U.S. patent application number 17/099523 was filed with the patent office on 2021-06-17 for synergistic blends of anti-agglomerant gas hydrate inhibitors with n-alkanoyl-polyhydroxyalkylamines.
This patent application is currently assigned to Clariant International, Ltd.. The applicant listed for this patent is Clariant International, Ltd.. Invention is credited to Felix Hoevelmann, Matthias KRULL, Dirk LEINWEBER, Zachary Thomas WARD, Jonathan James Wylde.
Application Number | 20210179922 17/099523 |
Document ID | / |
Family ID | 1000005251135 |
Filed Date | 2021-06-17 |
United States Patent
Application |
20210179922 |
Kind Code |
A1 |
LEINWEBER; Dirk ; et
al. |
June 17, 2021 |
Synergistic Blends Of Anti-Agglomerant Gas Hydrate Inhibitors With
N-Alkanoyl-Polyhydroxyalkylamines
Abstract
The present disclosure relates to a gas hydrate inhibitor
composition comprising an amphiphile having a hydrophobic tail
linked to a hydrophilic head group by a linking moiety, the
amphiphile having the general formula (1)
[R.sup.5-L-N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.- (1) wherein
each of R.sup.1 and R.sup.2 is independently an alkyl group having
from 1 to 5 carbon atoms; or wherein the nitrogen atom and the
R.sup.1 and R.sup.2 groups together form a substituted or
unsubstituted heterocyclic group; R.sup.3 is present or not as
hydrogen or an alkyl group having from 1 to 8 carbon atoms which
optionally bears a hydroxy group or a carboxy group in the
2-position; L is a linking moiety comprising an optionally
substituted hydrocarbyl group having at least 2 adjacent carbon
atoms, at least one heteroatom selected from nitrogen and oxygen,
and optionally one or more further heteroatoms; R.sup.5 is a
hydrocarbyl group having from 6 to 22 carbon atoms; and X.sup.- is
present as an anion when R.sup.3 is present; and a nonionic
surfactant which is selected from N-acylated polyhydroxyalkylamines
and a method of using the gas hydrate inhibitor composition.
Inventors: |
LEINWEBER; Dirk; (Kelkheim,
DE) ; WARD; Zachary Thomas; (Spring, TX) ;
Hoevelmann; Felix; (Muhldorf, DE) ; Wylde; Jonathan
James; (The Woodlands, TX) ; KRULL; Matthias;
(Harxheim, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Clariant International, Ltd. |
Muttenz 1 |
|
CH |
|
|
Assignee: |
Clariant International,
Ltd.
Muttenz 1
CH
|
Family ID: |
1000005251135 |
Appl. No.: |
17/099523 |
Filed: |
November 16, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62946679 |
Dec 11, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 2208/22 20130101;
C09K 8/52 20130101 |
International
Class: |
C09K 8/52 20060101
C09K008/52 |
Claims
1. A gas hydrate inhibitor composition comprising A) from 5 to 95
weight-% of an amphiphile having a hydrophobic tail linked to a
hydrophilic head group by a linking moiety, the amphiphile having
the general formula (1)
[R.sup.5-L-N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.- (1) wherein
each of R.sup.1 and R.sup.2 is independently an alkyl group having
from 1 to 5 carbon atoms; or wherein the nitrogen atom and the
R.sup.1 and R.sup.2 groups together form a substituted or
unsubstituted heterocyclic group; R.sup.3 is present or not as
hydrogen or an alkyl group having from 1 to 8 carbon atoms which
optionally bears a hydroxy group or a carboxy group in the
2-position; L is a linking moiety comprising an optionally
substituted hydrocarbyl group having at least 2 adjacent carbon
atoms, at least one heteroatom selected from nitrogen and oxygen,
and optionally one or more further heteroatoms; R.sup.5 is a
hydrocarbyl group having from 6 to 22 carbon atoms; and X.sup.- is
present as an anion when R.sup.3 is present; and B) from 5 to 95
weight-% of a nonionic surfactant which is selected from N-acylated
polyhydroxyalkylamines.
2. The gas hydrate inhibitor composition according to claim 1,
wherein R.sup.1 and R.sup.2 independently are alkyl groups having
from 3 to 5 carbon atoms.
3. The gas hydrate inhibitor composition according to claim 1,
wherein R.sup.5 is an alkyl or alkenyl group having between 8 and
20 carbon atoms.
4. The gas hydrate inhibitor composition according to claim 1,
wherein R.sup.3 is present as hydrogen or as a methyl group.
5. The gas hydrate inhibitor according to claim 1, wherein X.sup.-
is selected from the group consisting of hydroxide, carboxylate,
halide, sulphate, nitrite, nitrate, organic sulfonate, phosphate,
organic phosphonate and combinations thereof.
6. The gas hydrate inhibitor composition according to claim 1,
wherein X.sup.- is a carboxylate anion.
7. The gas hydrate inhibitor composition according to claim 6,
wherein the carboxylate anion is selected from the group consisting
of formate, acetate, propionate, acrylate, methacrylate and any
combination thereof.
8. The gas hydrate inhibitor composition according to claim 1,
wherein the linking moiety L contains a connecting chain which
constitutes the direct connection between the hydrophilic head
group --N(R.sup.1)(R.sup.2) respectively
--[N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.- and the lipophilic
tail R.sup.5, which comprises at least 2 adjacent carbon atoms, at
least one heteroatom selected from nitrogen and oxygen and
optionally one or more further heteroatoms and which may have
substituents attached to it.
9. The gas hydrate inhibitor composition according to claim 8,
wherein the connecting chain is an optionally substituted
heteroaliphatic chain comprising at least one heteroatom selected
from nitrogen and oxygen.
10. The gas hydrate inhibitor composition according to claim 9,
wherein the at least one heteroatom is nitrogen.
11. The gas hydrate inhibitor composition according to claim 8,
wherein the connecting chain is a heteroaliphatic chain wherein one
or more non-adjacent CH.sub.2 groups are replaced by a heteroatom
selected from nitrogen and oxygen and optionally by one or more
further heteroatom(s) which are part of a functional group selected
from the group consisting of --C(.dbd.O)--O--, --O--C(.dbd.O)--,
--C(.dbd.O)--NR.sup.6--, --NR.sup.7--C(.dbd.O), --NR.sup.6--,
--R.sup.7N--, --O--, --S--, --(SO)-- or --(SO.sub.2)--, wherein
R.sup.6 is hydrogen or an alkyl group having from 1 to 5 carbon
atoms, and R.sup.7 is hydrogen or an organic moiety having from 1
to 20 carbon atoms.
12. The gas hydrate inhibitor composition according to claim 8,
wherein the connecting chain comprises one or more aliphatic groups
having 2 to 10 adjacent carbon atoms, which are connected to each
other and/or the hydrophobic tail by a heteroatom which may be part
of a functional group selected from the group consisting of
--C(.dbd.O)--O--, --O--C(.dbd.O)--, --C(.dbd.O)--N(R.sup.6)--,
--N(R.sup.7)--C(.dbd.O)--, --N(R.sup.6)--, --(R.sup.7)N--, --O--,
--S--, --(SO)-- or --(SO.sub.2)-- wherein R.sup.6 is hydrogen or an
alkyl group having from 1 to 5 carbon atoms, and R.sup.7 is
hydrogen or an organic moiety having from 1 to 20 carbon atoms.
13. The gas hydrate inhibitor composition according to claim 1,
wherein the structure of the linking moiety L corresponds to one
out of formulae (2) to (12b)
--C(.dbd.O)--N(R.sup.6)--(CH.sub.2).sub.t-- (2)
--N(R.sup.7)--C(.dbd.O)--(CH.sub.2).sub.t-- (3)
--N(R.sup.7)--(CH.sub.2).sub.2--C(.dbd.O)--NH--(CH.sub.2).sub.t--
(4)
--N(R.sup.7)--C(.dbd.O)--(CH.sub.2).sub.2--N(R.sup.6)--(CH.sub.2).sub.t--
(5) --CH(OH)--CH.sub.2--N(R.sup.6)--(CH.sub.2).sub.t-- (6)
--CH(COOH)--CH.sub.2--C(.dbd.O)--N(R.sup.6)--(CH.sub.2).sub.t--
(7a)
--CH(CH.sub.2--COOH)--C(.dbd.O)--N(R.sup.6)--(CH.sub.2).sub.t--
(7b) ##STR00011##
--CH(COOH)--CH.sub.2--C(.dbd.O)-[0-(CH.sub.2).sub.t].sub.v-- (8a)
--CH(CH.sub.2--COOH)--C(.dbd.O)[O--(CH.sub.2).sub.t].sub.v-- (8b)
--N(R.sup.7)--C(.dbd.O)--(CH.sub.2).sub.2--C(.dbd.O)--N(R.sup.6)--(CH.sub-
.2).sub.t-- (9)
--N(R.sup.7)--C(.dbd.O)--CH.sub.2--CH(OH)--C(.dbd.O)--N(R.sup.6)--(CH.sub-
.2).sub.t-- (10a)
--N(R.sup.7)--C(.dbd.O)--CH(OH)--CH.sub.2--C(.dbd.O)--N(R.sup.6)--(CH.sub-
.2).sub.t-- (10b)
--N(R.sup.7)--C(.dbd.O)--CH(OH)--CH(OH)--C(.dbd.O)--N(R.sup.6)--(CH.sub.2-
).sub.t-- (11)
--N(R.sup.7)--C(.dbd.O)--C(OH)(CH.sub.2COOH)--CH.sub.2--C(.dbd.O)--N(R.su-
p.6)--(CH.sub.2).sub.t-- (12a)
--N(R.sup.7)--C(.dbd.O)--CH.sub.2--C(OH)(CH(COOH)--C(.dbd.O)--N(R.sup.6)--
-(CH.sub.2).sub.t-- (12b) wherein R.sup.6 is hydrogen or an alkyl
group having from 1 to 5 carbon atoms, and R.sup.7 is hydrogen or
an organic moiety having from 1 to 20 carbon atoms.
14. The gas hydrate inhibitor composition according to claim 1,
wherein the amphiphile (A) is an amido amine according to the
general formula (13) ##STR00012## wherein R.sup.1, R.sup.2,
R.sup.3, R.sup.5 and X.sup.- have the general meanings given above
for formula (1) and its preferred embodiments; R.sup.4 is selected
from the group consisting of --(CH.sub.2).sub.t--,
--[(CH.sub.2--CHR.sup.10).sub.s]--,
--(CH.sub.2--CHR.sup.10O).sub.u--(CH.sub.2).sub.t-- and
combinations thereof; R.sup.6 is hydrogen or an alkyl group having
from 1 to 5 carbon atoms; R.sup.7 is hydrogen or an organic moiety
having from 1 to 20 carbon atoms; R.sup.8 is present or not as
hydrogen or an alkyl group having from 1 to 5 carbon atoms; with
the proviso that when m=0, R.sup.8 is not present; R.sup.9 is
present or not as hydrogen or an alkyl group having from 1 to 5
carbon atoms; with the proviso that when o=0, R.sup.9 is not
present; R.sup.10 is an alkyl group having 1 to 4 carbon atoms; m
is 0 or 2, n is 0 or 1, o is 0 or 2, p is 0 or an integer between 1
and 5; q is 0 or an integer between 1 and 6, but is not more than
the sum of n+p n+p is an integer between 1 and 6; s is 1, 2 or 3; t
is 2, 3 or 4; and u is an integer between 1 and 100.
15. The gas hydrate inhibitor composition according to claim 1,
wherein the amphiphile (A) is an amido amine according to the
general formula (14) ##STR00013## wherein R.sup.1, R.sup.2,
R.sup.3, R.sup.5 and X.sup.- have the general meanings given above;
R.sup.4 is selected from --(CH.sub.2).sub.t-- and
--[(CH.sub.2--CHR.sup.10).sub.s]--; R.sup.6 is hydrogen or an alkyl
group having from 1 to 5 carbon atoms; R.sup.10 is an alkyl group
having 1 to 4 carbon atoms; p is an integer between 1 and 5; s is
1, 2 or 3; t is 2, 3 or 4; q is 0 when R.sup.3 is absent, or q is 1
when R.sup.3 is present.
16. The gas hydrate inhibitor composition according to claim 15,
wherein the compound according to formula (14) is the reaction
product of an N,N-dialkylaminoalkylamine of formula
HN(R.sup.6)--R.sup.4--N(R.sup.1)(R.sup.2) with a fatty acid, a
fatty acid ester or a glyceride.
17. The gas hydrate inhibitor composition according to claim 15,
wherein the compound according to formula (14) includes a product
prepared by the reaction of an amine selected from
(3-dialkylamino)propylamine and (3-dialkylamino)ethylamine with a
vegetable oil or tallow oil, followed by either neutralization with
an acid selected from mineral acids and carboxylic acids having
from 1 to 20 carbon atoms, or followed by quaternization with an
alkylating agent selected from an organic halide, dimethyl sulfate,
diethyl sulfate and C.sub.2-C.sub.4 alkylene oxides, and wherein
the dialkyl amino group of the (3-dialkylamino)propylamine includes
two alkyl groups independently selected from the group consisting
of methyl, ethyl, propyl, butyl, and combinations thereof or,
wherein R.sup.1 and R.sup.2 together with the nitrogen atom to
which they are attached form a substituted or unsubstituted
heterocyclic group having 5 or 6 atoms in the ring.
18. The gas hydrate inhibitor composition according to claim 1,
wherein the amphiphile (A) is an amido amine according to one or
more of formulae (15), (16) and/or (17): ##STR00014## wherein
R.sup.1, R.sup.2, R.sup.3, R.sup.5 and X.sup.- have the meanings
given above for formula (1); R.sup.4 is --(CH.sub.2).sub.t--;
R.sup.6 is hydrogen or an alkyl group having from 1 to 5 carbon
atoms; R.sup.7 is hydrogen or an organic moiety having 1 to 20
carbon atoms; R.sup.8 and R.sup.9 independently is present or not
as hydrogen or an alkyl group having from 1 to 5 carbon atoms; q is
0 when R.sup.3, R.sup.8 and R.sup.9 are absent; and q is 1, 2 or 3
depending on the presence of one or more of R.sup.3, R.sup.8 and/or
R.sup.9; and t is 2, 3 or 4.
19. The gas hydrate inhibitor composition according to claim 1,
wherein the nonionic surfactant (B) is an N-acylated
polyhydroxyalkylamine of general formula (19) ##STR00015## wherein
Z is the polyhydroxyalkyl radical of a monosaccharide or
oligosaccharide; R.sup.11 is an alkyl or alkenyl group having 8 to
18 carbon atoms; and R.sup.12 is an alkyl group having from 1 to 5
carbon atoms.
20. The gas hydrate inhibitor composition according to claim 1,
wherein the nonionic surfactant (B) comprises an
N-alkyl-N-acylglucamine of general formula (21) ##STR00016##
wherein R.sup.11 is an alkyl or alkenyl group having 8 to 18 carbon
atoms; and R.sup.12 is an alkyl group having from 1 to 5 carbon
atoms.
21. The gas hydrate inhibitor composition according to claim 1,
wherein the nonionic surfactant (B) comprises at least one cyclic
N-Alkyl-N-acylglucamine selected from the formulae (22), (23),
and/or (24) ##STR00017## wherein R.sup.11 is an alkyl or alkenyl
group having 8 to 18 carbon atoms; and R.sup.12 is an alkyl group
having from 1 to 5 carbon atoms.
22. The gas hydrate inhibitor composition according to claim 1,
wherein R.sup.12 is methyl.
23. The gas hydrate inhibitor composition according to claim 1,
wherein the portion of the nonionic surfactant (B) is between 10
and 85 wt.-%, based on the combined weights of (A) and (B).
24. The gas hydrate inhibitor composition according to claim 1,
wherein the weight ratio between amphiphile (A) and nonionic
surfactant (B) is between 20:1 and 1:20.
25. The gas hydrate inhibitor composition according to claim 1,
additionally containing up to 30 wt.-% of a further surfactant (C)
being different from (A) and (B), based on the combined masses of
(A) and (B).
26. The gas hydrate inhibitor composition according to claim 1,
containing 1 to 30 wt.-% of at least one further surfactant (C)
being different from (A) and (B), selected from the group
consisting of anionic, nonionic, amphoteric and/or cationic
surfactants.
27. The gas hydrate inhibitor composition according to claim 1,
wherein the composition further comprises at least one kinetic gas
hydrate inhibitor being different from (A), (B) and (C).
28. The gas hydrate inhibitor formulation, comprising the gas
hydrate inhibitor composition according to claim 1, and at least
one diluent.
29. The gas hydrate inhibitor formulation according to claim 28,
wherein the diluent is selected from monohydric lower alcohols,
glycols, ether solvents, ketonic solvents, esters, acetonitrile,
water, and aliphatic, aromatic, alkylaromatic solvents, and
mixtures thereof.
30. The gas hydrate inhibitor formulation according to claim 28,
wherein the diluent is present in the inhibitor formulation in the
range from 0.1 wt.-% to 95 wt.-%, based on the combined weight of
(A), (B), optionally (C), and the diluent.
31. A method for inhibiting the formation of gas hydrate
agglomerates and/or plugs, the method comprising bringing a system
containing hydrocarbons and water susceptible to gas hydrate
formation into contact with the composition comprising A) from 5 to
95 weight-% of an amphiphile having a hydrophobic tail linked to a
hydrophilic head group by a linking moiety, the amphiphile having
the general formula (1)
[R.sup.5-L-N(R.sup.1)(R.sup.2)(R.sup.3)]+X.sup.- (1) wherein each
of R.sup.1 and R.sup.2 is independently an alkyl group having from
1 to 5 carbon atoms; or wherein the nitrogen atom and the R.sup.1
and R.sup.2 groups together form a substituted or unsubstituted
heterocyclic group; R.sup.3 is present or not as hydrogen or an
alkyl group having from 1 to 8 carbon atoms which optionally bears
a hydroxy group or a carboxy group in the 2-position; L is a
linking moiety comprising an optionally substituted hydrocarbyl
group having at least 2 adjacent carbon atoms, at least one
heteroatom selected from nitrogen and oxygen, and optionally one or
more further heteroatoms; R.sup.5 is a hydrocarbyl group having
from 6 to 22 carbon atoms; and X.sup.- is present as an anion when
R.sup.3 is present; and B) from 5 to 95 weight-% of a nonionic
surfactant which is selected from N-acylated
polyhydroxyalkylamines.
32. The method according to claim 31, wherein the pressure during
contacting is at or greater than atmospheric pressure.
33. The method according to claim 31, wherein the hydrocarbon is a
naturally produced gas with the major part of the gas being
C.sub.1-C.sub.5 hydrocarbons.
34. (canceled)
35. A method for improving the hydrate inhibitor performance of an
amphiphile (A) having the general formula (1)
[R.sup.5-L-N(R.sup.1)(R.sup.2)(R.sup.3)]+X.sup.- (1) wherein each
of R.sup.1 and R.sup.2 is independently an alkyl group having from
1 to 5 carbon atoms; or wherein the nitrogen atom and the R.sup.1
and R.sup.2 groups together form a substituted or unsubstituted
heterocyclic group; R.sup.3 is present or not as hydrogen or an
alkyl group having from 1 to 8 carbon atoms which optionally bears
a hydroxy group or a carboxy group in the 2-position; L is a
linking moiety comprising an optionally substituted hydrocarbyl
group having at least 2 adjacent carbon atoms, at least one
heteroatom selected from nitrogen and oxygen, and optionally one or
more further heteroatoms; R.sup.5 is a hydrocarbyl group having
from 6 to 22 carbon atoms; and X.sup.- is present as an anion when
R.sup.3 is present; the method comprising the addition of a
nonionic surfactant (B) selected from N-alkyl-N-acylglucamines to
the amphiphile (A), wherein the nonionic surfactant is added to (A)
in an amount of 5 to 95 wt.-% in respect to the total amount of (A)
and (B).
36. (canceled)
37. A mixture of hydrocarbons and water comprising a composition
according to claim 1, wherein the mixture has a reduced tendency to
form hydrocarbon hydrate agglomerates under hydrate forming
conditions.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to co-pending U.S.
Provisional Patent Application No. 62/946,679, filed Dec. 11, 2019,
the entirety of which is hereby incorporated herein by
reference.
[0002] This invention relates to the prevention of gas hydrate
blockage in oil and natural gas pipelines containing low-boiling
point hydrocarbons and water. More specifically, the invention
relates to a method of controlling gas hydrate blockage through the
addition of a synergistically acting blend of chemical
compositions.
[0003] Gas hydrates are typically solids that may form in a fluid
that is flowing or is substantially stationary, under certain
temperature and pressure conditions. For example, gas hydrates may
form during hydrocarbon production from a subterranean formation,
in pipelines and other equipment during production operations.
Hydrates may impede or completely block flow of hydrocarbons or
other fluid flowing through such pipelines. These blockages not
only may decrease or stop production, potentially costing millions
of dollars in lost production, but also may be very difficult and
dangerous to mediate. Unless properly handled, gas hydrates may be
volatile and even explosive, potentially rupturing pipelines,
damaging equipment, endangering workers, and causing environmental
harm. Gas hydrates may form when water molecules become bonded
together after coming into contact with certain "guest" gas or
liquid molecules. Hydrogen bonding may cause the water molecules to
form a regular lattice structure, like a cage, that is stabilized
by the guest gas or liquid molecules entrapped within the lattice
structure. The resulting crystalline structure may precipitate as a
solid gas hydrate. Guest molecules can include any number of
molecules such as, for example, carbon dioxide hydrogen, and low
molecular weight hydrocarbons including methane, ethane, propane,
n-butane, iso-butane, n-pentane, iso-pentane, and the like, and
combinations of these gases as for example natural gas.
[0004] There are two basic techniques to overcome or control the
gas hydrate problems, namely thermodynamic and low dose hydrate
inhibitors (LDHIs). Thermodynamic hydrate inhibitors, such as
methanol or one of the glycols, have traditionally been used to
prevent these hydrate formations. These thermodynamic inhibitors
are effective at 5-50% (or higher) based on the amount of water. As
oil companies are exploring new production in deep waters, the
total gas/oil/water productions are also increasing. The use of
thermodynamic inhibitors is not viable in these applications due to
logistical constraints of supplying and pumping such vast
quantities of fluids to often remote locations.
[0005] LDHIs can overcome such logistical constraints. There are
two broad categories of LHDI: Kinetic Hydrate Inhibitors (KHIs) and
Anti-Agglomerants (AAs). Kinetic hydrate inhibitors have been
identified to prevent hydrate formation so that the fluids can be
pumped out before a catastrophic hydrate formation occurs. The
kinetic inhibitors prevent or delay hydrate crystal nucleation and
disrupt crystal growth. Kinetic hydrate inhibitors contain moieties
similar to gas molecules previously mentioned. It is believed that
kinetic inhibitors impede hydrate crystal growth by becoming
incorporated into the growing hydrate crystals, thereby disrupting
further hydrate crystal growth. The growing hydrate crystals can
complete a cage by combining with the partial hydrate-like cages
around the kinetic hydrate inhibitor moieties containing
hydrate-like groups. KHIs are effective with or without the
presence of a liquid hydrocarbon phase, but they are typically less
effective in preventing hydrate formation as the production
pressure increases. Examples of kinetic hydrate inhibitors include
poly(N-methylacrylamide), poly(N,N-dimethylacrylamide),
poly(N-ethylacrylamide), poly(N,N-diethylacrylamide),
poly(N-methyl-N-vinylacetamide), poly(2-ethyloxazoline),
poly(N-vinylpyrrolidone), poly(N-vinylcaprolactam), and copolymers
comprising the respective monomers.
[0006] Besides the kinetic hydrate inhibitors, there is a second
general type of LDHIs, the so-called anti-agglomerants. While KHIs
work by delaying or even preventing the growth of gas hydrate
crystals and may function as "anti-nucleators", anti-agglomerants
allow hydrates to form but disperse them in the form of fine
particles, known as a hydrate slurry. AAs prevent hydrates from
agglomeration and subsequently from accumulating into larger
aggregates capable of causing plugs. Often anti-agglomerants
prevent the once formed smaller gas hydrate crystals to adhere to
the pipe wall.
[0007] Unlike the kinetic hydrate inhibitors, anti-agglomerants are
effective only in the presence of an oil phase. The oil phase
provides a transport medium for the hydrates which are referred to
as hydrate slurries so that the overall viscosity of the medium is
kept low and can be transported along the pipeline. As such, the
hydrate crystals formed in the water-droplets are prevented from
agglomerating into a larger crystalline mass.
[0008] A group of chemicals which has proven to prevent
agglomeration of hydrate crystals are surface active substances as
for example non-ionic amphiphilic compounds and quaternary ammonium
salts having at least three alkyl groups with four or five carbon
atoms and a long chain hydrocarbon group containing 8-20 atoms, as
for example tributylhexadecylphosphonium bromide and
tributylhexadecylammonium bromide.
[0009] Accordingly, U.S. Pat. No. 4,915,176 disclose the use
amphiphilic compounds in general and U.S. Pat. Nos. 4,973,775 and
5,244,878 the use of especially nonionic amphiphilic compounds
comprising a hydrophilic part comprising alkylene oxide, hydroxyl
or alkylene amine groups, an oleophilic part comprising a
hydrocarbon chain derived from an alcohol, a fatty acid, an
alkylated derivative of phenol or an isobutene- or butene-based
polyolefin, and a bond between the hydrophilic and oleophilic parts
which can be, for example, an ether, ester or amide bridge to delay
the formation and/or reduce the agglomeration tendency of hydrates.
Among the nonionic amphiphilic compounds with an ether bridge,
oxyethylated fatty alcohols, oxyethylated alkylphenols,
oxyethylated and/or oxypropylated derivatives and ethers of sugars
are cited. The amphiphilic compounds exemplified are preferably
alkanolamide compounds (U.S. Pat. No. 4,973,775) respectively
polyols partially or fully esterified with fatty acids as for
example sorbitan monolaurate and its ethoxylates (U.S. Pat. No.
5,244,878).
[0010] Furthermore, U.S. Pat. No. 5,460,728 teaches a method for
inhibiting the formation of hydrates, the method including the
addition of alkylated ammonium, phosphonium or sulphonium compounds
having three or four alkyl groups in their molecule, at least three
of which are independently chosen from the group of normal or
branched alkyls having at least four and preferably four to six
carbon atoms to a stream containing low-boiling hydrocarbons and
water. Examples for suited compounds are tetrapentylammonium
bromide, tributylhexadecylphosphonium bromide and
tributyldecylammonium bromide.
[0011] CN 105733539 discloses the use of a composition comprising a
polyalcohol nonionic surfactant and a quaternary ammonium salt as
gas hydrate anti-agglomerant. The exemplified polyalcohol nonionic
surfactants are esters of sorbitol with fatty acids; the
exemplified quaternary ammonium compounds include
dodecyltrimethylammonium chloride, tetradecyltrimethylammonium
chloride and didecyldimethylammonium chloride with
tetrabutylammonium bromide being especially preferred.]
[0012] Another group of chemicals which has proven to efficiently
prevent agglomeration of hydrate crystals are amphiphilic
carboxylic acid derivatives comprising a lipophilic alkyl chain and
a tertiary amino group respectively an ammonium group.
[0013] WO 2012/082815 discloses compositions comprising beta-amino
ester surfactants and their ammonium salts as anti-agglomerants.
The beta-amino ester surfactants can be made by nucleophilic
addition of a 3-(dialkylamino)-propylamine to an acrylic acid ester
and subsequent neutralization of the amino group with a mineral
acid or a carboxylic acid, respectively quaternization of the amino
group.
[0014] WO 2013/089802 discloses compositions comprising salts of
beta-amino amide surfactants and their use as anti-agglomerants to
reduce or inhibit the formation of gas hydrates. The beta-amino
amides can be made by nucleophilic addition of an amine as for
example dibutyl amine to acrylic acid followed by amidation with a
fatty amine and subsequent neutralization of the amino group with a
mineral acid or a carboxylic acid, respectively quaternization.
[0015] WO 2016/069987 discloses hydrate inhibitor compositions
comprising zwitterionic or cationic ammonium surfactants. The
hydrate inhibitors may be made by reaction of acrylic acid with a
fatty amine and a N,N-dialkylaminoalkyl amine, followed by
quaternization or neutralization of the amino group.
[0016] WO 2017/184115 discloses compositions and methods of using
these compositions to inhibit of the formation of gas hydrate
agglomerates wherein the compositions may be characterized as
reaction products of: (1) a dialkylaminoalkyl amine and (2) a first
intermediate formed as the reaction product of one or more
unsaturated carboxylic acids or esters containing an alkene chain
(e.g., acrylates) and an amine that may further be reacted with (3)
one or more alkylating agents.
[0017] U.S. Pat. No. 7,381,689 teaches a method and an amide
composition used therein for inhibiting, retarding, mitigating,
reducing, controlling and/or delaying formation of hydrocarbon
hydrates or agglomerants of hydrates in a process stream. The
method comprises the addition of at least one amide compound into
the process stream, where the compound may be mixed with another
compound selected from amino alcohols, esters, quaternary ammonium,
phosphonium or sulphonium salts, betaines, amine oxides, other
amides, simple amine salts, and combinations thereof.
[0018] US 2018/346790 discloses a process for limiting the
formation and/or agglomeration of gas hydrates, using a composition
comprising one or more carboxylic amino acids of particular
structure (e.g. N-cocoyl-.beta.-aminopropanoic,
N-cocoyl-.beta.-aminodipropanoic) and one or more nonionic
surfactants. The nonionic surfactant(s) are chosen from sorbitan
esters, alkoxylated sorbitan esters, alkoxylated fatty acids, and
alkoxylated fatty alcohols, each of the alkoxylated species listed
advantageously comprising from 1 to 25 oxyethylene (OE) units.
Allegedly, this combination of an amphoteric surfactant with a
nonionic surfactant prevents or limits the agglomeration of gas
hydrates and remains efficient for subcooling values of less than
or equal to -20.degree. C.
[0019] However, there remains a need for hydrate inhibitors that
effectively prevent agglomeration of hydrates in oil and gas
transportation and handling processes. It would be desirable to
identify hydrate inhibitors that are effective at lower dosages,
and that are especially effective at high pressures and/or low
temperatures such as those encountered in deep water production
and/or at high water cuts.
[0020] Furthermore, as most gas hydrate inhibitors are amphiphilic
substances, they have potential to emulsify oil in the co-produced
water which often has a negative impact on the operational system
to which they are applied. Accordingly, emulsion tendency is an
important secondary property, because the co-produced fluids (oil
to be sold and water to be disposed of) need to separate quickly
once topside, typically within 30 minutes, if not preferably less
time as for example within 10 and even more preferred within 5
minutes. Separation speed is critical because if it is not fast
enough, it may cause production to be choked back to allow time for
the separation to occur; oil wetness must be minimized because
there are typically limits to the amount of water that can remain
in the salable oil, and finally, the produced water has a low limit
to the amount of oil that can remain in it, in large part due to
its eventual disposal overboard, back into the environment.
[0021] Surprisingly, it has been found that the performance of a
gas hydrate inhibitor composition comprising an amphiphile which
has a N,N-dialkylamino group linked to a hydrophobic tail via a
linking moiety which is an optionally substituted hydrocarbyl group
comprising at least one nitrogen and/or oxygen atom, will be
synergistically enhanced in its performance as a gas hydrate
inhibitor when used together with a nonionic surfactant.
Accordingly, such combination allows for reduced overall treat
rates. Additionally, such combination provides further unexpected
performance benefits which also have a beneficial effect on the
operational system to which the gas hydrate inhibitors are applied,
including less issues caused by foam formation and produced water
quality. Specifically, such combination was found to result in
improved water drop properties, including a reduction of the time
to achieve significant water drop and a reduction of the absolute
amount of water remaining emulsified into the co-produced oil. This
reduces the need for further chemical treatment to separate
emulsified water out of the oil prior to its export in the limited
amount of time available once fluids are topside and need to be
processed and often makes further chemical treatment unnecessary.
Furthermore, it has been found that such combination is able to
work at higher water cuts than previously possible with single use
of hydrate inhibitor, i.e. the combination of the amphiphile with
the nonionic surfactant extends the range of water cuts that are
possible to be treated for hydrate formation.
[0022] In a first aspect, the instant invention provides a gas
hydrate inhibitor composition comprising [0023] A) from 5 to 95
weight-% of an amphiphile having a hydrophobic tail linked to a
hydrophilic head group by a linking moiety, the amphiphile having
the general formula (1)
[0023] [R.sup.5-L-N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.- (1)
[0024] wherein [0025] each of R.sup.1 and R.sup.2 is independently
an alkyl group having from 1 to 5 carbon atoms; or wherein the
nitrogen atom and the R.sup.1 and R.sup.2 groups together form a
substituted or unsubstituted heterocyclic group; [0026] R.sup.3 is
present or not as hydrogen or an alkyl group having from 1 to 8
carbon atoms which optionally bears a hydroxy group or a carboxy
group in the 2-position; [0027] L is a linking moiety comprising an
optionally substituted hydrocarbyl group having at least 2 adjacent
carbon atoms, at least one heteroatom selected from nitrogen and
oxygen, and optionally one or more further heteroatoms; [0028]
R.sup.5 is a hydrocarbyl group having from 6 to 22 carbon atoms;
and [0029] X.sup.- is present as an anion when R.sup.3 is present;
[0030] B) from 5 to 95 weight-% of a nonionic surfactant which is
an N-acylated polyhydroxyalkylamine.
[0031] In a second aspect, the instant invention provides a method
for inhibiting the formation of gas hydrate agglomerates and/or
plugs, the method comprising bringing a system containing
hydrocarbons and water susceptible to gas hydrate formation in
contact with the composition according to the first aspect of the
invention.
[0032] In a third aspect, the instant invention provides the use of
the composition according to the first aspect of the invention for
inhibiting the formation of gas hydrate agglomerates and/or plugs
in a system containing hydrocarbons and water.
[0033] In a fourth aspect, the instant invention provides a method
for improving the hydrate inhibitor performance of an amphiphile
(A) having the general formula (1) given above, the method
comprising the addition of a nonionic surfactant (B) which is
selected from N-acylated polyhydroxyalkylamines to the amphiphile
(A).
[0034] In a fifth aspect, the instant invention provides the use of
a nonionic surfactant (B) which is selected from N-acylated
polyhydroxyalkylamines for improving the hydrate inhibitor
performance of an amphiphile (A) having the general formula (1)
above.
[0035] In a sixth aspect, the instant invention provides a mixture
of hydrocarbons and water comprising the composition of the first
aspect of the invention, wherein the mixture has a reduced tendency
to form hydrocarbon hydrate agglomerates under hydrate forming
conditions.
[0036] Besides amphiphile (A) and nonionic surfactant (B), the gas
hydrate inhibitor composition according to the invention may
optionally contain up to 30 wt.-% of a further surfactant (C) which
is different from A) and B).
[0037] The term hydrate inhibitor performance includes the gas
hydrate composition's capability to provide for enhanced
anti-agglomeration and/or enhanced inhibition, retardation,
mitigation, reduction, control, delay, and/or the like of
agglomeration of hydrates and/or hydrate-forming compounds. In
certain embodiments, agglomeration of hydrates and/or
hydrate-forming compounds (and the like) may be reduced and/or
inhibited to a greater degree than that achieved using the hydrate
inhibitor components individually.
[0038] Synergistically improved hydrate inhibition means that the
hydrate inhibitor performance of the combination of components A
and B is greater than the sum of the action of each of the
components when used alone. This means that either the hydrate
inhibitor performance obtained with the combination of the
compounds (A) and (B) is greater than expected from the sum of the
individual components when used alone; or, alternatively, a
predetermined hydrate inhibitor performance is achieved with a
lower dose rate of the combination of components (A) and (B) than
with each of the individual components when used alone. Whether or
not there is a synergy between components A) and B) is determined
by the reduced dose rate required to prevent gas hydrate
agglomeration over the dose rate required of each of the individual
components. Often the reduction of dosage rate is between 5 and 70
wt.-%, preferably between 10 and 40 wt.-% and most preferably
between 20 and 35 wt.-% as for example between 5 and 40 wt.-%, or
between 5 and 35 wt.-%, or between 10 and 50 wt.-%, or between 10
and 35 wt.-%, or between 20 and 70 wt.-%, or between 20 and 40
wt.-%. Alternatively, or in addition to the above, a synergistic
effect between components A) and B) can be determined by comparison
of secondary properties such as emulsion tendency, and more
specifically of the water drop properties of the co-produced
mixture of oil and water. The combination of components A) and B)
results in a faster and more complete separation of water than
obtained when one of the components is used alone.
[0039] The terms "hydrate" and "gas hydrate" are used
interchangeably and refer to a gaseous mixture in a water
clathrate; i.e. they refer to a solid hydrogen-bonded network of
water molecules encapsulating gas molecules to form a cage-like
structure or hydrate which is also known as clathrate. Especially,
the terms refer to hydrates formed by low molecular weight
hydrocarbons. Similarly, the terms "hydrate inhibitor" and "gas
hydrate inhibitor" are used interchangeably, referring to additives
inhibiting, retarding, mitigating, reducing, controlling and/or
delaying formation of hydrates and/or agglomerates of hydrates
and/or plugs.
[0040] Amphiphile (A)
[0041] Component (A) of the hydrate inhibitor composition according
to the invention contains an amphiphile having the general formula
(1) wherein a lipophilic tail R.sup.5 which is a hydrocarbyl group
having 6 to 22 carbon atoms is linked by a linking moiety L to a
hydrophilic head group which comprises a N,N-dialkylamino group
--N(R.sup.1)(R.sup.2) wherein R.sup.1 and R.sup.2 are
C.sub.1-C.sub.5-alkyl groups, or together with the nitrogen atom to
which they are attached form a substituted or unsubstituted
heterocyclic group, and wherein the N,N-dialkylamino group may be
in the form of an ammonium compound. As used herein, the term
"linking moiety" refers to any portion of the hydrate inhibitor
component (A) that provides spacing between the lipophilic tail
R.sup.5 and the hydrophilic head group
--[N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.-.
[0042] Preferably, the lipophilic tail R.sup.5 of the amphiphile
(A) is an alkyl or alkenyl group having 6 to 22 carbon atoms and
especially preferred having 8 to 20 carbon atoms, as for example 6
to 18 carbon atoms, or 8 to 22 carbon atoms. Preferred alkyl and
alkenyl groups may be linear, branched or cyclic and/or any
combination thereof. Preferred alkyl and alkenyl residues R.sup.5
are octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl,
hexadecyl, octadecyl, eicosyl, dodecenyl, tetradecenyl,
hexadecenyl, octadecenyl, eicosenyl, and their mixtures. The alkyl-
and alkenyl groups R.sup.5 may be of natural or synthetic origin.
In certain embodiments, the amphiphile may comprise one or more
further lipophilic tails, for example alkyl or alkenyl residues
stemming from substituents of the linking moiety L.
[0043] Preferred substituents R.sup.1 and R.sup.2 are alkyl
residues having from 3 to 5 carbon atoms and especially preferred
are those having 4 carbon atoms. The alkyl residues R.sup.1 and
R.sup.2 may be linear, or when they have at least three carbon
atoms they may be branched. Preferably they are linear. Examples
for alkyl residues R.sup.1 and R.sup.2 are methyl, ethyl, n-propyl,
iso-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl and
iso-pentyl. Preferred among those are n-propyl, iso-propyl,
n-butyl, iso-butyl, tert-butyl, n-pentyl and iso-pentyl.
Particularly preferred are n-butyl, iso-butyl, tert-butyl. The
alkyl residues R.sup.1 and R.sup.2 may be the same or they may be
different. Preferably, they are the same. In an especially
preferred embodiment, the polar head group is a N,N-dibutylamino
group.
[0044] The nitrogen atom, together with R.sup.1 and R.sup.2, may
form a cycle. When the nitrogen atom, together with R.sup.1 and
R.sup.2 forms a substituted or unsubstituted heterocyclic group,
the group can be considered a "nitrogen-containing heterocycle".
The nitrogen-containing heterocycle can denote optionally
substituted, fully saturated or unsaturated, monocyclic or
bicyclic, aromatic or nonaromatic groups having at least one
nitrogen atom in at least one ring, and preferably 5 or 6 atoms in
each ring. The nitrogen-containing heterocycle can also contain 1
or 2 oxygen atoms or 1 or 2 sulfur atoms in the ring. Exemplary
nitrogen-containing heterocycles include pyrrole, pyrroline,
pyrrolidine, piperidine, pyrazole, pyrazoline, pyrazolidine,
imidazole, imidazoline, imidazolidine, triazole, isoxazole,
isoxazoline, isoxazolidine, oxazole, oxazoline, oxazolidine,
thiazole, isothiazole, oxadiazole, oxatriazole, dioxazole,
oxathiazole, pyridine, pyridazine, pyrimidine, pyrazine,
piperazine, triazine, oxazine, oxathiazine, oxazine, isoxazine,
oxadiazine, morpholine, azepane, azepine, caprolactam, or
quinoline. When substituted, exemplary substituents include one or
more of the following groups: C.sub.1-C.sub.20 alkyl,
C.sub.2-C.sub.20 alkenyl, aryl, aralkyl, hydroxy, acyl, acyloxy,
alkoxy, alkenoxy, aryloxy, halogen, amino, nitro, cyano, esters and
ethers.
[0045] In a first preferred embodiment, the polar head group of the
amphiphile (A) according to formula (1) is a tertiary amino group
having, besides the bond to the linking moiety, substituents
R.sup.1 and R.sup.2 while R.sup.3 and X.sup.- are absent. In this
embodiment amphiphile (A) is an amine of formula (1a)
R.sup.5-L-N(R.sup.1)(R.sup.2) (1a)
[0046] wherein L, R.sup.1, R.sup.2 and R.sup.5 have the meanings
given above.
[0047] In a second preferred embodiment, the polar head group of
the amphiphile (A) according to formula (1) is an ammonium compound
wherein R.sup.3 and X.sup.- are present. In this embodiment,
amphiphile (A) is an ammonium compound of formula (1b)
[R.sup.5-L-N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.- (1b)
[0048] wherein
[0049] L, R.sup.1, R.sup.2 and R.sup.5 have the meanings given
above;
[0050] R.sup.3 is hydrogen or an alkyl group having from 1 to 8
carbon atoms which optionally bears a hydroxy group or a carboxy
group in the 2-position; and
[0051] X.sup.- is an anion.
[0052] In a preferred embodiment, R.sup.3 is hydrogen. Such
ammonium salt can be obtained by reaction of the above described
tertiary amino group --N(R.sup.1)(R.sup.2) of formula (1a) with an
acid. The acid may be organic or inorganic. Preferred inorganic
acids are halide acids like HCl, HBr and HI; sulfuric acid,
phosphoric acid, phosphorous acid, nitric acid, or a combination
thereof. Preferred organic acids are carboxylic acids, sulfonic
acids and phosphonic acids, as for example formic acid, acetic
acid, propionic acid, butyric acid, acrylic acid, methacrylic acid,
glycolic acid, pivalic acid, malic acid, maleic acid, succinic
acid, thioglycolic acid, methane sulfonic acid, p-toluene sulfonic
acid, the like, and any combination thereof.
[0053] Preferably, X.sup.- is selected from hydroxide, carboxylate,
halide, sulphate, nitrite, nitrate, organic sulfonate, phosphate,
organic phosphonate, and combinations thereof. Suitable halide ions
include, without limitation, fluoride, chloride, bromide, iodide,
and combinations thereof. Suitable carboxylates include anions
stemming from carboxylic acids having from 1 to 20 carbon atoms,
more preferably having from 2 to 12 carbon atoms and especially
preferred having from 3 to 6 carbon atoms as for example having
from 1 to 12, or from 1 to 6, or from 2 to 20, or from 2 to 6, or
from 3 to 20, or from 3 to 12 carbon atoms. In a preferred
embodiment, the carboxylic acid is aliphatic. Preferred aliphatic
carboxylic acids may be linear or branched; they may be saturated
or unsaturated. Examples for especially preferred carboxylates are
formate, acetate, propionate, butyrate, pentanoate, hexanoate,
acrylate, methacrylate, glycolate, malonate, succinate,
trifluoroacetate, and mixtures thereof. Especially preferred the
anion X.sup.- is selected from carboxylate, halide, acrylate,
methacrylate, and combinations thereof; most preferred X.sup.- is
acrylate. In an especially preferred embodiment, X.sup.- is the
anion of the acid used for protonation of the amino group.
[0054] In a further preferred embodiment, R.sup.3 is an alkyl group
having from 1 to 8 carbon atoms. In some embodiments, when R.sup.3
has 2 or more carbon atoms, R.sup.3 may be substituted by a hydroxy
group or with a carboxyl group in the 2-position of the alkyl
group. Such quaternary ammonium compound wherein R.sup.3 is an
alkyl group can be obtained by reaction of the above described
tertiary amino group --N(R.sup.1)(R.sup.2) of formula (1a) with an
alkylating agent. The quaternizing agent may include alkyl halides,
alkyl sulfates, oxalates, carbonates, hydrocarbyl epoxides and
mixtures thereof. In some embodiments, the quaternizing agent may
be a sulfate, such as dimethyl sulfate. In some embodiments, the
quaternizing agent may be a halide, such as CH.sub.3Cl. In some
embodiments, the quaternizing agent may be a carbonate, such as
dimethyl carbonate. In some embodiments, the quaternizing agent may
be an epoxide, such as a hydrocarbyl epoxide, such as, for example,
ethylene oxide, propylene oxide, butylene oxide, and the like. In
some embodiments, the quaternizing agent may be acrylic acid or
methacrylic acid. Especially preferred alkylating agents include
methyl chloride, methyl bromide, methyl iodide, ethyl chloride,
ethyl bromide, ethyl iodide, dimethyl sulfate, diethyl sulfate and
any combination thereof. In a preferred embodiment, X.sup.- is the
anion formed during reaction of the alkylating agent with the amino
group as for example chloride, bromide, iodide, methosulfate,
ethosulfate, the like and any combination thereof. In an especially
preferred embodiment, R.sup.3 is a methyl group.
[0055] The linking moiety L is defined as the part of the
amphiphile (A) according to formula (1) which connects the
hydrophilic head group --N(R.sup.1)(R.sup.2), respectively
--[N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.-, with the lipophilic
tail R.sup.5. The linking moiety L contains a connecting chain
which constitutes the direct connection between the hydrophilic
head group --N(R.sup.1)(R.sup.2), respectively
--[N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.-, and the lipophilic
tail R.sup.5 and which may have substituents attached to it. The
connecting chain is made from carbon atoms, at least one heteroatom
selected from oxygen and nitrogen and optionally one or more
further heteroatoms. The atoms forming the connecting chain will be
referred to as linking elements in the following. For the sake of
clarity, the connecting chain does not include any substituents. In
case the linking moiety L is a hydrocarbyl group having at least 2
adjacent carbon atoms, at least one heteroatom selected from
nitrogen and oxygen, optionally one or more further heteroatoms and
does not contain any substituents, the linking moiety L and the
connecting chain are the same.
[0056] The linking moiety L may instead or in addition be
characterized as an optionally substituted heteroaliphatic chain.
Heteroaliphatic chain means that the link between lipophilic tail
R.sup.5 and hydrophilic head group --N(R.sup.1)(R.sup.2),
respectively --[N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.-
comprises a linear or branched chain made from carbon atoms which
is interrupted by at least one heteroatom selected from oxygen and
nitrogen and optionally one or more further heteroatoms selected
from nitrogen, oxygen, phosphorous, and sulfur. In a preferred
embodiment, at least one of the one or more further heteroatoms
interrupting the optionally substituted heteroaliphatic chain is a
nitrogen or an oxygen atom.
[0057] The linking moiety L may have heteroatoms attached to one or
more of its carbon linking elements, but not more than one
heteroatom per carbon linking element.
[0058] Preferably, heteroatoms attached to the connecting chain are
part of a functional group as for example a hydroxy, a carbonyl or
a carboxymethyl group. Furthermore, alkyl groups and especially
alkyl groups having 1 to 6 carbon atoms may be attached to carbon
and/or nitrogen atoms of the connecting chain.
[0059] In a preferred embodiment, the connecting chain contains
from 4 to 20, more preferably 5 to 14 and especially preferred 6 to
10 linking elements, as for example from 4 to 14, or from 4 to 12,
or from 5 to 20, or from 5 to 12, or from 6 to 20, or from 6 to 14
linking elements. In a further preferred embodiment, the linking
moiety L has a total of from 5 to 100, more preferably from 6 to
50, and especially preferred of from 6 to 20 atoms (carbon and
hetero atoms, but excluding hydrogens), as for example from 5 to
50, or from 5 to 20, or from 6 to 100 atoms. For counting the
number of atoms in the linking moiety and likewise in the
connecting chain it is necessary to define the boundary between
R.sup.5 and the linking moiety L. Starting from the lipophilic tail
R.sup.5 which is a hydrocarbyl group not containing heteroatoms,
the linking moiety begins at the position where there is either the
first heteroatom or a carbon atom that is substituted with a group
comprising at least one heteroatom.
[0060] In some embodiments, the nitrogen atom being part of the
linking moiety is part of an amino, a polyamino, an ammonium, or a
polyammonium, an amide and/or an imide group. The further
heteroatom or heteroatoms which may be part of the connecting chain
may be part of an ether, a polyether, an amino, a polyamino, an
ammonium, or a polyammonium group. In further embodiments, such
further heteroatom(s) may be part of a functional group as for
example an ester, an amide and/or an imide group. In such
embodiments the carbon atom of the carbonyl group and the
heteroatom within the connecting chain both constitute members of
the heteroaliphatic chain. In an especially preferred embodiment,
the linking moiety contains at least one further nitrogen atom in
the form of an amine or amide group.
[0061] In some embodiments, one or more heteroatoms may be attached
to the connecting chain as a substituent as for example a hydroxy
group, an amino group, a carboxylic acid group or a carboxylate
group.
[0062] The connecting chain may instead or in addition be
characterized as a heteroaliphatic chain which can be saturated or
unsaturated, wherein one or more non-adjacent CH.sub.2 groups are
replaced by a heteroatom selected from nitrogen, oxygen, sulfur and
phosphorous. The heteroatom may be part of a functional group.
Preferred functional groups are selected from --C(.dbd.O)--O--,
--O--C(.dbd.O)--, --C(.dbd.O)--N(R.sup.6)--,
--N(R.sup.7)--C(.dbd.O), --N(R.sup.6)--, --(R.sup.7)N--, --O--,
--S--, --(SO)-- or --(SO.sub.2)--, wherein R.sup.6 is hydrogen or
an alkyl group having from 1 to 5 carbon atoms, more preferably
having 3 to 5 carbon atoms and especially preferred having 4 carbon
atoms and wherein amino groups may be in form of their ammonium
compound, and R.sup.7 is hydrogen or an organic moiety having from
1 to 20 carbon atoms. Especially preferred R.sup.7 is hydrogen or
an alkyl group having from 1 to 20 carbon atoms.
[0063] Accordingly, the connecting chain may comprise one or more
aliphatic groups having 2 to 10, preferably 3 to 6 and especially
preferred 2 to 4 adjacent carbon atoms, which are connected to each
other and/or the hydrophobic tail by a heteroatom or a functional
group comprising a heteroatom whereby at least one heteroatom is a
nitrogen or oxygen atom. Examples for preferred functional groups
are --C(.dbd.O)--O--, --O--C(.dbd.O)--, --C(.dbd.O)--N(R.sup.6)--,
--N(R.sup.7)--C(.dbd.O)--, --N(R.sup.6)--, --(R.sup.7)N--, --O--,
--S--, --(SO)-- and --(SO.sub.2)--, wherein R.sup.6 and R.sup.7
have the meanings given above. Preferred aliphatic groups are
alkylene groups as for example any one or more of ethylene,
propylene, butylene, pentylene, hexylene, heptylene, octylene,
nonylene, decylene. In an especially preferred embodiment, the
linking moiety comprises one or more hydrocarbyl segments each
having 2 to 4 carbon atoms wherein the segments are linked by a
heteroatom selected from O and N or by a functional group
comprising at least one of those heteroatoms. Preferred functional
groups are esters and amides with amides being especially
preferred.
[0064] In some preferred embodiments, the lipophilic tail R.sup.5
may be connected to the hydrophilic head group-N(R.sup.1)(R.sup.2),
respectively --[N(R.sup.1)(R.sup.2)(R.sup.3)].sup.+X.sup.- via a
linking moiety L selected from the chemical structures (2) to
(7):
--C(.dbd.O)--N(R.sup.6)--(CH.sub.2).sub.t-- (2)
--N(R.sup.7)--C(.dbd.O)--(CH.sub.2).sub.t-- (3)
--N(R.sup.7)--(CH.sub.2).sub.2--C(.dbd.O)--NH--(CH.sub.2).sub.t--
(4)
--N(R.sup.7)--C(.dbd.O)--(CH.sub.2).sub.2--N(R.sup.6)--(CH.sub.2).sub.t--
- (5)
--CH(OH)--CH.sub.2--N(R.sup.6)--(CH.sub.2).sub.t-- (6)
--CH(COOH)--CH.sub.2--C(.dbd.O)--N(R.sup.6)--(CH.sub.2).sub.t--
(7a)
--CH(CH.sub.2--COOH)--C(.dbd.O)--N(R.sup.6)--(CH.sub.2).sub.t--
(7b)
##STR00001##
--CH(COOH)--CH.sub.2--C(.dbd.O)[O--(CH.sub.2).sub.t].sub.v--
(8a)
--CH(CH.sub.2--COOH)--C(.dbd.O)[O--(CH.sub.2).sub.t].sub.v--
(8b)
--N(R.sup.7)--C(.dbd.O)--(CH.sub.2).sub.2--C(.dbd.O)--N(R.sup.6)--(CH.su-
b.2).sub.t-- (9)
--N(R.sup.7)--C(.dbd.O)--CH.sub.2--CH(OH)--C(.dbd.O)--N(R.sup.6)--(CH.su-
b.2).sub.t-- (10a)
--N(R.sup.7)--C(.dbd.O)--CH(OH)--CH.sub.2--C(.dbd.O)--N(R.sup.6)--(CH.su-
b.2).sub.t-- (10b)
--N(R.sup.7)--C(.dbd.O)--CH(OH)--CH(OH)--C(.dbd.O)--N(R.sup.6)--(CH.sub.-
2).sub.t-- (11)
--N(R.sup.7)--C(.dbd.O)--C(OH)(CH.sub.2COOH)--CH.sub.2--C(.dbd.O)--N(R.s-
up.6)--(CH.sub.2).sub.t-- (12a)
--N(R.sup.7)--C(.dbd.O)--CH.sub.2--C(OH)(CH(COOH)--C(.dbd.O)--N(R.sup.6)-
--(CH.sub.2).sub.t-- (12b)
[0065] wherein [0066] t is 2, 3 or 4; [0067] v is an integer
between 1 and 30 and preferably between 1 and 10; [0068] R.sup.6 is
hydrogen or an alkyl group having from 1 to 5 carbon atoms, more
preferably having 2 to 4 carbon atoms and especially preferred
having 4 carbon atoms; [0069] R.sup.7 is hydrogen or an organic
moiety having from 1 to 20 carbon atoms and more preferred hydrogen
or an alkyl group having from 1 to 20 carbon atoms; and
[0070] wherein amino groups may be in form of their ammonium
compound.
[0071] In a preferred embodiment of the instant invention, the
amphiphile (A) is an amido amine according to the general formula
(13)
##STR00002##
[0072] wherein [0073] R.sup.1, R.sup.2, R.sup.3, R.sup.5 and
X.sup.- have the general meanings given above for formula (1) and
its preferred embodiments; [0074] R.sup.4 is selected from
--(CH.sub.2).sub.t--, --[(CH.sub.2--CHR.sup.10).sub.s]--,
--(CH.sub.2--CHR.sup.10O).sub.u--(CH.sub.2).sub.t-- and
combinations thereof; [0075] R.sup.6 is hydrogen or an alkyl group
having from 1 to 5 carbon atoms, more preferably having 1 to 4
carbon atoms and especially preferred being hydrogen, a methyl or a
butyl group; [0076] R.sup.7 is hydrogen or an organic moiety having
from 1 to 20 carbon atoms and more preferred hydrogen or an alkyl
group having from 1 to 20 carbon atoms; [0077] R.sup.8 is present
or not as hydrogen or an alkyl group having from 1 to 5 carbon
atoms, more preferably having 1 to 4 carbon atoms and especially
preferred being a methyl or butyl group, with the proviso that when
m=0, R.sup.8 is not present; [0078] R.sup.9 is present or not as
hydrogen or an alkyl group having from 1 to 5 carbon atoms, more
preferably having 1 to 4 carbon atoms and especially preferred
being a methyl or butyl group, with the proviso that when o=0,
R.sup.9 is not present; [0079] R.sup.10 is an alkyl group having 1
to 4 carbon atoms; [0080] s is 1, 2 or 3; [0081] t is 2, 3 or 4;
[0082] u is an integer between 1 and 10 and preferably between 1
and 5; [0083] n is 0 or 1 [0084] m is 0 or 2 [0085] o is 0 or 2
[0086] p is 0 or an integer between 1 and 5; [0087] n+p is an
integer between 1 and 6 and preferably 1; and [0088] q is 0 or an
integer between 1 and 7, but not more than the sum of n+p+1.
[0089] In a preferred embodiment, the sum of m+o in formula 13 is
2. In a further preferred embodiment, m, n and o in formula 13 all
are 0.
[0090] The number of anions q depends on the presence of R.sup.3,
R.sup.8 and/or R.sup.9. For example, when R.sup.3, R.sup.8 and
R.sup.9 are not present, q is 0; when only one of R.sup.3, R.sup.8
and R.sup.9 is present, q is 1; when o is 2, m is 0 and R.sup.3 as
well as R.sup.9 in all units --N(R.sup.6)(R.sup.9)--R.sup.4-- are
present, q may be equal to p+1, i.e. it is an integer between 2 to
6, depending on the value of p.
[0091] In an especially preferred embodiment, the amphiphile (A) is
an amido amine according to the general formula (14)
##STR00003##
[0092] wherein [0093] R.sup.1, R.sup.2, R.sup.3, R.sup.5 and
X.sup.- have the general meanings given above; [0094] R.sup.4 is
selected from --(CH.sub.2).sub.t-- and
--[(CH.sub.2--CHR.sup.10).sub.s]-- and more preferably is
--(CH.sub.2).sub.t--; [0095] R.sup.6 is hydrogen or an alkyl group
having from 1 to 5 carbon atoms and more preferably is hydrogen;
[0096] R.sup.10 is an alkyl group having from 1 to 4 carbon atoms;
[0097] p is an integer between 1 and 5; [0098] s is 1, 2 or 3;
[0099] t is 2, 3 or 4 and most preferred t is 3; [0100] q is 0 when
R.sup.3 is absent, or q is 1 when R.sup.3 is present.
[0101] The embodiment of formula (14) can be derived from formula
(13) wherein m, n and o are all 0.
[0102] In a preferred embodiment, p in formula (9) is 1 or 2, and
especially preferred p is 1. In a further preferred embodiment,
R.sup.3 is hydrogen, and the anion X.sup.- is selected from
hydroxide, carboxylate, halide, sulphate, organic sulfonate, and
combinations thereof.
[0103] In some embodiments, the compound according to formula (14)
is the reaction product of an N,N-dialkylaminoalkylamine of formula
HN(R.sup.6)--R.sup.4--N(R.sup.1)(R.sup.2) with a fatty acid of
formula R.sup.5--COOH, an ester of a fatty acid of formula
R.sup.5--COOH with an alcohol having 1 to 4 carbon atoms, or a
fatty acid glyceride. Preferably, the fatty acid, fatty acid ester
or fatty acid glyceride is derived from a plant source or an animal
source selected from vegetable oils, as for example coconut oil, or
tallow oil and combinations thereof.
[0104] In another embodiment, the compound according to formula
(14) includes a product prepared by the reaction of an amine
selected from 3-(dialkylamino)propylamine and
2-(dialkylamino)ethylamine with vegetable oil or tallow oil
followed by neutralization with an acid or by quaternization with
an alkylating agent. Preferred acids are selected from mineral
acids and organic acids having from 1 to 20 carbon atoms, as for
example formic acid, acetic acid, chloroacetic acid, propionic
acid, acrylic acid, and methacrylic acid. Preferred alkylating
agents are selected from an organic halide, such as an alkyl
halide, having from 1 to 8 carbon atoms, dimethyl sulfate and
C.sub.2-C.sub.4 alkylene oxides. Preferably, the dialkylamino group
of the N,N-dialkylaminoalkylamine includes two alkyl groups
independently selected from methyl, ethyl, propyl or butyl, and
combinations thereof; or when R.sup.1 and R.sup.2 together with the
nitrogen atom to which they are attached form a substituted or
unsubstituted heterocyclic group having 5 or 6 atoms in the ring.
Examples for preferred N,N-dialkylaminoalkylamines are
N,N-dimethylaminoethylamine, N,N-dimethylaminopropylamine,
N,N-diethylaminoethylamine, N,N-diethylaminopropylamine,
N,N-dipropylaminoethylamine, N,N-dipropylaminopropylamine,
N,N-dibutylaminoethylamine, N,N-dibutylaminopropylamine,
N,N-dimethylaminopropylenediamine,
N,N-dipropylaminopropylenediamine,
N,N-dibutylaminopropylenediamine, N-(3-aminopropyl)pyrrolidine,
N-(3-aminopropyl)piperidine, and N-(3-aminopropyl)azepane.
[0105] In further especially preferred embodiments, the amphiphile
(A) is an amido amine according to one or more of formulae (15),
(16) and/or (17):
##STR00004##
[0106] wherein [0107] R.sup.1, R.sup.2, R.sup.3, R.sup.5 and
X.sup.- have the meanings given above for formula (1); [0108]
R.sup.4 is --(CH.sub.2).sub.t--; [0109] R.sup.6 is hydrogen or an
alkyl group having from 1 to 5 carbon atoms, more preferably having
2 to 4 carbon atoms and especially preferred being hydrogen, a
methyl or a butyl group; [0110] R.sup.7 is hydrogen or an organic
moiety having 1 to 20 carbon atoms and more preferred hydrogen or
an alkyl group having from 1 to 20 carbon atoms; [0111] R.sup.8 and
R.sup.9 independently are present or not as hydrogen or an alkyl
group having from 1 to 5 carbon atoms, more preferably having 2 to
4 carbon atoms and especially preferred being hydrogen, a methyl or
a butyl group. [0112] q is 0 when R.sup.3, R.sup.8 and R.sup.9 are
absent; and q is 1, 2 or 3 depending on the presence of one or more
of R.sup.3, R.sup.8 and R.sup.9; and [0113] t is 2, 3 or 4 and most
preferred t is 3.
[0114] For instance, in some embodiments, the amphiphile (A)
according to formula (16) may be characterized as the reaction
product of (i) a N,N-dialkylaminoalkylamine having the general
formula HN(R.sup.6)--R.sup.4--N(R.sup.1)(R.sup.2) and (ii) a first
intermediate formed as the reaction product of one or more
ethylenically unsaturated carboxylic acids or esters and an alkyl
amine HN(R.sup.5)(R.sup.7). The ethylenically unsaturated
carboxylic acids or esters may be an alkyl alkenoate (e.g., an
alkyl methacrylate, an alkyl acrylate (for example, methyl
acrylate)), an alkenoic acid (e.g., acrylic acid), and any
combination thereof. For example, cocoylamine or oleylamine can
first be reacted with methyl acrylate and the reaction product can
be further reacted with a N,N-dialkylaminoalkylamine as for example
N,N-dimethylaminopropylamine, N,N-dibutylaminopropylamine,
pyrrolidine or the like to form an amide.
[0115] In some embodiments, the amphiphile (A) according to
formulae (15) and (17) may be characterized as the reaction product
of: (i) an alkyl amine having the formula --N(R.sup.5)(R.sup.7) and
ii) a first intermediate formed as the reaction product of one or
more ethylenically unsaturated carboxylic acids or esters (e.g.,
acrylates, methacrylates (for example, methyl acrylate)) and a
N,N-dialkylamine having the general formula
H[N(R.sup.6)--R.sup.4].sub.p--N(R.sup.1)(R.sup.2). For example, a
secondary amine wherein p is 0 having the formula
HN(R.sup.1)(R.sup.2) as for example dimethylamine, dibutylamine, or
a N,N-dialkylaminoalkylamine wherein p is 1 having the formula
HN(R.sup.6)--R.sup.4--N(R.sup.1)(R.sup.2) as for example
N,N-dimethylaminopropylamine, N,N-dibutylaminopropylamine,
pyrrolidine or the like can be reacted with methyl acrylate. The so
formed intermediate reaction product can then be reacted with an
alkyl amine having the formula --N(R.sup.5)(R.sup.7) as for example
cocoylamine or oleylamine to form an amide.
[0116] Via both of the reaction pathways leading to amphiphiles (A)
according to formulae (15), (16) and (17), the lipophilic tail(s)
R.sup.5 and optionally R.sup.7 are introduced into the amphiphile
(A) by the choice of the alkyl amine according to formula
HN(R.sup.5)(R.sup.7). Preferred alkyl amines HN(R.sup.5)(R.sup.7)
for reaction with the ethylenically unsaturated carboxylic acid or
ester respectively with the first intermediate formed from the
ethylenically unsaturated acid or ester with the N,N-dialkylamine
may include, but are not limited to, any primary or secondary fatty
amine derived from one or more fatty acids having 6 to 22 carbon
atoms or its esters. Preferably the alkyl amine
HN(R.sup.5)(R.sup.7) is derived from a fatty acid or ester selected
from the group consisting of: corn oil, canola oil, coconut oil,
safflower oil, sesame oil, palm oil, cottonseed oil, soybean oil,
olive oil, sunflower oil, hemp oil, wheat germ oil, palm kernel
oil, vegetable oil, caprylic acid, capric acid, lauric acid,
stearic acid, myristic acid, myristoleic acid, palmitic acid,
palmitoleic acid, stearic acid, sapienic acid, elaidic acid,
vaccenic acid, linoleic acid, arachidic acid, arachidonic acid,
eicosapentaenoic acid, erucic acid, docosahexaenoic acid, behenic
acid, lignoceric acid, cerotic acid, oleic acids (cis- and trans-),
and any combination thereof. Suitable alkyl amines for reaction
also may include, but are not limited to, any synthetic primary or
secondary amine including, but not limited to, hexylamine,
octylamine, dodecylamine, tridecylamine, tetradecylamine,
N-methyldodecylamine, N-methyloctylamine, didodecylamine, and the
like, and any combination thereof.
[0117] In some embodiments, the reaction product of the
N,N-dialkylaminoalkylamine
H[N(R.sup.6)--R.sup.4].sub.p--N(R.sup.1)(R.sup.2), the unsaturated
carboxylic acid and the alkyl amine HN(R.sup.5)(R.sup.7) in either
sequence may form a second intermediate that may further be reacted
with (iii) one or more acids, or with one or more alkylating agents
to form the hydrate inhibitor. In such embodiments, R.sup.3 and/or
R.sup.8 of the cation moiety may depend upon, among other factors,
the alkyl group of the alkylating agent(s). In certain embodiments,
the one or more acids of formula HX may be an inorganic acid as for
example a halide acid, or a carboxylic acid, as for example formic
acid, acetic acid propionic acid, acrylic acid, methacrylic acid or
the like. In certain embodiments, the one or more alkylating agents
may be a carbonate, a halide, a sulfate, an organic sulfonate, a
hydroxide, and/or any combination thereof.
[0118] In further especially preferred embodiments, the linking
moiety L of amphiphile (A) may comprise a structure of formula (6).
Such hydrate inhibitor compounds may be characterized as a reaction
product of a N,N-dialkylaminoalkylamine of formula
HN(R.sup.6)--R.sup.4--N(R.sup.1)(R.sup.2) wherein R.sup.1, R.sup.2,
R.sup.4 and R.sup.6 have the same meanings as given above, and a
1,2-epoxyalkane of formula (18)
##STR00005##
[0119] wherein R.sup.5 has the meaning given above. Examples of
preferred 1,2-epoxyalkanes are 1,2-epoxydecane, 1,2-epoxydodecane,
1,2-epoxytetradecane, 1,2-epoxyhexadecane 1,2-epoxyoctadecane and
their mixtures. In some embodiments, the reaction product of the
N,N-dialkylaminoalkylamine and the 1,2-epoxyalkane may further be
reacted with one or more acids and/or alkylating agents whereby the
same acids and alkylating agents are preferred as in the preceding
embodiments.
[0120] In further especially preferred embodiments, the linking
moiety L of amphiphile (A) may comprise one or more of structural
elements (7a), (7b) and/or (7c). Such hydrate inhibitor compounds
may be characterized as reaction products of a dicarboxylic acid
reactant substituted with a hydrocarbyl substituent R.sup.5 with a
nitrogen containing compound having, besides a group
--N(R.sup.1)(R.sup.2), an oxygen or nitrogen atom capable of
condensing with said dicarboxylic acid reactant.
[0121] Preferred dicarboxylic acid reactants substituted with a
hydrocarbyl substituent R.sup.5 are alkylsuccinic acids,
alkenylsuccinic acids and their anhydrides. Preferably, the
nitrogen compound is a N,N-dialkylaminoalkylamine having the
structure H--[N(R.sup.6)--R.sup.4].sub.p--N(R.sup.1)(R.sup.2) or a
N,N-dialkylaminoalkanol having the structure
HO--R.sup.4--N(R.sup.1)(R.sup.2), wherein R.sup.1, R.sup.2,
R.sup.4, R.sup.6 and p have the same meanings as given above. The
reaction product between a dicarboxylic acid reactant substituted
with a hydrocarbyl substituent R.sup.5 and a
N,N-dialkylaminoalkylamine may be an amide according to formula
(7a) or (7b), or an imide according to formula (7c). The reaction
product between a dicarboxylic acid reactant substituted with a
hydrocarbyl substituent R.sup.5 and a N,N-dialkylaminoalkanol may
be an ester according to formula (8a) or (8b) and will be similarly
suited as amphiphile (A). In some embodiments, the reaction product
of the dicarboxylic acid reactant with the nitrogen containing
compound may further be reacted with one or more acids and/or
quaternizing agents suitable for converting the amino group
--N(R.sup.1)(R.sup.2) to a quaternary nitrogen compound
--N(R.sup.1)(R.sup.2)(R.sup.3).sup.+X.sup.- whereby the same acids
and alkylating agents are preferred as in the preceding
embodiments.
[0122] In a further especially preferred embodiment, the linking
moiety L of amphiphile (A) comprises a structure of formulae (9),
10(a), (10b), (11), (12a) and (12b). Such hydrate inhibitor
compounds may be characterized as unsymmetrically substituted
dicarboxylic acid diamido ammonium compounds. They may be obtained
by sequentially condensing a dicarboxylic acid with a fatty amine
HN(R.sup.5)(R.sup.7) to give an intermediate amide and/or imide,
followed by the reaction of the intermediate amide and/or imide
with a N,N-dialkylaminoalkylamine having the structure
H--[N(R.sup.6)--R.sup.4].sub.p--N(R.sup.1)(R.sup.2). The reversed
sequence of reaction steps will result in a similar product.
Preferred dicarboxylic acids have 4 to 14 and especially preferred
2 to 8 carbon atoms. The dicarboxylic acid may be further
substituted by one or more hydroxy, carboxyl or carboxymethyl
groups. Examples of preferred dicarboxylic acids are succinic acid
(leading to formula (9)), malic acid leading to formulae (10a) and
(10b)), tartaric acid leading to formula (11)) and citric acid
(leading to formulae (12a) and (12b)). The thus obtained
N,N-dialkylaminoalkylamide may be further reacted with an acid to
form an ammonium salt or it may be quaternized with an alkylating
agent whereby the same acids and alkylating agents are preferred as
in the preceding embodiments.
[0123] The amphiphile (A) may be a single amphiphile or a mixture
of two or more different amphiphiles. When (A) is a mixture of
different amphiphiles, the components may differ in their chemical
and/or physicochemical properties as for example in the alkyl chain
length and/or the branching of the lipophilic tail R.sup.5, the
chain length of the alkyl residues R.sup.1 and R.sup.2 and/or the
structure of the linking moiety L.
[0124] Nonionic Surfactant (B)
[0125] In a preferred embodiment, the nonionic surfactant (B) is an
N-acylated polyhydroxyalkylamine according to formula (19)
##STR00006##
[0126] wherein
[0127] Z is the polyhydroxyalkyl radical of a monosaccharide or
oligosaccharide;
[0128] R.sup.11 is an alkyl or alkenyl group having 8 to 18 carbon
atoms; and
[0129] R.sup.12 is an alkyl group having from 1 to 5 carbon
atoms.
[0130] The polyhydroxyalkyl radical Z is derived from
monosaccharides such as erythrose, threose, ribose, arabinose,
xylose, lyxose, allose, altrose, glucose, mannose, gulose, idose,
galactose, talose or fructose, or derivatives thereof such as
glucuronic acid or deoxyribose or oligosaccharides and
disaccharides such as saccharose, lactose, trehalose, maltose,
cellobiose or gentiobiose, and also from trisaccharides such as
raffinose. Also suitable are all commercial starch degradation
products such as glucose syrup or dextrins, eg, maltodextrins. In a
preferred embodiment, Z is a polyhydroxyalkyl radical derived from
aldohexoses and having the formula
--CH.sub.2--(CHOH).sub.4--CH.sub.2--OH. Particularly preferred is
the radical of glucose and especially of naturally occurring
D(+)-glucose. Derived from monosaccharide or oligosaccharide means
that the carbonyl group of the saccharide has been transformed into
an amino group, for example by reductive amination with an amine of
formula NH--R.sup.12.
[0131] In a preferred embodiment, R.sup.11 is an alkyl or alkenyl
group having from 8 to 16 and more preferred from 10 to 14 carbon
atoms, as for example from 8 to 14, or from 10 to 18, or from 10 to
16 carbon atoms. The alkyl or alkenyl group may be linear or
branched. Preferably it is linear. Unsaturated alkenyl groups
R.sup.11 contain one or two double bonds. Examples for preferred
alkyl and alkenyl groups are octyl, 2-ethyl hexyl, iso-nonyl,
decyl, iso-undecyl, dodecyl, iso-tridecyl, tetradecyl, pentadecyl,
hexadecyl, octadecyl, oleyl, and any mixtures thereof. In a
preferred embodiment, R.sup.11 comprises a mixture of different
alkyl and/or groups within the given chain lengths.
[0132] In a preferred embodiment, R.sup.11 together with the
carbonyl group to which it is attached, is derived from a fatty
acid. Preferred fatty acids are selected from the group consisting
of capric acid, lauric acid, stearic acid, myristic acid,
myristoleic acid, palmitic acid, palmitoleic acid, stearic acid,
sapienic acid, elaidic acid, vaccenic acid, linoleic acid, oleic
acids (cis- and trans-), and any combination thereof. In a
preferred embodiment, the fatty acid is obtained from a plant
source or an animal source selected from corn oil, canola oil,
coconut oil, safflower oil, sesame oil, palm oil, cottonseed oil,
soybean oil, olive oil, sunflower oil, hemp oil, wheat germ oil,
palm kernel oil, or tallow oil, vegetable oil, and combinations
thereof.
[0133] The radical R.sup.12 denotes hydrogen or C.sub.1-C.sub.4
alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl,
isobutyl, sec-butyl, tert-butyl, or n-pentyl. Of these, methyl is
especially preferred.
[0134] The nonionic surfactants (B) and their methods of
preparation are well known to the ones skilled in the art. For
example, the N-acylated polyhydroxyalkylamines according to formula
(19) can be manufactured by reductive amination of mono- and
oligosaccharides with an amine of formula NH--R.sup.12 and
subsequent amidation of the amine with a carboxylic acid of formula
R.sup.12--COOH or its reactive equivalent, as for example its ester
with a C.sub.1-C.sub.4 alcohol, its acid chloride, or its
anhydride.
[0135] The polyhydroxyalkyl radical of a monosaccharide or
oligosaccharide may be linear or cyclic, e.g. by forming ether,
hemiacetal and/or acetal groups.
[0136] In a preferred embodiment, the nonionic surfactant (B)
includes at least one N-acylated N-alkylglucamine according to
formula (21)
##STR00007##
[0137] wherein R.sup.11 and R.sup.12 have the meanings given
above.
[0138] In another preferred embodiment, the nonionic surfactant (B)
includes at least one cyclic N-acylated N-alkylglucamine selected
from the formulae (22), (23), and/or (24)
##STR00008##
[0139] wherein R.sup.11 and R.sup.12 have the meanings given
above.
[0140] In the gas hydrate inhibitor composition according to the
invention the portion of the nonionic surfactant (B) is between 5
and 95 wt.-%, preferably between 10 and 85 wt.-% and especially
preferred between 20 and 60 wt.-% based on the combined masses of
(A) and (B), as for example between 5 and 85 wt.-%, or between 5
and 60 wt.-%, or between 10 and 95 wt.-%, or between 10 and 60
wt.-%, or between 20 and 95 wt.-%, or between 20 and 85 wt.-% of
the combined masses of (A) and (B).
[0141] In another preferred embodiment, the portion of the
amphiphile (A) in the gas hydrate inhibitor composition according
to the invention is between 5 and 95 wt. %, preferably between 15
and 90 wt.-% and especially preferred between 40 and 80 wt.-%, as
for example between 5 and 90 wt.-%, or between 5 and 80 wt.-%, or
between 15 and 95 wt.-%, or between 15 and 80 wt.-%, or between 40
and 95 wt.-%, or between 40 and 90 wt.-% of the combined masses of
(A) and (B).
[0142] In a further preferred embodiment, the weight ratio between
amphiphile (A) and nonionic surfactant (B) is between 20:1 and
1:20, more preferably between 1:10 and 10:1 and especially
preferred between 1:3 and 3:1 as for example between 20:1 and 1:10,
or between 20:1 and 1:3, or between 10:1 and 1:20, or between 10:1
and 1:3, or between 1:3 and 1:20, or between 1:3 and 1:10.
[0143] In a preferred embodiment, the combination of components (A)
and (B) will provide a synergistic improvement of the performance
of component (A) respectively component (B) when used individually.
Accordingly, the invention in its fourth aspect provides a method
for improving the hydrate inhibitor performance of an amphiphile
(A), the method comprising the addition of a nonionic surfactant
(B) selected from N-acylated polyhydroxyalkylamines to the
amphiphile (A). According to its fifth aspect the invention
provides the use of a nonionic surfactant (B) selected from
N-acylated polyhydroxyalkylamines (B) for improving the hydrate
inhibitor performance of an amphiphile (A).
[0144] Further Surfactants (C)
[0145] Besides amphiphile (A) and nonionic surfactant (B), the
hydrate inhibitor composition may contain one or more further
surfactants (C). Often the further surfactant (C) may further
improve the hydrate inhibitor performance of the combination of
amphiphile (A) and nonionic surfactant (B). A surfactant as defined
herein is a compound that will decrease the surface tension when
added to the aqueous compositions as described herein. In a
comparison of the aqueous composition with and without surfactant
(C), the aqueous composition with surfactant needs to have a lower
surface tension. Further surfactants (C) may be selected from
anionic, nonionic, zwitterionic (amphoteric) and cationic
surfactants, wherein the further nonionic surfactant (C) is
different from the amphiphile (A) and the nonionic surfactant
(B).
[0146] Surfactants for use in the present invention typically
contain hydrophobic groups such as alkenyl, cycloalkenyl, alkyl,
cycloalkyl, aryl, alkyl/aryl or more complex aryl moieties being
from C.sub.8 to C.sub.22, preferably C.sub.10 to C.sub.20,
typically C.sub.12 to C.sub.18, and a hydrophilic moiety which may
be nonionic, anionic, cationic, or amphoteric. Further hydrophobic
groups included in the invention are polysiloxane groups and
polyoxypropylene groups.
[0147] Typically, the further cationic surfactant may be any
water-soluble compound having a positively ionized group, usually
comprising a nitrogen atom, and either one or two alkyl groups each
having an average of from C.sub.8 to C.sub.22. The anionic portion
of the further cationic surfactant may be any anion which confers
water solubility, such as formate, acetate, lactate, tartrate,
citrate, chloride, nitrate, sulfate or an alkyl sulfate ion having
up to C.sub.4 such as a higher alkyl sulfate or organic
sulfonate.
[0148] In some embodiments, the further surfactant (C) is a
cationic surfactant according to formula (20)
##STR00009##
[0149] wherein [0150] R.sup.13 is C.sub.8 to C.sub.22 alkyl or
alkenyl; [0151] R.sup.14 an alkyl group having from 1 to 4 carbon
atoms; [0152] R.sup.15 is hydrogen or an alkyl group having from 1
to 4 carbon atoms; [0153] R.sup.16 is hydrogen, an alkyl group
having from 1 to 16 carbon atoms, or an aromatic hydrocarbon having
from 6 to 16 carbon atoms, wherein 1 to 3 carbon atoms may be
replaced by nitrogen and/or oxygen; [0154] v is 0 or 1; [0155] W H
or OH; and [0156] Q.sup.- is an anion.
[0157] In some embodiments, the further cationic surfactant (C)
comprises or consists of an alkylammonium salt having one or at
most two long aliphatic chains per molecule (e.g. chains having an
average of C.sub.8 to C.sub.20 each, preferably C.sub.12 to
C.sub.18 each) and two or three short chain alkyl groups having
C.sub.1 to C.sub.4 each, e.g. methyl, ethyl, propyl and/or butyl
groups, preferably methyl groups. In further embodiments,
benzalkonium salts having one C.sub.8 to C.sub.20 alkyl group, two
C.sub.1 to C.sub.4 alkyl groups and a benzyl group are preferred as
further cationic surfactant (C). In some embodiments, alkylaryl
dialkylammonium salts in which the alkylaryl group is an alkyl
benzene group having an average of from C.sub.8 to C.sub.22,
preferably C.sub.10 to C.sub.20 and the other two alkyl groups
usually have from C.sub.1 to C.sub.4, e.g. methyl groups are
preferred as further cationic surfactant (C).
[0158] Another useful class of further cationic surfactants
comprise N-alkyl pyridinium salts wherein the alkyl group has an
average of from C.sub.8 to C.sub.22, preferably C.sub.10 to
C.sub.20 carbon atoms. Other similarly alkylated heterocyclic
salts, such as N-alkyl isoquinolinium salts, may also be used.
Other classes of further cationic surfactants which are of use in
the present invention include so called alkyl imidazoline or
quaternized imidazoline salts having at least one alkyl group in
the molecule with an average of from C.sub.8 to C.sub.22 preferably
C.sub.10 to C.sub.20. Typical examples include alkyl methyl
hydroxyethyl imidazolinium salts, alkyl benzyl hydroxyethyl
imidazolinium salts, and 2alkyl-1-alkylamidoethyl imidazoline
salts. Another class of further cationic surfactant for use
according to the current invention comprises the amido amines such
as those formed by reacting a fatty acid having C.sub.2 to C.sub.22
or an ester, glyceride or similar amide forming derivative thereof,
with a di or poly amine, such as, for example, ethylene diamine or
diethylene triamine, in such a proportion as to leave at least one
free amine group. Quaternized amido amines may similarly be
employed. Alkyl phosphonium and hydroxyalkyl phosphonium salts
having one C.sub.8 to C.sub.20 alkyl group and three C.sub.1 to
C.sub.4 alkyl or hydroxyalkyl groups may also be used as further
cationic surfactants (C) in the present invention.
[0159] In some embodiments, the further surfactant (C) is an
anionic surfactant. The further anionic surfactant may for example
comprise or consist of an at least sparingly water-soluble salt of
sulfonic or mono-esterified sulfuric acids, e.g. an alkylbenzene
sulfonate, alkyl sulfate, alkyl ether sulfate, olefin sulfonate,
alkane sulfonate, alkylphenol sulfate, alkylphenol ether sulfate,
alkylethanolamide sulfate, alkylethanolamidether sulfate, or alpha
sulfo fatty acid or its ester each having at least one alkyl or
alkenyl group with from 8 to 22, more usually from 10 to 20
aliphatic carbon atoms.
[0160] Other anionic surfactants useful as further surfactant (C)
include alkyl sulfosuccinates, such as sodium
dihexylsulfosuccinate, alkyl ether sulfosuccinates, alkyl
sulfosuccinamates, alkyl ether sulfosuccinamates, acylsarcosinates,
acyl taurides, isethionates, soaps such as stearates, palmitates,
resinates, oleates, linoleates and alkyl ether carboxylates.
Anionic phosphate esters and alkyl phosphonates, alkylamino and
imino methylene phosphonates may equally be used.
[0161] In each case the anionic surfactant typically contains at
least one alkyl or alkenyl chain having from 8 to 22, preferably
from 10 to 20 carbon atoms. The expression "ether" here-in-before
refers to compounds containing one or more glyceryl groups and/or
oxyalkylene or polyoxyalkylene groups and especially a group
containing from 1 to 150 oxyethylene and/or oxypropylene groups.
One or more oxybutylene groups may additionally or alternatively be
present. For example, the sulfonated or sulfated surfactant may be
sodium dodecyl benzene sulfonate, potassium hexadecyl benzene
sulfonate, sodium dodecyl, dimethyl benzene sulfonate, sodium
lauryl sulfate, sodium tallow sulfate, potassium oleyl sulfate,
ammonium lauryl sulfate, sodium tallow sulfate, potassium oleyl
sulfate, ammonium lauryl monoethoxy sulfate, or monethanolamine
cetyl 10 mole ethoxylate sulfate.
[0162] Preferred anionic surfactants are sodium salts. Other salts
of commercial interest include those of potassium, lithium,
calcium, magnesium, ammonium, monoethanolamine, diethanolamine,
triethanolamine, alkyl amines containing up to seven aliphatic
carbon atoms, and alkyl and/or hydroxyl alkyl phosphonium.
[0163] In some embodiments, the further surfactant (C) is a
non-ionic surfactant. The further non-ionic surfactant may be e.g.
polyethoxylated alcohols, polyethoxylated mercaptans, glucamines
and their alkoxylates, glucamides and their alkoxylates,
alkylpolyglucacides, polyethoxylated carboxylic acids,
polyethoxylated amines, polyethoxylated alkylolamides,
polyethoxylated alkylphenols, polyethoxylated glyceryl esters,
polyethoxylated sorbitan esters, polyethoxylated phosphate esters,
polyethoxylated tertiary acetylenic glycols, and the propoxylate or
ethoxylated and propoxylated analogues of all the aforesaid
ethoxylated non-ionics, all having a C.sub.8 to C.sub.22 alkyl or
alkenyl group and up to 20 ethyleneoxy and/or propyleneoxy groups.
Also suited are partial esters of polyhydric compounds having three
or more as for example three to six hydroxyl groups with fatty
acids. In some embodiments the polyol may be glycerol,
trimethylolpropane, erythritol, pentaerythrit, sorbitan, sorbitol,
xylitol and their mixtures. Further included are
polyoxypropylene/polyethylene oxide block copolymers,
polyoxybutylene/polyoxyethylene copolymers and
polyoxybuylene/polyoxypropylene copolymers. The polyethoxy,
polyoxypropylene and polyoxybutylene compounds may be end capped
with, e.g. methyl or benzyl groups to reduce the foaming tendency.
Other non-ionic surfactants (C) which may optionally be present
include C.sub.8 to C.sub.22 alkanolamides of a mono or di-lower
alkanolamine, such as coconut monoethanolamide.
[0164] In some embodiments, the further surfactant (C) is an
amphoteric surfactant. The amphoteric surfactant may for example be
a betaine, e.g. a betaine of the formula
(R.sup.17).sub.3N.sup.+CH.sub.2COO.sup.-, wherein each R.sup.17 may
be the same or different and is an alkyl, cycloalkyl, alkenyl or
alkaryl group and preferably at least one, and more preferably not
more than one R.sup.17 has an average of from C.sub.8 to C.sub.20,
e.g. C.sub.10 to C.sub.18 of an aliphatic nature and each other
R.sup.17 has an average of from C.sub.1 to C.sub.4.
[0165] Other amphoteric surfactants suited for use as further
surfactant (C) include quaternary imidazolines, alkyl amine ether
sulfates, sulfobetaines and other quaternary amine or quaternised
imidazoline sulfonic acids and their salts, and zwitterionic
surfactants, e.g. N-alkyl taurines, carboxylates amidoamines such
as
R.sup.18CONH(CH.sub.2).sub.2N.sup.+(CH.sub.2CH.sub.2CH.sub.3).sub.2--CH.s-
ub.2CO.sup.-.sub.2 and amido acids having, in each case,
hydrocarbon groups capable of conferring surfactant properties
(R.sup.18 is either alkyl, cycloalkyl, alkenyl or alkaryl groups
having from C.sub.8 to C.sub.20 of an aliphatic nature). Typical
examples include 2-tallow alkyl, 1-tallow amido alkyl,
1-carboxymethyl imidazoline and 2-coconut alkyl N-carboxymethyl 2
(hydroxyalkyl) imidazoline. Generally speaking, any water soluble
amphoteric or zwitterionic surfactant compound which comprises a
hydrophobic portion including C.sub.8 to C.sub.20 alkyl or alkenyl
group and a hydrophilic portion containing an amine or quaternary
ammonium group and a carboxylate, sulfate or sulfonic acid group
may be used in the present invention.
[0166] Similarly, suited amphoteric surfactants (C) are amine
oxides e.g. amine oxides containing one or two (preferably one)
C.sub.8 to C.sub.22 alkyl groups, the remaining substituent or
substituents being preferably lower alkyl groups, e.g. C.sub.1 to
C.sub.4 alkyl groups or benzyl groups. Particularly preferred for
use as further surfactant (C) according to the current invention
are surfactants which are effective as wetting agents; typically,
such surfactants are effective at lowering the surface tension
between water and a hydrophobic solid surface. Surfactants are
preferred which do not stabilize foams to a substantial extent.
[0167] Polyfluorinated anionic, nonionic or cationic surfactants
may also be present as further surfactant (C). Examples of such
surfactants are polyfluorinated alkyl sulfates and polyfluorinated
quaternary ammonium compounds.
[0168] Mixtures of two or more of the foregoing further surfactants
(C) may be used. They may be of the same or different ionicity. In
some embodiments, mixtures of nonionic surfactants with cationic
and/or amphoteric surfactants may be used. Typically, mixtures of
anionic and cationic surfactants are avoided, which are often less
mutually compatible.
[0169] In a preferred embodiment, the share of the further
surfactant (C) in the gas hydrate inhibitor composition according
to the invention is between 1 and 30 wt.-%, preferably between 3
and 20 wt.-% and especially preferred between 5 and 10 wt.-% based
on the combined masses of (A) and (B), as for example between 1 and
20 wt.-%, or between 1 and 10 wt.-%, or between 3 and 30 wt.-%, or
between 3 and 10 wt.-%, or between 5 and 30 wt.-%, or between 5 and
20 wt.-% of the combined masses of (A) and (B). This means that the
further surfactant (C) is added on top into a composition
comprising (A) and (B) in an amount that is up to 30% of the
combined masses of (A) and (B). In an especially preferred
embodiment, the gas hydrate inhibitor composition according to the
invention does not contain a further surfactant.
[0170] The presence of the further surfactant (C) will provide a
further improvement of the performance of components (A) and (B).
For example, it will allow for further reduction of treat rates
even beyond the two-component system comprising A and B only.
Additionally, it may further improve upon secondary properties,
which can further reduce the need for additional treatments to
address undesirable secondary properties (i.e. emulsion breaker to
address emulsion formation).
[0171] Application
[0172] In its second aspect, this invention relates to a method for
inhibiting the agglomeration of hydrates and often also the
formation of hydrates, wherein the composition according to the
first aspect of the invention is brought into contact with a system
comprising water and a gas and being susceptible to hydrate
formation. The method may be applied to prevent or reduce or
mitigate plugging of conduits, pipes, transfer lines, pipelines,
valves, and other places or equipment where hydrocarbon hydrate
solids may form under the conditions.
[0173] In its third aspect, this invention relates to the use of a
composition according to the first aspect of the invention for
inhibiting the agglomeration of hydrates and often also the
formation of hydrates. The composition according to the first
aspect of the invention may be used to prevent or reduce or
mitigate plugging of conduits, pipes, transfer lines, pipelines,
valves, and other places or equipment where hydrocarbon hydrate
solids may form under the conditions.
[0174] The term "inhibiting" or "inhibited" is used herein in a
broad and general sense to mean any improvement in preventing,
reducing, retarding, mitigating, controlling and/or delaying the
formation, growth and/or agglomeration of hydrates, especially of
hydrocarbon hydrates and particularly of light hydrocarbon gas
hydrates in any manner, including, but not limited to kinetically,
thermodynamically, by dissolution, by breaking up, by dispersion,
other mechanisms, or any combinations thereof.
[0175] The term "formation" or "forming" relating to hydrates is
used herein in a broad and general manner to include, but not being
limited to, any formation of hydrate solids from water and gases
and especially from water and hydrocarbon(s) or hydrocarbon
gas(es), growth of such hydrate solids, agglomeration of such
hydrates, accumulation of hydrocarbon hydrates on surfaces, any
deterioration of hydrate solids plugging or other problems in a
system and combinations thereof.
[0176] The method according to the second aspect of the invention
and the use of the hydrate inhibitor composition according to the
third aspect of the invention are equally useful for inhibiting
hydrate formation for many gases. They are especially useful for
inhibiting hydrate formation of hydrocarbons, hydrocarbon gases and
their mixtures. They are particularly useful for treatment of
lighter and/or low-boiling, C.sub.1 to C.sub.5 hydrocarbon gases or
gas mixtures at elevated pressure and/or low temperature
conditions. Non-limiting examples of such "low-boiling" gases
include methane, ethane, propane, n-butane, isobutane, isopentane
and mixtures thereof as for example those encountered in natural
gas including various natural gas mixtures that are present in many
gas and/or oil formations and natural gas liquids (NGL). The
hydrates of all these low-boiling hydrocarbons are also referred to
as gas hydrates. In embodiments, the compositions and methods
according to this invention are useful for inhibiting gas hydrate
formation in a variety of black oils, heavy black oils to
condensates, from API 10-60. The hydrocarbons and hydrocarbon gases
may also comprise other compounds including, but not limited to
hydrogen, carbon dioxide, hydrogen sulfide, and other compounds
commonly found in gas/oil formations or processing plants, either
naturally occurring or used in recovering/processing hydrocarbons
from the formation or both, and mixtures thereof.
[0177] In embodiments, the gas hydrate inhibitor composition is
applied to fluids that contain various levels of oil, brine or both
having various levels of salinity. In one embodiment, the fluid has
a salinity of about 0.1 to about 25 wt.-% or about 10 to about 25
wt.-%.
[0178] In some embodiments, the hydrate inhibitor composition is
applied to a fluid that contains various levels of water cut. One
of ordinary skill in the art understands that "water cut" refers to
the volume percent of water in a composition containing an oil and
water. In a preferred embodiment, the water cut is from about 1 to
about 80 vol.-%. In more preferred embodiments, the water cut is
from about 1 to about 60 vol.-%, from about 5 to about 40 vol.-%,
from about 10 to about 30 vol.-% as for example from about 1 to 40
vol.-%, or from about 1 to 30 vol.-%, or from about 5 to 80 vol.-%,
or from about 5 to 60 vol.-%, or from about 5 to 30 vol.-%, or from
about 10 to 80 vol.-%, or from about 10 to 60 vol.-%, or from about
10 to 40 vol.-%, or from about 15 to about 80 vol.-% with respect
to the total volume of water and hydrocarbon phases. The
combination of the amphiphile (A) with the nonionic surfactant (B)
according to the invention allows to increase the maximum treatable
water cut over the use of the individual components.
[0179] The method according to the second aspect and the use
according to the third aspect of the present invention involve
contacting a mixture of a gas and water and especially a mixture of
hydrocarbon gas and water susceptible to hydrate formation with a
composition according to the first aspect of the invention. When an
effective amount of the composition is used, hydrate blockage is
inhibited. In the absence of such effective amount, hydrate
blockage is not inhibited.
[0180] The compounds of the present invention are added into the
mixture of hydrocarbons and water at any concentration effective to
inhibit the formation of hydrates under the given conditions.
Preferably, the concentration of the active gas hydrate inhibitor
composition added into the mixture of hydrocarbons and water is
between 0.001 wt.-% and about 4.0 wt.-% relative to the total
weight of the aqueous phase being part of the mixture of fluids,
water and hydrocarbon, to be inhibited from hydrate formation. More
preferably, the gas hydrate inhibitor composition concentration is
between about 0.005 wt.-% and about 1.5 wt.-% and especially
preferred between about 0.01 wt.-% and about 0.50 wt.-%, as for
example between about 0.001 wt.-% and about 1.5 wt.-%, or between
about 0.001 wt.-% and about 0.5 wt.-%, or between about 0.005 wt.-%
and about 4.0 wt.-%, or between about 0.005 wt.-% and about 0.5
wt.-%, or between about 0.01 wt.-% and about 4.0 wt.-%, or between
0.01 wt.-% and about 1.5 wt.-%.
[0181] Accordingly, a mixture of oil and water being in presence of
gases and especially a mixture of hydrocarbons and water being in
presence of hydrocarbon gases treated with a hydrate inhibitor
composition according to the first aspect of the invention
preferably comprises between about 0.001 wt.-% and about 4.0 wt.-%
more preferably between about 0.005 wt.-% and about 1.5 wt.-%, and
especially preferred between 0.01 wt.-% and about 0.50 wt.-% as for
example between about 0.001 wt.-% and about 1.5 wt.-%, or between
about 0.001 wt.-% and about 0.50 wt.-%, or between about 0.005
wt.-% and about 4.0 wt.-%, or between about 0.005 wt.-% and about
0.50 wt.-%, or between about 0.01 wt.-% and about 4.0 wt.-% or
between about 0.01 wt.-% and about 1.5 wt.-% relative to the total
weight of the aqueous phase of a composition according to the first
aspect of the invention.
[0182] The contacting may be achieved by a number of ways,
including mixing, blending with mechanical mixing equipment or
devices, stationary mixing setup or equipment, magnetic mixing or
other suitable methods, other equipment and means known to one
skilled in the art and combinations thereof to provide adequate
contact and/or dispersion of the composition in the mixture. The
contacting can be made in-line or batchwise or both. The various
components of the composition may be mixed prior to or during
contact, or both. If needed or desired, the composition or some of
its components may be optionally removed or separated mechanically,
chemically, or by other methods known to one skilled in the art, or
by a combination of these methods after the hydrate formation
conditions are no longer present.
[0183] Preferably, contacting of the hydrate inhibitor composition
according to the invention with the mixture of gas and water is
conducted prior to substantial formation of hydrates. More
preferably it is conducted prior to the onset of hydrate formation.
This may be at high temperatures as for example temperatures
prevailing downhole, at low pressures and/or at low water-cuts.
[0184] The hydrate inhibitor composition may be introduced into the
fluid comprising gas and water through a conduit or an injection
point. In certain embodiments, the hydrate inhibitor composition
may be introduced into a wellbore, a conduit, a vessel, and the
like and may contact and/or be introduced into a fluid residing
therein. An exemplary application point for the petroleum liquid
production operations is to introduce hydrate inhibitor into the
subsea wellhead itself, upstream of the well choke valve. This
ensures that during a shut-in the composition can disperse
throughout the area where natural gas hydrates have the highest
risk of occurring. Application of the hydrate inhibitor composition
can also occur at other areas in the wellhead or flowline manifold
or the flowline itself, considering the density of the injected
liquid. If the injection point is well above the gas hydrate
formation depth, then the hydrate inhibitor composition may be
formulated with a solvent having a density high enough that the
composition will sink in the flowline to collect at the water/oil
interface. In embodiments, application is also used in pipelines or
anywhere in the system where the potential for agglomerates of gas
hydrate formation exists.
[0185] The method according to the second aspect and the use
according to the third aspect of the invention are equally
applicable for fluids which are flowing as well as for fluids which
are substantially stationary. Accordingly, the fluid may be within
a vessel, or within a conduit (e.g., a conduit that may transport
the fluid), or within a subterranean formation and/or a wellbore
penetrating a portion of the subterranean formation. Examples of
conduits include, but are not limited to, pipelines, production
piping, subsea tubulars, process equipment, and the like as used in
industrial settings and/or as used in the production of oil and/or
gas from a subterranean formation, and the like. The conduit may in
certain embodiments penetrate at least a portion of a subterranean
formation, as in the case of an oil and/or gas well. In particular
embodiments, the conduit may be a wellbore or may be located within
a wellbore penetrating at least a portion of a subterranean
formation. Such oil and/or gas well may, for example, be a subsea
well (e.g., with the subterranean formation being located below the
sea floor), or it may be a surface well (e.g., with the
subterranean formation being located belowground). A vessel or
conduit according to other embodiments may be located in an
industrial setting such as a refinery (e.g., separation vessels,
dehydration units, pipelines, heat exchangers, and the like), or it
may be a transportation pipeline.
[0186] The method according to the second aspect and the use
according to the third aspect of the present invention are
particularly suitable for lower boiling hydrocarbons or hydrocarbon
gases at ambient temperature when the pressure is at or greater
than atmospheric pressure. (i.e. about 101 kPa), preferably greater
than about 1 MPa, and more preferably greater than about 5 MPa. The
pressure in certain formation or processing plants or units could
be much higher, say greater than about 20 MPa. There is no specific
high-pressure limit. The present method can be used at any pressure
that allows formation of hydrocarbon gas hydrates. Lower
temperatures tend to favor hydrate formation, thus requiring the
treatment with the composition of the present invention; at much
higher temperatures, however, hydrocarbon hydrates are less likely
to form, thus obviating the need of carrying out any
treatments.
[0187] For ease of handling, the hydrate inhibitor composition
comprising as active ingredients an amphiphile (A), a nonionic
surfactant (B) and optionally a further surfactant (C), may be
formulated with a diluent. Preferred diluents are generally
solvents for the virgin form of the active ingredients. Such
solvents include, but are not limited to monohydric alcohols having
1 to 12 carbon atoms like methanol, ethanol, n-propanol,
iso-propanol, n-butanol, iso-butanol, tert-butanol, pentanol,
hexanol, heptanol, octan-1-ol, octan-2-ol and 2-ethylhexan-1-ol;
glycols like ethylene glycol, 1,2-propylene glycols, 1,3-propylene
glycol, hexylene glycol and glycerol; ether solvents like ethylene
glycol mono butylether (butyl cellosolve), ethylene glycol dibutyl
ether, and tetrahydrofuran; ketonic solvents like acetone,
methylethylketone, diisobutylketone, N-methylpyrrolidone,
cyclohexanone; acetonitrile; esters such as ethyl acetate, propyl
acetate and butyl acetate; and mixtures thereof. In a further
preferred embodiment, a higher boiling aliphatic, aromatic or
alkylaromatic hydrocarbon, or a mixture thereof has proven to be
advantageous. Most preferred solvents are methanol, ethanol,
glycerol, decane, toluene, xylene, diethylbenzene, naphthalene,
tetralin, decalin, and commercial solvent mixtures such as
Shellsol.RTM., Exxsol.RTM., Isopar.RTM., Solvesso.RTM. types,
diesel, Solvent Naphtha and/or kerosene. The more polar organic
solvents like for example monohydric and polyhydric alcohols having
1 to 5 and especially having 1 to 3 carbon atoms may also be used
in admixture with water, brine, and/or seawater. The selection of a
suitable diluent or combination of diluents is important to
maintain a stable solution of the compounds during storage and to
provide stability and reduced viscosity for the inhibitor solutions
when they are injected against a pressure of 200 to 30,000 psi. If
a diluent is present in the formulation of the hydrate inhibitor
composition, its concentration is preferably in the range of from
about 1 to about 95 wt.-%, more preferably from about 10 to about
90 wt.-%, and especially preferred from about 20 to about 80%, as
for example from about 1 to about 90 wt.-%, or from about 1 to
about 80 wt.-%, or from about 10 to about 95 wt.-%, or from about
10 to about 80 wt.-%, or from about 20 to about 95 wt.-%, or from
about 20 to about 90 wt.-%, based on the weight of the formulation
comprising (A), (B), optionally (C) and the diluent. Such
formulations can be delivered in subsea umbilicals.
[0188] In a preferred embodiment, finished product formulations are
made to approximately 40 to 75 wt.-% as for example 60 wt.-% active
content and 25 to 60 wt.-% as for example 40 wt.-% of a solvent.
They are made as active as possible to save on space, logistics,
and pump capacity which are all relevant concerns where treating
production fluids offshore. However, often the maximum viscosity
specified for a concrete application (commonly <100 cP at
4.degree. C.) sets an upper limit.
[0189] The present invention may also be used in combination with
other means of hydrate inhibition such as the use of thermodynamic
or kinetic inhibitors discussed in the background section. These
other hydrate inhibitors may be of the same or different type of
hydrate inhibitor used in the composition. If mixtures of hydrate
inhibitors are used, the mixture may be added to the hydrocarbon
and water containing process stream through a single port or
multiple ports. Alternatively, individual hydrate inhibitors may be
added at separate ports to the process stream.
[0190] The present invention may also be used in combination with
other oil field flow assurance and integrity compounds such as, but
not limited to, corrosion inhibitors, scale inhibitors, paraffin
inhibitors, asphaltene inhibitors, drilling fluids, fracturing
fluids, completion fluids, antifoams, emulsion breakers, and/or
water clarifiers.
EXAMPLES
[0191] Test Procedure 1: Evaluation of Hydrate Inhibitor
Formulations.
[0192] To a 100 mL stainless steel reactor, attached to thermostat
and a liquid handling system, dodecane (10 mL), brine (20 mL of 5%
NaCl, density of 1.07 g/cm.sup.3 at 25.degree. C.), and the
anti-agglomerant formulation were added at 30.degree. C. The
reactor was pressurized to 95 bar with Erdgas H (see Table 1 for
composition). The stirrer speed was adjusted to 1000 rpm for 1 min
to saturate the liquid with gas. Subsequently the stirrer speed was
reduced to 200 rpm, and a temperature setting of -10.degree. C. was
initiated. Monitoring the internal temperature of the reactor
showed a characteristic exotherm indicative of hydrate formation
below a threshold temperature. If the exotherm was accompanied by a
prolonged increase in stirrer power uptake this was indicative of
agglomeration, signifying a failure. If the stirrer power remained
constant or following an increase returned to the original
baseline, agglomeration was prevented; indicating a pass.
[0193] For evaluation of their hydrate inhibitor performance, the
testing was started with 0.3 wt.-% of the hydrate inhibitor,
formulated as a 60% active solution in methanol. If samples failed
at this dose rate, they were labelled as >0.3 wt.-% minimum
effective dose (MED) and were not tested further. If samples
initially tested at 0.3 wt.-% passed, they were sequentially and
incrementally reduced in dose rate by 0.05 wt.-% each time until a
dose rate was used that failed. When that occurred, the last
passing dose rate was input into the Table (4) as the Minimum
Effective Dose (MED).
TABLE-US-00001 TABLE 1 Erdgas H gas composition Component Name
Chemical Symbol Amount (mol-%) Nitrogen N.sub.2 0.14 Carbon Dioxide
CO.sub.2 0.00 Methane C.sub.1 87.56 Ethane C.sub.2 7.60 Propane
C.sub.3 3.00 i-Butane i-C.sub.4 0.50 n-Butane n-C.sub.4 0.80
i-Pentane i-C.sub.5 0.20 n-Pentane n-C.sub.5 0.20
[0194] Test Procedure 2: Water Drop Testing
[0195] Into a graduated 100 mL cylinder with conical bottom
(typically used for emulsion testing), 50 mL of oil and 50 mL of
water were charged. The water was 6% brine (using NaCl) and the oil
was a medium crude from the Gulf of Mexico. To the 100 mL of total
fluids 1 wt.-% in respect to the aqueous phase of a hydrate
inhibitor (as a 60 wt.-% active formulation) were added. A dose
rate of 1% was deliberately chosen to highlight the effect of the
hydrate inhibitors on the water drop. The bottles were capped,
shaken vigorously by hand, and allowed to stand at room temperature
for 1 minute, at which point the amount of water that could be
observed as a separate phase was recorded. This number was then
multiplied by 2 to obtain the results shown in Table 4 as a percent
of water present. A value of 100% means that all the water was
observed as a separate phase. If less than 100% was observed, the
remaining water was either within the oil or as part of a "rag
layer" or emulsion layer.
[0196] For testing, gas hydrate inhibitor formulations were
prepared by blending amphiphiles (A) according to table 2 and
nonionic surfactants (B) according to table 3 with the weight
ratios according to table 4. For ease of handling, the formulations
were adjusted to 60 wt.-% active content with methanol.
[0197] These formulations were tested for their minimum dosage rate
for hydrate inhibition according to test procedure 1. The minimum
dosage rates for a pass given in table 4 refer to the required
minimum dosage of active ingredient.
TABLE-US-00002 TABLE 2 Characterization of tested amphiphiles A)
Res- idue A1 A2 A3 A4 L
--N(R.sup.7)--C(.dbd.O)--(CH.sub.2).sub.2--N(R.sup.6)--(CH.sub.2).sub.t--
- --C(.dbd.O)--N(R.sup.6)--(CH.sub.2).sub.t--
--CH(OH)--CH.sub.2--N(R.sup.6)--(CH.sub.2).sub.t-- ##STR00010##
R.sup.1 n-butyl n-butyl n-butyl methyl R.sup.2 n-butyl n-butyl
n-butyl methyl R.sup.3 C.sub.2H.sub.5 H H
--CH.sub.2--CH(OH)--CH.sub.3 R.sup.5 C.sub.12H.sub.25 coconut cut
C.sub.10H.sub.21 C.sub.12H.sub.25 R.sup.6 H H H -- R.sup.7 H -- --
-- t 3 3 3 3 X.sup.- ethyl sulfate acrylate methyl sulfate acetate
Coconut cut comprises as main components 51 wt.-% C.sub.12H.sub.25,
and 16 wt.-% C.sub.14H.sub.29.
TABLE-US-00003 TABLE 3 Characterization of tested nonionic
surfactants B) B1 N-C.sub.18-acyl-N-methyl-glucamide B2
C.sub.8/C.sub.10 Cyclic glucamide B3 (comp.) Sorbitan monolaurate
B4 (comp.) Sorbitol C.sub.8-C.sub.18 fatty acid ester Coco alkyl
comprises as main components 51 wt.-% C.sub.12H.sub.25, and 16
wt.-% C.sub.14H.sub.29.
TABLE-US-00004 TABLE 4 Gas hydrate inhibitor (wt.-% active) MED
water drop Example Amphiphile A Surfactant B (wt.-%) (%) a: Results
from autoclave testing (components testing; comparative) 1 (comp.)
A1 (100) -- 0.30 80 2 (comp.) A2 (100) -- 0.30 84 3 (comp.) A3
(100) -- 0.30 76 4 (comp.) A4 (100) -- 0.30 74 5 (comp.) -- B1
(100) >0.30.sup.(a) 64 6 (comp.) -- B2 (100) >0.30.sup.(a) 66
7 (comp.) -- B3 (100) 0.30 60 8 (comp.) -- B4 (100)
>0.30.sup.(a) 62 b: Results from autoclave testing (formulations
containing A1) 9 A1 (50.0) B1 (50.0) 0.10 86 10 A1 (71.4) B1 (28.6)
0.10 86 11 A1 (28.6) B1 (71.4) 0.15 86 12 A1 (50.0) B2 (50.0) 0.10
88 13 A1 (71.4) B2 (28.6) 0.10 86 14 (comp.) A1 (50.0) B3 (50.0)
0.25 82 15 (comp.) A1 (71.4) B3 (28.6) 0.30 82 16 (comp.) A1 (50.0)
B4 (50.0) 0.25 80 17 (comp.) A1 (71.4) B4 (28.6) 0.20 80 c: Results
from autoclave testing (formulations containing A2) 18 A2 (50.0) B1
(50.0) 0.10 94 19 A2 (71.4) B1 (28.6) 0.10 96 20 A2 (50.0) B2
(50.0) 0.10 96 21 A2 (71.4) B2 (28.6) 0.05 94 22 A2 (28.6) B2
(71.4) 0.15 94 23 (comp.) A2 (50.0) B3 (50.0) 0.30 90 24 (comp.) A2
(71.4) B3 (28.6) 0.25 88 25 (comp) A2 (50.0) B4 (50.0) 0.25 88 26
(comp.) A2 (71.4) B4 (28.6) 0.20 88 d: Results from autoclave
testing (formulations containing A3) 27 A3 (50.0) B1 (50.0) 0.20 84
28 A3 (71.4) B1 (28.6) 0.20 84 29 A3 (50.0) B2 (50.0) 0.20 84 30 A3
(71.4) B2 (28.6) 0.20 86 31 (comp.) A3 (50.0) B3 (50.0) 0.30 82 32
(comp.) A3 (71.4) B3 (28.6) 0.25 80 33 (comp.) A3 (50.0) B4 (50.0)
0.30 78 34 (comp.) A3 (71.4) B4 (28.6) 0.30 78 e: Results from
autoclave testing (formulations containing A4) 35 A4 (50.0) B1
(50.0) 0.20 82 36 A4 (71.4) B1 (28.6) 0.15 84 37 A4 (50.0) B2
(50.0) 0.15 82 38 A4 (71.4) B2 (28.6) 0.15 84 39 (comp.) A4 (50.0)
B3 (50.0) 0.30 78 40(comp.) A4 (71.4) B3 (28.6) 0.25 80 41 (comp.)
A4 (50.0) B4 (50.0) 0.30 78 42 (comp.) A4 (71.4) B4 (28.6) 0.25 78
.sup.(a)>0.30 wt.-% means it did not pass at 0.30 wt.-% dose
rate and was not tested at higher concentration.
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