U.S. patent application number 11/763006 was filed with the patent office on 2008-12-18 for mono and bis-ester derivatives of pyridinium and quinolinium compounds as environmentally friendly corrosion inhibitors.
Invention is credited to Laxmikant Tiwari.
Application Number | 20080308770 11/763006 |
Document ID | / |
Family ID | 39971017 |
Filed Date | 2008-12-18 |
United States Patent
Application |
20080308770 |
Kind Code |
A1 |
Tiwari; Laxmikant |
December 18, 2008 |
MONO AND BIS-ESTER DERIVATIVES OF PYRIDINIUM AND QUINOLINIUM
COMPOUNDS AS ENVIRONMENTALLY FRIENDLY CORROSION INHIBITORS
Abstract
A quaternary nitrogen-containing corrosion inhibitor of formula
##STR00001## wherein ##STR00002## is an aromatic,
nitrogen-containing ring of 5 to 14 ring atoms, optionally
containing an additional N, O or S ring atom and optionally
substituted with one or more alkyl, alkenyl, aryl, arylalkyl,
cycloalkyl, amino, aminoalkyl, alkoxy, hydroxylalkyl, or cyano
groups, or a mixture thereof, Y is a group of formula
--OC(O)R.sub.1 or --C(O)R.sub.1; L is C.sub.1-C.sub.10 alkyl,
C.sub.2-C.sub.10 alkenyl or a group of formula
CH.sub.2CH(OR.sub.2)CH.sub.2--; R.sub.1 is C.sub.8-C.sub.20 alkyl
or C.sub.8-C.sub.20 alkenyl; R.sub.2 is H or C(O)R.sub.1; R.sub.3
and R.sup.4 are independently selected from H, alkyl, alkenyl,
amino, alkoxy, hydroxylalkyl and cyano; and X is Br, Cl or I is
particularly useful for inhibiting corrosion in oil and gas field
applications.
Inventors: |
Tiwari; Laxmikant;
(Southampton, GB) |
Correspondence
Address: |
Michael B. Martin;Patent and Licensing Department
Nalco Company, 1601 West Diehl Road
Naperville
IL
60563-1198
US
|
Family ID: |
39971017 |
Appl. No.: |
11/763006 |
Filed: |
June 14, 2007 |
Current U.S.
Class: |
252/394 ;
544/224; 544/235; 544/283; 544/335; 546/102; 546/152; 546/339;
548/203; 548/217; 548/235 |
Current CPC
Class: |
C07D 213/04 20130101;
C07D 215/10 20130101; C23F 11/149 20130101 |
Class at
Publication: |
252/394 ;
544/224; 544/235; 544/283; 544/335; 546/102; 546/152; 546/339;
548/203; 548/217; 548/235 |
International
Class: |
C23F 11/14 20060101
C23F011/14; C07D 211/82 20060101 C07D211/82; C07D 215/00 20060101
C07D215/00; C07D 219/00 20060101 C07D219/00; C07D 237/02 20060101
C07D237/02; C07D 237/28 20060101 C07D237/28; C23F 11/16 20060101
C23F011/16; C07D 239/20 20060101 C07D239/20; C07D 239/72 20060101
C07D239/72; C07D 263/32 20060101 C07D263/32; C07D 263/52 20060101
C07D263/52; C07D 277/22 20060101 C07D277/22 |
Claims
1. A quaternary nitrogen-containing corrosion inhibitor of formula
##STR00009## wherein ##STR00010## is an aromatic,
nitrogen-containing ring of 5 to 14 ring atoms, optionally
containing an additional N, O or S ring atom and optionally
substituted with one or more alkyl, alkenyl, aryl, arylalkyl,
cycloalkyl, amino, aminoalkyl, alkoxy, hydroxylalkyl, or cyano
groups, or a mixture thereof; Y is a group of formula
--OC(O)R.sub.1 or --C(O)R.sub.1; L is C.sub.1-C.sub.10 alkyl,
C.sub.2-C.sub.10 alkenyl or a group of formula
--CH.sub.2CH(OR.sub.2)CH.sub.2--; R.sub.1 is C.sub.8-C.sub.20 alkyl
or C.sub.8-C.sub.20 alkenyl; R.sub.2 is H or <(O)R.sub.1; and X
is Br, Cl or I.
2. The corrosion inhibitor of claim 1 wherein the aromatic,
nitrogen-containing ring is selected from oxazole, thiazole,
acridine, cinnoline, quinoxazoline, pyridazine, pyridine,
pryimidine, quinazolinie, quinoline and isoquinoline.
3. The corrosion inhibitor of claim 2 wherein L is C.sub.1-C.sub.10
alkylene or C.sub.2-C.sub.10 alkenylene.
4. The corrosion inhibitor of claim 3 wherein L is methylene.
5. The corrosion inhibitor of claim 2 wherein L is a group of
formula --CH.sub.2CH(OR.sub.2)CH.sub.2--.
6. The corrosion inhibitor of claim 1 wherein the aromatic,
nitrogen-containing ring is selected from pyridine and
quinoline.
7. The corrosion inhibitor of claim 6 wherein L is C.sub.1-C.sub.10
alkylene, C.sub.2-C.sub.10 alkenylene or a group of formula
--CH.sub.2CH(OR.sub.2)CH.sub.2--.
8. The corrosion inhibitor of claim 7 wherein the pyridine or
quinoline is substituted with 1-4 C.sub.1-C.sub.6 alkyl,
C.sub.2-C.sub.6 alkenyl, or C.sub.1-C.sub.6 aminoalkyl groups, or a
mixture thereof.
9. The corrosion inhibitor of claim 8 wherein L is methylene.
10. The corrosion inhibitor of claim 1 of formula ##STR00011##
wherein R.sub.3-R.sub.6 are independently selected from H, alkyl,
alkenyl, aryl, arylalkyl, cycloalkyl, amino, aminoalkyl, alkoxy,
hydroxylalkyl, or cyano groups, or a mixture thereof, or any two of
R.sub.3-R.sub.6 taken together with the ring atoms to which they
are attached may form a fused cycloalkyl.
11. The corrosion inhibitor of claim 10 wherein R.sub.3-R.sub.6 are
independently selected from H, C.sub.1-C.sub.6 alkyl,
C.sub.2-C.sub.6 alkenyl, or C.sub.1-C.sub.6 aminoalkyl, or a
mixture thereof.
12. The corrosion inhibitor of claim 1 of formula ##STR00012##
wherein R.sub.3-R.sub.6 are independently selected from H, alkyl,
alkenyl, aryl, arylalkyl, cycloalkyl, amino, aminoalkyl, alkoxy,
hydroxylalkyl, or cyano groups, or a mixture thereof, or any two of
R.sub.3-R.sub.6 taken together with the ring atoms to which they
are attached may form a fused cycloalkyl or fused heterocyclyl
ring.
13. The corrosion inhibitor of claim 12 wherein R.sub.3-R.sub.6 are
independently selected from H, C.sub.1-C.sub.6 alkyl,
C.sub.2-C.sub.6 alkenyl, or C.sub.1-C.sub.6 aminoalkyl, or a
mixture thereof.
14. A corrosion inhibitor composition comprising 5 to 50 weight
percent of the corrosion inhibitor of claim 1 dispersed or
dissolved in one or more organic solvents.
15. The corrosion inhibitor composition of claim 14 wherein the
organic solvents are selected from alcohols, glycols and aliphatic
and aromatic hydrocarbons.
16. The corrosion inhibitor composition of claim 15 wherein the
organic solvents comprise ethylene glycol monobutyl ether.
17. The corrosion inhibitor composition of claim 16 comprising 5 to
20 weight percent of the corrosion inhibitor of claim 1.
18. A method of inhibiting corrosion of a metallic surface in
contact with a fluid in oil and gas applications comprising adding
to the fluid an effective corrosion-inhibiting amount of one or
more quaternary nitrogen-containing corrosion inhibitors according
to claim 1.
19. The method of claim 18 wherein the fluid comprises oil or gas
and water.
Description
TECHNICAL FIELD
[0001] This invention relates to novel quaternary nitrogen
compounds and compositions comprising the compounds which are
useful as corrosion inhibitors, particularly in oil and gas field
applications and more particularly in situations where they may
come into contact with the natural environment, and to a method of
inhibiting corrosion using the compounds.
BACKGROUND OF THE INVENTION
[0002] Stringent environmental constraints imposed by government
regulation upon the oil and gas producing industry has led to the
need for new "greener" chemistries, which have less environmental
impact. This environmental drive has been spearheaded by North Sea
Regulators such as CEFAS, and due to their success similar programs
are being implemented in other oil producing regions. Operators now
demand identical levels of performance with existing treatments
along with the fulfillment of the new environmental criteria for
any chemicals that may be contained, for example, in rig overboard
discharge.
[0003] Corrosion inhibitors are given particular attention due to
their inherent design to partition into the aqueous phase. The
environmental impact of a corrosion inhibitor is often defined by
three criteria, biodegradation, bioaccumulation and toxicity. All
three criteria have benchmarks that must be met for a chemical to
be permitted for use, with different emphasis on each depending on
which regulator controls the waters.
[0004] Quaternary nitrogen compounds (Quats) have been used
extensively as they form a film on the surface of steel, are stable
over a wide range of pH and temperature, cost effective, efficient
in sour conditions and inhibit microbially induced corrosion (MIC).
See, for example, U.S. Pat. Nos. 7,057,050, 6,488,868, 5,756,004
and WO 2003042428 A1. However, due to their inherent biostatic
properties their biotoxicity profile is often unacceptable and the
compounds are not readily biodegradeable.
[0005] Accordingly, there is an ongoing need for new, effective,
environmentally friendly corrosion inhibitors which meet the new
regulatory criteria.
SUMMARY OF THE INVENTION
[0006] In an embodiment, this invention is a quaternary
nitrogen-containing corrosion inhibitor of formula
##STR00003##
wherein
##STR00004##
is an aromatic, nitrogen-containing ring of 5 to 14 ring atoms,
optionally containing an additional N, O or S ring atom and
optionally substituted with one or more alkyl, alkenyl, aryl,
arylalkyl, cycloalkyl, amino, aminoalkyl, alkoxy, hydroxylalkyl, or
cyano groups, or a mixture thereof; Y is a group of formula
C(O)R.sub.1 or C(O)R.sub.1; L is C.sub.1-C.sub.10 alkyl,
C.sub.2-C.sub.10 alkenyl or a group of formula
--CH.sub.2CH(OR.sub.2)CH.sub.2--; R.sub.1 is C.sub.8-C.sub.20 alkyl
or C.sub.9-C.sub.20 alkenyl; R.sub.2 is H or --C(O)R.sub.1; R.sub.3
and R.sub.4 are independently selected from H, alkyl, alkenyl,
amino, alkoxy, hydroxylalkyl and cyano; and X is Br, Cl or I.
[0007] The corrosion inhibitor of the invention has a lower
environmental impact when compared to existing commercial
treatments by virtue of their low toxicity, higher biodegradation
and lower bioaccumulation. In addition, the corrosion inhibitors of
this invention are less volatile, hence less malodorous than,
existing alkypyridine corrosion inhibitors.
DETAILED DESCRIPTION
[0008] As used herein, "Alkenyl" means a monovalent group derived
from a straight or branched hydrocarbon containing at least one
carbon-carbon double bond by the removal of a single hydrogen atom.
Alkenyl groups include, for example, ethenyl, propenyl, butenyl,
1-methyl-2-buten-1-yl and the like.
[0009] "Alkoxy" means an alkyl group, as defined above, attached to
the parent molecular moiety through an oxygen atom. Representative
alkoxy groups include methoxy, ethoxy, propoxy, butoxy, and the
like.
[0010] "Alkyl" means a monovalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of a single
hydrogen atom. Representative alkyl groups include methyl, ethyl,
n- and iso-propyl, n-, sec-, iso- and tert-butyl, and the like.
[0011] "Alkylene" means a divalent group derived from a straight or
branched chain saturated hydrocarbon by the removal of two hydrogen
atoms, for example methylene, 1,2-ethylene, 1,1-ethylene,
1,3-propylene, 2,2-dimethylpropylene, and the like.
[0012] "Amino" means a group having the structure --NR'R'' wherein
R' and R'' are independently selected from H and alkyl, as
previously defined. Additionally, R' and R'' taken together may
optionally be --(CH.sub.2).sub.k-- where k is an integer of from 2
to 6. Representative amino groups include, amino (--NH.sub.2),
methylamino, ethylamino, n- and iso-propylamino, dimethylamino,
methylethylamino, piperidino, and the like.
[0013] "Aminoalkyl" means an alkyl group as defined herein
substituted by one or more amino groups as defined herein.
Representative aminoalkyl groups include aminomethyl,
dimethylaminomethyl, diethylaminomethyl, 2-aminoethyl,
2-dimethylaminoethyl, 2-ethylaminoethyl, and the like.
[0014] "Aryl" means substituted and unsubstituted aromatic
carbocyclic radicals and substituted and unsubstituted heterocyclic
radicals having about 5 to about 14 ring atoms. Representative aryl
include phenyl naphthyl, phenanthryl, anthracyl, pyridyl, furyl,
pyrrolyl, quinolyl, thienyl, thiazolyl, pyrimidyl, indolyl, and the
like. The aryl is optionally substituted with one or more groups
selected from hydroxy, halogen, C.sub.1-C.sub.4 alkyl and
C.sub.1-C.sub.4 alkoxy.
[0015] "Arylalkyl" means an aryl group attached to the parent
molecular moiety through an alkylene group. Representative
arylalkyl groups include benzyl, phenethyl, napth-1-ylmethyl,
phenylpropyl, and the like.
[0016] "Cycloalkyl" means a non-aromatic ring system of about 5 to
about 10 carbon atoms, preferably of about 5 to about 10 carbon
atoms. The cycloalkyl optionally contains an additional N, O or S
ring atom. Preferred ring sizes of rings of the ring system include
about 5 to about 6 ring atoms. The cycloalkyl is optionally
substituted with one or more groups selected from hydroxy, halogen,
C.sub.1-C.sub.4 alkyl and C.sub.1-C.sub.4 alkoxy. Representative
cycloalkyl include cyclopentyl, cyclohexyl, cycloheptyl, piperidyl,
pyrrolidinyl, piperazinyl, morpholinyl, thiomorpholinyl,
thiazolidinyl, 1,3-dioxolanyl, 1,4-dioxanyl, tetrahydrofuranyl,
tetrahydrothiophenyl, tetrahydrothiopyranyl, and the like. "Fused
cycloalkyl" means a cycloalkyl in which at least two of the ring
atoms of the cycloalkyl are also atoms contained in the ring system
of the aromatic, nitrogen containing ring of the corrosion
inhibitor of this invention.
[0017] "Hydroxyalkyl" means an alkyl group as defined herein
substituted with one or more hydroxyl (--OH) groups. Representative
hydroxyalkyl groups include hydroxymethyl, 2-hydroxyethyl,
2-hydroxypropyl, and the like.
[0018] The preparation of representative inhibitors of this
invention where L is <H.sub.2CH(OR.sub.2)CH.sub.2-- is shown in
Scheme 1.
##STR00005##
[0019] As shown in Scheme 1,1-halo-2,3-dihydroxypropane 2 is
prepared by ring opening of epihalohydrin 1 where X is Br, Cl or I,
in the presence of catalytic acid such as HCl. Condensation of 2
with long chain fatty acids R.sub.1CO.sub.2H, where R.sub.1 is
defined herein at a temperature of about 100 to about 170.degree.
C. results in formation of a mixture of mono- and bis-haloester
derivatives 3 and 4. Heating the mixture of haloesters 3 and 4 at a
temperature of about 100 to about 160.degree. C. with the aromatic,
nitrogen containing ring compound 5, for example at about
150.degree. C. for 2 hours, results in formation of a mixture of
inhibitors 6 and 7.
[0020] The preparation of representative inhibitors of this
invention where L is C.sub.1-C.sub.10 alkylene or C.sub.2-C.sub.10
alkenylene is shown in Scheme 2.
##STR00006##
[0021] As shown in Scheme 2, long chain haloester 10 where X and
R.sub.1 are defined herein may be prepared by esterification of
haloacid 8 with long-chain alcohol 9, for example by heating a
mixture of 8 and 9 at a temperature of about 110 to about
140.degree. C. in the presence of a catalytic acid such as HCl.
Reaction of haloester 10 with the aromatic, nitrogen containing
ring compound 5, as described in Scheme 1 above results in
formation of inhibitor 11.
[0022] Representative long chain fatty acids R.sub.1CO.sub.2H
include caprylic acid, nonanoic acid, capric acid, undecanoic acid,
lauric acid, tridecanoic acid, myristic acid, palmitoleic acid,
tall oil fatty acid (mixture of oleic, linoleic and linolenic
acids), stearic acid, palmitic acid, arachidic acid, arachidonic
acid, oleic acid, 9,11,13-octadecatrienoic acid,
5,8,11,14-eicosatetracnoic acid, eicosenoic acid, heneicosenoic
acid, erucic acid, heneicosanoic acid, behenic acid,
3-methylhexadecanoic acid; 7-methylhexadecanoic acid,
13-methylhexadecanoic acid; 14-methyl-11-eicosenoic acid, and the
like and mixtures thereof.
[0023] In an embodiment, the fatty acid is tall oil fatty acid.
[0024] In an embodiment, the fatty acid is lauric acid.
[0025] Representative aromatic nitrogen-containing ring compounds 5
include substituted and unsubstituted oxazole, thiazole, acridine,
cinnoline, quinoxazoline, pyridazine, pyridine, pyrimidine,
quinazoline, quinoline and isoquinoline. The ring compounds may be
unsubstituted or substituted with 1-4 substituents independently
selected from alkyl, alkenyl, aryl, arylalkyl, cycloalkyl, amino,
aminoalkyl, alkoxy, hydroxylalkyl, and cyano, or a mixture
thereof.
[0026] In an embodiment, the aromatic nitrogen-containing ring
compounds are selected from pyridine and quinoline.
[0027] Representative substituted pyridine and quinoline rings
include 4-methylpyridine, 2-methylpyridine,
2-methyl-3,5-diethylpyridine, 3-ethyl-4-methylpyridine,
2-methyl-5-(but-2-phenyl)pyridine,
2-(prop-1-phenyl)-5-ethylpyridine, 2-vinylpyridine,
4-vinylpyridine, 3-pyridiylcarbinol, 3-methylpyridine,
3,5-diethyl-1,2-dihydro-1-phenyl-2-propylpyridine,
2,6-dimethylpyridine, 3-cyanopyridine, 2-cyanopyridine,
2,3,5-trimethylpyridine, 2,4,6-trimethylpyridine,
2-amino-3-methylpyridine, 2-aminopyridine,
2-methyl-5-(2-ethylaminoethyl)pyridine, 2,4-dimethylquinoline,
2,6-dimethylquinoline, 2,7-dimethylquinoline,
4-methoxy-2-phenylquinoline,
2-(3,4-methylenedioxyphenylethyl)quinoline, 2-n-propylquinoline,
2-(prop-1-phenyl)quinoline, 4-methoxy-2-n-pentylquinoline,
chimamine, cusparine, skimmianine, chinanine, 4-aminoquinoline,
4-methyl-2-phenylquinoline, and the like.
[0028] In an embodiment, the pyrindine and quinoline rings are
substituted with 1-4 C.sub.1-C.sub.6 alkyl or C.sub.2-C.sub.6
alkenyl, C.sub.1-C.sub.6 aminoalkyl groups, or a mixture
thereof.
[0029] In an embodiment, the quaternary nitrogen compound of the
invention has formula
##STR00007##
where X and n are defined herein and R.sub.3-R.sub.6 are
independently selected from H, alkyl, alkenyl, aryl, arylalkyl,
amino, aminoalkyl, alkoxy, hydroxylalkyl, and cyano groups, or a
mixture thereof, or any two of R.sub.3-R.sub.6 taken together with
the ring atoms to which they are attached may form a fused
cycloalkyl or fused heterocyclyl ring. It should be noted that in
the foregoing structures, the solid lines to the groups
R.sub.3-R.sub.6 are intended to indicate that R.sub.3-R.sub.6 may
be attached any carbon atom in the pyridine ring.
[0030] In an embodiment, the quaternary nitrogen compound has
formula
##STR00008##
where X and n are defined herein and R.sub.3-R.sub.6 are
independently selected from H, alkyl, alkenyl, aryl, arylalkyl,
amino, aminoalkyl, alkoxy, hydroxylalkyl, and cyano groups, or a
mixture thereof, or any two of R.sub.3-R.sub.6 taken together with
the ring atoms to which they are attached may form a fused
cycloalkyl or fused heterocyclyl ring. It should be noted that in
the foregoing structures, the solid lines to the groups
R.sub.3-R.sub.6 are intended to indicate that R.sub.3-R may be
attached any carbon atom in the quinoline ring system.
[0031] The quaternary nitrogen-containing corrosion inhibitor of
the present invention can be used in any system exposed to fluids
(i.e., liquid, gas, slurry or mixture thereof) containing a metal
corrosion agent where improved corrosion inhibition is desired.
However, the corrosion inhibitors of the present invention are
particularly well-suited for use in oil and gas field applications
and refinery operations.
[0032] With respect to such oil and gas field applications, the
corrosion inhibitor of the present invention may be added to oil
and/or gas fluids in the form of a solution or dispersion in one or
more organic solvents or a mixture of water and organic solvent.
Examples of suitable solvents are alcohols such as methanol,
ethanol, isopropanol, isobutanol, secondary butanol, glycols such
as ethylene glycol, and ethylene glycol monobutyl ether ("EGMBE"),
and the like, and aliphatic and aromatic hydrocarbons including
heavy aromatic naphtha. The selection of the solvent particular
corrosion inhibitor(s) used. For example, the corrosion inhibitors
are typically sparingly soluble or insoluble in water, but may be
suitably formulated in a mixture of water and one or more alcohols
or glycols. Similarly, the corrosion inhibitors may be suitably
formulated in heavy aromatic naphtha by incorporating one or more
alcohols or glycols in the composition.
[0033] In an embodiment, the organic solvents comprise ethylene
glycol monobutyl ether.
[0034] The amount of active ingredient in a corrosion inhibitor
formulation required to sufficiently reduce the rate of corrosion
varies with the system in which it is used. Methods for monitoring
the severity of corrosion in different systems are well-known to
those skilled in the art, and may be used to decide the effective
amount of active ingredient required in a particular situation. The
compounds may be used to impart the property of corrosion
inhibition to a composition for use in an oil or gas field
application and may have one or more functions other than corrosion
inhibition, e.g. scale inhibition.
[0035] In an embodiment, this invention is a corrosion inhibitor
composition comprising 5 to 50 weight percent of one or more
quaternary nitrogen-containing corrosion inhibitors according to
the invention dispersed or dissolved in one or more organic
solvents.
[0036] In an embodiment, the corrosion inhibitor composition
comprises 5 to 20 weight percent of the quaternary
nitrogen-containing corrosion inhibitors.
[0037] The quaternary nitrogen-containing corrosion inhibitors
described herein have proven to be particularly effective for
inhibiting corrosion of mild steel in hydrocarbon, oil/brine
mixtures and aqueous systems under a variety of conditions. The
inhibitors claimed herein are useful in both sour systems, i.e.,
systems having a relatively high H.sub.2S concentration and sweet
systems, i.e., systems having a relatively high CO.sub.2
concentration. In the case of sweet systems, the inhibitors are
advantageously used in combination with a sulphur-containing
material such as 2-mercaptoethanol, sodium thiosulfate,
thioglycolic acid and alkyl thiols.
[0038] Although fluid content of flow lines may vary, the inhibitor
may be used in a variety of environments. Oil cuts in the field can
range from less than 1% (oil field) to 100% (refinery) oil, while
the nature of the water can range from 0 to 300,000 ppm TDS (total
dissolved solids). In addition, the inhibitors of the present
invention are also useful in large diameter flow lines of from
about 1 inch to about 4 feet in diameter, small gathering lines,
small flow lines and headers. In a preferred method, the inhibitor
is added at a point in the flow line upstream from the point at
which corrosion prevention is desired.
[0039] In practice, the inhibitors of the present invention are
preferably added to the flow line continuously to maintain a
corrosion inhibiting dose of from about 0.01 to about 5000 ppm.
More preferably, the corrosion inhibiting dose is from about 0.1 to
about 500 ppm. In a most preferred embodiment of the present
invention, the corrosion inhibiting dose is from about 1 to about
250 ppm. Although a most preferred use of the corrosion inhibitors
of the present invention is for mild steel flow lines, it is
believed that the inhibitors are also effective in inhibiting
corrosion in other types of metallurgy. In certain cases, batch
treatments are the method of choice for application of the
inhibitors of the present invention. However, the invention can
also be practiced using a continuous process. Dosage rates for
batch treatments range from about 0.1 to about 50,000 ppm. In a
preferred embodiment of the present invention, the flow rate of the
flow line in which the inhibitor composition is used is between 0
and 100 feet per second. A more preferred flow rate is between 0.1
and 50 feet per second.
[0040] The inhibitors of the present invention may be used alone or
in combination with other compounds. Typical formulations include
pour point depressants and/or surfactants, Examples of suitable
pour point depressants are C.sub.1 to C.sub.3 linear or branched
alcohols, ethylene and propylene glycol. Examples of suitable
surfactants are ethoxylated nonylphenols and/or ethoxylated amines
as wetting agents or additives for dispersing the inhibitor into
the fluid stream to which they are added. The surfactant is
advantageously water soluble to allow the product to better wet the
surface of the flow line where corrosion may take place. Water
soluble surfactants utilized may be non-ionic, cationic or anionic
and will generally have a hydrophilic-lipophilic (HLB) value of
about 1. Oil soluble surfactants may be utilized if it is desired
to disperse the inhibitor composition into a hydrocarbon fluid. Oil
soluble surfactants may be non-ionic, cationic or anionic. These
surfactants typically have an HLB value less than 7.
[0041] Other compounds which may also be blended with the
inhibitors include quaternary amines, such as fatty, cyclic or
aromatic amines quaternized with lower alkyl halides or benzyl
chloride and certain amides. In addition, formulations including
the inhibitors of the present invention may include filming agents
such as p-toluenesulfonic acid and dodecylbenzenesulfonic acid.
Formulations including inhibitors of the present invention may also
include filming agents such as imidazolines and/or mono or bis
phosphate esters. The corrosion inhibitor may also contain
components which are typically included in corrosion inhibiting
compositions, such as scale inhibitors, demulsifiers, and/or
surfactants. In some instances, it may be desirable to include a
biocide in the composition.
[0042] The formulation is preferably produced by blending the
ingredients into a homogeneous mixture.
[0043] The resultant inhibitor formulation may be used in a variety
of petroleum operations in the oil and gas industry. It can be used
to treat systems used in primary, secondary and tertiary oil and
gas recovery. The inhibitor formulation may be introduced to such
systems in accordance with techniques well-known to those skilled
in the art. For example, one technique in which the inhibitor
formulation can be used is the squeeze treating technique, whereby
the inhibitor formulation is injected under pressure into a
producing formation, adsorbed onto the strata and absorbed as the
fluids are produced. The inhibitor formulation can further be added
in water flooding operations of secondary oil recovery, as well as
be added to pipelines, transmission lines and refinery units. The
inhibitor formulation may also be used to inhibit acid solution in
well-acidizing operations.
[0044] The foregoing may be better understood by reference to the
following Examples, which are presented for purposes of
illustration and are not intended to limit the scope of the
invention.
EXAMPLE 1
[0045] Epichlorohydrin (34 g, 0.36 m) is heated at 80.degree. C.
with a catalytic amount of concentrated hydrochloric acid (1 ml)
for 20 minutes to open the ring and obtain
1-chloro-2,3-dihydroxy-propane. This is condensed with 1.5 equiv.
of tall oil fatty acids (155 g, 0.55 m) at 150.degree. C. for 3
hours to obtain a mixture of mono and bis esters. Any residual
hydrochloric acid is neutralised with solid sodium bicarbonate.
Substituted pyridine (Alkolidine 12, available from Lonza Ltd.,
Basel, Switzerland, 95 g, 0.55 m) is added and the reaction mixture
is heated at 150.degree. C. for 2 hours to obtain the corresponding
substituted pyridinium salt. Sodium chloride is filtered off and
any other inorganics are removed by dissolving in water. Yield: 260
g.
EXAMPLE 2
[0046] Chloroacetic acid (20 g, 0.211 m) is heated with n-octanol
(28 g, 0.22 m) at 120.degree. C. for 2 hours in the presence of a
catalytic amount of concentrated hydrochloric acid. The reaction
mixture is allowed to cool and substituted pyridine (Alkolidine 12,
42 g, 0.22 m) is added. The reaction mixture is heated at
130.degree. C. for another 2 hours to provide the substituted alkyl
pyridinium ester. Yield 86 g.
EXAMPLE 3
Performance Testing
[0047] Standard Linear Polarisation Resistance (LPR) techniques in
a `bubble` or stirred kettle assembly are used to measure the
instatanteous corrosion rate in the brine solution as a function of
time. Synthetic seawater (deionised water containing 3% sodium
chloride) saturated with CO.sub.2 and de-aromatised kerosene
(LVT-200) are used in a 90:10 ratio at 60.degree. C.
[0048] An automated electrochemical measurement system (ACM
Instruments Gill 12) and associated software is used to conduct
electrochemical measurements. Three pin probes constructed from
type C1018 mild steel are used for all bubble test and Rotating
Cylinder Electrode (RCE) measurements. Standard ranges of
concentrations are examined to generate performance concentration
curves in an environment where the inhibitor species has been
allowed to partition. A blank corrosion rate for each cell is
measured every 10 minutes for two hours whereupon chemical
injection is made into the hydrocarbon phase. The corrosion rate is
then continuously measured for a subsequent 18 hours. RCE
complements LPR by virtue of its ability to generate a moderate
shear stress (10 Pa) in the solution, which is CO.sub.2 sparged
synthetic brine (deionised water containing 3% sodium chloride) at
60.degree. C.
LPR Bubble and RCE Testing
[0049] Corrosion inhibitor performances are initially investigated
using LPR bubble tests where general corrosion rates of type C1018
steel electrodes are measured in CO.sub.2 sparged synthetic brine
and dearomatised kerosene mixture (90:10) for 18 hours at
60.degree. C. in the presence of corrosion inhibitors.
[0050] In the data shown below, Inhibitor 1 is an alkyl
quinolinium-based corrosion inhibitor comprising a mixture of mono-
and disubstituted esters of lauric acid. Inhibitor 2 is an alkyl
quinolinium-based corrosion inhibitor comprising a mixture of mono-
and disubstituted esters of tall oil fatty acid. Inhibitor 3 is an
alkyl pyridinium-based corrosion inhibitor comprising a mixture of
mono- and disubstituted esters of lauric acid. Inhibitor 4 is an
alkyl pyridinium-based corrosion inhibitor comprising a mixture of
mono- and disubstituted esters of tall oil fatty acid. Inhibitors
1-4 are prepared according to the method of Example 1.
[0051] The inhibitors are formulated in compositions consisting of
inhibitor (20 weight percent), thioglycolic acid (20 weight
percent) and EGMBE (60 weight percent). Corrosion protection
results are presented in Table 1.
TABLE-US-00001 TABLE 1 Corrosion protection (%) after 18 hrs
Inhibitor 2.5 ppm 5 ppm 10 ppm 25 ppm Commercial 94 96 96 98 alkyl
pyridine.sup.1 4 91 95 96 97 3 88 90 91 98 1 97 97 99 99 2 91 96 97
98 .sup.1Alkolidine 12, Lonza Ltd., Basel, Switzerland.
[0052] As shown in Table 1, formulations comprising representative
inhibitors of the invention provide corrosion protection comparable
to a commercially available alkyl pyridine corrosion inhibitor over
a range of dosages.
[0053] The general corrosion rate before and after the addition of
inhibitors at a concentration of 25 ppm is shown in Table 2.
TABLE-US-00002 TABLE 2 Inhibited Corrosion Protection Pre-Corrosion
Corrosion Rate Inhibitor (%) Rate (mmpy) (mmpy) Commercial 98 6.350
0.127 alkyl pyridine.sup.1 2 97 6.526 0.192 3 98 6.163 0.128
.sup.1Alkolidine 12, Lonza Ltd., Basel, Switzerland.
[0054] The inhibitor performances are further assessed by RCE. A
summary of RCE test results is shown in Table 3.
TABLE-US-00003 TABLE 3 Inhibited Corrosion Protection Pre-Corrosion
Corrosion Rate Inhibitor (%) Rate (mmpy) (mmpy) Commercial 96 9.846
0.384 alkyl pyridine.sup.1 4 95 5.666 0.292 3 94 9.344 0.556
.sup.1Alkolidine 12, Lonza Ltd., Basel, Switzerland.
[0055] As shown in Tables 2 and 3, corrosion rates in the presence
of representative inhibitors of this invention and commercial alkyl
pyridine corrosion inhibitors are comparable.
EXAMPLE 4
Emulsification Tendency Testing
[0056] Corrosion inhibitor injected into produced fluids will
concentrate to some extent in the water phase but a significant
portion will reside at oil/water interface. High concentrations of
corrosion inhibitor can cause significant emulsion problems.
Screening is carried out to assess the emulsification tendency of
inhibitors in presence of de-aromatised kerosene (LVT-200).
[0057] The test procedure used involves mixing synthetic
hydrocarbon LVT-200 and brine in glass bottles and the addition of
corrosion inhibitor at a concentration that is huge excess to that
which is actually applied in the field, i.e., 100, 200 and 500 ppm.
After addition of the corrosion inhibitor, the bottles are shaken
for 2 minutes and visual assessment is made at time intervals of 2,
5, and 10 minutes and compared with the blank, which does not
contain any inhibitor.
[0058] Comparison of emulsification tendency of representative
Inhibitor 2 and a commercial alkyl pyridine reveals that Inhibitor
I and the commercial inhibitor behave comparably with respect to
water quality.
EXAMPLE 5
Environmental Profiles
[0059] The environmental impact of a production chemical is
typically defined by three tests: biodegradation, bioaccumulation
and toxicity. All three criteria have limits that must be achieved
in order for a chemical to be permitted for use. In order for a
product to be used without restriction offshore, two of the
following three criteria must be satisfied.sup.1: [0060]
Biodegradation must be greater than 60% (if less than 20% material
is automatically marked for substitution) [0061] Bioaccumulation as
measured by Octanol/Water partitioning coefficient (LogP.sub.o/w)
must be below 3 (or molecular weights higher than 700) [0062]
Toxicity to the most sensitive marine species (typically
Skeletonema) must be greater than LC.sub.50 or EC.sub.50 of 10
ppm.
[0063] Three environmental screens are performed to measure
toxicity, bioaccumulation and biodegradation of the corrosion
inhibitors. The environmental profile of existing and modified
inhibitors is shown in Table 4 below.
TABLE-US-00004 TABLE 4 Toxicity Bioaccumulation Biodegradation,
Inhibitor EC.sub.50 (ppm) LogP.sub.o/w (Mol. Wt.) t = 28 days Green
>10 <3 (or Mw > 700) >60% Commercial 3.3 2.67 <20%
alkyl pyridine.sup.1 2 23 Mw > 700 50%* 3 >25 Mw > 700 --
.sup.1Alkolidine 12, Lonza Ltd., Basel, Switzerland.
[0064] As shown in Table 4, Inhibitor 2 meets all the requirements
to qualify as a "Green" corrosion inhibitor unlike the parent
compound alkyl pyridine. Similarly Inhibitor 3 has a much improved
environmental profile compared to alkyl pyridine which fails to
qualify as "Green" inhibitor due to less than 20% biodegradation
after 28 days in sea water.
[0065] It should be understood that various changes and
modifications to the presently preferred embodiments described
herein will be apparent to those skilled in the art. Such changes
and modifications can be made without departing from the spirit and
scope of the present subject matter and without diminishing its
intended advantages. It is therefore intended that such changes and
modifications be covered by the appended claims.
* * * * *