U.S. patent number 3,554,286 [Application Number 04/834,864] was granted by the patent office on 1971-01-12 for recovery of hydrocarbons from subterranean hydrocarbon-bearing formations.
This patent grant is currently assigned to Texaco Inc.. Invention is credited to David G. Feuerbacher, Thomas E. Sample, Jr..
United States Patent |
3,554,286 |
Feuerbacher , et
al. |
January 12, 1971 |
RECOVERY OF HYDROCARBONS FROM SUBTERRANEAN HYDROCARBON-BEARING
FORMATIONS
Abstract
A process for the recovery of hydrocarbons from subterranean
hydrocarbon-bearing formations by the treatment of the formation
with an aqueous medium containing a base and a substituted
nitrobenzene.
Inventors: |
Feuerbacher; David G.
(Bellaire, TX), Sample, Jr.; Thomas E. (Houston, TX) |
Assignee: |
Texaco Inc. (New York,
NY)
|
Family
ID: |
25268007 |
Appl.
No.: |
04/834,864 |
Filed: |
June 19, 1969 |
Current U.S.
Class: |
166/266; 166/400;
166/272.4; 208/390 |
Current CPC
Class: |
C09K
8/58 (20130101) |
Current International
Class: |
C09K
8/58 (20060101); E21b 043/22 (); E21b 043/24 () |
Field of
Search: |
;166/266,267,265,268,274,275,272,263,305,271 ;208/11 ;299/7
;252/8.55D |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Novosad; Stephen J.
Claims
We claim:
1. A process for recovering hydrocarbons from a subterranean
hydrocarbon-bearing formation which comprises contacting said
formation with an aqueous medium containing a base and a
substituted nitrobenzene in amounts sufficient to reduce the
absorptive capacity of said formation for said hydrocarbons and
enhance the mobility thereof, thereby forming an emulsion of said
hydrocarbons in said formation and said aqueous medium, recovering
the emulsion thus formed, and separating hydrocarbons from said
emulsion.
2. The process of claim 1 wherein said base is selected from the
group consisting of the hydroxides of sodium, potassium, ammonium
and mixtures thereof.
3. The process of claim 2, wherein said base is contained in the
aqueous medium in concentrations in the range of from about 0.001N
to 1.ON.
4. The process of claim 1 wherein the substituents of said
substituted nitrobenzene are selected from the group consisting of
methyl, ethyl, methoxy, ethoxy, and hydroxy and combinations
thereof.
5. The process of claim 1 wherein said substituted nitrobenzene is
selected from the group consisting of o-nitroanisole,
o-nitrotoluene, o-nitrophenol nitrated mixed (m,p) cresols and
mixtures thereof.
6. The process of claim 1 wherein said substituted nitrobenzene is
in the range from about 500 ppm to 5000 ppm.
7. The process of claim 1 including the addition of a nonionic
emulsifying agent to said aqueous medium.
8. The process of claim 1 including the addition of a solubilizing
agent to said aqueous medium.
9. A process for recovering hydrocarbons from a subterranean
hydrocarbon-bearing formation penetrated by an injection well and a
production well, which comprises injecting into said formation
through said injection well an aqueous medium containing a base and
a substituted nitrobenzene in amounts sufficient to reduce the
absorptive capacity of said formation for said hydrocarbons and
enhance the mobility thereof, and thereafter injecting an aqueous
drive medium into said formation through said injection well and
driving the same toward said production well.
10. The process of claim 9, wherein said base is selected from the
group consisting of the hydroxides of sodium, potassium, ammonium
and mixtures thereof.
11. The process of claim 10, wherein said base is contained in the
aqueous medium in concentrations in the range of from about 0.001N
to 1.ON.
12. The process of claim 9 wherein the substituents of said
substituted nitrobenzene are selected from the group consisting of
methyl, ethyl, methoxy, ethoxy, and hydroxy and combinations
thereof.
13. The process of claim 9 wherein said substituted nitrobenzene is
selected from the group consisting of o-nitroanisole,
o-nitrotoluene, o-nitrophenol nitrated mixed (m,p) cresols and
mixtures thereof.
14. The process of claim 9 wherein said substituted nitrobenzene is
in the range from about 500 ppm to 5000 ppm.
15. The process of claim 9 wherein said aqueous drive medium is
H.sub.2 O.
16. The process of claim 15 wherein the H.sub.2 O is water, steam,
and mixtures thereof, the temperatures thereof being fixed by
optimum conditions of operation.
17. The process of claim 9 including the addition of a nonionic
emulsifying agent to said aqueous medium.
18. The process of claim 9 including the addition of a solubilizing
agent to said aqueous medium.
19. A process for recovering hydrocarbons from a
hydrocarbon-bearing sand matrix having heretofore undergone mining
processing, which comprises contacting said hydrocarbonbearing sand
matrix with an aqueous medium containing a base and a substituted
nitrobenzene thereby forming an emulsion of said hydrocarbons in
said sand matrix and said aqueous medium, recovering the emulsion
thus formed, and separating hydrocarbons from said emulsion.
20. The process of claim 19 wherein said base is selected from the
group consisting of the hydroxides of sodium, potassium, ammonium
and mixtures thereof.
21. The process of Claim 20 wherein said base is contained in the
aqueous carrier in concentrations in the range of from about 0.001N
to 1.ON.
22. The process of claim 19 wherein the substituents of said
substituted nitrobenzene are selected from the group consisting of
methyl, ethyl, methoxy, ethoxy, and hydroxy and combinations
thereof.
23. The process of claim 19 wherein said substituted nitrobenzene
is selected from the group consisting of o-nitroanisole,
o-nitrotoluene, o-nitrophenol nitrated mixed (m,p) cresols and
mixtures thereof.
24. The process of claim 19 wherein said substituted nitrobenzene
is in the range from about 500 ppm to 5000 ppm by volume.
25. The process of claim 19 including the addition of a nonionic
emulsifying agent to said aqueous medium.
26. The process of claim 19 including the addition of a
solubilizing agent to said aqueous medium.
Description
FIELD OF THE INVENTION
This invention relates to an improved process for the recovery of
hydrocarbons from hydrocarbon-bearing formations. The process of
this invention is particularly useful for increasing the recovery
of low-gravity crude oils, oil from tar sands, and residual crudes
in hydrocarbon-bearing formations, and is especially useful for
recovery of residual hydrocarbons from formations from which
varying amounts of the more mobile fractions of the original
hydrocarbons in place have been recovered.
DESCRIPTION OF THE PRIOR ART
Among the most important problems related to the recovery of crude
oils from porous matrices are the recovery of low-gravity crudes
(less than 25.degree. API), oils from tar sands, and the secondary
recovery of crude oils containing high percentages of asphaltene
and aromatic components. Some of the techniques that have been
applied to these problems are water flooding, solvent flooding, and
steaming. However, these techniques usually recover only a minor
portion of the petroleum products present in the formation, and may
leave up to 70 to 80 percent of the original hydrocarbons in
place.
Of the improved recovery methods which permit additional recovery
of hydrocarbons from partially depleted formations, water flooding
is one of the more widely practiced processes. Although a
successful water flood may result in recovery of 30 to 50 percent
of the original hydrocarbons left in place, generally, the
application of water flooding to heavy crudes results in much lower
recoveries.
Newer developments in recovery methods for heavy crudes have
included the use of steam injection, applied in several
modifications, including the "push-pull" technique and through-put
methods. Steam flooding processes have resulted in significant
recoveries in some areas of heavy crude reservoirs. Improved
recovery is believed to be at least in part due to the drastic
viscosity reduction which is characteristic of heavy crudes that
accompanies an increase in temperature whereby the mobility of the
crude is improved.
However, the application of these recovery techniques to depleted
formations may leave major quantities of crude unrecovered,
particularly where the crude is tightly bound to the sand particles
of the formation, that is, the absorptive capacity of the sand for
the crude is great. Consequently, process modifications have been
developed that incorporate additives to improve the efficiency of
these processes such as the use of surface-active agents and
miscible liquids that decrease the interfacial tension between the
water and the reservoir crude.
In addition, additives to improve the wettability characteristics
of the formation, may be used. For example, a dilute alkaline
aqueous solution with or without surfactants is known to increase
the wetting characteristics of sand surfaces, and promote a
leaching action and emulsification of the tarry materials resulting
in improved recovery.
However, the increase in recovery resulting from the application of
these additive recovery processes to subterranean formations,
particularly those containing low-gravity crudes, may be only
minimal because of the nature of the crude and the strong
association between its components and the surfaces of the sand
formation.
SUMMARY
This invention comprises displacing the hydrocarbons in a
subterranean hydrocarbon-bearing formation or the oil in tar sands
with an aqueous medium containing a base and a substituted
nitrobenzene.
DESCRIPTION OF THE PREFERRED EMBODIMENT
More specifically, it has been found that when an aqueous medium
containing a base, e.g. an alkali metal hydroxide, and a
substituted nitrobenzene, such as o-nitroanisole, is contacted with
a hydrocarbon-bearing formation, of the hydrocarbons from the
matrix occurs together with the formation of an oil-in-water
emulsion, thereby enhancing the recovery of the hydrocarbons. It
has also been found that a nonionic emulsifying agent may be
incorporated in the aqueous medium so as to facilitate the
formation of an oil-in-water emulsion. Furthermore, the use of a
solubilizing agent in aqueous medium may in addition be preferred
to improve the solubility of the substituted nitrobenzene.
Briefly, the method of the invention can be utilized as an improved
water flood wherein the aqueous medium, described above, is
employed as the flooding agent. Alternately, the method of
invention may be utilized by the injection into a subterranean
hydrocarbon-bearing formation via an injection well of a slug of
the heretofore described aqueous medium containing a base and a
substituted nitrobenzene, and thereafter injecting a drive agent,
e.g. H.sub.2 O as water or steam, so as to drive the slug toward a
producing well, from which the hydrocarbon is produced. In yet
another application, the aqueous medium containing the base and
substituted nitrobenzene can be used in an extractive technique in
conjunction with mined tar sands.
It is known that low-gravity crudes usually contain a higher
percentage of asphaltenes than lighter crudes. The structure of
petroleum asphaltics is quite complex. The result of recent work
has indicated that asphaltenes appear to be a network of planar
aromatic condensed rings, short aliphatic chains, and naphthenic
ring structures. These asphaltene components apparently are capable
of forming charge-transfer complexes both with themselves and with
other compounds including nitrated aromatic compounds. It is
believed that through the formation of charge-transfer complexes
between the asphaltene components of the crude and substituted
nitrobenzenes, such as o-nitroanisole, in an aqueous medium in
accordance with this invention, the crude is effectively desorbed
from the formation matrix and emulsified in the basic aqueous
medium whereby its mobility is improved, leading to improved
recovery. The base, e.g. an alkali metal hydroxide, serves not only
to improve the wettability characteristics of the aqueous medium,
but also improves the stability of the resulting oil-in-water
emulsion.
The base is selected from the group consisting of the hydroxides of
sodium, potassium, ammonium and mixtures thereof, and is used in a
concentration in the range of about 0.001N to 1.ON.
The substituted nitrobenzene which may be used for this process
includes the mono-, di-, and trinitro substituted benzene, and
mixtures thereof, wherein the substitution includes single, double,
and triple substitution and the substituents are selected from the
group consisting of methyl, ethyl, methoxy, ethoxy, hydroxy and
combinations thereof. Concentrations of from about 500 ppm to about
5000 ppm are sufficient, but amounts outside this range may be
employed if desired.
Illustrative of the invention, test runs were made in which an
aqueous medium composed of a O.1N aqueous solution of sodium
hydroxide, and containing 500 ppm of the o-nitroanisole (ONA) was
passed through a pack of 50--60 mesh glass beads containing a heavy
crude (11.degree. API) at an oil saturation of approximately 32
percent. Initially, three pore volumes of the displacing medium
were passed through the pack during which time the displaced oil
and effluent displacing medium were collected and the amount of
displaced or extracted oil determined. The flood was then continued
until either no more oil was displaced or until a total of twenty
pore volumes of the displacing medium (including the first three)
had been passed through the pack.
The following table shows that improved oil recovery was obtained
by the method of this invention and that the presence of the
substituted nitrobenzene, o-nitroanisole (ONA), resulted in about
fifteen times more recovery than that obtained using the sodium
hydroxide solution in the absence of a substituted nitrobenzene.
Furthermore, use of a sodium hydroxide aqueous solution containing
either nitrobenzene or anisole did not show improved oil
recovery.
In addition, other substituted nitrobenzenes that demonstrated
improved oil recovery over that obtained using a sodium hydroxide
aqueous solution included o-nitrophenol and nitrated mixed (m,p)
cresols. The latter agent is a mixture of mono-, di- and
trinitrated meta and para cresols.
In runs which were performed wherein a nonionic surfactant was
incorporated into the solution containing sodium hydroxide and
o-nitroanisole, an additional improvement in recovery was
noted.
The results also demonstrate that a solubilizing agent such as
isopropyl alcohol, can be used in combination with the substituted
nitrobenzene such as o-nitrotoluene (ONT) to increase the
solubility of the substituted nitrobenzene and thereby increase oil
recovery.
The tests demonstrated that the preferred location of the
substituent relative to the nitro group is in the ortho position.
##SPC1##
In a preferred embodiment of the method of this invention, an
injection well is drilled into a subterranean hydrocarbon-bearing
formation through which a slug of the aqueous medium containing the
base and the substituted nitrobenzene as described above is
injected into the formation. The slug is then followed by a
subsequently injected aqueous drive agent, e.g. water. The size of
the slug injected may vary within relatively wide limits, and will
depend on a number of conditions, including the thickness of the
formation, its characteristics, and the conditions for the
subsequent injection of the aqueous drive medium. The aqueous drive
agent may be H.sub.2 O in the form of either water or steam, the
temperature of which may range up to 500.degree. F.
In the passage of the aqueous medium through the subterranean
hydrocarbon-bearing formation, hydrocarbons are desorbed from the
formation, forming an oil-in-water emulsion which is then produced
at production wells. Separation of the hydrocarbons from the
emulsion is accomplished by one of several known emulsion breaking
techniques.
Another embodiment of the method of this invention is illustrated
in its application to the recovery of hydrocarbon materials from
tar sands utilizing the aqueous medium in an extractive technique
in combination with well-known techniques for the mining of the tar
sand, and well-known techniques for the recover of the oil from the
tar sand following its extraction.
In another modification of the process of this invention, an
emulsifying agent capable of forming an emulsion and increasing the
contact area may be incorporated in the aqueous medium. The ideal
surface-active substance is one which acts to produce a relatively
stable, homogeneous dispersion. An example of such a material is a
water-miscible, nonionic surfactant of the hydroxyethylated,
alkyl-aryl phenol category marketed by numerous manufacturers under
such trade names as "Surfonic-N," "Triton-X," "Retzanol-NP," etc. A
preferred particular surfactant of this category is "Surfonic
N-95."
It will be apparent from the foregoing description that the process
is subject to other modifications without departing from the scope
of the invention as defined in the following claims.
* * * * *