U.S. patent application number 14/282267 was filed with the patent office on 2014-09-11 for additive for preserving the fluidity of fluids containing gas hydrates.
This patent application is currently assigned to AKZO NOBEL N.V.. The applicant listed for this patent is AKZO NOBEL N.V.. Invention is credited to Martin HELLSTEN, Hans OSKARSSON.
Application Number | 20140256998 14/282267 |
Document ID | / |
Family ID | 38171089 |
Filed Date | 2014-09-11 |
United States Patent
Application |
20140256998 |
Kind Code |
A1 |
HELLSTEN; Martin ; et
al. |
September 11, 2014 |
ADDITIVE FOR PRESERVING THE FLUIDITY OF FLUIDS CONTAINING GAS
HYDRATES
Abstract
Anti-agglomerants for gas hydrates, comprising alkoxylated
and/or acylated non-quaternary nitrogen-containing compounds,
method for inhibiting the agglomeration of gas hydrates in a
conduit, and compositions comprising the gas hydrate
anti-agglomerant, a corrosion inhibitor and/or a paraffin
deposition inhibitor.
Inventors: |
HELLSTEN; Martin; (Oedsmal,
SE) ; OSKARSSON; Hans; (Stenungsund, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AKZO NOBEL N.V. |
ARNHEM |
|
NL |
|
|
Assignee: |
AKZO NOBEL N.V.
ARNHEM
NL
|
Family ID: |
38171089 |
Appl. No.: |
14/282267 |
Filed: |
May 20, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12293922 |
Oct 14, 2008 |
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PCT/EP2007/052485 |
Mar 16, 2007 |
|
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14282267 |
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60838992 |
Aug 21, 2006 |
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Current U.S.
Class: |
585/15 ; 252/384;
560/251; 564/504 |
Current CPC
Class: |
C07C 7/20 20130101; Y10T
137/0391 20150401; C09K 8/524 20130101; C09K 8/52 20130101; C09K
2208/22 20130101 |
Class at
Publication: |
585/15 ; 252/384;
564/504; 560/251 |
International
Class: |
C07C 7/20 20060101
C07C007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2006 |
EP |
06111496.3 |
Claims
1. An anti-agglomerant for gas hydrates, which comprises at least
one surface-active non-quaternary nitrogen-containing compound
chosen from the group of compounds having the formulae IA and II:
##STR00016## wherein R is a C.sub.6-C.sub.24 hydrocarbyl group; m
is 2 or 3; a=0-4; b is at least 1 at each position; .SIGMA.b on
average is 2-12; c is 0 or 1; d on average is 0-5; each A is
independently selected from H, --C(.dbd.O)CH.sub.3,
--C(.dbd.O)CH.sub.2CH.sub.3, C1-C3 alkyl groups,
--[CH.sub.2CH(X)O], H, and --[CH.sub.2CH(X)O], --C(.dbd.O)CH.sub.3,
wherein X is --CH.sub.3 or --CH.sub.2CH.sub.3, e is 1-3, and the
sum of all e in the molecule is at most 6 on average; provided that
at least one of groups A is selected from the group consisting of
--[CH.sub.2CH(X)O], H, --[CH.sub.2CH(X)O], --C(.dbd.O)CH.sub.3,
--C(.dbd.O)CH.sub.3, and --C(.dbd.O)CH.sub.2CH.sub.3; ##STR00017##
wherein R'C(.dbd.O)-- is an acyl group with 6-24 carbon atoms;
o=0-3, p=0-3, .SIGMA.(o+p) on average is 0-6; m is 2 or 3, and each
A is independently selected from H, --[CH.sub.2CH(X)O], H,
--[CH.sub.2CH(X)O], --C(.dbd.O)CH.sub.3, --C(.dbd.O)CH.sub.3,
--C(.dbd.O)CH.sub.2CH.sub.3 and C1-C3 alkyl groups; provided that
at least one of groups A is --[CH.sub.2CH(X)O], H,
--[CH.sub.2CH(X)O], --C(.dbd.O)CH.sub.3, --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.2CH.sub.3, wherein X, e and .SIGMA.e have the
same meaning as for IA; or their salts; or any combination
thereof.
2. Anti-agglomerant according to claim 1 selected from the group of
compounds having the formulae IIA and IIB, wherein IIA has the
formula ##STR00018## wherein n is at least 1 at each position and
.SIGMA.n on average is 2-4, m is 2 or 3, R(C.dbd.O)-- and A are as
defined for II except that X is --CH.sub.3, provided that at least
one of A is --[CH.sub.2CH(CH.sub.3)O], H,
--[CH.sub.2CH(CH.sub.3)O], --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.3, wherein e and .SIGMA.e are as defined for II;
IIB has the formula ##STR00019## wherein m is 2 or 3; R(C.dbd.O)--
and A are as defined for II except that X is --CH.sub.3, provided
that at least one of A is --[CH.sub.2CH(CH.sub.3)O], H,
--[CH.sub.2CH(CH.sub.3)O], --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.3, wherein e and .SIGMA.e are as defined for II;
their salts; or any combination thereof.
3. Anti-agglomerant according to claim 1, comprising the compound
of formula IA, wherein R is a C.sub.8-C.sub.18 hydrocarbyl group; a
is 0 or 1; m is 3; c is 0; the sum of b on average is 2-6; and all
A are either --[CH.sub.2CH(CH.sub.3)O], H, wherein the sum of all e
in the molecule is 2 or 3, or --C(.dbd.O)CH.sub.3.
4. Anti-agglomerant according to claim 3 wherein .SIGMA.b on
average is 2-3.
5. A method for inhibiting the agglomeration of gas hydrates in a
conduit, where the conduit contains a flowing mixture comprising
hydrocarbons with 1-4 carbon atoms and water and where hydrates are
formed from the hydrocarbons and water, the method comprising the
steps: a) adding to the mixture an anti-agglomerant as defined in
any of the previous claims in an amount that is effective to
inhibit the agglomeration of hydrates at the prevailing temperature
and pressure in the conduits b) flowing the mixture containing the
anti-agglomerant through the conduit.
6. The method according to claim 5 wherein the anti-agglomerant is
added to the hydrocarbon/water mixture in an amount of 0.05-10%,
based on the water content of the hydrocarbon/water mixture.
7. The method according to claim 5 wherein a corrosion inhibitor
and/or a paraffin deposition inhibitor are added to the
hydrocarbon/water mixture.
8. A composition containing a) 1 part by weight of the gas hydrate
anti-agglomerant as defined in claim 1 and b) 0.0001-0.1 parts by
weight of a corrosion inhibitor and/or a paraffin deposition
inhibitor.
Description
[0001] This is a Division of application Ser. No. 12/293,922, filed
Oct. 14, 2008, now pending, which is a 371 of PCT/EP2007/052485
filed Mar. 16, 2007, claiming priority of Provisional Application
60/838,992 filed Aug. 21, 2006, and European Patent Application
06111496.3 filed Mar. 21, 2006, the disclosures of which are all
incorporated herein by reference.
[0002] The present invention relates to the use of a group of
alkoxylated and/or acylated non-quaternary nitrogen-containing
compounds as anti-agglomerants for gas hydrates.
[0003] When low molecular hydrocarbon gases such as methane,
ethane, propane, butane, and iso-butane are subjected to high
pressure in the presence of water, a particular type of ice,
so-called gas hydrate, may be formed. The maximum temperature for
this formation will depend on the gas pressure. At a sufficiently
high pressure the gas hydrate can be stable up to +25.degree.
C.
[0004] The formation of gas hydrates has important practical
implications in oil and gas production, particularly for the
transport of natural gas in offshore pipelines where both high
pressure and low temperature prevail. If no measures are taken, the
pipeline is easily blocked by the formation of gas hydrates.
[0005] It has long been common practice to add either methanol or
ethylene glycol to the gas/water or gas/water/oil stream in order
to decrease the freezing point of the gas/water mixture. This
method, which is called thermodynamic inhibition, will prevent
primary formation of gas hydrates. However, it necessitates an
addition of 10-60% of the amount of water present in the fluid,
depending on the temperature and the gas pressure. This high level
of addition will also make it necessary to recover the additive at
the destination point. Altogether, this makes thermodynamic
inhibition a rather expensive operation.
[0006] This in turn has led to the search for additives that can be
used in much lower dosages, and this search has resulted in two
principally different modes of action, kinetic inhibition and
dispersion. In both cases the normal dosage of the additive is 1-3%
of the water present in the gas/water or gas/water/oil stream.
[0007] Kinetic Inhibition of the Formation of Gas Hydrates
[0008] Kinetic inhibitors are products which delay the initial
nucleation of gas hydrates. Kinetic inhibitors thus are only
effective for a limited period of time, which is a disadvantage.
These products normally are polymers, and several classes of
polymers suitable as kinetic inhibitors have been described in WO
93/25798.
[0009] Dispersion of Gas Hydrates
[0010] When dispersants are used, the formation of small crystals
of gas hydrates occurs, but the agglomeration of these crystals is
prevented. This is mainly expected to be due to adsorption of the
dispersant on the surfaces of initially formed crystals of gas
hydrate. The dispersants typically are surface-active agents i.e.
they contain at least one hydrophilic (polar) and at least one
hydrophobic (nonpolar, oleophilic) group. The dispersant will
adsorb with its polar end toward the gas hydrate crystal, turning
its nonpolar, hydrocarbon end outwards. The crystals thus are made
oleophilic and can easily be dispersed in the liquid hydrocarbon
phase. Dispersants thus are only effective when such a liquid oil
phase is present. This will normally be the case in the pipeline
from the production well to the first treatment station, when the
fluid stream contains both gas and oil as well as water. The
adsorbed layer of dispersants on the crystals will also prevent
them from growing together into large aggregates, which otherwise
may cause complete blockage of the pipe line. This property of the
dispersants has resulted in their usually being named
anti-agglomerants, and this term will be used throughout this
application.
[0011] In U.S. Pat. No. 4,915,176 a method of transporting a
hydrate forming fluid is disclosed, where an additive is injected
into the fluid for reducing the tendency to agglomeration of the
hydrates so as to obtain hydrates in the dispersed form. The
additives used in the working examples are fatty acid
diethanolamides having different alkyl chain lengths, sodium
dioctylsulfosuccinate, and sorbitan monolaurate.
[0012] In WO 96/34177 quaternary ammonium surfactants are described
where at least two butyl, pentyl or iso-pentyl groups are attached
to the nitrogen atom, which also carries one or two long alkyl
glycol ether chains. Some products with this configuration have
been shown to be good gas hydrate anti-agglomerants. Their main
drawback is that they are not readily biodegraded. The production
process for these types of compounds also contains several steps
and thus is rather time-consuming.
[0013] WO 03/008757 discloses alkoxylated quaternary ammonium
compounds containing ester groups as anti-agglomerants. These
compounds are not readily biodegradable either.
[0014] In U.S. Pat. No. 6,331,508 a method for controlling the
formation of gas hydrate crystals in a fluid mixture is disclosed,
where a polyoxyalkylenediamine is added to the mixture in an amount
effective to prevent and/or inhibit crystal growth. The preferred
compounds have the general formula
##STR00001##
[0015] wherein R is an alkyl group having 1-20 carbon atoms, x=1-4,
n=2 or 3, and b+f+g=3-30, preferably 20-30. In the working example
Ethoduomeen T/25 (ex Akzo Nobel) is used. This compound is a
N-(tallow alkyl)propylenediamine that has been reacted with 15
moles of ethylene oxide; thus this is a compound according to the
formula above wherein x is 3, n is 2, and b+f+g=15. Also
propoxylated compounds with b+f+g=30 were suggested. However,
propoxylated products containing large amounts of propylene oxide
units will exhibit a high log P.sub.ow (see further below for a
definition of log P.sub.ow), since the solubility in water will be
rather low, and further the biodegradability will be poor.
[0016] In U.S. Pat. No. 4,973,775 a process for delaying the
formation and/or reducing the agglomeration tendency of gas
hydrates is disclosed wherein hydroxy-carbylamides and
polyhydroxycarbylamides are used. Suggested compounds are described
by the general formulae (1), (2), and (3)
##STR00002##
[0017] wherein R--C.dbd.O is a radical of the carboxylic acid and
comprises 4 to 28 carbon atoms, R', R'', and R''' are hydroxycarbyl
radicals and R'''' is an alkylenic radical of the type
C.sub.nH.sub.2n, and n is a whole number equal to at least 1. Only
compounds according to formula (2) are disclosed, such as coconut
diethanolamide, ethoxylated coconut diethanolamide, rapeseed
diethanolamide or diethanolamides from other acids.
[0018] Although various options are provided to overcome the
problem of agglomeration, there is still a need for improved
anti-agglomerants for gas hydrates.
[0019] The aim of the present invention is to find new
anti-agglomerants for gas hydrates that are efficient in seawater,
brackish and/or fresh water, and have a better biodegradability and
are more economically attractive than previously known
compounds.
[0020] It has now surprisingly been found that a surface-active
non-quaternary nitrogen-containing compound with 1-5, preferably
1-4, more preferably 1-3, and most preferably 1 or 2 nitrogen
atoms, which compound has at least one hydrophobic group with 6-24,
preferably 8-22, and most preferably 8-18 carbon atoms, and where
the hydrophobic group is connected to the remainder of the molecule
by an amine moiety, an ether moiety or an amide moiety, provided
that when the hydrophobic group is connected by means of an amide
moiety to the remainder of the molecule, the compound must contain
a total of at least 2 nitrogen atoms;
[0021] which compound optionally contains 1-12, preferably 2-10
--CH.sub.2CH.sub.2O-- groups and/or 1-6 hydroxyalkyl groups with
3-4 carbon atoms; and which compound has at least one C2-C3,
preferably C2, acyl group and/or at least one hydroxyalkyl group
with 3-4 carbon atoms, preferably with 3 carbon atoms; which
compound is selected from the group below consisting of compounds
IA, IB, IC, II, and III, or a salt thereof;
[0022] is an efficient anti-agglomerant for gas hydrates in both
salt and fresh water and at the same time has a better
biodegradability than the prior art compounds. A further advantage
is that these compounds also have the ability to act as corrosion
inhibitors. According to an unproven theory, it is believed that
the essential acyl, hydroxypropyl, and hydroxybutyl groups have an
improved adhesion to the gas hydrate surface, and thereby
facilitate dispersion and prevent agglomeration.
[0023] The surface-active non-quaternary nitrogen-containing
compound is selected from the group of non-quaternary
nitrogen-containing compounds having the following general formulae
IA, IB, IC, II, and III, viz.
##STR00003##
[0024] wherein R is a C.sub.6-C.sub.24, preferably a
C.sub.8-C.sub.22, and most preferably a C.sub.8-C.sub.18
hydrocarbyl group; m is 2 or 3, preferably 3; a=0-4, preferably
0-3, and most preferably 0 or 1; b is at least 1 at each position;
.SIGMA.b on average is 2-12, preferably 2-10; c is 0 or 1; d on
average is 0-5, preferably 0; each A is independently selected from
H, --C(.dbd.O)CH.sub.3, --C(.dbd.O)CH.sub.2CH.sub.3, C1-C3 alkyl
groups, --[CH.sub.2CH(X)O], H, and --[CH.sub.2CH(X)O],
--C(.dbd.O)CH.sub.3, wherein X is --CH.sub.3 or --CH.sub.2CH.sub.3,
preferably --CH.sub.3, e is 1-3, and the sum of all e in the
molecule is at most 6 on average; provided that at least one of
groups A is --[CH.sub.2CH(X)O].sub.eH, --[CH.sub.2CH(X)O],
--C(.dbd.O)CH.sub.3, --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.2CH.sub.3;
##STR00004##
[0025] wherein B is independently selected from
--[CH.sub.2CH(X)O].sub.eH,
[0026] --[CH.sub.2CH(X)O].sub.e--C(.dbd.O)CH.sub.3 or H; each D is
independently selected from H, a hydrocarbyl group with 1-24 carbon
atoms, preferably 1-3 carbon atoms,
[0027] --[CH.sub.2CH(X)O], H or --[CH.sub.2CH(X)O],
--C(.dbd.O)CH.sub.3;
[0028] provided that at least one of groups D or group B is
[0029] --[CH.sub.2CH(X)O], H or --[CH.sub.2CH(X)O],
--C(.dbd.O)CH.sub.3;
[0030] m, a, c, e, .SIGMA.e and X are as defined for IA; and R is a
hydrocarbyl group with 6-24 carbon atoms, preferably 6-18, and most
preferably 6-15 carbon atoms, provided that when all D and B are a
group --[CH.sub.2CH(X)O], H, c=0, m=3, and a=1-4, then log P.sub.ow
for the molecule is at most 3.
##STR00005##
[0031] wherein R is a hydrocarbyl group having 6-24, preferably
8-22, and most preferably 8-18 carbon atoms; m is 2 or 3,
preferably 3; a=0-4, preferably 0-3, and most preferably 1; E is
C.sub.1-C.sub.3 alkyl, --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.2CH.sub.3; and F is --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.2CH.sub.3.
##STR00006##
[0032] wherein R'C(.dbd.O)-- is an acyl group with 6-24, preferably
8-22, and most preferably 8-18 carbon atoms; o=0-3, preferably 1-2;
p=0-3, preferably 0-2; .SIGMA.(o+p) on average is 0-6, preferably
1-4; m is 2 or 3, preferably 2; and each A is independently
selected from H, --[CH.sub.2CH(X)O], H, --[CH.sub.2CH(X)O],
--C(.dbd.O)CH.sub.3, --C(.dbd.O)CH.sub.3,
--C(.dbd.O)CH.sub.2CH.sub.3, and C1-C3 alkyl groups, provided that
at least one of groups A is --[CH.sub.2CH(X)O], H,
--[CH.sub.2CH(X)O], --C(.dbd.O)CH.sub.3, --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.2CH.sub.3, wherein X, e and .SIGMA.e have the
same meaning as for IA; and
##STR00007##
[0033] wherein r and s independently are 0-2 provided
.SIGMA.r+s=0-2; and j is 0 or 1, provided that when j=1, then c=0
and R''.dbd.R', and when j=0, then R''.dbd.R, and provided that at
least one of A is --[CH.sub.2CH(X)O], H, --[CH.sub.2CH(X)O],
--C(.dbd.O)CH.sub.3, --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.2CH.sub.3, wherein X, e, and .SIGMA.e have the
same meaning as for IA; R, c, d, b, .SIGMA.b, m, and A are as
defined for IA, and R'C(.dbd.O)-- is as defined for (II);
[0034] or a salt of any of compounds IA, IB, IC, II or III; or any
combination thereof.
[0035] Preferred structures of formula IA are those where all
groups A are --CH.sub.2CH(CH.sub.3)OH or those where all groups A
are --C(.dbd.O)CH.sub.3.
[0036] Thus, one embodiment of the invention comprises compounds
according to the formulae
##STR00008##
[0037] wherein R is a hydrocarbyl group of 6-24, preferably 8-22,
and most preferably 8-18 carbon atoms, m is 2 or 3, preferably 3, a
is 0 or 1, the sum of b on average is 2-6, and the sum of e is 2 or
3, and
##STR00009##
[0038] wherein R is a hydrocarbyl group of 6-24, preferably 8-22,
and most preferably 8-18 carbon atoms, m is 2 or 3, a is 0 or 1,
and the sum of b is 2-6.
[0039] Another embodiment comprises compounds having formula IB,
wherein R is a C.sub.6-C.sub.15 hydrocarbyl group, c is 0, m is 3,
a is 1, B and D are independently selected from the groups
--CH.sub.2CH(X)O], H and --[CH.sub.2CH(X)O], --C(.dbd.O)CH.sub.3,
and the sum of e on average is 3-6.
[0040] Preferred structures of formula IC are those wherein a=1,
the group F is --C(.dbd.O)CH.sub.3, and the group E is C1-C3 alkyl
or --C(.dbd.O)CH.sub.3.
[0041] Thus, a further embodiment of the invention comprises
compounds having the formula
##STR00010##
[0042] wherein R is an alkyl group having 6-24, preferably 8-22,
and most preferably 8-18 carbon atoms, m is 2 or 3, preferably 3,
and E is C1-C3 alkyl, preferably methyl, or
--C(.dbd.O)CH.sub.3.
[0043] Preferred surface-active non-quaternary nitrogen-containing
compounds of formula II are selected from the group of compounds
having the following general formulae
##STR00011##
[0044] wherein n is at least 1 at each position and .SIGMA.n on
average is 2-4, m is 2 or 3, preferably 2, R'(C.dbd.O)-- and A are
as defined for II except that X is --CH.sub.3, provided that at
least one of A is --[CH.sub.2CH(CH.sub.3)O], H,
[0045] --[CH.sub.2CH(CH.sub.3)O], --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.3, wherein e and .SIGMA.e are as defined for
II;
[0046] and
##STR00012##
[0047] wherein m is 2 or 3, preferably 2; R'(C.dbd.O)-- and A are
as defined for II except that X is --CH.sub.3, provided that at
least one of A is --[CH.sub.2CH(CH.sub.3)O], H,
[0048] --[CH.sub.2CH(CH.sub.3)O], --C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.3; wherein X, e, and .SIGMA.e have the same
meaning as for IA;
[0049] and salts of any of compounds IIA and IIB.
[0050] Thus, still another embodiment of the invention comprises
compounds IIA having the formula
##STR00013##
[0051] wherein R'(C.dbd.O)-- is an acyl group having 6-24,
preferably 8-22, and most preferably 8-18 carbon atoms, and m is 2
or 3, preferably 2;
[0052] and compounds IIB having the formula
##STR00014##
[0053] wherein R'(C.dbd.O)-- is an acyl group having 6-24,
preferably 8-22, and most preferably 8-18 carbon atoms, and m is 2
or 3, preferably 2.
[0054] Preferred surface-active non-quaternary nitrogen-containing
compounds of formula III have the formula
##STR00015##
[0055] wherein r and s independently are 0-1, preferably both r and
s are 0; R, b, .SIGMA.b, m, and A are as defined for IA except that
X is --CH.sub.3, provided that at least one of A is
--[CH.sub.2CH(CH.sub.3)O].sub.eH,
--[CH.sub.2CH(CH.sub.3)O].sub.e--C(.dbd.O)CH.sub.3 or
--C(.dbd.O)CH.sub.3, wherein e and .SIGMA.e are as defined for IA;
or a salt of IIIA.
[0056] Any combination of IA, IB, IC, IIA, IIB, and IIIA or their
salts may also be used.
[0057] The compounds having these formulae or their salts were
found to be biodegradable, efficient anti-agglomerants for gas
hydrates.
[0058] In a further embodiment, the anti-agglomerant has a low log
P.sub.ow (=log K.sub.ow), preferably .ltoreq.3, more preferably 2
or lower, since substances with a log P.sub.ow higher than 3 are
liable to bioaccumulate. This value can be either experimentally
measured or theoretically calculated, and is derived from the
partitioning of a compound between the two phases n-octanol and
water. The partition coefficient (P) is defined as the ratio of the
equilibrium concentrations of a dissolved substance in a two-phase
system consisting of two largely immiscible solvents; in the case
of n-octanol and water the P.sub.ow value (=the octanol-water
partition coefficient) of a compound is:
[0059] P.sub.ow=(C.sub.n-octanol/C.sub.water), where
C.sub.n-octanol and C.sub.water are the equilibrium concentrations
of the compound in the octanol and water phases, respectively. Due
to the emulsifying properties of many surfactants, log P.sub.ow
normally is theoretically calculated for these kinds of products.
For an introduction to the calculation of P.sub.ow see Annex to the
OECD Guideline for Testing of Chemicals 117 and references
therein.
[0060] For the compounds IB it is essential that log P.sub.ow is at
most 3.
[0061] The above compounds are obtainable by methods well known in
the art. Compounds of formula IA are obtainable by first
ethoxylating a suitable alkyl amine, alkyl polyamine, alkyl
etheramine or alkyl etherdiamine, such as a primary (fatty
alkyl)monoamine, (fatty alkyl)aminopropyl amine, 3-[(fatty
alkyl)oxy]propyl amine or N-[3-(fatty alkyl)oxy]-1,3-propane
diamine, and then propoxylating and/or butoxylating and/or
acetylating the ethoxylated product. The number of moles of
ethylene oxide reacting with the amine compound need not be an
integer and represents the number average degree of polymerization
of the ethylene oxide in the product (see Nonionic Surfactants:
Organic Chemistry in Surfactant Science Series Volume 72, 1998, p
1ff, edited by Nico M. van Os; Marcel Dekker, Inc). Products of
formula IA may be added to the water phase as such or as a salt
with an acid, preferably as a carboxylic acid salt thereof. Any
lower carboxylic acid salt is suitable, and acetic acid salts are
especially preferred. Also salts of IA with mineral acids may
suitably be used, such as the chlorides, sulfates, and
phosphates.
[0062] Compounds of formula IB are obtainable by propoxylating
and/or butoxylating a suitable alkyl amine, alkyl polyamine or
alkyl etheramine. Also here the product is preferably added as a
carboxylic acid salt, but salts with mineral acids are also
suitable for use.
[0063] Compounds of formula IC are obtainable by acetylating a
N-(fatty alkyl)-1,3-propylenediamine or N-(fatty alkyl), N-(C1-3
alkyl)-1,3-propylenediamine.
[0064] Compounds of formula IIA are obtainable by producing an
amide from a fatty acid and aminoethyl ethanolamine or aminopropyl
ethanolamine, ethoxylating the amide, and then propoxylating and/or
acetylating the ethoxylated amide.
[0065] Compounds of formula IIB are obtainable by producing an
amide from a fatty acid and aminoethyl ethanolamine or aminopropyl
ethanolamine and then directly propoxylating and/or acetylating the
amide. Also for both IIA and IIB the product is preferably added as
a salt.
[0066] Compounds of formula IIIA are obtainable by first
ethoxylating a suitable alkyl polyamine containing a tertiary
mono(fatty alkyl)amino group and then propoxylating and/or
acetylating the ethoxylated product. The product is preferably
added as a salt.
[0067] Suitable alkyl amines and alkyl polyamines that can be used
as starting materials for compounds of formulae IA and IB are
(fatty alkyl)monoamines according to formula R1NH.sub.2, wherein R1
is an aliphatic group having 6-24 carbon atoms; (fatty alkyl)
diamines according to formula R2NHCH.sub.2CH.sub.2CH.sub.2NH.sub.2,
wherein R2 is an aliphatic group having 6-24 carbon atoms (also
suitable as starting material for IC); and linear (fatty
alkyl)triamines according to formula
R3NHCH.sub.2CH.sub.2CH.sub.2NHCH.sub.2CH.sub.2CH.sub.2NH.sub.2,
wherein R3 is an aliphatic group having 6-24 carbon atoms.
[0068] Suitable alkyl etheramines or alkyl etherdiamines that can
be used as starting materials for compounds of formulae IA and IB
are alkyl etheramines according to formula
R4O(CH.sub.2CH.sub.2CH.sub.2)NH.sub.2 and alkyl etherdiamines
according to formula
R5O(CH.sub.2CH.sub.2CH.sub.2)NH(CH.sub.2CH.sub.2CH.sub.2)NH.sub.2,
wherein R4 and R5 are aliphatic groups having 6-24 carbon
atoms.
[0069] Suitable alkyl polyamines that can be used as starting
materials for compounds of formulae III and IIIA are branched
(fatty alkyl)triamines (Y-triamines) of formula
R6N(CH.sub.2CH.sub.2CH.sub.2NH.sub.2).sub.2, wherein R6 is an
aliphatic group having 6-24, preferably 8-22, carbon atoms, or
branched (fatty alkyl) pentaamines of formula
R7N(CH.sub.2CH.sub.2CH.sub.2NHCH.sub.2CH.sub.2CH.sub.2NH.sub.2).sub.2,
wherein R7 is an aliphatic group having 6-24, preferably 8-22
carbon atoms.
[0070] Suitable alkyl etherpolyamines that can be used as starting
materials for compounds of formula III are those of formula
[0071]
R8O(CH.sub.2CH.sub.2CH.sub.2)N(CH.sub.2CH.sub.2CH.sub.2NH.sub.2).su-
b.2, wherein R8 is an aliphatic group having 6-24, preferably 8-22
carbon atoms.
[0072] Examples of suitable fatty amines for use as starting
materials for compounds of formulae IA and IB are n-hexyl amine,
2-ethylhexyl amine, n-octyl amine, 2-propylheptyl amine, n-decyl
amine, n-dodecyl amine, (coco alkyl)amine, n-tetradecyl amine,
n-hexadecyl amine, n-octadecyl amine, oleyl amine, (tallow
alkyl)amine, (rapeseed alkyl)amine, (soya alkyl)amine, erucyl
amine, N-(n-decyl)-trimethylene diamine, N-(n-dodecyl)-trimethylene
diamine, N-(coco alkyl)-trimethylene diamine, N-(rapeseed
alkyl)-trimethylene diamine, N-(soya alkyl)-trimethylene diamine,
N-(tallow alkyl)-trimethylene diamine, N-erucyl trimethylene
diamine, N-(n-decyl)-N''-(3-aminopropyl)-1,3-propane diamine,
N-(n-dodecyl)-N''-(3-aminopropyl)-1,3-propane diamine, N-(coco
alkyl)-N''-(3-aminopropyl)-1,3-propane diamine, N-(rapeseed
alkyl)-N''-(3-aminopropyl)-1,3-propane diamine, N-(soya
alkyl)-N''-(3-aminopropyl)-1,3-propane diamine,
N-oleyl-N''-(3-aminopropyl)-1,3-propane diamine, N-(tallow
alkyl)-N''-(3-amino-propyl)-1,3-propane diamine,
N-erucyl-N''-(3-aminopropyl)-1,3-propane diamine,
N-(3-aminopropyl)-N''-[3-(9-decylamino)propyl]-1,3-propane diamine,
N-(3-aminopropyl)-N''-[3-(9-dodecylamino)propyl]-1,3-propane
diamine, N-(3-aminopropyl)-N''-[3-(9-(coco
alkyl)amino)propyl]-1,3-propane diamine,
N-(3-aminopropyl)-N''-[3-(9-(rapeseed
alkyl)amino)propyl]-1,3-propane diamine,
N-(3-aminopropyl)-N''-[3-(9-(soya alkyl)amino)propyl]-1,3-propane
diamine,
N-(3-aminopropyl)-N''-[3-(9-octadecenylamino)propyl]-1,3-propane
diamine, N-(3-aminopropyl)-N''-[3-(9-(tallow
alkyl)amino)propyl]-1,3-propane diamine, and
N-(3-aminopropyl)-N''-[3-(9-erucylamino)propyl]-1,3-propane
diamine.
[0073] Examples of suitable fatty diamines for use as starting
materials for compounds of formula IC are
N-(2-ethylhexyl)-trimethylene diamine, N-(n-octyl)-trimethylene
diamine, N-(n-decyl)-trimethylene diamine,
N-(n-dodecyl)-trimethylene diamine, N-(n-tetradecyl)-trimethylene
diamine, N-(coco alkyl)-trimethylene diamine,
N-(n-hexadecyl)-trimethylene diamine, N-oleyl-trimethylene diamine,
N-(rapeseed alkyl)-trimethylene diamine, N-(soya
alkyl)-trimethylene diamine, N-(tallow alkyl)-trimethylene diamine,
N-erucyl-trimethylene diamine, N-(n-octyl)-N-methyl
aminopropylamine, N-(2-ethylhexyl)-N-methyl aminopropylamine,
N-(n-decyl)-N-methyl aminopropylamine, N-(n-dodecyl)-N-methyl
aminopropylamine, N-(coco alkyl)-N-methyl aminopropylamine,
N-(n-tetradecyl)-N-methyl amino-propylamine, N-oleyl-N-methyl
aminopropylamine, N-(rapeseed alkyl)-N-methyl aminopropylamine,
N-(soya alkyl)-N-methyl aminopropylamine, and N-(tallow
alkyl)-N-methyl aminopropylamine.
[0074] Examples of suitable alkyl etheramines and alkyl
etherdiamines for use as starting materials for compounds of
formulae IA and IB are 3-(n-octyloxy)propyl amine,
3-[2-(ethylhexyl)oxy]propyl amine, 3-(n-decyloxy)propyl amine,
3-[2-(propylheptyl)oxy]propyl amine, 3-(dodecyloxy)propyl amine,
3-[(coco alkyl)oxy]propyl amine, 3-[(rapeseed alkyl)oxy]propyl
amine, 3-[(soya alkyl)oxy]propyl amine, 3-(octadecenyloxy)propyl
amine, 3-[(tallow alkyl)oxy]-propyl amine, 3-(erucyloxy)propyl
amine, N-[3-(2-(ethylhexyl)oxy)propyl]-1,3-propane diamine,
N-[3-(n-octyloxy)propyl]-1,3-propane diamine,
N-[3-(n-decyloxy)propyl]-1,3-propane diamine,
N[3-(2-(propylheptyl)oxy)propyl]-1,3-propane diamine,
N[3-(tridecyloxy)propyl]-1,3-propane diamine, and ether mono- and
diamines based on C.sub.6-C.sub.24 alcohols that have been
ethoxylated with up to 5 moles of ethylene oxide.
[0075] Examples of fatty acids for use as starting materials for
the amides of compounds of formulae II, IIA, IIB, and III are
hexanoic acid, 2-ethylhexanoic acid, n-octanoic acid, n-decanoic
acid, n-dodecanoic acid, coco fatty acid, oleic acid, rapeseed
fatty acid, soya fatty acid, tallow fatty acid, tall oil fatty
acid, and erucic acid.
[0076] Examples of (fatty alkyl)polyamines that can be used as
starting materials for compounds of formulae III and IIIA are
N,N-bis(3-aminopropyl)hexyl amine,
N,N-bis(3-aminopropyl)(2-ethylhexyl)amine,
N,N-bis(3-aminopropyl)n-octyl amine, N,N-bis(3-aminopropyl)decyl
amine, N,N-bis(3-aminopropyl)(2-propyl-heptyl)amine,
N,N-bis(3-aminopropyl)dodecyl amine, N,N-bis(3-aminopropyl)-(coco
alkyl)amine, N,N-bis(3-aminopropyl)tetradecyl amine,
N,N-bis(3-amino-propyl)hexadecyl amine,
N,N-bis(3-aminopropyl)stearyl amine,
N,N-bis(3-aminopropyl)(rapeseed alkyl)amine,
N,N-bis(3-aminopropyl)(tallow alkyl)amine,
N,N-bis(3-aminopropyl)(soya alkyl)amine,
N,N-bis(3-aminopropyl)oleyl amine, and N,N-bis(3-aminopropyl)erucyl
amine.
[0077] Examples of (fatty alkyl)etherpolyamines that can be used as
starting materials for compounds of formula III are
N-[3-(n-octyloxy)propyl]-N,N-bis(3-amino-propyl)amine,
N-[3-(n-dodecyloxy)propyl]-N,N-bis(3-aminopropyl)amine,
N-[3-(tridecyloxy)propyl]-N,N-bis(3-aminopropyl)amine,
N-[3-[(tallow alkyl)oxy)]-propyl]-N,N-bis(3-aminopropyl)amine, and
N-[3-(octadecenyloxy)propyl]-N,N-bis(3-aminopropyl)amine.
[0078] The acylation reaction can be performed with an acid, an
acid anhydride or an acyl chloride. The acetylation reaction is
most conveniently performed with acetic anhydride, but also, e.g.,
acetic acid or acetyl chloride may be used. The ethoxylation and
propoxylation reactions are well known in the art. Normally all
primary and secondary amino groups are alkoxylated in a first step
in the absence of any catalyst, to obtain amino groups fully
substituted by hydroxyalkyl groups, i.e. normally no hydrogens
remain on the nitrogen atoms. If further alkylene oxide is to be
added, typically an alkali metal hydroxide is used as a catalyst,
preferably KOH. However, the choice of catalyst is not critical,
and there are many catalysts known to the person skilled in the art
that could equally well be used. Wherever the degree of
alkoxylation is discussed, the numbers referred to are molar
average numbers.
[0079] The present invention also relates to a method for
inhibiting the agglomeration of gas hydrates in a conduit, where
the conduit contains a flowing mixture comprising hydrocarbons with
1-4 carbon atoms and water and where hydrates are formed from the
hydrocarbons and water, the method comprising the steps: [0080] a)
adding to the mixture an anti-agglomerant as defined in formulae
IA, IB, IC, II, and III in an amount that is effective to inhibit
the agglomeration of hydrates at the prevailing temperature and
pressure in the conduits; [0081] b) flowing the mixture containing
the anti-agglomerant through the conduit.
[0082] The concentrations of the anti-agglomerants are at least
0.05%, preferably at least 0.5%, by weight of the water phase, and
at most 10%, preferably at most 5%, and most preferably at most 3%,
by weight of the water phase. The exact amount of anti-agglomerant
to be used depends, inter alia, on the structure of the
anti-agglomerant, the water quality, the pressures applied, and the
actual composition of the gas and/or oil. The anti-agglomerants of
the invention in addition to their dispersing ability also have
other useful properties, such as corrosion inhibiting ability. The
anti-agglomerant is preferably added in the well head in a
composition that may also contain other corrosion inhibitors and
paraffin deposition inhibitors. Such a composition suitably
contains [0083] a) 1 part by weight of the gas hydrate
anti-agglomerant as defined in formulae IA, IB, IC, II, and III,
and [0084] b) 0.0001-0.1, preferably 0.001-0.05 parts by weight of
a corrosion inhibitor and/or a paraffin deposition inhibitor.
[0085] In a final embodiment of the invention, the present
anti-agglomerant is used in combination with other compounds that
are used in compositions wherein gas hydrates are potentially
formed, such as corrosion inhibitors and other additives. Examples
of suitable corrosion inhibitors are tallow amines, N-(tallow
alkyl)-trimethylene diamines, imidazolines, and quaternary amines,
and examples of suitable paraffin deposition inhibitors are alcohol
esters of alpha-olefin maleic anhydride copolymers, ethylene vinyl
acetate copolymers, and alcohol esters of polyacrylic acid. Other
additives that may be present in the compositions are foam
depressors, such as silicone-containing compounds, glycol and
polyglycols, kinetic inhibitors, such as the polymers or
co-polymers of N-vinyl-2-pyrrolidone as described in WO
1993/025798, biocides, metal complexants, such as citric acid,
solubilizing agents, and additives for stabilizing the dispersion,
as well as other dispersants.
[0086] The following embodiments illustrate the invention and
should not be construed as limiting the scope thereof.
EXAMPLES
[0087] General
[0088] The technique used for evaluating the anti-agglomerants is
described in detail in "New Technique for Evaluating
Antiagglomerate Gas-Hydrate Inhibitors in Oilfield Applications",
SPE 93075, 2005 SPE International Symposium on Oilfield Chemistry,
Houston, Tex., February 2-4.
[0089] Principle: The complete multicell system consists of a
high-pressure vessel containing the multicell test unit, a cooling
unit, a stirrer drive, a sensor interface unit, and a computer
system. The high-pressure vessel is connected to two gas cylinders
containing pressurized hydrocarbon gas (87.9% methane, 7.7% ethane,
3.1% propane, and 1.3% isobutane) and nitrogen. Thus, in an
experimental run each test cell will be subjected to the same gas
mixture, temperature, and pressure. Each cell has a magnetic bar
stirrer and the rotation of the stirrer is monitored by the sensor
and recorded. When gas hydrate crystals are formed in a cell, there
will be a change in viscosity or flow behaviour and there will be a
change in the lag of the stirrer bar. Each time the magnetic bar
passes a certain point, an optical pulse is recorded. The lag is
measured as the difference between the position of the lower drive
magnets and the stirrer in the cell. When the viscosity gets too
high, as is the case when larger aggregates of gas hydrates are
formed, the magnetic stirrer will either stop completely, in which
case the signal will be zero, or start "skipping", which will
create an unstable/random signal, and this will be shown in the
recorded graph.
[0090] Each cell is also equipped with a temperature sensor.
[0091] In the Tables of Examples 1 and 2 below the following
notations have been used.
[0092] EO=ethyleneoxy unit
[0093] PO=propyleneoxy unit
[0094] 0=the compound does not work as an anti-agglomerant
[0095] 1=the compound initially works as an anti-agglomerant, but
not throughout the whole test
[0096] 2=the compound works as an anti-agglomerant throughout the
whole test (for notations 0, 1, and 2, see further explanations in
Example 2)
[0097] -=test not performed
Example 1
[0098] In Table 1 the results from multicell screening of some
anti-agglomerants are collected.
[0099] The cells are loaded with 1 ml of water/inhibitor mixture
and 2.5 ml of Sleipner condensate (=crude oil obtained from the
Sleipner oilfield of Statoil). Nitrogen is first applied to expel
most of the air, and then hydrocarbon gas is admitted until a
constant pressure of 100 bars is reached.
[0100] During the whole test, the mixtures were continuously
stirred at 120 rpm. The temperature was first lowered from about
20.degree. C. to 4.degree. C. in about 1.5 hours, then kept at
4.degree. C. for about two hours, and finally reheated again to
20.degree. C. in about 1.5 hours. When the stirrer works all the
time, the compound is considered to work well as an
anti-agglomerant, whereas if the stirrer bar stops, the compound is
considered not to work as an anti-agglomerant during the prevailing
conditions. The tests were performed both in seawater and in fresh
water and at different concentrations of the anti-agglomerants.
TABLE-US-00001 TABLE 1 Tests multicell screening Seawater Fresh
water Compound 1.0% 1.5% 1.5% 2.5% A. Oleyl amine + 2EO + 2PO,
quaternized with CH.sub.3Cl -- 2 0 -- (Comparison) B. (Coco
alkyl)amine + 2EO (Comparison) 0 0 -- -- C. (Coco alkyl)amine + 4
EO; acetic acid salt 0 0 -- -- (Comparison) D. Oleyl amine + 2EO;
acetic acid salt (Comparison) 0 -- -- -- 1. Oleyl amine + 2EO +
2PO; acetic acid salt -- 2 -- -- 2. Erucyl amine + 2EO + 2PO;
acetic acid salt -- 2 2 -- 3. (Coco alkyl)amine + 2EO + 2PO; acetic
acid salt 2 2 -- -- 4. N-(n-octyl)-trimethylene diamine + 3PO;
acetic acid -- 2 -- -- salt (log Pow = 0.84)* 5. Oleyl amine + 2EO,
diester with acetic acid; acetic 0 2 0 0 acid salt 6.
N-oleyl-trimethylene diamine + 3EO, triesterified with -- 2 -- 2
acetic anhydride; acetic acid salt 7. Monoamide between oleic acid
and aminoethyl 2 -- -- -- ethanolamine + 1EO, diesterified with
acetic anhydride; acetic acid salt 8. Monoamide between oleic acid
and aminoethyl 2 2 2 -- ethanolamine, amidated with acetic
anhydride 9. N,N-bis(3-aminopropyl)(tallow alkyl)amine, 0 2 -- --
diamidated with acetic anhydride 10. N-oleyl-trimethylene diamine
diamidated with acetic -- 2 -- -- anhydride 11.
N-(n-octyl)-trimethylene diamine di-amidated with -- 2 -- -- acetic
anhydride 12. N-(coco alkyl)-trimethylene diamine diamidated with
-- 2 -- -- acetic anhydride 13. N-(tallow alkyl)-N-methyl
aminopropylamine -- 2 -- -- monoamidated with acetic anhydride *the
log P.sub.ow values in Tables 1 and 2 were calculated using Models
developed by the U.S. EPA Office of Pollution Prevention and Toxics
and the Syracuse Research Corporation (U.S. EPA (United States
Environmental Protection Agency). 2004. Estimation Program
Interface (EPI) Suite (EPISuite.TM.) Version 3.12, Aug. 17,
2004).
[0101] The products according to the invention are at least as good
or better anti-agglomerants in the screening test than the
references A, B, C, and D and at the same time more easily
biodegradable than A. Note also that the references B and C, which
are (coco alkyl)amine ethoxylates, are not effective in this test
as anti-agglomerants for gas hydrates, whereas product 3, which is
a (coco alkyl)amine that has first been ethoxylated and then
propoxylated, works excellently as an anti-agglomerant.
Example 2
[0102] In Table 2 the results from multicell shut-in and restart of
some anti-agglomerants are collected. This test is more challenging
than the test in Example 1.
[0103] The cells are loaded in the same way as above, but
hydrocarbon gas is admitted until the constant stated pressure is
reached.
[0104] In this experiment the test cells were stirred at 120 rpm
for one hour at 20.degree. C. and the stated pressure. The stirring
was then stopped and the autoclave cooled to 4.degree. C. in about
1.5 hours. The cells were then kept at 4.degree. C. for a minimum
of twelve hours before the driving magnets were restarted at 120
rpm. They were then kept running for about two hours at 4.degree.
C. before the cells were reheated to 20.degree. C. in about 1.5
hours.
[0105] Three different events could then be observed: [0106] The
stirrer did not start at all until the temperature had been
increased so much that the gas hydrate had melted, which normally
happened at about 15.degree. C. This is marked as 0 in the tables.
[0107] The stirrer started but stopped again after a short period.
This is marked as 1 in the tables. [0108] The stirrer started and
kept on running continuously. This is marked as 2 in the
tables.
TABLE-US-00002 [0108] TABLE 2 Tests multicell shut-in Seawater
Fresh water (70 bar) (70 bar) Compound 1.5% 2.5% 2.0% 2.5% 1. Oleyl
amine + 2EO + 2PO; acetic 2** 1 1 1 acid salt 3. (Coco alkyl)amine
+ 2EO + 2PO; 0 1 2 -- acetic acid salt 6. N-oleyl-trimethylene
diamine + 0 1 -- 2 3EO, triesterified with acetic anhydride; acetic
acid salt 10. N-oleyl-trimethylene diamine 0 2 -- 2 diamidated with
acetic anhydride 14. N-(2-ethylhexyl)-trimethylene 0 0 -- 2
diamine, diamidated with acetic anhydride 15.
N-(2-ethylhexyl)-trimethylene -- 2 -- 1 diamine + 3PO; acetic acid
salt (log Pow* = 0.77) *the log P.sub.ow values in Tables 1 and 2
were calculated using Models developed by the U.S. EPA Office of
Pollution Prevention and Toxics and the Syracuse Research
Corporation (U.S. EPA (United States Environmental Protection
Agency). 2004. Estimation Program Interface (EPI) Suite (EPISuite
.TM.) Version 3.12, Aug. 17, 2004). **measured at 100 bar
[0109] The anti-agglomerants according to the invention have an
essential anti-agglomerating effect in sea-, brackish and/or fresh
water and at the same time are more easily biodegradable.
* * * * *