US 4,326,985 AGrant
Micellar Solutions of Thin Film Spreading Agents Comprising an Acylated Polyether Polyol
Issue Date:1982-04-27
•50 Claims
Abstract
The invention provides a homogeneous, micellar solution of a water-insoluble thin film spreading agent comprising: (a) from between about 5% and about 75% by weight of an acylated polyether polyol; (b) from between about 2% and about 30% by weight of a hydrotropic agent; (c) from between about 2% and about 30% by weight of an amphipathic agent; and (d) from between about 15% and about 90% by weight of water.
Metadata
Assignee
- Magna Corporation
Inventor
- Charles M. Blair, Jr.
Application Information
Application Number:US 0823651
Filing Date:1979-10-05
Priority Date:1979-10-05
Art Unit:223
Classifications
IPC:
B01D 1704
Field of Search:
2521668.55 D;8.55 C;331;333;339;344;358303
Patent Drawings
This patent does not have any drawings.
Description
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The invention relates to a new and improved micellar solution of a thin film spreading agent comprising an acylated polyether polyol which is particularly useful for breaking or preventing petroleum emulsions. More specifically, the invention relates to a composition in which water replaces all or a substantial part of the organic solvents formerly required for preparation of liquid solutions of this interfacially active compound.
2. DESCRIPTION OF THE PRIOR ART
One of the principal uses of the present composition is in the breaking of petroleum emulsions to permit the separation thereof in two bulk phases. Much of the crude petroleum oil produced throughout the world is accompanied by some water or brine which originates in or adjacent to the geological formation from which the oil is produced. The amount of aqueous phase accompanying the oil may vary from a trace to a very large percentage of the total fluid produced. Due to the natural occurrence in most petroleum of oil-soluble or dispersible emulsifying agents, much of the aqueous phase produced with oil is emulsified therein, forming stable water-in-oil emulsions.
The literature contains numerous references to such emulsions, the problems resulting from their occurrence, and the methods employed to break them and separate salable petroleum. See, for example, "The Technology of Resolving Petroleum Emulsions" by L. T. Monson and R. W. Stenzel, p. 535 et seq 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), p. 538 et seq (1960).
Early demulsifiers used to resolve petroleum emulsions were water-soluble soaps, Twitchell reagents, and sulfonated glycerides. These products were readily compounded with water to form easily pumpable liquids and were conveniently applied by pumping into flow lines at the well head or by washing down the casing annulus with water to commingle with well fluids prior to their flow to the surface. These products, however, were effective only at relatively high concentrations and their use added substantially to the cost of production.
Some time ago, it was discovered that certain lightly sulfonated oils, acetylated caster oils and various polyesters, all of which were insoluble in water but soluble in alcohols and aromatic hydrocarbons, were much more effective in breaking emulsions. Accordingly, essentially all commercial demulsifier development has led to production of agents which are insoluble in both water and petroleum oils and have other properties to be described below which cause them to spread at oil-water interfaces to form very thin, mobile films which displace any emulsifying agent present in the oil to allow coalescence of dispersed water droplets. Generally, such interfacially active compounds are hereafter referred to as Thin Film Spreading Agents, or "TFSA's". In the past, these have had to be compounded with and dissolved in alcohols or highly aromatic hydrocarbon solvents in order to produce readily applied liquid compositions. A wide variety of such compositions are required to treat the many different emulsions encountered throughout the world.
While present TFSA compositions are highly effective, being, perhaps, up to fifty to a hundred times more effective per unit volume than the original water-soluble demulsifiers, they suffer serious practical deficiencies because of their solubility characteristics. For example, alcohols and the aromatic hydrocarbons, which are required for preparation of liquid, pumpable compositions, are quite expensive, today approaching in cost that of the active demulsifier ingredient itself. Further, such solvents are flammable and thus create safety problems and entail more expense in shipping, storing and use. The low flash point flammability can be improved by using high boiling aromatic solvents, but these are increasingly rare, expensive and dangerous from the standpoint of carcinogenicity and dermatological effects.
Still further, present demulsifiers cannot generally be used in a subterranean oil or gas well, injection well, or the like, since they cannot be washed down with either water (or brine) or a portion of the produced oil, and, being viscous liquids which are required in very small amounts, they cannot be reliably and continuously delivered several thousand feet down at the fluid level in a typical well without use of elaborate and expensive delivery means.
Other applications of TFSA compositions would be facilitated if they were readily soluble or dispersible in water. For example, much heavy, viscous oil is produced in the United States by steam injection procedures. Typically, wet steam is injected into the oil producing strata for several weeks in order to heat the oil, lower its viscosity and increase reservoir energy. Steam injection is then stopped and oil is flowed or pumped from the bore hole which was used for steam injection. Much of the water resulting from condensation of the steam is also produced with the oil in emulsified form. Since emulsions are more viscous than the external phase at the same temperature, and thus create increased resistance to flow, productivity of the steamed wells can be improved by injecting a water-soluble demulsifier into the wet steam during the steam injection period to prevent emulsion formation. See, for example, U.S. Pat. No. 3,396,792, dated Apr. 1, 1966, to F. D. Muggee. At present, the requirement of water solubility seriously limits the choice of demulsifiers for use in steam or water injection to the relatively inefficient compositions.
As disclosed in my co-pending applications, Ser. No. 045,479, filed June 4, 1979 and entitled "Method Of Recovering Petroleum From A Subterranean Reservoir Incorporating A Polyether Polyol", Ser. No. 45,478, filed June 4, 1979, now U.S. Pat. No. 4,260,019, and entitled "Method of Recovering Petroleum From A Subterranean Reservoir Incorporating Resinous Polyalkylene Oxide Adducts", Ser. No. 45,360, filed June 4, 1979, now U.S. Pat. No. 4,216,828, and entitled "Method Of Recovering Petroleum From A Subterranean Reservoir Incorporating An Acylated Polyether Polyol", and Ser. No. 45,470, filed June 4, 1979, and entitled "Method of Recovering Petroleum From A Subterranean Reservoir Incorporating Polyepoxide Condensates Of Resinous Polyalkylene Oxide Adducts And Polyether Polyols", TFSA's are useful in processes for enhanced recovery of petroleum. Used in such processes involving displacement of residual oil by aqueous solutions, polymer solutions and other aqueous systems, these agents act to increase the amount of oil recovered. Such action possibly arises from their ability to further water wetting of reservoir rock, lessen the viscosity of the oil-water interfacial layer and promote coalescence of dispersed droplets of either water or oil in the other phase.
By use of the present aqueous micellar solutions, the introduction of TFSA into aqueous displacement or flooding fluids is greatly facilitated. In addition, the present micellar solutions, per se, or in combination with other components, can be used as the flooding agent or as a pretreating bank or slug ahead of other aqueous fluids.
Other applications for the present TFSA micellar solutions include their use as flocculation aids for finely ground hermatite and magnetite ores during the desliming step of ore beneficiation, as additives for improving the oil removal and detergent action of cleaning compositions and detergents designed for use on polar materials, for the improvement of solvent extraction processes such as those used in extraction of antibiotic products from aqueous fermentation broths with organic solvents, for the improvment of efficiency and phase separation in the purification and concentration of metals by solvent extraction with organic solutions of metal complex-forming agents, and as assistants to improve the wetting and dying of natural and synthetic fibers and for other processes normally involving the interface between surfaces of differing polarity or wetting characteristics.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide aqueous, liquid compositions of these TFSA's having new and useful characteristics which allow production of: petroleum emulsion breakers and emulsion preventing compositions free or relatively free of highly flammable and environmentally objectionable aromatic hydrocarbons; compositions having a comparatively low cost; compositions which are soluble or dispersible in water and which, therefore, can often be applied by more effective methods than can existing products; compositions which can be used in enhanced recovery operations such as steam flooding and aqueous medium flooding where present products cannot be readily applied; and compositions which can be compounded with watersoluble reagents of other types, such as corrosion inhibitors, wetting agents, scale inhibitors, biocides, acids, etc., to provide multipurpose compounds for use in solving many oil well completion, production, transportation and refining problems.
In accordance with the present invention, these aims are accomplished by means of amphipathic agents which are capable of forming micellar solutions and which by this mechanism or other undefined actions, combined with those of a second essential component which will be referred to as a hydrotropic agent, are able to form homogeneous aqueous solutions containing a relatively wide range of concentrations of TFSA.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The TFSA compositions of the present invention can be broadly categorized by the following general characteristics:
1. Solubility in water and isooctane at about 25.degree. C. is less than about 1% by volume;
2. Solubility parameter at about 25.degree. C. is in the range of from between about 6.8 to about 8.5, with a majority in the range of from between 7.0 and about 7.9; and
3. Spread at the interface between white, refined mineral oil and distilled water to form films having a calculated thickness no greater than about 20 Angstroms at a spreading pressure of about 16 dynes per cm.
TFSA compositions having these properties are generally organic polymers or semi-polymers having molecular weights ranging from about 2,000 to about 100,000 and having structures containing a multiplicity of distributed hydrophilic and hydrophopic moieties arranged in linear or planar arrays which make them surface active and lead to their adsorption at oil-water interfaces to form very thin films.
Unlike most commonly encountered surface-active compounds, the present TFSA appears to be incapable of forming a micelle in either oil or water. The distributed and alternating occurrence of polar and nonpolar or hydrophilic and hydrophobic groups in the molecule apparently prevents the kind of organization required for micelle formation and thus impairs dispersion or solution in either water or low polarity organic solvents.
The TFSA's useful in the present invention have the previously recited properties:
1. The solubility in water and in isooctane at about 25.degree. C. is less than about 1% by volume.
Solubility tests may be run by placing a 1 ml sample (or the weight of solid product calculated to have a volume of 1 ml) in a graduated cylinder of the type which may be closed with a ground glass stopper. Thereafter place 99 ml of water in the cylinder, close, place in a 25.degree. C. water bath until thermal equilibrium is reached, and remove from the bath and shake vigorously for one hour. Return the sample to the bath for five minutes and then repeat the shaking procedure. Finally, return the sample to the bath and allow it to stand quietly for one hour. The cylinder contents should be carefully examined and any cloudiness or opacity of the liquid phase or the appearance of any sediment or undissolved material in the cylinder noted, thus indicating that the sample satisfied the requirement for insolubility in water.
Isooctane solubility is determined similarly by substituting this hydrocarbon for the water used above.
2. The Solubility Parameter (S.P.) at about 25.degree. C. is from between about 6.9 and about 8.5, inclusive.
Methods of determination of solubility parameter are disclosed in Joel H. Hildebrand, "The Solubility of Nonelectrolytes", Third Edition, pgs. 425 et seq. However, a simplified procedure, sufficiently accurate for qualification of a useful TFSA composition may be utilized. Components of a give solubility parameter are generally insoluble in hydrocarbon (non-hydrogen-bonding) solvents having a lower solubility parameter than themselves. Therefore, the present composition should be insoluble in a hydrocarbon solvent of a solubility parameter of about 6.8. Since the solubility parameter of mixtures of solvents is an additive function of volume percentage of components in the mixture, test solutions of the desired solubility parameters may be easily prepared by blending, for example, benzene (S.P. 9.15) and isooctane (S.P. 6.85) or perfluoro-n-heptane (S.P. 5.7).
A mixture of about 72 parts of benzene with about 28 parts of isooctane will provide a solvent having a solubility parameter of about 8.5 at room temperature (about 25.degree. C.). Perfluoro-n-heptane has a solubility parameter of about 5.7 at 25.degree. C., so a mixture of 68 parts of this solvent with 32 parts of benzene provides a solvent with a solubility parameter of about 6.8, or isooctane of a solubility parameter 6.85 may be used.
When 5 ml of the TFSA are mixed with 95 ml of an 8.5 solubility parameter solvent at room temperature, a clear solution should result. When 5 ml of TFSA is mixed with a 6.85 solubility parameter solvent, a cloudy mixture or one showing phase separation should result. Solvent mixtures have a solubility parameter between about 7.0 and about 7.9 may be prepared as described above and utilized in a similar test procedure.
In interpreting the solubility parameter and other tests, it should be recognized that the TFSA consists not of a single material or compound but a cogeneric mixture of products containing a range of products of molecular weights distributed around the average molecular weight and even containing small amounts of the starting compounds employed in the synthesis. As a result, in running solubility and solubility parameter tests, very slight appearances of cloudiness or lack of absolute clarity should not be interpreted as a pass or a failure to pass the criteria. The intent of the test is to ensure that the bulk of the cogeneric mixture, i.e., 75% or more, meets the requirement. When the result is in doubt, the solubility tests may be run in centrifuge tubes allowing subsequent rapid phase separation by centrifuging, after which the separated nonsolvent phase can be removed, any solvent contained in it can be evaporated, and the actual weight or volume of separated phase can be determined.
3. The TFSA should spread at the interface between distilled water and refined mineral oil to form films with thickness no greater than about 20 Angstroms (0.0020 micrometer) at a spreading pressure of about 16 dynes per cm (0.016 Newton per meter).
Suitable methods of determining film pressure are disclosed in N. K. Adam, "Physics and Chemistry of Surfaces", Third Edition, Oxford University Press, London, 1941, pgs. 20 et seq, and C. M. Blair, Jr., "Interfacial Films Affecting The Stability of Petroleum Emulsions", Chemistry and Industry (London), 1960, pgs. 538 et seq. Film thickness is calculated on the assumption that all of the TFSA remains on the area of interface between oil and water on which the product or its solution is a volatile solvent has been placed. Since spreading pressure is numerically equal to the change in interfacial tension resulting from spreading of a film, it is conveniently determined by making interfacial tension measurments before and after adding a known amount of TFSA to an interface of known area.
Alternatively, one may utilize an interfacial film balance of the Langmuir type such as that described by J. H. Brooks and B. A. Pethica, Transactions of the Faraday Society (1964), p. 20 et seq, or other methods which have been qualified for such interfacial spreading pressure determinations.
In determining the interfacial spreading pressure of the TFSA products, I prefer to use as the oil phase a fairly available and reproducible oil such as a clear, refined mineral oil. Such oils are derived from petroleum and have been treated with sulfuric acid and other agents to remove nonhydrocarbon and aromatic constituents. Typical of such oils is "Nujol", distributed by Plough, Inc. This oil ranges in density from about 0.85 to 0.89 and usually has a solubility parameter between about 6.9 and about 7.5. Numerous similar oils of greater or smaller density and viscosity are commonly available from chemical supply houses and pharmacies.
Other essentially aliphatic or naphthenic hydrocarbons of low volatility are equally usable and will yield similar values of spreading pressure. Suitable hydrocarbon oils appear in commercial trade as refined "white oils", "textile lubricants", "paraffin oil", and the like. Frequently, they may contain very small quantities of alpha-tocopherol (Vitamin E) or similar antioxidants which are oil-soluble and do not interfere with the spreading measurements.
While the existence of micelles and of oily or aqueous micellar solutions have been known for some time (see, e.g., "Surface Activity", Moilliet, Collie and Black, D. Van Nostrand & Co., New York (1961)) and are probably involved in many operations involving detergency where either oily (nonpolar) or earthy (highly polar) soil particles are to be removed, their utility in cooperation with hydrotropic agents for the present purposes is an unexpected and unpredictable discovery.
In U.S. Pat. No. 2,356,205, issued Aug. 22, 1944, to Chas. M. Blair, Jr. and Sears Lehman, Jr., a wide variety of micellar solutions designed to dissolve petroleum oils, bitumen, wax, and other relatively nonpolar compounds are described for purposes of cleaning oil formation faces and for effecting enhanced recovery of petroleum by solution thereof. At this early date, however, the use of micellar principles was not contemplated for the preparation of solutions of the relatively high molecular weight demulsifiers.
However, some of the principles disclosed in the above patent, omitting the main objective therein of dissolving relatively large amounts of hydrocarbons, chlorinated hydrocarbons, and the like, are applicable to preparation of the present compositions.
The four necessary components of the micellar solutions of TFSA are:
1. A micelle-forming amphipathic agent. Such may be anionic, cationic, or nonionic and, if anionic or cationic, may be either in salt form or as the free acid or free base or mixtures thereof.
2. A hydrotropic agent. This is a small to medium molecular weight semi-polar compound containing oxygen, nitrogen or sulfur and capable of forming hydrogen bonds. It is believed that such agents cooperate in some manner with the amphipathic agent to form clear or opalescent, stable compositions.
3. Water.
4. TFSA, having the properties recited above.
In addition to these components, the micellar solutions may contain, but are not required to contain, salts, hydrocarbons, or small amounts of other inorganic or organic material. Such constituents may be impurities, solvents, or by-products of syntheses used in forming the hydrotropic agent, or may be additions found useful in forming the composition of this invention. As an example of the latter, small amounts of inorganic salts such as NaCl, Na.sub.2 SO.sub.4, KNO.sub.3, CaCl.sub.2, and the like, are sometimes helpful in promoting homogeneity with a minimum of amphipathic and hydrotropic agents. They may also yield compositions of lower freezing point, a property useful when the composition is employed in cold climates. Similarly, ethylene glycol, methanol, ethanol, acetic acid, or similar organic compounds may be incorporated into the compositions to improve physical properties such as freezing point, viscosity, and density, or to improve stability.
As stated above, the micelle-forming amphipathic agents which may be used in preparing the aqueous solutions herein contemplated may be either cation-active, anion-active, or of the nonelectrolytic type. Amphipathic agents generally have present at least one radical containing about 10 or more carbon atoms and not more than about 64 carbon atoms per molecule. This is true of the amphipathic agents employed in the present invention as a component of the vehicle or solvent or dispersant employed in the present compositions. The hydrophobic portions of these agents may be aliphatic, alicyclic, alkylalicyclic, aromatic, arylalkyl, or alkylaromatic. The preferred type of agents are those in which the molecule contains a long, uninterrupted carbon chain containing from 10 to 22 carbon atoms in length. Examples of suitable anion-active amphipathic agents include the common soaps, as well as materials such as sodium cetyl sulfate, ammonium lauryl sulfonate, ammonium di-isopropyl naphthalene sulfonate, sodium oleyl glyceryl sulfate, mahogany 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 disclosed and taught in U.S. Pat. No. 2,278,171, issued Feb. 17, 1942, to De Groote and Keiser.
Suitable cation-active compounds include cetyl pyridinium chloride, stearamidoethyl pyridinium chloride, trimethyl-heptadecyl ammonium chloride, dimethyl-pentadecyl sulfonium bromide, octadecylamine acetate, and 2-heptadecyl-3-diethylene diaminoimidazoline diacetate.
Suitable nonelectrolytic amphipathic agents include the oleic acid ester of nonaethylene glycol, the steric acid 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 can be readily prepared to exhibit the characteristics of more than one of the above mentioned types. Such compounds are disclosed in U.S. Pat. No. 2,262,743, dated Nov. 11, 1941, to De Groote, Keiser and Blair. For convenience, in such instances where a surface-active material may show the characteristics of more than one of the above described types, it is understood that it may be classified under either or both types.
The mutual solvent or hydrotropic agents of the solution utilized in the present invention are characterizable as compounds of a hydrophobic hydrocarbon residue of comparatively low molecular weight combined with a hydrophilic group of low molecular weight and are free from surface-active properties. The hydrophobic residue may contain from 2 to 12 carbon atoms and may be alkyl, 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 have branched or normal chain structure, but no branch may have a length of more than 7 carbon atoms from the point of attachment to the hydrophilic residue, counting a benzene or cyclohexyl group as being equivalent in length to an aliphatic chain of three carbon atoms. Where the hydrocarbon residue consists of not more than 4 carbon atoms, structures of the normal primary alkyl type are preferred. Where the residue is made up of more than four carbon atoms, then structures of secondary and tertiary types are also good where the second and third branches may be methyl or ethyl groups.
This hydrophobic hydrocarbon residue is combined either directly or indirectly with a hydrophilic group of one of the following groups:
(a) A hydroxyl group which may be alcoholic, phenolic, or carboxylic;
(b) An aldehyde group;
(c) A carboxy amide group;
(d) An amine salt group;
(e) An amine group; and
(f) An alkali phenolate group.
By "indirectedly combined with one these groups" is meant that the hydrocarbon residue is combined as by etherification, esterification, or amidification, or the like, with another organic residue which contains not more than four carbon atoms and also one or more of the hydrophilic groups named above, provided that after said combination, at least one of the hydrophile groups remains free. Specific examples illustrating this class of compounds are: Ethyl alcohol, n-amyl alcohol, alphaterpineol, p-cresol, cyclohexanol, n-butyraldehyde, benzaldehyde, n-butyric acid, glycol mono-butyrate, propyl lactate, mono n-butyl amine hydrochloride, n-propionamid, ethylene glycol mono n-butyl amine hydrochloride, n-propionamid, ethylene glycol mono n-butyl ether, pyridine, methylated pyridine, piperidine, or methylated piperidines.
The solubilizer (mutual solvent or hydrotropic compound above described) is essentially a semi-polar liquid in the sense that any liquid whose polar character is no greater than that of ethyl alcohol and which shows at least some tendency to dissolve in water, or have water dissolved in it, is properly designated as semi-polar.
The solubilizer or semi-polar liquid indicated may be illustrated by the formula X--Z, in which X is a radical having 2 to 12 carbon atoms, and which may be alkyl, alicyclic, aromatic, alkylalicyclic, alkylaryl, arylalkyl, or alicyclicalkyl in nature, and may, furthermore, include heterocyclic compounds and substituted heterocyclic compounds. There is the added limitation that the longest carbon atom chain must be less than eight carbon atoms, and that, in such characterization, cyclic carbon atoms must be counted as one-half. Z represents: ##STR1## where U and V are hydrogen or a hydrocarbon substituent and Me is an alkalie metal; ##STR2## if X is a cyclic teritary amine nucleus;
if X is a cyclic secondary amine nucleus.
The semi-polar liquid also may be indicated by the following formula: X--Y--R--(Z).sub.n. Here X and Z have their previous significance, R is --CH.sub.2 --,--C.sub.2 H.sub.4 --,--C.sub.3 H.sub.5 .dbd.; --C.sub.3 H.sub.6 -- or --C.sub.2 H.sub.4 --O--C.sub.2 H.sub.4 -- and n is either one or two as the choice of R demands. Y is one of the following: ##STR3##
In general, these hydrotropic agents are liquids having dielectric constant values between about 6 and about 26, and have at least one polar group containing one or more atoms of oxygen, and/or nitrogen. It is significant, perhaps, that all of the solubilizers are of types known to be able to form hydrogen bonds.
The choice of solubilizer or common solvent and its proportion in the mixture depends somewhat upon the amphipathic agent used, the amount and kind of TFSA used, and the proportion of water used, and is best determined by preparing experimental mixtures on a small scale.
In some cases, it is desirable to include in the solution small amounts of acid, alkali, or inorganic salts, as it has been found that the presence of these electrolytes often gives solutions having greater stability and a wider range of miscibility with water and organic material. Excess acid, when used, will usually be in solutions containing a cation-active or nonelectrolytic wetting agent, but not exclusively so. Excess alkali, when used, will usually be in a solution containing anion-active wetting agents, but, again, not exclusively.
The acylated polyether polyol or TFSA utilized in this invention is generally an organic polymer or semi-polymer with an average molecular weight above about 800 and below about 30,000 and has a structure which will allow orientation on polar surfaces with much or most of the elements of the molecule in a thin plane. To be effectively adsorbed at oil-water or oil-rock interfaces and subsequently to be desorbed at water-rock interfaces, the TFSA must generally contain constituents which give it a highly distributed hydrophile and hydrophobe character, and without such concentrations of either hydrophilic or hydrophobic groups as to produce water solubility or oil solubility, in the ordinary macroscopic sense. The TFSA also appears to differ from formerly used surfactants in that the effects on oil-water interfacial tensions as a function of concentration are limited. While spreading efficiently at such interfaces to form thin films with spreading pressures up to about 35 to 40 dynes per cm, addition or larger amounts of TFSA have relatively little effect on interfacial tension. Also, the present TFSA constituent of the micellar solution in contrast to formerly used surfactants, has relatively little or no tendency to stabilize either oil-in-water or water-in-oil emulsions when present in normal use amounts.
Usually the TFSA constituents applicable to the practice of the invention are organic molecules containing carbon, hydrogen and oxygen, although in some instances they may also contain sulfur, nitrogen, silicon, chlorine, phosphorous or other elements. Small amounts of inorganic material such as alkalies, acids or salts may appear in the compositions as neutralizing agents, catalyst residues or otherwise. The critical requirements for the TFSA compositions are not so much compositional as structural and physical. They must be made up of hydrophilic (polar) moieties, usually ones capable of forming hydrogen bonds, such as hydroxyl, carbonyl, ester, ether, sulfonium, amino, ammonium, phospho or similar hydrogen bonding groups, connected by or to hydrophobic groups, such as alkylene, alkyl, cycloalkyl, aryl, arylene, aralkyl, polyalkylene, polyalkylyne, combinations of such groups and such groups containing relatively non-polar substituents, such as hydrocarbon, chlorine, fluorine and the like. Sometimes the hydrophobic moieties are larger and contain more atoms than the polar groups in the molecule, having a minimum of two carbon atoms in each group and up to as many as 36 carbon atoms, although the actual ratio of sizes depends greatly on the structure of the hydrophilic moiety. Most commonly, the hydrophobic groups will contain 14 to 22 carbon atoms and will have linear or sheet-like conformations allowing for relatively flat orientation on surfaces.
Polar moieties other than hydrogen bonding ones are not excluded from these compositions and, indeed, may be deliberately included in some structures to improve adsorption and interfacial spreading tendencies. For example, quaternary ammonium groups, while incapable of forming hydrogen bonds, can improve spreading and interfacial adsorption in some applications by way of their highly ionized form which imparts cationic character to the molecules in which they occur and, via coulombic repulsion effects, can improve spreading in a film.
Generally, the TFSA constituents will contain at least two each of the required hydrophilic (polar) and hydrophobic moieties per molecule and commonly will contain many more of each. The effective products, however, must have the three properties described above.
While, as pointed out above, the effective TFSA may be derived from a wide variety of chemical reactants and may contain numerous different groups or moieties, I have found that particularly effective products are those which are described as an acylated polyether polyol having the formula: ##STR4## wherein: A is an alkylene oxide group, --C.sub.i H.sub.2i O--;
O is oxygen;
i is a positive integer from 2 to about 10;
j is a positive integer no greater than about 100;
k is a positive integer no greater than about 100;
N is nitrogen;
R.sup.1 is one of hydrogen, a monovalent hydrocarbon group containing less than about C.sub.11, or [A.sub.L H];
L is a positive integer no greater than about 100;
R is a hydrocarbon moiety of a polyol, a primary or secondary amine, a primary or secondary polyamine, a primary or secondary amino alcohol, or hydrogen; and
m+n is no greater than about 4 when R is other than hydrogen and one of m and n is zero and the other is unity when R is hydrogen,
said acylated polyether polyol being the reaction product of said polyether polyol and a member selected from the class consisting of mono- and polybasic carboxylic acids, acid anhydrides, and iso-, diiso-, and polyisocyanates, said acylated polyether polyol at about 25.degree. C.; (a) being less than about 1% by volume soluble in water and in isooctane; (b) having a solubility parameter in the range of between about 6.9 and about 8.5; and (c) spreading at the interface between distilled water and refined mineral oil to form a film having a thickness no greater than about 20 Angstroms at a spreading pressure of about 16 dynes per cm.
Alternatively, the TFSA constituents may be described as acylated polyether polyols derivable by the reaction of an alkylene oxide containing less than about 10 carbon atoms with a member of the group consisting of polyols, amines, polyamines and amino alcohols containing from between about 2 to about 10 active hydrogen groups capable of reaction with alkylene oxides and the acylating agent being a member selected from the class consisting of mono- and polybasic carboxylic acids, acid anhydrides and iso-, diiso- and polyisocyanates.
Compositions incorporated within the scope of the formula set forth above contain an average of about 11/2 or more hydroxyl groups per molecule and are generally composed of a cogeneric mixture of products obtained by condensing alkylene oxides with smaller molecules containing two or more reactive hydrogens as part of hydroxyl or amino groups.
Representative of these compositions is polypropylene glycol, having an average molecular weight of about 1,200, to which about 20% by weight of ethylene oxide has been added. Such a polyether glycol is theoretically obtainable by condensing about 20 moles of propylene oxide with about one mole of water, followed by addition of about six moles of ethylene oxide. Alternatively, one may condense about 10 moles of propylene oxide with a previously prepared polyethylene glycol of about 240 average molecular weight.
Alkylene oxides suitable for use in preparing the TFSA constituents used in the present solutions include ethylene oxide, proplyene oxide, butylene oxide, 2-3-epoxy-2-methyl butane, trimethylene oxide, tetrahydrofuran, glycidol, and similar oxides containing less than about 10 carbon atoms. Because of their reactivity and relatively low cost, the preferred alkylene oxides for preparing effective TFSA constituents are the 1,2-alkylene oxides (oxiranes) exemplified by ethylene oxide, propylene oxide and butylene oxide. In the preparation of many TFSA constituents, more than one alkylene oxide may be employed either as mixtures of oxides or sequentially to form block additions of individual alkylene oxide groups.
Other suitable dihydric alcohols may be obtained by condensing alkylene oxides or mixtures of oxides or in successive steps (blocks) with difunctional (with respect to oxide addition) compounds, such as ethylene glycol, methyl amine, propylene glycol, hexamethylene glycol, ethyl ethanolamine, analine, resorcinol, hydroquinone and the like.
Trihydric ether alcohols may be prepared by condensation of ethylene, propylene or butylene oxides with, for example, glycerin, ammonia, triethanolamine, diethanolamine, ethyl ethylene diamine or similar smaller molecules containing three hydrogens capable of reacting with alkylene oxides. Similarly, polyether alcohols with a multiplicity of hydroxyl groups may be obtained by condensing alkylene oxides with multireactive starting compounds, such as pentaerythritol, glycerol, N-monobutyl ethylene diamine, trishydroxymethylaminomethane, ethylene diamine, diethylenetriamine, diglycerol, hexamethylene diamine, decylamine and cyclohexylamine. DeGroote, in U.S. Pat. No. 2,679,511, describes a number of amino derived polyols which he subsequently esterfies. Product 15-200, manufactured and sold by the Dow Chemical Company, and derived by oxyalkylation of glycerol with a mixture of ethylene and propylene oxides, is an example of a commercially available polyol of the kind contemplated herein.
Generally, these compositions will have average molecular weights of 15,000 or less and will be derived from reactive hydrogen compounds having 18 or fewer carbon atoms and 10 or fewer reactive hydrogens.
Other general descriptions of suitable compounds coming within the scope of the structure detailed above, along with methods for carrying out the actual manufacturing steps, are disclosed in "High Polymers, Vol. XIII, Polyethers," edited by N. G. Gaylord, John Wiley & Sons, New York, 1963.
Effective TFSA with improved performance may be prepared by acylation of the polyether polyol described above with a mono- or polybasic carboxylic acid, acid anhydride, isocyanate, diisocyanate or other polyisocyanate. An especially useful TFSA may be made by reacting an approximately difunctional polyether polyol with a difunctional carboxylylic acid, acid anhydride or isocyanate to form a polymeric ester or urethane. However, polymerization is not always required, and where effected is usually not carried to the point of including a very large number of monomer units in the molecule. Frequently, effective reagents are obtained where residual, unreacted hydroxyl or carboxyl groups remain in the product or, where a polyisocyanate is used, one or more residual isocyanate groups or amino or substituted urea groups which result from reaction of residual end groups with water, followed by decarboxylation, may remain.
Examples of acylating agents suitable for preparing useful esters include acetic acid, acetic anhydride, butyric acid, benzoic acid, abietic acid, adipic acid, diglycollic acid, phthallic anhydride, fumaric acid, hydroxyacetic acid, itaconic acid, succinic acid, dimerized fatty acids and the like. I have found the most generally useful acylating agents to be the di- and mono-basic acids and anhydrides containing less than 13 carbon atoms.
Examples of isocyanates useful for the acylation of a polyether polyol to produce an effective TFSA include methylisocyante, phenyl isocyanate, cyclohexylmethylene isocyanate, and the like. Especially useful reactants are polyisocyanates containing two or more isocyanate groups and including phenylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, 1,5-Naphthalene diisocyanate and polymethylenepolyphenyl isocyanates.
Following acylation reactions of polyether polyols with polyisocyanates, where a stoichiometric excess of the latter reactant is employed, remaining isocyanate groups may be left as such or may, by appropriate addition of water or monohydric alcohol, be converted to carbamic acid groups, which immediately undergo decarboxylation to yield residual amino groups, or carbamate groups.
Examples of acylated polyether polyols and their manufacturing procedures are well known to the art, as disclosed in U.S. Pat. No. 2,454,808, issued Nov. 30, 1948, to Kirkpatrick, U.S. Pat. No. 2,562,878, issued Aug. 7, 1951, to Blair, U.S. Pat. No. 2,679,511, issued May 25, 1954, to DeGroote, U.S. Pat. No. 2,602,061, issued July 1, 1952, also to DeGroote, "Chemical Process Industries" by R. N. Shreve, McGraw Hill Publishing Co., 1967, page 654 et seq., and "High Polymers", Vol. XIII, edited by N. G. Gaylord, John Wiley & Sons, 1963, page 317 et seq., the disclosure of each of which is hereby incorporated by reference.
As to the limits of the various constituents of the micellar solutions containing TFSA, the following will serve as a guide, the percentages being by weight:
Although the exact function of the electrolytes previously referred to is not completely understood, the effect, in part, may be due to the ability to bind water, i.e., to become hydrated. This suggests that certain other materials which are highly hydrophile in character and clearly differentiated from the classes of non-polar solvents and semi-polar solubilizers may be the functional equivalent of an electrolyte. Substances of this class which ordinarily do not dissociate include glycerol, ethylene glycol, diglycerol, sugar, glucose, sorbitol, mannitol, and the like.
Also, as stated above, these solutions may contain other organic constituents such as hydrocarbons. These frequently are used as thinning agents, azetropic distillation aids or reflux temperature controllers in the manufacture of the TFSA constituent and may be left therein when the present micellar solutions are prepared. To the extent that such compounds are present they appear to compete somewhat with the TFSA constituents for micelle space, thus limiting, to some extent, the maximum amount of TFSA constituent which can be brought into homogeneous solution.
Selection of an effective TFSA composition for a given petroleum emulsion and determination of the amount required is usually made by so-called "bottle tests", conducted, in a typical situation, as follows:
A sample of fresh emulsion is obtained and 100 ml portions are poured into each of several 180 ml screw top prescription or similar graduated bottles. Dilute solutions (1% or 2%) of various TFSA constituents are prepared in isopropyl alcohol. By means of a graduated pipette, a small volume of a TFSA solution is added to a bottle. A similar volume of each composition is added to other bottles containing emulsion. The bottles are then closed and transferred to a water bath held at the same temperature as that employed in the field treating plant. After reaching this temperature, the bottles are shaken briskly for several minutes.
After the shaking period, the bottles are placed upright in the water bath and allowed to stand quietly. Periodically, the volume of the separated water layer is recorded along with observations on the sharpness of the oil-water interface, appearance of the oil and clarity of the water phase.
After the standing period, which may range from 30 minutes to several hours, depending upon the temperature, the viscosity of the emulsion and the amount of TFSA compositions used, small samples of the oil are removed by pipette or syringe and centrifuged to determine the amount of free and emulsified water left in the oil. The pipette or syringe used to remove the test samples should be fitted through a stopper or other device which acts as a position guide to insure that all bottles are sampled at the same fluid level.
The combined information on residual water and emulsion, speed of the water separation and interface appearance provides the basis for selection of the generally most effective TFSA constituent. Where none of the results are satisfactory, the tests should be repeated using higher concentrations of TFSA constituents and, conversely, where all results are good and similar, the tests should be repeated at lower concentrations until good discrimination is possible.
In practicing the process for resolving petroleum emulsions of the water-in oil type with the present micellar solution, such solution is brought into contact with or caused to act upon the emulsion to be treated, in any of the various methods or apparatus now generally used to resolve or break petroleum emulsions with a chemical reagent, the above procedure being used alone or in combination with other demulsifying procedure, such as the electrical dehydration process.
One type of procedure is to accumulate a volume of emulsified oil in a tank and conduct a bath treatment type of demulsification procedure to recover clean oil. In this procedure, the emulsion is admixed with the micellar TFSA solution, for example, by agitating the tank of emulsion and slowly dripping the micellar TFSA solution into the emulsion. In some cases, mixing is achieved by heating the emulsion while dripping in the micellar TFSA solution, depending upon the convection currents in the emulsion to produce satisfactory admixture. In a third modification of this type of treatment, a circulating pump withdraws emulsion from, e.g., the bottom of the tank and reintroduces it into the top of the tank, the micellar TFSA solution being added, for example, at the suction side of said circulating pump.
In a second type of treating procedure, the micellar TFSA solution is introduced into the well fluids at the wellhead, or at some point between the wellhead and the final oil storage tank, by means of an adjustable proportioning mechanism or proportioning pump. Ordinarily, the flow of fluids through the subsequent lines and fittings suffices to produce the desired degree of mixing of micellar TFSA solution and emulsion, although, in some instances, additional mixing devices may be introduced into the flow system. In this general procedure, the system may include various mechanical devices for withdrawing free water, separating entrained water, or accomplishing quiescent settling of the chemically treated emulsion. Heating devices may likewise be incorporated in any of the treating procedures described herein.
A third type of application (down-the-hole) of micellar TFSA solution to emulsion is to introduce the micellar solution either periodically or continuously in diluted form into the well and to allow it to come to the surface with the well fluids, and then to flow the chemical-containing emulsion through any desirable surface equipment, such as employed in the other treating procedures. This particular type of application is especially useful when the micellar solution is used in connection with acidification of calcareous oil-bearing strata, especially if dissolved in the acid employed for acidification.
In all cases, it will be apparent from the foregoing description, the broad process consists simply in introducing a relatively small proportion of micellar TFSA solution into a relatively large proportion of emulsion, admixing the chemical and emulsion either through natural flow, or through special apparatus, with or without the application of heat, and allowing the mixture to stand quiescent until the undesirable water content of the emulsion separates and settles from the mass.
Besides their utility for breaking petroleum emulsions, the present micellar TFSA solutions, as mentioned earlier, may be used to prevent emulsion formation in steam flooding, in secondary waterflooding, in acidizing of oil-producing formations, and the like.
Petroleum oils, even after demulsification, may contain substantial amounts of inorganic salts, either in solid form or as small remaining brine droplets. For this reason, most petroleum oils are desalted prior to refining. The desalting step is effected by adding and mixing with the oil a few volume percentages of fresh water to contact the brine and salt. In the absence of demulsifier, such added water would also become emulsified without effecting its washing action. The present micellar solutions may be added to the fresh water to prevent its emulsification and to aid in phase separation and removal of salt by the desalting process. Alternatively, if desired, they may be added to the oil phase as are present aromatic solvent compositions.
Most petroleum oil, along with its accompanying brines and gases, is corrosive to steel and other metallic structures with which it comes in contact. Well tubing, casing, flow lines, separators and lease tanks are often seriously attacked by well fluids, especially where acidic gases such as H.sub.2 S or CO.sub.2 are produced with the liquids, but also in systems free of such gases.
It has been known for some time, and as exemplified in U.S. Pat. No. 2,466,517, issued Apr. 5, 1949, to Chas. M. Blair and Wm. F. Gross, that such corrosive attack to crude oil fluids can be mitigated or prevented by addition to the fluids of small amounts of organic inhibitors. Effective inhibitors compositions for this use are usually semi-polar, surface active compounds containing a nonpolar hydrocarbon moiety attached to one or more polar groups containing nitrogen, oxygen or sulfur or combinations of such elements. Generally these inhibitors or their salts are soluble in oil and/or water (brine) and frequently appear to be able to form micelles in one or both of these phases. Typical inhibitors include amines such as octyl amine, dodecyl amine, dioctodecyl amine, butyl naphthyl amine, dicyclohexyl amine, benzyl dimethyldodecyl ammonium chloride, hexadecylaminopropyl amine, decyloxypropyl amine, mixed amines prepared by hydrogenation of nitrile derivatives of tall oil fatty acids, soya acid esters of monoethanol amine, 2-undecyl, 1-amino ethyl imidazoline and a wide variety of cationic nitrogen compounds of semi-polar character. Also effective in some applications are nonyl succinic acid, diocylnaphthalene sulfonic acid, trimeric and dimeric fatty acids, propargyl alcohol, mercaptobenzothiozole, 2, 4, 6-trimethyl-1, 3, 5-trithiaane, hexadecyldimethyl benzimidazolium bromide, 2-thiobutyl-N-tetrodecylpyridinium chloride, tetrahydronaphthylthiomorpholine, and the like.
In contrast to the TFSA, corrosion inhibitors appear to function by forming on the metal surface strongly adherent, thick, closely packed films which prevent or lessen contact of corrosive fluids and gases with the metal and interfere with ionic and electron transfer reactions involved in the corrosion process.
Corrosion inhibitors are quite commonly introduced down the casing annulus of oil wells where they commingle with the well fluids before their travel up the well tubing and thus can effectively prevent corrosion of well equipment. Where corrosive attack occurs at the surface, the inhibitor may be introduced at or near the well head, allowing it to adsorb on the flow lines and surface equipment to insure protection.
Addition of inhibitor at either downhole or surface locations may be combined conveniently with demulsifier addition since the latter is also frequently introduced in one of these locations.
Inhibitors such as those mentioned above, may generally be incorporated into the TFSA micellar solutions, replacing a portion of or in addition to the TFSA constituent. Also, since many of these inhibitors are themselves micelle-forming amphipathic agents, they may be included in the micellar solution as such, replacing other amphipathic agents which might be otherwise utilized. Combining the micellar solution with corrosion inhibitor permits more economic chemical treatment by reducing inventory to one compound, requiring only one chemical injection system rather than two and lessening the labor and supervision required.
Still another important effect of using the micellar solution of TFSA and corrosion inhibitor results from the prevention of emulsification by the inhibitor. Frequently, it has been found that inhibitor in the amount required for effective protection causes the formation of very refractive emulsions of water and hydrocarbon, especially in systems containing light, normally nonemulsifying hydrocarbons such as distillate, casing head gasoline, kerosene, diesel fuel and various refinery fractions. Inhibitors are commonly used in refinery systems where emulsification is highly objectionable and where the compositions could be designed to include an effective emulsion preventative micellar solution of TFSA.
Inhibitor use may range from a few to several hundred parts per million based on the oil to be treated, depending upon the severity of corrosion. For a given oil field or group of wells, tests will normally be run to determine the requirement for micellar solution of TFSA and for inhibitor and a composition incorporating these components in approximately the desired ratio will be prepared. In some instances, the requirement for micellar solution of TFSA in the best concentration may result in use of corrosion inhibitor, employed as micelle-former, in some excess over that required for inhibition. This will not affect the utility of the micellar solution and will provide a comfortable excess of inhibition which can be helpful during the periods when higher corrosivity may be encountered.
Examples of micellar solutions employing TFSA with inhibitor in water dispersible, micellar solutions are given below.
Selection of the proper corrosion inhibitor for a given system or oil is usually made by conducting laboratory tests under conditions simulating those encountered in the well or flowline. 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, Tex.
EXAMPLES OF THIN FILM SPREADING AGENTS
EXAMPLE I
Reference is made to U.S. Pat. No. 2,562,878, dated Aug. 7, 1951, to Chas. M. Blair, Jr., which describes the preparation of demulsifiers which are polyesters of dicarboxylic acids and polyhydric alkylene ether glycols. Using the procedure described therein, 150 lbs. of diglycolic acid was reacted with 2,000 lbs. of "Pluronic L-62" manufactured by Wyandotte Chemical Corporation of Wyandotte, Mich. "Pluronic L-62" is described as a polypropylene glycol having a molecular weight of about 1,650 to which has been added and condensed therewith about 25% by weight of ethylene oxide.
The esterification reaction was continued until the acid number of the reaction mixture had dropped to about 15.
The resulting product was a moderately viscous liquid, insoluble to the extent of 1% in either water or isooctane, had a Solubility Parameter of 8.1, and spread at the interface between white mineral oil and water at 25.degree. C. to yield a film pressure of 22 dynes per cm at a calculated thickness of 14 Angstroms.
EXAMPLE II
Using the procedure described by C. H. M. Roberts in U.S. Pat. No. 1,977,146, dated Oct. 23, 1934, one mole each of the mono- and diglycerides of ricinoleic acid were reacted with three moles of phthallic anhydride. The reaction was stopped short of gelation to yield a viscous, reddish polymer, insoluble in water and isooctane, having a solubility parameter of 8.4 and spreading at the white oil-distilled water interface with a pressure of 20 dynes per cm at a calculated thickness of 10 Angstroms.
EXAMPLE III
To 1,000 parts of commercial polyoxypropylene glycol of molecular weight of about 2,000 was added 200 parts of ethylene oxide. Reaction was conducted as in Example I. After completion of the ethylene oxide addition, a mild vacuum was applied for 30 minutes to remove any unreacted oxide. The temperature was lowered to 40.degree. C. and 5 parts of dodecylbenzene sulfonic acid were added to the reaction mass while stirring. Eighty parts of phenyacetic acid were then introduced and heating and stirring were commenced under a take-off condensor. The temperature was slowly raised to about 160.degree. C. over a three-hour period and was held at this temperature for an additional 2 hours.
The product was then cooled and drummed. It was an effective demulsifier especially for petroleum emulsions encountered in southern Louisiana, and met the criteria recited previously for such interfacially active compounds.
EXAMPLE IV
Two and one-half parts of tris-hydroxymethylaminomethane were substituted for the dipropylene glycol in Example I of my co-pending application Ser. No. 082,349, filed Oct. 5, 1979, entitled "Petroleum Demulsifiers Comprising A Polyether Polyol", the disclosure of which is herein incorporated by reference.
To the above product was added with stirring 5 parts of maleic anhydride. The temperature was then raised to 130.degree. C. while the vessel was open to a take-off condensor. Stirring and heating were continued until a sample of the reaction mass had a viscosity in the range of 900 to 1,100 centipoises at 80.degree. C.
This product was an effective thin film spreading agent and especially useful as a demulsifier for petroleum emulsions occurring in western Kansas and in Kuwait.
EXAMPLE V
Using the apparatus and procedure of Example I, 4,000 lbs. of polypropylene glycol of average molecular weight 1,200 was condensed with 700 lbs. of ethylene oxide. Forty pounds of potassium hydroxide was dissolved in the polypropylene glycol prior to oxide addition, which was carried out within the temperature range of about 140.degree.-160.degree. C. under a maximum pressure of about 75 psi.
After completion of the above reaction, the temperature was lowered to about 60.degree. C. and the reaction vessel was connected to a take-off condensor. Fifty pounds of 85% phosphoric acid was slowly added to the reaction mass with stirring followed by 314 lbs. of adipic acid. The temperature was then slowly brought to 145.degree.-155.degree. C. while continuing to stir and to distill water from the reaction mixture. The acid number of the product was periodically determined. When a valve between 10 and 15 mg. KOH per gm. was reached, heating was stopped, the product was cooled to room temperature and filled into 55-gallon drums.
This product has a calculated equivalent weight in excess of 4,000, is insoluble to the extent of 1% in water and isooctane, has a solubility parameter of 7.9 and rapidly spreads at the interface between white oil and distilled water, at 25.degree. C., to give a film pressure of 18 dynes per cm at a calculated thickness of 18 Angstroms.
EXAMPLE VI
Into a 1,000 gal. stainless steel autoclave, equipped with steam jacket, internal cooling coils, stirrer, condensor and several inlet feed lines were place 92 lbs. of glycerol. 2,750 lbs. of a mixture of 2,250 lbs. of propylene oxide and 500 lbs. of ethylene oxide was prepared in a separate weighed feed tank. Twelve pounds of a 50% aqueous solution of potassium hydroxide was stirred into the glycerol while heating to about 120.degree. C. During this period, the vessel was connected to a steam jet vacuum system through the condensor, arranged in take-off position. Stirring under vacuum was continued until the evolution of water had effectively ceased.
The vessel was then closed and the mixed oxides were introduced slowly. The resulting exothermic reaction was controlled by the oxide addition rate such as to allow a slow increase in temperature to about 150.degree. C. After the addition of about 800 lbs. of oxides the rate of reaction declined. The oxide addition line was then closed, the temperature lowered to 110.degree. C., the vessel was vented briefly to the vacuum jet, and an additional 25 lbs. of 50% aqueous solution of potassium hydroxide was introduced into the reaction mass which was then stirred under vacuum at 120.degree.-140.degree. C. until water evolution ceased.
The vessel was closed, the oxide inlet line was again opened and reaction was continued with the fresh catalyst, holding the temperature at about 150.degree. C. under a maximum pressure of about 50 psi until the whole of the 2,750 lbs. of mixed oxide had been reacted.
After cooling this batch to about 120.degree. C., 1,860 lbs. of commercial mixed xylene was pumped into the autoclave and the whole was stirred and adjusted to a temperature of about 95.degree. C. A solution of 125 lbs. of toluene diisocyanate in 200 lbs. of xylene was then slowly pumped into the vessel while maintaining the temperature at 100.degree..+-.5.degree. C. for approximately the two hours required for the addition. The temperature was then raised to 140.degree. C. and stirring was continued until the viscosity at 100.degree. C. was within the range of 1,000 to 1,500 centipoises. Heating was then discontinued and the batch was cooled quickly to allow transfer to storage.
A sample of this product, after removal of xylene by vacuum distillation was found to meet the three criteria for a TFSA.
EXAMPLES OF MICELLAR SOLUTIONS OF TFSA's
EXAMPLE A
Besides having good demulsification action, this product is an effective corrosion inhibitor for down-the-hole use, the imidazoline used as the amphipathic agent being a strongly adsorbed inhibitor for steel in anaerobic systems.
EXAMPLE B
This clear, homogeneous solution is quite acidic. It can be combined with 15% hydrochloric acid used for acidizing calcareous oil-producing formations and acts therein to prevent emulsification of acid and spent acid.
EXAMPLE C
This is a clear, homogeneous but viscous solution.
EXAMPLE D
EXAMPLE E
This product may be diluted further with water to form clear to slightly opalescent solutions.
EXAMPLE F
This product is an effective micellar composition for numerous petroleum emulsions, but is especially effective as a component in synergistic blends with the composition of Example B and with other compositions such as those disclosed in my co-pending applications, Ser. Nos. 45,479, 45,478, 45,360 and 45,470, cited in detail, above.
The product of Example F has also been found to be an effective waterflood additive, especially in combination with aqueous micellar solutions of resinous polyoxide adducts such as those described in my co-pending application, Ser. No. 082,253, filed Oct. 5, 1979, and entitled, "Micellar Solutions Of Thin Film Spreading Agents Comprising Resinous Polyalkylene Oxide Adducts".
EXAMPLE G
This product is a very viscous, redish liquid, readily dispersible in water to form slightly opalescent solutions. It is effective alone or in combination with other aqueous systems or diluted in water as a flooding agent for oil recovery, especially where a higher viscosity agent is needed for mobility control.
Further, it is an effective demulsifier for heavy oil emulsion produced in the McKittrick, Calif. field and is even more effective in a 50-50 blend with the composition of Example E.
Still further, this product is found to assist in the flocculation and sedimentation of finely ground hematite particles during the decantation of aqueous slurries of the ground ore to remove sand and clay minerals and effect beneficiation of the iron-containing values.
Among procedures which have been found useful in selecting effective micellar TFSA solutions for this use, one involves a determination of oil displacement efficiency from prepared oil-containing rock cores in equipment described below. A tube of glass or transparent polymethacrylate ester, having an inside diameter of about 3.5 cm (11/2 in.) and a length of about 45 cm (18 in.), is fitted with inlet connections and appropriate valves at each end. The tube is mounted vertically on a rack in an air bath equipped with a fan, heater and thermostat which allows selection and maintenance of temperatures in the range of between about 25.degree.-130.degree. C.
To select an effective micellar TFSA solution for use in a given oil formation, samples of the oil, of the producing rock formation and of the water to be used in the flooding operation were obtained. The formation rock is extracted with toluene to remove oil, is dried and is then ground in a ball mill to the point where a large percentage passes a 40 mesh sieve. The fraction between 60 and 100 mesh in size is retained. The tube described above is removed from the air bath, opened and, after insertion of a glass wool retainer at the lower end, is packed with the ground formation rock. The tube is tapped gently from time-to-time during fillings to ensure close packing and is visually inspected to assure absence of voids.
The tube is then returned to the air bath, connected to the inlet tubing, the temperature is adjusted to the oil formation temperature and water representative of that produced from the formation is admitted slowly through the bottom line from a calibrated reservoir in an amount just sufficient to fill the packed rock plug in the tube. This volume is determined from the calibrations and is referred to as the "pore volume", being that volume of water just sufficient to fill the pores or interstices of the packed plug rock.
The upper line to the reservoir is then connected to a calibrated reservoir containing the oil representing that from the formation to be flooded. By proper manipulation of valves, the line is filled with oil which is then slowly pumped into the core from the reservoir after the lower valve is opened to allow displacement of the formation water.
As breakthrough of oil at the bottom is noted, pumping is stopped and the volume of oil introduced into the sand is determined from the reservoir readings. This is referred to as the volume of oil in place. The tube of sand containing oil is then left in the air bath at the temperature of the formation for a period of three days to allow establishment of equilibrium between the ground formation rock and the oil with respect to adsorption of oil constituents on the rock and lowering of interfacial tension. The time allowed for equilibrium may be varied widely. At higher temperatures, the time required to reach equilibrium is probably reduced. Usually, for comparative tests, three days are allowed to age the oil-rock plug. Results with this procedure closely simulate work with actual cores of oil-bearing rock.
The oil and water samples used for test purposes are preferably taken under an inert gas such as high purity nitrogen, and are maintained out of contact with air during all miniuplations in order to prevent oxidation of the oil and concomitant introduction of spurious polar, surface-active constituents in the oil. At this point, the rock-oil system simulates the original oil formation before primary production oil has commenced and well before any secondary waterflood operation.
The upper inlet line to the tube is now connected to the sample of water used in the flooding of the oil formation and, by means of a syringe pump or similar very small volume positive displacement pump, the water is pumped into the sand body from the top to displace fluids out of the bottom tubing connection into a calibrated receiver. The pumping rate is adjusted to one simulating the rate of flood water advance in an actual operation, which is usually in a range of 1 to 50 cm per day. Pumping is maintained at this rate until two pore volumes of water have been pumped through the sand.
The volumes of fluids collected in the receiver are measured and the relative amount of oil and water displaced from the rock sample are determined and recorded. Of special interest is the volume of oil displaced as a fraction of the original pore volume. This information may be viewed as an indication of the approximate percentage of oil originally in place which is produced by natural water drive following drilling of a well into the rock formation followed by the primary phase of field production carried to the approximate economic limit.
Following this step, one to three additional pore volumes of water containing the TFSA micellar solution to be tested are pumped slowly through the plug and the volumes of additional oil and water displaced are determined. Typically, where such an initial "slug" of micellar TFSA solution is introduced, it may be contained in a volume of fluid ranging from 1% to 100% of the pore volume, but most frequently it will be in a slug volume of 10% to 50% of pore volume.
After this final displacement step, the produced oil and water are again measured. By comparing the amount of oil produced by this additional injection of water containing, or preceded by a solution, of micellar TFSA solution with the amount produced when the same volume of water containing no TFSA solution is injected, one can evaluate the effectiveness of the particular micellar TFSA solution used for enhancing the recovery of additional oil over and above that obtained by ordinary waterflooding.
Generally, six or more sand columns of the kind described above are mounted in the heated air bath. Test of a given micellar TFSA solution is then run in triplicate, using identical conditions and concentrations, simultaneously with three blank tests run similarly but without addition of micellar TFSA solution to the water.
The composition of Example D was tested by this procedure with the following conditions:
Oil was displaced by pumping two pore volumes of water into the sand. After measuring the volumes of oil and water produced through the bottom line, a further 0.2 pore volumes of water containing 2,600 ppm of the composition of Example F was injected followed by 2.8 volumes of water containing 175 ppm of the composition of Example D. Measurement of the volumes of oil and water produced were read after each 0.2 pore volumes of water was injected.
Results of this test at the points of 2,3 and 5 pore volumes of injected water are given in the table below wherein averages of three duplicate determinations are presented.
Use of the composition of Example F in the amounts given above resulted in the production of 110% more oil from injection of one incremental pore volume of water than was produced by water injection alone and gave 150% more oil after three incremental pore volumes of treated water injection.
Although the invention has been described in terms of specified embodiments which are set forth in detail, it should be understood that this is by illustration only and that the invention is not necessarily limited thereto, since alternative embodiments and operating techniques will become apparent to those skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing from the spirit of the described invention.
Claims
What is claimed and desired to be secured by Letters Patent is:
1. A homogeneous micellar thin film spreading agent solution, comprising: (1) from between about 5% and about 75% by weight of an acylated polyether polyol having the formula: ##STR5## wherein: A is an alkylene oxide group, --C.sub.i H.sub.2i O--; O is oxygen; i is a positive integer from 2 to about 10; j is a positive integer no greater than about 100; k is a positive integer no greater than about 100; N is nitrogen; R.sup.1 is one of hydrogen, a monovalent hydrocarbon group containing less than about C.sub.11, or [A.sub.L H]; L is a positive integer no greater than about 100; R is a hydrocarbon moiety of a polyol, a primary or secondary amine, a primary or secondary polyamine, a primary or secondary amino alcohol, or hydrogen; and m+n is no greater than about 4 when R is other than hydrogen and one of m and n is zero and the other is unity when R is hydrogen. said acylated polyether polyol being the reaction product of said polyether polyol and a member selected from the class consisting of mono- and polybasic carboxylic acids, acid anhydrides, and iso-, diiso-, and polyisocyanates, said acylated polyether polyol at about 25.degree. C.: (a) being less than about 1% by volume soluble in water and in isooctane; (b) having a solubility parameter in the range of between about 6.9 and about 8.5; and (c) spreading at the interface between distilled water and refined mineral oil to form a spreading film having a thickness no greater than about 20 Angstroms at a film pressure of about 16 dynes per cm; (1) from between about 2% and about 30% by weight of a hydrotropic agent having one of the formulas: wherein X is an alkyl, alicyclic, aromatic, alkylalicyclic, alkylaryl, arylalkyl, alicyclicalkyl, heterocyclic or substituted heterocyclic radical having 2 to 13 carbon atoms; and wherein Z is one of: ##STR6## where U and V are hydrogen or hydrocarbon substituents; wherein: Z is one of ##STR7## X is an alkyl, alicyclic, aromatic, alkylalicyclic, alkylaryl, arylalkyl, alicyclicalkyl, heterocyclic or substituted heterocyclic radical having 2 to 12 carbon atoms; R is a member selected from the class consisting of, --CH.sub.2 --, --C.sub.2 H.sub.4 --, C.sub.3 H.sub.5 .dbd., --C.sub.3 H.sub.6, and --C.sub.2 H.sub.4 --O--C.sub.2 H.sub.4 --; n is either a one or two integer, the integer dependent upon the selection of R; Y is a member selected from the class consisting of: ##STR8## and U and V are hydrogen or hydrocarbon substituents; (3) from between about 2% and about 30% by weight of an amphipathic agent having at least one radical having from between about 10 and about 64 carbon atoms per molecule; and (4) from between about 15% and about 90% by weight, water.
2. The composition of claim 1 wherein said acylated polyether polyol is the reaction product of a difunctional polyether polyol and a difunctional member of the class consisting of carboxylic acids, acid anhydrides and isocyanates.
3. The composition of claim 1 wherein said acylated polyether polyol is the reaction product of a polyether polyol and an acylating agent selected from the class consisting of di- and mono-basic acids and anhydrides having C.sub.13 or less.
4. The composition of claim 1 wherein said acylated polyether polyol is the reaction product of a polyether polyol and a polyisocyanate containing at least two isocyanate groups.
5. The composition of claim 1 wherein the hydrotropic agent is an alcohol.
6. The composition of claim 1 wherein the hydrotropic agent is an aldehyde.
7. The composition of claim 1 wherein the hydrotropic agent is a semi-polar oxygen-containing compound capable of forming hydrogen bonds.
8. The composition of claim 1 wherein the hydrotropic agent is an amine.
9. The composition of claim 1 wherein the hydrotropic agent is a carboxy amide.
10. The composition of claim 1 wherein the hydrotropic agent is a phenolate.
11. The composition of claim 1 wherein the amphipathic agent is a hydrophobic hydrocarbon residue-containing composition wherein the hydrocarbon residue is aliphatic, alkylalicyclic, aromatic, arylalkyl or alkylaromatic.
12. The composition of claim 1 wherein the amphipathic agent contains an uninterrupted chain of from between about 10 and about 22 carbons.
13. The composition of claim 1 wherein the amphipathic agent is an anion-active soap.
14. The composition of claim 1 wherein the amphipathic agent comprises ammonium lauryl sulfonate.
15. The composition of claim 1 wherein the amphipathic agent comprises mahogany or green sulfonates of petroleum, petroleum fractions, or petroleum extracts.
16. The composition of claim 1 wherein the amphipathic agent comprises dodecylbenzene sulfonate.
17. The composition of claim 1 wherein the amphipathic agent comprises cetyl pyridinium chloride.
18. The composition of claim 1 wherein the amphipathic agent comprises dimethyl-pentadecyl sulfonium bromide.
19. The composition of claim 1 wherein the amphipathic agent comprises octadecylamine acetate.
20. The composition of claim 1 wherein the amphipathic agent comprises 2-heptadecyl-3-diethylene diamino-imidazoline diacetate.
21. The composition of claim 1 wherein the amphipathic agent comprises the oleic acid ester of nonaethylene glycol.
22. The composition of claim 1 wherein the amphipathic agent comprises an oxyethylated alkylphenol.
23. The composition of claim 1 wherein the amphipathic agent comprises an alcohol ether of a polyethylene glycol.
24. The composition of claim 1 wherein the amphipathic agent is anionic.
25. The composition of claim 1 wherein the amphipathic agent is cationic.
26. The composition of claim 1 wherein the amphipathic agent is nonionic.
27. A homogeneous micellar thin film spreading agent solution, comprising: (1) from between about 5% and about 75% by weight of an acylated polyether polyol wherein said polyether polyol has an average molecular weight of 15,000 or less and is derived from the reaction of an alkylene oxide containing less than about 10 carbon atoms with a member of the group consisting of polyols, amines, polyamines and amino alcohols containing from about 2 to about 10 active hydrogen groups capable of reaction with alkylene oxides, said member having 18 or less carbon atoms, and the acylating agent being a member selected from the class consisting of mono- and polybasic carboxylic acids, acid anhydrides and iso-, diiso-, and polyisocyanates, said acylated polyether polyol, at about 25.degree. C.: (A) having a solubility in water and isooctane at about 25.degree. C. of less than about 1%, by volume; (B) having a solubility parameter from between about 6.8 and about 8.5; and (C) spreading at the interface between white, refined mineral oil and distilled water to form a film having a calculated thickness no greater than about 20 Angstroms, at a spreading pressure of about 16 dynes per cm; (2) from between about 2% and about 30% by weight of a hydrotropic agent comprising a semi-polar hydrogen bond forming compound containing at least one of oxygen, nitrogen and sulfur and from between about 2 and about 12 carbon atoms; (3) from between about 2% and about 20% by weight of an amphipathic agent having at least one radical having from between about 10 and about 64 carbon atoms per molecule; and (4) from between about 15% and about 90% by weight, water.
28. The composition of claim 27 wherein the solubility parameter at about 25.degree. C. of the acylated polyether polyol is from between about 7.1 and about 7.9.
29. The composition of claim 27 wherein the hydrotropic agent is an alcohol.
30. The composition of claim 27 wherein the hydrotropic agent is an aldehyde.
31. The composition of claim 27 wherein the hydrotropic agent is a semi-polar oxygen-containing compound capable of forming hydrogen bonds.
32. The composition of claim 27 wherein the hydrotropic agent is an amine.
33. The composition of claim 27 wherein the hydrotropic agent is a carboxy amide.
34. The composition of claim 27 wherein the hydrotropic agent is a phenolate.
35. The composition of claim 27 wherein the amphipathic agent is a hydrophobic hydrocarbon residue-containing composition wherein the hydrocarbon residue is aliphatic, alkylalicyclic, aromatic, arylalkyl or alkylaromatic.
36. The composition of claim 27 wherein the amphipathic agent contains an uninterrupted chain of from between about 10 and about 22 carbons.
37. The composition of claim 27 wherein the amphipathic agent is an anion-active soap.
38. The composition of claim 27 wherein the amphipathic agent comprises ammonium lauryl sulfonate.
39. The composition of claim 27 wherein the amphipathic agent comprises mahogany or green sulfonates of petroleum, petroleum fractions, or petroleum extracts.
40. The composition of claim 27 wherein the amphipathic agent comprises dodecylbenzene sulfonate.
41. The composition of claim 27 wherein the amphipathic agent comprises cetyl pyridinium chloride.
42. The composition of claim 27 wherein the amphipathic agent comprises dimethyl-pentadecyl sulfonium bromide.
43. The composition of claim 27 wherein the amphipathic agent comprises octadecylamine acetate.
44. The composition of claim 27 wherein the amphipathic agent comprises 2-heptadecyl-3-diethylene diamino-imidazoline diacetate.
45. The composition of claim 27 wherein the amphipathic agent comprises the oleic acid ester of nonaethylene glycol.
46. The composition of claim 27 wherein the amphipathic agent comprises an oxyethylated alkylphenol.
47. The composition of claim 27 wherein the amphipathic agent comprises an alcohol ether of a polyethylene glycol.
48. The composition of claim 27 wherein the amphipathic agent is anionic.
49. The composition of claim 27 wherein the amphipathic agent is cationic.
50. The composition of claim 27 wherein the amphipathic agent is nonionic.
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