U.S. patent application number 13/957012 was filed with the patent office on 2014-02-06 for enhanced oil recovery methods using a fluid containing a sacrificial agent.
The applicant listed for this patent is Shell Oil Company. Invention is credited to Marten Marten BUIJSE, Jeffrey George SOUTHWICK, Diederik Willem VAN BATENBURG, Carolus Hendricus Theodorus VAN RIJN.
Application Number | 20140034306 13/957012 |
Document ID | / |
Family ID | 50024337 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140034306 |
Kind Code |
A1 |
SOUTHWICK; Jeffrey George ;
et al. |
February 6, 2014 |
ENHANCED OIL RECOVERY METHODS USING A FLUID CONTAINING A
SACRIFICIAL AGENT
Abstract
A method and a system for producing petroleum from a formation
utilizing a sacrificial agent and a surfactant are provided. The
sacrificial agent reduces the amount of surfactant required to
enhance oil recovery from a petroleum-bearing formation. The
sacrificial agent is provided in a oil recovery formulation
comprising a sacrificial agent and a surfactant dispersed in a
fluid. The sacrificial agent is selected from the group consisting
of a compound comprising a single carboxylic acid, a single
carboxylic acid derivative, or a single carboxylate salt, or a
compound lacking a carboxylic acid group, a carboxylate group, a
sulfonic acid group, or a sulfonate group that is a pheol, a
sulphonamide, or a thiol, or a compound having a molecular weight
of 1000 or less that comprises one or more hydroxyl groups. The oil
recovery formulation is introduced into a petroleum-bearing
formation and petroleum is produced therefrom.
Inventors: |
SOUTHWICK; Jeffrey George;
(Houston, TX) ; BUIJSE; Marten Marten; (Rijswijk,
NL) ; VAN BATENBURG; Diederik Willem; (Rijswijk,
NL) ; VAN RIJN; Carolus Hendricus Theodorus;
(Rijswijk, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shell Oil Company |
Houston |
TX |
US |
|
|
Family ID: |
50024337 |
Appl. No.: |
13/957012 |
Filed: |
August 1, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61679180 |
Aug 3, 2012 |
|
|
|
Current U.S.
Class: |
166/270.1 ;
166/52 |
Current CPC
Class: |
C09K 8/584 20130101;
C09K 8/58 20130101; E21B 43/25 20130101 |
Class at
Publication: |
166/270.1 ;
166/52 |
International
Class: |
E21B 43/25 20060101
E21B043/25 |
Claims
1. A method comprising: providing an oil recovery formulation
comprising a fluid, a surfactant dispersed in the fluid, and a
sacrificial agent dispersed in the fluid, wherein the sacrificial
agent is selected from the group consisting of a compound
comprising a single carboxylic acid, a single carboxylic acid
derivative, or a single carboxylate salt; a compound lacking a
carboxylic acid group, a carboxylate group, a sulfonic acid group,
and a sulfonate group that is a phenol, a sulfonamide, or a thiol;
a compound having a molecular weight of 1000 or less and comprising
one or more hydroxyl groups; and mixtures thereof; introducing the
oil recovery formulation into a petroleum-bearing formation;
contacting the oil recovery formulation with the petroleum-bearing
formation and with petroleum in the petroleum-bearing formation;
and producing petroleum from the petroleum-bearing formation after
introducing the oil recovery formulation into the petroleum-bearing
formation.
2. The method of claim 1, wherein the petroleum-bearing formation
is a subterranean formation.
3. The method of claim 2, wherein the oil recovery formulation is
introduced into the formation via a first well and the petroleum is
produced via a second well.
4. The method of claim 3, further comprising producing at least a
portion of the oil recovery formulation from the second well.
5. The method of claim 4, further comprising introducing at least a
portion of the produced oil recovery formulation to the
subterranean formation.
6. The method of claim 1, wherein the oil recovery formulation
further comprises an alkali and a polymer.
7. The method of claim 6, wherein the polymer is selected from the
group consisting of polyacrylamides, partially hydrolyzed
polyacrylamides, polyacrylates, ethylenic co-polymers, biopolymers,
carboxymethylcelloluses, polyvinyl alcohols, polystyrene
sulfonates, polyvinylpyrrolidones, AMPS (2-acrylamide-methyl
propane sulfonate), and combinations thereof and the alkali is
selected from the group consisting of lithium hydroxide, sodium
hydroxide, potassium hydroxide, lithium carbonate, sodium
carbonate, potassium carbonate, lithium bicarbonate, sodium
bicarbonate, potassium bicarbonate, lithium silicate, lithium
phosphate, sodium silicate, sodium phosphate, potassium silicate,
and potassium phosphate, and mixtures thereof.
8. The method of claim 1, wherein the sacrificial agent comprises a
monohydroxycarboxylic acid, a dihydroxycarboxylic acid, a
trihydroxycarboxylic acid, a tetrahydroxycarboxylic acid, a
pentahydroxycarboxylic acid, a salt thereof, or any combination
thereof.
9. The method of claim 1, wherein the sacrificial agent comprises
10 carbons or less.
10. The method of claim 1, wherein the sacrificial agent comprises
an oxidizable functional group.
11. The method of claim 10, further comprising oxidizing the
sacrificial agent while contacting the petroleum-bearing
formation.
12. The method of claim 1, wherein the sacrificial agent comprises
an enol.
13. The method of claim 1, wherein the sacrificial agent comprises
a reductone.
14. The method of claim 13, wherein the sacrificial agent further
comprises a carboxylic acid derivative selected from the group
consisting of an ester and an amide.
15. The method of claim 14, wherein the sacrificial agent comprises
a lactone or a lactam.
16. The method of claim 1, wherein the sacrificial agent comprises
a carbohydrate selected from the group consisting of a
monosaccharide, a disaccharide, a trisaccharide, a tetrasaccharide,
a pentasaccharide, or any combination thereof, wherein the
carbohydrate comprises at least one reducing sugar.
17. The method of claim 1, wherein the sacrificial agent is
selected from the group consisting of erythorbic acid, ascorbic
acid, dehydroerythorbic acid, dehydroascorbic acid, a derivative
thereof, or a salt thereof, and any combination thereof.
18. The method of claim 1, wherein the sacrificial agent comprises
from 0.001 wt. % to 5 wt. %, or from 0.01 wt. % to 0.5 wt. % of the
oil recovery formulation.
19. The method of claim 1, wherein the surfactant is an anionic
surfactant.
20. The method of claim 19, wherein the surfactant is selected from
the group consisting of an alpha olefin sulfonate compound, an
internal olefin sulfonate compound, a branched alkyl benzene
sulfonate compound, a propylene oxide sulfate compound, or a blend
thereof.
21. The method of claim 1, wherein the surfactant comprises from
0.05 wt. % to 5 wt. %, or from 0.2 wt. % to 1 wt. % of the oil
recovery formulation.
22. The method of claim 1, wherein the fluid of the oil recovery
formulation is water or an aqueous brine.
23. A system, comprising: an oil recovery formulation comprising a
fluid, a surfactant dispersed in the fluid, and a sacrificial agent
dispersed in the fluid, wherein the sacrificial agent is selected
from the group consisting of a compound comprising a single
carboxylic acid, a single carboxylic acid derivative, or a single
carboxylate salt; a compound lacking a carboxylic acid group, a
carboxylate group, a sulfonic acid group, and a sulfonate group
that is a phenol, a sulfonamide, or a thiol; a compound having a
molecular weight of 1000 or less and comprising one or more
hydroxyl groups; and mixtures thereof; a petroleum-bearing
formation; a mechanism for introducing the oil recovery formulation
into the petroleum-bearing formation; and a mechanism for producing
petroleum from the petroleum-bearing formation subsequent to
introduction of the oil recovery formulation into the
formation.
24. The system of claim 23, wherein the petroleum-bearing formation
is a subterranean formation.
25. The system of claim 24, wherein the mechanism for introducing
the oil recovery formulation into the formation is located at a
first well, wherein the first well extends into the subterranean
formation.
26. The method of claim 25, wherein the mechanism for producing the
petroleum from the formation is located at a second well, wherein
the second well extends into the subterranean formation.
27. The method of claim 23, wherein the surfactant is an anionic
surfactant.
28. The method of claim 23, wherein the oil recovery formulation
further comprises a polymer.
29. The system of claim 28, wherein the oil recovery formulation
further comprises an alkali.
30. The system of claim 23, wherein the sacrificial agent is
selected from the group consisting of erythorbic acid, ascorbic
acid, a salt thereof, and any combination thereof.
Description
[0001] This present application claims the benefit of U.S. Patent
Application No. 61/679,180, filed Aug. 3, 2012.
FIELD OF THE INVENTION
[0002] The present invention is directed to methods for recovering
petroleum from a formation, and, in particular, the present
invention is directed to methods of enhanced oil recovery using a
surfactant.
BACKGROUND OF THE INVENTION
[0003] Production of petroleum from a formation can be
characterized by at least three different stages of production.
During primary production, innate driving forces within the
formation are sufficient to drive the petroleum from the formation,
such as from the depths of a subterranean formation to the earth's
surface. Innate driving forces may include natural
pressure-generation mechanisms within the formation such as, for
example, downward water displacement, natural gas expansion, and
gravity-induced drainage within a well. At some point, the innate
driving forces may decrease to such a degree that production
significantly wanes or stops. In secondary production, an
externally applied force may be supplied to the formation to
provide sufficient energy to remove the petroleum therefrom. The
externally applied force may include, for example, an injected
fluid that creates fluid pressure that supplements or replaces that
of the innate driving forces within the formation. External lifting
mechanisms such as pumps may also be used to assist in production
of the petroleum.
[0004] After secondary production no longer produces sufficient
petroleum to be economically viable, there may, in many instances,
still be substantial residual petroleum within the formation.
Insufficient mobility of the petroleum within the formation may be
one of the causes leading to its retention. Mobility of petroleum
within a formation may be related to the innate viscosity of the
petroleum, interfacial tension between the petroleum and the
formation, combinations thereof, and the like. In tertiary
production, also referred to as enhanced oil recovery techniques,
the mobility of petroleum within the formation is altered in some
manner, thereby inducing mobilization and production of the
petroleum to take place. Techniques for altering the mobility of
the petroleum within the formation may include heating the
petroleum to reduce its viscosity, introducing a miscible fluid
such as carbon dioxide or a hydrocarbon to the petroleum to reduce
its viscosity, or introducing a fluid containing a surfactant to
the formation to reduce the interfacial tension between the
petroleum and the formation. Although it was once conventional to
conduct enhanced oil recovery techniques following the completion
of primary and secondary production, it is now common to employ
these techniques at any point during a production operation. That
is, enhanced oil recovery techniques may be employed during primary
or secondary production or as a separate production operation.
[0005] One problem that may be frequently encountered when lowering
the interfacial tension within a formation using a surfactant is
that of excessive surfactant sorption to the surface of the
formation. As used herein, the term "sorption" collectively refers
to absorption, adsorption, or any combination thereof. Excessive
surfactant sorption to the formation may limit the surfactant's
ability to reduce interfacial tension within a desired region of
the formation. Although additional surfactant can be introduced to
the formation to offset that rendered ineffective by sorption, such
an approach may be undesirable from an economic standpoint, since
many surfactants can be relatively costly. For at least this
reason, it is ordinarily desirable to limit the amount of
surfactant used during enhanced oil recovery production.
[0006] To address surfactant sorption within a formation,
sacrificial agents are often used in conjunction with a surfactant.
As used herein, the term "sacrificial agent" refers to a substance
that mitigates the sorption of a surfactant to a formation or
otherwise reduces the retention of the surfactant within the
formation. Without limitation or being bound by theory or
mechanism, the sacrificial agent may modify the surface of the
formation or itself be sorbed to the formation such that sorption
of the surfactant is reduced or eliminated. Ideally, the
sacrificial agent is less costly than the surfactant, thereby
allowing better process economics to be realized. Commonly used
sacrificial agents may include, for example, inorganic salts,
water-soluble polymer viscosifiers, lignosulfonates, cellulose and
cellulose derivatives, starch and starch derivatives, and polybasic
carboxylic acids, particularly chelating acids. Chelating acids may
be particularly advantageous in this regard, since they may chelate
metal ions, such as calcium and magnesium, that may react with
surfactants and render them ineffective for reducing the
interfacial tension within a formation.
SUMMARY OF THE INVENTION
[0007] In one aspect, the present invention is directed to a method
for recovering petroleum comprising:
[0008] providing an oil recovery formulation comprising a fluid, a
surfactant dispersed in the fluid, and a sacrificial agent
dispersed in the fluid, wherein the sacrificial agent is selected
from the group consisting of a compound comprising a single
carboxylic acid, a single carboxylic acid derivative, or a single
carboxylate salt; a compound lacking a carboxylic acid group, a
carboxylate group, a sulfonic acid group, and a sulfonate group
that is a phenol, a sulfonamide, or a thiol; a compound having a
molecular weight of 1000 or less and comprising one or more
hydroxyl groups; and mixtures thereof;
[0009] introducing the oil recovery formulation into a
petroleum-bearing formation;
[0010] contacting the oil recovery formulation with the
petroleum-bearing formation and with petroleum in the
petroleum-bearing formation; and
[0011] producing petroleum from the petroleum-bearing formation
after introducing the oil recovery formulation into the
petroleum-bearing formation.
[0012] In another aspect, the present invention is directed to an
oil recovery composition comprising, [0013] a fluid; [0014] a
sacrificial agent selected from the group consisting of a compound
comprising a single carboxylic acid, a single carboxylic acid
derivative, or a single carboxylate salt; a compound lacking a
carboxylic acid group, a carboxylate group, a sulfonic acid group,
and a sulfonate group that is a phenol, a sulfonamide, or a thiol;
a compound having a molecular weight of 1000 or less and comprising
one or more hydroxyl groups; and mixtures thereof, wherein the
sacrificial agent is dispersed in the fluid; and [0015] a
surfactant.
[0016] In another aspect, the present invention is directed to a
system, comprising an oil recovery formulation comprising a fluid,
a surfactant dispersed in the fluid, and a sacrificial agent
dispersed in the fluid, wherein the sacrificial agent is selected
from the group consisting of a compound comprising a single
carboxylic acid, a single carboxylic acid derivative, or a single
carboxylate salt; a compound lacking a carboxylic acid group, a
carboxylate group, a sulfonic acid group, and a sulfonate group
that is a phenol, a sulfonamide, or a thiol; a compound having a
molecular weight of 1000 or less and comprising one or more
hydroxyl groups; and mixtures thereof; [0017] a petroleum-bearing
formation; [0018] a mechanism for introducing the oil recovery
formulation into the petroleum-bearing formation; and [0019] a
mechanism for producing petroleum from the petroleum-bearing
formation subsequent to introduction of the oil recovery
formulation into the formation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is an illustration of a petroleum production system
in accordance with the present invention.
[0021] FIG. 2 is a diagram of a well pattern for production of
petroleum in accordance with a system and process of the present
invention.
[0022] FIG. 3 is a diagram of a well pattern for production of
petroleum in accordance with a system and process of the present
invention.
[0023] FIGS. 4 and 5 respectively show illustrative retention plots
of various fluid components in the presence and absence of
erythorbic acid.
[0024] FIG. 6 shows an illustrative production chart for an oil
recovery flood in which erythorbic acid was added to an ASP
slug.
DETAILED DESCRIPTION OF THE INVENTION
[0025] The present invention is directed to methods for recovering
petroleum from a formation, and, in particular, the present
invention is directed to methods of enhanced oil recovery using a
surfactant. More specifically, the present invention is directed to
methods of enhanced oil recovery using an oil recovery formulation
comprising a surfactant and a sacrificial agent, where the
sacrificial agent may comprise a single carboxylic acid, carboxylic
acid derivative, or carboxylate salt; or an acidic substance or
salt of an acidic substance that lacks a carboxylic acid, sulfonic
acid, or a salt thereof; or a compound having a molecular weight of
about 1000 or less and having one or more hydroxyl groups.
[0026] As discussed above, a number of different types of
sacrificial agents have been used in conjunction with the
introduction of surfactants to a petroleum-bearing formation,
particularly during enhanced oil recovery operations. Although
these sacrificial agents have been used with varying degrees of
success, the discovery and development of new sacrificial agents
may be desirable to increase operational flexibility for a given
application, to reduce costs associated with the surfactant and/or
the sacrificial agent, and/or to increase the amount of petroleum
produced from the formation.
[0027] When a petroleum-bearing formation is in its native
environment (e.g., in a subterranean formation), the formation may
be in a reduced state. When removed from its native environment,
such as in a core sample obtained from the formation for oil
recovery studies, oxidation may occur, thereby changing the
oxidative state of the core sample and its properties. To return
the core sample to a reduced state that may be more like that
natively present within a subterranean formation, the core sample
may be treated with a reducing agent before conducting testing
further thereon. Sodium dithionite is often used for this
purpose.
[0028] In enhanced oil recovery operations, an oil recovery
formulation containing a polymer and a surfactant may be utilized
to enhance oil recovery from a formation. An alkali may often be
present as well. These two types of enhanced oil recovery
operations are commonly referred to as surfactant-polymer (SP) and
alkali-surfactant-polymer (ASP) floods, respectively. In the
process of testing an ASP flood on a sodium dithionite-reduced core
sample, polymer degradation was observed, which was believed to be
promoted by the sodium dithionite. Accordingly, the core sample
reduction was conducted using erythorbic acid, which is a milder
reducing agent, followed by an ASP core flood. Surprisingly,
treatment of the core sample with erythorbic acid significantly
decreased retention of the surfactant within the core sample.
Although providing the desired core reduction, sodium dithionite,
in contrast, did not significantly impact retention of the
surfactant within the core sample.
[0029] The present invention is directed to a process, a system,
and a composition for enhanced oil recovery from a
petroleum-bearing formation. The oil recovery formulation
composition of the present invention comprises a surfactant and a
sacrificial agent having one or more chemical structural attributes
of erythorbic acid. The oil recovery formulation may also include a
polymer and/or a basic compound. The sacrificial agent is effective
to decrease retention of the surfactant in the petroleum-bearing
formation. The process of the present invention utilizes the oil
recovery formulation composition and the system of the present
invention to produce petroleum from a petroleum-bearing formation.
The oil recovery formulation is introduced into a petroleum-bearing
formation and is contacted with petroleum in the petroleum-bearing
formation. Petroleum is produced from the petroleum-bearing
formation subsequent to contacting the oil recovery formulation
with petroleum in the petroleum-bearing formation. In a preferred
embodiment, the oil recovery formulation comprises a surfactant and
erythorbic acid.
[0030] The oil recovery formulation composition comprises a
sacrificial agent having one or more chemical structural attributes
of erythorbic acid. The structure of erythorbic acid is shown below
in Formula 1. Erythorbic acid is an enantiomer of ascorbic acid,
also known as Vitamin C, which shown in Formula 2, and ascorbic
acid may function as a sacrificial agent in a like manner to
erythorbic acid.
##STR00001##
[0031] As putative sacrificial agents, erythorbic acid and ascorbic
acid contain several chemical structural features, any of which,
separately or together, may contribute to a surprising decrease of
surfactant retention within a formation to which the oil recovery
formulation has been introduced. Erythorbic acid and ascorbic acid
contain both neutral alcohol-type hydroxyl groups and enol-type
hydroxyl groups, the latter of which confer acidity to the
compounds. Erythorbic acid and ascorbic acid also contain
considerably fewer hydroxyl groups than carbohydrate- and
starch-based sacrificial agents that have been previously used in
the art. The enol-type hydroxyl groups of erythorbic and ascorbic
acids' reductone structures may also be readily oxidized to a
diketone, thereby allowing erythorbic acid and ascorbic acid to
function as mild reducing agents. The oxidation products of
erythorbic acid and ascorbic acid, dehydroerythorbic acid and
dehydroascorbic acid, respectively, may also play a role in
decreasing surfactant retention within a petroleum-bearing
formation. These compounds are shown in Formulas 3 and 4,
respectively. In addition, erythorbic acid and ascorbic acid may
undergo lactone hydrolysis under formation temperature and pressure
conditions within a petroleum-bearing formation to liberate a free
carboxylic acid, which may also contribute to reducing the
surfactant retention.
##STR00002##
[0032] In addition to the above features, erythorbic acid and
ascorbic acid may form weakly bound chelates with metal ions.
Without being bound by theory or mechanism, it is believed that
chelation of the sacrificial agent to a formation surface to
permanently block a potential surfactant binding site may play only
a minor role in their function as sacrificial agents, given their
fairly weak chelation properties, although weak chelation of the
sacrificial agent with the formation surface may inhibit binding of
a surfactant to the formation surface for the period of time until
the sacrificial agent releases from the formation surface. It is
believed that erythorbic acid and ascorbic acid may be
distinguished from polybasic carboxylic acid chelation agents since
they lack a free carboxylic acid group for metal ion chelation.
Even in their hydrolyzed form, they still lack a second carboxylic
acid group needed for strong metal ion chelation to take place.
[0033] In one aspect, the oil recovery formulation may comprise a
sacrificial agent compound comprising a single carboxylic acid,
carboxylic acid derivative, or carboxylate salt moiety. As used
herein, the term "carboxylic acid derivative" refers to a compound
containing a reaction product of a carboxylic acid moiety that does
not retain a free carboxylic acid hydroxyl group. Illustrative
carboxylic acid derivatives include esters and amides, which may
comprise a lactone or a lactam. The sacrificial agent compound
containing a single carboxylic acid moiety, carboxylic acid
derivative moiety, or carboxylate salt moiety may also contain one
or more hydroxyl groups.
[0034] The sacrificial agent of the oil recovery formulation may
comprise a monocarboxylic acid compound or a salt thereof. As used
herein, the term "monocarboxylic acid compound" refers to a
compound containing only one carboxylic acid group or carboxylate
group. The monocarboxylic acid compound of the sacrificial agent
may be a hydrocarbon comprising 10 carbons or fewer, or 9 carbons
or fewer, or 8 carbons or fewer, or 7 carbons or fewer, or 6
carbons or fewer, or 5 carbons or fewer. The monocarboxylic acid
compound may contain from 2-10 carbons, or from 3-9 carbons, or
from 4-8 carbons. The monocarboxylic acid compound may comprise a
straight carbon chain or may comprise a branched carbon chain. The
monocarboxycylic acid compound may comprise a non-aromatic cyclic
carbon ring, optionally with branching, or may comprise an aromatic
ring, optionally with branching. The carbon chain or ring may
contain one or more heteroatoms selected from the group consisting
of oxygen, nitrogen, and sulfur within the chain or ring.
[0035] The monocarboxylic acid compound of the sacrificial agent
may be a hydroxycarboxylic acid compound comprising one or more
hydroxyl groups. The hydroxycarboxylic acid compound may comprise a
straight carbon chain or a branched carbon chain. The
hydroxycarboxylic acid compound may comprise a non-aromatic cyclic
carbon ring or an aromatic cyclic carbon ring, optionally with
branching. The carbon chain or ring may comprise one or more
heteroatoms selected from the group consisting of oxygen, sulfur,
and nitrogen within the chain or ring. Hydroxycarboxylic acid
compounds suitable for use as a sacrificial agent compound of the
oil recovery formulation may include from 1 to 10 hydroxyl groups,
or from 1 to 6 hydroxyl groups, or from 1 to 3 hydroxyl groups. The
sacrificial agent may comprise a compound that is a
monohydroxycarboxylic acid, a dihydroxycarboxylic acid, a
trihydroxycarboxylic acid, a tetrahydroxycarboxylic acid, a
pentahydroxycarboxylic acid, a salt thereof, or any combination
thereof. The sacrificial agent may comprise a compound that is an
.alpha.-hydroxycarboxylic acid, a .beta.-hydroxycarboxylic acid, a
.gamma.-hydroxycarboxylic acid, a .delta.-hydroxycarboxylic acid,
an .epsilon.-hydroxycarboxylic acid, a salt thereof, or any
combination thereof.
[0036] The sacrificial agent of the oil recovery formulation may
comprise a compound comprising an enol or that is enolizable,
including stabilized enols. In some embodiments, the enol may only
form as a transient tautomer where the enol may not persist as an
abundant and observable species. As used herein, the term
"stabilized enol" refers to a compound containing a hydroxyl group
bound to a doubly-bonded carbon in which at least some of the enol
tautomer persists as an abundant and observable species. Compounds
such as .beta.-diketones, .beta.-ketoesters, and some acyloins may
produce a stabilized enol. Reductones are another class of
compounds that may produce a stabilized enol. As used herein, the
term "reductone" refers to a compound having an enediol
functionality located adjacent to a carbonyl group. Suitable
reductone compounds may be straight chain, branched, or cyclic.
Reductone compounds that may be used as the sacrificial agent or a
portion thereof may have a structure as defined by Formula 5 below,
wherein R.sub.1 and R.sub.2 comprise a carbon-containing group
having between 1 and 10 carbon atoms and R.sub.1 and R.sub.2 are
the same or different. Reductone compounds that may be used as the
sacrificial agent or a portion thereof may have a structure as
defined by Formula 6 below, wherein Z is O, NR.sub.3, or
CR.sub.4R.sub.5 and A comprises a divalent carbon-containing group
having between 1 and 10 carbon atoms. R.sub.3 may be selected from
H and a carbon-containing group having between 1 and 10 carbon
atoms, and R.sub.4 and R.sub.5 are independently selected from H
and a carbon containing group having between 1 and 10 carbon atoms.
The sacrificial agent may comprise a reductone selected from the
group consisting of erythorbic acid, ascorbic acid, reductic acid
(A=CH.sub.2 and Z=CH.sub.2), a salt thereof, and any combination
thereof.
##STR00003##
[0037] In another aspect, the sacrificial agent of the oil recovery
formulation may be a compound that is acidic or is a salt thereof
where the compound lacks a carboxylic acid moiety, a sulfonic acid
moeity, a carboxylate salt moiety, or a sulfonate salt moiety. Such
acidic compounds and salts thereof include phenols, sulfonamides,
and thiols.
[0038] In a further aspect, the oil recovery formulation may
comprise a sacrificial agent wherein the sacrificial agent
comprises a compound having a molecular weight of about 1000 or
less comprising one or more hydroxyl groups. The sacrificial agent
may comprise a compound having one or more hydroxyl groups and have
a molecular weight of 500 or less, or 300 or less, or 200 or less.
The sacrificial agent may comprise a compound containing only one
hydroxyl group, or containing only two hydroxyl groups, or
containing only three hydroxyl groups, or containing only four
hydroxyl groups, or containing only five hydroxyl groups, or
containing only six hydroxyl groups. At least a portion of the
hydroxyl groups in a sacrificial agent compound containing hydroxyl
groups may be enolic hydroxyl groups.
[0039] The sacrificial agent may be comprised of a carbohydrate.
Suitable carbohydrates include monosaccharides and low molecular
weight oligosaccharides having a molecular weight of 1000 or less.
The sacrificial agent may comprise a compound selected from the
group consisting of a monosaccharide, a disaccharide, a
trisaccharide, a tetrasaccharide, a pentasaccharide, and any
combination thereof. The carbohydrate may comprise at least one
reducing sugar or a derivative thereof. Suitable reducing sugars
include, but are not limited to, glucose, glyceraldehyde,
galactose, lactose, maltose, and fructose.
[0040] In another aspect, the oil recovery formulation may comprise
a sacrificial agent that is a compound comprising an oxidizable
functional group. In some embodiments, the sacrificial agent
compound may be a "reducing acid", a salt thereof, or a derivative
thereof. As used herein, a "reducing acid" refers to an acidic
compound, a salt thereof, or a derivative thereof including esters,
lactones, amides, and lactams, that contains a functional group
that may undergo oxidation. The oil recovery formulation may
comprise two or more sacrificial agent compounds wherein the
compounds are a combination of an oxidizable compound and its
oxidation product(s), for example, a combination of erythorbic acid
and dehydroerythorbic acid, salts, and derivatives thereof, or a
combination of ascorbic acid and dehydroascorbic acid, salts, and
derivatives thereof. In embodiments in which one or more of the
sacrificial agent compounds comprise an oxidizable functional
group, the methods described herein may further comprise oxidizing
the sacrificial agent compound(s) after contacting the oil recovery
formulation with the formation.
[0041] The oil recovery formulation also comprises a surfactant in
addition to the sacrificial agent. The surfactant may an anionic
surfactant. The anionic surfactant may be a sulfonate-containing
compound, a sulfate-containing compound, a carboxylate compound, a
phosphate compound, or a blend thereof. The anionic surfactant may
be an alpha olefin sulfonate compound, an internal olefin sulfonate
compound, a branched alkyl benzene sulfonate compound, a propylene
oxide sulfate compound, an ethylene oxide sulfate compound, an
ethylene oxide-propylene oxide sulfate compound, or a blend
thereof. The anionic surfactant may contain from 12 to 30 carbons,
or from 12 to 20 carbons. The surfactant of the oil recovery
formulation may comprise an internal olefin sulfonate compound
containing from 15 to 18 carbons or a propylene oxide sulfate
compound containing from 12 to 15 carbons, or a blend thereof,
where the blend contains a volume ratio of the propylene oxide
sulfate to the internal olefin sulfonate compound of from 1:1 to
10:1.
[0042] The oil recovery formulation further comprises a fluid in
which the surfactant and the sacrificial agent are dispersed. The
fluid may be water or an aqueous brine, and the oil recovery
formulation may be an aqueous mixture of the surfactant and the
sacrificial agent. The fluid may be comprised of water and a
co-solvent. The co-solvent may be a water miscible organic solvent
including water miscible alcohols, glycols, aldehydes, and ketones.
The co-solvent may be methanol, ethanol, isopropanol, isobutyl
alcohol, secondary butyl alcohol, n-butyl alcohol, t-butyl alcohol,
diethylene glycol butyl ether (DGBE), triethylene glycol butyl
ether (TEGBE), sodium dihexyl sulfosuccinate (MA-80), ethylene
glycol, acetone, or a combination thereof.
[0043] The fluid of the oil recovery formulation may be an aqueous
brine solution derived from the petroleum-bearing formation or
formulated to have a salt composition similar to an aqueous
formation brine. In a preferred embodiment, the fluid of the oil
recovery formulation is an aqueous brine solution produced from the
petroleum-bearing formation.
[0044] The concentration of the surfactant in the oil recovery
formulation may range from 0.05 wt. % to 5 wt % of the oil recovery
formulation. The concentration of the surfactant in the oil
recovery formulation may range from 0.1 wt. % to 3 wt. % or from
0.2 wt % to 1 wt. %, or from 0.3 wt. % to 0.7 wt. % of the oil
recovery formulation.
[0045] The concentration of the sacrificial agent in the oil
recovery formulation may range from 0.001 wt. % to 5 wt. % of the
oil recovery formulation. The concentration of the sacrificial
agent in the oil recovery formulation may range from 0.005 wt. % to
1 wt. %, or from 0.01 wt. % to 0.5 wt. %, or from 0.05 wt. % to 0.1
wt. % of the oil recovery formulation.
[0046] The oil recovery formulation comprising the surfactant, the
sacrificial agent, and the fluid may further comprise a polymer
dispersable in the fluid, and preferably soluble in the fluid, and
the oil recovery formulation comprising the surfactant, the
sacrificial agent, the fluid and the polymer may further comprise
an alkali as an aid for dispersing the polymer in the fluid. The
sacrificial agent may be used in conjunction with both SP and ASP
enhanced oil recovery techniques.
[0047] The oil recovery formulation may comprise a polymer selected
from the group consisting of polyacrylamides, partially hydrolyzed
polyacrylamides, polyacrylates, ethylenic co-polymers, biopolymers,
carboxymethylcelloluses, polyvinyl alcohols, polystyrene
sulfonates, polyvinylpyrrolidones, AMPS (2-acrylamide-methyl
propane sulfonate), and combinations thereof. Examples of ethylenic
co-polymers include co-polymers of acrylic acid and acrylamide,
acrylic acid and lauryl acrylate, and lauryl acrylate and
acrylamide. Examples of biopolymers include xanthan gum, guar gum,
alginic acid, and alginate salts.
[0048] The quantity of polymer in the oil recovery formulation, if
any, should be sufficient to drive a mixture of the oil recovery
formulation and petroleum through a petroleum bearing formation.
The quantity of the polymer in the oil recovery formulation may be
sufficient to provide the oil recovery formulation with a dynamic
viscosity at formation temperatures on the same order of magnitude,
or a greater order of magnitude, as the dynamic viscosity of
petroleum in a petroleum-bearing formation at formation
temperatures so the oil recovery formulation may push a mixture of
oil recovery formulation and petroleum through the formation. The
quantity of the polymer in the oil recovery formulation may be
sufficient to provide the oil recovery formulation with a dynamic
viscosity of at least 10 mPa s (10 cP), or at least 100 mPa s (100
cP), or at least 500 mPa s (500 cP), or at least 1000 mPa s (1000
cP) at 25.degree. C. or at a temperature within a formation
temperature range. The concentration of polymer in the oil recovery
formulation may be from 250 ppm to 5000 ppm, or from 500 ppm to
2500 ppm, or from 1000 to 2000 ppm.
[0049] The molecular weight average of the polymer in the oil
recovery formulation should be sufficient to provide sufficient
viscosity to the oil recovery formulation to drive petroleum or a
mixture of petroleum and the oil recovery formulation through the
formation. The polymer may have a molecular weight average of at
least 10000 daltons, or at least 50000 daltons, or at least 100000
daltons. The polymer may have a molecular weight average of from
10000 to 20000000 daltons, or from 100000 to 1000000 daltons.
[0050] The oil recovery formulation may comprise an alkali.
Suitable alkali compounds include lithium hydroxide, sodium
hydroxide, potassium hydroxide, lithium carbonate, sodium
carbonate, potassium carbonate, lithium bicarbonate, sodium
bicarbonate, potassium bicarbonate, lithium silicate, lithium
phosphate, sodium silicate, sodium phosphate, potassium silicate,
and potassium phosphate. The oil recovery formulation may comprise
from 0.001 wt. % to 5 wt. % of the alkali, or from 0.005 wt. % to 1
wt. % of the alkali, or from 0.01 wt. % to 0.5 wt. % of the
alkali.
[0051] In one aspect, the present invention is directed to an oil
recovery formulation composition. The oil recovery formulation
composition comprises a fluid, a surfactant dispersed in the fluid,
and a sacrificial agent dispersed in the fluid, where the
sacrificial agent is selected from the group consisting of a
compound comprising a single carboxylic acid, carboxylic acid
derivative, or carboxylate salt moiety, as described above; a
compound comprising a stabilized enol or that is enolizable, as
described above; a compound having a molecular weight of about 1000
or less comprising one or more hydroxyl groups, as described above;
a "reducing acid", as described above; a compound that is acidic or
is a salt thereof where the compound lacks a carboxylic acid
moiety, a sulfonic acid moeity, a carboxylate salt moiety, or a
sulfonate salt moiety and is selected from the group consisting of
a phenol, a sulfonamide, a thiol, and combinations thereof. The
fluid may be water. The surfactant may be an anionic surfactant,
and the anionic surfactant may be selected from the group
consisting of an alpha olefin sulfonate compound, an internal
olefin sulfonate compound, a branched alkyl benzene sulfonate
compound, a propylene oxide sulfate compound, or a blend thereof.
The oil recovery formulation composition may further comprise a
polymer selected from the group consisting of polyacrylamides,
partially hydrolyzed polyacrylamides, polyacrylates, ethylenic
co-polymers, biopolymers, carboxymethylcelloluses, polyvinyl
alcohols, polystyrene sulfonates, polyvinylpyrrolidones, AMPS
(2-acrylamide-methyl propane sulfonate), and combinations thereof,
as described above. The oil recovery formulation composition may
further comprise an alkali, as described above. The alkali compound
may be selected from the group consisting of lithium hydroxide,
sodium hydroxide, potassium hydroxide, lithium carbonate, sodium
carbonate, potassium carbonate, lithium bicarbonate, sodium
bicarbonate, potassium bicarbonate, lithium silicate, lithium
phosphate, sodium silicate, sodium phosphate, potassium silicate,
potassium phosphate, and mixtures thereof.
[0052] The oil recovery formulation composition may contain from
0.001 wt. % to 5 wt. %, or from 0.01 wt. % to 0.5 wt. % of the
sacrificial agent, as described above, and may contain from 0.05
wt. % to 5 wt. %, or from 0.1 wt. % to 3 wt. % of the surfactant as
described above, where the balance of the oil recovery formulation
is a fluid in which the sacrificial agent and the surfactant are
dispersed, and preferably dissolved, where the fluid may be water.
The oil recovery formulation composition may further comprise from
250 ppm to 5000 ppm, or from 500 ppm to 2500 ppm, of the polymer,
as described above. The oil recovery formulation may further
comprise from 0.001 wt. % to 5 wt. %, or from 0.01 wt. % to 0.5 wt.
% of the alkali, as described above.
[0053] In the method of the present invention the oil recovery
formulation is introduced into a petroleum-bearing formation, and
the system of the present invention includes a petroleum-bearing
formation. The petroleum-bearing formation comprises petroleum that
may be separated and produced from the formation after contact and
mixing with the oil recovery formulation. The petroleum of the
petroleum-bearing formation may be a heavy oil containing at least
25 wt. %, or at least 30 wt. %, or at least 35 wt. %, or at least
40 wt. % of hydrocarbons having a boiling point of at least
538.degree. C. (1000.degree. F.) as determined in accordance with
ASTM Method D5307. The heavy oil may have an asphaltene content of
at least at least 5 wt. %, or at least 10 wt. %, or at least 15 wt.
%, where "asphaltene" as used herein refers to a hydrocarbon
compound that is insoluble in n-heptane and in soluble in toluene.
The petroleum contained in the petroleum-bearing formation may be
an intermediate weight oil or a relatively light oil containing
less than 25 wt. %, or less than 20 wt. %, or less than 15 wt. %,
or less than 10 wt. %, or less than 5 wt. % of hydrocarbons having
a boiling point of at least 538.degree. C. (1000.degree. F.). The
intermediate weight oil or light oil may have an asphaltene content
of less than 5 wt. %.
[0054] The petroleum contained in the petroleum-bearing formation
may have a dynamic viscosity under formation conditions (in
particular, at temperatures within the temperature range of the
formation) of at least 1 mPa s (1 cP), or at least 10 mPa s (10
cP), or at least 100 mPa s (100 cP), or at least 1000 mPa s (1000
cP), or at least 10000 mPa s (10000 cP). The petroleum contained in
the petroleum-bearing formation may have a dynamic viscosity under
formation temperature conditions of from 1 to 10000000 mPa s (1 to
10000000 cP).
[0055] The petroleum-bearing formation may be a subterranean
formation. The subterranean formation may be comprised of one or
more porous matrix materials selected from the group consisting of
a porous mineral matrix, a porous rock matrix, and a combination of
a porous mineral matrix and a porous rock matrix, where the porous
matrix material may be located beneath an overburden at a depth
ranging from 50 meters to 6000 meters, or from 100 meters to 4000
meters, or from 200 meters to 2000 meters under the earth's
surface. The subterranean formation may be a subsea subterranean
formation.
[0056] The porous matrix material may be a consolidated matrix
material in which at least a majority, and preferably substantially
all, of the rock and/or mineral that forms the matrix material is
consolidated such that the rock and/or mineral forms a mass in
which substantially all of the rock and/or mineral is immobile when
petroleum, the oil recovery formulation, water, or other fluid is
passed therethrough. Preferably at least 95 wt. % or at least 97
wt. %, or at least 99 wt. % of the rock and/or mineral is immobile
when petroleum, the oil recovery formulation, water, or other fluid
is passed therethrough so that any amount of rock or mineral
material dislodged by the passage of the petroleum, oil recovery
formulation, water, or other fluid is insufficient to render the
formation impermeable to the flow of the oil recovery formulation,
petroleum, water, or other fluid through the formation. The porous
matrix material may be an unconsolidated matrix material in which
at least a majority, or substantially all, of the rock and/or
mineral that forms the matrix material is unconsolidated. The
formation may have a permeability of from 0.0001 to 15 Darcys, or
from 0.001 to 1 Darcy. The rock and/or mineral porous matrix
material of the formation may be comprised of sandstone and/or a
carbonate selected from dolomite, limestone, and mixtures
thereof--where the limestone may be microcrystalline or crystalline
limestone and/or chalk.
[0057] Petroleum in the petroleum-bearing formation may be located
in pores within the porous matrix material of the formation. The
petroleum in the petroleum-bearing formation may be immobilized in
the pores within the porous matrix material of the formation, for
example, by capillary forces, by interaction of the petroleum with
the pore surfaces, by the viscosity of the petroleum, or by
interfacial tension between the petroleum and water in the
formation.
[0058] The petroleum-bearing formation may also be comprised of
water, which may be located in pores within the porous matrix
material. The water in the formation may be connate water, water
from a secondary or tertiary oil recovery process water-flood, or a
mixture thereof. The water in the petroleum-bearing formation may
be positioned to immobilize petroleum within the pores. Contact of
the oil recovery formulation with the petroleum in the formation
may mobilize the petroleum in the formation for production and
recovery from the formation by freeing at least a portion of the
petroleum from pores within the formation.
[0059] In some embodiments, the petroleum-bearing formation may
comprise unconsolidated sand and water. The petroleum-bearing
formation may be an oil sand formation. In some embodiments, the
petroleum may comprise between about 1 wt. % and about 16 wt. % of
the oil/sand/water mixture, the sand may comprise between about 80
wt. % and about 85 wt. % of the oil/sand/water mixture, and the
water may comprise between about 1 wt. % and about 16 wt. % of the
oil/sand water mixture. The sand may be coated with a layer of
water with the petroleum being located in the void space around the
wetted sand grains. Optionally, the petroleum-bearing formation may
also include a gas, such as methane or air, for example.
[0060] Referring now to FIG. 1, a system 200 of the present
invention for practicing a method of the present invention is
shown. The system includes a first well 201 and a second well 203
extending into a petroleum-bearing formation 205 such as described
above. The petroleum-bearing formation 205 may be comprised of one
or more formation portions 207, 209, and 211 formed of porous
material matrices, such as described above, located beneath an
overburden 213. An oil recovery formulation comprising a fluid,
preferably water, a surfactant, and a sacrificial agent as
described above, and optionally comprising a polymer and/or an
alkali as described above, is provided. The oil recovery
formulation may be provided from an oil recovery formulation
storage facility 215 fluidly operatively coupled to a first
injection/production facility 217 via conduit 219. First
injection/production facility 217 may be fluidly operatively
coupled to the first well 201, which may be located extending from
the first injection/production facility 217 into the
petroleum-bearing formation 205. The oil recovery formulation may
flow from the first injection/production facility 217 through the
first well to be introduced into the formation 205, for example in
formation portion 209, where the first injection/production
facility 217 and the first well, or the first well itself,
include(s) a mechanism for introducing the oil recovery formulation
into the formation. Alternatively, the oil recovery formulation may
flow from the oil recovery formulation storage facility 215
directly to the first well 201 for injection into the formation
205, where the first well comprises a mechanism for introducing the
oil recovery formulation into the formation. The mechanism for
introducing the oil recovery formulation into the formation 205 via
the first well 201--located in the first injection/production
facility 217, the first well 201, or both--may be comprised of a
pump 221 for delivering the oil recovery formulation to
perforations or openings in the first well through which the oil
recovery formulation may be introduced into the formation.
[0061] The oil recovery formulation may be introduced into the
formation 205, for example by injecting the oil recovery
formulation into the formation through the first well 201 by
pumping the oil recovery formulation through the first well and
into the formation. The pressure at which the oil recovery
formulation is introduced into the formation may range from the
instantaneous pressure in the formation up to, but not including,
the fracture pressure of the formation. The pressure at which the
oil recovery formulation may be injected into the formation may
range from 20% to 95%, or from 40% to 90%, of the fracture pressure
of the formation. Alternatively, the oil recovery formulation may
also be injected into the formation at a pressure of at least the
fracture pressure of the formation, where the oil recovery
formulation is injected under fracturing conditions.
[0062] The volume of oil recovery formulation introduced into the
formation 205 via the first well 201 may range from 0.001 to 5 pore
volumes, or from 0.01 to 2 pore volumes, or from 0.1 to 1 pore
volumes, or from 0.2 to 0.6 pore volumes, where the term "pore
volume" refers to the volume of the formation that may be swept by
the oil recovery formulation between the first well 201 and the
second well 203. The pore volume may be readily be determined by
methods known to a person skilled in the art, for example by
modelling studies or by injecting water having a tracer contained
therein through the formation 205 from the first well 201 to the
second well 203.
[0063] As the oil recovery formulation is introduced into the
formation 205, the oil recovery formulation spreads into the
formation as shown by arrows 223. Upon introduction to the
formation 205, the oil recovery formulation contacts and forms a
mixture with a portion of the petroleum in the formation. The oil
recovery formulation may mobilize the petroleum in the formation
upon contacting and mixing with the petroleum and water in the
formation. The oil recovery formulation may mobilize the petroleum
in the formation upon contacting and mixing with the petroleum, for
example, by reducing capillary forces retaining the petroleum in
pores in the formation, by reducing the wettability of the
petroleum on pore surfaces in the formation, by reducing the
interfacial tension between petroleum and water in the formation,
and/or by forming a microemulsion with petroleum and water in the
formation.
[0064] Upon introduction of the oil recovery formulation into the
formation, the sacrificial agent may interact with the formation,
the water in the formation, petroleum in the formation and/or the
surfactant to inhibit loss of the surfactant within the formation.
The sacrificial agent may temporarily or permanently bind to
surfaces within the formation, for example to mineral or rock
surfaces within the formation, and/or the sacrificial agent may
temporarily or permanently bind to ions, preferably divalent
cations, in the water within the formation to inhibit or prevent
the loss of the surfactant within the formation.
[0065] The mobilized mixture of the oil recovery formulation and
petroleum and any unmixed oil recovery formulation may be pushed
across the formation 205 from the first well 201 to the second well
203 by further introduction of more oil recovery formulation into
the formation. The oil recovery formulation may be designed to
displace the mobilized mixture of the oil recovery formulation and
petroleum through the formation for production at the second well
203. As described above, the oil recovery formulation may contain a
polymer, wherein the oil recovery formulation comprising the
polymer may have a viscosity of at least the same order of
magnitude as the viscosity of the petroleum in the formation under
formation temperature conditions, and preferably at least one order
of magnitude greater than the viscosity of the petroleum in the
formation at formation temperature conditions, so the oil recovery
formulation may drive the mobilized mixture of oil recovery
formulation and petroleum across the formation while inhibiting
fingering of the mobilized petroleum/oil recovery formulation
through the driving plug of oil recovery formulation.
[0066] Petroleum may be mobilized for production from the formation
205 via the second well 203 by introduction of the oil recovery
formulation into the formation, where the mobilized petroleum is
driven through the formation for production from the second well as
indicated by arrows 229 by introduction of the oil recovery
formulation into the formation via the first well 201. The
petroleum mobilized for production from the formation 205 may
include the mobilized petroleum/oil recovery formulation mixture.
Water and/or gas may also be mobilized for production from the
formation 205 via the second well 203 by introduction of the oil
recovery formulation into the formation via the first well 201.
[0067] After introduction of the oil recovery formulation into the
formation 205 via the first well 201, petroleum may be recovered
and produced from the formation via the second well 203. The oil
recovery formulation, or a portion thereof, may also be recovered
and produced from the formation, optionally in conjunction with the
petroleum. Portions of the oil recovery formulation may be
recovered separately from other portions of the oil recovery
formulation. For example, the surfactant or the sacrificial agent
of the oil recovery formulation may be recovered separately from
the fluid of the oil recovery formulation, for example, the
surfactant may be recovered in the petroleum produced from the
formation and not in water that formed a portion of the oil
recovery formulation.
[0068] The system of the present invention may include a mechanism
located at the second well for recovering and producing the
petroleum from the formation 205 subsequent to introduction of the
oil recovery formulation into the formation, and may include a
mechanism located at the second well for recovering and producing
the oil recovery formulation or a portion thereof and/or gas from
the formation subsequent to introduction of the oil recovery
formulation into the formation. The mechanism located at the second
well 203 for recovering and producing the petroleum, and optionally
for recovering and producing the oil recovery formulation, or a
portion thereof, and/or gas may be comprised of a pump 233, which
may be located in a second injection/production facility 231 and/or
within the second well 203. The pump 233 may draw the petroleum,
and optionally the oil recovery formulation or a portion thereof
and/or gas from the formation 205 through perforations in the
second well 203 to deliver the petroleum, and optionally the oil
recovery formulation or a portion thereof and/or gas, to the second
injection/production facility 231.
[0069] Alternatively, the mechanism for recovering and producing
the petroleum--and optionally the oil recovery formulation or a
portion thereof and/or gas--from the formation 205 may be comprised
of a compressor 234 that may be located in the second
injection/production facility 231. The compressor 234 may be
fluidly operatively coupled to a gas storage tank 241 via conduit
236, and may compress gas from the gas storage tank for injection
into the formation 205 through the second well 203. The compressor
may compress the gas to a pressure sufficient to drive production
of petroleum--and optionally the oil recovery formulation or a
portion thereof and/or gas--from the formation via the second well
203, where the appropriate pressure may be determined by
conventional methods known to those skilled in the art. The
compressed gas may be injected into the formation from a different
position on the second well 203 than the well position at which the
petroleum--and optionally the oil recovery formulation or a portion
thereof and/or gas--are produced from the formation, for example,
the compressed gas may be injected into the formation at formation
portion 207 while petroleum, oil recovery formulation, and/or gas
are produced from the formation at formation portion 209.
[0070] Petroleum, optionally in a mixture with the oil recovery
formulation or a portion thereof and/or gas may be drawn from the
formation 205 as shown by arrows 229 and produced up the second
well 203 to the second injection/production facility 231. The
petroleum may be separated from the oil recovery formulation, or a
portion thereof, and/or gas in a separation unit 235 located in the
second injection/production facility 231 and operatively fluidly
coupled to the mechanism 233 for recovering and producing petroleum
and, optionally, the oil recovery formulation, or a portion
thereof, and/or gas, from the formation. The separation unit 235
may be comprised of a conventional liquid-gas separator for
separating gas from the petroleum and the oil recovery formulation;
and a conventional hydrocarbon-water separator including a
demulsification unit for separating the petroleum from the oil
recovery formulation.
[0071] The separated produced petroleum may be provided from the
separation unit 235 of the second injection/production facility 231
to a petroleum storage tank 237, which may be fluidly operatively
coupled to the separation unit 235 of the second
injection/production facility by conduit 239. The separated gas, if
any, may be provided from the separation unit 235 of the second
injection/production facility 231 to the gas storage tank 241,
which may be fluidly operatively coupled to the separation unit 235
of the second injection/production facility 231 by conduit 243.
[0072] The separated produced oil recovery formulation may be
provided from the separation unit 235 of the second
injection/production facility 231 to the oil recovery formulation
storage unit 215, which may be fluidly operatively coupled to the
separation unit 235 of the second injection/production facility 231
by conduit 245. Alternatively, the separated oil recovery
formulation may be provided from the separation unit 235 of the
second injection/production facility 231 to the injection mechanism
221 via conduit 238 for re-injection into the formation 205 through
the first well 201 for further mobilization and recovery of
petroleum from the formation. Alternatively, the separated oil
recovery formulation may be provided from the separation unit 235
to an injection mechanism such as pump 251 in the second
injection/production facility 231 via conduit 240 for re-injection
into the formation 205 through the second well 203, optionally
together with fresh oil recovery formulation.
[0073] In an embodiment of a system and a method of the present
invention, the first well 201 may be used for injecting the oil
recovery formulation into the formation 205 and the second well 203
may be used to produce petroleum from the formation as described
above for a first time period, and the second well 203 may be used
for injecting the oil recovery formulation into the formation 205
to mobilize the petroleum in the formation and drive the mobilized
petroleum across the formation to the first well and the first well
201 may be used to produce petroleum from the formation for a
second time period, where the second time period is subsequent to
the first time period. The second injection/production facility 231
may comprise a mechanism such as pump 251 that is fluidly
operatively coupled the oil recovery formulation storage facility
215 by conduit 253, and optionally fluidly operatively coupled to
the separation units 235 and 259 by conduits 240 and 242,
respectively, to receive produced oil recovery formulation
therefrom, and that is fluidly operatively coupled to the second
well 203 to introduce the oil recovery formulation into the
formation 205 via the second well. The first injection/production
facility 217 may comprise a mechanism such as pump 257 or
compressor 258 for production of petroleum, and optionally the oil
recovery formulation and/or gas from the formation 205 via the
first well 201. The first injection/production facility 217 may
also include a separation unit 259 for separating produced
petroleum, produced oil recovery formulation and/or gas. The
separation unit 259 may be comprised of a conventional liquid-gas
separator for separating gas from the produced petroleum and the
produced oil recovery formulation; and a conventional
hydrocarbon-water separator for separating the produced petroleum
from the produced oil recovery formulation, where the
hydrocarbon-water separator may comprise a demulsifier. The
separation unit 259 may be fluidly operatively coupled to: the
petroleum storage tank 237 by conduit 261 for storage of produced
petroleum in the petroleum storage tank; and the gas storage tank
241 by conduit 265 for storage of produced gas in the gas storage
tank.
[0074] The separation unit 259 may be fluidly operatively coupled
to the oil recovery formulation storage facility 215 by conduit 263
for storage of the produced oil recovery formulation in the oil
recovery formulation storage facility 215. The separation unit 259
may be fluidly operatively coupled to either the injection
mechanism 221 of the first injection/production facility 217 for
injecting the produced oil recovery formulation into the formation
205 through the first well 201 or the injection mechanism 251 of
the second injection/production facility 231 for injecting the
produced oil recovery formulation into the formation through the
second well 203 by conduits 242 and 244, respectively.
[0075] The first well 201 may be used for introducing the oil
recovery formulation into the formation 205 and the second well 203
may be used for producing petroleum and, optionally the oil
recovery formulation, from the formation for a first time period;
then the second well 203 may be used for introducing the oil
recovery formulation into the formation 205 and the first well 201
may be used for producing petroleum, and optionally the oil
recovery formulation, from the formation for a second time period;
where the first and second time periods comprise a cycle. Multiple
cycles may be conducted which include alternating the first well
201 and the second well 203 between introducing the oil recovery
formulation into the formation 205 and producing petroleum, and
optionally the oil recovery formulation, from the formation, where
one well is introducing and the other is producing for the first
time period, and then they are switched for a second time period. A
cycle may be from about 12 hours to about 1 year, or from about 3
days to about 6 months, or from about 5 days to about 3 months.
[0076] Referring now to FIG. 2, an array of wells 300 is
illustrated. Array 300 includes a first well group 302 (denoted by
horizontal lines) and a second well group 304 (denoted by diagonal
lines). In some embodiments of the system and method of the present
invention, the first well of the system and method described above
may include multiple first wells depicted as the first well group
302 in the array 300, and the second well of the system and method
described above may include multiple second wells depicted as the
second well group 304 in the array 300.
[0077] Each well in the first well group 302 may be a horizontal
distance 330 from an adjacent well in the first well group 302. The
horizontal distance 330 may be from about 5 to about 1000 meters,
or from about 10 to about 500 meters, or from about 20 to about 250
meters, or from about 30 to about 200 meters, or from about 50 to
about 150 meters, or from about 90 to about 120 meters, or about
100 meters. Each well in the first well group 302 may be a vertical
distance 332 from an adjacent well in the first well group 302. The
vertical distance 332 may be from about 5 to about 1000 meters, or
from about 10 to about 500 meters, or from about 20 to about 250
meters, or from about 30 to about 200 meters, or from about 50 to
about 150 meters, or from about 90 to about 120 meters, or about
100 meters.
[0078] Each well in the second well group 304 may be a horizontal
distance 336 from an adjacent well in the second well group 304.
The horizontal distance 336 may be from about 5 to about 1000
meters, or from about 10 to about 500 meters, or from about 20 to
about 250 meters, or from about 30 to about 200 meters, or from
about 50 to about 150 meters, or from about 90 to about 120 meters,
or about 100 meters. Each well in the second well group 304 may be
a vertical distance 338 from an adjacent well in the second well
group 304. The vertical distance 338 may be from about 5 to about
1000 meters, or from about 10 to about 500 meters, or from about 20
to about 250 meters, or from about 30 to about 200 meters, or from
about 50 to about 150 meters, or from about 90 to about 120 meters,
or about 100 meters.
[0079] Each well in the first well group 302 may be a distance 334
from the adjacent wells in the second well group 304. Each well in
the second well group 304 may be a distance 334 from the adjacent
wells in first well group 302. The distance 334 may be from about 5
to about 1000 meters, or from about 10 to about 500 meters, or from
about 20 to about 250 meters, or from about 30 to about 200 meters,
or from about 50 to about 150 meters, or from about 90 to about 120
meters, or about 100 meters.
[0080] Each well in the first well group 302 may be surrounded by
four wells in the second well group 304. Each well in the second
well group 304 may be surrounded by four wells in the first well
group 302.
[0081] In some embodiments, the array of wells 300 may have from
about 10 to about 1000 wells, for example from about 5 to about 500
wells in the first well group 302, and from about 5 to about 500
wells in the second well group 304.
[0082] In some embodiments, the array of wells 300 may be seen as a
top view with first well group 302 and the second well group 304
being vertical wells spaced on a piece of land. In some
embodiments, the array of wells 300 may be seen as a
cross-sectional side view of the formation with the first well
group 302 and the second well group 304 being horizontal wells
spaced within the formation.
[0083] Referring now to FIG. 3, an array of wells 400 is
illustrated. Array 400 includes a first well group 402 (denoted by
horizontal lines) and a second well group 404 (denoted by diagonal
lines). The array 400 may be an array of wells as described above
with respect to array 300 in FIG. 3. In some embodiments of the
system and method of the present invention, the first well of the
system and method described above may include multiple first wells
depicted as the first well group 402 in the array 400, and the
second well of the system and method described above may include
multiple second wells depicted as the second well group 404 in the
array 400.
[0084] The oil recovery formulation may be injected into first well
group 402 and petroleum, and optionally the oil recovery
formulation, may be recovered and produced from the second well
group 404. As illustrated, the oil recovery formulation may have an
injection profile 406, and petroleum, and optionally the oil
recovery formulation, may be produced from the second well group
404 having a petroleum recovery profile 408.
[0085] The oil recovery formulation may be injected into the second
well group 404 and petroleum, and optionally the oil recovery
formulation, may be produced from the first well group 402. As
illustrated, the oil recovery formulation may have an injection
profile 408, and petroleum, and optionally the oil recovery
formulation, may be produced from the first well group 402 having a
petroleum recovery profile 406.
[0086] The first well group 402 may be used for injecting the oil
recovery formulation and the second well group 404 may be used for
producing petroleum, and optionally the oil recovery formulation,
from the formation for a first time period; then second well group
404 may be used for injecting the oil recovery formulation and the
first well group 402 may be used for producing petroleum, and
optionally the oil recovery formulation, from the formation for a
second time period, where the first and second time periods
comprise a cycle. In some embodiments, multiple cycles may be
conducted which include alternating first and second well groups
402 and 404 between injecting the oil recovery formulation and
producing petroleum, and optionally the oil recovery formulation,
from the formation, where one well group is injecting and the other
is producing for a first time period, and then they are switched
for a second time period.
[0087] To facilitate a better understanding of the present
invention, the following examples of certain aspects of some
embodiments are given. In no way should the following examples be
read to limit, or define, the scope of the invention.
Example 1
[0088] Erythorbic acid was added at 0.1 wt. % concentration to an
ASP fluid containing 2 wt. % Na.sub.2CO.sub.3, 1.75 wt. % NaCl,
0.48 wt. % of a C.sub.12-13-7PO (propylene oxide) sulfate
surfactant, 0.12 wt. % of a C.sub.15-18 internal olefin sulfonate
surfactant, and 10 ppm of a non-interacting cobalt tracer. The
fluid was then passed through a Berea core in the presence of a
formation brine (formation brine: 14.8 g/L NaCl, 0.043 g/L
CaCl.sub.2, 0.073 g/L MgCl.sub.2) and both in the presence and the
absence of petroleum, and the retention of the various fluid
components was determined. A control test was performed with a
fluid lacking erythorbic acid. FIGS. 4 and 5 show illustrative
retention plots of various fluid components in the presence and
absence of erythorbic acid, respectively. As shown in FIG. 4, when
erythorbic acid was present, the surfactant trailed the tracer only
slightly. When erythorbic acid was present, the surfactant trailed
the cobalt tracer by 0.03 pore volumes (PV) in the presence of
petroleum and by 0.04 PV in the absence of petroleum. This degree
of retention corresponded to 3.6 mg of retained surfactant per 100
g of core in the absence of petroleum. In contrast, as shown in
FIG. 5, when erythorbic acid was absent, the surfactant was much
more strongly retained. When erythorbic acid was absent, the
surfactant trailed the cobalt tracer by 0.31 PV in the presence of
petroleum and by 0.22 PV in the absence of petroleum. This degree
of retention corresponded to 20 mg of retained surfactant per 100 g
of core in the absence of petroleum. FIG. 6 shows an illustrative
production chart observed in the presence of erythorbic acid.
Example 2
[0089] The effectiveness of ascorbic acid, glucose (monohydrate),
EDTA, sodium acetate, and erythorbic acid as sacrificial agents for
inhibiting surfactant adsorption in sandstone was determined when
used in a pre-flush solution prior to contacting sandstone with a
surfactant. Four pre-flush solutions were prepared by mixing a
brine solution containing 14.8 g/L NaCl, 0.043 g/L
CaCl.sub.2.2H.sub.2O, and 0.073 g/L MgCl.sub.2.6H.sub.2O with 500
ppm of ascorbic acid, glucose (monohydrate), EDTA, and erythorbic
acid, respectively, as a sacrificial agent. A fifth pre-flush
solution was prepared by mixing the same brine solution with 183
ppm of sodium acetate as a sacrificial agent. For each of the
pre-flush solutions, a Bandera brown sandstone core was flushed
with CO.sub.2 to remove air in the core and then was saturated with
a brine solution containing 14.8 g/L NaCl, 0.043 g/L
CaCl.sub.2.2H.sub.2O, and 0.073 g/L MgCl.sub.2.6H.sub.2O. The core
was then injected with 3.5 pore volumes of the pre-flush solution
followed by injection of a surfactant slug of 3 pore volumes, where
the surfactant slug contained 0.48 wt. % of a C.sub.12-13.sup.7PO
(propylene oxide) sulfate surfactant, 0.12 wt. % of a C.sub.15-18
internal olefin sulfonate surfactant, and 10 ppm of a
non-interacting cobalt tracer in an aqueous brine containing 3.45
wt. % NaCl. After the injection of the surfactant slug, the core
was injected with 3 pore volumes of an aqueous brine containing
3.45 wt. % NaCl. A control was also conducted where a Bandera brown
sandstone core saturated with a brine solution containing 14.8 g/L
NaCl, 0.043 g/L CaCl.sub.2.2H.sub.2O, and 0.073 g/L
MgCl.sub.2.6H.sub.2O was injected with 3 pore volumes of the
surfactant slug as described above followed by 3 pore volumes of
aqueous brine containing 3.45 wt. % NaCl with no injection of a
pre-flush solution.
[0090] Retention of the surfactant in the core was measured by
calculating the difference in pore volumes after injection of the
surfactant between observed cobalt tracer elution (50%) from the
core and the observed surfactant elution (50%) from the core. The
calculated surfactant lag and corresponding calculated amount of
surfactant adsorbed to the core (wt./wt.) for each pre-flush
solution and the control is shown in Table 1 below.
TABLE-US-00001 TABLE 1 Preflush Surfactant lag (PV) Adsorption
(mg/100 g core) Control (no pre-flush) 1.35 97 Erythorbic acid 0.91
54 Ascorbic acid 0.79 51 Glucose 1.18 77 EDTA 1.16 77 Na-acetate
1.24 81
[0091] As shown in Table 1, all of the sacrificial agent pre-flush
solutions showed a positive effect for reducing surfactant
retention in the core relative to the control.
[0092] The present invention is well adapted to attain the ends and
advantages mentioned as well as those that are inherent therein.
The particular embodiments disclosed above are illustrative only,
as the present invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. Furthermore, no limitations
are intended to the details of construction or design herein shown,
other than as described in the claims below. While systems and
methods are described in terms of "comprising," "containing," or
"including" various components or steps, the compositions and
methods can also "consist essentially of" or "consist of" the
various components and steps. Whenever a numerical range with a
lower limit and an upper limit is disclosed, any number and any
included range falling within the range is specifically disclosed.
In particular, every range of values (of the form, "from a to b,"
or, equivalently, "from a-b") disclosed herein is to be understood
to set forth every number and range encompassed within the broader
range of values. Whenever a numerical range having a specific lower
limit only, a specific upper limit only, or a specific upper limit
and a specific lower limit is disclosed, the range also includes
any numerical value "about" the specified lower limit and/or the
specified upper limit. Also, the terms in the claims have their
plain, ordinary meaning unless otherwise explicitly and clearly
defined by the patentee. Moreover, the indefinite articles "a" or
"an", as used in the claims, are defined herein to mean one or more
than one of the element that it introduces.
* * * * *