U.S. patent application number 16/787999 was filed with the patent office on 2020-09-10 for drag reduction of asphaltenic crude oils.
The applicant listed for this patent is Liquidpower Specialty Products Inc.. Invention is credited to Zhiyi BAO, Timothy L. BURDEN, Wayne R. DREHER, JR., William F. HARRIS, Ray L. JOHNSTON, Stuart N. MILLIGAN, Michael OLECHNOWICZ, Kenneth W. SMITH.
Application Number | 20200284398 16/787999 |
Document ID | / |
Family ID | 1000004842896 |
Filed Date | 2020-09-10 |
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United States Patent
Application |
20200284398 |
Kind Code |
A1 |
BAO; Zhiyi ; et al. |
September 10, 2020 |
DRAG REDUCTION OF ASPHALTENIC CRUDE OILS
Abstract
The process begins by obtaining a first batch of monomers
selected from a group of acrylates with a molecular weight equal to
or less than butyl acrylate and/or methacrylate with a molecular
weight equal to or less than butyl methacrylate. A second batch of
monomers is then selected from a group of acrylates with a
molecular weight greater than butyl acrylate and/or methacrylate
with a molecular weight greater than butyl methacrylate. A mixture
is then prepared by mixing the first batch of monomers and the
second batch of monomers, wherein the second batch of monomers are
greater than 50% by weight of the mixture. Finally, the mixture is
polymerized to produce a drag reducing polymer. The drag reducing
polymer is capable of imparting drag reducing properties in liquid
hydrocarbons.
Inventors: |
BAO; Zhiyi; (Greenwood,
IN) ; MILLIGAN; Stuart N.; (Ponca City, OK) ;
OLECHNOWICZ; Michael; (Ponca City, OK) ; JOHNSTON;
Ray L.; (Ponca City, OK) ; BURDEN; Timothy L.;
(Ponca City, OK) ; SMITH; Kenneth W.; (Tonkawa,
OK) ; HARRIS; William F.; (Palm Harbor, FL) ;
DREHER, JR.; Wayne R.; (Germantown, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Liquidpower Specialty Products Inc. |
Houston |
TX |
US |
|
|
Family ID: |
1000004842896 |
Appl. No.: |
16/787999 |
Filed: |
February 11, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16236026 |
Dec 28, 2018 |
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16787999 |
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15728388 |
Oct 9, 2017 |
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16236026 |
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13209119 |
Aug 12, 2011 |
9784414 |
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15728388 |
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13208951 |
Aug 12, 2011 |
9676878 |
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13209119 |
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11615539 |
Dec 22, 2006 |
8022118 |
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13208951 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F17D 1/16 20130101; C10G
2300/206 20130101; C09K 3/00 20130101; C10G 75/04 20130101; F17D
1/17 20130101; Y10T 137/0391 20150401; C10G 2300/308 20130101 |
International
Class: |
F17D 1/17 20060101
F17D001/17; C09K 3/00 20060101 C09K003/00; C10G 75/04 20060101
C10G075/04; F17D 1/16 20060101 F17D001/16 |
Claims
1. A process, comprising: a) obtaining a first batch of monomers
selected from the group consisting of acrylates with a molecular
weight equal to or less than butyl acrylate, methacrylates with a
molecular weight equal to or less than butyl methacrylate and
combinations thereof; b) obtaining a second batch of monomers
selected from the group consisting of acrylates with a molecular
weight greater than butyl acrylate, methacrylates with a molecular
weight greater than butyl methacrylate and combinations thereof; c)
preparing a mixture comprising the first batch of monomers and the
second batch of monomers wherein the second batch is greater than
50% by weight of the mixture; and d) processing the mixture to
produce a drag reducing polymer capable of imparting drag reducing
properties in liquid hydrocarbons.
2. The process of claim 1, wherein the drag reducing polymer is
introduced into a pipeline, such that the friction loss associated
with the turbulent flow through the pipeline is reduced by
suppressing the growth of turbulent eddies.
3. The process of claim 1, wherein the drag reducing polymer is
added to the liquid hydrocarbon in the range from about 0.1 to
about 500 ppmw.
4. The process of claim 2, wherein the drag reducing polymer
contacts a liquid hydrocarbon in the pipeline to produce a treated
liquid hydrocarbon wherein the viscosity of the treated liquid
hydrocarbon is not less than the viscosity of the liquid
hydrocarbon prior to treatment with the drag reducing polymer.
5. The process of claim 1, wherein the drag reducing polymer has a
solubility parameter within 4 MPa.sup.1/2 of the solubility
parameter of the liquid hydrocarbon.
6. A process, comprising: a) obtaining a first batch of monomers
selected from the group consisting of acrylates with side alkyl
chains having four or less carbons, methacrylates with side alkyl
chains having four or less carbons and combinations thereof; b)
obtaining a second batch of monomers selected from the group
consisting of acrylates with side alkyl chains having greater than
four carbons, methacrylates with side alkyl chains having greater
than four carbons and combinations thereof; c) preparing a mixture
comprising the first batch of monomers and the second batch of
monomers wherein the second batch is greater than 50% by weight of
the mixture; and d) polymerizing the mixture to produce an ultra
high molecular weight polymer wherein the drag reducing polymer is
capable of imparting drag reducing properties in liquid
hydrocarbons.
7. A process of claim 6, wherein monomers of the second batch of
monomers have branched side alkyl chains.
8. The process of claim 6, wherein the drag reducing polymer is
introduced into a pipeline, such that the friction loss associated
with the turbulent flow through the pipeline is reduced by
suppressing the growth of turbulent eddies.
9. The process of claim 8, wherein the drag reducing polymer
contacts a liquid hydrocarbon in the pipeline to produce a treated
liquid hydrocarbon wherein the viscosity of the treated liquid
hydrocarbon is not less than the viscosity of the liquid
hydrocarbon prior to treatment with the drag reducing polymer.
10. The process of claim 6, wherein the drag reducing polymer has a
solubility parameter within 4 MPa.sup.1/2 of the solubility
parameter of the liquid hydrocarbon.
11. The process of claim 6, wherein the drag reducing polymer is
added to the liquid hydrocarbon in the range from about 0.1 to
about 500 ppmw.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application which
claims the benefit of and priority to U.S. application Ser. No.
11/615,539 filed Dec. 22, 2006, entitled "Drag Reduction of
Asphaltenic Crude Oils," and U.S. application Ser. No. 13/208,951,
filed Aug. 12, 2011, entitled "Monomer Selection to Prepare Ultra
High Molecular Weight Drag Reducer Polymer", which are hereby
incorporated by reference in its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to high molecular
weight drag reducers for use in crude oils.
BACKGROUND
[0003] When fluids are transported by a pipeline, there is
typically a drop in fluid pressure due to friction between the wall
of the pipeline and the fluid. Due to this pressure drop, for a
given pipeline, fluid must be transported with sufficient pressure
to achieve the desired throughput. When higher flow rates are
desired through the pipeline, more pressure must be applied due to
the fact that, as flow rates are increased, the difference in
pressure caused by the pressure drop also increases. However,
design limitations on pipelines limit the amount of pressure that
can be employed. The problems associated with pressure drop are
most acute when fluids are transported over long distances. Such
pressure drops can result in inefficiencies that increase equipment
and operation costs.
[0004] To alleviate the problems associated with pressure drop,
many in the industry utilize drag reducing additives in the flowing
fluid. When the flow of fluid in a pipeline is turbulent, high
molecular weight polymeric drag reducers can be employed to enhance
the flow. A drag reducer is a composition capable of substantially
reducing friction loss associated with the turbulent flow of a
fluid through a pipeline. The role of these additives is to
suppress the growth of turbulent eddies, which results in higher
flow rate at a constant pumping pressure. Ultra-high molecular
weight polymers are known to function well as drag reducers,
particularly in hydrocarbon liquids. In general, drag reduction
depends in part upon the molecular weight of the polymer additive
and its ability to dissolve in the hydrocarbon under turbulent
flow. Effective drag reducing polymers typically have molecular
weights in excess of five million.
[0005] Conventional polymeric drag reducers, however, typically do
not perform well in crude oils having a low API gravity and/or a
high asphaltene content. Accordingly, there is a need for improved
drag reducing agents capable of reducing the pressure drop
associated with the turbulent flow of low API gravity and/or
high-asphaltene crude oils through pipelines.
[0006] However not every monomer can be polymerized as drag
reducing polymer. Even when monomers are selected that are known to
have the ability to be polymerized as drag reducing polymers not
all can be shown to impart drag reducing properties. There exists a
need to find which polymers can impart drag reducing
properties.
SUMMARY OF THE INVENTION
[0007] The process begins by obtaining a first batch of monomers
selected from a group of acrylates with a molecular weight equal to
or less than butyl acrylate and/or methacrylate with a molecular
weight equal to or less than butyl methacrylate. A second batch of
monomers is then selected from a group of acrylates with a
molecular weight greater than butyl acrylate and/or methacrylate
with a molecular weight greater than butyl methacrylate. A mixture
is then prepared by mixing the first batch of monomers and the
second batch of monomers, wherein the second batch of monomers are
greater than 50%/n by weight of the mixture. Finally, the mixture
is polymerized to produce a drag reducing polymer. The drag
reducing polymer is capable of imparting drag reducing properties
in liquid hydrocarbons.
[0008] In yet another embodiment a process is taught of obtaining a
first batch of monomers selected from a group of acrylates with
side alkyl chains having four or less carbons and/or methacrylates
with side alkyl chains having four or less. A second batch of
monomers are selected from a group of acrylates with side alkyl
chains having greater than four carbons and/or methacrylates with
side alkyl chains greater than four carbons. A mixture is then
prepared by mixing the first batch of monomers and the second batch
of monomers, wherein the second batch of monomers are greater than
50% by weight of the mixture. Finally, the mixture is polymerized
to produce a drag reducing polymer. The drag reducing polymer is
capable of imparting drag reducing properties in liquid
hydrocarbons.
[0009] In another embodiment a process is taught for selecting
monomers to polymerize into an ultra high molecular weight polymer.
In this embodiment a process is taught of first obtaining a first
batch of monomers selected from a group of acrylates with side
alkyl chains having four or less carbons and/or methacrylates with
side alkyl chains having four or less. A second batch of monomers
are selected from a group of acrylates with side alkyl chains
having greater than four carbons and/or methacrylates with side
alkyl chains greater than four carbons. A mixture is then prepared
by mixing the first batch of monomers and the second batch of
monomers, wherein the second batch of monomers are greater than 50%
by weight of the mixture. Finally, the mixture is polymerized to
produce a drag reducing polymer. The drag reducing polymer is
capable of imparting drag reducing properties in liquid
hydrocarbons.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0010] A preferred embodiment of the present invention is described
in detail below with reference to the attached drawing figures,
wherein:
[0011] FIG. 1 is a normalized filament diameter vs. time plot
depicting the normalized capillary breakup time for untreated San
Joaquin Valley Heavy Crude Oil determined in accordance with the
procedure described in Example 4;
[0012] FIG. 2 is a normalized filament diameter vs. time plot
depicting the normalized capillary breakup time for San Joaquin
Valley Heavy Crude Oil having 500 parts per million by weight
(ppmw) of poly(2-ethylhexyl methacrylate) dissolved therein
determined in accordance with the procedure described in Example 4;
and
[0013] FIG. 3 is a normalized filament diameter vs. time plot
depicting the normalized capillary breakup time for San Joaquin
Valley Heavy Crude Oil having 500 ppmw of a poly(l-decene)
dissolved therein determined in accordance with the procedure
described in Example 4.
[0014] FIG. 4 depicts a process of preparing an ultra high
molecular weight polymer.
[0015] FIG. 5 depicts a process of preparing an ultra high
molecular weight polymer.
DETAILED DESCRIPTION
[0016] In accordance with one embodiment of the present invention,
the pressure drop associated with flowing a liquid hydrocarbon
through a conduit, such as a pipeline, can be reduced by treating
the liquid hydrocarbon with a drag reducing polymer having at least
one heteroatom. In one embodiment, the liquid hydrocarbon can be a
heavy crude oil.
[0017] In one embodiment a process is taught of preparing a drag
reducing polymer to impart maximum drag reduction properties. FIG.
4 is a flowchart depicting this process. Step 201 describes the
first step in the process of obtaining a first batch of monomers
selected from acrylates and/or methacrylates. The selection to use
solely acrylates, solely methacrylates or a combination of
acrylates and methacrylates depends upon different pricing models
and different applications of the ultra high molecular weight
polymer produced at the end. In this embodiment the acrylates can
have a molecular weight equal to or less than butyl acrylate.
Additionally, the methacrylates can have a molecular weight equal
to or less than butyl methacrylate. Examples of acrylates or
methacrylates that can be in the first batch include methyl
acrylate, ethyl acrylate, propyl acrylates, butyl acrylates, methyl
methacrylate, ethyl methacrylate, propyl methacrylates, butyl
methacrylates and combinations and isomeric forms of these
acrylates and methacrylates.
[0018] Step 202 describes the second step in the process wherein a
second batch of monomers is selected from acrylates and/or
methacrylates. In this embodiment the acrylates can have a
molecular weight greater than butyl acrylate. Additionally, the
methacrylates can have a molecular weight greater than butyl
methacrylate. Examples of acrylates or methacrylates that can be in
the second batch include pentyl acrylate, pentyl methacrylate,
isopentyl acrylate, isopentyl methacrylate, hexyl acrylate, hexyl
methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, heptyl
acrylate, heptyl methacrylate, octyl acrylate, octyl methacrylate,
isooctyl acrylate, isooctyl methacrylate, isodecyl acrylate,
isodecyl methacrylate, lauryl acrylate, lauryl methacrylate,
2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, benzyl acrylate,
benzyl methacrylate, 2-phenylethyl acrylate, 2-phenylethyl
methacrylate, tridecyl acrylate, tridecyl methacrylate, isobornyl
acrylate, isobornyl methacrylate, 3,55-trimethylhexyl acrylate,
3,5,5-trimethylhexyl methacrylate, 3,3,5-trimethylcyclohexyl
acrylate, 3,3,5-trimethylcyclohexyl methacrylate and combinations
and isomeric forms of these acrylates and methacrylates.
[0019] A mixture can now be prepared 204 by mixing the first batch
201 with the second batch 202. In this mixture different quantities
of second batch by weight can be used when compared to the total
mixture by weight. In one embodiment the second batch is greater
than 50% by weight of the mixture, in other embodiment the second
batch can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 98%, 99%,
or even 100% of the mixture is of the second batch.
[0020] Finally the mixture is polymerized to produce a drag
reducing polymer 206.
[0021] In yet another embodiment a process is taught of preparing a
drag reducing polymer to impart maximum drag reduction properties.
FIG. 5 is a flowchart depicting this process. Step 301 describes
the first step in the process of obtaining a first batch of
monomers selected from acrylates and/or methacrylates. In this
embodiment the acrylates can have a side alkyl chains having four
or less carbons. Additionally the methacrylates can have side alkyl
chains having four or less carbons.
[0022] Step 302 describes the second step in the process wherein a
second batch of monomers is selected from acrylates and/or
methacrylates. In this embodiment the acrylates can have a side
alkyl chains having greater than four carbons. Additionally the
methacrylates can have side alkyl chains having greater than four
carbons. In yet another embodiment step 303 can also select the
acrylates and methacrylates with side alkyl branching chains versus
those with side alkyl straight chains.
[0023] A mixture can now be prepared 304 by mixing the first batch
301 with the second batch 302. In this mixture different quantities
of second batch by weight can be used when compared to the total
mixture by weight. In one embodiment the second batch is greater
than 50% by weight of the mixture, in other embodiment the second
batch can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 98%, 99%,
or even 100% of the mixture is of the second batch.
[0024] Finally the mixture is polymerized to produce a drag
reducing polymer 306.
[0025] In one embodiment of the present invention, the liquid
hydrocarbon can comprise asphaltene compounds. As used herein,
"asphaltenes" are defined as the fraction separated from crude oil
or petroleum products upon addition of pentane, as described below
in Example 3. While difficult to characterize, asphaltenes are
generally thought to be high molecular weight, non-crystalline,
polar compounds which exist in crude oil. In one embodiment of the
present invention, the liquid hydrocarbon can comprise asphaltene
compounds in an amount of at least about 3 weight percent, in the
range of from about 4 to about 35 weight percent, or in the range
of from 5 to 25 weight percent.
[0026] In another embodiment of the present invention, the liquid
hydrocarbon can comprise heteroatoms. As used herein, the term
"heteroatom" is defined as any atom that is not a carbon or
hydrogen atom. Typically, heteroatoms include, but are not limited
to, sulfur, nitrogen, oxygen, phosphorus, and chlorine atoms. In
one embodiment, the liquid hydrocarbon can comprise sulfur in an
amount of at least about 1 weight percent, in the range of from
about 1 to about 10 weight percent, in the range of from about 1.2
to about 9 weight percent, or in the range of from 1.5 to 8 weight
percent. Additionally, the liquid hydrocarbon can comprise nitrogen
in an amount of at least about 1,300 parts per million by weight
(ppmw), at least about 1,400 ppmw, or at least 1,500 ppmw.
[0027] In another embodiment of the present invention, the liquid
hydrocarbon can comprise one or more metal components. In one
embodiment, the liquid hydrocarbon can comprise metals in an amount
of at least about 1 ppmw, in the range of from about 1 to about
2,000 ppmw, in the range of from about 50 to about 1.500 ppmw, or
in the range of from 100 to 1,000 ppmw. Typical metals include, but
are not limited to, nickel, vanadium, and iron. In one embodiment,
the liquid hydrocarbon can comprise nickel in an amount of at least
about 1 ppmw, in the range of from about 5 to about 500 ppmw, or in
the range of from 10 to 250 ppmw. Additionally, the liquid
hydrocarbon can comprise vanadium in an amount of at least about 1
ppmw, in the range of from about 5 to about 500 ppmw, or in the
range of from 10 to 250 ppmw. Further, the liquid hydrocarbon can
comprise iron in an amount of at least about 1 ppmw, in the range
of from about 2 to about 250 ppmw, or in the range of from 5 to 100
ppmw.
[0028] In another embodiment of the present invention, the liquid
hydrocarbon can comprise a residuum. As used herein, the term
"residuum" is defined as the residual material remaining in the
bottom of a fractionating tower after the distillation of crude oil
as determined by ASTM test method D2892-05. In one embodiment, the
liquid hydrocarbon can comprise at least about 10 weight percent,
at least about 15 weight percent, or in the range of from 20 to 60
weight percent of a residuum having an initial boiling point of at
least about 1,050.degree. F.
[0029] In another embodiment, the liquid hydrocarbon can comprise
conradson carbon. As used herein, the term "conradson carbon" is
defined as the measured amount of carbon residue left after
evaporation and pyrolysis of crude oil as determined by ASTM test
method 0189-05. In one embodiment, the liquid hydrocarbon can
comprise conradson carbon in an amount of at least about 1 weight
percent, in the range of from about 2 to about 50 weight percent,
in the range of from about 3.5 to 45 weight percent, or in the
range of from 5 to 40 weight percent.
[0030] In another embodiment of the present invention, the liquid
hydrocarbon can have a low to intermediate API gravity. As used
herein, the term "API gravity" is defined as the specific gravity
scale developed by the American Petroleum Institute for measuring
the relative density of various petroleum liquids. API gravity of a
liquid hydrocarbon is determined according to the following
formula:
API gravity=(141.5/SG at 60.degree. F.)-131.5
where SG is the specific gravity of the liquid hydrocarbon at
60.degree. F. Additionally, API gravity can be determined according
to ASTM test method D1298. In one embodiment, the liquid
hydrocarbon can have an API gravity of less than about 26.degree.,
in the range of from about 5.degree. to about 25.degree., or in the
range of from 5.degree. to 23.degree..
[0031] In another embodiment of the present invention, the liquid
hydrocarbon can be a component of a fluid mixture that further
comprises a non-hydrocarbon fluid and/or a non-liquid phase. In one
embodiment, the non-hydrocarbon fluid can comprise water, and the
non-liquid phase can comprise natural gas. Additionally, when the
liquid hydrocarbon is a component of a fluid mixture, the liquid
hydrocarbon can account for at least about 50 weight percent, at
least about 60 weight percent, or at least 70 weight percent of the
fluid mixture.
[0032] In another embodiment of the present invention, the liquid
hydrocarbon can have a solubility parameter sufficient to allow at
least partial dissolution of the above mentioned drag reducing
polymer in the liquid hydrocarbon. The solubility parameter
(.delta..sub.2) of the liquid hydrocarbon can be determined
according to the following equation:
.delta..sub.2=[(.DELTA.H.sub.v-RT)/V].sup.1/2
where .DELTA.H.sub.v is the energy of vaporization, R is the
universal gas constant, T is the temperature in Kelvin, and V is
the molar volume. .delta..sub.2 is given in units of MPa.sup.1/2.
The solubility parameter for the liquid hydrocarbon is determined
in accord with the above equation and the description found on
pages 465-467 of Strausz, O. & Lown, M., The Chemistry of
Alberta Oil Sands, Bitumens and Heavy Oils (Alberta Energy Research
Institute, 2003). In one embodiment, the liquid hydrocarbon can
have a solubility parameter of at least about 17 MPa.sup.1/2, or in
the range of from about 17.1 to about 24 MPa.sup.1/2, or in the
range of from 17.5 to 23 MPa.sup.1/2.
[0033] As mentioned above, the liquid hydrocarbon can be a heavy
crude oil. Suitable examples of heavy crude oils include, but are
not limited to, Merey heavy crude, Petrozuata heavy crude, Corocoro
heavy crude, Albian heavy crude, Bow River heavy crude, Maya heavy
crude, and San Joaquin Valley heavy crude. Additionally, the liquid
hydrocarbon can be a blend of heavy crude oil with lighter
hydrocarbons or diluents. Suitable examples of blended crude oils
include, but are not limited to, Western Canadian Select and Marlim
Blend.
[0034] As mentioned above, the liquid hydrocarbon can be treated
with a drag reducing polymer. In one embodiment of the present
invention, the drag reducing polymer can be in the form of a latex
drag reducer comprising a high molecular weight polymer dispersed
in an aqueous continuous phase. The latex drag reducer can be
prepared via emulsion polymerization of a reaction mixture
comprising one or more monomers, a continuous phase, at least one
surfactant, and an initiation system. The continuous phase
generally comprises at least one component selected from the group
consisting of water, polar organic liquids, and mixtures thereof.
When water is the selected constituent of the continuous phase, the
reaction mixture can also comprise a buffer. Additionally, as
described in more detail below, the continuous phase can optionally
comprise a hydrate inhibitor. In another embodiment, the drag
reducing polymer can be in the form of a suspension or solution
according to any method known in the art.
[0035] In one embodiment of the present invention, the drag
reducing polymer can comprise a plurality of repeating units of the
residues of one or more of the monomers selected from the group
consisting of:
##STR00001##
wherein R.sub.1 is H or a C1-C10 alkyl radical, and R.sub.2 is H, a
C1-C30 alkyl radical, a C5-C30 substituted or unsubstituted
cycloalkyl radical, a C6-C20 substituted or unsubstituted aryl
radical, an aryl-substituted C1-C10 alkyl radical, a
--(CH2CH2O).sub.x--R.sub.A or --(CH2CH(CH3)O).sub.x--R.sub.A
radical wherein x is in the range of from 1 to 50 and R.sub.A is H,
a C1-C30 alkyl radical, or a C6-C30 alkylaryl radical;
R.sub.3-arene-R.sub.4 (B)
wherein arene is a phenyl, naphthyl, anthracenyl, or phenanthrenyl,
R.sub.3 is CH.dbd.CH.sub.2 or CH.sub.3--C.dbd.CH.sub.2, and R.sub.4
is H, a C1-C30 alkyl radical, a C5-C30 substituted or unsubstituted
cycloalkyl radical, Cl, SO.sub.3, OR.sub.B, or COOR.sub.C, wherein
R.sub.B is H, a C1-C30 alkyl radical, a C5-C30 substituted or
unsubstituted cycloalkyl radical, a C6-C20 substituted or
unsubstituted aryl radical, or an aryl-substituted C1-C10 alkyl
radical, and wherein R.sub.C is H, a C1-C30 alkyl radical, a C5-C30
substituted or unsubstituted cycloalkyl radical, a C6-C20
substituted or unsubstituted aryl radical, or an aryl-substituted
C1-C10 alkyl radical;
##STR00002##
wherein R.sub.5 is H, a C1-C30 alkyl radical, or a C6-C20
substituted or unsubstituted aryl radical;
##STR00003##
wherein R.sub.6 is H, a C1-C30 alkyl radical, or a C6-C20
substituted or unsubstituted aryl radical;
##STR00004##
wherein R.sub.7 is H or a C.sub.1-C.sub.18 alkyl radical, and
R.sub.8 is H, a C.sub.1-C.sub.18 alkyl radical, or Cl;
##STR00005##
wherein R.sub.9 and R.sub.10 are independently H, a C1-C30 alkyl
radical, a C6-C20 substituted or unsubstituted aryl radical, a
C25-C30 substituted or unsubstituted cycloalkyl radical, or
heterocyclic radicals;
##STR00006##
wherein R.sub.11 and R.sub.17 are independently H, a C1-C30 alkyl
radical, a C6-C20 substituted or unsubstituted aryl radical, a
C5-C30 substituted or unsubstituted cycloalkyl radical, or
heterocyclic radicals;
##STR00007##
wherein R.sub.13 and R.sub.14 are independently H, a C1-C30 alkyl
radical, a C6-C20 substituted or unsubstituted aryl radical, a
C5-C30 substituted or unsubstituted cycloalkyl radical, or
heterocyclic radicals;
##STR00008##
wherein R.sub.15 is H, a C1-C30 alkyl radical, a C6-C20 substituted
or unsubstituted aryl radical, a C5-C30 substituted or
unsubstituted cycloalkyl radical, or heterocyclic radicals;
##STR00009##
wherein R.sub.16 is H, a C1-C30 alkyl radical, or a C6-C20 aryl
radical;
##STR00010##
wherein R.sub.17 and R.sub.18 are independently H, a C1-C30 alkyl
radical, a C6-C20 substituted or unsubstituted aryl radical, a
C5-C30 substituted or unsubstituted cycloalkyl radical, or
heterocyclic radicals;
##STR00011##
wherein R.sub.19 and R.sub.20 are independently H, a C1-C30 alkyl
radical, a C6-C20 substituted or unsubstituted aryl radical, a
C5-C30 substituted or unsubstituted cycloalkyl radical, or
heterocyclic radicals.
[0036] In one embodiment of the present invention, the drag
reducing polymer can comprise repeating units of the residues of
C4-C20 alkyl, C6-C20 substituted or unsubstituted aryl, or
aryl-substituted C1-C10 alkyl ester derivatives of methacrylic acid
or acrylic acid. In another embodiment, the drag reducing polymer
can be a copolymer comprising repeating units of the residues of
2-ethylhexyl methacrylate and the residues of at least one other
monomer. In yet another embodiment, the drag reducing polymer can
be a copolymer comprising repeating units of the residues of
2-ethylhexyl methacrylate monomers and butyl acrylate monomers. In
still another embodiment, the drag reducing polymer can be a
homopolymer comprising repeating units of the residues of
2-ethylhexyl methacrylate.
[0037] In one embodiment of the present invention, the drag
reducing polymer can comprise the residues of at least one monomer
having a heteroatom. As stated above, the term "heteroatom"
includes any atom that is not a carbon or hydrogen atom. Specific
examples of heteroatoms include, but are not limited to, oxygen,
nitrogen, sulfur, phosphorous, and/or chlorine atoms. In one
embodiment, the drag reducing polymer can comprise at least about
10 percent, at least about 25 percent, or at least 50 percent of
the residues of monomers having at least one heteroatom.
Additionally, the heteroatom can have a partial charge. As used
herein, the term "partial charge" is defined as an electric charge,
either positive or negative, having a value of less than 1.
[0038] The surfactant used in the above-mentioned reaction mixture
can include at least one high HLB anionic or nonionic surfactant.
The term "HLB number" refers to the hydrophile-lipophile balance of
a surfactant in an emulsion. The HLB number is determined by the
methods described by W. C. Griffin in J. Soc. Cosmet. Chem., 1, 311
(1949) and J. Soc. Cosmet. Chem., 5, 249 (1954), which are
incorporated herein by reference. As used herein, the term "high
HLB" shall denote an HLB number of 7 or more. The HLB number of
surfactants for use with forming the reaction mixture can be at
least about 8, at least about 10, or at least 12.
[0039] Exemplary high HLB anionic surfactants include, but are not
limited to, high HLB alkyl sulfates, alkyl ether sulfates, dialkyl
sulfosuccinates, alkyl phosphates, alkyl aryl sulfonates, and
sarcosinates. Suitable examples of commercially available high HLB
anionic surfactants include, but are not limited to, sodium lauryl
sulfate (available as RHODAPON LSB from Rhodia Incorporated,
Cranbury, N.J.), dioctyl sodium sulfosuccinate (available as
AEROSOL OT from Cytec Industries, Inc., West Paterson, N.J.),
2-ethylhexyl polyphosphate sodium salt (available from Jarchem
Industries Inc., Newark. N.J.), sodium dodecylbenzene sulfonate
(available as NORFOX 40 from Norman, Fox & Co., Vernon,
Calif.), and sodium lauroylsarcosinic (available as HAMPOSYL L-30
from Hampshire Chemical Corp., Lexington, Mass.).
[0040] Exemplary high HLB nonionic surfactants include, but are not
limited to, high HLB sorbitan esters, PEG fatty acid esters,
ethoxylated glycerine esters, ethoxylated fatty amines, ethoxylated
sorbitan esters, block ethylene oxideipropylene oxide surfactants,
alcohol/fatty acid esters, ethoxylated alcohols, ethoxylated fatty
acids, alkoxylated castor oils, glycerine esters, linear alcohol
ethoxylates, and alkyl phenol ethoxylates. Suitable examples of
commercially available high HLB nonionic surfactants include, but
are not limited to, nonylphenoxy and octylphenoxy poly(ethyleneoxy)
ethanols (available as the IGEPAL CA and CO series, respectively
from Rhodia, Cranbury. N.J.), C8 to C18 ethoxylated primary
alcohols (such as RHODASURF LA-9 from Rhodia Inc., Cranbury, N.J.),
C11 to C15 secondary-alcohol ethoxylates (available as the TERGITOL
15-S series, including 15-S-7, 15-S-9, 15-S-12, from Dow Chemical
Company, Midland, Mich.), polyoxyethylene sorbitan fatty acid
esters (available as the TWEEN series of surfactants from Uniquema,
Wilmington, Del.), polyethylene oxide (25) oleyl ether (available
as SIPONIC Y-500-70 from Americal Alcolac Chemical Co., Baltimore.
Md.), alkylaryl polyether alcohols (available as the TRITON X
series, including X-100, X-165, X-305, and X-405, from Dow Chemical
Company, Midland, Mich.).
[0041] In one embodiment, the initiation system for use in the
above-mentioned reaction mixture can be any suitable system for
generating free radicals necessary to facilitate emulsion
polymerization. Possible initiators include, but are not limited
to, persulfates (e.g., ammonium persulfate, sodium persulfate,
potassium persulfate), peroxy persulfates, and peroxides (e.g.,
tert-butyl hydroperoxide) used alone or in combination with one or
more reducing components and/or accelerators. Possible reducing
components include, but are not limited to, bisulfites,
metabisulfites, ascorbic acid, and sodium formaldehyde sulfoxylate.
Possible accelerators include, but are not limited to, any
composition containing a transition metal having two oxidation
states such as, for example, ferrous sulfate and ferrous ammonium
sulfate. Alternatively, known thermal and radiation initiation
techniques can be employed to generate the free radicals. In
another embodiment, any polymerization and corresponding initiation
or catalytic methods known by those skilled in the art may be used
in the present invention. For example, when polymerization is
performed by methods such as addition or condensation
polymerization, the polymerization can be initiated or catalyzed by
methods such as cationic, anionic, or coordination methods.
[0042] When water is used to form the above-mentioned reaction
mixture, the water can be purified water such as distilled or
deionized water. However, the continuous phase of the emulsion can
also comprise polar organic liquids or aqueous solutions of polar
organic liquids, such as those listed below.
[0043] As previously noted, the reaction mixture optionally can
include a buffer. The buffer can comprise any known buffer that is
compatible with the initiation system such as, for example,
carbonate, phosphate, and/or borate buffers.
[0044] As previously noted, the reaction mixture optionally can
include at least one hydrate inhibitor. The hydrate inhibitor can
be a thermodynamic hydrate inhibitor such as, for example, an
alcohol and/or a polyol. In one embodiment, the hydrate inhibitor
can comprise one or more polyhydric alcohols and/or one or more
ethers of polyhydric alcohols. Suitable polyhydric alcohols
include, but are not limited to, monoethylene glycol, diethylene
glycol, triethylene glycol, monopropylene glycol, and/or
dipropylene glycol. Suitable ethers of polyhydric alcohols include,
but are not limited to, ethylene glycol monomethyl ether,
diethylene glycol monomethyl ether, propylene glycol monomethyl
ether, and dipropylene glycol monomethyl ether.
[0045] Generally, the hydrate inhibitor can be any composition that
when mixed with distilled water at a 1:1 weight ratio produces a
hydrate inhibited liquid mixture having a gas hydrate formation
temperature at 2,000 psia that is lower than the gas hydrate
formation temperature of distilled water at 2,000 psia by an amount
in the range of from about 10 to about 150.degree. F., in the range
of from about 20 to about 80.degree. F., or in the range of from 30
to 60.degree. F. For example, monoethylene glycol qualifies as a
hydrate inhibitor because the gas hydrate formation temperature of
distilled water at 2.000 psia is about 70.degree. F., while the gas
hydrate formation temperature of a 1:1 mixture of distilled water
and monoethylene glycol at 2,000 psia is about 28.degree. F. Thus,
monoethylene glycol lowers the gas hydrate formation temperature of
distilled water at 2,000 psia by about 42.degree. F. when added to
the distilled water at a 1:1 weight ratio. It should be noted that
the gas hydrate formation temperature of a particular liquid may
vary depending on the compositional make-up of the natural gas used
to determine the gas hydrate formation temperature. Therefore, when
gas hydrate formation temperature is used herein to define what
constitutes a "hydrate inhibitor," such gas hydrate temperature is
presumed to be determined using a natural gas composition
containing 92 mole percent methane, 5 mole percent ethane, and 3
mole percent propane.
[0046] In forming the reaction mixture, the monomer, water, the at
least one surfactant, and optionally the hydrate inhibitor, can be
combined under a substantially oxygen-free atmosphere that is
maintained at less than about 1,000 ppmw oxygen or less than about
100 ppmw oxygen. The oxygen-free atmosphere can be maintained by
continuously purging the reaction vessel with an inert gas such as
nitrogen and/or argon. The temperature of the system can be kept at
a level from the freezing point of the continuous phase up to about
60.degree. C., in the range of from about 0 to about 45.degree. C.,
or in the range of from 0 to 30'C. The system pressure can be
maintained in the range of from about 5 to about 100 psia, in the
range of from about 10 to about 25 psia, or about atmospheric
pressure. However, higher pressures up to about 300 psia can be
necessary to polymerize certain monomers, such as diolefins.
[0047] Next, a buffer can be added, if required, followed by
addition of the initiation system, either all at once or over time.
The polymerization reaction is carried out for a sufficient amount
of time to achieve at least about 90 percent conversion by weight
of the monomers. Typically, this time period is in the range of
from between about 1 to about 10 hours, or in the range of from 3
to 5 hours. During polymerization, the reaction mixture can be
continuously agitated.
[0048] The following table sets forth approximate broad and narrow
ranges for the amounts of the ingredients present in the reaction
mixture.
TABLE-US-00001 Ingredient Broad Range Narrow Range Monomer (wt. %
of reaction 10-60% 30-50% mixture) Water (wt. % of reaction 20-80%
50-70% mixture) Surfactant (wt. % of 0.1-10% 0.25-6% reaction
mixture) Initiation system Monomer:Initiator 1 .times. 10.sup.3:1-5
.times. 10.sup.6:1 5 .times. 10.sup.3:1-2 .times. 10.sup.6:1 (molar
ratio) Monomer:Reducing Comp. 1 .times. 10.sup.3:1-5 .times.
10.sup.6:1 5 .times. 10.sup.3:1-2 .times. 10.sup.6:1 (molar ratio)
Accelerator:Initiator 0.001:1-10:1 0.005:1-1:1 (molar ratio) Buffer
0 to amount necessary to reach pH of initiation (initiator
dependent, typically between about 6.5-10) Optional hydrate If
present, the hydrate inhibitor inhibitor can have a hydrate
inhibitor-to-water weight ratio from about 1:10 to about 10:1,
about 1:5 to about 5:1, or 2:3 to 3:2.
[0049] The emulsion polymerization reaction yields a latex
composition comprising a dispersed phase of solid particles and a
liquid continuous phase. The latex can be a stable colloidal
dispersion comprising a dispersed phase of high molecular weight
polymer particles and a continuous phase comprising water. The
colloidal particles can comprise in the range of from about 10 to
about 60 percent by weight of the latex, or in the range of from 40
to 50 percent by weight of the latex. The continuous phase can
comprise water, the high HLB surfactant, the hydrate inhibitor (if
present), and buffer as needed. Water can be present in the range
of from about 20 to about 80 percent by weight of the latex, or in
the range of from about 40 to about 60 percent by weight of the
latex. The high HLB surfactant can comprise in the range of from
about 0.1 to about 10 percent by weight of the latex, or in the
range of from 0.25 to 6 percent by weight of the latex. As noted in
the table above, the buffer can be present in an amount necessary
to reach the pH required for initiation of the polymerization
reaction and is initiator dependent. Typically, the pH required to
initiate a reaction is in the range of from 6.5 to 10.
[0050] When a hydrate inhibitor is employed in the reaction
mixture, it can be present in the resulting latex in an amount that
yields a hydrate inhibitor-to-water weight ratio in the range of
from about 1:10 to about 10:1, in the range of from about 1:5 to
about 5:1, or in the range of from 2:3 to 3:2. Alternatively, all
or part of the hydrate inhibitor can be added to the latex after
polymerization to provide the desired amount of hydrate inhibitor
in the continuous phase of the latex.
[0051] In one embodiment of the present invention, the drag
reducing polymer of the dispersed phase of the latex can have a
weight average molecular weight (M.sub.w) of at least about
1.times.10.sup.6 g/mol, at least about 2.times.10.sup.6 g/mol, or
at least 5.times.10.sup.6 g/mol. The colloidal particles of drag
reducing polymer can have a mean particle size of less than about
10 microns, less than about 1,000 nm (1 micron), in the range of
from about 10 to about 500 nm, or in the range of from 50 to 250
nm. At least about 95 percent by weight of the colloidal particles
can be larger than about 10 nm and smaller than about 500 nm. At
least about 95 percent by weight of the particles can be larger
than about 25 nm and smaller than about 250 nm. The continuous
phase can have a pH in the range of from about 4 to about 10, or in
the range of from about 6 to about 8, and contains few if any
multi-valent cations.
[0052] In one embodiment of the present invention, the drag
reducing polymer can comprise at least about 10,000, at least about
25,000, or at least 50,000 repeating units selected from the
residues of the above mentioned monomers. In one embodiment, the
drag reducing polymer can comprise less than 1 branched unit per
each monomer residue repeating unit. Additionally, the drag
reducing polymer can comprise less than 1 linking group per each
monomer residue repeating unit. Furthermore, the drag reducing
polymer can exhibit little or no branching or crosslinking. Also,
the drag reducing polymer can comprise perfluoroalkyl groups in an
amount in the range of from about 0 to about 1 percent based on the
total number of monomer residue repeating units in the drag
reducing polymer.
[0053] As mentioned above, a liquid hydrocarbon can be treated with
the drag reducing polymer in order to reduce drag associated with
flowing the liquid hydrocarbon through a conduit. In order for the
drag reducing polymer to function as a drag reducer, the polymer
should dissolve or be substantially solvated in the liquid
hydrocarbon. Accordingly, in one embodiment of the present
invention, the drag reducing polymer can have a solubility
parameter that is within about 20 percent, about 18 percent, about
15 percent, or 10 percent of the solubility parameter of the liquid
hydrocarbon, as discussed above.
[0054] The solubility parameter of the drag reducing polymer is
determined according to the Van Krevelen method of the Hansen
solubility parameters. This method of determining solubility
parameters can be found on pages 677 and 683-686 of Brandrup et
al., Polymer Handbook (4.sup.th ed., vol. 2. Wiley-Interscience,
1999), which is incorporated herein by reference. According to
Brandrup et al., the following general equation was developed by
Hansen and Skaarup to account for dispersive forces, polar
interactions, permanent dipole-dipole interactions, and hydrogen
bonding forces in determining solubility parameters:
.delta.=(.delta..sub.d.sup.2+.delta..sub.p.sup.2+.delta..sub.h.sup.2).su-
p.1/2
where .delta. is the solubility parameter, .delta..sub.d is the
term adjusting for dispersive forces. .delta..sub.p is the term
adjusting for polar interactions, and .delta..sub.h is the term
adjusting for hydrogen bonding and permanent dipole-induced dipole.
Systems have been developed to estimate the above terms using a
group contribution method, measuring the contribution to the
overall solubility parameter by the various groups comprising the
polymer. The following equations are used in determining the
solubility parameter of a polymer according to the Van Krevelen
method:
.delta..sub.p=(.SIGMA.F.sup.2.sub.pi).sup.1/2/V
.delta..sub.h=(.SIGMA.E.sub.hi).sup.1/2
.delta..sub.d=(.SIGMA.F.sub.dt/V
[0055] The above equations and an explanation of how they are used
can be found on pages 677 and 683-686 of Brandrup et al. The values
for the variables F and E in the above equations are given in table
4, page 686 of Brandrup et al., based on the different residues
comprising a polymer. For example, a methyl group (--CH.sub.3) is
given the following values: F=420 (J.sup.1/2cm.sup.3/2/mol),
F.sub.pi=0 (J.sup.1/2cm.sup.3/2/mol), E.sub.hi=0 J/mol.
Additionally, the values for the variable V in the above equations
are given in Table 3 on page 685 where, for example, a methyl group
(--CH.sub.3) is given a value of V=33.5 (cm.sup.3/mol). Using these
values, the solubility parameter of a polymer can be
calculated.
[0056] In one embodiment of the present invention, the drag
reducing polymer can have a solubility parameter, as determined
according to the above equations, of at least about 17 MPa.sup.1/2,
in the range of from about 17.1 to about 24 MPa.sup.1/2, or in the
range of from 17.5 to 23 MPa.sup.1/2. Furthermore, the drag
reducing polymer can have a solubility parameter that is within
about 4 MPa.sup.1/2, within about 3 MPa.sup.1/2, or within 2.5
MPa.sup.1/2 of the solubility parameter of the liquid
hydrocarbon.
[0057] The drag reducing polymer can be added to the liquid
hydrocarbon in an amount sufficient to yield a drag reducing
polymer concentration in the range of from about 0.1 to about 500
ppmw, in the range of from about 0.5 to about 200 ppmw, in the
range of from about 1 to about 100 ppmw, or in the range of from 2
to 50 ppmw. In one embodiment, at least about 50 weight percent, at
least about 75 weight percent, or at least 95 weight percent of the
solid drag reducing polymer particles can be dissolved by the
liquid hydrocarbon. In another embodiment, the viscosity of the
liquid hydrocarbon treated with the drag reducing polymer is not
less than the viscosity of the liquid hydrocarbon prior to
treatment with the drag reducing polymer.
[0058] The efficacy of the high molecular weight polymer particles
as drag reducers when added directly to a liquid hydrocarbon is
largely dependent upon the temperature of the liquid hydrocarbon.
For example, at lower temperatures, the polymer dissolves at a
lower rate in the liquid hydrocarbon, therefore, less drag
reduction can be achieved. Thus, in one embodiment of the present
invention, the liquid hydrocarbon can have a temperature at the
time of treatment with the drag reducing polymer of at least about
30.degree. C., or at least 40.degree. C.
[0059] The drag reducers employed in the present invention can
provide significant percent drag reduction. For example, the drag
reducers can provide at least about 5 percent drag reduction, at
least about 15 percent drag reduction, or at least 20 percent drag
reduction. Percent drag reduction and the manner in which it is
calculated are more fully described in Example 5, below.
EXAMPLES
[0060] The following examples are intended to be illustrative of
the present invention in order to teach one of ordinary skill in
the art to make and use the invention and are not intended to limit
the scope of the invention in any way.
Example 1: Preparation of Polymer A and Polymer B
[0061] In this example, two formulations for the materials used in
later examples are detailed. The resulting material in each
procedure is a dispersion of drag reducing polymer in an aqueous
carrier.
Preparation of Polymer A
[0062] Polymerization was performed in a 185-gallon stainless
steel, jacketed reactor with a mechanical stirrer, thermocouple,
feed ports, and nitrogen inlets/outlets. The reactor was charged
with 440 lbs of monomer (2-ethylhexyl methacrylate), 558.1 lbs of
dc-ionized water, 41.4 lbs of Polystep B-5 (surfactant, available
from Stepan Company of Northfield, Illinois), 44 lbs of Tergitol
15-S-7 (surfactant, available from Dow Chemical Company of Midland,
Mich.), 1.86 lbs of potassium phosphate monobasic (pH buffer), 1.46
lbs of potassium phosphate dibasic (pH buffer), and 33.2 grams of
ammonium persulfate, (NH.sub.4).sub.2S.sub.2O.sub.8 (oxidizer).
[0063] The mixture was agitated at 110 rpm to emulsify the monomer
in the water and surfactant carrier. The mixture was then purged
with nitrogen to remove any traces of oxygen in the reactor and
cooled to about 41.degree. F. The agitation was slowed down to 80
rpm and the polymerization reaction was initiated by adding into
the reactor 4.02 grams of ammonium iron(II) sulfate,
Fe(NHe).sub.2(SO.sub.4).sub.2.6H.sub.2O in a solution of 0.010 M
sulfuric acid solution in DI water at a concentration of 558.3 ppm
at a rate of 10 g/min. The solution was injected for 10 hours to
complete the polymerization. The resulting latex was pressured out
of the reactor through a 5-micron bag filter and stored. The
solubility parameter of Polymer A was calculated to be 18.04
MPa.sup.1/2.
Preparation of Polymer B
[0064] Preparation of Polymer B was performed in the same manner as
the preparation of Polymer A above, with the following exception:
the monomer charged to the reactor was an 80/20 weight percent
blend of 2-ethylhexyl methacrylate and n-butyl acrylate. The
solubility parameter of Polymer B was calculated to be 20.55
MPa.sup.1/2.
Example 2: LP 100 and LP 300
[0065] LP 100 FLOW IMPROVER (LP 100) and LP 300 FLOW IMPROVER. (LP
300) underwent various tests described below and were compared to
the experimental drag reducers of the present invention, Polymer A
and Polymer B, as described in Example 1. LP 100 and LP 300 are
drag reducing agents comprising polyalphaolefins. Specifically, LP
100 comprises poly(1-decene) and LP 300 comprises a copolymer of
poly(l-decene) and poly(l-tetradecene). Both LP 100 and LP 300 are
commercially available from ConocoPhillips Specialty Products Inc.
The solubility parameter of the polymer in LP 100 was calculated to
be 16.49 MPa.sup.1/2, and the solubility parameter of the polymer
in LP 300 was calculated to be 16.54 MPa.sup.1/2.
Example 3: Asphaltene Content and Elasticity Response
(Affinity)
[0066] Crude oils ranging in classification from heavy crudes to
light crudes were first tested to determine their respective
concentrations of asphaltene and their API gravities. These same
crude oil samples were also tested to determine their affinity for
drag reducing agents as prepared in Examples 1 and 2. The results
are listed in Table 1 below.
[0067] Asphaltene concentration was determined using pentane
precipitation and filtration. For each measurement listed in Table
1, a 40-fold volume of pentane was added to approximately 16 grams
of crude oil sample. The mixtures were agitated via rolling for an
overnight period, and allowed to set for approximately 24 hours.
The mixtures were then filtered through a 0.8 micrometer filter to
retain the asphaltene. The asphaltenes retained were then weighed,
and the weight percent was calculated based upon the original crude
oil sample weight. API gravity was determined in accord with ASTM
test method D1298.
[0068] The crude oil's affinity for drag reducing agents was
determined by assessing each crude oil's elasticity after being
treated with a drag reducing agent. Four samples of each variety of
crude oil were dosed at room temperature with 5 weight percent of
Polymer A, Polymer B, LP 100, and LP 300 respectively. The samples
were allowed to roll overnight to insure full dissolution of the
drag reducing agent into the samples. After rolling, the samples
were visually inspected for their elastic response by inserting a
hooked-end spatula into the sample and pulling the spatula away
from the bulk of the sample. Some samples yielded a high response,
meaning that a highly elastic "string" or "rope" of crude oil could
be pulled from the sample. Conversely, some samples yielded no
response, meaning that the crude oil merely dripped from the
spatula.
TABLE-US-00002 TABLE 1 Asphaltene Content, API Gravity, and
Elasticity Response ASPHALTENE ELASTICITY RESPONSE CONTENT
(AFFINITY) Crude Oil Test Test API LP LP Polymer Polymer Sample
Type 1 2 Gravity 100 300 A B Merey Heavy 16.8 15.5 16.0.degree.
None None High High Petrozuata Heavy 18.8 18.1 9.1.degree. None
None High High Corocoro Heavy 6.0 6.7 25.1.degree. None None High
High Albian Heavy 11.0 10.6 22.4.degree. None None High High Bow
River Heavy 11.4 10.3 21.8.degree. None None High High Maya Heavy
14.6 15.4 21.9.degree. None None High High Western Heavy 11.5 11.9
20.9.degree. None None High High Canadian Select San Joaquin Heavy
8.9 8.9 13.0.degree. None None High High Valley Marlim Heavy 6.7
6.6 22.2.degree. High High High High Blend West Texas Intermediate
2.8 2.8 31.6.degree. High High Moderate Moderate Sour West Texas
Light 0.5 -- 41.6.degree. High High Moderate Moderate Intermediate
Basrah Light 4.8 -- 31.0.degree. High High Moderate Moderate
[0069] The results in Table 1 tend to show that crude oils having a
higher asphaltene content and/or lower API gravity have a higher
affinity for Polymers A and B than for LP 100 and 300. Evidence of
stronger affinity (i.e., increased elasticity) is generally an
indication of a higher potential for performance as a drag reducing
agent.
Example 4: Extensional Rheometry
[0070] The extensional viscosity (or extensional behavior) of a
fluid treated with a drag reducing polymer is directly related to
the polymer's potential for reducing turbulent drag in the fluid.
If increased extensional behavior is observed in the fluid upon
addition of the drag reducing polymer, this is indicative of
increased potential for drag reduction performance. Conversely, if
no extensional behavior is observed, the potential for drag
reduction performance in that fluid is unlikely. The extensional
behavior of a treated fluid can be determined by capillary breakup
extensional rheometry testing, performed on a HAAKE CaBER 1,
available from Thermo Electron Corp., Newington, N.H., U.S.A.
[0071] The HAAKE CaBER 1 is operated by placing a small quantity of
sample (less than 0.1 ml) between top and bottom circular plates
using a 16 gauge, i-inch long syringe needle. The top plate is
rapidly separated upwardly from the bottom plate at a user-selected
strain rate, thereby forming an unstable fluid filament by imposing
an instantaneous level of extensional strain on the fluid sample.
After cessation of stretching, the fluid at the mid-point of the
filament undergoes an extensional strain rate defined by the
extensional properties of the fluid. A laser micrometer monitors
the midpoint diameter of the gradually thinning fluid filament as a
function of time. The competing effects of surface tension,
viscosity, mass transfer and elasticity can be quantified using
model fitting analysis software.
[0072] In this example, three samples were prepared and tested for
extensional rheometry using a HAAKE CaBER 1. The first sample was
untreated (neat) San Juaquin Valley Heavy (SJVH) crude oil. The
second sample was SJVH crude containing 500 ppmw of the active
polymer found in Polymer A (poly(2-ethylhexyl methacrylate)) as
prepared in Example 1, and the third sample was SJVH crude
containing 500 ppmw of the active polymer found in LP 100
(poly(1-decene)) as described in example 2. According to the
procedure described above, less than 0.1 ml of each of these three
samples was placed between the two plates of the CaBER 1, and the
plates were separated quickly while measuring the diameter of the
resultant filament. For each test, the default instrument settings
were employed, and a Hencky strain of c=0.70 was used. Hencky
strain is defined as:
= ln ( L L 0 ) where L L 0 ##EQU00001##
is the relative extension of the fluid. The diameter of the
resultant filament was measured against time. Each sample in the
above described procedure was tested 10 times to obtain statistical
confidence in the data. The results from these tests are shown in
FIGS. 1 through 3. Additionally, each test was performed at a room
temperature of about 25.degree. C.
[0073] In each of FIGS. 1, 2, and 3, the filament diameter was
normalized, such that a filament diameter of d/d.sub.0 is shown,
where d.sub.0 is the filament diameter at time zero (0 seconds) and
d is the filament diameter at any given time thereafter. The
results from these tests show that the extensional behavior of the
untreated SJVH crude oil and SJVH crude oil containing 500 ppmw the
active polymer found in LP 100 (poly(l-decene)) are very similar
(shown in FIGS. 1 and 3, respectively), indicating that LP 100 does
not have any noticeable potential for reducing drag of heavy crude
oil in a pipeline. However, SJVH having 500 ppmw of the active
polymer found in Polymer A (poly(2-ethylhexyl methacrylate)) shows
a significant increase in extensional rheometry, as shown in FIG.
2. This increase in extensional rheometry indicates an increased
potential for Polymer A to reduce drag of heavy crude oil in a
pipeline.
Example 5: Pipeline Testing
[0074] Pipeline field testing was performed with various diameter
pipelines, and various crude oils, comparing the performance of
Polymers A and B, as prepared in Example 1, with LP 100 and LP 300,
as described in Example 2. The following three tests were
performed, followed by their respective results in tables 2, 3, and
4. For each of the three tests described below, the percent drag
reduction (% DR) was determined by measuring the pressure drop in
the segment of pipe being tested prior to addition of drag reducing
agent (.DELTA.P.sub.base) and measuring the pressure drop in the
segment of pipe being tested after addition of drag reducing agent
(.DELTA.P.sub.treated). The percent drag reduction was then
determined according to the following formula:
%
DR=((.DELTA.P.sub.base-.DELTA.P.sub.treated)/.DELTA.P.sub.base).times.-
100%
Test 1
[0075] Test 1 was conducted in a 12-inch diameter crude oil
pipeline carrying West Texas Intermediate (WTI) crude oil. This
crude oil is a light crude, generally having an API gravity of
about 400. WTI generally has a viscosity of approximately 4.5
centistokes at pipeline temperatures of 65 to 69.degree. F. The
pipeline tests in Test 1 were conducted in a 62-mile segment of the
pipeline running from Wichita Falls, Tx., to Bray, Okla. The
nominal flow rate of the pipeline during the field tests was 2,350
barrels/hr, and the nominal flow velocity in the pipeline was 4.5
ft/s. The following drag reduction performance was achieved:
TABLE-US-00003 TABLE 2 LP 100 v. Polymer A & Polymer B in Light
Crude (WTI) CONCENTRATION DRAG REDUCTION PRODUCT (ppmw) (%) LP 100
4.7 33.8 LP 100 23.5 67.2 Polymer A 40.4 24.4 Polymer A 80.1 36.3
Polymer B 40.2 31.3 Polymer B 81.0 40.4 Polymer B 150.4 45.7
Test 2
[0076] Test 2 was conducted in an 18-inch diameter crude oil
pipeline carrying Albian Heavy Sour (AHS) crude oil blend. This
crude oil blend is a heavy crude oil, generally having an API
gravity of about 22.degree.. AHS generally has a viscosity of
approximately 84 centistokes at a pipeline temperature of
71.degree. F. The pipeline tests in Test 2 were conducted in a
54-mile segment of the pipeline running from Cushing, Okla., to
Marland, Okla. The nominal flow velocity in the pipeline was 4.8
f/s. The nominal calculated Reynolds number for the pipeline was
7,500. The following drag reduction performance was achieved:
TABLE-US-00004 TABLE 3 LP 100 v. Polymer B in Heavy Grade (AHS)
CONCENTRATION DRAG REDUCTION PRODUCT (ppmw) (%) LP 100 41.6 0
Polymer B 35.2 23.1 Polymer B 100.0 42.5
Test 3
[0077] Test 3 was conducted in an 8-inch diameter crude oil
pipeline carrying San Joaquin Valley Heavy (SJVH) crude oil blend.
This crude oil blend is a heavy crude oil, generally having an API
gravity of about 13.degree.. SJVH generally has a viscosity of
approximately 100 centistokes at a pipeline temperature of
165.degree. F. The pipeline tests in Test 3 were conducted in a
14-mile segment of the pipeline running from the Middlewater pump
station to the Junction pump station, both in California. The
nominal flow rate of the pipeline during Test 3 was 1,300
barrels/hr, and the nominal flow velocity in the pipeline was 5.6
ft/s. The nominal calculated Reynolds number for the pipeline was
4,000. The following drag reduction performance was achieved:
TABLE-US-00005 TABLE 4 LP 300 v. Polymer A & Polymer B in Heavy
Crude (SJVH) CONCENTRATION DRAG REDUCTION PRODUCT (ppmw) (%) LP 300
187.0 0 Polymer A 50.0 28.5 Polymer A 100.0 39.5 Polymer B 50.0
28.8 Polymer B 100 36.7
[0078] Comparing the above three tests, the results listed in Table
2 tend to show that the drag reduction achieved by addition of LP
100 product in light crude oil yields slightly more favorable
results than either of the EXP products. However, when heavy crude
oils are used, as shown in Tables 3 and 4, the use of Polymers A or
B results in higher percentages of drag reduction than either of
the LP products.
Example 7: Alkyl Acrylates
[0079] The following monomers were emulsion polymerized and tested
for their drag reducing properties:
TABLE-US-00006 % Drag Re- duction in Diesel WCS WTI Alkyl Carbon
Alkyl Inherent at Oil Oil Acrylate Number Chain Viscosity 2 ppm
Affinity Affinity n-Butyl 4 Straight 14.2 0 0 0 Acrylate tert-Butyl
4 Branched 18.5 0 1.0 0 Acrylate 2-ethyl- 8 Branched 11.5 12.9 4.5
1.5 hexyl Acrylate
[0080] As it is shown in the above mentioned example acrylates with
alkyl chains larger than 4 provided the greatest amount of drag
reduction.
Example 8: Alkyl Methacrylates
[0081] The following polymers were emulsion polymerized and tested
for their drag reducing proerties:
TABLE-US-00007 % Drag Re- duction in Alkyl Diesel WCS WTI Metha-
Carbon Alkyl Inherent at Oil Oil crylate Number Chain Viscosity 2
ppm Affinity Affinity Methyl 1 Straight 14.4 0 0 0 Metha- crylate
n-Butyl 4 Straight 12.7 0 1.0 0 Metha- crylate iso-Butyl 4 Branched
18.7 0 1.0 0 Metha- crylate Hexyl 6 Straight 19.5 31.9 6.5 2.0
Metha- crylate 2-Ethyl- 8 Branched 18.6 36.8 7.0 1.5 hexyl Metha-
crylate Isodecyl 10 Branched 14.3 24.8 9.5 2.0 Metha- crylate
Lauryl 12 Straight 12.6 17.2 9.0 3.0 Metha- crylate
[0082] As it is shown in the above mentioned example acrylates with
alkyl chains larger than 4 provided the greatest amount of drag
reduction.
Numerical Ranges
[0083] The present description uses numerical ranges to quantify
certain parameters relating to the invention. It should be
understood that when numerical ranges are provided, such ranges are
to be construed as providing literal support for claim limitations
that only recite the lower value of the range as well as claims
limitation that only recite the upper value of the range. For
example, a disclosed numerical range of 10 to 100 provides literal
support for a claim reciting "greater than 10" (with no upper
bounds) and a claim reciting "less than 100" (with no lower
bounds).
[0084] The present description uses specific numerical values to
quantify certain parameters relating to the invention, where the
specific numerical values are not expressly part of a numerical
range. It should be understood that each specific numerical value
provided herein is to be construed as providing literal support for
a broad, intermediate, and narrow range. The broad range associated
with each specific numerical value is the numerical value plus and
minus 60 percent of the numerical value, rounded to two significant
digits. The intermediate range associated with each specific
numerical value is the numerical value plus and minus 30 percent of
the numerical value, rounded to two significant digits. The narrow
range associated with each specific numerical value is the
numerical value plus and minus 15 percent of the numerical value,
rounded to two significant digits. For example, if the
specification describes a specific temperature of 62.degree. F.,
such a description provides literal support for a broad numerical
range of 25.degree. F. to 99.degree. F. (62.degree. F.+/-37.degree.
F.), an intermediate numerical range of 43.degree. F. to 81.degree.
F. (62.degree. F.+/-19.degree. F.), and a narrow numerical range of
53'F to 71.degree. F. (62.degree. F.+/-9.degree. F.). These broad,
intermediate, and narrow numerical ranges should be applied not
only to the specific values, but should also be applied to
differences between these specific values. Thus, if the
specification describes a first pressure of 110 psia and a second
pressure of 48 psia (a difference of 62 psi), the broad,
intermediate, and narrow ranges for the pressure difference between
these two streams would be 25 to 99 psi, 43 to 81 psi, and 53 to 71
psi, respectively.
Definitions
[0085] As used herein, the terms "comprising," "comprises," and
"comprise" are open-ended transition terms used to transition from
a subject recited before the term to one or more elements recited
after the term, where the element or elements listed after the
transition term are not necessarily the only elements that make up
the subject.
[0086] As used herein, the terms "including," "includes," and
"include" have the same open-ended meaning as "comprising,"
"comprises," and "comprise."
[0087] As used herein, the terms "having," "has," and "have" have
the same open-ended meaning as "comprising," "comprises." and
"comprise."
[0088] As used herein, the terms "containing," "contains," and
"contain" have the same open-ended meaning as "comprising,"
"comprises," and "comprise."
[0089] As used herein, the terms "a," "an." "the," and "said" mean
one or more.
[0090] As used herein, the term "and/or," when used in a list of
two or more items, means that any one of the listed items can be
employed by itself or any combination of two or more of the listed
items can be employed. For example, if a composition is described
as containing components A, B, and/or C, the composition can
contain A alone; B alone; C alone; A and B in combination; A and C
in combination; B and C in combination; or A, B, and C in
combination.
[0091] The preferred forms of the invention described above are to
be used as illustration only, and should not be used in a limiting
sense to interpret the scope of the present invention. Obvious
modifications to the exemplary embodiments, set forth above, could
be readily made by those skilled in the art without departing from
the spirit of the present invention.
[0092] The inventors hereby state their intent to rely on the
Doctrine of Equivalents to determine and assess the reasonably fair
scope of the present invention as pertains to any apparatus not
materially departing from but outside the literal scope of the
invention as set forth in the following claims.
* * * * *