U.S. patent application number 12/968671 was filed with the patent office on 2011-12-22 for tunable surfactants for oil recovery applications.
Invention is credited to Michael C. Berg, William A. Mowers, Kevin T. Petersen, David Soane, Kristoffer K. Stokes.
Application Number | 20110308810 12/968671 |
Document ID | / |
Family ID | 39184122 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110308810 |
Kind Code |
A1 |
Stokes; Kristoffer K. ; et
al. |
December 22, 2011 |
TUNABLE SURFACTANTS FOR OIL RECOVERY APPLICATIONS
Abstract
The systems and methods described herein provide for modified
lignins and other compositions that may be useful as surfactants.
These compositions have particular utility for energy-related
applications. In embodiments, they may be useful for enhanced oil
recovery. In embodiments, they may be useful for extracting bitumen
from oil sands. In embodiments, they may be useful for
environmental remediation.
Inventors: |
Stokes; Kristoffer K.;
(Jamaica Plain, MA) ; Soane; David; (Chestnut
Hill, MA) ; Berg; Michael C.; (Somerville, MA)
; Petersen; Kevin T.; (Cheshire, CT) ; Mowers;
William A.; (Lynn, MA) |
Family ID: |
39184122 |
Appl. No.: |
12/968671 |
Filed: |
December 15, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11850749 |
Sep 6, 2007 |
7871963 |
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12968671 |
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60843815 |
Sep 12, 2006 |
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Current U.S.
Class: |
166/369 ;
507/106; 530/504 |
Current CPC
Class: |
C07C 29/80 20130101;
C07C 29/84 20130101; C07C 29/80 20130101; C07C 29/76 20130101; C07C
29/76 20130101; C07C 31/08 20130101; C07C 29/84 20130101; C07C
31/08 20130101; C07C 31/08 20130101; Y10T 428/249953 20150401 |
Class at
Publication: |
166/369 ;
507/106; 530/504 |
International
Class: |
E21B 43/00 20060101
E21B043/00; C08H 7/00 20110101 C08H007/00; C09K 8/08 20060101
C09K008/08 |
Claims
1. A petroleum recovery medium comprising water and a pH sensitive
surfactant, said surfactant characterized by one or more
hydrophobic region(s) or group(s) having an affinity to petroleum
and a plurality of ionizable, hydrophilic group(s), the petroleum
recovery medium being capable of (1) forming an emulsion with water
and petroleum at a first pH and (2) demulsifying said emulsion at a
second pH.
2. The medium in accordance with claim 1, wherein the surfactant is
a carboxylated lignin.
3. The medium in accordance with claim 2, wherein the surfactant is
produced by reacting a lignin with an anhydride.
4. The medium in accordance with claim 3, wherein the anhydride is
a succinic anhydride.
5. The medium in accordance with claim 4, wherein the anhydride is
an alkylated succinic anhydride.
6. The medium in accordance with claim 3, wherein the lignin is a
kraft lignin characterized by hydroxyl groups.
7. The medium in accordance with claim 6, wherein between about 50
and 100% of the hydroxyl groups are functionalized.
8. The medium in accordance with claim 2, wherein the surfactant
forms the emulsion at a pH of about 7 and demulsifies at a pH of
less than about 5.
9. The medium in accordance with claim 2, further characterized by
a hydrophilic polymer substituent.
10. The medium in accordance with claim 9, wherein the hydrophilic
polymer substituent is selected from the group consisting of a
polyethylene oxide and a polypropylene oxide.
11. The medium in accordance with claim 10, wherein the hydrophilic
polymer substituent is selected from the group consisting of a
polyethylene oxide diglycidyl ether and a polypropylene oxide
diglycidyl ether.
12. The medium in accordance with claim 11, wherein the hydrophilic
polymer substituent has a molecular weight between about 700 and
2500 g/mol.
13. The medium in accordance with claim 2, further characterized by
an inert substituent.
14. The medium in accordance with claim 12, wherein the inert
substituent is selected from the group consisting of a silicone, a
siloxane, and a perfluorinated polymer.
15. The medium in accordance with claim 13, wherein the inert
substituent is a siloxane and is added in an amount less than 25%
by weight to the surfactant.
16. The medium in accordance with claim 1, comprising a surfactant
produced by a process comprising reacting a lignin with a succinic
acid anhydride, a hydrophilic polymer substituent selected from the
group consisting of a polyethylene oxide diglycidyl ether and a
polypropylene oxide diglycidyl ether and a siloxane.
17. The medium in accordance with claim 1, wherein the medium is a
drilling fluid.
18. A process of producing a carboxylated lignin surfactant
comprising reacting a lignin with a succinic acid anhydride, a
hydrophilic polymer substituent selected from the group consisting
of a polyethylene oxide diglycidyl ether and a polypropylene oxide
diglycidyl ether and a siloxane.
19. A method of petroleum recovery, comprising: (a) making an
emulsion at a first pH comprising contacting petroleum and an
emulsion producing amount of a petroleum recovery medium comprising
water and a surfactant, said surfactant characterized by one or
more hydrophobic region(s) or group(s) having an affinity to said
petroleum and a plurality of ionizable, hydrophilic group(s), the
drilling fluid being capable of forming an emulsion with said water
and said petroleum at said first pH; (b) breaking the emulsion by
changing the pH to a second pH; (c) isolating the petroleum
containing phase.
20. The method of petroleum recovery in accordance with claim 19,
wherein the petroleum recovery medium is added to a
petroleum-containing underground formation.
21. The method of petroleum recovery in accordance with claim 19,
wherein the petroleum recovery medium is added to a tar sand or oil
sand.
22. The method of petroleum recovery in accordance with claim 19,
wherein the petroleum recovery medium is added to oil laden debris.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 11/850,749, filed Sep. 6, 2007, which claims the benefit of
U.S. Provisional Application No. 60/843,815, filed on Sep. 12,
2006. The entire teachings of the above applications are
incorporated herein by reference.
FIELD OF APPLICATION
[0002] This application relates generally to surfactant
compositions useful for applications in the energy industry
involving petroleum production and environmental remediation.
BACKGROUND
[0003] As world-wide energy needs continue to grow, there is
concern that demand for energy may outstrip its supply.
Technologies for improving the efficiencies of petroleum production
become increasingly valuable. Moreover, in light of the impact of
petroleum production on the environment, technologies for
environmental remediation are also desirable.
[0004] Oil extraction from deposits in source rock presently takes
place in stages. Typically, the initial stage, known as primary
recovery, involves drilling a hole from the surface to a subsurface
reservoir, where oil is trapped under pressure. This hole may be
known as a well or a wellbore. A subsurface oil reservoir is
understood to be an underground pool of a liquid mix of
hydrocarbons and other impurities that is contained within a
geological formation beneath the surface of the earth. The
subsurface reservoir may be penetrated by one or more wells,
perforations that contact the subsurface reservoir and permit the
removal of the liquid and gas hydrocarbons resident therein. When
an oil reservoir containing oil under pressure is tapped by a drill
hole, the reservoir's pressure forces its contents through the
drill hole to the surface for collection. This process may continue
until the pressure within the reservoir is no longer sufficient to
expel the oil contained therein. When the pressure in the reservoir
is depleted but there is still oil available, pumps may be used to
bring the oil to the surface.
[0005] The wells used for removing the contents of the reservoir
may also be used for injecting substances into the reservoir to
enhance the extraction of its contents. For example, such materials
as water, brine, steam, and mobilization chemicals such as
surfactants may be injected. A well from which oil is recovered is
known as a production well. A well through which substances are
injected is known as an injection well.
[0006] Injection techniques are particularly useful when the
pressure within the reservoir decreases so that supplemental
measures are useful to increase the recovery of oil contained
within the reservoir. Techniques used under these circumstances may
be termed secondary recovery techniques. For example, the pressure
within the reservoir may be increased by injecting water, steam or
gas into the reservoir. Injecting water into a well to increase
recovery of oil is called "waterflood." Other secondary recovery
techniques may include flooding with polymers, alkali, or other
chemical solutions, and various thermal processes. Alternatively,
gases such as carbon dioxide, natural gas or nitrogen may be
injected into the reservoir, where they expand and push additional
oil out through the production wellbores, and where they may affect
the viscosity of the remaining oil, thereby improving its flow rate
on egress. The combination of primary and secondary oil recovery
only removes a certain amount of the total oil content from an oil
reservoir, approximately between 20% and 80%.
[0007] Hence, a large amount of the original oil remains in the
reservoir after secondary recovery techniques. In large oil fields,
over a billion barrels of oil may remain after secondary recovery
efforts. The percentage of unrecovered hydrocarbons is largest in
oil fields with complex lithologies, and the petroleum fractions
left behind tend to be the heavier hydrocarbon materials and those
liquid materials that may be trapped by high capillary forces in
the micron-sized pores in the reservoir rock or adsorbed onto
mineral surfaces through irreducible oil saturation. There may also
be pools of bypassed oil within the rock formations surrounding the
main reservoir. Retrieving the normally immobile oil residing in
the oil field after primary and secondary recovery is referred to
herein as "tertiary recovery" or "enhanced oil recovery" (EOR).
[0008] Current EOR techniques may be able to remove an additional
5% to 20% of the oil remaining in a reservoir. Techniques currently
available leave significant amounts of oil behind. Such techniques
may also be expensive to carry out and inefficient. For example,
bacteria may be used to free the oil trapped in rock pores or
adsorbed onto mineral surfaces, and this freed oil may be dislodged
with water during waterflooding. Such bacteria are introduced into
the well from external sources. The bacteria may also create
methane gas that can be recovered. As another example, gelled or
crosslinked water-soluble polymers may be introduced that alter the
permeability of geological formations to make waterflooding more
effective. Polymers, either preformed or gelled/crosslinked in
situ, may be introduced into the reservoir from external sources.
Both bacterial techniques and polymer-based techniques are costly
processes, though.
[0009] As another example, EOR may take place using a variety of
externally-introduced chemical agents that may be used to increase
the efficacy of waterflooding. These agents fall into two
categories. One type of chemical agent may be a surfactant material
that can alter the surface tension that adheres oil, water and rock
together within the formation. The second type of chemical agent is
viscous enough to slow the passage of water through the rock matrix
so that the trapped oil can be pushed out more effectively.
Chemical techniques for EOR may also be disadvantageous. Existing
surfactants, for example, may adversely affect properties of
oil-bearing rock formations and thereby damage reservoirs. Also,
these surfactants, being of low viscosity, may not be effective in
pushing the oil out of the pores where it is trapped. In addition,
these surfactants may not be able to function effectively under the
high temperature and high pressure conditions where they are used.
Certain surfactants, such as petroleum sulfonates or their
derivatives, are also particularly difficult to remove from the
desired petroleum once it has been extracted. As an additional
problem, surfactants are typically used with waterflooding
techniques, leading to the production of highly stable emulsions
containing mostly water with very little oil. In sum, with existing
surfactant techniques, it is difficult to extract oil from rock and
difficult to remove it from the water used to flush it out of the
reservoir. The costs associated with these processes and their
technical limitations have limited the widespread adaptation of
these EOR techniques.
[0010] Many variations on the aforesaid systems and methods have
been proposed. For example, U.S. Patent Publication No. 20070079964
discloses the use of aliphatic anionic surfactants. U.S. Patent
Publication No. 20060046948 discloses the use of alkyl
polyglycosides. U.S. Pat. No. 6,225,263 discloses the use of
alkylglycol ethers. U.S. Pat. No. 6,475,290 discloses the use of
lignin sulfonates. U.S. Pat. No. 5,911,276 discloses the use of
lignin. U.S. Pat. No. 4,790,382 discloses the use of alkylated,
oxidized lignin.
[0011] In addition to petroleum reservoirs as described above,
petroleum may be extracted from formations called oil sands or tar
sands. Oil sands, also called tar sands, are mixtures of sand or
clay, water and extremely heavy crude oil (e.g., bitumen). For
example, a major formation of oil sands in Alberta, Canada,
contains material that is approximately 90% sand, 10% crude oil,
and water. Oil sand formations are understood to comprise
naturally-occurring petroleum deposits in which the lighter
fractions of the oil have been lost, and the remaining heavy
fractions have been partially degraded by bacteria. The crude oil
is extra heavy crude and can be characterized as a naturally
occurring viscous mixture of hydrocarbons that are generally
heavier than pentane. The petroleum contained in these formations
is a viscous, tar-like substance that is admixed with clay, sand
and other inorganic particulate matter. Accordingly, it is harder
to refine and generally of lesser quality than other crudes. While
there is great variability, depending on the oil sands source, the
mineral matter in oil sands typically includes a fairly uniform
white quartz sand, silt, clay, water, bitumen and other trace
minerals, such as zirconium, pyrite and titanium. The bitumen
content of oil sands may be as high as 18%, or it can be
substantially lower.
[0012] As described above, conventional crude oil in reservoirs may
be readily extracted by boring wells into the formation, because
the light or medium density oil in such reservoirs can flow freely
out. By contrast, there is no free-flowing oil in an oil sand
formation. Instead, these deposits must be strip mined or their
petroleum content must be treated so that it flows.
[0013] In the strip mining method, oil sands are dug up from a
surface mine and are transported and washed to remove the oil.
Mining methods typically involve a number of steps, beginning with
excavation and ore size reduction, followed by slurry formation
with water and sodium hydroxide. The slurry is then treated with
flotation agents (typically kerosene), frothing agents
(methylisobutyl carbinol is common), and air is passed through the
slurry to create a bitumen froth. This mixture is transported
through approximately 2 kilometers of pipeline, creating a
mechanical as well as chemical separation of the bitumen from the
inorganic sand and silt. The pipeline leads to a separation tank
that allows the froth to be skimmed off while the inorganic
material falls to the bottom. Since the bitumen is much heavier
than standard crude oil, it must be either mixed with a lighter
petroleum or chemically processed so that it is flowable enough for
transport. Further processing removes water and solids, following
which the bitumen may be processed to form synthetic crude oil.
Using this method, about two tons of tar sands produce one barrel
of oil.
[0014] Much of the oil sands reserve is located below the surface,
so the strip mining technique is not applicable. For these
formations, a variety of in situ methods are available to extract
bitumen from underground formations via specialized drilling and
extraction techniques. These methods typically use a great amount
of energy in the form of steam to heat the trapped bitumen. The
heated bitumen has a lower viscosity and can then flow, slowly, to
a production well. The steam-softened bitumen forms an emulsion
with the water from the steam and drains to a wellhead within the
formation from which it is pumped to the surface. This emulsion has
similar characteristics to the water-bitumen emulsion produced
during strip-mining. The emulsion may be treated similarly, with
addition of NaOH and the application of petroleum solvents to make
the material flowable.
[0015] Mining methods work well for "high-grade" oil sands, i.e.,
oil sands that have high bitumen content and low clay content.
However, such high-grade materials afford a best-case scenario. In
reality, the excavated oil sands exist as a mixture of high and low
grade materials ("mixed-grade" oil sands). The "low-grade"
materials with their lower bitumen content and high clay content
are more difficult to extract using conventional methods. It tends
to be impractical to separate the low-grade and the high-grade
materials within mixed-grade oil sands, so the low-grade materials
are simply carried along with the high-grade and not subjected to
processing. Increasing production from this type of oil sand can
create enormous opportunities for companies that have rights to
less desirable grades of oil sands.
[0016] Many of the problems that affect oil production, such as
those discussed above, also apply to environmental remediation
following oil production and other environmental remediation
problems, such as may exist following oil spills. Methods have been
proposed for dealing with oil spills, such as those disclosed in
U.S. Pat. No. 4,925,343 and U.S. Pat. No. 3,788,984.
[0017] As well, following petroleum production, there may be
discharge of solid materials contaminated with petroleum products.
In off-shore deep-water production, oil-laden mud that is wet with
sea water must be barged to land, where energy-intensive processing
takes place to allow stripping of oil from sand/clay particles and
evaporation of water. Only after the mud is cleared of oil can it
be dumped into landfill. Despite the inefficiencies, this
production scheme is mandated by the EPA. Oil-soaked mud can not
simply be put back into the ocean at the point of production
without first making sure that all the adhered oil is removed. At
present, no technology exists that permits ready stripping of oil
from mud within the confines of a production platform.
[0018] Materials contaminated with petroleum, its byproducts or
residues from its production can have substantial adverse impact on
the environment. It would be advantageous to provide economical
methods for treating such materials to remove the hydrocarbon
contamination in a rapid and effective manner while avoiding the
use of chemical or other agents that may inflict further damage on
the environment.
SUMMARY
[0019] The invention relates to the discovery of certain
surfactants that are capable of producing a petroleum based
emulsion at a first pH and quickly demulsifying at a second pH.
Thus the invention includes a petroleum recovery medium comprising
a pH sensitive surfactant, said surfactant characterized by one or
more hydrophobic region(s) or group(s) having an affinity to
petroleum and a plurality of ionizable, hydrophilic group(s), the
petroleum recovery medium being capable of (1) forming an emulsion
with water and petroleum at a first pH and (2) demulsifying said
emulsion at a second pH. Preferably, the surfactant is a
carboxylated lignin, such as can be produced by reacting a lignin
with an anhydride, such as a succinic anhydride or alkylated
succinic anhydride. Preferred lignin include a kraft lignin
characterized by hydroxyl groups. In one embodiment, between about
50 and 100% of the lignin hydroxyl groups are functionalized.
Preferably, the surfactant forms the emulsion at a pH of about 7
and demulsifies at a pH of less than about 5. In embodiments, a
hydrophilic polymer substituent, such as a polyethylene oxide and a
polypropylene oxide, including a polyethylene oxide diglycidyl
ether and a polypropylene oxide diglycidyl ether, is added to the
surfactant. The hydrophilic polymer substituent preferably has a
molecular weight between about 700 and 2500 g/mol. The surfactant
can also be characterized by an inert substituent, such as a
silicone, a siloxane, and a perfluorinated polymer, for example,
added in an amount less than 25% by weight to the surfactant. In
embodiments, the petroleum recovery material may be a drilling
fluid.
[0020] For example, the surfactant can be produced by a process
comprising reacting a lignin with a succinic acid anhydride, a
hydrophilic polymer substituent selected from the group consisting
of a polyethylene oxide diglycidyl ether and a polypropylene oxide
diglycidyl ether and a siloxane. The invention also relates to a
process of producing a carboxylated lignin surfactant comprising
reacting a lignin with a succinic acid anhydride, a hydrophilic
polymer substituent selected from the group consisting of a
polyethylene oxide diglycidyl ether and a polypropylene oxide
diglycidyl ether and a siloxane.
[0021] The invention also relates to a method of petroleum
recovery, comprising:
[0022] (a) making an emulsion at a first pH comprising contacting
petroleum, water and an emulsion producing amount of a petroleum
recovery medium comprising a surfactant, said surfactant
characterized by one or more hydrophobic region(s) or group(s)
having an affinity to said petroleum and a plurality of ionizable,
hydrophilic group(s), the petroleum recovery medium being capable
of forming an emulsion with said water and said petroleum at said
first pH;
[0023] (b) breaking the emulsion by changing the pH to a second
pH;
[0024] (c) isolating the petroleum containing phase.
[0025] In embodiments, the method may include adding the petroleum
recovery medium to a petroleum-containing underground formation. In
embodiments, the method may include adding the petroleum recovery
medium to a tar sand or oil sand. In embodiments, the method may
include adding the petroleum recovery medium to oil laden
debris.
DESCRIPTION
[0026] Disclosed herein are systems and methods useful in energy
applications. In one embodiment, the invention provides for an
amphiphilic petroleum recovery medium characterized by a surfactant
comprising hydrophobic region(s) or group(s) having an affinity to
hydrocarbon oils (e.g., particularly hydrocarbon groups, aromatic
hydrophobic groups, lignin and its derivatives) and hydrophilic
group(s), the petroleum recovery medium being capable of forming an
emulsion with water (e.g., flood water or salt water) and a
hydrocarbon oil (e.g., fossil fuels, such as bitumen) at the pH of
use (e.g., within an oil deposit) and being capable of separation
(e.g. breaking of an emulsion into two distinct phases) upon the
modification of the pH (e.g., raising or lowering pH). That is, the
preferred petroleum recovery media of the inventions comprise a
compound which possess surfactant or emulsification properties at
one pH and does not possess such properties at a second pH. In
embodiments, petroleum recovery medium comprises a compound, as
discussed above, wherein the hydrophobic region comprises a
hydrocarbon and the hydrophilic region comprises an ionizable
functional group which allows pH-induced switching.
[0027] The ionizable group can be cationic or anionic. Examples of
cationic groups are preferably carbon containing acids, such as
carboxylic acids. Sulfur containing acids, particularly stable
sulfur containing acids, such as lignin sulfates and sulfonates,
are excluded. Alternatively, applications could exist where
ionizable groups such as amines (such as primary or secondary
amines) or phosphines can be employed as the pH sensitive switching
agent.
[0028] The petroleum recovery medium is preferably selected to
contain atoms selected from the group consisting of carbon,
hydrogen and oxygen, thereby avoiding the need for removing sulfur
or nitrogen from the resulting product.
[0029] Acidic groups may be used to provide a hydrophilic portion
for surfactant water stability. Such groups provide the switching
ability necessary for the hydrophobic-hydrophilic transition
leading to emulsification and demulsification of oil in water and
water in oil mixtures. In an embodiment, the acids groups are
derived from carboxylic acids. Preferably, the active surfactant
mixture possesses surfactant properties (e.g., it readily forms an
emulsion with water and the hydrocarbon oil) at a pH between about
5 and 9, preferably about 6 and 8, such as about 7 and does not
possess such surfactancy (e.g., the phases separate) after pH
modification. In an example where the ionizable group is an acid,
this transition can occur at lower acidic pH values, preferably
less than 5. If the ionizable group includes an amine
functionality, this transition can occur upon raising the pH,
preferably above 9. In embodiments, the character of the molecule,
or surfactant properties, may be altered by changing the pH of the
solution in which the surfactant resides.
[0030] Preferred petroleum recovery media of the invention comprise
a compound characterized by a polymeric aromatic hydrophobic
backbone. Such compounds of the invention can be made by reacting a
first starting material, such as an aromatic hydrophobic polymer
comprising a plurality of first functional groups, such as hydroxyl
groups or amines, and a second starting material characterized by a
second functional group which will react with said first functional
group and cause a covalent bond to form and the presentation of an
ionizable group. A preferred polymeric aromatic hydrophobic polymer
includes lignins.
[0031] In embodiments, the systems and methods described herein may
be useful for enhanced oil recovery. In embodiments, the petroleum
recovery medium described herein may be useful as a drilling fluid
or as a component thereof. In embodiments, the systems and methods
described herein may be useful for environmental remediation or for
recovery of petroleum from alternative sources, such as oil/tar
sands.
[0032] As an example, modified lignins and formulations thereof may
be useful for enhanced oil recovery, for environmental remediation
and for the recovery of petroleum from alternative sources, such as
oil/tar sands. Lignin may be modified, such as by the methods
disclosed herein, to be compatible with a wide variety of
hydrocarbons found in oil reservoirs. Lignins modified in
accordance with these systems and methods may allow for an
emulsion, such as a stable, low viscosity emulsion, to form when
such modified lignins are exposed to oil-laden materials such as
oil/tar sands, oil drilling waste and the like. The emulsion formed
with these modified lignins may be destabilized at will, creating
an easily recoverable, or separable, petroleum base. The recovery
of mixtures of the highly aromatic and long-chain aliphatic
hydrocarbons such as those found in heavy crude oil and bitumen may
be termed petroleum recovery.
[0033] In embodiments, lignins may be used to provide the
hydrophobic region of a surfactant. Lignin is a natural polymer
which can be isolated from wood and wood products and is
characterized by a hydrophobic backbone and hydroxyl groups, useful
for further modification. Lignin and oxidized lignin are waste
products from the paper industry. Oxidized lignin is described, for
example, in U.S. Pat. No. 4,790,382 and is characterized by a
plurality of hydroxyl groups which can be conveniently reacted.
Similarly, kraft lignins, such as indulins, including Indulin AT,
can be used to produce the petroleum recovery media of the
invention. For example, the hydroxyl groups of such lignins can be
reacted with an anhydride, such as succinic anhydride, and similar
compounds to form a carboxylic acid-substituted lignin, by a ring
opening reaction.
[0034] Lignin is a naturally-occurring polymer comprised of
aliphatic and aromatic portions with alcohol functionality
interspersed. Lignin polymers incorporate three monolignol
monomers, methoxylated to various degrees: p-coumaryl alcohol,
coniferyl alcohol, and sinapyl alcohol. These are incorporated into
lignin in the form of the phenylpropanoids, p-hydroxyphenyl,
guaiacyl, and syringal respectively. The systems and methods
disclosed herein describe how naturally-occurring (i.e., native)
and unnatural or modified lignin may be modified through
functionalization of the resident alcohol moieties to alter the
properties of the polymer, so that it may be adapted for petroleum
recovery. Such a functionalized lignin may be termed a "modified
lignin." The word "lignin", as used herein is intended to include
natural and non-natural lignins which possess a plurality of lignin
monomers and is intended to embrace lignin, kraft lignin, lignin
isolated from bagasse and pulp, oxidized lignin, alkylated lignin,
demethoxylated lignin, lignin oligomers, and the like.
[0035] Because lignin's chemical structure has similarity to the
aromatic compounds found abundantly in heavy crude and tar sand,
its modification and use as a tunable surfactant may be
particularly effective in emulsifying such materials in petroleum
recovery, for example as compared with generic surfactants such as
sodium dodecyl sulfate (SDS) or ordinary soaps based on aliphatic
tails. Other hydrophobic backbones which can be used to create the
surfactants of the invention include complex aromatic hydrocarbon
structures, such as polymerized tannins. In alternative
embodiments, polysaccharides, such as cellulose can be used.
Hydroxylated polystyrenes can be used as well.
[0036] In embodiments, adding a reactive agent such as succinic
anhydride or alkylated succinic anhydride to a native lignin or
other lignin may produce a modified lignin of the invention.
Alkylated succinic anhydride is commonly used in the paper industry
as a sizing agent. The alkyl additions are long chain hydrocarbons
typically containing 16-18 carbon atoms. However, alkylated
succinic acids having alkyl side chains having more than 1 carbon
atom, such as 1 to 30 carbon atoms can be used as well. Such alkyl
groups are defined herein to include straight chain, branched
cahain or cyclized alkyls as well as saturated and unsaturated
alkyls. Examples of alkylated succinic anhydride include EKA ASA
200.RTM. (a mixture of C16 and C18 ASA) and EKA ASA 210.RTM. (a C18
ASA). Addition of an anhydride, such as a succinic anhydride or
alkylated succinic anhydride to the resident alcohol groups result
in new ester linkages and the formation of carboxylic acids via a
ring opening mechanism. With the newly added carboxylic acid
functionality, the modified lignin may obtain a particularly
advantageous property: such modified lignins may be mixed with oil
to form an emulsion that can be separated simply by the addition of
a small amount of acid. In embodiments, adding acid to the
oil-lignin emulsion removes the charge on the acid groups of the
modified lignin, producing ionic destabilization that leads to
rapid de-emulsification. In embodiments, the de-emulsification
process can be measured in minutes, rather than weeks or even
months without added acid.
[0037] In embodiments, addition of alkylated succinic anhydride to
the resident alcohol groups in lignins may result in a new ester
linkage and a carboxylic acid via a ring opening mechanism. With
the newly added carboxylic acid functionality, the lignin becomes
more water soluble. The incorporation of the alkane functionalities
also imbues the compound with enhanced compatibility with lower
molecular weight alkanes also present within the bitumen. By
varying the composition of these additions, lignin can be adapted
for a wide variety of bitumen compositions and inorganic
components.
[0038] In other embodiments, the hydroxyl group resident on the
hydrophobic polymer, or lignin, can be reacted with a dicarboxylic
acid, such as maleic acid, or activated esters or anhydrides
thereof to form a carboxylic acid substituted lignin. For example,
the anhydride derived from many acids can be utilized, such as
adipic acid. Further, activated esters can be used in place of the
anhydride. Other examples will be apparent to those of ordinary
skill in the art.
[0039] In yet other embodiments, polymers and copolymers
characterized by functionalities with an affinity for aromatic fuel
compounds, functionalities with an affinity fuel compounds and
ionizable moieties can be used. For example, carboxylic acid
containing polymers such as pectin or alginate, and the like, and
synthesized polymers such as polyacrylic or methacrylic acid homo
or co-polymers.
[0040] The degree of functionalization of the lignin (i.e., the
percentage of hydroxyl groups that are reacted to present an ionic
moiety) can be between 50% and 100%, preferably between 80% and
100% on a molar basis of the hydroxyl groups found on native
lignins or a kraft lignin, such as INDULIN AT.RTM..
[0041] Where the ionizable functional group is a cation or amine,
the group can be attached to the hydrophobic backbone by chemical
methods generally known in the art. For example, the amine could be
added to a lignin via a coupling agent, such as silane or diepoxide
with a second subsequent reaction with a diamine or polyamine.
[0042] In other embodiments, lignin (oxidized or native) may be
treated by chemically reacting it with reagents to tune the
hydrophilicity to present alcohol groups. Examples of such reagents
include hydrophilic molecules, or hydrophilic polymers, such as
poly(ethylene glycol) (PEG) or polypropylene glycol) (PPO) and
combinations thereof. In a preferred embodiment, the hydrophilic
polymer can have a molecular weight between 700 and 2500 g/mol
Addition of PEG or PPO (with or without acidification) can be
useful in stabilization of the product in salt solutions,
particularly divalent cation salts. In this embodiment, the amount
of polymer to lignin is preferably added in an amount between 25%
and 75%.
[0043] An example of a chemical reaction includes:
##STR00001##
[0044] Other embodiments may include the chemical reaction of an
inert component to prevent the compound from adsorbing or
attracting to other materials within the oil formation, such as the
rock. In this embodiment, silicones, siloxanes, such as
poly(dimethylsiloxane) (PDMS), perfluorinated polymers (such as
TEFLON.RTM.), polystyrenes or other hydrophobic polymers to
increase the hydrophobicity of the lignin surfactant. Increasing
the hydrophobicity of the surfactant can result in the reduction of
surfactant loss within an oil formation comprising hydrophilic rock
or geologies. Thus, grafting such hydrophobic polymers, such as
PDMS, onto the lignin structure can be done, for example, to change
the interaction of the surfactant with various petroleum and rock
variations. The selection of the hydrophobic polymer and the amount
thereof to be grafted can be determined empirically to adapt the
surfactant to geologies that demonstrate high retention of the
surfactant. By adding these chains, adsorption can be limited and
the active concentration of surfactant to remain high. For example,
PDMS can preferably be added to the lignin polymer in an amount
between about 0 and 25% by weight.
[0045] It is desirable to control the molecular weight of the
compound. Molecular weight ranges are preferably between about 500
and 3000, preferably about 1000MW.
[0046] As described herein, the modified lignins may offer a basis
for emulsification of residual petroleum in spent oil wells, or for
emulsification of highly aromatic and aliphatic hydrocarbons such
as those found in heavy crude oil and bitumen that exist, for
example, in oil/tar sands, or for emulsification used as a
technique for cleaning oil-laden debris. Each of these uses for the
modified lignins, described in more detail herein, represents an
example of petroleum recovery.
[0047] In embodiments, the petroleum recovery medium comprises a
compound which acts as a surfactant that can solubilize oil
resident in oil reservoirs and facilitate its removal at a first
pH. After the oil has been recovered and transported to the
ultimate collection site in an emulsion formed using such a
surfactant, the pH of the solution may be altered, e.g., lowered,
to disrupt the emulsion. This technology may permit the oil and
water phase in the emulsion to separate and form a stratified
system in a holding tank from which oil may be recovered. Using
this technology, the surfactant may remain in the oil stock
fraction. This is particularly preferred where the surfactant is
free of nitrogen or sulfur. Due to the similar characteristics
between the chemistry of the surfactant and the petroleum, the
surfactant may be processed alongside with little hindrance to the
upgrading procedures.
[0048] In embodiments, modified lignin solutions can also be
formulated with other small molecule or polymeric surfactants and
cosolvents to facilitate adaptation to various petroleum grades.
These can be added to increase miscibility and emulsion formation
or as additives for viscosity modifiers. Other additions can
include hydrophobic polymers such as PDMS and the like that can
tailor the properties according to the resident geology. Other
modifications and applications of modified lignin solutions and
formulations disclosed herein should be readily apparent to skilled
artisans, using no more than routine experimentation.
Petroleum Recovery Technology
[0049] In embodiments, the systems and methods described herein may
provide modified and unmodified lignins as extraction agents for
enhanced oil recovery or for recovering petroleum from mixed grade
oil sands. As used herein, the terms "oil sands" or "tar sands"
refer to petroleum resources comprising mixtures of sand or clay,
water, and petroleum, usually dense petroleum or bitumen. "Mixed
grade" refers to oil sands that contain both high-grade oil sands
with high bitumen content and low content of inorganic materials,
and low-grade oil sands with low bitumen content and high content
of inorganic materials.
[0050] In embodiments, modified lignins may be useful in
combination with other processes for enhanced oil recovery (EOR).
By injecting a portion, or "slug", of a waterborne lignin
surfactant into an underground rock formation, residual oil can be
stripped from the rock due to the decreased surface tension
afforded by the surfactant, and propagated to a production well via
subsequent water slugs. The surfactant slug may be comprised of
some weight fraction of modified lignin, for example between 100
and 10,000 ppm concentration. It is generally desirable to minimize
the amount of surfactant added to achieve an emulsion while
minimizing cost. The term "effective amount," as used herein is
defined to mean at least the amount of compound, or surfactant,
required to achieve an emulsion at the conditions of use during oil
extraction and can be empirically determined for each oil recovery
site and application. Typically, the amount of surfactant required
will be less than 1% by weight of the water slug, usually between
100 and 10,000 ppm, preferably between 5,000 and 10,000 ppm.
Additionally, other additives known in the art can be added as
viscosity modifiers and/or corrosion inhibitors, and the like.
[0051] Though it is understood that the majority (80-90%) of the
oil will be produced ahead of the surfactant slug, a portion
remains as a mixture with the surfactant. Technology utilizing
surfactant slugs is described in L. W. Lake, Enhanced Oil Recovery,
(Prentice Hall, 1989), the contents of which are included herein by
reference. Rather than discarding this fraction or risk
contamination of downstream refining equipment, an emulsion formed
with modified lignins and other compounds described herein as
surfactants can be rapidly separated by modifying pH, such as by
the addition of a protic acid, to break the emulsion and create a
preliminary petroleum purification. Examples of suitable strong
protic acids that can be used in breaking the emulsion or
separating the aqueous and oil phases includes, but is not limited
to, hydrochloric and sulfuric acids.
[0052] In embodiments, the novel surfactants, or modified lignins,
may be useful for recovering petroleum in a useful form from mixed
grades of oil sands, as well as from high-grade oil sands. Using a
process aid based on a modified lignin, these oil sands may be made
more productive. Addition of hydrophilic moieties to the aliphatic
and phenolic alcohol functional groups present on the polymer can
give it increased water solubility. The base lignin, structurally
similar to bitumen, helps to strip the petroleum product from
inorganic materials, such as those found in oil sands
applications.
[0053] In embodiments, the novel surfactants, or modified lignins,
modified by the methods disclosed herein may be used to strip
tar/oil sands of their residual oil. Using these compositions and
methods, petroleum residing on the bituminous ore can be recovered
as a lower viscosity water emulsion. The resulting emulsion can
then be easily transported to refining centers for further
processing, unlike concentrated bitumen. In embodiments, modified
lignins may possess a tunable phase separation property that
facilitates water removal from this mixture.
[0054] In embodiments, addition of alkylated succinic anhydride to
the resident alcohol groups in lignins may result in a new ester
linkage and a carboxylic acid via a ring opening mechanism. With
the newly added carboxylic acid functionality, the lignin becomes
more water soluble. The incorporation of more alkane
functionalities also imbues the polymer with enhanced compatibility
with lower molecular weight alkanes also present within the
bitumen. By varying the composition of these additions, lignin can
be adapted for a wide variety of bitumen compositions and inorganic
components.
[0055] In embodiments, modified or unmodified lignin solutions can
also be formulated with other small molecule or polymeric
surfactants and cosolvents to facilitate adaptation to various
bitumen grades. These can be added to increase miscibility and
emulsion formation or as additives for viscosity modifiers. By
varying the composition of these additions, lignin can be adapted
for a wide variety of bitumen compositions and inorganic
components. In embodiments, modified or unmodified lignin solutions
can also be formulated with other small molecule or polymeric
surfactants and cosolvents to facilitate adaptation to various
bitumen grades. These can be added to increase miscibility and
emulsion formation or as additives for viscosity modifiers.
Environmental Remediation
[0056] In embodiments, systems and methods are provided herein for
producing formulations having applications in the field of oil
extraction, both for well development operations such as drilling
operations, work-over operations or completion operations and for
oilfield production proper. As described herein, the novel
surfactants, or modified lignins, modified for use in environmental
remediation and oil recovery may allow for a stable, low viscosity
emulsion that can be destabilized at will, creating an easily
recoverable petroleum base. In embodiments, the novel surfactants,
or modified lignins, may be useful for cleaning oil-laden debris or
for recovering emulsified petroleum products.
[0057] In embodiments, the novel surfactants, or modified lignins,
may be used alone or with other components in a solution used to
extract the oil that coats the debris produced during the drilling
process. Properties of the novel surfactants, or modified lignins,
may include increased hydrocarbon solubility and the ability to
emulsify hydrocarbons in aqueous solution. Certain modifications as
disclosed herein may be particularly advantageous for recovering
oil from oil drilling debris and the like, for example, by means of
pH adjustment inducing phase separation of the emulsion. As
described herein, tunable induction of phase separation may be
advantageously substituted for present, more expensive treatment
methods such as dessication and other isolation procedures.
EXAMPLES
Example 1
[0058] Indulin AT is used as the lignin source. Indulin AT is a
purified form of the lignin obtained from the black liquor in the
Kraft pulping process. Here, Indulin AT (5.0 g) is suspended in 150
ml of acetone. Alkylated succinic anhydride in the form of Eka SA
210 (25.0 g) is added to the suspension. The reaction is performed
in a bomb and heated to 70.degree. C. over the course of 48 hours.
The resulting material can be diluted with alkaline water and used
as a suitable surfactant for stripping oil from debris produced as
a byproduct of drilling. Oil coated debris is then exposed to the
brown aqueous dispersion in a 1:1 weight ratio for several seconds
with agitation. Afterwards, the liquid portion is decanted from the
now clean debris. Acid is then added to the separated liquid to
induce phase separation.
Example 2
[0059] Indulin AT (5.0 g) is mixed with 10.0 g Eka SA 210 in a bomb
filled with 150 ml of acetone. The mixture is heated to 70.degree.
C. over 48 hours, and the recovered product is diluted with
alkaline water for an active product. Oil coated debris is then
exposed to the brown aqueous dispersion in a 1:1 weight ratio for
several seconds with agitation. Afterwards, the liquid portion is
decanted from the now clean debris. Acid is then added to the
separated liquid to induce phase separation.
Example 3
[0060] Indulin AT (5.0 g) is mixed with 5.0 g Eka SA 210 in a bomb
filled with acetone. The mixture is heated to 70.degree. C. over 48
hours. The resulting mixture is filtered; the supernatant is
recovered and diluted with alkaline water to create an active
product. Oil coated debris is then exposed to the brown aqueous
dispersion in a 1:1 weight ratio for several seconds with
agitation. Afterwards, the liquid portion is decanted from the now
clean debris. Acid is then added to the separated liquid to induce
phase separation. The debris can then be tested for residual oil
content.
Example 4
[0061] Indulin AT (5.0 g) is mixed with 4.0 g Eka SA 210 in a bomb
filled with 150 ml of acetone. The mixture is heated to 70.degree.
C. over 48 hours. The resulting mixture is filtered; the
supernatant is recovered and diluted with alkaline water to create
an active product. Oil coated debris is then exposed to the brown
aqueous dispersion in a 1:1 weight ratio for several seconds with
agitation. Afterwards, the liquid portion is decanted from the now
clean debris. Acid is then added to the separated liquid to induce
phase separation. The debris can then be tested for residual oil
content.
Example 5
[0062] Indulin AT (5.0 g) is mixed with 3.0 g Eka SA 210 in a bomb
filled with 150 ml of acetone. The mixture is heated to 70.degree.
C. over 48 hours. The resulting mixture is filtered; the
supernatant is recovered and diluted with alkaline water to create
an active product. Oil coated debris is then exposed to the brown
aqueous dispersion in a 1:1 weight ratio for several seconds with
agitation. Afterwards, the liquid portion is decanted from the now
clean debris. Acid is then added to the separated liquid to induce
phase separation. The debris can then be tested for residual oil
content.
Example 6
[0063] Indulin AT (5.0 g) is mixed with 2.5 g Eka SA 210 in a bomb
filled with 150 ml of acetone. The mixture is heated to 70.degree.
C. over 48 hours. The resulting mixture is filtered; the
supernatant is recovered and diluted with alkaline water to create
an active product. Oil coated debris is then exposed to the brown
aqueous dispersion in a 1:1 weight ratio for several seconds with
agitation. Afterwards, the liquid portion is decanted from the now
clean debris. Acid is then added to the separated liquid to induce
phase separation. The debris can then be tested for residual oil
content.
Example 7
[0064] Indulin AT (5.0 g) is mixed with 1.0 g Eka SA 210 and 3.0 g
succinic anhydride in a bomb filled with 150 ml of acetone. The
mixture is heated to 70.degree. C. over 48 hours. The resulting
mixture is filtered; the supernatant is recovered and diluted with
alkaline water to create an active product. Oil coated debris is
then exposed to the brown aqueous dispersion in a 1:1 weight ratio
for several seconds with agitation. Afterwards, the liquid portion
is decanted from the now clean debris. Acid is then added to the
separated liquid to induce phase separation. The debris can then be
tested for residual oil content.
Example 8
[0065] Indulin AT (5.0 g) is mixed with 2.0 g Eka SA 210 and 2.0 g
succinic anhydride in a bomb filled with 150 ml of acetone. The
mixture is heated to 70.degree. C. over 48 hours. The resulting
mixture is filtered; the supernatant is recovered and diluted with
alkaline water to create an active product. Oil coated debris is
then exposed to the brown aqueous dispersion in a 1:1 weight ratio
for several seconds with agitation. Afterwards, the liquid portion
is decanted from the now clean debris. Acid is then added to the
separated liquid to induce phase separation. The debris can then be
tested for residual oil content.
Example 9
[0066] Indulin AT (5.0 g) is mixed with 3.0 g Eka SA 210 and 1.0 g
succinic anhydride in a bomb filled with 150 ml of acetone. The
mixture is heated to 70.degree. C. over 48 hours. The resulting
mixture is filtered; the supernatant is recovered and diluted with
alkaline water to create an active product. Oil coated debris is
then exposed to the brown aqueous dispersion in a 1:1 weight ratio
for several seconds with agitation. Afterwards, the liquid portion
is decanted from the now clean debris. Acid is then added to the
separated liquid to induce phase separation. The debris can then be
tested for residual oil content.
Example 10
[0067] Indulin AT (5.0 g) is mixed with 4.0 g Eka SA 210 and 1.0 g
polyethylene glycol diglycidyl ether in a bomb filled with 150 ml
of acetone. The mixture is heated to 70.degree. C. over 48 hours.
The resulting mixture is filtered; the supernatant is recovered and
diluted with alkaline water to create an active product. Oil coated
debris is then exposed to the brown aqueous dispersion in a 1:1
weight ratio for several seconds with agitation. Afterwards, the
liquid portion is decanted from the now clean debris. Acid is then
added to the separated liquid to induce phase separation. The
debris can then be tested for residual oil content.
Example 11
[0068] Indulin AT (5.0 g) is mixed with 3.0 g Eka SA 210 and 1.0 g
polypropylene oxide diglycidyl ether in a bomb filled with 150 ml
of acetone. The mixture is heated to 70.degree. C. over 48 hours.
The resulting mixture is filtered; the supernatant is recovered and
diluted with alkaline water to create an active product. Oil coated
debris is then exposed to the brown aqueous dispersion in a 1:1
weight ratio for several seconds with agitation. Afterwards, the
liquid portion is decanted from the now clean debris. Acid is then
added to the separated liquid to induce phase separation.
Example 12
[0069] Lignin derivatives based on Indulin AT were prepared
following the procedures listed in the previous examples for each
derivative described below. Each lignin derivative was dissolved in
water with minimal addition of concentrated sodium hydroxide
solution (6M, about 1 ml) at a 1 wt % concentration. The resulting
surfactant solution was then placed in a container with oil sands
(4 g) to create a slurry with 10-30% solid content by weight.
Aeration was performed on the slurry along with mechanical
stirring. The bubbles created were allowed to flow in an exterior
dish for collection of any bitumen carried by the bubbles. After
several minutes of aeration and agitation, the sample dish was then
drained of fluids, and the resulting sand was analyzed for residual
bitumen content via combustion. The following results were
obtained:
Sample 1: Using a surfactant with the composition of Indulin AT
modified with 20 weight percent poly(dimethylsiloxane) and 80
weight percent Eka SA 210 alkylated succinic anhydride to extract
bitumen from a low-grade oil sand sample (4 g):
[0070] 2.78 g remaining solids (8% bitumen content)
[0071] 0.59 g clean bitumen removed.
Sample 2: Using a surfactant with the composition of Indulin AT
modified with 20 weight percent poly(dimethylsiloxane) and 80
weight percent Eka SA 210 alkylated succinic anhydride to extract
bitumen form a high-grade oil sand sample (4 g):
[0072] 3.229 g remaining solids (9% bitumen content)
[0073] 0.542 g clean bitumen removed.
Sample 3: Using a surfactant with the composition of Indulin AT
modified with 20 weight percent polypropylene oxide) and 80 weight
percent Eka SA 210 alkylated succinic anhydride to extract bitumen
form a low-grade oil sand sample (4 g):
[0074] 2.7602 g remaining solids (4% bitumen content)
[0075] 0.6786 g clean bitumen removed.
[0076] For comparison, the oil sands sample received was
approximately 10% bitumen content. A high bitumen content sample
obtained from a different source was approximately 15% bitumen
content.
[0077] Each patent, patent application and publication referenced
or discussed above is hereby incorporated by reference in its
entirety.
EQUIVALENTS
[0078] While specific embodiments of the subject invention have
been discussed, the above specification is illustrative and not
restrictive. Many variations of the invention will become apparent
to those skilled in the art upon review of this specification. The
full scope of the invention should be determined by reference to
the claims, along with their full scope of equivalents, and the
specification, along with such variations.
[0079] Unless otherwise indicated, all numbers expressing
quantities of ingredients, reaction conditions, and so forth used
in the specification 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 specification and attached claims are approximations that may
vary depending upon the desired properties sought to be obtained by
the present invention.
[0080] While this invention has been particularly shown and
described with references to preferred embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
scope of the invention encompassed by the appended claims.
* * * * *