 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 0 ppmSeparation rate: 15 min -100% separation; iii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol : (Temperature > = 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate (dissolved in o -xylene) - 0 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 200 ppmSeparation rate: Instant -100% separation ; iv. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the weakest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate (dissolved in o -xylene) - 50 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 20 ppmSeparation rate: Instant -100% separation ;Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Sodium Bis-(2-ethylhexyl) phosphate : 1g of Sodium Bis-(2- ethylhexyl) phosphate was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Sodium Dodecyl Sulfate : 1g of SDS was mixed with 100 mL milli q water.Example 3: Combination of Anionic surfactant (double tailed) and non-ionic surfactant (phase inverting)Chemicals used:1. Dioctyl sulfosuccinate sodium salt - BioXtra, >99% , (obtained from Merck Specialities Pvt. Ltd.)2. Tween 80 - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water254. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 250 ppm b. Tween 80 (dissolved in water) - 100 ppmSeparation rate: 1 min -100% separation ; ii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol : (Temperature >= 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 100 ppm b. Tween 80 (dissolved in water) - 0 ppmSeparation rate: Instant -100% separation ; iii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol : (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 0 ppm b. Tween 80 (dissolved in water) - 200 ppmSeparation rate: Instant -100% separation ; iv. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the weakest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 50 ppm b. Tween 80 (dissolved in water) - 20 ppmSeparation rate: Instant -100% separation ;Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of AOT : 1g of AOT was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Tween 80 : 1g of Tween 80 was mixed with 100 mL milli q water .Example 4. Combination of Anionic surfactant (double tailed) and non-ionic surfactant (phase inverting)Chemicals used:1. Sodium Bis-(2-ethylhexyl) phosphate (prepared by neutralization reaction between Bis(2 -ethylhexyl) phosphate and excess sodium hydroxide)2. Tween 80 - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result:26i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate (dissolved in o -xylene) - 250 ppm b. Tween 80 (dissolved in water) - 100 ppmSeparation rate: 5 min -100% separation; ii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol: (Temperature >= 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate (dissolved in o -xylene) - 50 ppm b. Tween 80 (dissolved in water) - 0 ppmSeparation rate: Instant -100% separation ; iii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol : (Temperature> = 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate (dissolved in o -xylene) - 0 ppm b. Tween 80 (dissolved in water) - 200 ppmSeparation rate: Instant - 100% separation; iv. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol: For the weakest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Sodium Bis-(2-ethylhexyl) phosphate (dissolved in o -xylene) - 50 ppm b. Tween 80 (dissolved in water) - 20 ppmSeparation rate: Instant - 100% separation;Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Sodium Bis-(2-ethylhexyl) phosphate : 1g of Sodium Bis-(2- ethylhexyl) phosphate was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Tween 80 : 1g of Tween 80 was mixed with 100 mL milli q water .Example 5. Combination of non-ionic (double tailed) and anionic surfactants (phase inverting) surfactantChemicals used:3. Tergitol - 15-S-5 - (obtained from Merck Specialities Pvt. Ltd.)4. Sodium Dodecyl Sulfate - (obtained from Merck Specialities Pvt. Ltd.)5. Milliq water6. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Tergitol - 15-S-5 (dissolved in o-xylene) - 1000 ppm27b. Sodium Dodecyl Sulfate (dissolved in water) - 300 ppmSeparation rate: 5 min -100% separation ; ii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol: For the toughest emulsion available on ONGC Heera Platform (Temperature = 33oC, i.e. less than Pour point temperature) a. Tergitol - 15-S-5 (dissolved in o -xylene) - 1000 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 300 ppmSeparation rate: 10 min - 100% separation (10,000 rpm homogenization)Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-5 : 1g of Tergitol - 15-S-5 was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Sodium Dodecyl Sulfate : 1g of Sodium Dodecyl Sulfate was mixed with 100 mL milli q water .Example 6. Combination of non-ionic surfactant (double tailed) and anionic surfactants (phase inverting)Chemicals used:1. Tergitol - 15-S-9 (obtained from Merck Specialities Pvt. Ltd.)2. Sodium Dodecyl Sulfate - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Tergitol - 15-S-9 (dissolved in water) - 500 ppm b. Sodium Dodecyl Sulfate (dissolved in water) - 300 ppmSeparation rate: 100% separation within 15 minSolutions of demulsifiers were prepared in the following manner:3. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-9 : 1g of Tergitol - 15-S-9 was mixed with 100 mL o- xylene.4. 10,000 ppm Demulsifier Stock Solution of Sodium Dodecyl Sulfate : 1g of Sodium Dodecyl Sulfate was mixed with 100 mL milli q water .Example 7. Combination of anionic surfactant (double tailed) and non-ionic surfactants (phase inverting)Chemicals used:281. Dioctyl sulfosuccinate sodium salt - BioXtra, > 99% , (obtained from Merck Specialities Pvt. Ltd.)2. Tergitol - 15-S-9 - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result :Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a) Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 250 ppm b) Tergitol - 15-S-9 (dissolved in water) - 175 ppmSeparation rate: 100% within 10 minutes ;Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Dioctyl sulfosuccinate sodium salt : 1g of Dioctyl sulfosuccinate sodium salt was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-9 : 1g of Tergitol - 15-S-9 was mixed with 100 mL milli q water .Example 8. Combination of non-ionic surfactant (double tailed) and non-ionic surfactant (phase inverting)Chemicals used:1. Tergitol - 15-S-5 - (obtained from Merck Specialities Pvt. Ltd.)2. Tween 80 - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result:Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a) Tergitol - 15-S-5 (dissolved in o-xylene) - 1000 ppm b) Tween 80 (dissolved in water) - 1667 ppmSeparation rate: 100% separation within 15 minutes;Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-5 : 1g of Tergitol - 15-S-5 was mixed with 100 mL o- xylene.292. 10,000 ppm Demulsifier Stock Solution of Tween 80 : 1g of Tween 80 was mixed with 100 mL milli q water .Example 9. Combination of non-ionic surfactant (double tailed) and cationic surfactant (phase inverting)Chemicals used:1. Tergitol - 15-S-5 - (obtained from Merck Specialities Pvt. Ltd.)2. CTAB (Cetyl triammonium bromide) - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result:Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a) Tergitol - 15-S-5 (dissolved in o-xylene) - 1000 ppm b) Cetyl triammonium bromide (dissolved in water) - 500 ppmSeparation rate: 100% separation within 15 minutes;Solutions of demulsifiers were prepared in the following manner:10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-5 : 1g of Tergitol - 15-S-5 was mixed with 100 mL o- xylene.10,000 ppm Demulsifier Stock Solution of Cetyl triammonium bromide : 1g of Cetyl triammonium bromide was mixed with 100 mL milli q water .Example 10. Combination of non-ionic surfactant (double tailed) and non- ionic (phase inverting) surfactantChemicals used:1. Tergitol - 15-S-5 - (obtained from Merck Specialities Pvt. Ltd.)2. Tergitol - 15-S-40 - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Tergitol - 15-S-5 (dissolved in o-xylene) - 1000 ppm30b. Tergitol - 15-S- 40 (dissolved in water) - 300 ppmSeparation rate: 15 min - 100% separation ; ii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol: For the toughest emulsion available on ONGC Heera Platform (Temperature = 33oC, i.e. less than Pour point temperature) a. Tergitol - 15-S-5 (dissolved in o -xylene) - 1000 ppm b. Tergitol - 15-S- 40 (dissolved in water) - 300 ppmSeparation rate: 15 min - 100% separationSolutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-5 : 1g of Tergitol - 15-S-5 was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-40 : 1g of Tergitol - 15-S-40 was mixed with 100 mL milli q water.Example 11. Combination of anionic surfactant (double tailed) and non-ionic surfactant (phase inverting)Chemicals used:1. Dioctyl sulfosuccinate sodium salt- (obtained from Merck Specialities Pvt. Ltd.)2. Tergitol - 15-S-40 - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol: For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Dioctyl sulfosuccinate sodium salt (dissolved in o-xylene) - 250 ppm b. Tergitol - 15-S-40 (dissolved in water) - 100 ppm Separation rate: 100% separation within 5 minutes ; ii. Crude oil emulsion 1: Using Bottle Test with Homogenization Protocol: For the toughest emulsion available on ONGC Heera Platform (Temperature = 33oC, i.e. less than Pour point temperature) a. Dioctyl sulfosuccinate sodium salt (dissolved in o -xylene) - 250 ppm b. Tergitol - 15-S- 40 (dissolved in water) - 100 ppmSeparation rate: 5 min - 100% separation (for homogenization at 10,000 rpm) 10 min - 100% separation (for homogenization at 5,000 rpm)Solutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Dioctyl sulfosuccinate sodium salt : 1g of Dioctyl sulfosuccinate sodium salt was mixed with 100 mL o- xylene.312. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-40 : 1g of Tergitol - 15-S- 40 was mixed with 100 mL milli q water .Example 12. Combination of non-ionic surfactant (double tailed) and non-ionic surfactants (phase inverting)Chemicals used:1. Tergitol - 15-S-9 (obtained from Merck Specialities Pvt. Ltd.)2. Tergitol - 15-S-40 - (obtained from Merck Specialities Pvt. Ltd.)3. Milliq water4. O-xylene -98% For Synthesis (obtained from Loba Chemie Pvt. Ltd.)The solution of the surfactants can be made either in o-xylene, water or similar solvents. The solvent used does not determine the efficiency of separation.Result: i. Crude oil emulsion 1: Using Bottle test Hand shaking Protocol : For the toughest emulsion available on ONGC Heera Platform (Temperature > = 37oC) a. Tergitol - 15-S-9 (dissolved in water) - 1000 ppm b. Tergitol - 15-S-40 (dissolved in water) - 300 ppmSeparation rate: 100% separation within 15 minSolutions of demulsifiers were prepared in the following manner:1. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-9 : 1g of Tergitol - 15-S-9 was mixed with 100 mL o- xylene.2. 10,000 ppm Demulsifier Stock Solution of Tergitol - 15-S-40 : 1g of Tergitol - 15-S-40 was mixed with 100 mL milli q water .

[0052] It was also found that an emulsion prepared by mixing the two demulsifiers in the ratio of their effective concentrations, in their respective solvents; as in medium HLB - oil soluble surfactant in the oil phase and high HLB - water soluble surfactant in the water phase, was also effective. The oil phase and the water phase along with the medium HLB surfactant and the high HLB surfactant when homogenized at very high shear rates would form stable emulsions, which effectively demulsify the crude oil emuslion at the above mentioned rates.

[0053] Numerous modifications and adaptations of the system of the present invention will be apparent to those skilled in the art and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the true spirit and scope of this invention.

[0054] The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents, rather than by the foregoing description. All additions, deletions and modifications to the invention as disclosed herein which fall within the meaning and scope of the claims are to be embraced thereby.32

Claims

LAIMSWe Claim:

1. A demulsifier composition for low temperature demulsification of a waxy crude oil emulsion, the composition comprising of: a combination of two chemical surfactants, wherein a first surfactant is a medium HLB (9-14) surfactant molecule, and a second surfactant is a high HLB (HLB > 13) surfactant molecule; wherein the composition is effective at all temperatures ranging from temperatures above the pour point of the emulsion to 10°C below the pour point of the emulsion.

2. The demulsifier composition as claimed in claim 1, the composition can demulsify crude oil with a high wax content ranging from 5 % w / w to 45% w / w.

3. The demulsifier composition as claimed in claim 1, the composition can separate water from the emulsion at temperatures upto 10°C below the pour point of the emulsion.

4. The demulsifier composition as claimed in claim 1, wherein the medium HLB surfactant molecule has two hydrophobic - tails (T-shaped / TI shaped) and a ionic / non-ionic head group.

5. The demulsifier composition as claimed in claim 1, wherein the concentration of the medium HLB surfactant is 20 ppm - 1000 ppm.

6. The demulsifier composition as claimed in claim 1, wherein the high HLB surfactant should be preferably single tailed ionic or non-ionic surfactant.

7. The demulsifier composition as claimed in claim 1, wherein the concentration of the high HLB surfactant is 5 ppm to 500 ppm.

8. The demulsifier composition as claimed in claim 1, wherein the anionic medium HLB, oil soluble (T shaped / 7t shaped) surfactant work with an anionic or a non-ionic high HLB, phase - inverting surfactant.

9. The demulsifier composition as claimed in claim 1, wherein the cationic medium HLB, oil soluble (T shaped / 7t shaped) surfactant works with a cationic or a non-ionic high HLB, phase inverting surfactant.3310. The demulsifier composition as claimed in claim 1, wherein the non-ionic medium HLB, oil soluble (T shaped / 7t shaped) surfactant works with a cationic or anionic or non-ionic phase inverting surfactant.

11. The demulsifier composition as claimed in claim 1, wherein the medium HLB - oil soluble surfactant and the high HLB - water soluble surfactant are effective when dosed either separately or combined together in the form of an emulsion.34

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