U.S. patent application number 12/592317 was filed with the patent office on 2011-05-26 for process for oil recovery using multifunctional anionic surfactants.
This patent application is currently assigned to OIL CHEM TECHNOLOGIES. Invention is credited to Christie H. Berger, Paul D. Berger.
Application Number | 20110120707 12/592317 |
Document ID | / |
Family ID | 44061249 |
Filed Date | 2011-05-26 |
United States Patent
Application |
20110120707 |
Kind Code |
A1 |
Berger; Paul D. ; et
al. |
May 26, 2011 |
Process for oil recovery using multifunctional anionic
surfactants
Abstract
A process for the recovery of oil from subterranean reservoirs
by injecting an aqueous fluid containing from about 0.05 to about
2.0% by weight of a surfactant of structure ##STR00001## where
m+n=1-30 or more, x+y=0-28, EO=oxirane, PO=methyl oxirane, M=H, Na,
K, NH.sub.3, Amine, Ca, Mg, R and R1 are each separately and
independently H, branched or linear alkyl, branched or linear
alkenyl, A=aromatic, and, a+b=0 to 30.
Inventors: |
Berger; Paul D.; (Sugar
Land, TX) ; Berger; Christie H.; (Sugar Land,
TX) |
Assignee: |
OIL CHEM TECHNOLOGIES
SUGAR LAND
TX
|
Family ID: |
44061249 |
Appl. No.: |
12/592317 |
Filed: |
November 23, 2009 |
Current U.S.
Class: |
166/270.1 |
Current CPC
Class: |
C09K 8/584 20130101 |
Class at
Publication: |
166/270.1 |
International
Class: |
E21B 43/22 20060101
E21B043/22 |
Claims
1. A process for the recovery of oil from subterranean reservoirs
where a surfactant composition is injected into one or more
injection wells and the oil recovered from one or more producing
wells where said surfactant composition is comprised of a) one or
more surfactants having both a sulfonate and an ether carboxylate
functionality group on the same aromatic molecule with the
structure ##STR00004## Where, A=aromatic, R and R1 are each
separately and independently H, branched or linear alkyl, branched
or linear alkenyl, EO=oxirane, PO=methyl oxirane, m+n=1-30 or more,
x+y=0-28, a+b=0 to 30, and M=H, Na, K, NH.sub.3, Amine, Ca, Mg, b)
an aqueous solvent, e) and, recovering the oil from one or more of
the same or different producing wells.
2. The process for the recovery of oil from subterranean reservoirs
described in claim 1 where the one or more surfactants having both
a sulfonate and an ether carboxylate functionality group on the
same molecule are derived from an aromatic molecule.
3. The process for the recovery of oil from subterranean reservoirs
described in claim 1 where the aromatic is selected from the group
consisting of benzene, toluene, xylene, naphthalene, phenyl
ether.
4. The process for the recovery of oil from subterranean reservoirs
described in claim 1 where the one or more surfactants is present
at a concentration from about 0.05 to about 2% by weight of the
total injected aqueous solvent.
5. The process for the recovery of oil from subterranean reservoirs
described in claim 1 where the co-solvent is selected from the
group consisting of short chain alcohol, glycol, glycerin, glycol
ether.
6. (canceled)
7. The process for the recovery of oil from subterranean reservoirs
described in claim 1 where the aqueous solvent is selected from the
group consisting of water, synthetic brine, injection brine,
produced brine.
8. The process for the recovery of oil from subterranean reservoirs
described in claim 1 where the one or more injection wells may also
serve as the one or more producing wells.
9. The process for the recovery of oil from subterranean reservoirs
described in claim 1 where the one or more injection wells are
different than the one or more producing wells.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] None
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
DESCRIPTION OF ATTACHED APPENDIX
[0003] Not Applicable
BACKGROUND OF THE INVENTION
[0004] The present invention relates to a process for the recovery
of oil from subterranean oil bearing reservoirs, and more
particularly the present invention is to improved oil recovery
involving the injection into reservoirs of a composition containing
anionic surfactants having both ether carboxylate and sulfonate
groups on the same molecule.
[0005] In the recovery of oil from subterranean reservoirs It
usually Is possible to recover approximately 15%-20% of the
original oil in place by primary recovery. Secondary recovery
methods such as well stimulation or water flooding are applied
after the amount of oil recovered by primary recovery becomes
uneconomical. Secondary recovery methods can recover approximately
an additional 15%-30% of the original oil in place which leaves the
reminder of the oil unrecoverable unless other means such as
tertiary recovery processes are applied. These tertiary recovery
methods include but are not limited to the use of miscible and
immiscible gases and liquids, steam, foam, alkali, surfactants, and
polymers.
[0006] It has been known that many factors including but not
limited to the interfacial tension (IFT) between the injection
brine and the residual oil, the relative mobility of the injected
brine, and the wettability characteristics of the rock surfaces
comprising the reservoir are all important in determining the
amount of oil recovered by tertiary recovery. Numerous studies have
found that the addition of surfactants to the injection brine can
after the interfacial and wetting properties to help overcome the
high capillary pressure and increase the oil recovery. In many
cases the addition of a polymer along with the surfactant or
immediately after the surfactant can increase the mobility ratio
between the injected brine and oil thus further improving the sweep
efficiency of the flood.
[0007] Because the injection brine composition varies, it is
important to use the brine available at the injection site for the
oil recovery process in order to be economically feasible. It is
important to have surfactants that are compatible with brines
having wide ranges of total dissolved solids (TDS) and divalent
cations such as those of calcium and magnesium. The problem with
many of the presently used surfactants in tertiary oil recovery is
that they are incompatible with the brines containing high TDS and
divalent cations that are often found at the injection site. Costly
water treatment processes or using an alternate fresh water source
makes the oil recovery process economically unfeasible in many
cases. Therefore it is important to have surfactants that are
tolerant to the high TDS and divalent cations. It is also important
that the surfactant be tolerant to the high temperatures
encountered in some wells and has lower adsorption on to the
reservoir rock. Most surfactants cannot meet all these requirements
and in many cases blends of several different types of surfactants
are used to meet the specific requirements. When blends are used a
strong possibility of chromatographic separation exist as the
surfactant blend propagates through the reservoir due to
differential adsorption properties losing it's effectiveness in IFT
reduction or wettability alteration.
[0008] Anionic sulfonate surfactants are often used in the oil
recovery process to reduce the IFT and higher temperatures because
of their thermal stability. However sulfonates are not tolerant to
brines of high salinities and high divalent cations. Ether
carboxylates are tolerant to high temperatures, high salinities and
high divalent cations but they often fail to give the required low
IFT required to recover oil. The present invention involves the use
of surfactants having to provide the functions suitable for oil
recovery without the disadvantages of using single components or
the mixture of one or more components. Many examples of using
mixtures of two or more surfactants to lower interfacial tension
and recover residual oil can be found in the literature. U.S. Pat.
No. 8,022,834 issued to Hsu et al discloses the use of mixtures of
carboxylated anionic surfactants with sulfonated surfactants. U.S.
Pat. No. 4,458,759 issued to Isaacs teaches a composition
comprising organic sultanate surfactants such as sulfonate fatty
acids having both weak and strong anionic functionality groups.
These products are derived from fatty acids and as such can form
esters but cannot form stable ethers when reacted with ethylene or
propylene oxides and therefore do not exhibit the thermal stability
of the compounds described in the present invention. Processes and
surfactants have been described in the literature using sulfonated
oleic acid, for example, U.S. Pat. No. 3,575,883 to Foley. Besides
being derived from acids to give unstable esters when alkoxylated,
these employ conventional means of sulfonation and are limited to
lower molecular weight products because of reduced sulfonation
efficiency with high molecular weight products. The products of the
present invention use a different sulfonation procedure and are not
limited to low molecular weight products. Therefore highly
alkoxylated products of molecular weights exceeding 1000 can be
easily manufactured. The composition of the present invention is an
ether carboxylate having an additional sulfonate group on the
molecule. The ether carboxylate group has been shown to be very
salt tolerant and thermally stable. The sulfonate group provides
thermal stability as well as lowering the interfacial tension. The
two negative charges on the same molecule help to lower adsorption
unto reservoir rock that is usually negatively charged by
electrostatic repulsion. This combination of an alkyl ether
carboxylate and an alkyl sulfonate attached to an aromatic spacer
disclosed in the present invention is unique and provides
synergistic performance that has not been anticipated before.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0009] An objective of the present invention is to provide a
process for the recovery of oil from subterranean reservoirs using
a surfactant composition to improved oil recovery that is effective
over a wide range of temperatures, electrolyte and divalent anion
concentrations, and is not subject to chromatographic
separation.
[0010] Another objective of the present invention is to provide a
process for the recovery of oil from subterranean reservoirs using
a surfactant composition to improved oil recovery with minimum
adsorption onto the formation.
[0011] Other objectives and advantages of the present invention
will become apparent from the following descriptions, wherein, by
way of illustration and example, an embodiment of the present
invention is disclosed.
[0012] The present invention is directed to the composition
containing surfactants having an ether carboxylate functional group
and a sulfonate functional group on the same molecule, which
composition is formulated into a concentrated surfactant blend
containing an aqueous solvent such as water or brine, and
optionally a co-surfactant/solvent such as a lower molecular weight
alcohol or alcohol ether. The concentrated surfactant blend is
added in a concentration range of about 0.05% to about 5% to the
injection brine and introduced into the subterranean hydrocarbon
containing formation by (a) injecting into said formation through
one or more injection wells, and (b) displacing said solution into
the formation to recover hydrocarbons from one or more production
wells. The injection and producing wells may be the same or
different. Depending on the reservoir conditions, other additives
may be added to the injection brine including strong or weak
alkalis, viscosifiers, corrosion and scale inhibitors, and others
known to those familiar with the art.
[0013] In the present invention, the ether carboxylate group and
the sulfonate groups on the same molecule provide several
advantages over mixtures of surfactants having each of the
functionalities on separate molecules. The single molecule
containing the two groups eliminates the possibility of chromatic
separation when subjected to a strong adsorbent such as when
injected into an oilfield reservoir.
[0014] Structure I below describes the compound of this invention.
This structure shows the aromatic group to be a single ring
structure. Multiple ring structures including but not limited to
naphthalenes or phenyl ethers are also part of the present
invention.
##STR00002##
Where,
[0015] A=aromatic R and R1 are each separately and independently H,
branched or linear alkyl, branched or linear alkenyl, m+n=1-30 or
more, x+y=0-28, EO=oxirane, PO=methyl oxirane,
M=H, Na, K, NH.sub.3, Amine, Ca, Mg,
[0016] a+b=0 to 30.
[0017] The product described in Structure I is made by reacting an
unsaturated ether carboxylate with sulfonio acid Structure II. The
procedure for obtaining Structure I is described in U.S. Pat. No.
6,043,391. The addition of ethylene oxide and/or propylene oxide to
an alcohol, followed by carboxylation to form alcohol ether
carboxylates gives these carboxylates salt and divalent cation
tolerance and thermal stability.
##STR00003##
Where
[0018] A=aromatic, including but is not restricted to benzene,
toluene, xylene, naphthalene, diphenyl ether, R, R.sub.1 are each
separate and independently H, branched or linear alkyl, branched or
linear alkenyl,
R.sub.2.dbd.H,
[0019] a+b=0 to 30.
[0020] The unsaturated carboxylate moiety may contain from about 0
to about 30 or more moles of an alkoxy group such as ethylene oxide
(EO), propylene oxide (PO), or mixtures of EO and PO, or sequences
of EO and PO, to adjust the solubility and molecular weight of the
surfactant. Unsaturated ether carboxylates include but are not
limited to oleyl alcohol ether carboxylates, erucyl alcohol ether
carboxylates, nervonyl alcohol ether carboxylates.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Detailed descriptions of the preferred embodiment are
provided herein. It is to be understood, however, that the present
invention may be embodied in various forms. Therefore, specific
details disclosed herein are not to be interpreted as limiting, but
rather as a basis for the claims and as a representative basis for
teaching one skilled in the art to employ the present invention in
virtually any appropriately detailed system, structure or
manner.
[0022] The present invention is directed to a high salinity, high
divalent cation and high temperature tolerant, low adsorption
surfactant.
[0023] The present invention also includes a process using
compositions containing surfactants described in Structure I to
recover oil from subterranean reservoirs. For this process
Structure I is usually formulated into a concentrated surfactant
blend at levels of 5 to 80 wt % or more in an aqueous solvent such
as water or brine, and optionally a co-surfactant/solvent such as a
lower molecular weight alcohol, or alcohol ether, and optionally a
pH control agent. Non-exclusive examples of the
co-surfactant/solvent are iso-propanol, n-butanol, and ethylene
glycol monobutyl ether. The concentrated surfactant solution is
added in a concentration range of about 0.05% to about 5% to an
injection fluid or brine and introduced into the subterranean
hydrocarbon containing formation by (a) injecting into said
formation through one or more injection wells, and (b) displacing
said solution into the formation to recover hydrocarbons from one
or more production wells. The injection and producing wells may be
the same or different. Depending on the reservoir conditions, other
additives may be added to the injection brine including strong or
weak alkalis, viscosifiers, corrosion and scale inhibitors, and
others known to those familiar with the art. Gases including but
not limited to N.sub.2 or CO.sub.2 can also be used to inject the
surfactant into the reservoir.
[0024] The concentrated surfactant blends containing structure I
have been found to be compatible with a wide range of brines
containing different amount of total dissolved solids and
multivalent cations such as Ca.sup.+2 and Mg.sup.+2 and very stable
to high temperatures exceeding 150.degree. C.
[0025] In accordance with a preferred embodiment of the invention,
there is disclosed a process for improving the recovery of oil by
injecting into one or more injection wells a fluid containing
[0026] a) one or more surfactants described in structure I,
[0027] b) an aqueous solvent,
[0028] c) optionally one or more co-surfactants/solvents,
[0029] d) optionally a viscosity increasing agent, and
[0030] e) optionally an alkali,
[0031] and, recovering the oil from one or more of the same or
different producing wells.
[0032] The aqueous solvent may be water or a synthetic brine or a
brine that is produced from the reservoir. The
co-surfactant/solvent includes, but is not limited to, a short
chained alcohol, glycol, or ether such as methanol, ethanol,
propanol, isopropanol, butanol, iso-butanol, glycerin, ethylene
glycol, propylene glycol, ethylene glycol monobutyl ether. The
alkali includes but is not limited to sodium hydroxide or sodium
carbonate, organic alkali. Organic alkalis include, but are not
limited to, salts of weka acids and salts of polymerized weak
acids. The viscosity improving agent includes, but is not limited
to, any of a number of polymers known to those familiar with the
art including polyacrylamide, xanthan gum, and block polymers of
acrylamide and copolymer of acrylic acid and
2-Acrylamido-2-Methylpropyl Sulfonic Acid (AMPS).
[0033] Following are examples illustrating the utility of the
present invention for application in the recovery of oil from
subterranean reservoirs. The interfacial tension (IFT) between the
crude oil/injection brine using the composition of the present
invention is used to illustrate the efficiency of the present
invention. It is well documented that after primary oil recovery
and secondary oil recovery the Capillary Number is about 10.sup.-8
[See for Instance Basic Concepts In Enhanced Oil Recover Processes,
p 18-19, 90]. The capillary number is defined as:
Nc=.mu.V/.sigma.
[0034] where
Nc=Capillary Number
[0035] .mu.=displacing fluid viscosity V=interstitial velocity
.sigma.=IFT between the displacing fluid and the crude oil.
[0036] Increasing the Capillary Number to a value above 10.sup.-3
has been shown to result in a substantial increase in the recovery
of trapped oil after waterflooding has become ineffective (Basic
Concepts in Enhanced Oil Recover Processes, p 108). The viscosity
and the velocity cannot be increased substantially without damaging
the reservoir; however, the IFT can easily be reduced 3 to 4 orders
of magnitude by the proper choice of surfactant. Thus a surfactant
can reduce the IFT between an oil and an aqueous medium from 3-30
mN/m to less than 10.sup.-2 mN/m resulting in an increase in the
capillary number to greater than 10.sup.-2 and improve the oil
recovery.
[0037] In the following examples, IFT has been used as a measure of
the suitability of a particular surfactant as a candidate for
enhanced oil recovery.
[0038] Table I lists the surfactants used to in the examples chosen
to demonstrate the utility and novelty of the invention. In all
cases the surfactant formulation consisted of 30% by weight
surfactant, 25% by weight ethylene glycol monobutyl ether
(co-surfactant/solvent), and 45% by weight water. Also in all cases
the surfactant formulation was added to the injection brine at a
concentration of 0.10 weight percent. These examples use
surfactants containing only ethylene oxide in the alcohol ether
carboxylate although products containing propylene oxide and
ethylene oxide give good results in certain applications.
TABLE-US-00001 TABLE I Surfactants Used In Examples SURFACTANT
CHEMICAL DESCRIPTION A Structure I where x = 7, y = 8, m = 0, n =
2, M = Na, and a + b = 11. B Structure I where x = 7, y = 8, m = 0,
n = 9, M = Na, and a + b = 11. C Sodium salt of carboxylated oleyl
alcohol with 2 moles of EO. D Sodium salt of carboxylated oleyl
alcohol with 9 moles of EO. E Sodium salt of structure II where a +
b = 11
[0039] Table II is the brine compositions that were used for the
IFT testing to show the effect of total dissolved solids and
divalent ion concentration on the IFT obtained using various
surfactants.
TABLE-US-00002 TABLE II Brine Compositions BRINE 1 2 3 4 5 NaCl, %
3.0 1.0 5.0 10 20 CaCl2--2H2O, % 1.0 0 0 0 0 MgCl2--6H2O, % 1.0 0 0
0 0
[0040] Table III compares the solubilities obtained with 5.0% by
weight of various surfactant concentrates in the 5 brines at
30.degree. C.
TABLE-US-00003 TABLE III Brine Solubilities SURFAC- BRINE BRINE
TEST TANT BRINE 1 2 3 BRINE 4 BRINE 5 1 A soluble soluble soluble
insoluble insoluble 2 B soluble soluble soluble soluble dispersible
3 C dispersible soluble soluble soluble dispersible 4 D soluble
soluble soluble soluble soluble 5 E insoluble soluble in- insoluble
insoluble soluble 6 C + E insoluble soluble in- insoluble insoluble
soluble 7 D + E insoluble soluble in- insoluble insoluble
soluble
[0041] Table III shows the unexpected result that the various
surfactants where the sulfonate and ether carboxylate are on the
same molecule are soluble in all the brines tested whereas in many
cases the individual sultanates (E) and mixtures of the sulfonates
and alcohol ether Carboxylates (C+E and D+E) are not.
[0042] Tables IV and V shows the interfacial tension (IFT) in
millineutons/meter (mN/m) against a crude oil having 27 API Gravity
at 95.degree. C. for 0.1 wt % surfactant. All IFTs were obtained
using a University of Texas Model 500 spinning drop interfacial
tensiometer after spinning at 95.degree. C. for 1 hour. The data
shows low IFT can be obtained with low surfactant concentration
when the amount of ethylene oxide averages 3.8 to 8.8 Moles/Mole of
oleyl alcohol.
TABLE-US-00004 TABLE IV IFT Properties SURFAC- BRINE BRINE TEST
TANT BRINE 1 2 3 BRINE 4 BRINE 5 1 A 0.891 0.005 0.012 insoluble
insoluble 2 B 0.356 0.009 0.003 0.003 0.002 3 C 0.769 0.070 0.090
0.122 0.256 4 D 0.066 0.031 0.022 0.020 0.020 5 E insoluble 0.007
in- insoluble insoluble soluble 6 C + E insoluble 0.005 in-
insoluble insoluble soluble 7 D + E insoluble 0.009 in- insoluble
insoluble soluble
Table V also shows that the individual surfactants A and B
containing 2 and 9 moles of ethylene oxide respectively do not give
ultra-low IFTs with brine 1; however blends containing various
amounts of the two do give IFTs below 10.sup.-2 mN/m.
TABLE-US-00005 TABLE V Comparison of IFTs with Various Surfactant
Mixtures Avg Mole A wt % B wt % EO BRINE 1 100 0 2.0 0.891 75 25
3.8 0.0080 50 50 5.5 0.0058 25 75 6.8 0.0023 0 100 9.0 0.356
[0043] Table VI shows the IFTs obtained using individual
surfactants defined by structure I where the moles of EO are have
been varied from 2 to 9. This shows that the single surfactant
system can give the same IFT values as the blends from Table IV
with the additional advantage of having no possibility of
chromatographic separation since they are single component
systems.
TABLE-US-00006 TABLE VI IFT for Various Single Component Systems
Mole EO BRINE 1 2.0 0.891 4.0 0.0080 6.0 0.0051 7.0 0.0035 8.0
0.093 9.0 0.356
Table VII compares the adsorption of the composition of this
invention surfactant B with a 1:1 molar mixture of surfactant D and
surfactant E to show the effectiveness of having both the sulfonate
and ether carboxylate on one molecule. 0.2 wt % surfactant D and
0.2 wt % surfactant E alone were also included to correct for the
amount of each of these surfactants adsorbed. All tests were done
using 0.20 wt % total surfactant in Brine 2. The static adsorption
was run by mixing 50.0 grams of surfactant solution with 10.0 grams
of 200 mesh beach sand on a wrist action shaker for 16 hours and
than determining the amount of surfactant remaining compared to the
original amount added. Table VII shows the amount adsorbed in mg
surfactant/gram sand.
TABLE-US-00007 TABLE VII Adsorption Tests Original Amount wt, g
remaining Adsorbed mg/g % adsorbed Surfactant B 0.100 0.096 0.014
1.4 14 Surfactant D + E 0.100 0.039 0.061 6.1 61 Surfactant D 0.100
0.022 0.078 7.8 78 Surfactant E 0.100 0.045 0.055 5.6 55
The data from Table VII shows that the alcohol ether carboxylate
(surfactant D) is strongly adsorbed (78%) onto the send. The
sulfonate (surfactant E) is not adsorbed as much however this
product is not compatible with brines having salt concentrations of
5 wt % or more as shown in Table III. The mixing of surfactant E
and surfactant D indicates that the adsorption of surfactant D is
very large and not reduced by mixing with surfactant E, However,
the adsorption of the composition of this invention surfactant B is
very low. This indicates that an unexpected synergistic effect
occurs when the alcohol ether carboxylate and the sulfonate are
combined on the same molecule.
[0044] While the invention has been described in connection with a
preferred embodiment, it is not intended to limit the scope of the
invention to the particular form set forth, but on the contrary, it
is intended to cover such alternatives, modifications, and
equivalents as may be included within the spirit and scope of the
invention as defined by the appended claims.
* * * * *