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BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to the acid treatment of subterranean earth
formations, and more particularly to the acid treatment of siliceous
subterranean formations surrounding oil wells, gas wells, water injection
wells and similar boreholes.
(2) Description of the Prior Art
Acid treatment or "acidizing" is a well-known expedient employed for
rejuvenating oil-producing and gas-producing formations and to facilitate
the ease with which fluid such as water, brine or gas can be injected into
subterranean formations surrounding a wellbore. Acidizing of siliceous
formations, e.g. sandstone, shale, serpentines, etc., has met with some
favorable results when the formation is treated with hydrogen fluoride.
Various modifications of this hydrogen fluoride acidizing have been
disclosed in the prior art. These modifications have mainly consisted of
the use of various mixtures of hydrogen fluoride and various other mineral
acids such as orthophosphoric acid, fluorophosphoric acid, sulfuric acid,
hydrochloric acid, etc. Although such mixtures are generally effective,
experience has shown that many formations do not respond to the acid
treatment.
In general, hydrocarbon-bearing siliceous formations are of a heterogeneous
nature and contain a variety of inorganic materials. In addition, the
pores of the formation may contain objectional deposits of organic matter
such as viscous crude oil, waxes, asphaltenes and resin precipitates of
petroleum origin. Conventionally, before the acidizing treatment is begun
this undesirable organic matter must be removed. Solvents such as carbon
disulfide, carbon tetrachloride, or an aromatic hydrocarbon are first
injected into the formation surrounding the well. This solvent treatment
is repeated several times until the pores of the formation are relatively
free of the organic material to insure a proper acidizing environment in
the formation.
Another problem common to all methods of acidizing is the production of
precipitates within the formation interstices through the action of the
acid-treating reagent or its byproducts on some precipitate-forming
constituent of the formation. This generally occurs when the acidizing
fluid is spent and precipitates in a form which plugs the pores of the
producing formation. As noted above, acidizing techniques have previously
employed mixtures of phosphoric acid, generally referred to as
orthophosphoric acid, with other mineral acids. However, the
orthophosphates of polyvalent or heavy metals are all virtually insoluble
in water. For example, calcium and magnesium compounds are found in all
producing formations, and when attacked by phosphoric acid mixtures form
insoluble phosphates. The calcium and magnesium phosphates are especially
difficult to remove and require expensive procedures to revitalize a
producing formation. Therefore, there exists a need for a composition
which will provide a "one shot" acidizing treatment which removes
objectionable deposits of organic material, eliminating the need for a
separate solvent treatment step, along with an acidic-treating reagent
that does not form precipitates within the formation.
Accordingly, a principal object of this invention is to provide a novel
composition and method for increasing the permeability of siliceous
subterranean formations.
Another object is to provide a composition and method which remove both
acid-soluble and oil-soluble components from the formation.
A further object is to provide a composition which does not form
undesirable precipitates on reaction with the formation.
Other objects, advantages and features of the invention will become
apparent from the following description and appended claims.
SUMMARY OF THE INVENTION
The invention relates to a non-aqueous emulsion composition for increasing
the permeability of siliceous subterranean geological formations, and to a
method for acidizing which dissolves organic materials and avoids the
formation of insoluble inorganic precipitates and many of the other
difficulties encountered in prior art acidizing methods. The invention
involves the injection into the formation of a novel, non-aqueous emulsion
comprising a substantially anhydrous liquid polyphosphoric acid-based
mixture, an organic solvent composition, and a surface-active agent or
surfactant. The acid component of the emulsion comprises about 5 to 95
weight percent of a substantially anhydrous liquid polyphosphoric
acid-based mixture comprising (a) about 50 to 99 weight percent
polyphosphoric acid with about 5 to 86 weight percent of the total P.sub.2
O.sub.5 present as polymeric P.sub.2 O.sub.5, (b) about 1 to 25 weight
percent hydrofluoric acid, and (c) optionally up to 50 weight percent of a
catalyst selected from the group consisting of strong mineral acids,
carboxylic acids, oxidizing compounds, and mixtures thereof, in which the
H.sub.2 O/P.sub.2 O.sub.5 mole ratio in the overall emulsion composition
is less than 3.4. The emulsion also contains about 5 to 95 weight percent
of an organic solvent composition selected from the group consisting of
polar solvents, hydrocarbon solvents, and mixtures thereof; and about 0.01
to 3.0 weight percent of a surfactant selected from the group consisting
of cationic surfactants and nonionic surfactants.
This novel, non-aqueous emulsion composition can be utilized in both matrix
acidizing and acid fracturing well stimulation procedures, and also has
utility in many varied applications such as gas drying, extracting metals
from ores, metal treatment, removing scale deposits from steam boilers and
pipes, and particularly in methods where solvent treatment is desired
along with acidizing action.
BRIEF DESCRIPTION OF THE DRAWING
The drawing is a graph illustrating the relationship of the polymeric
P.sub.2 O.sub.5 content of the polyphosphoric acid ingredient of the
emulsion composition as a function of the mole ratio of H.sub.2 O/P.sub.2
O.sub.5.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The novel, non-aqueous acid emulsion of the present invention comprises an
acid component, an organic solvent component and a surfactant capable of
forming either an acid-in-solvent emulsion or a solvent-in-acid emulsion.
The composition of the non-aqueous polyphosphoric acid-based emulsion
employed in carrying out this invention will depend upon its ultimate use.
Compositions of non-aqueous acid emulsions comprising a mixture of about 5
to 95 weight percent of the acid component; about 5 to 95 weight percent
of the organic solvent component; and about 0.01 to 3.0 weight percent of
a anionic or nonionic surfactant are encompassed by the invention.
The non-aqueous acid emulsion compositions are prepared by: (1) adding the
surfactant to the solvent component with moderate stirring, and (2) adding
this surfactant-solvent mixture to the acid component with moderate
stirring to form the emulsion. The rate of addition of the
surfactant-solvent mixture is critical and should be slow enough so as not
to break the emulsion already formed. In an alternate method the
surfactant is added to the acid component with moderate stirring and then
the solvent component is blended into this acid mixture. The rate of
addition of components must also be controlled to avoid breaking the
emulsion. These methods provide stable emulsions which can be either
solvent external-acid internal or acid external-solvent internal. It is
generally preferred to use the solvent external-acid internal type
emulsion in treating formations. When this type of emulsion enters a
formation pore the solvent first contacts and dissolves any organic
material present, thus exposing the siliceous formation to the acid.
The general reactions involved in the attack of the substantially anhydrous
liquid polyphosphoric-based acid emulsions of this invention upon
siliceous compounds are expressed by the following equation:
##STR1##
In the first step of the reaction, a phosphosilicate complex is formed.
Under anhydrous conditions the soluble phosphosilicate complex then reacts
with hydrofluoric acid to produce a gas, silicon tetrafluoride, and to
regenerate polyphosphoric acid and water. The overall concept of this
invention is that the acid component rapidly dissolves the silica and
complexes other metals such as aluminum, iron, cobalt, nickel, copper,
zinc, and the like. Polyphosphoric acid mixtures having a mole ratio of
water to phosphorus pentoxide (H.sub.2 O/P.sub.2 O.sub.5) of between about
2.1 and 3.4, and particularly between about 2.2 and 2.8, form soluble
complexes with most cations. Furthermore, the polyphosphate complexes are
stable after neutralization. The in situ formation of gaseous silicon
tetrafluoride provides the additional benefit of sweeping and carrying
undissolved solids away from the reaction zone. The micron-sized bubbles
of gaseous silicon tetrafluoride are able to transport the undissolved
particles of debris through the formation without plugging or bridging.
Excess polyphosphoric acid is required to remove the ambient and produced
water in order to keep the system in an anhydrous condition, i.e.,
maintaining the mole ratio of water to phosphorus pentoxide in the overall
acid mixture below 3.4 and in emulsion form.
In the treatment of subterranean formations, a novel, non-aqueous emulsion
composition is injected into a well and into contact with a siliceous
subterranean formation containing a solid or semi-solid accumulation of
hydrocarbons within the formation pores. This novel, non-aqueous emulsion
composition constitutes a "one shot" treatment with the solvent component
removing the undesirable hydrocarbon accumulations from the pores of the
formation, thus preconditioning the formation for the attack of the acid
component of the emulsion. The emulsion is stable at temperatures existing
in the well but subject to being broken by either contacting the
pore-plugging hydrocarbons or reacting with the silica formation.
In accordance with this invention, the exact emulsion used will depend
largely upon the particular type of formation to be acidized. In
predominantly siliceous geological formations containing sandstone, shale
or other siliceous rock compositions, the acid component comprises about 5
to 95 weight percent of a mixture comprising about 50 to 99 weight percent
polyphosphoric acid with about 5 to 86 weight percent of the total P.sub.2
O.sub.5 present as polymeric P.sub.2 O.sub.5, about 1 to 25 weight percent
of hydrofluoric acid, and optionally up to 50 weight percent of a catalyst
selected from the group consisting of strong mineral acids, organic
carboxylic acids and oxidizing compounds, where the H.sub.2 O/P.sub.2
O.sub.5 mole ratio in the overall emulsion composition is between about
2.1 and 3.4. The solvent component constitutes about 5 to 95 weight
percent of a solvent blend comprising (a) about 35 to 80 weight percent of
a normally liquid aliphatic hydrocarbon distillate boiling within the
range of about 120.degree. to 550.degree. F., (b) about 4 to about 40
weight percent of a normally liquid aromatic hydrocarbon, (c) about 0.5
to 6 weight percent of an ether of an aliphatic polyhydric alcohol, and
(d) about 1 to 12 weight percent of a lower alkyl monohydric alcohol. The
emulsion also contains about 0.01 to 3.0 weight percent of a cationic or
nonionic surfactant.
The preferred acid emulsions employed in treating siliceous formations
comprise: (1) about 25 to 75 weight percent of an acid component
comprising (a) substantially anhydrous liquid polyphosphoric acid having
about 40 to 75 weight percent of the total P.sub.2 O.sub.5 present as
polymeric P.sub.2 O.sub.5, (b) about 2 to 8 weight percent of hydrofluoric
acid, and (c) optionally, 2 to 40 weight percent of a catalyst selected
from strong mineral acids, carboxylic acids, and oxidizing compounds; (2)
about 25 to 75 weight percent of a solvent component comprising (a) about
40 to 65 weight percent of a normally liquid aliphatic hydrocarbon
distillate boiling within the range of 120.degree. to 550.degree. F., (b)
about 10 to 30 weight percent of a normally liquid aromatic hydrocarbon,
(c) about 1 to 5 weight percent of an ether of an aliphatic polyhydric
alcohol and (d) about 2 to 10 weight percent of an alkyl monohydric
alcohol; and (3) about 0.1 to 1.0 weight percent of a cationic or nonionic
surfactant, and in which the H.sub.2 O/P.sub.2 O.sub.5 mole ratio in the
overall emulsion composition is between 2.2 and 2.8.
In mixed formations, i.e., formations containing calcareous materials in
admixture with siliceous materials, particularly those formations
containing less than 15 percent calcareous material, it is preferred that
the substantially anhydrous liquid acid emulsion composition also contains
hydrochloric acid to aid in dissolving the calcareous materials. However,
it is also preferred that these emulsions contain less acid component than
those previously described for use with predominantly siliceous
formations. In treating mixed formations there is more danger of a
plugging material being precipitated when the acid spends on the formation
than in treating predominantly siliceous formations.
The compositions employed in treating mixed formations broadly comprise the
same ingredients and proportions as are utilized in treating siliceous
formations except that the acid component is present in about 5 to 75
weight percent and the solvent component is present in about 25 to 95
weight percent. Similarly, the preferred compositions for use in treating
mixed formations comprise the same ingredients and proportions as are
preferred for treating siliceous formations except that the acid component
is present in about 20 to 50 weight percent and the solvent component is
present in about 50 to 80 weight percent.
The hydrofluoric acid component may be prepared in situ by adding
crystalline ammonium bifluoride to hydrochloric acid. The hydrogen
chloride reacts with the bifluoride salt to form hydrogen fluoride. The
more salt added, the greater will be the hydrogen fluoride concentration
and the lower will be the hydrogen chloride concentration. Other
preparative methods, including the mixing of hydrofluoric and hydrochloric
acid solutions, can be employed. The use of such mixed acids is generally
preferred.
The major ingredient of the acid component in the emulsion composition is
polyphosphoric acid. Polyphosphoric acid is a generic term used to define
the phosphoric acids having less water of constitution than
orthophosphoric acid. Orthophosphoric acid contains one atom of phosphorus
per molecule and has a theoretical mole ratio of water to phosphorus
pentoxide of 3.0 or greater. Polyphosphoric acids have two or more atoms
of phosphorus in a chain or ring structure in alternating sequence with
oxygen, and a theoretical mole ratio of water to phosphorus pentoxide of
less than 3. Polyphosphoric acid has two general forms, the acyclic and
cyclic. The latter is commonly referred to as metaphosphoric acid. In the
acyclic form, which is derived by limited molecular dehydration of
orthophosphoric acid, the individual chains of phosphorus and oxygen atoms
have terminal ends and a theoretical mole ratio of water to phosphorus
pentoxide of between 2 and 3. In metaphosphoric acid, which is derived
from the acyclic form by continued molecular dehydration, the chain is
endless, forming ring structures. Metaphosphoric acids have theoretical
mole ratios of water to phosphorus pentoxide of 2 or less. However, in
some cases it is preferred that the concentration or dehydration of the
orthophosphoric acid is stopped before the meta species begin to form. The
reason is that the acyclic form of polyphosphoric acid is a much better
complexing agent for aluminum and transition metals like iron, cobalt,
nickel, copper, zinc, etc. Therefore, in geological formations which
contain substantial amounts of compounds of the aforementioned metals, a
polyphosphoric acid-based acidizing mixture with little or no meta
polyphosphoric acid present would be most effective. Thus, the preferred
acid compositions exhibit H.sub.2 O/P.sub.2 O.sub.5 mole ratios above
about 2.
The substantially anhydrous polyphosphoric acid component of the acid
emulsion of this invention may be prepared from either furnace acid or wet
process acid. The various components are introduced into a suitable vessel
with agitation or stirring preferably in a closed vessel or system. Open
vessels are provided with a cooling means to avoid fuming vapors which are
generated by the exothermal mixing of the acid components. The composition
of this invention can be obtained by any suitable method depending on the
source materials used. For example, a dilute wet-process phosphoric acid
is processed to polyphosphoric acid by the addition of dilute,
concentrated, or fuming sulfuric acid followed by concentration of the
mixture through any suitable step, such as evaporation of water or by the
addition of anhydrous phosphorus pentoxide and anhydrous hydrofluoric
acid. When a polyphosphoric acid having an H.sub.2 O/P.sub.2 O.sub.5 mole
ratio of less than 2.6 is used, it is preferred to add concentrated (98%
strength) sulfuric acid to avoid dilution of the P.sub.2 O.sub.5 content.
On the other hand, fuming sulfuric acid, sulfur trioxide, and/or
hydrofluoric acid can be added to polyphosphoric acid to obtain the proper
percent of the other acids in the mixture. It is noted from the drawing
that poly acid begins to form in the equilibrated acid at a mole ratio of
water to P.sub.2 O.sub.5 of about 3.6, i.e., an acid containing about 95
weight percent orthophosphoric acid and still containing about 5 weight
percent of uncombined water. Although this composition has some free
water, the acid is herein referred to as a substantially anhydrous acid
since it is anhydrous in a sense that it has reached its maximum
concentration of orthophosphoric acid and further concentration increases
the poly acid content.
The total of P.sub.2 O.sub.5 content of the non-aqueous
polyphosphoric-based acid emulsion is determined by diluting a
representative sample with water, adding perchloric and nitric acids and
boiling the mixture to convert all forms of phosphoric acid to
orthophosphoric acid. Samples are then passed over a cation exchange resin
to replace the metal cations with hydrogen as these cations will interfere
with subsequent analyses. The ion-exchanged sample is thereafter titrated
with a strong base through two break-points, the first of which
corresponds to the neutralization of the strong acids present,
hydrochloric, nitric, etc., and the most strongly ionized hydrogen of the
orthophosphoric acid. The second breakpoint in the titration curve occurs
at a pH of about 9.5 to 10 and corresponds to neutralization of the second
less strongly ionized hydrogen of the orthophosphoric acid. The difference
in titer between these break-points corresponds to the total phosphate
present which is reported as total P.sub.2 O.sub.5.
The water content of the acid existing as water of constitution and water
of dilution is determined by placing a weighted portion of the acid in a
crucible with zinc oxide in excess of that needed to react with the acid.
The crucible is then weighed, dried at 100.degree. C. for one hour and
placed in an oven at 500.degree. C. for an hour. The loss in weight
corresponds to the total water present in the acid mixture.
To determine the amount of orthophosphoric acid present, various analytical
techniques can be employed. Regardless of the analytical method employed,
prior thereto, the acid sample is prepared by dilution with water, and
then acidification with concentrated sulfuric or nitric acid, followed by
further dilution. Care should be taken to avoid elevated temperatures and
the sample preparation should be done in an ice bath to avoid hydrolysis
of the polyphosphoric acid. The resultant solution is passed over a strong
acid, cation-exchange resin, e.g., Amberlite IR-120H, to remove the
metallic cation impurities which interfere with subsequent analyses.
Immediately after passage over the resin, the acid should be neutralized
to a pH of about 3.5 to about 6.0 to reduce the tendency of polyphosphoric
acid to hydrolyze. The acid is thereafter titrated to the break-point,
falling at a pH between 9.5 and 10 corresponding to the neutralization of
the second, ionized hydrogen of the orthophosphoric acid. Thereafter, an
excess of a silver nitrate solution is added to precipitate silver
orthophosphate and release the third, very weakly ionized hydrogen ion of
the of the orthophosphoric acid. The resultant solution is then titrated
to determine the amount of hydrogen ion released in the silver
precipitation, and this titer value corresponding to the amount of
orthophosphoric acid present in the sample which is reported on a P.sub.2
O.sub.5 basis.
The amount of phosphorus pentoxide existing in the form of polyphosphoric
acid can be determined by the difference between the total P.sub.2 O.sub.5
present and that existing as orthophosphoric acid. When, however, the
polyphosphoric acid is present in low concentrations, constituting 5
percent or less of the total P.sub.2 O.sub.5 content, it is preferred to
analyze for the polyphosphoric acid directly by an anion exchange
chromatography method such as described by Peters and Rieman in Analytica
Chimica Octa, 14, page 131 and by Weiner in Journal American Oil Chemist
Society, 34, page 124.
Catalytic agents which can be used to catalyze the above-described general
reaction are strong mineral acids, organic carboxylic acids and oxidizing
compounds. These catalysts can be employed in concentration ranges of 0 to
50 weight percent and preferably in the range of 2 to 40 weight percent.
Strong mineral acids such as sulfuric, nitric, perchloric and hydrochloric
acids or mixtures thereof can be used. One drawback with using sulfuric
acid as a catalyst in acid mixtures for treating hydrocarbon formations is
the possibility of sludge formation due to sulfuric acid attack on
formation hydrocarbons.
However, for the other utilities mentioned above, sulfuric acid is
preferred for, in addition to the catalytic effect, it aids in dehydration
and depresses the freezing point of polyphosphoric acid to yield a final
product having a freezing point of less than about 30.degree. F., thereby
insuring that the mixture is liquid at ambient temperatures. Furthermore,
sulfuric acid has an additional and surprising effect on the viscosity of
the phosphoric acid for it reduces the acid viscosity by 50 to 75 percent
at concentrations of about 20 to 40 weight percent based on
100-percent-strength sulfuric acid, thereby allowing the use of a
polyphosphoric acid with a lower mole ratio of water to phosphorus
pentoxide.
Suitable organic carboxylic acids useful as catalysts in the
above-described reaction are those that form water-soluble or acid-soluble
salts of alkali metals and alkaline earth metals. For example, formic,
acetic, chloroacetic, peracetic, trichloroacetic, citric, oxalic and
maleic acids can be used.
Typical oxidizing compounds which can be employed according to this
invention include hydrogen peroxide, potassium chromate, potassium
permanganate and chromic acid.
The organic solvent component can be a hydrocarbon solvent, halogenated
hydrocarbon, or a polar solvent or mixtures thereof.
Hydrocarbon solvents such as petroleum solvents, petroleum ether, petroleum
naphtha, gasoline, petroleum spirit, varnish makers' and painters'
naphtha, mineral spirit, kerosene, turbine fuel, high solvency petroleum
naphthas, butanes, 2,2-dimethylbutane, n-hexane, isohexane, n-heptane,
isooctane, isoheptane, pentene-1, pentene-2, mixed pentenes, isoheptene,
isooctenes, naphthas, benzene, toluene, toluene substitutes, xylene,
solvent naphthas, ethylbenzene, diethylbenzene, isopropylbenzene,
amylbenzene, diamylbenzene, triamylbenzene, tetraamylbenzene,
dikerylbenzene-12, amyltoluene, cyclohexane, methylcyclohexane,
tetrahydronaphthalene, decahydronaphthalene, diphenyl, coal-tar creosote,
turpentine, terpene solvents, dipentene, pinene, p-cymene, p-menthane,
pine oils, tall oils and crude oils are suitable.
Halogenated hydrocarbons such as methyl bromide, methyl chloride,
dichloromethane, chloroform, carbon tetrachloride, ethyl chloride,
ethylene dibromide, ethylene chlorobromide, ethylene dichloride,
dichloroethylene, B-trichloroethane, trichloroethylene, trichloroethane,
tetrabromoethane, 1,1,2,2-tetrachloroethane, tetrachloroethylene,
pentachloroethane, hexachloroethane, isopropyl chloride, allyl chloride,
propylene dichloride, mixed amyl chloride, n-amyl chloride,
dichloropentanes, n-hexyl chloride, monochlorohydrin, dichlorohydrin,
epichlorohydrin, glycerol alpha-monochlorohydrin, glycerol alpha,-gamma
dichlorohydrins, monobromobenzenes, dibromobenzene, monochlorobenzene,
o-dichlorobenzene, trichlorobenzene, a-chloronaphthalene, monoamyl
chloronaphthalene, diamyl chloronaphthalene, dichloroethyl ether,
dichlorodiisopropyl ether, triglycol dichloride, halowax oils,
dichlorodifluoromethane, difluorochloroethane, fluorodichloromethane,
fluorotrichloromethane, trifluorotrichloroethane,
dichlorotetrachloroethane and ethylidene fluoride can be used.
Polar solvents and mixtures thereof which can be employed include alcohols,
ketones, ethers and esters. Alcohols such as methanol, ethanol, n-propyl
alcohol, isopropanol, n-butanol, isobutyl alcohol, sec-butanol,
tert-butanol, fusel oil, amyl alcohol, pentasol, n-amyl alcohol, sec-amyl
alcohol, sec-n-amyl alcohol, methyl amyl alcohol, 2-ethylbutyl alcohol,
heptanol-2, heptanol-3, 2-ethylhexanol, capryl alcohol, nonyl alcohol,
nonyl alcohol derivatives, diisobutyl carbinol, n-decanol, undecanol,
trimethylnonyl alcohol, tetradecanol, heptadecanol, phenol, benzyl
alcohol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol,
4-tert-amyl cyclohexyl alcohol, 4-tert-amyl cyclohexyl alcohol, dimethyl
tolyl carbinol, furfuryl alcohol, tetrahydrofurfuryl alcohol, ethylene
glycol, propylene glycol, diethylene glycol, dipropylene glycol, trimethyl
glycol, triethylene glycol, polyethylene glycols, polypropylene glycol
150, 2-methyl-2,4-pentane-diol, glycerol, terpene alcohol, alphaterpineol,
fenchyl alcohol and hydroabietyl alcohol are useful.
Ketones such as acetone, methyl acetone, methyl ethyl ketone, methyl
n-propyl ketone, methyl isobutyl ketone, methyl n-amyl ketone, ethyl butyl
ketone, di-n-propyl ketone, methyl hexyl ketone, diisobutyl ketone,
kiacetone alcohol, acetonyl acetone, mesityl oxide, cyclohexanone, methyl
cyclohexanone, isophorone, and fenchone are suitable.
Ethers including ethyl ether, isopropyl ether, n-butyl ether, diamyl ether,
n-hexyl ether, ethylene glycol monomethyl ether, "Cellosolve", ethylene
glycol mono-n-butyl-ether, ethylene glycol monophenyl ether, ethylene
glycol monobenzyl ether, "Dowanol" 4, "Dowanol" 3, diethylene glycol
monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol
monobutyl ether, "Dowanol" 2, diethyl acetal, 1,2-propylene oxide,
1,4-dioxane, methylal, 2-methyl furan tetrahydrofurane, 2,3-dihydropyran,
pentamethylene oxide, trioxane, terpinyl methyl ether, terpinyl ethylene
glycol ether, dichloroethyl ether, triglycol dichloride, glyderyl
.alpha.-monomethyl ether, glyceryl .alpha., .gamma.-dimethyl ether,
glyceryl .alpha.-mono-n-butyl ether, glyceryl .alpha.-monoisoamyl ether,
and glyceryl .alpha.- .gamma.-diisoamyl ether can be used.
Examples of esters which can be employed include methyl acetate, ethyl
acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, sec-butyl
acetate, isobutyl acetate, amyl acetate, sec-amyl acetate, pentacetate,
methyl amyl acetate, 2-ethyl butyl acetate, cyclohexyl acetate, methyl
cyclohexanyl acetate, ethylene glycol monoacetate, glycol diacetate,
ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether
acetate, methoxy butyl acetate, methyl propionate, ethyl propionate,
n-butyl propionate, amyl propionate, ethyl butyrate, methyl butyrate,
n-butyl butyrate, ethyl hydroxy-iso-butyrate, diethyl carbonate, diethyl
oxalate, dibutyl oxalate, diamyl oxalate, methyl formate, ethyl formate,
butyl formate, amyl formate, methyl lactate, ethyl lactate, butyl lactate,
amyl formate and ethyl silicate.
The surface-active agents or surfactants which can be employed in the
practice of this invention are anionic surfactants, nonionic surfactants
and combinations thereof. Suitable anionic surfactants are sulfonates
characterized by the following generalized formula:
MSO.sub.3 R;
organo-sulfates characterized by the following generalized formula:
MSO.sub.4 R;
organo-phosphates characterized by the following generalized formula:
##STR2##
wherein M is a cation, exemplary of which are hydrogen and alkali metals,
such as sodium, potassium and lithium, and wherein R is a lipophilic
organic group containing up to 200 carbon atoms, and usually containing
from about 6 to 100 carbon atoms, and which may also contain some
hydrophilic functional groups, exemplary of which are alkyl, aryl,
alkylaryl, alkenyl, alkenylaryl, alkylester, alkylpolyester, alkylether,
alkylarylpolyether, cycloalkyl, naphyl, alkylmercaptyl, anthryl and
alkylanthryl groups; and animal fat, vegetable oil, fatty acid and rosin
derivatives.
Exemplary of the surface-active agents that can be employed in the practice
of this invention are commercial surfactants, listed in Table 1.
TABLE 1
______________________________________
Company Trademark Chemical
______________________________________
Nonionic Ethers
Wyandotte Chem.
Pluronic L/62
Polyoxyethylene, Poly-
Corp. oxypropylene
Wyandotte Chem.
Pluronic L/64
Polyoxyethylene, Poly-
Coorp. oxypropylene
Rohm & Haas Triton X-35 Octylphenoxy, Polyoxy-
ethylene ethanol
Rohm & Haas Triton X-45 Octylphenoxy, Polyoxy-
ethylene ethanol
Rohm & Haas Triton X-100 Octylphenoxy, Polyoxy-
ethylene ethanol
Rohm & Haas Triton X-165 Octylphenoxy, Polyoxy-
ethylene ethanol
Rohm & Haas Triton X-305 Octylphenoxy, Polyoxy-
ethylene ethanol
Retzloff Chem.
Retzonal NP-100
Alkylphenoxy, Polyoxy-
ethylene ethanol
Thompson-Hayward
T-mulz 391 Alkylphenoxy, Polyoxy-
Chem. ethylene ethanol
Trylon Chemicals
Emgard 2030 Alkylphenoxy, Polyoxy-
ethylene ethanol
Nonionic Esters
Armour Ind. Chem.
Ethofat 0/15 Polyethoxylated fatty
acids
Armour Ind. Chem.
Ethofat C/15 Polyethoxylated fatty
acids
Atlas Chem. Ind.
Span 20 Sorbitan monolaurate
Atlas Chem. Ind.
Tween 85 Polyoxyethylene
sorbitan trioleate
Baker Caster
Surfactol Glycerol monoricin-
Oil Co. oleate
Baker Caster
Surfactol 365
Ethoxylated caster oil
Oil Co.
Anionic Sulfonates
General Aniline
Igepon AC-78 Coconut oil acid,
esters
& Film Corp. of sodium isethionate
General Aniline
Igepon TN-74 Sodium N-methyl-N-
& Film Corp. palmitoyl taurate
General Aniline
Igepon TE-42 Sodium N-methyl-N-
& Film tallow
tallo acid taurate
American Cyanamid
Aerosol OT Dioctylester sodium
sulfosuccinic acid
Mona Ind. Inc.
Monawet DC-70
Dioctylester sodium
sulfosuccinic acid
Calif. Chem.
Ornite No. S Alkylaryl sodium
sulfonate
Monsanto Co.
Santonerse D Alkylaryl sodium
sulfonate
Anionic Sulfates
E.I. du Pont
Dupanol C Sodium lauryl sulfate
de Nemours & Co.
E.I. du Pont
Dupanol L-144
Sodium alkylaryl
sulfate
de Nemours & Co.
Anionic
Phosphates
General Aniline
Gafac PE-510 Free acid of a complex
& Film Corp. organic phosphate ester
General Aniline
Gafac RE-610 Free acid of a complex
& Film Corp. organic phosphate ester
General Aniline
Gafac MC-470 Sodium slate of a
complex
& Film Corp. organic phosphate ester
Anionic
Miscellaneous
Hercules Inc.
Dresinate 731
Sodium soap of a
modified rosin
______________________________________
Other additives such as acid inhibitors are not normally required in the
emulsion. For example, at temperatures below 160.degree. F. acid
inhibitors are not necessary. However, if additives are employed, they
should be compatible with the acid mixture. Suitable inhibitors useful
above this temperature may include inorganic arsenic compounds and
acetylenic alcohols, thiophenols, heterocyclic nitrogen compounds,
substituted thioureas, rosin amine derivatives, quaternary ammonium
compounds and similar organic agents.
The substantially anhydrous liquid phosphoric acid-based emulsions of this
invention can be used in both matrix acidiz | | |
