NO162566B - PROCEDURE FOR DEMOLUTION OF EMULSIONS - Google Patents

Description

The present invention relates to a method for breaking down water-in-oil petroleum emulsions.

One of the main uses for the present mixture is the breakdown of petroleum emulsions, which enables the separation of these into two main phases. Much of the crude petroleum oil produced in the world is accompanied by some water or brine originating from or adjacent to the geological formations from which the oil is produced. The amount of aqueous phase accompanying the oil can vary from traces to a very large percentage of the total liquid flow. As a result of the natural presence of oil-soluble or dispersible emulsifiers in petroleum, much of the aqueous phase formed in the oil will be emulsified in it, forming stable water-in-oil emulsions.

The literature contains numerous references to such emulsions, the problems caused by them, as well as methods used to break down the emulsions and separate a salable petroleum. See, for example, "The Technology of Resolving Petroleum Emulsions" by L.T. Monson and R.W. Stenzel, pp. 535 etc. in Colloid Chemistry Vol VI, Ed. by Jerome Alexander, Rheinhold Publishing Corp., New York (1946) and "Interfacial Films Affecting the Stability of Petroleum Emulsions" by Chas. M. Blair, Jr, in Chemistry and Industry

>( London) , pp. 538 etc. (1960).

Previously known demulsifiers used to break petroleum emulsions were water-soluble soaps, "Twitchell reagents" and sulfonated glycerides. These products could be easily mixed with water to provide easily pumpable fluids which were conveniently used by pumping into the flow lines at the wellhead or washed down the well casing with water to mix with the well fluids prior to their upflow to the surface. However, these products are only effective in relatively high concentrations and their use contributes significantly to production costs.

Some time ago it was found that certain lightly sulfonated oils, acetylated castor oils and various polyesters, all of which are insoluble in water but soluble in alcohols and aromatic hydrocarbons, were more effective in breaking emulsions. Consequently, essentially the commercial development of demulsifiers has led to the production of agents which are insoluble in both water and petroleum oils and which have other properties which will be described below/ causing them to spread at oil-water interfaces to give very thin , moving films that replace any emulsifier present in the oil, and enable the coalescence of dispersed water droplets. In general, such surface-active agents will hereinafter be referred to as "thin film spreading agents" or "TFSA".

Previously, these compounds had to be composed with and dissolved

in alcohols or highly aromatic hydrocarbon solvents to give readily usable liquid mixtures. A wide spectrum of such mixtures is necessary to treat the many different emulsions that can be found around the world.

Although the current TFSA mixtures are very effective and are possibly up to 50-100 times more effective per volume unit than the original water-soluble demulsifiers, so

they are subject to certain practical disadvantages due to their solubility properties. For example, alcohols and aromatic hydrocarbons which are necessary for the production of a liquid, pumpable mixture/are quite expensive and whose price is close to that of the active demulsifier itself. Furthermore, such solvents are flammable and thus create safety problems and cause greater costs for transport, storage and use. The low flash point can

is improved by the use of high-boiling aromatic solvents, but these are increasingly rare, expensive, and not harmless due to their carcinogenic and dermatological effects.

Furthermore, the existing demulsifiers generally cannot be used in an underground oil or gas well, injection well or the like as they cannot be washed down with either water (or brine) or part of the produced oil, and as they are viscous liquids which only are required in very small quantities, they cannot be safely continuously emitted several thousand meters underground at the liquid level in a typical well without the use of complicated and expensive equipment.

Other applications of TFSA compositions would be facilitated if they were readily soluble or dispersible in water. For example, large quantities of heavy, viscous oil are produced in the USA. using steam injection methods. Typically, wet-steam is injected into the oil-producing strata for several weeks to heat the oil, lower its viscosity and increase the energy of the reservoir. The steam injection is then stopped and the oil flows or is pumped out from the borehole that was used for the steam injection joe. Much of the water that forms as a result of condensation of the steam is also carried with the oil in emulsified form. As emulsions are more viscous than the external phase at the same temperature, the flow resistance will increase and the productivity of "steamed" wells can be improved by injecting a water-soluble demulsifying agent into the steam during the steam injection period to prevent emulsion formation, as indicated in US Patent No. 3,396,792.

The requirement for water solubility will significantly limit the choice of demulsifiers for use by steam or water injection to relatively ineffective mixtures.

As shown in the Norwegian patent applications No. 80.1661, 80.1662, 80.1663 and 80.1664, TFSA are useful when used in the extraction of petroleum. Used in such processes involving the displacement of residual oil by means of aqueous solutions, polymer solutions or other aqueous systems, these compounds will act to increase the amount of recovered oil. Such an effect is possibly due to their ability to promote further water wetting of the reservoir rock, lower the viscosity of the oil-water interface layer and promote coalescence of dispersed droplets of either water or oil in the second phase.

By using the present aqueous micellar solutions, the introduction of TFSA into aqueous displacement or flow fluids can be facilitated to a significant extent. In addition, present micellar solutions as such or in combination with other components will only be used as a flocculating agent or as a pre-treatment agent that is introduced before other aqueous fluids.

Other uses for the present TFSA micellar solutions include their use as flocculation aids for finely ground hematite and magnetite ores during the de-sliming step or ore processing, as additives to improve oil removal and to promote detergency in cleaning compositions and in detergents for use on polar materials, to improve solvent extraction processes such as those used in the extraction of antibiotics where an aqueous fermentation liquid is extracted with organic solvents, to improve efficiency and phase separation in the purification and concentration of metals by solvent extraction with organic solutions of metal complexing agents, as well as to improve wetting and dyeing of natural and synthetic fibers and for other processes that normally involve interfaces between surfaces with different polarity or wetting properties.

One purpose of the present invention is to provide usable aqueous, liquid mixtures of these TFSAs with new and useful properties which enable the production of: petroleum emulsion breakers and emulsion preventing mixtures which are free or relatively free of highly flammable and environmentally harmful aromatic hydrocarbons, mixtures which are relatively cheap, mixtures which are soluble or dispersible in water and which can therefore often be used using more efficient methods than are possible for existing products, mixtures which can be used in enhanced recovery operations such as flotation and flooding with an aqueous medium in which the currently existing products cannot be easily used, as well as mixtures that can be mixed with water-soluble agents of other types, such as corrosion inhibitors, wetting agents, scaling inhibitors, biocides, acid, etc. to provide multi-purpose compounds for use in the solution of many oil well completion ngers, production, transport and refining problems.

According to the present invention, these purposes are achieved by means of amphipathic agents which are capable of forming micelle solutions and which by this mechanism or another

. not well-defined effect, combined with those of the other essential component which will be referred to as a hydrotropic agent, is able to form homogeneous aqueous solutions containing TFSA in a relatively wide concentration range. The TFSA mixtures used according to the present invention can be briefly described using the following general properties: 1. Solubility in water and isooctane at approx. 25° C is less than approx. 1 percent by volume; 2. Solubility parameter at 25° C lies in the range from approx. 6.8 to approx. 8.5 with the main component in the range between 7 and 7.9, and 3. Spreads at the interface between a clear refined mineral oil and distilled water to give a film of a calculated thickness not exceeding approx. 20 Angstroms at a dispersion pressure of approx. 16 dyne/cm.

TFSA mixtures with these properties are generally organic polymers or semi-polymers with molecular weights from approx. 2,000 to approx. 100,000 and have a structure containing a number of distributed hydrophilic and hydrophobic groups arranged in linear or planar rows, which makes them surface-active and causes them to be absorbed at oil-water interfaces under

formation of very thin films.

In contrast to most known surface-active compounds, the present TFSA does not seem to be able to form a micelle in either oil or water. The distributed and alternating presence of polar and non-polar or hydrophilic or hydrophobic groups in the molecule apparently prevents the degree of organization necessary for micelle formation and thus reduces dispersion or dissolution either in water or low polar organic solvents.

TFSAs useful in the present invention have the previously stated properties: 1. Solubility in water and in isooctane at approx. 25° C is less than approx. 1 percent by volume.

Solubility determinations can be carried out by introducing 1 ml of sample (or weight of the solid product calculated to have a volume of 1 ml) into a measuring cylinder of the type that can be closed with a towed glass stopper. Then 99 ml of water is introduced into the cylinder and this is introduced into a water bath at 25° C until temperature equilibrium is reached, after which the measuring cylinder is removed from the bath and shaken vigorously for 1 min. The cylinder is then returned to the bath for 5 min. after which the shaking procedure is repeated, finally the cylinder is returned to the bath and allowed to stand quietly for 1 hour the contents of the cylinder are then carefully examined for any milkiness or opacity of the liquid phase or the presence of any sediment or undissolved material in the cylinder, which indicates that the sample meets the requirements for insolubility in water.

Insolubility in isooctane is similarly determined by using this hydrocarbon rather than water. 2. Solubility parameter (S.P.) at approx. 25° C is in the range 6.9 - 8.5.

Methods for determining the solubility parameter are shown in Joel H. Hildebrand, "The Solubility of Nonelectrolytes", third edition, page 425 etc. However, a simplified method can be used which is sufficiently accurate for the identification of a useful TFSA mixture. Components with a given solubility parameter are generally insoluble in hydrocarbon (non-hydrogen-binding) solvents that have a lower solubility parameter than the actual TFSA mixture. Therefore, the present mixture will be insoluble in a hydrocarbon solvent with a solubility parameter of approx. 6.8. As the solubility parameter for mixtures of solvents is an additive function of the volume percentage of the components in the mixture, sample solutions with the desired solubility parameter can be easily prepared by, for example, mixing benzene (S.P. 9.15) and isooctane (S.P. 6.85) or perfluorine -n-heptane (M.P. 5.7).

A mixture of approx. 7 2 divides benzene by approx. 28 parts of isooctane will provide a solvent with a solubility parameter of approx. 8.5 at room temperature (approx. 25° C). Perfluoro-n-heptane has a solubility parameter of approx. 5.7 at approx. 25° C so that a mixture of 68 parts of this solvent with 32 parts of benzene gives a solvent with a solubility parameter of approx. 6.8 or isooctane with a solubility parameter of 6.85 can be used.

When 5 ml of TFSA is mixed at room temperature with 95 ml of a solvent with a solubility parameter of 8.5, a clear solution should be obtained. When 5 ml of TFSA is mixed with a solvent with a solubility parameter of 6.85, a cloudy mixture or a mixture showing phase separation should be obtained. Solvent mixtures with a solubility parameter between 7.0 and 7.9 can be prepared as described above using

of a corresponding test procedure.

When interpreting the solubility parameter and other determinations, it should be noted that TFSA does not consist of a single material or a single compound, but a cogeneric mixture of products containing a number of products whose molecular weights are distributed around the average molecular weight and which also contain smaller amounts of out- the common compounds used in the production. As a result, when determining solubility and solubility parameters, a slight presence of milkiness or a lack of absolute clarity should not be interpreted as "standing" or "crossed" with respect to satisfying the aforementioned criteria. The purpose of the test is to determine whether the main proportion of the cogeneric mixture, i.e. 75% or more, satisfies the requirements. When the result is doubtful, the solubility tests should be carried out in centrifuge tubes to enable a subsequent rapid phase separation by centrifugation, after which the separated non-solvent phase can be removed and any solvent contained therein can be evaporated and the relevant weight or volume of the separated phase

can be determined.

3. TFSA should spread * ;eg at the interface between distilled water and refined mineral oil to give films with a thickness not exceeding approx. 20 Angstroms (200 nm) at a film pressure of approx. 16 dynes/cm (0.016 Newton/m).

Suitable methods for determining film pressure are shown in N.K. Adam "Physics and Chemistry of Surfaces", Third Edition, Oxford University Press, London, 1941, page 20 etc. and CM. Blair, Jr., "Interfacial Films Affecting The Stability of Petroleum Emulsions", Chemistry and Industry (London), 1960, page 538 etc. The film thickness is calculated on the assumption that all TFSA remains in the interfacial area between oil and water on which the product or a solution thereof in a volatile solvent is applied. As the spreading pressure is numerically equal to the change in the interfacial tension as a result of the film's spreading, you can conveniently perform interfacial tension measurements before and after adding a known amount of TFSA to an interface with a known area.

Alternatively, one can use a boundary film scale of the Langmuir type, such as that described by J.H. Brooks and B.A. Pethica, Transactions of the Faraday Society (1964), page 20 etc. or other methods suitable for the determination of the interfacial spreading pressure.

When determining the interfacial spreading pressure for TFSA products, it is preferred to use a relatively easily available and reproducible oil, such as a clear refined mineral oil, as the oil phase. Such oils are derived from petroleum and are treated with sulfuric acid and other agents to remove non-hydrocarbon and aromatic constituents. Typical of such oils is Nujol (Plough, Inc.).

This oil has a density in the range 0.85 - 0.89 and usually a solubility parameter in the range 6.9 - 7.5. A number of similar oils of greater or lesser density and viscosity are usually available from chemical suppliers and pharmacies.

Other essentially aliphatic or naphthenic hydrocarbons with low volatility are equally suitable and will give similar values for the dispersion pressure. Suitable hydrocarbon oils are commercially available as "white oils", "textile lubricants", "paraffin oil" and the like. These can often contain very small amounts of alpha-tocopherol (vitamin E) or similar oil-soluble antioxidants, but these will not affect the scattering measurements.

Although the existence of micelles, as well as oil or aqueous micelle solutions, has been known for some time, (see for example "Surface Activity", Moilliet, Collie and Black, D.\Van Nostrand & Co., New York (1961)) and probably includes in many operations involving detergents in which either oily

(non-polar) or soil particles (very polar) are to be removed, then their use in collaboration with hydrotropic agents for the present purpose is an unexpected and unforeseeable discovery.

In US patent no. 2,356,205, a number of different micellar solutions are indicated designed to dissolve petroleum oils, bitumen, waxes and other relatively non-polar compounds with the intention of clearing oil formations in order to achieve an improved recovery of petroleum by dissolving it. At this early date, however, application of the micelle principles was not contemplated for the preparation of solutions of relatively high molecular weight demulsifiers.

However, some of the principles set forth in said patent, apart from the main purpose therein of dissolving relatively large amounts of hydrocarbons, chlorinated hydrocarbons and the like, are applicable to the preparation of the present compositions.

The necessary four ingredients for the micelle solutions of TFSA are: 1. A micelle-forming amphipathic agent. Such an agent can be anionic, cationic or non-ionic and if it is anionic or cationic it can either be present in salt form or as the free acid or free base or mixtures thereof. 2. Hydrotropic agent. This is a polar compound of low to medium molecular weight containing oxygen, nitrogen or sulfur and capable of forming hydrogen bonds. It is believed that such agents cooperate in some way with the amphipathic agent to give a clear or opalescent, stable mixture.

3. Water

4. TFSA with the above characteristics.

In addition to these components, the micellar solutions may possibly contain salts, hydrocarbons or smaller amounts of other inorganic or organic material. Such components can be impurities, solvents, or by-products from the production of the hydrotropic agent, or they can be additives that have been found useful in the production of the mixtures according to the invention. As an example of the latter, small amounts of inorganic salts such as NaCl, Na 2 SO 4 , KN0 3 , CaCl 2 and the like may at times be useful in promoting homogeneity with a minimal amount of amphipathic and hydrotropic agents. They can also provide mixtures with a reduced freezing point, a property that is useful when the mixture is to be used in cold climates. In the same way, ethylene glycol, methanol, ethanol, acetic acid and similar organic compounds can be incorporated into the mixtures to improve physical properties such as freezing point, viscosity and density or to improve stability.

As stated above, the micelle-forming amphipathic agents used in the preparation of the present aqueous solutions can either be cationically active, anionically active or of the non-electrolytic type. Amphipathic agents generally have at least one group containing 10 or more carbon atoms and no more than approx. 6 4 carbon atoms per molecule. This is the case for the amphipathic agents used according to the invention as a component of the carrier or the solvent or dispersant used in the present mixtures. The hydrophobic parts of these agents can be aliphatic, alicyclic, alkylalicyclic, aromatic, arylalkyl or alkylaromatic. The preferred type of agents are those where the molecule contains a long unbroken carbon chain containing 10-22 carbon atoms in length. Examples of suitable anion-active amphipathic agents include the usual soaps as well as materials such as sodium cetyl sulfate, ammonium lauryl sulfate, ammonium diisopropyl naphthalene sulfonate, sodium oleyl glyceryl sulfate, brown and green sulfonates from petroleum or petroleum fractions or extracts, sodium stearamidoethyl sulfonate, dodecylbenzene sulfonate, dioctyl sodium sulfosuccinate, sodium naphthenate and the like. Other suitable sulfonates are those shown in US Patent No. 2,278. 171.

Suitable cationic active compounds include cetylpyridine chloride, stearamidoethylpyridine chloride, trimethylheptadecylammonium chloride, dimethylpentadecylsulfonbromide, octadecylamine acetate and 2-heptadecyl-3-diethyleneamino imidazole diacetate.

Suitable non-electrolytic amphipathic agents include oleic esters of nonaethylene glycol, the stearic ester of polyglycerol, oxyethylated alkylphenols and long chain alcohol ethers of polyethylene glycols.

It is of course well known that amphipathic compounds are readily and commercially available or they can be readily prepared to exhibit the properties of one or more of the above-mentioned types. Such compounds are shown in US Patent No. 2,262,743. In cases where a surface-active material can exhibit the properties of one or more of the above-mentioned types, it will be understood that it can be classified under either each or both of the types.

The solvent or the hydrotropic agents in the solution used according to the present invention can be described as compounds of a hydrophobic hydrocarbon residue with a relatively low molecular weight combined with a hydrophilic group with a low molecular weight and which is free of surface-active properties. The hydrophobic residue may contain 2-12 carbon atoms and may be an alkyl group, alicyclic, aromatic or alkyl-substituted alicyclic or aromatic, or may be the hydrocarbon portion of a heterocyclic or hydrocarbon-substituted heterocyclic group. The hydrocarbon residue may be branched or unbranched, but no branch may have a length of more than approx. 7 carbon atoms from the attachment point for the hydrophilic residue, benzene or a cyclohexyl group being considered to have an equivalent length to an aliphatic chain of 3 carbon atoms.

When the hydrocarbon residue consists of no more than 4 carbon atoms, the structure for a normal, primary alkyl group is preferred. When the residue consists of more than 4 carbon atoms, structures of the secondary or tertiary type can also be good if the second and third branches are methyl or ethyl groups.

The hydrophobic hydrocarbon residue is combined either directly or indirectly with a hydrophilic group of one of the following types: (a) A hydroxyl group which may be alcoholic, phenolic or carboxylic; (b) An aldehyde group; (c) A carboxyamide group; (d) An amine salt group;

(e) An amine group; and

(f) An alkali phenolate group.

By "indirectly combined with one of these groups" is meant that the hydrocarbon residue is associated by etherification, esterification, amide formation or the like with other organic residues that do not contain more than four carbon atoms and also one or more of the above-mentioned hydrophilic groups, provided that after each combination, at least one of the hydrophilic groups remains free.

Special examples showing this class of compounds are: Ethyl alcohol, n-amyl alcohol, alphaterpineol, p-cresol, cyclohexanol, n-butyraldehyde, benzaldehyde, n-butyric acid, glycol monobutyrate, propyl lactate, mono-n-butylamine hydrochloride, n-propionamide , ethylene glycol mono-n-butylamine hydrochloride, n-propionamide, ethylene glycol mono-n-butyl ether, pyridine, methylated pyridine, piperidine or methylated piperidines.

The cosolvent (hydrotropic compounds described above) is essentially a semipolar liquid in the sense that any liquid whose polar properties are not greater than that of ethyl alcohol and which exhibits at least a tendency to and dissolve in water or dissolve water is designated as

semipolar.

The co-solvent or the semi-polar liquid as indicated above can be described by the formula X - Z in which X is a group with 2-13 carbon atoms and which can be an alkyl, phenyl, phenylalkyl, cycloalkyl or cycloalkenylalkyl group. There is a limitation, namely that the longest carbon chain must be less than 8 carbon atoms and with such a characterization, cyclic carbon atoms must be counted as half. Z means

-COOH; or -OCH3 where U and V are hydrogen or a hydrocarbon group, means if X is a cyclic tertiary amine group, and is

if X is a cyclic secondary amine group.

The semipolar liquid may also be indicated by the following formula: Rx-NH-CC^n-NH-CC^n-NH-R!, where n=1-5 and R± is hydrogen, alkyl or imidazolinyl.

In general, all of these hydrotropic agents are liquids with a dielectric value of 6-26, and have at least one polar group containing one or more oxygen atoms and/or nitrogen atoms.

It is possibly significant that all these co-solvents are of types known to form hydrogen bonds.

The choice of solubilizer or co-solvent and its proportion in the mixture is to some extent dependent on the amphipathic agent used, the amount and type of TFSA used and the proportion of water used and is best determined by preparing test mixtures on a small scale.

In certain cases, it may be desirable to incorporate small amounts of acid, alkali or inorganic salts into the solution and it has been found that the presence of these electrolytes often gives solutions with greater stability and a wider range of miscibility with water and organic materials. The excess of acid, if used, will usually be in solutions containing a cationically active or non-electrolytic wetting agent. When an excess of alkali is used, this will usually be in a solution containing an anion-active wetting agent.

The resinous polyalkylene oxide adducts or TFSA used according to the invention are generally an organic polymer or semi-polymer with an average molecular weight above approx. 800 and under approx. 30,000 and has a structure that will enable an orientation on polar surfaces with most or all of the molecule's elements in a thin plane. In order to be effectively adsorbed at oil-water or oil-rock interfaces, and then desorbed at water-rock interfaces, the TFSA must generally contain constituents that give it widely distributed hydrophilic and hydrophobic properties and without such a concentration of either hydrophilic or hydrophobic groups as to provide water solubility or oil solubility in the usual macroscopic sense. TFSA seems too

to differ from previously used surfactants in that the effects on the oil-water interfacial tensions as a function of concentration are limited.

During spreading on such interfaces to give thin films with a spreading pressure of up to 35-40 dyne/cm, further larger amounts of TFSA will have relatively little effect on the interface tension. TFSA forms a component of the micellar solution in contrast to previously used surfactants and has little or no tendency to stabilize either oil-in-water or water-in-oil emulsions when present in normally used amounts.

Generally, the TFSA components that are usable in the practice of the present invention are made up of organic molecules containing carbon, hydrogen and oxygen, although in certain cases they may also contain sulphur, nitrogen, silicon, chlorine, phosphorus and other elements. Small amounts of inorganic materials such as alkalis, acids or salts may be present

in the mixture as neutralizing agents, catalyst residues or otherwise. The critical requirements for the TFSA mixture

is not so much the composition as such but more of a structural or physical nature. They must consist of hydrophilic (polar) groups, usually one capable of forming hydrogen bonds, such as hydroxyl, carbonyl, ester, ether, sulfone, amino, ammonium, phosphorus or similar hydrogen-bonding groups attached with or to hydrophobic groups such as alkylene-, alkyl-, cycloalkyl-, aryl-, arylene-, aralkyl-, polyalkylene-, polyalkylene-, combinations of such groups and such groups containing relatively non-polar substituents such as hydrocarbon, chlorine, fluorine and the like. Sometimes the hydrophobic groups are larger and contain more atoms than the polar groups in the molecule and have at least two carbon atoms in each group and up to as many as 36 carbon atoms, although the actual ratio between the sizes is largely dependent on the structure of the hydrophilic unit. Typically, the hydrophobic groups will contain 14-22 carbon atoms and will have linear or sheet-like conformations that allow a relatively flat orientation on surfaces.

Polar units other than the hydrogen bond positions are not excluded from these mixtures, and in fact may be intentionally included in certain structures to improve adsorption and the tendency to spread in interfaces. For example, quaternary ammonium groups, which are unable to form hydrogen bonds, can improve the dispersion and interfacial adsorption in certain applications as a result of their highly ionized form, which imparts a cationic character to - molecules in which they are present and via coulombic repulsion effects improve dispersion in a film.

Generally, the TFSA components will contain at least two of each

of the necessary hydrophilic (polar) and hydrophobic units per molecule and usually they will contain many more of each of these. However, the effective products must exhibit the three characteristics described above.

These compositions are carefully described in US Patent No. 2,499,365. These mixtures also include materials in which less than one or two alkylene oxide units can react with each reactive structural group in the starting resin.

The most common resin is an alkyl or cycloaliphatic substituted phenol-aldehyde resin prepared by condensing an ortho- or para-substituted phenol with an aldehyde, but most commonly . with formaldehyde or a formaldehyde source, such as paraformaldehyde or trioxane, under slightly alkaline or acidic conditions to give a fusible and xylene-soluble polymer of low or moderate molecular weight and which will typically contain from between approx. 4 to approx. 12 phenolic groups. This resin is then condensed, usually with an alkali catalyst, with an alkylene oxide or a mixture of alkylene oxides with 4 or fewer carbon atoms and exemplified by ethylene oxide, propylene oxide, butylene oxide, glyceryl chlorohydrin, epichlorohydrin and glycidoyl.

To be suitable for use in the present process, addition and condensation of oxide must not be carried out to a point where water-soluble products are formed. Where ethylene oxide is condensed alone with the resin, it will amount to between one and five moles per phenol group in the resin. The relevant amount will vary with the size of the alkyl or cycloalkylene group attached to the phenolic ring as well as, apparently, with the composition and properties of the oil, water phase and rock formation which will be relevant in practicing the method.

When propylene or butylene oxides or mixtures of one or more of these with ethylene oxide are condensed with the phenol-resin intermediate, generally a larger amount of such oxides can be reacted without leading to extremely polar, water-soluble products. In contrast, the amount of epichlorohydrin or glycerol chlorohydrin that condenses without forming agents that do not satisfy the solubility and interfacial dispersion conditions, as defined above, may be somewhat lower.

■On a solvent-free weight basis, the amount of the alkylene oxide or mixtures of oxides condensed with the resin will range from approx. 1 part oxide to approx. 10 parts resin and up to from between approx. 1 - 5 and approx. 3-1. The finished product should contain at least approx. 1 mole of alkylene oxide per phenol group in the resin.

Compounds suitable for practicing the present invention are produced by reacting formaldehyde or a compound that breaks down to formaldehyde under the reaction conditions, for example paraformaldehyde and trioxane and a difunctional, with regard to reaction with formaldehyde, alkylphenol which for economic reasons can be a crude mixture of alkylphenols,

and where the reactants are heated to 100° - 125°C in the presence of a small amount of an acidic catalyst, such as sulfamic acid or hydrochloric acid, or optionally in the presence of an alkaline catalyst such as sodium hydroxide or sodium methylate and preferably under essentially anhydrous conditions, except from water formed during the reaction. The aqueous distillate that forms is collected and removed from the reaction mixture. After several hours of heating to temperatures slightly above the boiling point of water, the mass becomes viscous and is allowed to cool to 100 - 105°C. At this point, an aromatic hydrocarbon fraction such as xylene can be added and the heating resumed. Additional aqueous distillates will begin to form, and heating is continued for a further number of hours until approx. 1 mole of aqueous distillate per moles of formaldehyde have distilled off. Xylene or another hydrocarbon that can be distilled with water can be returned to the reaction mass. The temperature at the end of the reaction reaches 180 - 250°C. The product is allowed to cool to give a phenol formaldehyde condensation product in an aromatic solvent.

The molecular weight of these intermediate condensation products cannot easily be established with certainty, but it is assumed that in the resins used these will contain 4-15, preferably 4-6, phenolic groups per resin molecule. The solubility of the condensation product in a hydrocarbon solvent will indicate that the resin is a linear or sheet-like polymer, which distinguishes it from the more common phenol formaldehyde resins of the insoluble cross-linked type.

After the phenol formaldehyde intermediate has been prepared, the next step is oxyalkylation of the condensation products with alkylene oxide. This is achieved by mixing the phenol-formaldehyde condensation intermediate, as is or dissolved in an aromatic solvent, with a small amount of a suitable catalyst, usually potassium hydroxide or sodium methylene in an autoclave. The condensation product heated to over 100°C and ethylene oxide, propylene oxide or mixtures of two or three of these oxides, either as a mixture or a successive addition of one of the oxides, are introduced into the autoclave until a pressure in the range 5-7 kp/cm 2.

The reaction mixture is gradually heated until an exothermic reaction begins. The external heat supply is removed and alkyl oxide or oxide mixture is added in such an amount that the temperature is maintained at 130 - 160°C at a pressure in the range of 2-7 kp/cm 2. After all the alkylene oxide has been added, the temperature is maintained for a further 10-20 min . to ensure essentially complete conversion of the alkylene oxide. The product obtained is the alkylene oxide adduct of an alkylphenol-formaldehyde condensation product in which the weight ratio of oxide to condensation product (calculated on a solvent-free basis) is in the range 1:10 to 10:1, preferably in the range 1:5 to 3:1 and contains at least 1 mole of alkylene oxide per phenol group in the resin.

With regard to the limits of the various constituents i

the micellar solutions containing TFSA, the following can be stated:

Although the exact function of electrolytes previously discussed is not fully understood, the effect can be attributed at least in part to their ability to bind water, i.e. get hydrated. This indicates that certain other materials of a very hydrophilic nature and which clearly differ from the class of non-polar solvents and semi-polar co-solvents can be functional equivalents of an electrolyte. Components in this class that do not usually dissociate include glycerol, ethylene glycol, di-glycerol, sugar, glucose, sorbitol, mannitol and the like.\

As indicated above, these solutions may contain other organic constituents such as hydrocarbons. These are often used as diluents, azeotropic distillation aids or for control of reflux temperatures in the production of the TFSA component and may be back in this when the present micellar solutions are produced. To the extent that such compounds are present, they seem to compete to a certain extent with the TFSA component for micelle space and thus to a certain extent limit the maximum amount of TFSA component that can be brought into a homogeneous solution.

Selection of an effective TFSA mixture for a given petroleum emulsion and determination of the amount that is necessary is carried out by so-called "bottle tests" which are typically carried out in the following way: A fresh emulsion is obtained and 100 ml portions are poured into each of several 180 ml screw-cap precipitation or equivalent graded bottles. Dilute solutions (1% to 2%) of various TFSA ingredients are prepared in isopropyl alcohol. Using a measuring pipette, add a small volume of a TFSA solution to the bottle. A corresponding volume of each of the mixtures is added to the other bottles containing the emulsion. The bottles are then closed and transferred to a water bath and kept at the same temperature as is used at the treatment plant in question. When this temperature is reached, shake the bottles vigorously for several minutes. After shaking, the bottles are placed upright in the water bath and allowed to stand still. At appropriate intervals, the volume of separated water layer is observed together with the sharpness of the oil-water interface, the appearance of the oil and the clarity of the water phase.

After the grace period, which can vary from 30 min. to several hours, depending on the temperature, the viscosity of the emulsion, and the amount of TFSA mixture used, small samples of the oil are removed by means of a pipette or injection syringe, and after the sample they are centrifuged to determine the amount of free and

emulsified water back into the oil.

The pipette or syringe used to remove the samples should be inserted via a cap or other device that acts as a position control to ensure that all bottles are sampled at the same liquid level.

The combined information regarding residual water and emulsion, water separation rate and appearance of the interface forms the basis for choosing the generally most effective TFSA component. If none of the results are satisfactory, the experiments should be carried out using higher concentrations of the TFSA components and, in the opposite case, if all the results are good and equal, the experiments should be carried out at lower concentrations until good differentiation is possible.

When dissolving petroleum emulsions of the water-in-oil type with the present micellar solution, the solution is brought into contact with the emulsion to be treated using one of the various methods or devices that are now generally used to break petroleum emulsions with a chemical agent , the method indicated above being used alone or in combination with other demulsification procedures, such as the electrical dehydration process.

One method is to accumulate a volume of emulsified oil

in a tank and carry out a batch demulsification treatment for

to recover pure oil. In such a method, the emulsion is mixed with the micellar TFSA solution, for example by stirring the emulsion in the tank and slowly dripping the micellar TFSA solution into the emulsion. In certain cases, the mixture can be achieved by heating the emulsion while the micellar TFSA solution is added dropwise, as the convection currents in the emulsion can provide a satisfactory mixture. A third modification of this type of treatment is to extract the emulsion from the bottom of the tank using a circulation pump and reintroduce it to the top of the tank, while the micellar TFSA solution is, for example, supplied by circulation

suction side of the sion pump.

In the second type of treatment, the microcellular TFSA solution is introduced into the well fluids at the wellhead or at a location between the wellhead and the final oil storage tank, using an adjustable metering mechanism or a metering pump. Normally, the liquid flow through the subsequent pipelines and connections will be sufficient to provide the desired mixture of the micellar TFSA solution and emulsion, although in certain cases additional agitation may be introduced into the flow system. In this general method, the system can include various mechanical devices for discharging free water, separating entrained water or treating the chemically treated emulsion in stationary precipitation tanks. Heating devices can be used in connection with the treatment methods described above.

The third way of using the micellar TFSA solution when treating an emulsion is to introduce the micellar solution either intermittently or continuously in diluted form into the well and let it follow the well fluids to the surface and then let the chemical-containing emulsion flow through which .preferably suitable surface equipment as used in other treatment methods. This particular method of application is useful when the micellar solution is used in connection with the acidification of calcareous oil-containing strata, especially if it is dissolved in the acid used in the acidification.

In all cases, it will appear from the given description

that the method generally comprises introducing only a relatively small proportion of a micellar TFSA solution into a relatively large proportion of the emulsion, mixing the added chemical and the emulsion either by natural flow or by means of special devices, with or without the application of heat and then letting the mixture is allowed to stand until the content of unwanted water in the emulsion is separated and settled.

In addition to their use to break petroleum emulsions, the present micellar TFSA solutions, as previously mentioned, can be used to prevent emulsion formation by steam flotation, by secondary water flotation, by acidification of

.oil-producing formations and the like.

Petroleum oils can also contain significant amounts of inorganic salts after demulsification, either in solid form or as small residual brine droplets. For this reason, most petroleum oils will be desalted before refining. The desalination step is carried out by adding and mixing the oil with a few percent by volume of fresh water to bring this into contact with the brine and the salt. In the absence of a demulsifier, such added water will also be emulsified without providing the desired washing effect. The micellar solutions used can be added to the fresh water to prevent it from emulsifying, thus facilitating phase separation and removal of salt during the desalination process. If desired, the solution can be added to the oil phase in the same way as the currently used aromatic solvent mixtures. Most petroleum oils together with accompanying brines and gases have a corrosive effect on steel and other metal structures with which they come into contact. Well pipes, well casings, flow pipelines, separators and storage tanks are often severely attacked by well fluids, especially when acidic gases such as H?S and C02 are present in the fluids, but also in systems that are free of these gases.

It is previously known, for example as stated in US patent no. 2,466,517, that such corrosive attacks of crude oil liquid can be avoided or prevented by adding small amounts of organic inhibitors to the liquids. Effective inhibitor mixtures for such an application are usually semi-polar surfactant compounds containing a non-polar hydrocarbon unit linked to one or more polar groups containing nitrogen, oxygen or sulfur or combinations of these elements. In general, these inhibitors or salts thereof will be soluble in oil and/or water (brine) and will often apparently be able to form micelles in one or both of these phases. Typical inhibitors include amines such as octylamine, dodecylamine, dioctodecylamine, butylnaphthylamine, dicyclohexylamine, benzyldimethyldodecylammonium chloride, hexadecylaminopropylamine, decyloxypropylamine, mixed amines prepared by hydrogenation of nitrile derivatives of tall oil fatty acids, soy acid esters of monoethanolamine, .2-undecyl-1-aminoethylimidazoline and a wide number of cationic nitrogen-containing compounds of a semipolar character.

Active in certain applications are nonylsuccinic acid, diocylnaphthalene sulfonic acid, trimeric and dimeric fatty acids, propargyl alcohol, mercaptobenzothiozole, 2, 4, 6-trimethyl-1, 3, 5-trithiaan, hexadecyldimethylbenzimidazole bromide, 2-thiobutyl-N-tetrodecylpyridine chloride, tetrahydronaphthylthiomorpholine, etc.

In contrast to TFSA, corrosion inhibitors seem to work by forming strongly adherent, thick, densely packed films on the metal surface that prevent or reduce the contact between the corrosive fluids and gases with the metal and affect the ion and electron transfer reactions that are part of the corrosion process.

Corrosion inhibitors are often lowered into the well space in oil wells, where they are mixed with the well fluids before being fed up through the well pipe, and can thus effectively prevent corrosion of the well equipment. When corrosive attack occurs at the surface, the inhibitor can be introduced near or at the wellhead and allowed to adsorb into the pipelines and surface equipment to ensure protection.

Addition of inhibitor, either down the hole or at surface locations, can be suitably combined with the addition of the demulsifier, as the latter is also often added at one of these locations.

Inhibitors such as those mentioned above can generally be incorporated into TFSA micellar solutions and replace part of or in addition to the TFSA component. Furthermore, since many of these inhibitors are themselves micelle-forming amphipathic agents, they can be included in the micellar solution as such and replace other amphipathic agents that might otherwise be used. Combining the micellar solution with corrosion inhibitor enables a more economical chemical treatment and reduces the inventory of a compound, requiring only one chemical injection system instead of two, thus facilitating the work and necessary monitoring.

A further important effect achieved by the use of the micellar solution of TFSA and the corrosion inhibitor is attributed to the prevention of emulsification of the inhibitor. It is often found that the inhibitor, in an amount necessary to achieve an effective protection, causes the formation of very stable emulsions of water and hydrocarbon, especially in systems containing light, normally non-emulsifying hydrocarbons such as distillates such as gasoline, kerosene, diesel oil and various other factions. Inhibitors are commonly used in refining systems where emulsification is highly undesirable and where the mixtures could be reformulated to include an effective emulsion-preventing micellar solution of TFSA.

Inhibitors can be used in an amount from a few to several hundred parts per million, calculated on the oil to be treated and depending on the extent of corrosion. For a given oil field or groups of wells, tests will normally be carried out to determine the requirement for the micellar dissolution of TFSA and for the inhibitor, and a mixture will be prepared containing these components in approximately the desired proportions. In certain cases, the requirements for a micellar solution of TFSA in the best concentration will lead to the use of a corrosion inhibitor, used as a micelle former, in excess of what is necessary for inhibition. This will not affect the applicability of the micellar solution, and will result in an inhibition "surplus" which can be useful during periods when high corrosivity can be expected. Examples of micellar solutions in which TFSA is used with inhibitors in water-dispersible micellar solutions will appear from the following.

Selection of the appropriate corrosion inhibitor for a given system or oil can be based on laboratory testing under conditions similar to those in the well or pipelines. Such tests are exemplified by that described in Item No. 1K155, "Proposed Standardized Laboratory Procedure for Screening Corrosion Inhibitors for Oil and Gas Wells", published by the National Association of Corrosion Engineers, Houston, Texas.

In summary, the method for breaking down a water-in-oil-petroleum emulsion according to the invention can be stated with the features set out in the characterizing part of claim 1.

EXAMPLE 1

Reference is made to US patent no. 2.4 99,365 which generally describes the production of demulsifiers by oxyalkylation of soluble, organic solvents, soluble alkyl-phenolic resins. The method according to Example 7 4a of this patent was followed in the preparation of a fusible, xylene-soluble p-dodecylphenol resin in a xylene solution. The acid catalyst was neutralized and water removed by azeotropic distillation of some xylene and 0.5% by weight sodium methylate catalyst was added. Using example 1b in the aforementioned patent, 25% by weight of ethylene oxide, calculated on the finished batch weight, was added and reacted with the resin. The product obtained satisfied the requirements with regard to solubility, solubility parameter and ability to spread on interfaces. They were also found to be an effective additive to improve oil recovery by waterflooding.

EXAMPLE 2

In a stainless steel reactor with a volume of 7,570 1 and provided with a heating jacket and coils for steam heating and cooling,

a decanter condenser and suitable supply and outlet devices were introduced 1090 kg of a commercially available p-nonylphenol, 545 kg of a high-boiling aromatic solvent and 190 kg of paraformaldehyde flakes. After stirring for approx. 30 min. 4.1 kg of dipropylnaphthalenesulfonic acid was added to the reactor, after which it was closed.

The contents were heated to approx. 40° C at which temperature an exothermic reaction started. The temperature was allowed to rise to 120°C using cooling when necessary to maintain this maximum temperature. The pressure rose to 4.2 kp/cm and the vessel was depressurised when it was necessary to keep the pressure at or below this point. After heating and stirring under these conditions for approx. For 1 hour the temperature was lowered to 95° C and the reactor connected to the reflux decanter system. The temperature was then increased and water was collected in the decanter which was adjusted so that the aromatic solvent flowed back into the reactor while the water was removed from it. The temperature was gradually raised to approx. 230°C and held at this temperature until no more water was given off, after which the finished resin was cooled to 130°C and a further 545 kg of the aromatic solvent was added.

After the resin synthesis was completed, the decanter-condenser system was closed and 18 kg of a 50% solution of potassium hydroxide was slowly added with stirring to the contents of the reactor. A stream of nitrogen was introduced through a pipe which opened at the bottom of the reactor, and was allowed to flow through the contents of this oxygen while the temperature was brought to 110° C. The nitrogen supply was interrupted and the introduction of propylene oxide started. The temperature was allowed to rise to 150° C and was maintained at 140-160° C until 907 kg had been added and reacted. The propylene oxide supply was then closed and ethylene oxide was slowly introduced and allowed to react until a total of 363 kg had been added.

The product is then cooled and pumped to storage. The aromatic solvent was vacuum distilled from a sample of this batch. The product was found to have a solubility parameter of 8.0 and was 1% soluble in water and isooctane. It was found to spread rapidly at the interface between white oil and distilled water with a spreading pressure of 20 dyne/cm 2 and a calculated thickness of 13 Ångstrom and a spreading pressure of 29 dyne/cm at a calculated thickness of

20 Angstroms.

EXAMPLE 3

The procedure of Example 2 was followed, except that 20 kg of a 5% solution of sodium hydroxide in water was used in place of the dipropylnaphthalenesulfonic acid in Example

2. An alkaline catalyzed resin was obtained after removal of water. At this point, 11 kg of sodium methylate was added in place of potassium hydroxide in Example 3, and acted as external catalyst for the subsequent addition of propylene and ethylene oxide. This product was more viscous than that according to Example 2. A purified, solvent-free sample satisfied the three criteria for TFSA as previously

indicated.

EXAMPLES OF MICELLULAR SOLUTIONS OF TFSA

EXAMPLE A

EXAMPLE B

In addition to being a demulsifier for water-in-oil petroleum emulsions, the product exhibited a strong biocidal activity as a result of the biotoxicity of the amphipathic and hydrotropic agents used (respectively dodecyldimethylbenzylammonium chloride and cyclohexanone).

When you want to get rid of the water that is separated from the emulsions by injecting it into an underground formation or where it is to be re-injected for flooding or pressure maintenance in an oil-producing formation, it is very important to prevent biological growth. Such growth causes serious resealing problems and can further lead to sulphide formation and corrosion problems when injected into production wells.

This composition, due to the inclusion of the surface-active quaternary ammonium salt, also contributes to the clarification of the separated water by discharging the natural negative surface charges on the oil droplets and solids that may be dispersed therein during the demulsification and sedimentation steps and thus further improve water quality before its re-injection or removal.

EXAMPLE C

This composition is particularly useful when used downhole where the oil is highly paraffinic and has a high pour point. It contains demulsifier together with an effective wetting agent and solvents to prevent and/or remove waxy or aliphatic deposits that can form in the pipe string and pipelines in the well.

Reference has previously been made to the incorporation of water-insoluble treatment agents such as biocides, scale deposit inhibitors etc. in the present mixtures in order to provide multi-functional compounds for use in oil fields and in refining operations. However, it should be clear that other inherently water-insoluble agents or compounds can also be incorporated into the present mixtures in the form of a micellar solution so that very useful multifunctional mixtures are obtained.

EXAMPLE D

This mixture is an effective demulsifier alone or in combination with other aqueous mixtures of TFSA. It is a particularly effective additive for aqueous flow fluids injected into oil-producing formations to effectively enhance oil recovery. This mixture, when examined by the previously described laboratory procedures, gave the following tabulated results.

Among test methods that have been found useful in selecting the appropriate TFSA is one that involves determining the oil displacement efficiency from treated oil-bearing rock cores in the equipment described below. A tube of glass or transparent polymethacrylate with an inner diameter of approx. 3.5 cm and a length of approx. 45 cm and provided with supply connections and suitable valves at each end. The tube is mounted vertically in a stand in an air bath equipped with a fan, heating elements and a thermostat that allows the selection and maintenance of temperatures in the range 25 - 13 0° C.

In order to select the most effective TFSA for use in a given oil formation, samples of oil, the oil-producing rock formation and the water to be used in the flooding operation are obtained. The rock formation is extracted with toluene to remove oil, dried and then ground in a ball mill to a point where a greater percentage passes a 40 mesh sieve. The fraction between 60 mesh and 100 mesh is retained. The above-described tubes are removed from the air bath, opened and, after introducing a glass wool filter at the lower end, the tube is packed with the painted stone formation. The pipe is gently tapped from time to time during filling to ensure a tight packing and visually inspected to ensure the absence of voids.

The pipe is then returned to the air bath, connected to the supply pipe and the temperature is adjusted to the temperature of the oil formation and oil from such formation is slowly supplied through the bottom supply pipeline from a calibrated reservoir in an amount just sufficient to fill the packed rock plug in the pipe. This volume is determined from the calibrated reservoir and is referred to as "Pore volume" and is the volume of oil that is just sufficient to fill the pores or cavities in the packed rock plug.

The upper pipeline to the reservoir is then connected to a calibrated reservoir containing the oil representing that from the formation to be flowed. By appropriate manipulation of valves, the pipeline can be filled with oil which is then slowly pumped into the core from the reservoir, after which the lower valve is opened to allow displacement of the formation water.

A breakthrough of oil at the bottom is noted, pumping is stopped and the volume of oil introduced into sand is determined from readings from the reservoirs. This is referred to as the volume of oil present. The pipe with the sand containing oil is then placed in the air bath at a temperature corresponding to that of the formation for a period of 3 days to allow equilibrium between the ground formation rock and the oil with regard to adsorption of the oil constituents on the rock and lowering of the interfacial tension. The time for reaching equilibrium can vary within wide limits. At higher temperatures, the time required to achieve equilibrium is probably less. Usually, for comparative tests, 3 days are used to age the oil-stone plug. Results of this procedure approximately simulate working with current cores of oil-bearing rock.

Oil and the water samples used for testing purposes are preferably taken under an inert gas such as pure nitrogen and are kept free from contact with air during all manipulation with the aim of preventing oxidation of the oil and thus the introduction of foreign polar, surface-active components into the oil. At this point, rock systems simulate the original oil formation before primary oil production has begun and the well before a possible secondary waterflow operation.

The other inlet pipe is now connected to the water sample to be used when flooding the oil formation and with the help of an injection syringe or other positive displacement pump with a small displacement, the water is pumped into the sand body from the top to displace liquid out at the bottom of the pipe which is connected to a calibrated receiver . The pump speed is adjusted so as to simulate the speed of the flood water during a current operation, which is usually in the range of 1-50 cm/day. Pumping is maintained at this rate until two pore volumes of water have been pumped through the sand.

The volumes of the liquids collected in the receiver are measured and the relative amount of oil and water displaced from the rock sample determined. mes and recorded. Of particular interest is the volume of oil displaced in relation to the original pore volume. This information can be considered as an indication of the percentage of oil that was originally present and that has been produced by natural expulsion with water after drilling a well in a rock formation followed by the primary production phase carried out to the approximate economic limit.

After this step, a further one to three pore volumes of water containing the TFSA micelle solution to be examined are slowly pumped through the plug, and the further volumes of oil and water displaced are determined. Typically, when such an initial "slug" of micellar TFSA solution is introduced, it can be contained in a liquid volume in the range of 1-100% of the pore volume, but usually this volume will be made up of 10-50% of the pore volume.

After this final displacement step, produced oil and water are again determined. By comparing the amount of oil produced as a result of the further injection of water containing, or after a prior injection of a solution of micellar TFSA solution with an amount produced when the same volume of water is injected without TFSA solution present, then one can calculate the efficiency of the special micellar TFSA solution used to improve the recovery of additional oil compared to that achieved by ordinary waterflooding.

In general, 6 or more sand columns of the described type will be installed in the heated air bath. Examination of a given micellar TFSA solution is carried out "in triplo" using identical conditions and concentrations simultaneously with three blank samples without addition of the micellar TFSA solution to the water.

The mixture according to Example D was examined by this method under the following conditions.

The oil was displaced by pumping two pore volumes of water into the sand. After measuring the volumes of oil and water produced via the bottom pipeline, a further 0.2 pore volumes of water containing 3,500 ppm of the mixture according to Example D were injected followed by 2.8 pore volumes of water containing 200 ppm of the mixture according to Example D. Measurement of the volumes of oil and formed water was read after every 0.2 pore volume of injected water.

The result of this test for the injection of 2,3 and 5 pore volumes of water, respectively, is given in the following table, in which average figures for 3 determinations are reproduced.

Use of the mixture according to example D in the above

for given quantities led to a production of 210% more oil from injection of an additional drilling volume of water than that provided by water injection alone and produced 260% more oil after injection of an additional 3 pore volumes of treated water.

EXAMPLE E

This acidic, homogeneous, aqueous, highly viscous mixture is particularly useful as an emulsification inhibitor in hydrochloric acid-acidic solutions used in the treatment of calcareous oil-bearing strata. It is easily dispersible in 15% hydrochloric acid and mixtures thereof with hydrofluoric acid, and prevents emulsification of the acid and also prevents emulsification of the used acidic solution that will be carried up with produced petroleum. It is also a particularly effective additive for aqueous flooding fluids injected to achieve secondary or tertiary recovery of petroleum, or it can be used alone or diluted with one or two volumes of water to provide improved flow distribution in the flooded zone and to enhance oil recovery.

Claims (2)

1. Process for breaking down water-in-oil-petroleum emulsions, characterized in that it comprises subjecting the emulsion to the action of a micellar solution of a thin-film spreading agent comprising: (1) 5-75% by weight of a polyepoxide concentrate of a poly-alkylene oxide adduct of a fusible, water-insoluble synthetic resin soluble in an aromatic hydrocarbon solvent, which resin contains 4-15 phenolic groups and is an alkyl-substituted phenolaldehyde concentrate of an ortho- or para-substituted phenol and an aldehyde, after which the condensate resin is further condensed with an alkylene oxide containing less than 5 carbon atoms in an amount equal to at least 1 mol of alkylene oxide per phenolic group in the resin, the weight ratio of oxide to condensation product in the solvent-free state being in the range 1:10 to 10:1, and which condensate at 25°C (a) is less than 1% by volume soluble in water and in isooctane, (b) has a solubility parameter in the range of 6.9-8.5, and (c) spreads at the interface between distilled water and refined mineral oil to give a film of thickness not greater than 20 Å at a film pressure of 16 dynes/ cm, (2) 2-30% by weight of a hydrotropic agent of formula in which X is an alkyl, optionally substituted with alkyl phenyl, phenylalkyl, cycloalkyl or cycloalkenylalkyl group with 2-13 carbon atoms, Z is where U and V are hydrogen or hydrocarbon substituents, n = 1-5, is hydrogen, alkyl or imidazolinyl, (3) 2-30% by weight of an amphipathic agent of formula where R~ is alkyl with more than 10 carbon atoms, R3 is SO^X where X is an alkali metal or optionally with alkyl or cycloalkyl substituted ammonium, or R is -0-( (CH0) n -0) m-SO-.X where m and n are 1-10 and X is as above, (4) 15-90% by weight water. 2. Method according to claim 1, characterized in that a hydrotropic agent is used which is a semipolar hydrogen bond-forming compound containing at least one oxygen, nitrogen or sulfur atom and 2-12 carbon atoms.