U.S. patent application number 15/584389 was filed with the patent office on 2017-11-09 for succinimide-based copolymers and use as hydrate inhibitors.
This patent application is currently assigned to Saudi Arabian Oil Company. The applicant listed for this patent is King Fahd University of Petroleum and Minerals, Saudi Arabian Oil Company. Invention is credited to Hassan Al-Ajwad, Mohammed Al-Daous, Abdullah Al-Malki, Rashed Alessa, Shaikh Asrof Ali, Mohamed Elanany, Khalid Majnouni.
Application Number | 20170321012 15/584389 |
Document ID | / |
Family ID | 59337816 |
Filed Date | 2017-11-09 |
United States Patent
Application |
20170321012 |
Kind Code |
A1 |
Elanany; Mohamed ; et
al. |
November 9, 2017 |
SUCCINIMIDE-BASED COPOLYMERS AND USE AS HYDRATE INHIBITORS
Abstract
Copolymers having General Formula (I): ##STR00001## in which
R.sup.1 is chosen from divalent C.sub.4-C.sub.7 aliphatic groups
and divalent C.sub.4-C.sub.7 heteroaliphatic groups, optionally
substituted with one or more C.sub.1-C.sub.6 aliphatic groups,
heteroatoms independently chosen from O, N, and S, or combinations
thereof, where: the divalent C.sub.4-C.sub.7 heteroaliphatic groups
include one or two heteroatoms independently chosen from O, N, and
S, and the maximum number of heteroatoms in R.sup.1 is two; x is a
molar fraction range chosen from 0.05 to 0.95; and y is a molar
fraction range chosen from 0.05 to 0.95, where the summation of x
and y equals 1. Methods for inhibiting formation of clathrate
hydrates in a fluid capable of forming the clathrate hydrates. The
methods include contacting the fluid with at least one copolymer of
General Formula (I) under conditions suitable for forming the
clathrate hydrates.
Inventors: |
Elanany; Mohamed; (Ras
Tanura, SA) ; Majnouni; Khalid; (Dhahran, SA)
; Alessa; Rashed; (Alkubar, SA) ; Al-Malki;
Abdullah; (Dhahran, SA) ; Al-Ajwad; Hassan;
(Dhahran, SA) ; Al-Daous; Mohammed; (Dhahran,
SA) ; Ali; Shaikh Asrof; (Dhahran, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Saudi Arabian Oil Company
King Fahd University of Petroleum and Minerals |
Dhahran
Dhahran |
|
SA
SA |
|
|
Assignee: |
Saudi Arabian Oil Company
Dhahran
SA
King Fahd University of Petroleum & Minerals
Dhahran
SA
|
Family ID: |
59337816 |
Appl. No.: |
15/584389 |
Filed: |
May 2, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62332768 |
May 6, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08K 5/36 20130101; C08K
5/04 20130101; C08G 73/02 20130101; C10L 3/107 20130101; C08G
73/1092 20130101; C08K 5/01 20130101; C08K 5/34 20130101; C08K 5/16
20130101; C08K 5/07 20130101 |
International
Class: |
C08G 73/10 20060101
C08G073/10; C08K 5/34 20060101 C08K005/34; C08K 5/07 20060101
C08K005/07; C08G 73/02 20060101 C08G073/02; C08K 5/04 20060101
C08K005/04; C08K 5/01 20060101 C08K005/01; C08K 5/36 20060101
C08K005/36; C08K 5/16 20060101 C08K005/16 |
Claims
1. A copolymer having General Formula (I): ##STR00038## in which:
R.sup.1 is chosen from divalent C.sub.4-C.sub.7 aliphatic groups
and divalent C.sub.4-C.sub.7 heteroaliphatic groups, optionally
substituted with one or more C.sub.1-C.sub.6 aliphatic groups,
heteroatoms independently chosen from O, N, and S, or combinations
thereof, where: the divalent C.sub.4-C.sub.7 heteroaliphatic groups
comprise one or two heteroatoms independently chosen from O, N, and
S, and the maximum number of heteroatoms in R.sup.1 is two; x is a
molar fraction range chosen from 0.05 to 0.95; and y is a molar
fraction range chosen from 0.05 to 0.95, where the summation of x
and y equals 1.
2. The copolymer of claim 1, where R.sup.1 is chosen from divalent
C.sub.4-C.sub.6 linear aliphatic groups.
3. The copolymer of claim 1, where R.sup.1 is substituted with one
or more C.sub.1-C.sub.3 linear aliphatic groups, C.sub.1-C.sub.3
branched aliphatic groups, or combinations thereof.
4. The copolymer of claim 1, where R.sup.1 is substituted with one
heteroatom independently chosen from O, N, and S.
5. The copolymer of claim 1, where: R.sup.1 is substituted with one
heteroatom, and the one heteroatom is O.
6. The copolymer of claim 1, where ##STR00039## is chosen from
##STR00040##
7. The copolymer of claim 1, where: x is a molar fraction range of
from 0.15 to 0.85 and y is a molar fraction range of from 0.15 to
0.85.
8. The copolymer of claim 1, where: ##STR00041## is chosen from
##STR00042## x is a molar fraction range of from 0.3 to 0.7 and y
is a molar fraction range of from 0.3 to 0.7.
9. The copolymer of claim 1, where the viscosity average molecular
weight of the copolymer is in the range of from 1,000 g/mol to
20,000 g/mol.
10. A method for inhibiting formation of clathrate hydrates in a
fluid capable of forming the clathrate hydrates, the method
comprising: contacting the fluid with at least one copolymer of
General Formula (I) under conditions suitable for forming the
clathrate hydrates: ##STR00043## in which: R.sup.1 is chosen from
divalent C.sub.4-C.sub.7 aliphatic groups and divalent
C.sub.4-C.sub.7 heteroaliphatic groups, optionally substituted with
one or more C.sub.1-C.sub.6 aliphatic groups, heteroatoms
independently chosen from O, N, and S, or combinations thereof,
where: the divalent C.sub.4-C.sub.7 heteroaliphatic groups comprise
one or two heteroatoms independently chosen from O, N, and S, and
where the maximum number of heteroatoms in R.sup.1 is two; x is a
molar fraction range chosen from 0.05 to 0.95; and y is a molar
fraction range chosen from 0.05 to 0.95, where the summation of x
and y equals 1.
11. The method of claim 10, where the fluid comprises water host
molecules and natural gas guest molecules chosen from methane,
ethane, propane, butane, pentane, carbon dioxide, hydrogen sulfide,
nitrogen, condensate thereof, or combinations thereof.
12. The method of claim 10, where: the clathrate hydrates comprise
SI clathrate hydrates, SII clathrate hydrates, SH clathrate
hydrates, or combinations thereof, and the contacting inhibits
formation of the SI clathrate hydrates, the SII clathrate hydrates,
the SH clathrate hydrates, or the combinations thereof.
13. The method of claim 10, where the contacting inhibits the
formation of the clathrate hydrates at a first subcooling
temperature of from 0.degree. C. to 4.0.degree. C.
14. The method of claim 10, where the contacting inhibits the
formation of the clathrate hydrates at a second subcooling
temperature of from 4.0.degree. C. to 10.0.degree. C.
15. The method of claim 10, where the contacting inhibits the
formation of the clathrate hydrates in a pressure range of from 40
bars to 200 bars.
16. The method of claim 10, where the fluid is contacted with a
composition comprising the at least one copolymer of General
Formula (I) and one or more additives, corrosion inhibitors, scale
inhibitors, thermodynamic hydrate inhibitors, low dose hydrate
inhibitors, anti-agglomerates, solvents, or combinations
thereof.
17. The method of claim 10, where: R.sup.1 is chosen from divalent
C.sub.4-C.sub.6 linear aliphatic groups and divalent
C.sub.4-C.sub.6 linear heteroaliphatic groups, x is a molar
fraction range of from 0.15 to 0.85 and y is a molar fraction range
of from 0.15 to 0.85.
18. The method of claim 10, where: ##STR00044## is chosen from
##STR00045## x is a molar fraction of 0.5, and y is a molar
fraction of 0.5.
19. The method of claim 10, where the fluid is contacted with the
at least one copolymer at a tie-in platform.
20. The method of claim 10, where the fluid is flowing in a
pipeline.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/332,768, filed May 6, 2016, which is
incorporated by reference in its entirety.
TECHNICAL FIELD
[0002] The present disclosure generally relates to
succinimide-based copolymers, to methods for synthesizing
copolymers, and to methods for inhibiting formation of clathrate
hydrates.
BACKGROUND
[0003] Conditions favoring formation of clathrate hydrates are
often found in pipelines. With the expansion of offshore gas
exploration and production, the formation of clathrate hydrates has
become a serious operational concern in both gas transportation and
gas processing. Agglomeration and adherence of clathrate hydrates
to pipeline walls can reduce gas production, plug sections of the
pipeline, and even block the pipeline, thereby leading to a
pipeline shutdown. In order to maintain gas production and avoid
pipeline shutdown, clathrate hydrate inhibitors have been added to
pipeline fluids.
[0004] Commercially available clathrate hydrate inhibitors include
thermodynamic hydrate inhibitors (that is, THIs), which act to
modify the conditions at which clathrate hydrates form in pipeline
fluids. For example, THIs may be added to pipeline fluids at high
concentrations (for example, up to 0.8 weight/weight, that is w/w
of the water cut) to modify the pressure, temperature, or a
combination of the pressure and temperature at which clathrate
hydrates form. Ethylene glycol (that is, monoethylene glycol or
MEG) and methanol are examples of THIs. Another type of
commercially available clathrate hydrate inhibitors are low dose
hydrate inhibitors (that is, LDHIs), which act to: (1) kinetically
delay clathrate hydrate nucleation, and (2) inhibit clathrate
hydrate growth. With regard to kinetically delaying clathrate
hydrate nucleation, LDHIs may interact with clathrate hydrate
nuclei during early formation of clathrate hydrates. With regard to
inhibiting clathrate hydrate growth, LDHIs may inhibit clathrate
hydrate growth by binding to a surface of the clathrate hydrate.
Poly(N-vinylcaprolactam) and poly(N-methyl-N-vinylacetamide) are
examples of LDHIs. A third type of commercially available clathrate
hydrate inhibitors are anti-agglomerates (that is, AAs), which act
to inhibit clathrate hydrate agglomeration. With regard to
inhibiting clathrate hydrate agglomeration, AAs may inhibit
clathrate hydrate agglomeration by adsorbing to clathrate hydrates
to prevent massive accumulation of clathrate hydrates. In one or
more embodiments, AAs may inhibit clathrate hydrate agglomeration
such that clathrate hydrates are kept in the form of a suspension.
Examples of AAs are anti-agglomerates based on quaternary ammonium
cations.
[0005] Recently, THIs have been replaced by commercially available
LDHIs, because THIs are viewed as being difficult to separate from
pipeline fluids, are harmful to the environment, and require high
concentrations to be effective. However, commercially available
LDHIs are also imperfect in that some are inefficient or
incompatible with other additives, for example, corrosion
inhibitors. Further, commercially available LDHIs which are capable
of inhibiting clathrate hydrates having a structure (Type) I (that
is, SI) crystalline structure under severe conditions, for example,
extreme subcooling temperatures and pressure, are limited.
Moreover, commercially available LDHIs, which are capable of
inhibiting clathrate hydrates having a SI crystalline structure,
are limited to a narrow subcooling temperature range. Also, AAs are
imperfect in that they fail to inhibit formation of clathrate
hydrates.
SUMMARY
[0006] In view of the Background, there is an ongoing need for
clathrate hydrate inhibitors and for methods of inhibiting
clathrate hydrate formation. Embodiments of the present disclosure
are directed to copolymers having General Formula (I):
##STR00002##
in which: R.sup.1 is chosen from divalent C.sub.4-C.sub.7 aliphatic
groups and divalent C.sub.4-C.sub.7 heteroaliphatic groups,
optionally substituted with one or more C.sub.1-C.sub.6 aliphatic
groups, heteroatoms independently chosen from O, N, and S, or
combinations thereof, where: the divalent C.sub.4-C.sub.7
heteroaliphatic groups include one or two heteroatoms independently
chosen from O, N, and S, and the maximum number of heteroatoms in
R.sup.1 is two; x is a molar fraction range chosen from 0.05 to
0.95; and y is a molar fraction range chosen from 0.05 to 0.95,
where the summation of x and y equals 1.
[0007] Embodiments of the present disclosure are also directed to
methods for inhibiting formation of clathrate hydrates in a fluid
capable of forming the clathrate hydrates. The methods include
contacting the fluid with at least one copolymer of General Formula
(I) under conditions suitable for forming the clathrate
hydrates:
##STR00003##
in which: R.sup.1 is chosen from divalent C.sub.4-C.sub.7 aliphatic
groups and divalent C.sub.4-C.sub.7 heteroaliphatic groups,
optionally substituted with one or more C.sub.1-C.sub.6 aliphatic
groups, heteroatoms independently chosen from O, N, and S, or
combinations thereof, where: the divalent C.sub.4-C.sub.7
heteroaliphatic groups include one or two heteroatoms independently
chosen from O, N, and S, and the maximum number of heteroatoms in
R.sup.1 is two; x is a molar fraction range chosen from 0.05 to
0.95; and y is a molar fraction range chosen from 0.05 to 0.95,
where the summation of x and y equals 1.
[0008] Additional features and advantages of the described
embodiments in this disclosure will be set forth in the Detailed
Description which follows, and in part will be readily apparent to
those skilled in the art from that description or recognized by
practicing the embodiments described in this disclosure, including
the Detailed Description which follows, the claims, as well as the
appended drawings.
[0009] It is to be understood that both the foregoing general
description and the following Detailed Description describe various
embodiments and are intended to provide an overview or framework
for understanding the nature and character of the claimed subject
matter. The accompanying drawings are included to provide a further
understanding of the various embodiments, and are incorporated into
and constitute a part of this disclosure. The drawings illustrate
the various embodiments described in this disclosure, and together
with the Detailed Description serve to explain the principles and
operations of the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a proton nuclear magnetic (that is, .sup.1H NMR)
spectrum of succinimide-based copolymers having structure (SBC-1)
as disclosed in Table 1, where Chemical Shift .delta. [parts per
million, that is ppm]=1.6-2.0 belongs to the 4 hydrogen atoms
marked f and has an integrated area (A), where the 2 hydrogen atoms
marked d and the 4 hydrogen atoms marked e have an integrated area
(B) (where B=[A/4]*6), where the 2 hydrogen atoms marked b have an
integrated area (C) which would be calculated as (D-[A/4]*6), where
D represents the total area belonging to the hydrogen atoms marked
b, d, and e under .delta.2.4-3.7 ppm, where the mole ratio of the
monomeric repeating units is calculated as (C/2):(A/4), based on
the ratio of a single hydrogen atom of the first and second
monomeric repeating units, and where dashed lines are depicted for
estimating via integration the number of protons associated with
spectrum peaks;
[0011] FIG. 2 is a resonance .sup.1H NMR spectrum of
succinimide-based copolymers having structure (SBC-2) as disclosed
in Table 1, where Chemical Shift .delta. [ppm]=1.6-1.8 belongs to
the 6 hydrogen atoms marked f and g and has an integrated area of
(A), where the 2 hydrogen atoms marked d and the 4 hydrogen atoms
marked e should have an integrated area equal to area A, where the
2 hydrogen atoms marked b should have an integrated area of (B)
which would be calculated as (B=C-A), where C represents the total
area belonging to the hydrogen atoms marked b, d, and e under
.delta.2.3-3.6 ppm, and where the mole ratio of the monomeric
repeating units is calculated as (B/2):(A/6), based on the ratio of
a single hydrogen atom of the first and second monomeric repeating
units;
[0012] FIG. 3 is a .sup.1H NMR spectrum of succinimide-based
copolymers having structure (SBC-3) as disclosed in Table 1, where
Chemical Shift .delta. [ppm]=1.2-1.7 ppm belongs to the 8 hydrogen
atoms marked f and g and has an integrated area of (A), where the 2
hydrogen atoms marked d and the 4 hydrogen atoms marked e should
have an integrated area (B) which would be calculated as
(B=[A/8]*6), where the 2 hydrogen atoms marked b would have an
integrated area of (C) which would then be calculated as (C=[D-B]),
where D represents the total area belonging to the hydrogen atoms
marked b, d, and e under .delta.2.3-3.5 ppm, and where the mole
ratio of the monomeric repeating units is calculated as
(C/2):(A/8), based on the ratio of a single hydrogen atom of the
first and second monomeric repeating units;
[0013] FIG. 4 is a graph of Time (Minutes) with respect to Pressure
(Bars) of a 2% poly-ethyl-oxazoline (that is, 2% PEOx) composition,
a 2% polyacrylamide-co-acrylic acid (that is, 2% PAC-AA)
composition, and Brine as disclosed in Table 2 (that is, Control).
FIG. 4 is also a graph of Time (Minutes) with respect to
Temperature (.degree. C.) of Rocking Cells RC-5 (that is, RC
Temperature), where the Temperature (degrees Celsius, that is
.degree. C.) of the Rocking Cells RC-5 is programmed to change in
three stages in accordance with the Starting Temperature (.degree.
C.), Average Ramp (.degree. C./minute) and Duration (Minutes) as
set forth in Table 4;
[0014] FIG. 5 is a graph of Time (Minutes) with respect to Pressure
(Bar) of succinimide-based copolymers having structures (SBC-4)
(that is, KHI-5), (SBC-1) (that is, KHI-6), (SBC-2) (that is,
KHI-7), and (SBC-3) (that is KHI-8) as disclosed in Table 1, and
Brine as disclosed in Table 2 (that is, Control). FIG. 5 is also a
graph of Time (Minutes) with respect to Temperature (.degree. C.)
of Rocking Cells RC-5 (that is, RC Temperature), where the
Temperature (.degree. C.) of the Rocking Cells RC-5 is programmed
to change in three stages in accordance with the Starting
Temperature (.degree. C.), Average Ramp (.degree. C./minute) and
Duration (Minutes) as set forth in Table 5; and
[0015] FIG. 6 is a schematic depicting an offshore tie-in-platform
in fluidic communication with wellheads and with an onshore plant
via pipelines, where the tie-in-platform includes a receptacle for
holding clathrate hydrate inhibitors.
DETAILED DESCRIPTION
[0016] While the following terms are believed to be well understood
by one of ordinary skill in the art, definitions are set forth to
facilitate explanation of the present-disclosed subject matter.
[0017] The term "copolymer" refers to a polymer having two or more
different monomeric repeating units. For example, the copolymer may
include two different monomeric repeating units (that is, a
bipolymer). In one or more embodiments, the copolymers are random.
As will be appreciated by one of ordinary skill in the art, the
copolymers are random when the distribution of monomeric repeating
units follows statistical laws. For example, copolymers are random
when the probability of finding a given monomeric repeating unit at
a particular point in the polymer chain is equal to the mole
fraction of that monomeric repeating unit in the chain. Random
copolymers may also be referred to as statistical copolymers.
[0018] The term "monovalent" refers to a radical having an
unsatisfied valence of one, where a valence "-" is unsatisfied at
one end of the radical. For example, in embodiments where a
hydrocarbon group is present at one end of an aliphatic radical or
a heteroaliphatic radical, the aliphatic radical or the
heteroaliphatic radical is monovalent when one hydrogen atom has
been removed from the hydrocarbon group present at one end of the
aliphatic radical or the heteroaliphatic radical. As another
example, in embodiments where a heteroatom is present at one end of
the heteroaliphatic radical, the heteroaliphatic radical is
monovalent when the heteroatom present at one end of the
heteroaliphatic radical has an unsatisfied valence "-".
[0019] The term "divalent" refers to a radical having an
unsatisfied valence of two, where a valence "-" is unsatisfied at
two ends of the radical. For example, in embodiments where a
hydrocarbon group is present at two ends of an aliphatic radical or
a heteroaliphatic radical, the aliphatic radical or the
heteroaliphatic radical is divalent when one hydrogen atom has been
removed from each of the hydrocarbon groups present at two ends of
the aliphatic radical or the heteroaliphatic radical. As another
example, in embodiments where a heteroatom is present at two ends
of the heteroaliphatic radical, the heteroaliphatic radical is
divalent when each of the heteroatoms present at two ends of the
heteroaliphatic radical has an unsatisfied valence "-". Similarly,
as another example, in embodiments where a hydrocarbon group is
present at one end of a heteroaliphatic radical and a heteroatom is
present at one end of the heteroaliphatic radical, the
heteroaliphatic radical is divalent when one hydrogen atom has been
removed from the hydrocarbon group present at one end of the
heteroaliphatic radical and when the heteroatom present at one end
of the heteroaliphatic radical has an unsatisfied valence "-".
[0020] The term "aliphatic" refers to saturated straight chain
(that is, linear or unbranched) and branched hydrocarbon radicals.
In embodiments, the aliphatic hydrocarbon radicals are monovalent
or divalent. As will be appreciated by one of ordinary skill in the
art, aliphatic is intended to include, but is not limited to, alkyl
moieties. Thus, the term "alkyl" includes straight and branched
alkyl groups. In certain embodiments, the term "lower alkyl" may be
used to indicate alkyl groups (branched or unbranched) having from
1 to 6 carbon atoms.
[0021] In embodiments, the alkyl groups described contain from 1 to
7 aliphatic carbon atoms. In other embodiments, the alkyl groups
described contain from 1 to 6 aliphatic carbon atoms. In still
other embodiments, the alkyl groups described contain from 1 to 4
aliphatic carbon atoms. Illustrative aliphatic groups thus include,
but are not limited to, for example, methyl, ethyl, n-propyl,
isopropyl, allyl, n-butyl, sec-butyl, isobutyl, tert-butyl,
n-pentyl, sec-pentyl, isopentyl, tert-pentyl, n-hexyl, sec-hexyl,
moieties and the like.
[0022] The term "heteroaliphatic" refers to aliphatic radicals in
which one or more carbon atoms in the main chain have been
substituted with a heteroatom. By way of example, an aliphatic
radical having four main chain atoms where one carbon atom has been
substituted with one heteroatom is referred to as a C.sub.4
heteroaliphatic. As another example, an aliphatic radical having
seven main chain atoms where two carbon atoms have been substituted
with two heteroatoms is referred to as a C.sub.7 heteroaliphatic.
In embodiments, the heteroaliphatic radicals are monovalent or
divalent. Thus, heteroaliphatic is intended to include aliphatic
chains which contain one or more oxygen, sulfur, or nitrogen atoms,
for example, in place of carbon atoms. Heteroaliphatic moieties may
be linear or branched.
[0023] The term "heterocycloalkyl," "heterocycle," or
"heterocyclic" refers to radicals that combine the properties of
heteroaliphatic and cyclic moieties and include, but are not
limited to, saturated mono- or polycyclic ring systems having from
5 to 8 atoms, where at least one ring atom is a N heteroatom; and
where zero, one or two ring atoms are additional heteroatoms
independently chosen from S, O, and N (where the nitrogen and
sulfur heteroatoms may optionally be oxidized). In certain
embodiments, the terms heterocycloalkyl, heterocycle or
heterocyclic refer to non-aromatic 5-membered, 6-membered, or
7-membered rings or polycyclic moieties where at least one ring
atom is a N heteroatom, and where zero, one or two ring atoms are
additional heteroatoms independently chosen from S, O, and N (where
the nitrogen and sulfur heteroatoms may optionally be oxidized and
the nitrogen atom may be quarternized) including, but not limited
to, bicyclic or tricyclic groups. Representative heterocycles
include, but are not limited to, heterocycles such as pyrrolidinyl,
pyrazolidinyl, imidazolidinyl, piperidinyl, piperazinyl,
oxazolidinyl, isoxazolidinyl, morpholinyl, thiazolidinyl,
isothiazolidinyl, dithiazolyl, dithiazolidinyl, and azepanyl. In
embodiments, the heterocycloalkyls, heterocycles or heterocyclics
are saturated mono- or polycyclic moieties having from 5 to 8 ring
atoms of which one ring atom is N; and of which zero, one or two
ring atoms are additional heteroatoms independently chosen from S,
O, and N; and the remaining ring atoms are carbon, the radicals
being joined to the rest of the molecule via a N ring atom, such
as, for example, pyrollidinyl, pyrazolidinyl, imidazolidinyl,
piperidinyl, piperazinyl, morpholinyl, thiazolidinyl, and
azepanyl.
[0024] The term "clathrate hydrates" refers to crystalline
water-based solids in which host water molecules enclathrate gas
guest molecules. In one or more embodiments, crystalline
water-based solids in which host water molecules are hydrogen
bonded around the gas guest molecules such that the gas guest
molecules are trapped inside cages of hydrogen bonded host water
molecules. The clathrate hydrates may include a structure (Type) I
(that is, SI), a structure (Type) II (that is, SII), or a structure
(Type) H (that is, SH) crystalline structure.
[0025] The terms "inhibit", "inhibition", and "inhibiting" refer to
any improvement in controlling, delaying, reducing, mitigating,
preventing, or combinations thereof the formation, growth,
adherence, agglomeration, or combinations thereof of clathrate
hydrates in any manner. For example, clathrate hydrate inhibition
includes, but should not be limited to, thermodynamically modifying
the conditions at which clathrate hydrates form, kinetically
delaying clathrate hydrate nucleation, dissolving clathrate
hydrates, breaking up clathrate hydrates, or combinations thereof.
Further, clathrate hydrate inhibition may include the complete
cessation of clathrate hydrate formation, where clathrate hydrate
formation is entirely prevented.
[0026] The terms "formation", "forming", and "form" refer to any
process in which host water molecules enclathrate gas guest
molecules in a crystalline structure, in which clathrate hydrates
grow, in which clathrate hydrates adhere, in which clathrate
hydrates agglomerate, or combinations thereof. The term
"enclathrate" refers to hydrogen bonding of host water molecules
around gas guest molecules.
[0027] The terms "subcooling temperature" and "T.sub.sc" refer to
the difference between an operating temperature of a field gas and
the three-phase equilibrium temperature of the clathrate hydrate of
the field gas at 70 bars. Thus, the term "first subcooling
temperature" refers to the difference between an operating
temperature of a field gas in a first operation stage and the
three-phase equilibrium temperature. In embodiments, the first
subcooling temperature is from about 0.degree. C. to about
4.0.degree. C., or from about 0.degree. C. to about 1.0.degree. C.,
or from about 1.0.degree. C. to about 2.0.degree. C., or from about
2.0.degree. C. to about 3.5.degree. C., or about 4.0.degree. C.
Similarly, the term "second subcooling temperature" refers to the
difference between an operating temperature of a field gas in a
second operation stage and the three-phase equilibrium temperature.
In embodiments, the second subcooling temperature is from about
4.0.degree. C. to about 10.0.degree. C., or from about 4.0.degree.
C. to about 4.6.degree. C., or from about 4.6.degree. C. to about
5.6.degree. C., or from about 5.6.degree. C. to about 7.0.degree.
C., or from about 7.0.degree. C. to about 8.0.degree. C., or about
5.6.degree. C. Additionally, the term "third subcooling
temperature" refers to the difference between an operating
temperature of a field gas in a third operation stage and the
three-phase equilibrium temperature. In embodiments, the third
subcooling temperature is from about 5.6.degree. C. to about
15.0.degree. C., or from about 5.6.degree. C. to about 7.0.degree.
C., or from about 7.0.degree. C. to about 8.6.degree. C., or from
about 8.6.degree. C. to about 10.5.degree. C., or from about
10.5.degree. C. to about 12.0.degree. C., or from about
12.0.degree. C. to about 15.0.degree. C., or about 10.5.degree.
C.
[0028] Embodiments of the present disclosure are directed toward
succinimide-based copolymers (that is, SBC) having General Formula
(I), to methods for synthesizing succinimide-based copolymers
having General Formula (I), and to methods for inhibiting formation
of clathrate hydrates using succinimide-based copolymers having
General Formula (I). Embodiments of the succinimide-based
copolymers having General Formula (I) will now be described in
detail. Thereafter, embodiments of methods for synthesizing
copolymers of General Formula (I) will be described. Then, methods
for inhibiting formation of clathrate hydrates using
succinimide-based copolymers having General Formula (I) will be
described with reference to FIG. 6.
I. Succinimide-Based Copolymers of General Formula (I)
[0029] In one or more embodiments, the disclosure describes
succinimide-based copolymers having General Formula (I):
##STR00004##
[0030] In the copolymers of General Formula (I), R.sup.1 is chosen
from divalent C.sub.4-C.sub.7 aliphatic groups and divalent
C.sub.4-C.sub.7 heteroaliphatic groups, optionally substituted with
one or more C.sub.1-C.sub.6 aliphatic groups, heteroatoms
independently chosen from O, N, and S, or combinations thereof;
where the divalent C.sub.4-C.sub.7 heteroaliphatic groups include
one or two heteroatoms independently chosen from O, N, and S, and
where the maximum number of heteroatoms in R.sup.1 is two; x is a
molar fraction range chosen from about 0.05 to about 0.95; and y is
a molar fraction range chosen from about 0.05 to about 0.95, where
the summation of x and y equals 1.
[0031] In the copolymers of General Formula (I), R.sup.1 is chosen
from divalent C.sub.4-C.sub.7 aliphatic groups and divalent
C.sub.4-C.sub.7 heteroaliphatic groups. In embodiments, R.sup.1 is
chosen from divalent C.sub.4-C.sub.7 linear aliphatic groups,
divalent C.sub.4-C.sub.7 branched aliphatic groups, divalent
C.sub.4-C.sub.7 linear heteroaliphatic groups, and divalent
C.sub.4-C.sub.7 branched heteroaliphatic groups. In embodiments,
R.sup.1 is chosen from divalent C.sub.4-C.sub.6 linear aliphatic
groups and divalent C.sub.4-C.sub.6 linear heteroaliphatic groups.
In other embodiments, R.sup.1 is chosen from C.sub.4-C.sub.6 linear
aliphatic groups. In illustrative, non-limiting embodiments,
R.sup.1 is chosen from --(CH.sub.2).sub.4--, --(CH.sub.2).sub.5--,
and --(CH.sub.2).sub.6--.
[0032] In one or more embodiments, R.sup.1 is optionally
substituted with one or more substituting groups. In embodiments
where R.sup.1 is substituted with one or more substituting groups,
R.sup.1 may include from 1 to 8, or from 2 to 6, or from 3 to 5
substituting groups. In embodiments where R.sup.1 is chosen from
divalent C.sub.4-C.sub.7 aliphatic groups and divalent
C.sub.4-C.sub.7 heteroaliphatic groups and is substituted with one
or more substituting groups, the divalent C.sub.4-C.sub.7 aliphatic
groups and the divalent C.sub.4-C.sub.7 heteroaliphatic groups
include additional unsatisfied valences "-" within the divalent
C.sub.4-C.sub.7 aliphatic groups and the divalent C.sub.4-C.sub.7
heteroaliphatic groups to accommodate bonding with the substituting
groups. For example, in embodiments where R.sup.1 is chosen from
divalent C.sub.4-C.sub.7 aliphatic groups and divalent
C.sub.4-C.sub.7 heteroaliphatic groups and is substituted,
additional hydrogen atoms may have been removed from the
hydrocarbon groups present within the divalent C.sub.4-C.sub.7
aliphatic groups and the divalent C.sub.4-C.sub.7 heteroaliphatic
groups to accommodate bonding with the substituting groups.
[0033] In embodiments, R.sup.1 is optionally substituted with one
or more C.sub.1-C.sub.6 aliphatic groups, heteroatoms independently
chosen from O, N, and S, or combinations thereof. In embodiments,
R.sup.1 is optionally substituted with one or more C.sub.1-C.sub.6
linear aliphatic groups, C.sub.1-C.sub.6 branched aliphatic groups,
heteroatoms independently chosen from O, N, and S, or combinations
thereof. In embodiments, R.sup.1 is substituted with one or more
C.sub.1-C.sub.6 linear aliphatic groups, C.sub.1-C.sub.6 branched
aliphatic groups, or combinations thereof. In illustrative,
non-limiting embodiments, R.sup.1 is substituted with one or more
lower alkyls. In other illustrative, non-limiting embodiments,
R.sup.1 is substituted with one or more C.sub.1-C.sub.4 linear
aliphatic groups, C.sub.1-C.sub.4 branched aliphatic groups, or
combinations thereof. In still other illustrative, non-limiting
embodiments, R.sup.1 is substituted with one or more
C.sub.2-C.sub.3 linear aliphatic groups, C.sub.2-C.sub.3 branched
aliphatic groups, or combinations thereof. In yet still other
illustrative, non-limiting embodiments, R.sup.1 is substituted with
one or more C.sub.1-C.sub.3 linear aliphatic groups,
C.sub.1-C.sub.3 branched aliphatic groups, or combinations thereof.
In still other illustrative, non-limiting embodiments, R.sup.1 is
substituted with one or more substituting groups independently
chosen from methyl, ethyl, n-propyl, isopropyl, allyl, n-butyl,
sec-butyl, isobutyl, tert-butyl, n-pentyl, sec-pentyl, isopentyl,
tert-pentyl, n-hexyl, sec-hexyl, moieties, or combinations
thereof.
[0034] In other embodiments, R.sup.1 is substituted with one or
more heteroatoms independently chosen from O, N, and S. In
embodiments where R.sup.1 is substituted with one or more
heteroatoms independently chosen from O, N, and S, the heteroatoms
may form a single bond or a double bond with R.sup.1. In
illustrative, non-limiting embodiments, R.sup.1 is substituted with
one heteroatom chosen from O, N, and S. In other illustrative,
non-limiting embodiments, R.sup.1 is substituted with one
heteroatom, where the one heteroatom is O.
[0035] In embodiments where R.sup.1 is chosen from divalent
C.sub.4-C.sub.7 aliphatic groups and divalent C.sub.4-C.sub.7
heteroaliphatic groups, the C.sub.4-C.sub.7 aliphatic groups and
the C.sub.4-C.sub.7 heteroaliphatic groups include an unsatisfied
valence "-" at two ends. In this way, R.sup.1 forms a
heterocycloalkyl or a heterocycle when bonded with the --N-- in the
rest of the copolymer molecule via its two unsatisfied end
valences. In embodiments, the heterocycloalkyl or heterocycle
formed when R.sup.1 is bonded with the --N-- in the rest of the
copolymer is non-aromatic. In illustrative, non-limiting
embodiments, the heterocycloalkyl or heterocycle formed is chosen
from pyrollidinyl, pyrazolidinyl, imidazolidinyl, piperidinyl,
piperazinyl, morpholinyl, thiazolidinyl, and azepanyl. In further
illustrative, non-limiting embodiments, the heterocycloalkyl, or
heterocycle formed is chosen from pyrrolidinyl, piperidinyl, and
azepanyl.
[0036] In embodiments, the heterocycloalkyl or heterocycle formed
has the following structure:
##STR00005##
where the heterocycloalkyl or heterocycle is attached to the rest
of the copolymer molecule via *. In embodiments, the
##STR00006##
is substituted. In illustrative, non-limiting embodiments, the
##STR00007##
is chosen from
##STR00008##
In other illustrative, non-limiting embodiments, the
##STR00009##
is chosen from
##STR00010##
[0037] In the copolymers of General Formula (I), x is a molar
fraction range chosen from about 0.05 to about 0.95. In
embodiments, x is a molar fraction range chosen from about 0.1 to
about 0.9, or from about 0.3 to about 0.7, or a molar fraction of
about 0.5. In illustrative, non-limiting embodiments, x is a molar
fraction range of from about 0.15 to about 0.85. In yet other
illustrative, non-limiting embodiments, x is a molar fraction of
greater than 0.
[0038] In the copolymers of General Formula (I), y is a molar
fraction range chosen from about 0.05 to about 0.95. In
embodiments, y is a molar fraction range chosen from about 0.1 to
about 0.9, or from about 0.3 to about 0.7, or a molar fraction of
about 0.5. In illustrative, non-limiting embodiments, y is a molar
fraction range of from about 0.15 to about 0.85. In yet other
illustrative, non-limiting embodiments, y is a molar fraction of
greater than 0.
[0039] In the copolymers of General Formula (I), the summation of x
and y equals 1. In one or more embodiments, x is a molar fraction
of greater than 0 and y is a molar fraction of greater than 0. In
embodiments, x and y are equimolar fractions.
[0040] In embodiments, the viscosity average molecular weight of
the copolymers of General Formula (I) is from about 1,000
grams/mole (that is g/mol), to about 20,000 g/mol, or from about
1,500 g/mol to about 15,000 g/mol, or from about 5,000 g/mol to
about 10,000 g/mol, or about 8,000 g/mol. In illustrative,
non-limiting embodiments, the viscosity average molecular weight of
the copolymers of General Formula (I) is from about 5,000 g/mol to
about 15,000 g/mol. In embodiments, the viscosity average molecular
weight of the copolymers was determined via gel permeation
chromatography (that is, GPC), employing 0.7% trimethylamine in
tetrahydrofuran (that is, THF) as a mobile phase, Phenogel.TM.
(Phenomenex, Sutter Creek, Calif.) as stationary phases (of
differing pore sizes, 500 .ANG., 100 .ANG., and 50 .ANG.) in three
columns in series, with a refractive index detector (that is, RID).
Calibration was performed using polystyrene standards. Moreover,
the viscosity average molecular weight of the copolymers of General
Formula (I) as determined by GPC was confirmed via sulfur elemental
analysis.
[0041] In illustrative, non-limiting embodiments, R.sup.1 is chosen
from divalent C.sub.4-C.sub.6 linear aliphatic groups and divalent
C.sub.4-C.sub.6 linear heteroaliphatic groups; x is a molar
fraction range chosen from about 0.15 to about 0.85; and y is a
molar fraction range chosen from about 0.15 to about 0.85. In other
illustrative, non-limiting embodiments, R.sup.1 is chosen from
divalent C.sub.4-C.sub.6 linear aliphatic groups; x is a molar
fraction range chosen from about 0.15 to about 0.85; and y is a
molar fraction range chosen from about 0.15 to about 0.85. In still
other illustrative, non-limiting embodiments, R.sup.1 is chosen
from divalent C.sub.4-C.sub.6 linear aliphatic groups; x is a molar
fraction range chosen from about 0.3 to about 0.7; and y is a molar
fraction range chosen from about 0.3 to about 0.7.
[0042] In illustrative, non-limiting embodiments,
##STR00011##
is chosen from
##STR00012##
x is a molar fraction range of from about 0.3 to about 0.7; and y
is a molar fraction range of from about 0.3 to about 0.7. In other
illustrative, non-limiting embodiments,
##STR00013##
is chosen from
##STR00014##
x is a molar fraction of about 0.5; and y is a molar fraction of
about 0.5. In still other illustrative, non-limiting
embodiments,
##STR00015##
is chosen from
##STR00016##
and x and y are equimolar fractions. In yet still other
illustrative, non-limiting embodiments,
##STR00017##
is chosen from
##STR00018##
x is a molar fraction of about 0.5; and y is a molar fraction of
about 0.5.
[0043] In other illustrative, non-limiting embodiments, x is a
molar fraction range of from about 0.15 to about 0.85; and y is a
molar fraction range of from about 0.15 to about 0.85. In still
other illustrative, non-limiting embodiments, x is a molar fraction
range of from about 0.3 to about 0.7; and y is a molar fraction
range of from about 0.3 to about 0.7. In yet still other
illustrative, non-limiting embodiments, x is a molar fraction of
about 0.5; and y is a molar fraction of about 0.5.
[0044] In Table 1, copolymers having General Formula (I) according
to various embodiments are provided:
TABLE-US-00001 TABLE 1 Copolymers of General Formula (I) Reference
Copolymer of General Formula (I) Name SBC-1 ##STR00019##
Polypyrrolidinoaspartamide-Ran- Polysuccinimide SBC-2 ##STR00020##
Polypiperidinoaspartamide-Ran- Polysuccinimide SBC-3 ##STR00021##
Polyazapanoaspartamide-Ran- Polysuccinimide
[0045] In embodiments, the at least one copolymer of General
Formula (I) is water soluble. In further embodiments, the at least
one copolymer of General Formula (I) is thermally stable. In
illustrative, non-limiting embodiments, the at least one copolymer
of General Formula (I) is thermally stable up to a temperature of
about 50.degree. C. In embodiments, the at least one copolymer of
General Formula (I) is in the form of a sodium salt.
[0046] Embodiments of succinimide-based copolymers having General
Formula (I) have been described in detail. Embodiments of methods
for synthesizing the copolymers of General Formula (I) will be
described.
II. Methods for Synthesizing the Copolymers of General Formula
(I)
[0047] In one or more embodiments, the disclosure describes methods
for synthesizing the copolymers of General Formula (I). However,
the copolymers of General Formula (I) may be synthesized via any
suitable synthetic scheme known to a person of ordinary skill in
the art. In illustrative, non-limiting embodiments, the copolymers
of General Formula (I) were synthesized in accordance with the
following reaction scheme:
##STR00022##
[0048] More specifically, succinimide-based copolymers having
General Formula (I) were synthesized by grinding L-aspartic acid
(about 66.5 grams or g, 0.5 moles or m) with a mortar and pestle
while adding concentrated H.sub.2SO.sub.4 (about 3.3 g) to the
L-aspartic acid dropwise to form a grinded mixture. The grinded
mixture was stirred in a round bottom flask using a magnetic
stir-bar and heated via an oil bath at about 203.degree. C. After
30 minutes, the grinded mixture was cooled to room temperature,
grinded thoroughly, and heated under stirring again at about
203.degree. C. for 7 hours. The grinded mixture was then cooled to
room temperature and filtered while washing with hot water (about
300 milliliters, that is mL, 55.degree. C.) and methanol (about 150
mL). The resultant polysuccinimide (that is, PSI), was dried under
vacuum at about 70.degree. C. to a constant weight (about 42 g,
87%).
[0049] After drying the PSI under vacuum at about 70.degree.
C.,
##STR00023##
(about 50 millimoles, that is mmol) (that is, a cyclic amine) was
added dropwise to the dried PSI (about 9.7 g, 100 mL) in DMF (about
40 mL) at about 0.degree. C. over a period of 5 minutes to form a
reaction mixture. The reaction mixture was stirred at room
temperature for 18 hours. The product of the reaction mixture was
precipitated in acetone, filtered, and dried under vacuum at about
60.degree. C. to a constant weight to obtain succinimide-based
copolymers of General Formula (I):
##STR00024##
[0050] The succinimide-based copolymers of General Formula (I) were
found to be soluble in water was well as methanol. In embodiments,
R.sup.1 of
##STR00025##
and x, and y of General Formula (I) are as described previously
with regard to General Formula (I). As will be appreciated by one
of ordinary skill in the art, quantities of reactants, for
example,
##STR00026##
in the grinded mixture or the reaction mixture may be adjusted. For
example, quantities of reactants may be adjusted to achieve varying
molar fractions x and y of each monomeric repeating unit.
[0051] Embodiments of methods for synthesizing the copolymers of
General Formula (I) have now been described in detail. Embodiments
of methods for inhibiting formation of clathrate hydrates will now
be described in detail with reference to FIG. 6.
III. Methods for Inhibiting Formation of Clathrate Hydrates
[0052] In one or more embodiments, the disclosure describes methods
for inhibiting clathrate hydrates in a fluid capable of forming the
clathrate hydrates, the methods including contacting the fluid with
at least one copolymer of General Formula (I) under conditions
suitable for forming the clathrate hydrates. In further
embodiments, the at least one copolymer of General Formula (I) is
as described previously.
[0053] In embodiments, in the at least one copolymer of General
Formula (I), R.sup.1 is chosen from divalent C.sub.4-C.sub.7
aliphatic groups and divalent C.sub.4-C.sub.7 heteroaliphatic
groups, optionally substituted with one or more C.sub.1-C.sub.6
aliphatic groups, heteroatoms independently chosen from O, N, and
S, or combinations thereof; where: the divalent C.sub.4-C.sub.7
heteroaliphatic groups include one or two heteroatoms independently
chosen from O, N, and S, and the maximum number of heteroatoms in
R.sup.1 is two; x is a molar fraction range chosen from 0.05 to
0.95; and y is a molar fraction range chosen from 0.05 to 0.95,
where the summation of x and y equals 1.
[0054] In illustrative, non-limiting embodiments, in the at least
one copolymer of General Formula (I), R.sup.1 is chosen from
divalent C.sub.4-C.sub.6 linear aliphatic groups and divalent
C.sub.4-C.sub.6 linear heteroaliphatic groups; x is a molar
fraction range of from about 0.15 to about 0.85; and y is a molar
fraction range of from about 0.15 to about 0.85. In other
illustrative, non-limiting embodiments, R.sup.1 is chosen from
divalent C.sub.4-C.sub.6 linear aliphatic groups; x is a molar
fraction range chosen from about 0.3 to about 0.7; and y is a molar
fraction range chosen from about 0.3 to about 0.7. In still other
illustrative, non-limiting embodiments,
##STR00027##
is chosen from
##STR00028##
x is a molar fraction of about 0.5; and y is a molar fraction of
about 0.5. In yet still other illustrative, non-limiting
embodiments,
##STR00029##
is chosen from
##STR00030##
x is a molar fraction of about 0.5; and y is a molar fraction of
about 0.5. In other illustrative, non-limiting embodiments, in the
at least one copolymer of General Formula (I), the viscosity
average molecular weight of the copolymer is from about 1,000 g/mol
to about 20,000 g/mol.
[0055] In embodiments, the fluid is contacted with a formulation
including the at least one copolymer of General Formula (I). More
specifically, in embodiments, the formulation includes one or more
of the at least one copolymer of General Formula (I) (for example,
two or more copolymers of General Formula (I) could be used),
solvents, or additives. In embodiments, the at least one copolymer
of General Formula (I) is compatible with additives. In
embodiments, the additives are chosen from corrosion inhibitors and
synergists. In illustrative, non-limiting embodiments, the
formulation includes from about 0.01% to about 15% of the at least
one copolymer of General Formula (I), from about 0% to about 20% of
the solvent, and from about 0% to about 1% of the additive. In
other illustrative, non-limiting embodiments, the formulation
includes from about 0.1% to about 5% of the at least one copolymer
of General Formula (I), from about 0% to about 10% of the solvent,
from 0% to about 10% of the additives, from 0 parts per million
(that is, ppm; a mass fraction) to about 3000 ppm of the corrosion
inhibitors, from 0 ppm to about 3000 ppm of the scale inhibitors,
from 0% to about 40% of the thermodynamic hydrate inhibitors, and
from about 0.1% to about 10% of the anti-agglomerates. In
embodiments, the amounts disclosed of the formulation relate to the
percentage or ppm of the water cut.
[0056] In illustrative, non-limiting embodiments, the solvents are
chosen from water, alcohols, for example, monoethylene glycol,
methanol, ethanol, and isobutanol, ketones, ethers, and non-polar
aromatics, for example, toluene and benzene. In further
illustrative, non-limiting embodiments, the solvents are alcohols
chosen from glycols, for example, monoethylene glycol. In other
illustrative, non-limiting embodiments, the additives are chosen
from corrosion inhibitors and synergists. In illustrative,
non-limiting embodiments, the corrosion inhibitors include gas
corrosion inhibitors. In embodiments, the synergists are chosen
from scale inhibitors, thermodynamic hydrate inhibitors, low dose
hydrate inhibitors, and anti-agglomerates. In illustrative,
non-limiting embodiments, the thermodynamic hydrate inhibitors are
chosen from glycol ethers and methanol. In illustrative,
non-limiting embodiments, low dose hydrate inhibitors are chosen
from Poly(N-vinylcaprolactam) and
poly(N-methyl-N-vinylacetamide).
[0057] In embodiments, the fluid is contacted with at least one
copolymer of General Formula (I) under conditions suitable for
forming clathrate hydrates. In embodiments, the fluid is contacted
with about 3 weight % of the formulation, where the amount of
formulation relates to the percentage of the water cut. In
embodiments, the at least one copolymer of General Formula (I) is
contacted with the fluid via methods known to one of ordinary skill
in the art. For example, the at least one copolymer of General
Formula (I) may be contacted with the fluid via adding, combining,
mixing, injecting, or combinations thereof. In illustrative,
non-limiting embodiments, conditions suitable for forming clathrate
hydrates include conditions where the pressure on the fluid is from
about 11 bara to about 200 bara, or from about 11 bara to about 50
bara, or from about 50 bara to about 70 bara, or from about 70 bara
to about 100 bara, or from about 100 bara to about 140 bara, or
from about 140 bara to about 150 bara, or from about 150 bara to
about 200 bara, and also includes conditions where the temperature
of the fluid is from about 0.degree. C. to about 25.degree. C., or
from about 0.degree. C. to about 10.degree. C., or from about
10.degree. C. to about 12.degree. C., or from about 12.degree. C.
to about 16.degree. C., or from about 16.degree. C. to about
19.degree. C., or from about 19.degree. C. to about 20.degree. C.,
or from about 20.degree. C. to about 25.degree. C. In illustrative,
non-limiting embodiments, conditions suitable for forming clathrate
hydrates include conditions where the temperature of the fluid is
equal to or less than the three-phase equilibrium temperature.
[0058] In other embodiments, contacting the fluid with at least one
copolymer of General Formula (I) under conditions suitable for
forming the clathrate hydrates is effective to inhibit or inhibits
the formation of the clathrate hydrates at a first subcooling
temperature. In other embodiments, contacting the fluid with at
least one copolymer of General Formula (I) under conditions
suitable for forming the clathrate hydrates is effective to inhibit
or inhibits the formation of the clathrate hydrates at a second
subcooling temperature. In still other embodiments, contacting the
fluid with at least one copolymer of General Formula (I) under
conditions suitable for forming the clathrate hydrates is effective
to inhibit or inhibits the formation of the clathrate hydrates at a
third subcooling temperature.
[0059] In illustrative, non-limiting embodiments, contacting the
fluid with at least one copolymer of General Formula (I) under
conditions suitable for forming the clathrate hydrates is effective
to inhibit or inhibits the formation of the clathrate hydrates in a
pressure range of from about 40 bars to about 200 bars. In other
illustrative, non-limiting embodiments, contacting the fluid with
at least one copolymer of General Formula (I) under conditions
suitable for forming the clathrate hydrates is effective to inhibit
or inhibits the formation of the clathrate hydrates in a pressure
range of from about 70 bars to about 100 bars.
[0060] In embodiments, the fluid capable of forming clathrate
hydrates includes water host molecules and natural gas guest
molecules. In further embodiments, the natural gas guest molecules
are chosen from methane, ethane, propane, butane, pentane, carbon
dioxide, hydrogen sulfide, nitrogen, or combinations thereof. In
illustrative, non-limiting embodiments, the fluid capable of
forming clathrate hydrates includes natural gas guest molecules in
the following compositional amounts: methane (from about 60-90 mole
%); ethane (from about 0-4 mole %); propane (from about 0-1 mole
%); butane (from about 0-1 mole %); carbon dioxide (from about 5-15
mole %); hydrogen sulfide (from about 0-5 mole %); and nitrogen
(from about 5-15 mole %). In other embodiments, the fluid capable
of forming clathrate hydrates includes brine, such as is described
subsequently in Table 2. In illustrative, non-limiting embodiments,
the brine includes chloride anions, sodium cations, acetic acid,
formic acid, a conjugate base of acetic acid, a conjugate base of
formic acid, or combinations thereof.
[0061] In illustrative, non-limiting embodiments, the fluid capable
of forming clathrate hydrates includes acid gas guest molecules.
For example, in embodiments, the fluid capable of forming clathrate
hydrates includes carbon dioxide and hydrogen sulfide. In
illustrative, non-limiting embodiments, the fluid capable of
forming clathrate hydrates is rich in carbon dioxide, hydrogen
sulfide, or a combination of carbon dioxide and hydrogen sulfide.
For example, the fluid capable of forming clathrate hydrates may be
rich in hydrogen sulfide where it includes at least about 2 mole %
of hydrogen sulfide. As another example, the fluid capable of
forming clathrate hydrates may be rich in carbon dioxide where it
includes at least about 8 mole % of carbon dioxide. As yet another
example, the fluid capable of forming clathrate hydrates may be
rich in both carbon dioxide and hydrogen sulfide where it includes
at least about 8 mole % of carbon dioxide and at least about 2 mole
% of hydrogen sulfide. In still other illustrative, non-limiting
embodiments, the fluid capable of forming clathrate hydrates
includes carbon dioxide, hydrogen sulfide, nitrogen, or
combinations thereof. In yet other illustrative, non-limiting
embodiments, the fluid capable of forming clathrate hydrates
includes methane, ethane, propane, butane, carbon dioxide, hydrogen
sulfide, and nitrogen gas guest molecules. In yet still other
illustrative, non-limiting embodiments, the fluid capable of
forming clathrate hydrates does not include hydrogen sulfide,
carbon dioxide, or a combination of hydrogen sulfide and carbon
dioxide.
[0062] In embodiments, the fluid capable of forming clathrate
hydrates is capable of forming SI clathrate hydrates, SII clathrate
hydrates, SH clathrate hydrates, or combinations thereof. In
embodiments, fluids capable of forming SI clathrate hydrates
include at least one of methane, ethane, propane, butane, carbon
dioxide, or hydrogen sulfide. In embodiments, fluids capable of
forming SII clathrate hydrates include at least one of propane,
butane, or pentane. In embodiments, SI clathrate hydrates and SII
clathrate hydrates have crystalline cubic structures which are well
known to one of ordinary skill in the art. In embodiments, SH
clathrate hydrates have hexagonal structures which are well known
to one of ordinary skill in the art. In further embodiments where
the fluid capable of forming clathrate hydrates is capable of
forming SI clathrate hydrates, SII clathrate hydrates, SH clathrate
hydrates, or combinations thereof, the contacting is effective to
inhibit or inhibits formation of SI clathrate hydrates, SII
clathrate hydrates, SH clathrate hydrates, or combinations
thereof.
[0063] In embodiments, the fluid is contacted with the at least one
copolymer of General Formula (I) in an amount effective to inhibit
clathrate hydrate formation. In specific embodiments, the fluid is
contacted with from about 0.01 weight % to about 5 weight %, or
from about 0.1 weight % to about 4 weight %, or from about 0.5
weight % to about 4 weight %, or about 2.5 weight % of the at least
one copolymer of General Formula I. In embodiments, the weight % of
the at least one copolymer of General Formula I refers to the
weight % of the water cut. In embodiments, the at least one
copolymer of General Formula (I) is water soluble.
[0064] As shown in FIG. 6, in embodiments, the fluid capable of
forming the clathrate hydrates is contacted with the at least one
copolymer of General Formula (I) at a tie-in-platform 10. As shown
in FIG. 6, in embodiments, the tie-in-platform 10 is an offshore
platform which is in fluidic communication with an onshore plant
100 via a pipeline 50. In embodiments, the tie-in-platform 10 is in
fluidic communication with wellheads 200, 300, 400, 500, and 600,
which provide an interface for drilling and production equipment.
In embodiments, the fluid capable of forming the clathrate hydrates
is flowing in a pipeline 50. In further embodiments, the fluid
capable of forming the clathrate hydrates is flowing in pipeline 50
from an offshore site to an onshore site. In illustrative,
non-limiting embodiments, the fluid capable of forming the
clathrate hydrates is flowing in pipeline 50 from the
tie-in-platform 10 to the onshore plant 100. In illustrative,
non-limiting embodiments, the at least one copolymer of General
Formula (I) is injected into the fluid capable of forming the
clathrate hydrates at the tie-in-platform 10.
[0065] In embodiments, the tie-in-platform 10 includes a receptacle
15 for holding clathrate hydrate inhibitors and a clathrate hydrate
inhibitor injection skid 20. In illustrative, non-limiting
embodiments, the at least one copolymer of General Formula (I) is
held in the receptacle 15 for holding clathrate hydrate inhibitors.
In illustrative, non-limiting embodiments, the at least one
copolymer of General Formula (I) is injected into the fluid capable
of forming the clathrate hydrates via the clathrate hydrate
inhibitor injection skid 20.
[0066] Embodiments of methods for inhibiting formation of clathrate
hydrates using the succinimide-based copolymers having General
Formula (I) have been described in detail.
EXAMPLES
[0067] The following non-limiting examples illustrate the synthesis
of the copolymers having General Formula (I), and also illustrate
methods of the present disclosure. The compounds synthesized should
be understood to be illustrative in nature and in no regard
limiting to the scope of General Formula (I) or of the methods
described.
Example 1: Synthesis of Succinimide-Based Copolymers Having General
Formula (I)
[0068] Materials and Methods.
[0069] Succinimide-based copolymers having General Formula (I) in
which R.sup.1 is --(CH.sub.2).sub.4--, x is 0.5, and y is 0.5, were
synthesized in accordance with the following reaction scheme:
##STR00031##
[0070] More specifically, succinimide-based copolymers having
General Formula (I) were synthesized by grinding L-aspartic acid
(about 66.5 g, 0.5 mol) with a mortar and pestle while adding
concentrated H.sub.2SO.sub.4 (about 3.3 g) to the L-aspartic acid
dropwise to form a grinded mixture. The grinded mixture was stirred
in a round bottom flask using a magnetic stir-bar and heated via an
oil bath at about 203.degree. C. After 30 minutes, the grinded
mixture was cooled to room temperature, grinded thoroughly, and
heated under stirring again at about 203.degree. C. using a
silicone oil bath for 7 hours. The grinded mixture was then cooled
to room temperature and filtered while washing with hot water
(about 300 mL, 55.degree. C.) and methanol (about 150 mL). The
resultant polysuccinimide (that is, PSI), was dried under vacuum at
about 70.degree. C. to a constant weight (about 42 g, 90%
yield).
[0071] A solution of about 0.5% PSI in dimethyl formamide (that is,
DMF), had a reduced viscosity (that is, .eta..sub.red) of about
8.57 mL/g as determined at about 25.degree. C. using an Ubbelohde
viscometer (viscometer constant K=0.005 mm.sup.2 s.sup.-2, SI
Analytics, College Station, Tex., USA). The viscosity average
molecular weight was estimated to be 9744 g/mol and the degree of
polymerization (that is, n) was estimated to be 100. The degree of
polymerization was calculated with the following empirical equation
(1):
n=3.52.times..eta..sub.red.sup.1.56 (1)
where n is the degree of polymerization and .eta..sub.red is the
reduced viscosity of a solution of 0.5% PSI in DMF expressed in
units of mL/g.
[0072] After drying the PSI under vacuum at about 70.degree. C.,
pyrollidine (50 mmol) was added dropwise to the dried PSI (about
9.7 g, 100 mL) in DMF (about 40 mL) at about 0.degree. C. over a
period of 5 minutes to form a reaction mixture. The reaction
mixture was stirred at room temperature for 18 hours. The product
of the reaction mixture was precipitated in acetone, filtered, and
dried under vacuum at about 60.degree. C. to a constant weight to
obtain a succinimide-based copolymer of structure (SBC-1):
##STR00032##
(Yield: about 90%). The succinimide-based copolymer of structure
(SBC-1) was found to be soluble in water was well as methanol.
[0073] Results.
[0074] As determined via .sup.1H NMR spectroscopy in D.sub.2O and
elemental analysis, the succinimide-based copolymer of structure
(SBC-1) was found to include the intact succinimide ring and the
opened ring in an approximate ratio of 1:1. For example,
referencing FIG. 1, for an approximate ratio of 1:1 of the intact
succinimide ring monomeric repeating unit and the opened ring
monomeric repeating unit, the area under .delta.1.6-2.0 ppm would
belong to the 4 hydrogen atoms marked f and would have an
integrated area (A), the 2 hydrogen atoms marked d and the 4
hydrogen atoms marked e would have an integrated area (B) (where
B=[A/4]*6), the 2 hydrogen atoms marked b would have an integrated
area (C) which would be calculated as (D-[A/4]*6), where D
represents the total area belonging to the hydrogen atoms marked b,
d, and e under .delta.2.4-3.7 ppm, and where the mole ratio of the
intact succinimide ring monomeric repeating unit and the opened
ring monomeric repeating unit would be calculated as (C/2):(A/4)
based on the ratio of a single hydrogen atom of the intact
succinimide ring monomeric repeating unit and the opened ring
monomeric repeating unit. Thus, the approximate ratio was confirmed
to be 1.01:1.00. Additionally, the following elemental analysis was
revealed: C: 53.0%; H: 5.2%, N: 15.2% (where an approximate ratio
of 1:1 in the SBC-1 would require the following elemental analysis:
53.31%; H: 5.15%; N: 15.55%).
Example 2: Synthesis of Succinimide-Based Copolymers Having General
Formula (I)
[0075] Materials and Methods.
[0076] Succinimide-based copolymers having General Formula (I) in
which R.sup.1 is --(CH.sub.2).sub.5--, x is 0.5, and y is 0.5, were
synthesized in accordance with the following reaction scheme:
##STR00033##
[0077] More specifically, succinimide-based copolymers having
General Formula (I) were synthesized by grinding L-aspartic acid
(about 66.5 g, 0.5 mol) with a mortar and pestle while adding
concentrated H.sub.2SO.sub.4 (about 3.3 g) to the L-aspartic acid
dropwise to form a grinded mixture. The grinded mixture was stirred
in a round bottom flask using a magnetic stir-bar and heated via an
oil bath at about 203.degree. C. After 30 minutes, the grinded
mixture was cooled to room temperature, grinded thoroughly, and
heated under stirring again at about 203.degree. C. using a
silicone oil bath for 7 hours. The grinded mixture was then cooled
to room temperature and filtered while washing with hot water
(about 300 mL, 55.degree. C.) and methanol (about 150 mL). The
resultant PSI was dried under vacuum at about 70.degree. C. to a
constant weight (about 42 g, 90% yield).
[0078] A solution of about 0.5% PSI in DMF had a reduced viscosity
of 8.57 mL/g as determined at 25.degree. C. using an Ubbelohde
viscometer (viscometer constant K=0.005 mm.sup.2 s.sup.-2, SI
Analytics). The viscosity average molecular weight was estimated to
be 9744 g/mol and the degree of polymerization was estimated to be
100. The degree of polymerization was calculated with the empirical
equation (1), as in Example 1.
[0079] After drying the PSI under vacuum at about 70.degree. C.,
piperidine (50 mmol) was added dropwise to the dried PSI (about 9.7
g, 100 mL) in DMF (about 40 mL) at 0.degree. C. over a period of 5
minutes to form a reaction mixture. The reaction mixture was
stirred at room temperature for 18 hours. The product of the
reaction mixture was precipitated in acetone, filtered, and dried
under vacuum at about 60.degree. C. to a constant weight to obtain
a succinimide-based copolymer of structure (SBC-2):
##STR00034##
(Yield: about 90%). The succinimide-based copolymer of structure
(SBC-2) was found to be soluble in water was well as methanol.
[0080] Results.
[0081] As determined via .sup.1H NMR spectroscopy in D.sub.2O and
elemental analysis, the succinimide-based copolymer of structure
(SBC-2) was found to include the intact succinimide ring and the
opened ring in an approximate ratio of 1:1. For example,
referencing FIG. 2, for an approximate ratio of 1:1 of the intact
succinimide ring monomeric repeating unit and the opened ring
monomeric repeating unit, the area under .delta.1.6-1.8 ppm would
belong to the 6 hydrogen atoms marked f and g and would have an
integrated area (A), the 2 hydrogen atoms marked d and the 4
hydrogen atoms marked e would have an integrated area (B) (where
B=[A/4]*6), the 2 hydrogen atoms marked b should have an integrated
area equal to area A, where the 2 hydrogen atoms marked b should
have an integrated area of (B) which would then be calculated as
(B=C-A), where C represents the total area belonging to the
hydrogen atoms marked b, d, and e under .delta.2.3-3.6 ppm, and
where the mole ratio of the intact succinimide ring monomeric
repeating unit and the opened ring monomeric repeating unit is
calculated as (B/2):(A/6), based on the ratio of a single hydrogen
atom of the intact succinimide ring monomeric repeating unit and
opened ring monomeric repeating unit. Thus, the approximate ratio
was confirmed to be 0.98:1.00. Additionally, the following
elemental analysis was revealed: C: 54.0%; H: 5.5%, N: 14.6% (where
an approximate ratio of 1:1 in the SBC-2 would require the
following elemental analysis: C: 54.40%; H: 5.43%; N: 14.90%).
Example 3: Synthesis of Succinimide-Based Copolymers Having General
Formula (I)
[0082] Materials and Methods.
[0083] Succinimide-based copolymers having General Formula (I) in
which R.sup.1 is --(CH.sub.2).sub.6--, x is 0.5, and y is 0.5, were
synthesized in accordance with the following reaction scheme:
##STR00035##
[0084] More specifically, succinimide-based copolymers having
General Formula (I) were synthesized by grinding L-aspartic acid
(about 66.5 g, 0.5 mol) with a mortar and pestle while adding
concentrated H.sub.2SO.sub.4 (about 3.3 g) to the L-aspartic acid
dropwise to form a grinded mixture. The grinded mixture was stirred
in a round bottom flask using a magnetic stir-bar and heated via an
oil bath at about 203.degree. C. After 30 minutes, the grinded
mixture was cooled to room temperature, grinded thoroughly, and
heated under stirring again at about 203.degree. C. using a
silicone oil bath for 7 hours. The grinded mixture was then cooled
to room temperature and filtered while washing with hot water
(about 300 mL, 55.degree. C.) and methanol (about 150 mL). The
resultant PSI was dried under vacuum at 70.degree. C. to a constant
weight (about 42 g, 90% yield).
[0085] A solution of about 0.5% PSI in DMF had a reduced viscosity
of 8.57 mL/g as determined at 25.degree. C. using an Ubbelohde
viscometer (viscometer constant K=0.005 mm.sup.2 s.sup.-2, SI
Analytics). The viscosity average molecular weight was estimated to
be 9744 g/mol and the degree of polymerization was estimated to be
100. The degree of polymerization was calculated with the empirical
equation (1), as in Example 1.
[0086] After drying the PSI under vacuum at about 70.degree. C.,
azepane (about 50 mmol) was added dropwise to the dried PSI (about
9.7 g, 100 mL) in DMF (about 40 mL) at 0.degree. C. over a period
of 5 minutes to form a reaction mixture. The reaction mixture was
stirred at room temperature for 18 hours. The product of the
reaction mixture was precipitated in acetone, filtered, and dried
under vacuum at about 60.degree. C. to a constant weight to obtain
a succinimide-based copolymer of structure (SBC-3):
##STR00036##
(Yield: about 93%). The succinimide-based copolymer of structure
(SBC-3) was found to be soluble in water was well as methanol.
[0087] Results.
[0088] As determined via .sup.1H NMR spectroscopy in D.sub.2O and
elemental analysis, the succinimide-based copolymer of structure
(SBC-3) was found to include the intact succinimide ring and the
opened ring in an approximate ratio of 1:1. For example,
referencing FIG. 3, for an approximate ratio of 1:1 of the intact
succinimide ring monomeric repeating unit and the opened ring
monomeric repeating unit, the area under .delta.1.2-1.7 ppm would
belong to the 8 hydrogen atoms marked f and g and would have an
integrated area (A), the 2 hydrogen atoms marked d and the 4
hydrogen atoms marked e should have an integrated area (B) which
would be calculated as (B=[A/8]*6), the 2 hydrogen atoms marked b
would have an integrated area of (C) which would be calculated as
(C=[D-B]), where D represents the total area belonging to the
hydrogen atoms marked b, d, and e under .delta.2.3-3.5 ppm, and
where the mole ratio of the intact succinimide ring monomeric
repeating unit and the opened ring monomeric repeating unit is
calculated as (C/2):(A/8), based on the ratio of a single hydrogen
atom of the intact succinimide ring monomeric repeating unit and
opened ring monomeric repeating unit. Thus, the approximate ratio
was confirmed to be 1.06:1.00. Additionally, the following
elemental analysis was revealed: C: 55.0%; H: 5.6%, N: 14.1% (where
an approximate ratio of 1:1 in the SBC-3 would require the
following elemental analysis: C: 55.35%; H: 5.67%; N: 14.35%).
Example 4: Characterization of Polyacrylamide-Co-Acrylic Acid and
Poly-Ethyl-Oxazoline Inhibition of Clathrate Hydrate Formation
[0089] Materials and Methods.
[0090] Polyacrylamide-co-acrylic acid (that is, PAC-AA) sodium salt
with about 70% carboxyl high carbonyl and a molecular weight of
about 200,000 (Polysciences, Warrington, Pa., USA) and
poly-ethyl-oxazoline (PEOx) (Sigma-Aldrich Corp. St. Louis, Mo.,
USA; CAS Number: 25805-17-8) were obtained commercially. The
ability of PAC-AA and PEOx to inhibit clathrate hydrate formation
was characterized. More specifically, Rocking Cells (that is, RC-5)
were employed to characterize the ability of PAC-AA and PEOx to
inhibit clathrate hydrate formation. The RC-5 included five
Hastelloy cells (PSL Systemtechnik Gmbh, Osterode am Harz, Germany)
capable of operating under high pressure (that is, up to 200 bars)
and in sour gas conditions. The five Hastelloy cells of the RC-5
were immersed in a temperature controlled bath containing ethylene
glycol and water. During operation, the RC-5 was rocked to achieve
mixing of the reactant slurry. The volume of the Hastelloy cell
with a mixing ball was about 30 mL. The RC-5 enabled formation of
natural gas clathrate hydrates under simulated operating conditions
to test the effectiveness of the PAC-AA and PEOx. Data acquisition
was completed with WinRC software to measure the pressure and
temperature with time in each of the five Hastelloy cells.
[0091] In a typical run, each of the five Hastelloy cells was
charged with about 10 mL of a polymer formulation. Specifically,
the 10 mL polymer formulation included polymers, such as, PAC-AA,
PEOx, or succinimide-based copolymers, (about 3 weight %), a
solvent (about 0.195 grams, that is grams, monoethylene glycol,
that is MEG), and brine (about 97 weight %, 9.7 g), as set forth in
Table 2. Then, the five Hastelloy cells were charged with a natural
gas for one hour until equilibrium was reached, as described in
Table 3, that is, a natural gas was added to the five Hastelloy
cells, to a pressure of about 70 bars and 21.degree. C. The brine
included an aqueous solution of chloride anions, sodium cations,
acetic acid, formic acid, and conjugate bases as set forth in Table
2:
TABLE-US-00002 TABLE 2 Brine Ion/Molecular Formula Common Name
Concentration (mg/L) Cl.sup.- Chloride Anions 607 Na.sup.+ Sodium
Cations 393 CH.sub.3COOH Acetic Acid 500 HCOOH Formic Acid 250
[0092] Because natural gas in the field contains large amounts of
methane, carbon dioxide, hydrogen sulfide, and nitrogen and also
contains small amounts of ethane, propane, and butane, to simulate
pipeline operating conditions in the field, a natural gas
composition as set forth in Table 3 was employed:
TABLE-US-00003 TABLE 3 Natural Gas Composition Molecular Formula
Common Name Mole % CH.sub.4 Methane 79.6 C.sub.2H.sub.6 Ethane 1.4
C.sub.3H.sub.8 Propane 0.2 C.sub.4H.sub.10 Butane 0.1 CO.sub.2
Carbon Dioxide 9.2 H.sub.2S Hydrogen Sulfide 2.3 N.sub.2 Nitrogen
7.2
[0093] In this specific Example, each of the five Hastelloy cells
were charged with 10 mL of a polymer formulation including PAC-AA
or PEOx (about 3 weight %) and the brine (about 97 weight %) of
Table 2. PAC-AA and PEOx were tested separately, that is, two
different polymers were not paired together in a single test. Then,
the five Hastelloy cells were charged with a natural gas, as
described in Table 3, to a pressure of about 70 bars at 21.degree.
C. Referencing FIG. 4, the RC-5 was then programmed to change
temperature at three operation stages as set forth generally in
Table 4:
TABLE-US-00004 TABLE 4 Programmed Temperature Stages in the RC-5 -
Program 1 Start Temp Average Ramp T.sub.sc Duration Stage (.degree.
C.) (.degree. C./min) (.degree. C./min) (min) 1 14.6 0.1 4.0 7000 2
13 0.1 5.6 1500 (from 7000 to 8500) 3 8.1 0.08 10.5 2500 (from 8500
to 11000)
[0094] The three-phase equilibrium temperature (that is, liquid,
vapor, and hydrate) of clathrate hydrates in the natural gas
composition of Table 3 was calculated via methods known to those of
ordinary skill in the art. The three-phase equilibrium temperature
of clathrate hydrates in the natural gas composition was found to
be about 18.6.degree. C. at 70 bars. Moreover, the pressure changes
for liquid, vapor, and hydrate phases were accounted for by
employing a mass balance of the natural gas composition so that
pressure changes were accurately attributed to clathrate hydrate
formation.
[0095] The ability of PAC-AA and PEOx to inhibit clathrate hydrate
formation was evaluated at three subcooling temperatures: about
4.0.degree. C., 5.6.degree. C., and 10.5.degree. C. The ability of
PAC-AA and PEOx to inhibit clathrate hydrate formation was
evaluated at three subcooling temperatures to determine the
induction period and the temperature at which clathrate hydrate
formation occurred. More specifically, in embodiments, the ability
of succinimide-based copolymers to inhibit clathrate hydrate
formation was evaluated by assessing the pressure during each of
the operation stages at the various subcooling temperatures, where
a stable pressure was determined to be indicative of clathrate
hydrate inhibition.
[0096] Results.
[0097] As shown in FIG. 4, PAC-AA and PEOx were not effective
inhibitors of clathrate hydrate formation at any subcooling
temperatures. Clathrate hydrate formation was instantaneous in RC-5
charged with PAC-AA and the brine water composition of Table 2.
While PEOx delayed nucleation of clathrate hydrates, PEOx
eventually failed as a clathrate hydrate formation inhibitor at a
first subcooling temperature of 4.0.degree. C. In addition,
clathrate hydrate growth was very rapid in RC-5 cells charged with
PEOx.
Example 5: Characterization of Succinimide-Based Copolymers'
(SBC-1), (SBC-2) and (SBC-3) and Sodium
Polyaspartate-Ran-Polysuccinimide Inhibition of Clathrate Hydrate
Formation
[0098] Materials and Methods.
[0099] Succinimide-based copolymers having structures (SBC-1),
(SBC-2) and (SBC-3) were synthesized as in Examples 1-3.
Additionally, sodium polyaspartate-ran-polysuccinimide (that is,
SBC-4) was synthesized:
##STR00037##
[0100] More specifically, SBC-4 was synthesized by adding solid
NaOH (about 3.17 g, 79.3 mmol, that is 0.77 molar fraction of
repeating units) portion-wise to PSI (about 10.0 g, 103 mmol
related to repeating units) in water (about 30 mL) at about
0.degree. C. over a period of 5 to 8 minutes under N.sub.2 with
stirring to form a reaction mixture. PSI was synthesized as in
Example 1. The reaction mixture was stirred at room temperature for
3 hours. The reaction mixture was added drop-wise into acetone
(about 200 mL) with stirring. A hygroscopic white reaction product
was filtered, washed with acetone, and dried under vacuum at about
70.degree. C. to a constant weight to obtain SBC-4. (Yield: about
88%).
[0101] The ability of (SBC-1), (SBC-2), (SBC-3), and (SBC-4) to
inhibit clathrate hydrate formation was characterized as in Example
4, except that the RC-5 was programmed to change temperature at
three operation stages as set forth generally in Table 5.
Additionally, each succinimide-based copolymer was tested
separately, that is, two different succinimide-based copolymers
were not paired together in a single test.
TABLE-US-00005 TABLE 5 Programmed Temperature Stages in the RC-5 -
Program 2 Start Temp Average Ramp T.sub.sc Duration Stage (.degree.
C.) (.degree. C./min) (.degree. C./min) (min) 1 14.6 0.1 4.0 1450
to 7000 2 13 0.1 5.6 1450 3 8.1 0.08 10.5 180
[0102] Results.
[0103] As shown in FIG. 5, the succinimide-based copolymers having
structures (SBC-1) and (SBC-2) were effective inhibitors of
clathrate hydrate formation at both a first subcooling temperature
of 4.0.degree. C. and a second subcooling temperature of
5.6.degree. C. Moreover, succinimide-based copolymers having
structures (SBC-1) and (SBC-2) were able to delay nucleation of
clathrate hydrates at a subcooling temperature of 6.0.degree. C.
for more than two days. Further, succinimide-based copolymers
having structures (SBC-1) and (SBC-2) were effective to prevent
clathrate hydrate formation in a pipeline in the field at a second
subcooling temperature of 5.6.degree. C. Additionally, (SBC-3) and
(SBC-4) were effective to prevent clathrate hydrate formation at a
first subcooling temperature of 4.0.degree. C. Moreover, in view of
the pressure changes of FIG. 5, (SBC-3) was more effective than
(SBC-4) to prevent clathrate hydrate formation at a first
subcooling temperature of 4.0.degree. C.
[0104] It will be apparent to those skilled in the art that various
modifications and variations can be made to the embodiments
described in this disclosure without departing from the spirit and
scope of the claimed subject matter. Thus it is intended that this
disclosure cover the modifications and variations of the various
embodiments described provided such modification and variations
come within the scope of the appended claims and their
equivalents.
[0105] It is noted that terms like "generally," "commonly," and
"typically" are not utilized to limit the scope of the claims or to
imply that certain features are critical, essential, or even
important to the structure or function of the claims. Rather, these
terms are merely intended to highlight alternative or additional
features that may or may not be utilized in a particular embodiment
of the present disclosure.
[0106] It is to be further understood that where descriptions of
various embodiments use the term "comprising," or "including" those
skilled in the art would understand that in some specific
instances, an embodiment can be alternatively described using
language "consisting essentially of" or "consisting of."
[0107] Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as reaction conditions,
and so forth used in the disclosure and claims are to be understood
as being modified in all instances by the term "about."
Accordingly, unless indicated to the contrary, the numerical
parameters set forth in this disclosure and claims are
approximations that can vary depending upon the desired properties
sought to be obtained by the presently-disclosed subject
matter.
[0108] It should be understood that every maximum numerical
limitation given throughout this disclosure includes every lesser
numerical limitation, as if such lesser numerical limitations were
expressly written in this disclosure. Every minimum numerical
limitation given throughout this disclosure will include every
greater numerical limitation, as if such greater numerical
limitations were expressly written in this disclosure. Every
numerical range given throughout this disclosure will include every
narrower numerical range that falls within such broader numerical
range, as if such narrower numerical ranges were all expressly
written in this disclosure.
[0109] Unless otherwise defined, all technical and scientific terms
used in this disclosure have the same meaning as commonly
understood by one of ordinary skill in the art to which the claimed
subject matter belongs. The terminology used in this disclosure is
for describing particular embodiments only and is not intended to
be limiting. As used in the disclosure and appended claims, the
singular forms "a," "an," and "the" are intended to include the
plural forms as well, unless the context clearly indicates
otherwise.
* * * * *