U.S. patent application number 10/797655 was filed with the patent office on 2005-09-15 for oil recovery method using alkali and alkylaryl sulfonate surfactants derived from broad distribution alpha-olefins.
Invention is credited to Berger, Christie H., Berger, Paul D..
Application Number | 20050199395 10/797655 |
Document ID | / |
Family ID | 34920101 |
Filed Date | 2005-09-15 |
United States Patent
Application |
20050199395 |
Kind Code |
A1 |
Berger, Paul D. ; et
al. |
September 15, 2005 |
Oil recovery method using alkali and alkylaryl sulfonate
surfactants derived from broad distribution alpha-olefins
Abstract
An oil recovery process is disclosed which uses an alkali(s) and
a particular class of alkylaryl sulfonate surfactants. The
surfactants are derived from an alpha-olefin stream having a broad
distribution of even carbon numbers ranging from 12 to 28 or more.
The olefin stream is reacted with aromatic feedstock, such as
benzene, toluene, xylene, ethylbenzene, or a mixture thereof to
form alkylates, and then reacted with SO3 to form sulfonic acids.
Alternatively, the surfactant can be formed by first reacting an
alpha-olefin stream having a broad distribution of carbon numbers
ranging from 12 to 28 or more with SO3 to form the olefin sulfonic
acid that is subsequently used to alkylate an aromatic feedstock.
The use of alkali(s) and broad distribution alpha-olefins sulfonate
based surfactant has the improvements of requiring ultra-low
surfactant concentrations and providing ultra-low interfacial
tensions over a wide range of alkali concentrations with crude
oils, especially waxy crude oil, having a broad distribution of
carbon numbers.
Inventors: |
Berger, Paul D.; (Sugar
Land, TX) ; Berger, Christie H.; (Sugar Land,
TX) |
Correspondence
Address: |
OIL CHEM TECHNOLOGIES
ATTN: PAUL BERGER
13013 JESS PIRTLE BLVD.
SUGAR LAND
TX
77478
US
|
Family ID: |
34920101 |
Appl. No.: |
10/797655 |
Filed: |
March 10, 2004 |
Current U.S.
Class: |
166/270.1 ;
166/403 |
Current CPC
Class: |
C09K 8/584 20130101 |
Class at
Publication: |
166/270.1 ;
166/403 |
International
Class: |
E21B 043/22 |
Claims
What is claimed is:
1. A method of recovering crude oil from a subterranean hydrocarbon
containing formation which comprises (a) injecting into said
formation through an injection well an aqueous solution containing
an effective amount of one or more alkali(s) along with an
effective amount of alkylaryl sulfonate surfactant made by
alkylating and sulfonating aromatic compounds and an alpha-olefin
stream having a broad distribution in olefin carbon numbers, the
olefin stream is the carbon chain C.sub.10 bottoms of a commercial
ethylene synthesis alpha-olefin reactor and comprises C.sub.10+
through C.sub.30+ carbon chain fractions, and wherein the aromatic
compound is selected from the group consisting of benzene, toluene,
xylene, ethyl benzene, or mixtures thereof, and then neutralizing
the resulting alkylaryl sulfonic acid, and (b) displacing said
solution into the formation to recover hydrocarbons from a
production well.
2. The method of claim 1 wherein said alkali is one or more
selected from the group mono valent hydroxide, mono valent
carbonate, mono valent silicate.
3. The method according to claim 1 wherein the alkali is selected
from the group sodium hydroxide, sodium carbonate, sodium
silicate.
4. The method of claim 1 where the alkali is present in amounts of
from about 0.1% by weight to about 3.0% by weight.
5. The method of claim 1 where the alkylaryl sulfonate surfactant
is present in amounts from about 0.025% by weight to about 0.5% by
weight.
6. The method of claim 1 wherein said alpha-olefin stream is a
combination of individual alpha-olefin fractions having a carbon
chain of from about C.sub.12 to about C.sub.28.
7. The method according to claim 1 wherein the aromatic compound is
o-xylene, m-xylene, p-xylene or mixtures thereof and wherein the
injection wells and production wells are selected from the group
consisting of the same well, different wells or combinations
thereof.
8. The method of claim 1 wherein alkylation of the aromatic
compounds by the alpha-olefin stream having a broad distribution in
olefin carbon numbers is conducted with AlCl.sub.3 or HF
catalyst.
9. The method of claim 1 wherein alkylation of the aromatic
compounds is conducted using the olefin sulfonic acids from the
sulfonation of an alpha-olefin stream having a broad distribution
in olefin carbon numbers.
10. The method of claim 1 where the neutralization is carried out
using NaOH.
11. An alkali and alkylaryl sulfonate surfactant composition for
enhanced oil recovery giving the improvement ultra-low interfacial
tensions over a wide range of alkali(s) concentrations, comprising
one or more alkali(s) along with an alkylaryl sulfonate wherein the
alkyl chain includes C.sub.12 to C.sub.30+ carbon chain lengths and
wherein the carbon chain is straight, branched or mixtures thereof,
and wherein the aryl group is selected from the group benzene,
toluene, xylene, ethyl benzene, or mixtures thereof.
12. The composition of claim 11 wherein said alkali is one or more
selected from the group mono valent hydroxide, mono valent
carbonate, mono valent silicate.
13. The composition according to claim 11 wherein the alkali is
selected from the group sodium hydroxide, sodium carbonate, sodium
silicate.
14. The composition according to claim 11 wherein the aryl group is
o-xylene, m-xylene, p-xylene, or mixtures thereof.
15. The composition of claim 11 where the alkali is present in
amounts of from about 0.1% by weight to about 3.0% by weight.
16. The composition of claim 11 where the alkylaryl sulfonate
surfactant is present in amounts from about 0.025% by weight to
about 0.5% by weight.
17. The composition of claim 11 wherein said alkyl chain is one
having a carbon chain of from about C.sub.12 to about C.sub.28.
Description
FIELD OF INVENTION
[0001] The present invention is directed to enhanced oil recovery
(EOR). More specifically, the present invention is directed to
enhanced oil recovery of crude oil using a mixture of alkali(s) and
alkylaryl sulfonate surfactant derived from broad distribution
alpha-olefins.
BACKGROUND OF THE INVENTION
[0002] This invention is an improvement over U.S. Pat. No.
6,269,881 and much of the background material is drawn from this
reference and all references included in U.S. Pat. No. 6,269,881
are included herein.
[0003] Alkylaryl sulfonates with narrow distribution carbon chains
have long been recognized as promising surfactants for EOR. They
can be manufactured in fairly large quantities and can generate
adequate phase behavior and low interfacial tensions (IFT) with
oils under favorable conditions. However, pure alkylaryl sulfonates
such as hexadecyl benzene sulfonate or those having a narrow
distribution carbon chains, cannot generate adequate phase behavior
and low interfacial tension with a wide range of crude oils
especially when dealing with heavier crude oils, particularly those
with a high wax content. They must be used at relatively high
concentrations and they do not form normal phase behavior when
mixed with crude oil and brine of varying salinity. Furthermore,
when used together with alkali in alkali surfactant flood,
alkylaryl sulfonates with narrow distribution carbon chains are
only effective over limited ranges of alkali which is detrimental
to efficient oil recovery. Pure alkylaryl sulfonates or those with
narrow distribution carbon chains have other disadvantages. With
low oil prices, the surfactant used to recover such oil must be
cost effective. Prior methods, which use alkylaryl sulfonates with
narrow distribution of carbon chain lengths, increase the cost
because of the large quantities of unsuitable byproducts and/or the
need for more tightly controlled reaction conditions or specialized
catalysts required to manufacture such surfactants.
[0004] Alkyl aryl surfactants derived from broad distribution
alpha-olefins have recently been recognized as promising for
enhanced oil recovery by surfactant floods as noted in U.S. Pat.
No. 6,269,881. However, use of the broad distribution alpha-olefins
surfactants generally requires 0.5% to 3.0% and most preferably 1.0
to 1.5% as noted in U.S. Pat. No. 6,269,881. The higher
concentration of the surfactant and the optima salinity required
are uneconomical and unsatisfactory for a large quantity surfactant
flood. Also, Malmberg and Smith in "Improved Oil Recovery by
Surfactant and Polymer Flooding" Shah and Schechter ed., (Academic
press 1977), pp. 282 found that adsorption increases with
increasing average equivalent weight of sulfonates so that the
higher molecular weight fractions of these broad distribution
surfactants are subject to selective adsorption.
[0005] Thus it would be highly desirable to have a recovery method
and composition useful for recovering crude oil that employs
ingredients that are readily available in large quantities at
reasonable cost. Also it would be desirable to have a composition
that includes a broad spectrum of carbon chain lengths so
substantially complete production runs can be used. Also it would
be desirable if such compositions could be rendered effective at
low surfactant concentrations and not be subject to chromatographic
separation due to selective adsorption while propagating through
the oil containing reservoir formation because of the increasing
average equivalent weight of sulfonates. Also it would be desirable
to have a composition that is not dependent on an optimum salinity
for optimum performance. Also it would be desirable to have a
composition that is effective over wide ranges of alkali.
SUMMARY OF THE INVENTION
[0006] This invention provides an improvement over the closest
existing art described in U.S. Pat. No. 6,269,881 and also provides
other benefits that are not obvious to the ordinary skilled artisan
which arise from the inclusion of alkali(s) with the surfactant
derived from broad distribution alpha-olefins in the method of
recovering oil from subterranean hydrocarbon containing formations
and in the composition of enhanced oil recovery to displace said
composition through the subterranean formation. The method is
especially useful when the reservoir oil has higher wax content.
The present invention includes a method of recovering crude oil
from a subterranean hydrocarbon containing formation which
comprises (a) injecting into said formation through an injection
well an aqueous solution containing an effective amount of one or
more alkali(s) along with an effective amount of alkylaryl
sulfonate surfactant made by alkylating and sulfonating aromatic
compounds and an alpha-olefin stream having a broad distribution in
olefin carbon numbers, the olefin stream is the carbon chain
C.sub.10 bottoms of a commercial ethylene synthesis alpha-olefin
reactor and comprises C.sub.10+ through C.sub.30+ carbon chain
fractions, and wherein the aromatic compound is selected from the
group consisting of benzene, toluene, xylene, ethyl benzene, or
mixtures thereof, and then neutralizing the resulting alkylaryl
sulfonic acid, and (b) displacing said solution into the formation
to recover hydrocarbons from a production well.
[0007] The present invention also includes an alkali(s) and
alkylaryl sulfonate surfactant composition for enhanced oil
recovery giving the improvements of requiring ultra-low surfactant
concentration and providing ultra-low interfacial tensions over a
wide range of alkali(s) concentrations. Said composition comprises
one or more alkali(s) along with an alkylaryl sulfonate wherein the
alkyl chain includes C.sub.12 to C.sub.30+ carbon chain lengths and
wherein the carbon chain is straight, branched or mixtures thereof,
and wherein the aryl group is selected from the group benzene,
toluene, xylene, ethyl benzene, or mixtures thereof. The alkali(s)
that may be used include any inorganic or organic salt, or the
mixture thereof, that is capable of increasing the pH of the
injection solution above 9.
BRIEF DESCRIPTION OF THE FIGURES
[0008] FIG. 1 shows the interfacial tension values obtained with
various concentrations of NaOH and the three examples of alklaryl
sulfonates described in this patent.
[0009] FIG. 1 shows the interfacial tension values obtained with
various concentrations of one of the examples from this patent,
OXS-1228, when no NaOH is added.
DETAILED DESCRIPTION OF THE INVENTION
[0010] The present invention is the inclusion of alkali(s) along
with alkylaryl sulfonates derived from a broad distribution of
alpha-olefins greater than C10 to C58 or more, or preferably the
entire C10 bottoms fraction, i.e., greater than C10 of an
alpha-olefin process. Suitable ranges are C12 to C40 preferably
ranges such as C10 to C32; C12 to C28; and C10 to C24. In contrast,
conventionally used alkylaryl sulfonates generally focus on a
narrow range of olefin carbon numbers, such as C12 xylene
sulfonate, C12 benzene sulfonate, C16 xylene sulfonate, C18 toluene
sulfonate, and C20-24 toluene sulfonate. In these cases, other
carbon chain lengths made during the reaction must be separated
out. This adds to the cost of the specifically used product. In
commercial applications of alkali surfactant floods, the quantity
of surfactant required is huge, often exceeding 100 million pounds
lbs. If only a narrow fraction of the alpha-olefins are used to
make the surfactant, the required olefin plant capacity would
exceed a few billion pounds, which is not presently available.
While one can build a new plant to meet the demand of the
surfactant flood, the unused olefin fractions cannot be readily
used for other purposes and, therefore, must be accounted for in
the cost of the olefin feedstocks for the surfactant. Thus the
present invention of the EOR composition and process of recovering
oil using surfactant derived from broad distribution alpha-olefins
along with alkali(s) permits better use of the whole spectrum of an
alpha-olefin plant's products. Since the current alpha-olefin
market is largely driven by the demand in C10 and lower fractions
use in plastic production such as polyethylene and/or
polypropylene, the use of C10 bottoms (i.e., C12 and higher
fractions) in the present invention does not pose a conflict or
tradeoff. It actually provides for a more synergistic use of the
plants total output. In fact, taking the entire C10 bottoms, i.e.,
C12 and higher, would eliminate many costly fractionation steps,
thus further lowering the cost of the alpha-olefin feedstock for
the surfactant.
[0011] The surfactant derived from broad distribution alpha-olefins
is used in an aqueous injection solution in combination with
alkali(s), and optionally a conventional cosurfactant/solvent and a
polymer to increase the recovery of crude oil from a subterranean
formation. The most preferred broad distribution alkylaryl
sulfonate is the sodium salt of xylene sulfonic acid. Alkalis that
may be used include any inorganic or organic compounds or mixtures
of two or more that is capable of increasing the pH of the
injection solution above pH 9. These include, but are not limited
to, sodium, potassium, or ammonium hydroxide; sodium, potassium, or
ammonium carbonate; sodium, potassium, or ammonium silicate, as
well as any other compounds that give a pH in excess of 9 in the
injection solution. The most preferred alkali is sodium hydroxide
or sodium carbonate.
[0012] Broad distribution alkyl aryl sulfonate EOR surfactant can
be prepared by the process described in U.S. Pat. No. 6,269,881
wherein the alkylaryl sulfonate preparation involves three steps:
three steps: alkylation, sulfonation and neutralization.
[0013] Similar broad distribution alkylaryl sulfonates can be
prepared by the process described in U.S. Pat. No. 6,043,391 where
the broad distribution alpha-olefin is first sulfonated in a thin
film reactor with SO3/Air to form the olefin sulfonic acid. This
olefin sulfonic acid is then reacted with a suitable aromatic
compound such as benzene, toluene, xylene, or mixtures thereof, to
form the arylalkyl sulfonic acid that is then neutralized with a
strong base such as sodium hydroxide to form the sulfonate. It
should be noted that the synthesis procedure described in U.S. Pat.
No. 6,043,391 is the reverse of the procedure described in U.S.
Pat. No. 6,269,881. In U.S. Pat. No. 6,269,881, the aromatic
compound is first alkylated with the broad distribution
alpha-olefins and then the resulting alkylate is sulfonated to form
an alkylaryl sulfonic acid. In the U.S. Pat. No. 6,043,391
procedure the broad distribution alpha-olefins are first sulfonated
and the resulting alpha-olefin sulfonic acid is used to alkylate
the aromatic compound. One advantage of the process described in
U.S. Pat. No. 6,043,391 is that the need for a separate alkylation
plant is eliminated. This results in considerable up-front savings
as well as elimination of on-going operational cost associated with
an alkylation plant.
[0014] The use of xylene as the aromatic compound for alkylation is
especially preferred because of its higher boiling point that
allows it to be handled without pressure during alkylation and/or
sulfoalkylation. While not described here, one can certainly use a
mixture of benzene, ethylbenzene, toluene, and xylene of various
fractions or any of these aromatic compounds individually to
optimize the surfactant for a specific reservoir application or to
take advantage of the aromatics market conditions.
[0015] The present invention, a composition comprising a mixture of
alkali(s) and a alkylaryl sulfonate surfactant derived from a broad
distribution of alpha-olefins, is injected into an injection well
in an effective amount to allow the recovery of oil from a
production well by lowering the IFT between trapped oil and the
injection solution. The injection well and the producing well may
be the same or different wells or a combination of both. The
concentration ranges of the present invention using the neutralized
form of the surfactant derived from the broad distribution of
alpha-olefins are from 0.025% to 0.5% by weight, preferably 0.05%
to 0.2% by weight, and most preferably 0.05% to 0.1% by weight. The
concentration ranges of alkali(s) are 0.1 to 3.0% by weight,
preferably 0.5 to 2.0% by weight and most preferably 0.5 to 1.0% by
weight. A cosurfactant/solvent may be included at approximately the
same concentration as the surfactant and is usually formulated with
the surfactant in a concentrated form that is diluted with
injection water to the appropriate final concentration at the
injection site. An alcohol or ether such as Iso-propanol,
sec-butanol or ethylene glycol monobutyl ether (EB) can be used as
the cosurfactant/solvent.
[0016] Polymers, such as those commonly employed for such purposes,
may be included to control the mobility of the injection solution.
Such polymers include, but are not limited to, xanthan gum,
partially hydrolyzed polyacrylamides and copolymers of
2-acrylamido-2-methylpropane sulfonic acid and polyacrylamide
commonly referred to as AMPS copolymer. Polymers are used in the
range of about 500 to about 2000 PPM in order to match or exceed
the reservoir oil viscosity under reservoir conditions of
temperature and pressure.
[0017] The present invention includes the addition of a composition
comprising a mixture of alkali(s) and an alkylaryl sulfonate
surfactant derived from a broad distribution of alpha-olefins into
an oil-bearing subterranean formation at concentration levels of
surfactant between 0.025% and 0.5% as opposed to U.S. Pat. No.
6,269,881 that requires 0.5% to 3.0%, thus providing a significant
cost advantage. The alkali(s) also acts synergistically with the
surfactant to give optimum performance as demonstrated by ultra-low
interfacial tensions obtained at very low surfactant
concentrations. The ultra-low IFTs are not obtainable without the
use of such alkali(s) at such low surfactant concentrations. In
addition, the alkali reduces the chromatographic separation of the
sulfonate surfactant containing a broad distribution of alkyl chain
lengths by increasing the pH of the injection water. Increasing the
pH to exceed the iso-electric point of the reservoir rock decreases
the electrical attraction that might normally occur between the
positively charged surface and the negatively charge anionic
surfactant. See for example, Baviere, "Basic Concepts on Enhanced
Oil Recovery Processes" (Elsevier 1991) pp. 147-149. The present
invention also does not require any adjustment of the injection
brine to the optimum salinity. Adjusting the injection brine to the
optimum salinity will give ultra-low IFT without the use of alkali,
however; as is commonly known to those familiar with the art, the
salinity cannot be maintained at the optimum level and will deviate
from the optimum as the solution progresses through the oil-bearing
reservoir. This is due to adsorption of electrolyte and mixing with
connate brine. Therefore a system not dependent on optimum salinity
would be desirable.
[0018] The use of alkali(s) with surfactant has been previous
described in the literature; however, the alkali surfactant
processes described in the prior art using narrow distribution
alkylaryl sulfonates work only over a narrow range of alkali where
ultra-low interfacial tensions are obtained. Even when an optimum
ratio of surfactant to alkali is introduced into the reservoir, the
ratio of the two will change as they propagate through the
reservoir. This is due to the preferential adsorption of the alkali
onto the formation causing the ratio of alkali to surfactant to
deviate from the optimum. Therefore, being able to obtain ultra-low
IFT over a wide range of alkali is very important for oil recovery
optimization. The present invention includes alkali(s) with a
surfactant derived from a broad distribution of alpha-olefins.
Unexpectedly, we have found the use of alkali(s) with surfactant
derived from broad distribution alpha-olefins gives additional
advantages heretofore not described in the art. Using alkali(s)
combined with an alkylaryl surfactant derived from broad
distribution alpha-olefins widens the range of alkali that can be
used to give ultra-low IFT suitable for oil recovery. This wide
range of alkali where ultra-low IFT is observed is not obtainable
with the surfactant made from narrow distribution carbon
ranges.
[0019] In a process similar to that described in U.S. Pat. No.
6,269,881, the C12 to C28 cut of an alpha-olefin was reacted with
mixed xylene, consisting of 90% o-xylene and the other 10% a
mixture of meta-xylene and para-xylene to form alkylates using
AlCl.sub.3 catalyst, and subsequently sulfonated with SO.sub.3.
This surfactant is designated as OXS12-28.
[0020] In another example, using the process similar to that
described in U.S. Pat. No. 6,269,881, the C16 cut of an
alpha-olefin was reacted with a mixed xylene, consisting of 90%
o-xylene and the other 10% a mixture of meta-xylene and para-xylene
to form alkylates using AlCl.sub.3 catalyst, which are subsequently
sulfonated with SO.sub.3. This surfactant is designated as
OXS16.
[0021] In another example, using the process described in U.S. Pat.
No. 6,043,391, the C12 to C28 cut of an alpha-olefin is sulfonated
with SO.sub.3 to form alpha-olefin sulfonic acids that are
subsequently reacted with a mixed xylene, consisting of 90%
o-xylene and the other 10% a mixture of meta-xylene and
para-xylene. This surfactant is designated OXS12-28-N.
[0022] The following examples compare the results using the
previously described OXS12-28, OXS16 and OSX 12-28-N. A surfactant
concentrate of each example was prepared by neutralizing the
sulfonic acid in a mixture of water and EB. The concentrate
contained 50% by weight sodium salt of the sulfonic acid, 25% by
weight EB and the remainder water. A simulated injection brine was
used containing 4500 ppm of total dissolved solids with 310 ppm of
di-valent cations. The crude oil used had a density of 0.834 gm/cc
(38.2 API Gravity) @25.degree. C.
[0023] Interfacial tensions (IFT) were measured at 45.degree. C.
using a University of Texas Model 500 spinning drop interfacial
tensiometer. FIG. 1 shows the IFT of the simulated injection brines
each containing 0.2% by weight of each of the surfactant
concentrates and various concentrations of NaOH against the crude
oil at 45.degree. C. The IFT of the three samples are in the range
of about 1.0 mN/m without the addition of NaOH. This is not
sufficient for removing oil as is commonly known to those familiar
with the art as practiced in this field, and as described by Austad
and Miller in "Surfactants-Fundamentals and Applications in the
Petroleum Industry", pp. 205-207. Here the authors discuss the
concept of capillary number and have determined that the
interfacial tension must be lowered to a value of between 0.01 to
0.001 mN/m to mobilize trapped discontinuous oil in a reservoir.
The concentration ranges of the alkali that provides adequate IFT
with the surfactant is important. A wider range means that the IFT
lowering properties of the surfactant are less sensitive to the
alkali concentrations which is very important to the oil recovery.
FIG. 1 also shows that the optimum IFT range where the IFT is
10.sup.-3 mN/m for OXS 16 is approximately 0.8% to 1.1% NaOH. The
optimum IFT range for OXS 12-28 and OXS 12-28-N are from
approximately 0.5% to 1.6% NaOH. The data indicates that OSX 12-28
and OSX 12-28-N, that are the surfactants derived from broad
distribution alpha-olefins provided tremendous improvement over OSX
16, which is the surfactant made from the narrow distribution of
alpha-olefin.
[0024] FIG. 2 shows the IFT results obtained using various
concentrations of OXS 12-28 without NaOH. The data shows that the
OXS 12-28 alone is not very effective at the low concentrations
ranges of 0.1-0.5%. In order to use this surfactant at
cost-effective concentrations, an alkali is necessary. This is
evident when comparing the IFT values obtained for OXS 12-28 in
FIGS. 1 and 2.
[0025] The above examples served to illustrate the advantages and
unexpected benefits obtained using the method and composition of
the present invention. Specifically the inclusion of alkali(s)
along with alkylaryl sulfonates derived from broad distribution
alpha-olefins provides a composition and a process that uses
ultra-low surfactant concentrations and unexpectedly provides
ultra-low IFT over a wide range of alkali concentrations. The
present invention improves the performance, efficiency and
economics over the traditional alkali surfactant flooding method
using narrow distribution of the alkylaryl sulfonates and the
surfactant flooding method as disclosed in U.S. Pat. No.
6,269,881.
[0026] The invention was described with respect to particularly
preferred embodiments. Modifications within the scope of the
ordinary skilled artisan, e.g., the use of branched alkyl chains
and mixture of aryls and particularly o-xylene alkylate(s) combined
with alkali(s), are within the scope of the invention and the
appended claims.
* * * * *