[go: up one dir, main page]

GB2057533A - Oil Displacement Enhanced by Lyothropic Liquid Crystals in Highly Saline Media - Google Patents

Oil Displacement Enhanced by Lyothropic Liquid Crystals in Highly Saline Media Download PDF

Info

Publication number
GB2057533A
GB2057533A GB8018869A GB8018869A GB2057533A GB 2057533 A GB2057533 A GB 2057533A GB 8018869 A GB8018869 A GB 8018869A GB 8018869 A GB8018869 A GB 8018869A GB 2057533 A GB2057533 A GB 2057533A
Authority
GB
United Kingdom
Prior art keywords
surfactant
oil
process according
ethoxylated
cationic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8018869A
Other versions
GB2057533B (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Technology and Engineering Co
Original Assignee
Exxon Research and Engineering Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Exxon Research and Engineering Co filed Critical Exxon Research and Engineering Co
Publication of GB2057533A publication Critical patent/GB2057533A/en
Application granted granted Critical
Publication of GB2057533B publication Critical patent/GB2057533B/en
Expired legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09KMATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/58Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids
    • C09K8/584Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids characterised by the use of specific surfactants

Landscapes

  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Colloid Chemistry (AREA)
  • Emulsifying, Dispersing, Foam-Producing Or Wetting Agents (AREA)
  • Lubricants (AREA)

Abstract

Oil is recovered from an oil- bearing formation by injecting into the formation a liquid to displace oil, driving the liquid through the formation and recovering the displaced oil. The liquid comprises a lamellar liquid crystal which exhibits decreasing viscosities at increasing shear rates and contains (a) 0.5 to 10 vol.% of surfactant of balanced hydrophiliclipophilic character, (b) 0.1 to 20 vol.% of an oil, and (c) brine containing from 5 to 30 wt.% of inorganic salts having sodium chloride as the major component and salts of divalent metals as minor components. o

Description

SPECIFICATION Oil Displacement Enhanced by Lyothropic Liquid Crystals in Highly Saline Media This invention relates to a method of recovering oil from an oil-bearing formation using a liquid containing a surfactant. More particularly, the liquid used to displace oil is a liquid crystal which is especially useful for recovering oil from high brine fields.
The use of microemulsions in secondary and tertiary oil recovery techniques is weli-known. Liquid crystal compositions, however, have not been studied to any extent with respect to their potential for the chemically enhanced recovery of crude oil.
An early work which suggests the use of a surfactant system which may possess a liquid crystalline character for oil recovery is U.S. Patent 3,391,736 (Abdo). This patent describes a positive nonsimple fluid useful for recovering oil which possesses a shear thickening response at low shear rates and shear thinning response at high shear rates based on a carboxylate surfactant system. Both of these properties were later claimed in Canadian Patent No. 921,690 to Murphy who described a system exhibiting birefringence and containing 5994% water, 3-20% oil, 2-1 6% surfactant and 15% alcohol.
U. S. Patent No. 3,954,627 (Dreher and Gogarty) describes a composition useful for stimulating oil wells and containing lamellar micelles exhibiting retro-viscous property. These compositions contain from 4-1 5% surfactant, 30-70% hydrocarbon and 1 5-66% water, and optionally a co-surfactant and up to 5 wt.% of an electrolyte. They are birefringent and are probably liquid crystalline in nature.
Related patents are U.S. Patent Nos. 3,948,782 and 3,928,215.
More recently, Dreher et al (J. Coll. and Inters. Sci. 57, 379-387 (1976)) studied a system composed of alkylbenzene sulfonate, hydrocarbon, water and co-surfactant as a model for a tertiary oil recovery fluid. The rheological properties indicated that this system could exist as either a microemulsion or liquid crystal depending on the particular composition. Further studies on certain alkaryl and petroleum sulfonates indicate that liquid crystalline phases can be formed and the formation of these phases are of interest for chemically enhanced oil recovery since they can affect, for example, interfacial tension, viscosity, and retention. For reference, see articles in the Preprints, Div. Petr. Chem., A.C.S., 23(2), 644 (1978) by Scriven et al and ibid., 23(2), 682 (1978) by Miller et al.
Finally, Shah et al in the J. Amer. Oil Chem. Soc., 55, 367 (1978) disclosed a surfactant system based on a mixture of petroleum sulfonate and ethoxylated alkane sulfonate in brine which was tolerant to salts including large amounts of CaCI2 and MgCl2. At certain salt concentrations, it was reported that a stable birefringent phase formed.
In spite of the hypotheses of the above articles, it is generally believed in the art that liquid crystals are not a practical fluid for oil displacement. The reason for this is the high viscosity associated with liquid crystals. For example, Reed and Healy in an article entitled, "Some Physicochernical Aspects of Microemulsion Flooding: A Review", which appeared in the monograph Improved Oil Recovery by Surfactant and Polymer Flooding, Shah and Schechter, Academic Press, N.Y., 1 977, emphasized in part D, especially Page 402, that the excessive viscosity associated with lamellar structures would prohibit application of these compositions to tertiary oil recovery. This pessimism is reflected in the absence of published experiments wherein liquid crystals were used to displace oil.In addition to viscosity considerations, high brine concentrations provide an additional negative factor since it is generally believed that high salt concentrations destabilize liquid crystals.
It would be highly desirable to show that lyotropic liquid crystals containing minor amounts of surfactants and oil are stable in the presence of highly concentrated brine and provide an alternative and improved means to displace oil as compared to microemulsions.
It has now been discovered that lyotropic liquid crystals containing minor amounts of surfactants are stable in the presence of highly concentrated brine and that the liquid crystals can be used to effectively displace oil. Accordingly, the present invention relates to a process for recovering oil from an oil-bearing formation by displacing oil with a primary displacement fluid containing liquid crystals.The process according to the invention comprises injecting into the formation a liquid containing an effective amount of a surfactant to displace oil, said liquid comprising a liquid crystal containing (a) from 0.05 to 10 vol.% of surfactant, (b) 0.1 to 20 vol.% of oil and (c) brine containing 5 to 30 wt.%, based on water, of inorganic salts comprising sodium chloride and salts of divalent metals driving the liquid through the formation and recovering the displaced oil.
!n spite of the high viscosity and known tendency to destabilize at high brine concentrations, it has been found that liquid crystals can be used for oil displacement at least as effectively as microemulsions of comparable composition. The formation of liquid crystals in high brine generally requires somewhat higher molecular weight surfactants at slightly higher concentrations than the formation of microemulsions. On the other hand, liquid crystals possess higher integrity, i.e., less miscibility, and lead to an earlier banking of oil and greater recovery over comparable microemulsions at high brine.
Figure 1 is a graph showing the comparison of oil recovery by liquid crystal versus microemulsion.
Figure 2 is a graph illustrating the effect on oil recovery by liquid crystals based on different combined surfactants.
Figure 3 is a graph demonstrating oil recovery by liquid crystals containing different hydrocarbons as oils.
Figure 4 is a graph of oil recovery by a liquid crystal versus a microemulsion prepared from the same surfactant system.
Figure 5 is a copy of photomicrographs of liquid crystalline phases.
Liquid crystals can be recognized by their anisotropic character. For example, they exhibit birefringence with polarizing microscopy. The present liquid crystals are more highly ordered than known micellar fluids and preferably have a lamellar structure as indicated by microscopy and proven by X-ray diffraction studies.
The essential components of liquid crystals are minor amounts of surfactants and major amounts of brine. These compositions contain minor amounts of oil and may also contain optional additives such as co-solvents, co-surfactants, hydrotropes, chelating agents and polymers.
The compositions of the present invention contain from 0.5 to 10, preferably 0.5 to 3.8 vol.% of surfactant; from up to 25, preferably 0.1 to 20 and particularly 0.5 to 10 vol.% of oil and the balance water containing up to 30 wt.%, based on water, of inorganic salts. The total inorganic salt concentration is from 5 to 30 wt.%. These brines have sodium chloride preferably as the major component together with salts of divalent metals such as Ca2+ and Mg2+, preferably as minor component.
The oil component of the liquid crystal may be a crude oil or a distillate hydrocarbon oil product such as a pentane-hexane mixture, diesel fuel, gas oil, lubricating oil or alkyl benzenes. The nonsulfonated residual hydrocarbon oil of sulfonic acid components is preferably incorporated into the present compositions. In the case of technical petroleum sulfonates, this oil is often a major component of the surfactant. Such surfactants may be employed for liquid crystal preparation without added hydrocarbons.
Different hydrocarbons have a varying ability to stabilize liquid crystals. Crude oil often is less preferred than detergent range paraffins, e.g., those in diesel fuel (such as n-decane) or gas oil from the viewpoint of liquid crystal stability. If crude oil is used, it should preferably have a similar composition to that of the oil field where oil recovery is to be enhanced. It may also contain added salts such as sodium silicates, sodium phosphates and phosphites.
The surfactants which are the active ingredients in the liquid crystals can be anionic, cationic, nonionic, amphoteric, combined anionic and cationic or mixtures thereof. Ethoxylated and/or propoxylated surfactants either alone or in combination with other surfactants are preferred.
Anionic surfactants are carboxylates, sulfonates, sulfates, phenolates and esters of phosphorus acids. Preferred anionic surfactants are sulfonates, sulfates, phosphates, phosphonates and phosphinates.
Surfactant carboxylates include C12 to C40 aliphatic carboxylates and C16 to C40 alkaryl carboxylates wherein the alkyl chain has at least 12 carbon atoms. The aliphatic carboxylates can be open chain and isocyclic. Examples of open chain carboxylic acids are tall oil, palmitic, oleic, hydroxystearic, linoleic, linolenic, undecylenic, aluric, perfluorodecanoic acids. Among the isocyclic compounds, naphthenic acids, rosin acids such as abietic acid and cholic acids are exemplary.
Aromatic carboxylic acids include dodecyibenzoic acid, octadecylsalicylic acid, hexadecyloxybenzoic acid. Substituted carboxylic acids are exemplified by the N-aceylsarcosinates derived from fatty acids and N-methyl glycine sodium salt:
Among the anionic sulfonates, C18 to C56 alkaryl sulfonic acid salts are important. Higher alkyl derivatives of benzene, toluene and xylene sulfonic acids are preferred where the alkyl moiety is at least C12, preferably C,2 to Cso, more preferably C14 to C36 and especially C15 to C30. Among other aromatic sulfonates, alkyl derivatives of naphthalene sulfonic acid, tetrahydronaphthalene sulfonic acid, and diphenyl ether sulfonic acid are preferred. The alkyl substituents of aromatic sulfonic acids can be substituted by substituted alkyl group such as alkyloxy and alkylthio.The aromatic group can be also polyethoxylated. Disulfonated aromatics and petroleum sulfonates are other classes of interest.
Sulfonate surfactants can be also aliphatic such as alkane sulfonates, which can be ,B-alkoxylated, hydroxyalkane sulfonates and alkene sulfonates. These sulfonates are C12 to C60, preferably C16 to C40, in the aliphatic hydrocarbon groups Substituted aliphatic sulfonates include sulfonate derivatives of ethoxylated alkyl phenols derived from the corresponding ethoxylated sulfates. Another group of substituted sulfonates are represented by dialkyl sulfosuccinates derived from dialkyl maleates via the addition of sodium hydrogen sulfite.Further distinct classes of substituted sulfonates are those of Nacyl N-alkyl taurates preferably derived from N-methyl or N-cyclohexyl taurate and a fatty acid chloride, and sulfoethyl esters of fatty acids derived from sodium isothiorate and a fatty acid chloride,
including analogous higher alkylated sulfoethyl esters
m=1-30, n=12-30.
Surfactant sulfates include C12 to C40 aliphatic sulfates. Alkyl sulfates such as lauryl and tallow sulfate represent the most common subgroup of this class derived from the corresponding alcohols.
Unsaturated carboxylic acids and their esters, such as fats and oils, can be also sulfated via sulfuric acid addition to their olefinic groups and as such, provide another type of sulfated surfactants.
Hydroxyethyl amides of C12 to C40 fatty acids can be also sulfated to yield members of the sulfated alkanolamide class. More important, ethoxylated higher alcohols and alkyiphenols are sulfated to yield very important classes of ethoxylated sulfates. These ethoxylated intermediates can be propoxylated before sulfation. The starting alcohols of anionic sulfate surfactants are preferably in the C12 to C36 range. The alkyl groups of the alkyl-phenols-cresols and xylenols range from C12 to C60, e.g., CmH2m+1(OCH2CH2)xOSO3Na
m=C 12-C40, x=0--30, k=1 2-60.
Partial C12-C40 esters of the various phosphorus acids particularly of orthophosphoric, polyphosphoric and phosphoric acids represent another broad class of anionic surfactants. Exemplary products of simple alcohols are diethylhexyl phosphate and polyphosphate. The phosphates are preferably employed as a mixture of mono- and diesters, e.g.,
x=0--30; m=12-40 Such phosphate derivatives of dodecyl and octadecyl alcohols and their ethoxylated and propoxylated derivatives are other exemplary anionics of this type. Phosphate derivatives of ethoxylated alkyl phenols such as dodecylphenol and dinonylphenol are also included, e.g.,
Higher alkyl phenolates, such as octadecyl phenolate and dodecyl naphtholate are also regarded as anionic components.
Certain amphoteric compounds having a combination of weakly basic and strongly acidic groups can be also used as anionic surfactant components. Exemplary types of such
n=1 2-30 Comicellization forming combined surfactants also occurs with amphoteric compounds in general, e.g., CnH2n+1+N(CH3)2CHzCH2CH2SO3 ; n=12-30 Suitable cationic components are surfactant bases and their salts. In the present discussion, surfactant bases will be usually considered, although it is understood that they can be employed in the salt form. Quaternary salts, however, will be discussed as such since they are usually unstable and not available as free bases. Among the cationic surfactants, ammonium salts, phosphonium salts and quaternary ammonium salts are preferred.
The most important class of cationic surfactants are higher aliphatic amines. The carbon range of the aliphatic groups is 12 to 40, preferably 1 3 to 30. The amines can be primary, secondary and tertiary. The tertiary amines, of course, may contain 1 to 3 higher alkyl groups. In the case of the higher monoalkyl amines, the C16 to C30 alkyl range is most preferred.
A preferred class of aliphatic amines has open chain substituents such as straight chain saturated alkyl radicals. Examples are lauryl and stearyl amine. They can also be branched alkyl groups, preferably cr,cr-dimethyl alkyl groups such as those in Primenes and cr and p-substituted alkyl groups wherein the cz- and p-substitute is a C4 to C12 straight chain alkyl group. Typical straight chain unsaturated amines are the fatty amines, e.g., tallow, oleyl and soya amines. Aliphatic amines can also have isocyclic structures such as the rosin amines, e.g., dehydroabietyl amine and they can be benzylic such as octadecylbenzylamine.
A particularly preferred cationic amine is derived via the ethoxylation (and/or propoxylation) of cationic primary and secondary amines such as octadecyl amine, rosin amine, cx,cz-dimethyloctadecyl amine, dilauryl amine, alkyl pyridine, alkyl morpholine with from 2 to 30 moles of ethylene oxide.
Except for the cz,cz-disubstituted compounds, primary amines are ethoxylated involving both amine hydrogen atoms to provide the types of cationic surfactants exemplified by the following:
Another preferred group of cationic amines is represented by C12 to C40 diamines and triamines derived from primary amines via cyanoethylation and reductive amination sequences. These types of compounds are derived from fatty amines. Examples of diamines derived from fatty amines are sold under the Tradename Duomeens manufactured by Armak Co.They also can be used in the form of their ethoxylated derivatives,e.g.,
Among the fatty diamines and triamines are cyclic compounds, particularly imidazolines, derived by the reaction of fatty acid salts with hydroxy-ethyl ethylene diamine and diethylene triamine, respectively, e.g.,
These cationic imidazolines can be also advantageously ethoxylated. Amines can also possess polypropylene oxide blocks as oleophilic units. A preferred cationic component of this type is available under the Tradename of Poloxamine manufactured by BASF Wyandotte:
where the molecular weight ranges from 300 to 2000 and the weight ratio of ethylene oxide units in the oligomer ranges from 10 to 80%.
Surfactant amides, especially ethoxylated fatty amides may also serve as weakly basic cationic components, e.g.,
n=12-30;x=1 to 25 R=H, CH3 The second most important class of cationic surfactants are higher aliphatic derivatives of quaternary ammonium salts. The quaternary salts are usually derived from the corresponding cationic amines cited above. The agents for quaternization include methyl chloride, dimethyl sulfate, diethyl sulfonate, alkyl tosylates, ethylene chlorohydrin and benzyl chloride, particularly methyl chloride.
The preferred quaternary compounds are fatty amine, fatty diamine, rosine amine derivatives, especially the quaternaries based on ethoxylated derivatives of these amines. Ethoxylated alkyl pyridinium halides are another preferred type of cationic components.
Quaternary phosphorium salts having 1 to 4 C12 to C40 aliphatic groups represent another important class of cationic surfactants. These phosphorium salts include compounds having structures analogous to the discussed ammonium salts. The preferred quaternary phosphorium compounds also include phenyl substituted derivatives. Tetraalkyl phosphorium cation species are described in U.S.
patents 3,929,849 and 3,998,754 (A. A. Oswald).
In a manner similar to the quaternary ammonium components, a particularly preferred'class of phosphorium components possesses oxyethyl or oxypropyl units (x=1--30).
Less common cationic surfactants include weakly basic surfactant and surfactant precursors such as amine oxides, phosphine oxides and sulfoxides and their ethoxylated and propoxylated derivatives, examples of which are:
Amphoteric compounds having a combination of acidic and basic groups can be also used.
Exemplary types of such compounds are the following:
Nonionic surfactants are ethoxylated derivatives of phenols, amines, carboxylic acids, alcohols, mercaptans and polyhydroxy compounds. Ethoxylated C12 to C40 alcohols and alkylphenols are preferred. The ethoxylated phenols have the formula: (CnH2n+1)mA[O(CH2CH2O)p]qH where n is from 1 to 30; A is benzene, naphthalene or diphenyl; p is 2 to 30; q is 1 or 2 and m is from 1 to 5 with the proviso that there is at least one C12 to C30 alkyl chain.
Combined anionic-cationic surfactants of balanced hydrophilic-lipophilic character may be composed of the surfactant ions of the above-defined anionic-cationic and amphoteric surfactants.
Their balance is preferably assured by an appropriate degree of ethoxylation. A preferred surfactant system relates to anionic, and cationic surfactants which may be combined to produce balanced biamphiphilic anionic-cationic salt compositions. Ethoxylated alkyl ammonium sulfonates of the formula
where R is phenyl, tolyl or xylyl; R'=H or CH3; n is 12 to 40; m is 12 to 36 and x+y is from 2 to 30 are preferred.
The present liquid crystals are stabilized by higher alkyl lipophilic moieties of the surfactants. In the case of olefin, alcohol and alkyl benzene derivatives, these lipophilic moieties are at least C12 on the average. The optimum alkyl chain length, however, is generally higher for the surfactant constituents of liquid crystals as compared to microemulsions.
If one considers the higher alkyl moiety of surfactants generally, lower ranges favor the formation of microemulsions only, higher ranges liquid crystals only, and both liquid crystals and microemulsions can be formulated from intermediate ranges. The precise values are, of course, dependent on the surfactant system in question. Balanced combined quaternary ammonium sulfonate surfactants of the formula:
are an example wherein such a dependence was observed on the higher alkyl substituent of the xylene sulfonate moiety. The combined ammonium i-nonyl xylene sulfonate formed only balanced microemulsions when mixed with about one volume of n-decane per thirteen volumes Tar Springs Brine. The corresponding dodecyl derivative provided both microemulsions and liquid crystals. Finally, the i-octadecyl xylene sulfonate formed only liquid crystals.It is noted that if one relies on unaided visual observations as is commonly done in the prior art, an oil-water based liquid crystal can easily be mistaken for a "microemulsion." The formation and stability of liquid crystals are dependent on structural parameters. Unlike most micellar systems, the present lyotropic liquid crystals are largely functions of the molecular packing of surfactants, and therefore, minor structural changes will strongly influence stability. For example, ortho-substituted alkyl benzene sulfonates, such as alkyl xylene sulfonates, are preferred. In the case of anionic sulfinates, it is also preferred to have branched rather than straight chain monoalkyl groups.
Other phenomena which influence liquid crystal formation and stability include hydrogen bonding and an appropriate hydrophilic-lipophilic balance (HLB) of the surfactant components. Systems in which hydrogen bonding is possible, e.g., ethoxylated ammonium segments terminated by a hydroxy group, possess a much higher tendency to form liquid crystals over systems in which hydrogen bonding is not possible. Furthermore, liquid crystal compositions are stabilized by the balanced character for the surfactants and the preferred means for achieving this is surfactant ethoxylation.
Ethoxylated surfactants are also preferred from the viewpoint of salt tolerance of the liquid crystal compositions. An increasing number of ethoxy groups in a surfactant molecule is known to increase both the hydrophilic character and the salt tolerance of the surfactant. According to the present invention, surfactant based lyotropic liquid crystals are increasingly stabilized in high brine containing media with the increased ethoxylation of the surfactant. The brine stability of liquid crystals, however, does not increase indefinitely with the increasing ethoxylation of the surfactant. An optimum of stability is reached then a sudden decrease is observed. In general, the optimum range of average ethoxylation for any given composition is within 6, preferably within 3, most preferably within 2 ethoxy units.The average ethoxylation is below that of the corresponding microemulsions.
Most primary technical ethoxylated surfactant products have a Poisson distribution of the number of ethoxy units due to the epoxide ring opening involved in their synthesis. These primary products of varying average ethoxylation are often mixed to produce a desired average ethoxylation for certain applications. Of course, such mixing of two ethoxylated surfactants results in a wider molecular weight distribution of bimodal character. In some use areas, mixtures of surfactants of widely different ethoxylation are desirable. However, for the synthesis of the present liquid crystals of increased stability, a narrow molecular weight distribution is desired. If two components of different ethoxylation are mixed, it is preferred that their degrees of ethoxylation should differ by less than 10, more preferably less than 5, most preferably less than 2.As a rule, mixing of different ethoxylation surfactants is recommended only for an exact control of average ethoxylation where desired. Whenever economical, surfactant components having a single ethoxylation value are preferred. Beyond liquid crystal stability, this is also advantageous for reducing selective adsorption since adsorption is also reduced by increased ethoxylation.
Largely for economic reasons, the application of surfactant mixtures is sometimes desired. For example, as far as anionic surfactants are concerned, the mixing of inexpensive petroleum sulfonate salts with ethoxylated surfactants can be advantageous. It is surprisingly found that such mixtures with petroleum sulfonates, e.g., ethoxylated sulfonates, sulfates and phosphates, are stabilized when present in the liquid crystals of this invention.
A preferred class of liquid crystals has surfactants containing moieties having direct and indirect temperature-solubility relationships in a balanced proportion. For example, such surfactants have appropriate segments of alkyl groups whose solubility increases with temperature and polyethylene oxide segments which become less soluble with increasing temperatures. The solubility of surfactants optimized in this manner does not change significantly in a broad temperature range. This characteristic stabilizes the temperature stability of the present lyotropic liquid crystals and consequently extends their application to varying oil fields of increasing temperature.
With respect to the chemically enhanced displacement of oil, the techniques for secondary or tertiary recovery conventionally employed with microemulsions are applicable to liquid crystals. A typical procedure includes the injection of a liquid crystal slug followed by a pusher slug and a slug of unthickened water. The pusher slug is usually a thickened brine so as to eliminate fingering effects. Any of the conventional thickening agents may be use to provide viscosity control. Examples include polysaccharides and biopolymers such as xanthan polymers, partially hydrolyzed polyacrylamides, fatty acid soaps, alginates, amines, glycerine and the like.
The amount of liquid crystal injected is that effective to displace oil from the oil-bearing formation. Generally, from 0.01 to 1.0 pore volume based on the pore volume of the formation is sufficient.
The brine used in the liquid crystal and/or pusher is preferably similar to that found in the formation.
The liquid crystals may contain as optional additives, co-surfactants and/or co-solvents. Preferred co-surfactants and co-solvents include alcohols, ethoxylated-, sulfated ethoxylated- and sulfonated ethoxylated alcohols, all of which are C3 to C20 in the aliphatic chain as well as ethoxylated-, sulfated ethoxylated- and sulfonated ethoxylated alkyl phenols.
The additional components can also include alcohol solubilizers and consurfactants, such as butanol, i-hexanols; sulfonate hydrotropes such as xylene sulfonate salts, poly-acid salt chelating agents such as the sodium salt of triscarboxymethyl phosphine, polymers such as branched polyethylene oxide, polysaccharide biopolymers, polymeric sulfonates. Unexpectedly, unlike most known microemulsions, the present liquid crystals do not require cosurfactants.
The present liquid crystals can be employed as a homogeneous fluid or in an admixture with either isotropic brine or microemulsion. Such mixtures are generally emulsion stabilized by the liquid crystal component. They are often formed directly from the liquid crystal components in one step. Both homogeneous liquid crystals and liquid crystal-brine mixtures can be employed for oil recovery.
The liquid crystalline displacement fluids of the present invention can be employed via conventional oil recovery techniques, particularly those developed for employing microemulsions.
For further details on oil recovery techniques using microemulsions, reference is made to R. W.
Healy and R. L. Reed, Society of Petroleum Engineers,17,129 (1977) and the papers cited therein.
In spite of the relatively high viscosity exhibited by liquid crystals, it has been discovered that their use in oil recovery results in a more complete recovery at a faster rate as compared to similar microemulsions. This is in contrast to the general view of the art that high viscosity is a disadvantage in terms chemically enhanced oil recovery. In fact, typical prior art microemulsions have very low viscosities and require thickeners so as to avoid fingering effects. In addition, liquid crystals are usually found to be more stable to dilution by brine than microemulsions.
The method of the invention is further illustrated by the following examples.
Examples General Test Procedures Oil recoveries are determined by conventional sand pack tests. The sand used is a crushed Berea sandstone of 40 to 100 mesh size. Oil displacement measurements are determined from a glass burette having a 15 mm diameter, a total volume of 100 ml and calibrated at 0.1 ml intervals.
Filter paper is positioned in the bottom of the burette and the burette rotated while 75 g of sand is slowly added over a period of about 1 5 minutes. Thereafter, a filter paper and a magnetic stirrer are placed on top of the sand. The total weight of sand is checked and its volume (~46 ml) determined.
Air is purged from the burette by carbon dioxide for 30 minutes. The column is then flooded from the bottom with 40 ml brine at a rate of about 20 ml per hour. The brine used in the examples is Tar Springs Brine (TSB), characteristic of the Loudon oil field. TSB contains about 10 wt./vol. % of mixed salts with a 9 to 1 mono- to divalent metal salt ratio. The composition of the salts in grams/liter is as follows: NaCI-92.07; CaCI2-7.89; MgCI2-4.93; Back2. 2H,O--0.113; NaHCOS0.195.
The brine is injected into the column with a Sage Syringe Pump, Model 355, having 50 ml syringes. The 20 ml per hour delivery is provided at the 1/1 00x 50% setting from the syringe through a 1/8 inch Teflon tubing fitted to the bottom of the column. After the brine flooding, the supernatant aqueous phase is removed and the column weighed to determine the pore volume by difference. The pore volume is usually about 18 ml.
Thereafter, the column is again flooded, this time with 35 ml oil (Loudon crude) at the same rate.
The volume of the top oil layer is measured to determine the volume of the resident oil by difference.
The resident oil is usually about 10 ml.
The final step of preparing the sand pack for testing is flooding with 40 ml brine again at the same rate. The volume of oil removed is then determined and the residual oil saturation calculated. Its value is usually about 4 ml. The excess liquids are then syphoned off from above the sand and the sand pack column is ready for oil recovery testing.
The prepared test column is flooded from the bottom with 40 ml of the displacement medium at a rate of 2 ml per hour. This rate is provided by a 1/1 000x40% setting. The total volume out, volume of oil produced and the position of the advancing oil front are observed. The time of breakthrough for the aqueous media and the appearance of liquid crystals below the oil are also noted. The main results of the experiments are shown in the examples by appropriate figures wherein the fraction of pore volume liquid produced versus the percentage oil recovery are plotted.
Example 1 This example illustrates the improved oilwrecovery by a liquid crystal composition versus a microemulsion, wherein the active component of both, i.e., the surfactant, is a combined anioniccationic surfactant The combined surfactants are quaternary ammonium sulfonates having slightly varying degrees of ethoxylation and are described in the following formula:
x+y=7, 7.5 The combined surfactants are prepared by mixing stoichiometric amounts of the sodium salt of the sulfonic acid with the ethoxylated quaternary ammonium chloride.
Two liquid crystals (1c) and one microemulsion (me) based on the above-described surfactant systems are prepared. The first 1 c composition contains 12 wt. parts combined surfactant (x+y=7.5 prepared by combining x+y=5 and x+y=1 0 products) in a 50/50 mixture of Tar Springs Brine (TSB) and Distilled Loudon Crude Oil (Oil). This composition was prepared by adding 4% of the combined surfactant to the mixture of TSB and Oil. The resulting emulsions was then centrifuged at 25,000 G for four hours. As a result, the 1 c composition separated as a birefringent middle phase. This 1 c composition had a lamellar structure according to X-ray diffraction studies.The repeat layer distance was 68A. Its apparent Brookfield viscosity is 80 cP at a shear rate of 1.6 sec-l. It is shear thinning, i.e., non-Newtonian in character, as lamellar liquid crystals generally are.
The second 1 c composition was produced by adding 3 wt. parts of a similar surfactant having a slightly lower degree of ethoxylation (x+y=7) to 100 parts of a TSB, n-decane mixture having a 93 to 7 volume ratio. This 1 c had a lower Brookfield viscosity (30 cP at 1.6 sec-1) but was also non-Newtonian in character at low shear rates.
The third composition was a microemulsion produced by 2 parts per 100 of the surfactant of the first 1 c when using a 93 to 7 TSB to n-decane ratio. This me had a very low apparent viscosity, 3.6 cP at 7.3 such'.
The oil recovery results obtained using the three compositions are summarized in Figure 1 by plotting fraction of pore volume fluid injected as a function of residual oil recovered. In Figure 1, the symbois , a and 0 represent the first and second liquid crystals and the microemulsion, respectively.
In essence, these results demonstrate that the two liquid crystals displaced oil at a similar and much faster rate than the microemulsion.
The use of the first 1 c resulted in a rapid oil bank formation and front advancement. Oil production started early at 0.43 pore volume (PV) and continued at a rapid, steady rate until 79% of the oil was recovered at 0.77 PV. Thereafter, 11 ml of a separate brownish liquid crystal layer was produced. In volume, this is double of that of the residual oil. This layer apparently contained significant quantities of Loudon Crude (LC) Oil in addition to the distilled Loudon Crude (DLC) Oil. The brine phase remained clear and transparent during this secondary oil production. The brine turbulence, usually characteristic of microemulsion breakthrough, occurred only thereafter at 1.34 PV. Indications were for complete LC oil plus DLC oil recovery.
In the case of the second 1 c, oil production also started early (0.41 PV) and occurred at a fast, steady rate. LC oil pick-up by this liquid crystal was less. About 87% of the LC oil was produced as the first separate layer at 0.79 PV. Therafter, again a liquid crystal layer was produced.
The comparative experiment with the me composition also resulted in a complete oil recovery but at a much slower rate. Oil production started at 0.76 PV. Breakthrough occurred when 86% of the oil was recovered at 1.46 PV. The total apparent oil production was 104%.
Example 2 The effect on oil recovery by liquid crystals based on the different structure of the combined surfactants is described in this example. The surfactants are set forth as follows:
I: n=12 R=H x+y=6 (5+7) II: P n=18 R=CH3 x+y=9.3 (9+10) The compositions of the liquid crystals are summarized in the following table.
Table I Composition Viscosity No. Symbol TSB Oil Suff cP (7.3 such') I A 92 8 2.4 18 II 0 93 7 3 11 The surfactant is expressed in wt parts per 100 parts of TSB/oil mixture in which the oil is ndecane. The amounts of TSB and oil are parts by volume. It is noted that the average degrees of ethoxylation for the two surfactants were selected to control their hydrophilic-lipophilic balance so as to provide liquid crystals of high brine to hydrocarbon ratio. The surfactant concentrations were close to the minimum needed to produce liquid crystals. Both liquid crystals had a non-Newtonian shear thinning character and comparable apparent viscosities.
The oil recovery results obtained from the two different liquid crystals as a function of pore volume injected vs. oil recovered are shown in Figure 2 in which the oil recovery from 1 c (I) is designated by and 1 c (II) by A. These results indicate that both liquid crystals produced oil early and at a fast rate, and are very similar to the results obtained from the liquid crystals of Figure 1.
In the case of the i-dodecyl benzene sulfonate based combined surfactant (I), breakthrough occurred after 83% of the oil was recovered at 0.79 PV. At higher pore volumes, most of the oil was produced in a mixture with the displacement fluid as a liquid crystal. By the time 1.17 PV fluid was injected, 8.6 ml diluted liquid crystal layer accumulated below the recovered oil (3.6 ml, 86%). On centrifugation, 0.3 ml (7%) additional oil separated from this liquid crystal composition. Including this, the amount of the total oil recovery was 93%.
When using the i-octadecyl-o-xylene sulfonate based combined surfactant (II), breakthrough occurred after recovering 90% of the oil at 0.84 PV. The overall oil recovery behavior of this liquid crystal was similar to that of the previous composition. At high brine concentrations, this combined surfactant, unlike those described previously, has a tendency to form 1 c rather than me compositions.
Example 3 This example is directed to the effect of different hydrocarbons on liquid crystal compositions containing the same combined surfactant and brine. The hydrocarbons are n-decane (D) and distilled Loudon Crude Oil (DLC). The combined surfactant is described by the following formula and Table:
n-Decane(D) x+y=8
Distilled Loudon x+y=9.1(5+lO) Crude Oil (O) Y Table II Composition Viscosity, cP Hydrocarbon (sec1) No.Symbol Type TSB Suff (1.6) (8) D z D 7 93 2 - 10 II A D 9.5 90.5 3.8 100 48 Ill I DLC 10 90 3.8 114 56 The surfactant concentration is in parts by weight per 100 parts of hydrocarbon/TSB mixture expressed in parts by volume.
It is noted that to achieve the required hydrophilic-lipophilic balance, the use of a more highly ethoxylated combined surfactant was necessary in the oil than in the decane mixtures. It should be also observed with regard to the two decane systems that the system containing a higher concentration of the surfactant had a higher hydrocarbon content. The decane system of lower surfactant concentration was of lower viscosity as expected. However, both systems exhibited non-Newtonian rheology in the shear rate region studied (1.6-1 6 sec-1).
As is shown by Figure 3, the oil recovery behaviour of the three systems was very similar The rate of oil production characterized by the overall slope of the injection-recovery correlation was practically identical for the two mixtures of higher surfactant concentration.
In the case of the two decane systems, the one with more surfactant started producing oil earlier.
However, both systems produced oil almost at the same rate and continued to produce oil in the form of liquid crystal after breakthrough.
Interestingly, the distilled Loudon crude oil based system required more surfactant to produce liquid crystal organization. However, this oil system of relatively high surfactant content in most respects behaved like the decane system of low surfactant content. It took the longest time to produce oil and breakthrough occurred after a relatively small oil recovery. However, recovery in the form of liquid crystals continued. It was estimated on the basis of centrifugal separation that at 1.36 PV, the total oil recovery was 93%.
Example 4 The comparison of liquid crystals versus microemulsions wherein the surfactant system is based on a mixture of anionic surfactants is demonstrated by this example. One liquid crystal and one microemulsion were prepared with the same mixture of two anionic sulfonate surfactants. The first surfactant was a petroleum sulfonate sodium salt of 465 average molecular weight, Petrostep 465, manufactured by Stepan Chemical Co. The second was the sodium sulfonate derivative of an ethoxylated n-alcohol, EOR 200 manufactured by Ethyl Corp. As such, the first surfactant was lipophilic: the second, hydrophilic in character. An appropriate mixture was used to provide the hydrophilic-lipophilic balance required.
The composition of the Petrostep 465 was 57.8% active sulfonate, 15.5% water, 2.7% inorganic salts mainly sodium sulfate and 24% non-sulfonated petroleum hydrocarbon. The latter provided the oil component of the liquid crystal. The technical ethoxylated sulfonate had an active content of 29.3% total solids of 49% and 2% "oil".
Interestingly, the 1 c and me compositions were prepared using the same concentration of the same surfactant mixture plus pentanol: 3% Petrostep 465 (1.7% active), 7% EOR-200 (2% active), 2% pentanol. When 5% aqueous sodium chloride was used to make up the rest (88%), the liquid crystal formed. When 2% aq. NaCI was employed instead, a microemulsion having a viscosity of 16 cP at 8 such' was produced. The Brookfield viscosities were 20 cP and 16 cP, respectively, at a shear rate of 8 sec-'.
The liquid crystal had a non-Newtonian, i.e., shear thinning, viscosity character. However, its viscosity increased as shearing continued as indicated by the following results of repeated Brookfield viscosity determinations: Table III Apparent Viscosity, cP at Various (Stirring Rates, rpmJ Shear Rates, Sec-' Sequence of (62 (12) {30J (60) Viscosity Test 1.6 3.2 8 16 1 28 20 20 21 2 60 62 46 30 3 103 89 55 32 The microemulsion was less viscous and of a simple shear thinning behaviour. At the 7.3 sec-l shear rate, this mixture had an apparent viscosity of 1 6 cP.
The oil recovery behaviour for the liquid crystal (A) and microemulsion (A) is shown in Figure 4.
This figure demonstrates the much superior behaviour of the liquid crystal (ic) versus that of the microemulsion (me).
The use of the 5% NaCI aq. 1 c mixture, resulted in an early oil production at a fast rate. By the time of the breakthrough at 1.07 PV, 94% of the oil was recovered. At 1.11 PV, complete recovery was observed. Thereafter, the formation of a second liquid crystalline phase was observed between the recovered oil and displaced brine layer. The eventual oil production was more than 100%, apparently due to the oil introduced as a component of the liquid crystal composition.
In contrast, the application of the 2% NaCI mixture resulted in a comparatively delayed incomplete oil production. Oil production started at 0.73 PV. After recovering only about 26% of the oil, breakthrough has occurred at 1 PV. The total recovery was about 82% after 1.56 PV.
Example 5 This example illustrates some properties of microemuisions versus liquid crystals based on combined ammonium sulfate surfactants. Ammoniate surfactants such as combined anioniccationic surfactants of balanced hydrophilic-lipophilic character by definition will provide a middle phase containing equal volumes of oil and water (brine) and/or will reject equal amounts of oil and water (brine) when mixed in proper amounts with equal volumes of oil. Such middle phases can have a multiple phase character and a liquid crystalline, liquid crystalline plus isotropic microemulsion or isotropic microemulsion only character as exemplified by the following.
Approximately balanced middle phases were obtained using three combined quaternary ammonium sulfonate surfactants prepared from the corresponding methyl esters of sulfonic acids. The esters are described in copending U.S. Application Serial No. 935,610 by A. A. Oswald and E. J.
Moxeleski. The combined quaternary sulfonates were prepared by reacting the ester with the appropriate ethoxylated amines. The structures of the three surfactants used are shown in Table IV.
The other components of the mixtures were 0.4 q (~4%) surfactant, 5 ml (~48%) distilled Loudon crude oil and 5 ml (~48%) of brine of varying salt concentration. Homogeneous mixtures were prepared by Vortex stirring for about 1 5 minutes. The mixtures were then centrifuged at 250C for a total of three hours at 27,000G. To obtain stable three phase systems: Oil phase on the top, "microemulsion" middle phases and brine on the bottom. After the centrifugation, the phase volumes were determined and the middle phases were studied for visual appearance and birefringence. Middle phase samples were also investigated using polarizing and phase contrast microscopy. The observations are summerized in Table IV.
With regard to phase distribution and salt insensitivity, the results are described as follows. The volumes of the rejected oil and brine phases were generally comparable and surprisingly independent of the salt concentrations. Surprisingly, the investigation of the middle phases demonstrated that in the majority of cases, they contained anisotropic liquid crystals in isotropic fluid. It was particularly surprising that at high brine concentrations, liquid crystal formation appeared to be enhanced. The presence of oil apparently stabilized the liquid crystals.
The first combined surfactant, a pure one component compound (A), produced typical middle phase microemulsions at most brine concentrations. Significant liquid crystal middle phase formation occurred only when Tar Springs Brine (TSB) containing 10% of mixed salts including about 9.2% NaCI, 0.8% CaCI2 and 0.5% CaCI2 was used.
The second combined surfactant (B), a quaternary analog of a combined surfactant having an average degree of ethoxylation, produced birefringent liquid crystal middle phases at all salt concentrations. To the naked eye, most of these middle phases appeared to be typical translucent microemulsions. However, under the microscope, it became clear that they had larger droplet sizes.
The anisotropic liquid crystals separated from brine mixtures of different concentrations were microscopically different as illustrated by the pictures of Figure 5. Most often liquid crystal droplets of various size (in the 16 y region) were observed as found in 10% TSB (Pictures A-1 and A-2). At 5% NaCI concentration, one of the liquid crystal phases appeared definitely lamellar in character (Pictures B-1 and B-2). Finally, at 2% salt concentration, typical flow birefringence was observed (Picture C).
The third combined surfactant (C) of Table IV based on an ethoxylated ether amine, produced liquid crystalline phases similar to the Ethomeen derivative (B). Again the translucent liquid crystals had the typical microemulsion appearance.
The behaviour of eight centrifuged three phase systems based on the two hydroxyl terminated ethoxylated amine derivatives (B and C) were studied at various temperatures to determine the stability of the liquid crystal phases. Observations at 35, 50 and 700C showed that the anisotropic liquid crystal character of the middle phases was maintained, although the phase distributions changed somewhat.
Beyond the above microscope studies, the structure of liquid crystals could be also diagnostically characterized by nuclear magnetic resonance (nmr). Nmr indicated special structural interactions increasing the relaxation times of nuclei. Investigations of the above middle phases and other liquid crystal mixtures showed that the viscosity of such liquid crystals is not necessarily too high and their interfacial tension is at a minimum. Therefore, liquid crystals possess oil displacement properties attractive for oil recovery.
Table IV Combined Ammonium Sulfonate Surfactants as Microemulsifiers (in 4% Oil, 48% Distilled London Crude Oil and 48% Brine) of Varying Salt Concentration
A. One Component Capped Derivative
B. Ethomeen Derivative; x+y=7.5
C. Ether Amine Derivative; x+y=7.5. Table IV (continued) Observations After 3 Hours Centrifugation at 25 C and Salt Phase Distribution, % Appearance of Middle Phases (l.: birefringent liquid crystal; me.: isotropic microemulsion Middle No. Surfactants Type Conc.% Oil Phases Brine Top Middle Bottom I A TSB 10 28 51 51 21 4% Emulsion 48% Translucent me. 48% Hazy Ic.
II 5 17 56 27 16% Emulsion 36% Hazy me. 48% Clear me.
III NaCl 5 19 52 29 13% Emulsion 61% Hazy me. 26% Clear me.
IV 2 20 51 29 29% Emulsion - 71% Hazy me.
II B TSB 10 36 30 34 None 100% Translucent Ic. None III 5 25 51 24 23% Hazy Ic. 19+46% Translucent Ic. 12% Emulsion IV NaCl 5 26 48 26 4% Translucent Ic. 32% Hazy Ic. 63% Translucent Ic.
V 2 24 52 24 8% Hazy Ic. 77% Translucent Ic. 15% Emulsion III C TSB 10 34 32 34 19% Emulsion 69% Translucent Ic. 12% Emulsion IV 5 34 48 28 16% Emulsion 59+21% Hazu Ic. 4% Emulsion V NaCl 5 36 37 27 26% Translucent Ic. - 74% Hazy Ic.
VI 2 36 38 28 47% Translucent me. 48% Hazy Ic. 5% Emulsion Example 6 Oil recovery by liquid crystals was also examined using a number of different types of surfactants and their mixtures exemplified as follows. A translucent, flow birefringent mixture based on a 2.1% sodium i-dodecyl-o-xylene sulfonate (88% active) and 1.9% Igepal DM-730 from GAF Corp. (a tetradocosa-ethoxylated dinonyl phenol) produced a similar high and early oil recovery to the liquid crystal compositions described above. This shows that mixtures of sulfonates, particularly alkylbenzene sulfonates, and ethoxylated higher alkyl phenols, particularly higher dialkyl substituted phenols are attractive surfactant mixtures for obtaining liquid crystalline compositions for oil recovery. As is generally the case, such mixtures could be used with or without polymers.
A liquid crystalline mixture of 4% Petrostep 465 and 2% Siponic L-7 which is an ethoxylated lauryl alcohol manufactured by Alcolac, Inc., also produced excellent oil recovery results.

Claims (36)

Claims
1. A process for recovering oil from an oil-bearing formation in the presence of highly concentrated brine which comprises displacing oil with a primary displacement fluid containing lamellar liquid crystals which exhibit decreasing viscosities at increasing shear rates and comprise (a) 0.5 to 10 vol.% of a surfactant, (b) 0.1 to 20 vol.% of an oil and (c) brine containing from 5 to 30 wt.% of inorganic salts comprising sodium chloride and salts of divalent metals, driving the liquid through the formation and recovering the displaced oil.
2. A process according to claim 1 wherein the surfactant is a balanced surfactant.
3. A process for recovering oil from an oil-bearing formation by injecting into the formation a liquid to displace oil, driving the liquid through the formation and recovering the displaced oil, wherein the liquid comprises a lamellar liquid crystal which exhibits decreasing viscosities at increasing shear rates and contains (a) 0.5 to 10 vol.% of surfactant of balanced hydrophilic-lipophilic character, (b) 0.1 to 20 vol.% of an oil, and (c) brine containing from 5 to 30 wt.% of inorganic salts comprising sodium chloride and salts of divalent metals.
4. A process according to any one of the preceding claims wherein the sodium chloride in the brine is a major proportion by weight and the salts of divalent metals are as minor proportion by weight.
5. A process according to any one of the preceding claims wherein the amount of oil is from 0.5 to 10 voi.%.
6. A process according to any one of the preceding claims wherein the inorganic salts include Ca2+ and Mg2+.
7. A process according to any one of the preceding claims wherein the oil is a distillate hydrocarbon oil.
8. A process according to any one of the preceding claims wherein the surfactant is an anionic, cationic, nonionic, amphoteric surfactant or a mixture thereof.
9. A process according to claim 8 wherein the anionic surfactant is a sulphonate, sulphate or ester of a phosphorus acid.
10. A process according to claim 8 wherein at least one surfactant component is ethoxylated.
1 A process according to claim 10 wherein the ethoxylated surfactant component is therminated by hydroxy groups.
12. A process according to either of claims 10 and 11 wherein the ethoxylated surfactant is an ethoxylated alkylphenol.
13. A process according to claim 8 wherein the surfactant is nonionic and is an ethoxylated phenol of the formula (CnH2n+1)mA(O(CH2CH2O) p)q H where n is from 1 to 30, A is benzene, naphthalene or diphenyl, p is 2 to 30, q is 1 or 2 and m is from 1 to 5 with the proviso that there is at least one C12 to C30 alkyl chain.
14. A process according to claim 10 wherein the ethoxylated surfactant component contains an alkyl substituent.
1 5. A process according to claim 14 wherein the alkyl and polyethylene oxide moieties are selected to provide temperature stable liquid crystals.
1 6. A process according to claim 10 wherein the surfactant comprises an ethoxylated sulfonate surfactant.
1 7. A process according to claim 1 6 wherein the ethoxylated sulfonate surfactant is a C15 to C30 alkylaryl sulphonate or a C16 to C40 aliphatic sulphonate.
1 8. A process according to claim 10 wherein the nonionic surfactant is an ethoxylated C12 to C40 alcohol.
1 9. A process according to claim 10 wherein the surfactant comprises ethoxylated anionic, ethoxylated cationic and ethoxylated nonionic surfactants terminated by hydroxy groups.
20. A process according to claim 9 wherein the sulphonate is C18 to C56 alkaryl or C12 to C60 aliphatic sulphonate.
21. A process according to claim 9 wherein the sulphate is a C12 to C40 aliphatic sulphate or a sulphated ethoxylated higher alcohol or alkyl phenol where the alkyl moiety of the alcohol or phenol is C12 to C36 and C,2 to C60, respectively.
22. A process according to claim 9 wherein the ester is a C12 to C40 ester of a phosphorus acid or a phosphated ethoxylated C,2 to C40 alcohol.
23. A process according to claim 8 wherein the cationic surfactant is an ethoxylated derivative of C,2 to C40 aliphatic amine, C,2 to C40 diamine or triamine, C,2 to C30 amine, C,3 to C40 quaternary aliphatic ammonium or quaternary phosphonium salt having from 1 to 4 C,2 to C40 aliphatic groups.
24. A process according to claim 23 wherein the cationic surfactant is ethoxylated with from 2 to 30 moles of ethylene oxide per mole of surfactant.
25. A process according to claim 8 wherein the surfactant component comprises a mixture of a petroleum sulphonate and ethoxylated surfactant or sulphonate surfactant and ethoxylated higher dialkyl phenol.
26. A process according to claim 8 wherein the surfactant comprises an ortho-substituted alkyl benzene sulphonate and an ethoxylated surfactant
27. A process according to claim 26 wherein the sulphonate is an alkyl xylene sulphonate.
28. A process according to any one of claims 1 to 7 wherein the surfactant is a balanced combined anionic-cationic surfactant biamphiphilic salt containing anionic, cationic or amphoteric surfactant ions.
29. A process according to any one of claims 2 to 7 wherein the surfactant is a balanced combined surfactant biamphiphilic salt composed or surfactant ions of anionic, cationic and amphoteric surfactants.
30. A process according to claim 29 wherein the combined surfactant biamphiphilic salt is composed of surfactant ions of anionic and cationic surfactants.
31. A process according to claim 29 wherein the balanced hydrophilic-lipophilic character of the combined surfactant biamphiphilic salt is achieved by'adjusting the degree of ethoxylation in a surfactant component.
32. A process according to claim 8 wherein the surfactant is a combined surfactant of the formula
wherein R is phenyl, tolyl or xylyl; R' is H or CH3; n is 12 to 40,mis 12 to 36 and x+y is 2 to 30.
33. A process according to claim 1 which comprises (a) 7 vol.% of Loudon oil; (b) 3 wt.% of a combined surfactant of the formula
where x+y=7; and (c) brine containing 10 wt.% inorganic salts including 9% sodium chloride and 1% salts of divalent metals.
34. A process according to any one of the preceding claims which includes a polymeric conventional thickening agent.
35. A process for recovering oil from an oil-bearing formation according to claim 1 substantially as hereinbefore described with reference to the Examples.
36. Oil whenever recovered from an oil-bearing formation according to any one of the preceding claims. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
GB8018869A 1979-06-11 1980-06-10 Oil displacement enhanced by lyothropic liquid crystals in highly saline media Expired GB2057533B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US4764179A 1979-06-11 1979-06-11

Publications (2)

Publication Number Publication Date
GB2057533A true GB2057533A (en) 1981-04-01
GB2057533B GB2057533B (en) 1983-04-07

Family

ID=21950107

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8018869A Expired GB2057533B (en) 1979-06-11 1980-06-10 Oil displacement enhanced by lyothropic liquid crystals in highly saline media

Country Status (4)

Country Link
CA (1) CA1136839A (en)
DE (1) DE3022336A1 (en)
FR (1) FR2458671A1 (en)
GB (1) GB2057533B (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8029772B2 (en) 2001-12-21 2011-10-04 Rhodia Inc. Stable surfactant compositions for suspending components
WO2011110601A3 (en) * 2010-03-10 2012-01-19 Basf Se Method for producing crude oil using cationic surfactants comprising a hydrophobic block having a chain length of 6 - 10 carbon atoms
GB2483024B (en) * 2009-06-12 2014-08-06 Baker Hughes Inc Liquid crystals for drilling, completion and production fluids
US8828364B2 (en) 2007-03-23 2014-09-09 Rhodia Operations Structured surfactant compositions
CN104531117A (en) * 2015-01-14 2015-04-22 中国海洋石油总公司 Non thermo-sensitive type lyotropic liquid crystal soluble oil system, preparation method thereof and application
CN114466917A (en) * 2019-09-19 2022-05-10 日本东晟株式会社 Lubricant composition and bearing sealed with same
CN116396791A (en) * 2018-07-17 2023-07-07 国立大学法人山梨大学 Lubricant composition and bearing
US20240059958A1 (en) * 2022-08-19 2024-02-22 Saudi Arabian Oil Company Reuse of hypersaline brine with ionic liquids

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3307252A1 (en) * 1983-03-02 1984-09-06 Hoechst Ag, 6230 Frankfurt METHOD FOR CONTROLLING THE MOBILITY OF SLIT, SLOT OR PORE FLOWS
DE3431414A1 (en) * 1984-08-27 1986-02-27 Hoechst Ag, 6230 Frankfurt MOBILITY CONTROL OF GAP, SLOT OR PORE FLOWS
CA3030474A1 (en) 2016-07-26 2018-02-01 Saudi Arabian Oil Company Addition of monovalent salts for improved viscosity of polymer solutions used in oil recovery applications

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3391736A (en) * 1964-03-16 1968-07-09 Mobil Oil Corp Liquid flow in a permeable earth formation
US3254714A (en) * 1965-11-05 1966-06-07 Marathon Oil Co Use of microemulsions in miscible-type oil recovery procedure
CA921690A (en) * 1968-03-11 1973-02-27 L. Murphy Charles Flooding method for the recovery of oil from a subterranean formation
US3928215A (en) * 1973-06-29 1975-12-23 Marathon Oil Co High fluidity cutting oils which exhibit retro-viscous properties
US4059154A (en) * 1973-12-03 1977-11-22 Texaco Inc. Micellar dispersions with tolerance for extreme water hardness for use in petroleum recovery
GB1441710A (en) * 1974-05-08 1976-07-07 Texaco Development Corp Oil recovery process
GB1504789A (en) * 1975-12-02 1978-03-22 British Petroleum Co Hydrocarbon/water mixtures

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8029772B2 (en) 2001-12-21 2011-10-04 Rhodia Inc. Stable surfactant compositions for suspending components
US8828364B2 (en) 2007-03-23 2014-09-09 Rhodia Operations Structured surfactant compositions
GB2483024B (en) * 2009-06-12 2014-08-06 Baker Hughes Inc Liquid crystals for drilling, completion and production fluids
WO2011110601A3 (en) * 2010-03-10 2012-01-19 Basf Se Method for producing crude oil using cationic surfactants comprising a hydrophobic block having a chain length of 6 - 10 carbon atoms
CN104531117A (en) * 2015-01-14 2015-04-22 中国海洋石油总公司 Non thermo-sensitive type lyotropic liquid crystal soluble oil system, preparation method thereof and application
CN116396791A (en) * 2018-07-17 2023-07-07 国立大学法人山梨大学 Lubricant composition and bearing
CN114466917A (en) * 2019-09-19 2022-05-10 日本东晟株式会社 Lubricant composition and bearing sealed with same
US20240059958A1 (en) * 2022-08-19 2024-02-22 Saudi Arabian Oil Company Reuse of hypersaline brine with ionic liquids
US11939521B2 (en) * 2022-08-19 2024-03-26 Saudi Arabian Oil Company Reuse of hypersaline brine with ionic liquids

Also Published As

Publication number Publication date
CA1136839A (en) 1982-12-07
GB2057533B (en) 1983-04-07
FR2458671A1 (en) 1981-01-02
DE3022336A1 (en) 1980-12-18
FR2458671B1 (en) 1983-01-14

Similar Documents

Publication Publication Date Title
US4434062A (en) Oil displacement enhanced by lyotropic liquid crystals in highly saline media
US4293428A (en) Propoxylated ethoxylated surfactants and method of recovering oil therewith
US4353806A (en) Polymer-microemulsion complexes for the enhanced recovery of oil
US3275075A (en) Viscosity control in petroleum recovery
US3406754A (en) Petroleum production utilizing miscibletype and thickened slugs
US4360061A (en) Oil recovery process using polymer microemulsion complexes
US4077471A (en) Surfactant oil recovery process usable in high temperature, high salinity formations
US3954627A (en) Lamellar micelle containing compositions which exhibit retro-viscous properties
US4597879A (en) Micellar slug for oil recovery
US4544033A (en) Oil recovery process
CN103189468B (en) Alkoxycarboxylates's surfactant
CA1107049A (en) Waterflooding employing thickened aqueous liquids
US4017405A (en) Soluble oil composition
BR112020020356A2 (en) METHOD FOR MOVING A HYDROCARBONET MATERIAL IN CONTACT WITH A SOLID MATERIAL, METHOD FOR REDUCING THE VISCOSITY OF A HYDROCARBONET MATERIAL, METHOD OF TRANSPORTING A HYDROCARBONET MATERIAL THROUGH A TUBE OF A TUBE , METHOD OF CONVERSION OF AN UNFINISHED PETROLEUM ACID INTO A SURFACTANT, METHOD FOR DISPLACING A BETUMINOUS MATERIAL IN CONTACT WITH SOLID MATERIAL BITUMINOUS AND METHOD OF TRANSPORTING A BITUMINOUS MATERIAL THROUGH A PIPE
US4555351A (en) Micellar slug for oil recovery
CN102762688A (en) Process of using hard brine at high alkalinity for enhanced oil recovery (eor) applications
US4537253A (en) Micellar slug for oil recovery
EP2838878A1 (en) Short hydrophobe surfactants
EP0037699B1 (en) Polymer microemulsion complexes and their use for the enhanced recovery of oil
GB2057533A (en) Oil Displacement Enhanced by Lyothropic Liquid Crystals in Highly Saline Media
US4269271A (en) Emulsion oil recovery process usable in high temperature, high salinity formations
US3920073A (en) Miscible flooding process
CA3029400A1 (en) Composition, method and use for enhanced oil recovery
GB2138866A (en) Micellar slug for oil recovery
US4534411A (en) Micellar slug for oil recovery

Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee