Ti
395759532
TO
March 3, 1959
J w. MARTIN ETAL
GASEOUS HYéROCARBON AND CARBON DIOXIDE '
2,875,832
SOLUTIONS IN HYDROCARBONS
Filed Oct. .25, 1952'
6 Sheets-Sheet 1
450
- ETHANE
ICOZ' ETHANE MIXTUR
L50;a RAT
- CARBON DIOXiDE
iCOZ-METHANEMIXTURE L54
V- METHAN
RATIO
u8
S'(OvL0U_BI.oAsT/Yv)|_
mg
m8
I00
50
,“SM
600
_
1200
90o
PRESSURE
I500
_
woo
INVENTORS
PSI
JAMES W. MARTIN
FREDERICK A. HESSEL
FIG. 1
IRVINGVP. HAMMER
JOHN a; RUST
‘Y
MWATTORNEY
-
March 3, 1959.
J. W. MARTIN ETAL
GASEOUS HYDROCARBON AND CARBON DIOXIDE
2,875,832 I
SOLUTIONS IN hYDROCARBONS I
Filed Oct. 23, 1952
6 Sheets-Sheet 2
10 0
990
00
70
'600
so(mncwPmM0REuTxSa.HoFNACz'):OY
JAMES W. MARTlN
2FIG.
FREDERlCK A. HESSEL.v .
‘RVING 9.. HAMMER
JOHN B. RUST
M54
'
ATTORNEY
March 3, 1959
J W. MARTIN ETAL
GASEOUS HYbRocARBoN AND CARBON DIOXIDE
2,875,832
SOLUTIONS IN HYDROGARBONS
Filed Oct. 25, 1952
6 Sheets-Sheet ,3
SOLUBILITY OF ETHANE IN PRESENCE 0F C
OIL
I - COZ- ETHANE MIXTURE - LSOppRATlO
II -
ETHANE
Nb 0
o(v/GsVn01AO.uSsLn)_.v
166
120
180
'40
I00
'
200
300
400
s00
INVENTORS -.
JAMES W. MAR‘HN
FREDERICK A.HESSEL
lRVING 9. HAMMER
JOHN P. RUST
PRESSURE P S!
FIG.3.
BY
SJW'
ATTORNEY
March 3, 1959
J. w. MARTIN ETA!
GASEOUS HYDROCARBON AND CARBON DIOXIDE
SOLUTIONS IN hYDROCARBONS
Filed Oct. 23, 1952
2,875,832 '
6 Sheets-Sheet 5
I00
RCENTAGE INCREASE ‘IN METHANE AND ETHANE
OLUBILI'HES \N PRESENCE OF CO2
90
I — cor ETHANE MIXTURE - 1.50 "RATIO
:1 — coa-mammz wx'ruRE - |.s4,,.RAT|o
- COZ-METHANE mxTuRs - I.30".RATIO
70
SORILNPUEBC‘ATYG
50
2
300
PRESSURE
40o
500
700
‘O0 'NVENTORS
JAMES w. MARTIN
FREDERlCK A.HESSEL
mvmc P. HAMMER
JOHN P. RUST
PSI
FIG. 5
BY
ATTORNEY‘
March 3, 1959
J. W. MARTIN ETAL
GASEOUS HYDROCARBON AND CARBON DIOXIDE
SOLUTIONS IN HYDROCARBONS
Filed Oct. 23. 1952
6- Sheets-Sheet 6
l
WATER,ETC.
/l3
/
2
SEPARATOR
PUMP
4
:G- .._._..____
COMPRESSOR
I
'
" a(
\\
warm»?
OUTPUT
WELL.
INVENTO'RS
JAMES W. MART 1N
FREDERICK A.HESSELL
IRVlNG P. HAMMER
JGHN B. RUST
w'uQa
ATTORNEY
‘g, raised States lfiatent G
1
-
‘
1C@
2,875,332
Patented Mar. 3, 1959
2
2,575,832
GASEQUS HYDRGCARBON AND CARBON DIOX
HDE SSLUTIONS 1N HYDRGCARBONS
Blames W. Martin, Tucltahoe, N. Y., and Frederick A.
Hessel, Upper Montclair, lrving 2‘. Hammer, Nutley,
and John B. Rust, Verona, N. 3., assignors to Oil Re
cover-y Corporation, New York, N. Y., a corporation
of New York
Application October 23, 1952, Serial No. 316,492
2 Claims. (Cl. 166-9)
This invention relates to the recovery of oil or other
hydrocarbon materials from subterranean hydrocarbon
formations, to methods of effecting such recoveries, to
materials and compositions useful in such methods, and
without departing from the scope and spirit of the present
invention.
In connection with that more detailed description there
is shown in the accompanying drawings, in
Figure 1, curves showing solubility of certain gases
in crude oil; in
Figure 2, curves showing crude oil solubility of meth
ane in the presence of carbon dioxide; in
Figure 3, curves showing crude oil solubility of ethane
in presence of carbon dioxide; in
Figure 4, curves showing crude oil solubility of carbon
dioxide in presence of methane and ethane; in
Figure 5, curves showing percentage increase in crude
oil solubilities of certain gases in the presence of carbon
15 dioxide; and in
to products recovered.
It has long been known that the recovery of oil or re
Figure 6, a vertical section through a system utilizing
lated hydrocarbons from subterranean strata or forma
the present invention in oil recovery.
tions is quite ine?icient from the standpoint of the oils or
In accordance with the present invention, it has been
similar hydrocarbons which are left in the strata or
unexpectedly found that the solubility at elevated pres
formations. As a result many methods have been sug 20 sures of gaseous hydrocarbons in crude oil is very ma
gested for recovering such residual oil or hydrocarbons
from the subterranean horizons. Such methods include
procedures for driving out residual oil or hydrocarbons
and various ?uids have been proposed and utilized in
such drive. Gaseous drives empoying air, nitrogen, nat
ural gas or methane, etc., have been proposed and to
some extent utilized.
Liquids, principally water, have been used in water
flooding in efforts to drive out residual oil from the strata
but such liquid or water drives have not been more suc
cessful than the gaseous drive in that they account for
recoveries of the residual oil in the formation of not
more than about the same amounts as those recovered
terially etiected by carbon dioxide, that the e?ect in‘
general is to increase very substantially the solubility
of such lower para?inic hydrocarbons in the crude oil,
and that accordingly, the invention may very advantage
ously be utilized in the recovery of crude oil or related
hydrocarbons from the earth.
The hydrocarbon gases generally include those hydro
carbons both saturated and unsaturated having up to and
including four carbon atoms, among which may be men»
etioned particularly methane, ethane, propanes, butanes,
ethylene, propylene, and acetylene; and also mixtures of
these gases such as natural gas which is predominantly
methane but includes ethane and in some instances,
by the gas drives. The ?uids both gaseous and liquid
have generally been utilized at relatively low pressures.
While high pressures have sometimes been proposed,
higher components as Well as other mixtures such as
they have generally not been utilized in practice and
in covers such individually named gases as well as mix—
those produced synthetically. The term “gas predom
inantly methane" or any analogous term when used here
tures in which a named gas is the predominant, usually
such higher pressures with the stated drives do not appear
.
to warrant such higher pressures since the recoveries’ with 40 major, component.
A particularly valuable gas for use in the present in
the stated drives are not materially higher to justify the
use of the higher pressures. At best therefore even with
vention is the gas obtained in treating subterranean hy
drocarbon bearing formations with carbon dioxide under
the gas drives and water flooding operations some 30%
more or less of the original oil or other hydrocarbons in
, pressure of at least about 300 p. s. i. with more desirably
of from about 600 p. s. i. up to 1400 p. s. i. and higher,
the subterranean strata or formations remains therein
45
there being no upper limit on the stated pressure other
and no methods have been devised in the prior art which
are feasible commercially for obtaining greater recoveries.
than convenience or economy. It has been found that
the e?luent from such processes contains carbon dioxide
in addition, in prior art recovery methods, gas release
and hydrocarbons which are both gaseous and liquid
from the crude during production, exhibits deleterious
under standard conditions of temperature (0° C.) and
effects such as increase in viscosity, surface tension, and
speci?c gravity, as well as shrinkage. No simple satis4
pressure (760 mm.) and after liquids are condensed from
such et'lluent the residuum may desirably be recycled to
factory methods of preventing or control of such gas
be used as the gaseous medium for contacting hydrocar
release has heretofore been possible.
Among the objects of the present invention is to im
bon oils in situ in the earth or otherwise. Such gas re
prove methods of recovery of oil or other hydrocarbons 55 siduum contains substantial amounts of normally gaseous
from subterranean hydrocarbon formations.
hydrocarbons and some higher hydrocarbons also. Its
Other objects include methods of control or regulation
of gas release from oil or other subterranean hydrocar
the locality where, it is produced. The quantity of meth
bons during recovery.
ane in the gases may be greatly reduced from normal for
-
character may depend on the conditions under which, and
Further objects include methods for increasing the 69 such locality, and ethylene and propylene may be sub
stantially absent. But substantial quantities of higher
solubility of gaseous hydrocarbons in crude oil or related
hydrocarbons.
unsaturates (materials soluble in sulfuric acid) may be
present which may run from 1 to 20% by weight, for
Still further objects include compositions useful in car
example up to 7.5% of hydrocarbons in the range from
rying out such methods.
Still further objects include products obtained in oper 65 butyleno to pcntylene. Under other conditions, substan
ations as set forth above.
Stillfurther objects and advantages of the present in
tial amounts of methane may be present. .
Thus the e?luent produced may be utilized as a source
of gas to be employed in accordance with the present
vention will appear from the more detailed description
invention to produce solutions of relatively high content
set forth below, it being understood that such more de
tailed description is given by way of illustration and ex 70 of dissolved gaseous hydrocarbons. The ellluent re
siduum referred to above may be directly recycled to the
planation only, and not by way of limitation, since various
in situ subterranean hydrocarbons if desired, or may be
changes therein may be made by those skilled in the art,
cameos
s
forti?ed by addition‘ oicarbon dioxide or any of- the -'
oxide to methane of from about 2:1 or‘
gaseous hydrocarbons saturated or unsaturated or both,
With ethane, pressures may be from about 50 to 500~ "
p. s. i. partial pressure of ethane and ratios of partial
pressures of carbon dioxide to ethane of from about
before being recycled. In any event, this residuum will
be used within the pressure ranges speci?ed herein. Some
representative examples of the hydrocarbon content of
such masons residua are: (a) a product containing un
sanirates constituting about 9.4% of the total hydrocar
tolllzl.
1.5:1 to 0.l:1;‘ preferred pressures being from about
150 to 400 p. s. i. and partial pressure ratios of from
about 1.5:! to 1:1. For mixtures of_ the gaseous hy
bons present, there being about 14.5% of total hydro
drocarbons, the pressure values will usually lie between
carbons in the form of hydrocarbons of at least {our
those for the individual gases and depend on the pre
carbon atoms; and (b) unsaturates of about 4.5% of the 10 dominant component; but here again there are critical
total hydrocarbons present, with about 6.3% of the hy
values where the relation departs materially from a
drocarbons present having at least four carbon atoms.
straight line function.
The liquid petroleum hydrocarbon fractions include
both crude and re?ned petroleum oils and fractions ‘
thereof. They may be para?’inic base ‘lype oils, naph
th?ic base type oils, etc, and the fractions thereof.
The invention will be au?iciently illustrated below by use
or‘ a ?ennsyivania grade crude oil as represented by
crude oil.
'
_
-
r
In producing'the solutions any manner of'contacting
the material may be used. The oils or other liquid by
drocarbons may be contaclcd'with the gases until the
desired solution is obtained. ‘Mixtures of carbon di
oxide with the desired lower para?inic hydrocarbons
may be used to contact the oil to produce the solution;
or, the gases may be successively contacted with the oil
,
While it has been found that the normally gaseous 20 to produce thc'solutions. -.In_the examples given below,
when the combination of Cog/methane was used, the oil
hybons referred to above both, alone and in ad
mixture, are substantially more soluble in liquid pe
was ?rst saturated withv carbon dioxide, followed by
contact with methane. This procedure was desirably
troleum hydrocarbon fractions such as crude oil, the e?ect
or‘ the hydrocarbon gas on the solubility of the carbon 25 reversed when ethane was used since the maximum pres~
dioxide in the liquid petroleum hydrocarbon fractions is
sure of gaseous ethane at 70° F. amounts to only 528
not always the same. Thus, gases predominantly
p. s. i. The ethane-carbon dioxide examples referred
to below were produced in this way. The actual pro
methane such as methane per se and natural gas, de
cedure may vary depending on the particular gases, the
crease the solubility of carbon dioxide in for example
crude oil, while the hyn gases above methane 30 type of crude oil, temperature, total pressures, partial
generally increase the solubility of carbon dioxide in the
pressures of the components of the gaseous mixtures, etc.
crude oil for example. Thus methane and gases pre
The resulting solutions may vary in character depending
dominantly methane, therefore differentiate themselves
on the components and the conditions under which they
in certain characteristics from gases of at least two,
are produced and maintained. These solutions may be
carbon atoms, and are not equivalents in all respects.
'
35
Generally as to all of the gaseous_ hydrocarbons re
ferred to herein, it may be said that in the presence of '
used as a source of the oils or of the gaseous components
thereof and'may be shipped in pressure containers to
points of utility.
carbon dioxide under superatmospheric pressure, increased
Although an appreciable amount of data is available
solubility of the hydrocarbon gas in the liquid hydro~
in the literature dealing with the solubility of natural
carbon fraction is exhibited. However, the solubility is
gas, methane, and other gases in various crude oils or
in?uenced materially by a number of factors, including 40 other hydrocarbon sytcms, at elevated pressures, very lit
the partial pressure of the gaseous hydrocarbon in con
tle information is available concerning the similar solu
tact with the liquid hydrocarbons and the ratio of the
bility of carbon dioxide, ethane, or mixtures of carbon
dioxide and gaseous hydrocarbons.
partial pressure of the carbon dioxide to that of the
gaseous hydrocarbon present. These factors are very
For utilization compartively herein, the solubility of
important in the present invention, and critical values 45 carbon dioxide, methane and ethane in Pennsylvania
will be evidenced where the order of increased solubility
grade crude oil at 27° C. was determined.
_ I
is substantial. For a given order of increased solubility,
In these determinations, substantially the same pro
as the- rau'o of partial pressures of carbon dioxide to . cedure was followed in all instances. A given volume
of crude oil was contacted intimately with the gas or
gases for the desired determination, until saturation was
hydrocarbon gas increasm, the lower is the partial pres
sure of the hydrocarbon gas which is needed to give
a particular order of increased solubility. The solubility
in general, is not a straight line relation however, and .
criiicai points or areas are evidenced in which the increase
in solubility is very substantially evidenced as will ap
rcached, which usually required several hours. When the
a pressure remained constant, this was taken as indicating
that maximum solubility of the gas in the oil had been
reached. The gas dissolved in the oil was determined.
pear from data given below. Here again methane de- ‘ ‘ Standard methods were used throughout.
viates in its action as compared with the other hydro- .
The data for the stated gases is given below in Table I
carbon gases, since at lower partial pressure ratios of
and plotted in Figure 1 of the drawings.
‘
carbon dioxide to methane or gases predominantly
methane, the partial, pressure of methane to give sub
TABLE I
stantially increased solubility may have to be very ‘ma 60
Solubility of gases in Pennsylvania grade crude oil
tcrinlly greater than for'exaniple is the case with ethane.
A. P. l.‘ gravity 42'
As a general rule, the carbon dioxide will he at least
50% by volume of the total gas in contact with the
[Temperature 27° 0.]
liquid hydrocarbons, so that the ratios of partial pressure
of carbon dioxide to hydrocarbon gas will be at least
1:1. it may be as low as 0.1:1 but in such cases, the
partial pressure of the hydrocarbon gas present will have
to be very much greater as for example with methane
or the order of 1400 to 16% p. s. i. in order to get sub
stantial increase in solubility over that obtained in the
abs-once of carbon dioxide. The
prwnrc ratio
will generally not emed about 2:1 and usually not above
15:1.’ -'l‘hus
methane, the pressure may generally
be a partial pressure of methane of horn about 50 to
the p. s. i. and a ratio of partial prmsurce of ‘35303 di- 15
‘Solubility 01 gas (vols. gulvol. oll)
Pressure, p. s. 1.
Carbon Methane Ethane
Dioxide
1D. 0
so. 4
2!. 8
40. 6
51. 4
4. 4
8. 0
ll. 5
14. 6
18. 1
64. 7
87. 8
129.0
194. 2
2i. 0
47. d
86. 2
1M. 8
332
2!. 8 ....... -.
23. 4 ........ .
'
27.0 ....... ..
N.
..........
2,875,852
5
6
The following points may be noted in this connection.
The solubility of methane is practically a straight line
function over the pressure range examined. The car
bon dioxide data are interesting in that while the solu;
bility increases gradually over the range of 100 to 500 5
p. s. i. in‘a straight line fashion, a rather sharp increase
in the slope of the solubility curve occurs at the 600-700
3:. s. i. pressure point. Above this inflection point the
solubility of carbon dioxide increases rapidly with in
creasing pressure. ’Ihe solubility of ethane increases
Solubility of gases in Pennsylvania grade crude oil
A. P. I. gravity 42'
[Temperature 27° 0.]
Total Pressure,
p. a. l.
rapidly with increasing pressure with the result that at a
pressure of 500 p. s; i. the solubility is as much as 232
volumes of ethane per volume of crude oil.
Wort: was carried out on mixtures of carbon dioxide
and methane. The crude oil was contacted with gaseous
mixtures given in the speci?c examples of Table II under
the conditions set forth there. The data is given below
in Table i! and plotted in Figures 2 and 4 of the draw
lugs.
'
'
_
gaseous mixtures in examples tabulated in Table Ill be
low, and plotted in Figures 3 and 4 of the drawings.
TABLE III
CO’,
Ratio,
Total
p. p.
p. a. i.
01H‘,
p. p.,
00,"!
can»
gas
solu-
119
242
36‘!
475
637
81
168
236
325
353
1. 47
1. 63
1. 54
1. 46
1. 48
blllty
O01
oolublllty
- CzHs
solu
btltty
(V01. who] oil)
27. 0
68. 5
109. l.
193. 2
443. 6
ll. 7
E. 9
44. 2
B3. 1
266. 0
15. 3
87. ll
64.0
110. 1
187. 6
These data are particularly interesting in that not only
20 does the presence of carbon dioxide increase the solu
bility of ethane in oil at a given pressure but, at the
same
time, the presence of ethane increases the solubility
Solubility of gases in Pennsylvania grade crude oil
of the carbon dioxide. These examples were carried out
A. P. l'. gravity 42°
at a C0,:QH, partial pressure ratio of 1.50:0.04. At
[Temperature 27° 0.]
25 this ratio, an examination of Figures 3 and 4 shows that
a very rapid increase in solubility occurs in both the car
CO3,
Ratio, Total C O:
CH‘
bon dioxide and ethane curves at partial pressures of:
Total ;.
, p. p.
0H4,
COND/
solusolu
about 450 and 325 p. s. i. respectively.
p. e. s.
p. a. l. p. p.,
on.”
solu- blllty blllty
blllty
On the basis or‘ the data obtained it is apparent that
TABLE II
i2!
244
355
492
592
‘H2
837
9%
78
156
246
318
408
@188
663
610
.
1. 56
l. 66
l. 45
1- 50
1. 45
1. 46
l. 49
l. 82
(Vol. gas/vol oil)
13. 15
9. 8
3.
28. 1
an. 7
7.
37. 4
27. 3
10.
90. 8
46. 2
14.
77. 9
69. 2
3.8.
93. 5
68. 3
25.
116. 1
83. d
82.
133. 0
97. 4
35.
30 the presence of carbon dioxide has a marked effect in
increasing the solubility of gaseous hydrocarbons in
crude oil. In view of the data obtained with both
methane and ethane it appears that the greater the mo
lecular weight of the hydrocarbon involved, the more
as marked is the increase in solubility brought about by the
presence or‘ carbon dioxide.
Since natural gas consists mainly of methane with
varying quantities of ethane and higher hydrocarbons,
it was noted that solubility of methane in crude oil
it can be expected that the increase in solubility of
in the presence of ‘carbon dioxide is related to the equi 40 natural gas in the presence of CC: will be somewhere
ratio of the partial pressures of the two gases.
between that of methane and of ethane. Solutions of
in general, the greater the CO3:Cl-L partial pressure
natural gas and carbon dioxide in crude oil were pro
ratio, the greater the increase in the methane solubility
duced. A synthetic natural gas consisting of 80%
at a given pressure. Thus, in the data given in Table
methane and 20% ethane was used with Monder crude
II the CO=:CH4 partial pressure ratios at the equilibrium
oil to illustrate this phase of the invention.
?nal pressure was maintained between the limits of
l.54:0.08.- However, for comparison purposes there is
also included in Figure 2 the curve obtained when the
CO3:CH4 partial pressure ratios were kept within the
limits of 1.30:0.08. It can be seen'that the presence
oi larger amounts of CO3 in the equilibrium gas mixture
consistently increases the solubility of the methane at
a given pressure. It is to be noted that at the C?gzCl-Lx
ratios of either 1.54 or 1.30 the methane solubility
curve shown a pronounced change of slope at a partial 55
At a CO=zsynthetic natural gas ratio of 1.30 and a
natural gas partial pressure of 540 p. s. i. the increase in
natural gas solubility as compared to the increase in
solubility of CH4 under the same conditions were as
follows:
~
Solubility in
P
Goa Mixture
V rrobably related to the fact that at 400 p, s. i. CH4
partial pressure and a (30120-14 ratio of 1.54, the partial
‘pressure of the carbon dioxide present is slightly above
l’eroent tn
amaze in
011 (Vols 0!
solubility
hydrcmroon
over that ol
gas/vol or
pressure of about 400 p. s. i._and 450 p. s. i. respec- _
tively in contrast to the solubility curve for methane
along which no distinct increase in slope Occurs over
the pressure range studied. This change of slope is
lvanta
Grnde Crude
pure 0
01!)
CH ................................... __
19. 5
............ .
001: CH; ............................. -_
28. 0
33. 3
COnNatural G8‘! (m 0114, m 03H».
35
80.0
it is signi?cant that while the partial pressure of the
ethane in the natural gas mixture at 540 p. s. i. is only
slightly more than 100 p. s. i., the percentage increase in
rnal cazbon dioxide solubility curve also begins to show
solubility
of the total gaseous hydrocarbon mixture was
a sharp increase in slope.
05
more than double that of methane from a carbon dioxide
With regard to the effect of the presence of methane
methane mixture (1.30 C‘OgiCHQ ratio).
on the solubility of carbon dioxide, it can be seen by
With respect to the actual percentage increase in solu
' examining Fig. 4, that the resulting solubility curve is
bility of methane in the presence of CO, over that of
practically linear in nature. There is no longer a sudden
change in slope at the 600 p. s. i. pressure point and 70 pure methane, reference to Fig. 5 of the drawing shows
that to attain the same 30% increase in solubility, the
the net result appears to be a marked reduction in the
partial pressure of the CE; in a GUI-CH4 mixture of a
carbon dioxide solubility particularly in the pressure
1.5 C0,:CH4, p. p. ratio need only be 420 p. s. i. as com—
range o! 600-1600 p. a. i.
pared to 530 p. s. i. CH4 when the gas mixture has a
The production of solutions of ethane and carbon di
oxide was carried out by contacting the crude oil with 75 1.3 C0,:Cl-L p. p. ratio. Furthermore, when the ratio
i300 p. s. i., which is the pressure area wherein the nor
53575632
?
_ _
is 1.3 C0,:Ciir no‘particular increase in methane solu
When recycled, the gases may be forti?ed by addition
bility occurs until the methane partial pressure is above
of the necessary added components to reconstitute the
?uid to be introduced into the formation.‘ Where a
water or other drive is used in the process of treating
266 p. s. i. I Should the C0,:CH4 ratio be reduced fur
ther, both the total pressure of the gas mixture and the
methane partial pressure would have to be higher before
the increase in methane solubility would becomev ap
parent.
_
The invention has particular utility in the field of
the subterranean strata, water or other medium may
be introduced through valved line 12 to pump 13, and
then led by line 14 into the input well 5.
Liquids separated as above may be shipped to re?n
oil recovery by utilization of carbon dioxide to increase
eries or otherwise treated.
Or the solution of carbon
Since it is generally true that formation volume factors
oil, may be collected in containers under the necessary
pressure and sent to storage or to re?neries, or used as
the solubility of gaseous hydrocarbons in crude oil. 10 dioxide and lower aliphatic hydrocarbons in the crude
of oils increase linearly with the volumes of gas dis
solved, it is interesting to note the total gas solubility in
Pennsylvania grade crude oil of the carbon dioxide
gaseous hydrocarbon mixtures under investigation (Fig.
2). it can be seen that at a pressure of 900 p. s. i. the
a source of the contained gases or oils.
,
Having thus set forth our invention, we claim:
1. In a method of recovering liquid hydrocarbons
from a subterranean oil formation, the steps of inject
ing into such formation carbon dioxide and a gas, pre
dominantly hydrocarbon of from 2 to 4 carbon atoms,
solubility of methane in the crude is only 30 volumes
per volume of oil while a COT-CH, mixture at a par
the partial pressure of the gas, predominantly hydro
tial pressure ratio of 1.5 more than doubles the total
gas solubility, 4 g., 70 vols. gas/vol. oil; The total 20 carbon, being within the range from about 150 to about
500 p. s. i., the ratio or’ partial pressure of carbon di
solubility of a carbon dioxide-ethane mixture at ap
oxide to gas, predominantly hydrocarbon, being in the
proximately the same partial pressure ratio approaches
range. from about 2:1 to about 1:1, contacting said
the exceedingly high value of 440 vols. gas/vol. oil.
liquid hydrocarbons with said gases at a temperature
Thus, in primary recovery, carbon dioxide or mixtures
of carbon dioxide and gaseous hydrocarbons, particu 25 of the order of 27 degrees C., and withdrawing from
said formation an ei?uent comprising liquid hydrocar
larly lower gaseous hydrocarbons may be introduced
into the formation to control or prevent or regulate gas
release from the crude in the ground, due to increase
in total gas solubility brought about by the presence of
carbon dioxide. Ill effects of gas release from the crude
during production, such as increase in viscosity, surface
tension, and speci?c gravity, as well as shrinkage, may
thus be counteracted. ‘The desired gases may be intro
duced directly into the formation for this purpose.
Where the formation contains the necessary lower
para?inic hydrocarbon, only carbon dioxide need be
introduced.
Where necessary, a carbon dioxide and
lower paraf?nic hydrocarbon may be introduced either
bons and said gases.
2. In a method of recovering liquid hydrocarbons
from a subterranean oil formation, the steps oi inject
ing into such formation carbon dioxide at a total pres
sure of at least about 300 p. s. i. to form an e?uent con
taining carbon dioxide and hydrocarbons which are
gases and liquids at standard conditions of temperature
and pressure, condensing liquid hydrocarbons from said
etiluent, recycling the residual e?luent including car
bon dioxide and hydrocarbons containing predomi
nantly 2 to 4 carbon atom hydrocarbons in substantial
amount into an oil formation, contacting liquid hydro
carbons therein at a temperature of the order of 27
as a__mixture or successively. The pressures of the gases
both total and partial may be as indicated above in the 40 degrees C. with said recycled residual ethuent, the par
tial pressure of the 2 to 4 carbon atom hydrocarbons
examples there given. ‘
in the recycled gas being within the range from about
As exemplary of a. system that may be used in this
300 to 500 p. s. i. and the ratio of partial pressure of
way reference may be made to Figure 6 of the drawings
which is a diagrammatic rcpresentation‘for recovery _ carbon dioxide to 2 to 4 carbon atom hydrocarbons be
ing ‘from 2:1 to 0.1:1, and withdrawing from this for
of oil utilizing an input well into which the gases are
matron an e?iuent, comprising liquid hydrocarbons and
introduced and passeddnto the strata. As there shown,
said gases.
the gaseous mixture of ?uid composition entering from
any desired source through inlet pipe 1 passes through _
compressor 2 if desired, where the pressure may be
raised to the order of pressures set forth above for use,
and then passes through pipe 3 by way of head 4 into
the input well 5 from which the ?uid under the desired
Hnsrciaanmsuetuapmsz
UNITED STATES PATENTS
‘ 1,249,232
~1,826,3‘71
2,166,160
through head 7 and valved pipe 8 into ~separator 9 55 2,188,013
2,623,596
where if desired separation may be made between
pressure enters the subterranean oil strata or formation
S. The effluent enters outlet well 6 and is removed
iquids and gases, liquids being‘ withdrawn through
valved outlet 1% and gases removed at valved outlet ll.
,
.
“ Squires _____________ .... Dec. 4, 1917
Spindler ____________ ..- Oct. 6,
King ______________ -- July 18,
Pilat et al. __________ .._ Jan. 23,
_Whorton et a1... ..... __ Dec. 30,
GI'HER REFERENCES
I
1931
1939
1940
1952
_
'
Petroleum Development 8: Technology in 1925, P:
Such gases may beiused for recovery of constituents 60 troleum Diva, A. I. M. E. pp. 51-63.
therefrom and the residues recycled, or the entire gas
_ increasing the Recovery of Petroleum, Osgood, vol.
eons product without separation may be recycled.
1, (c) 1936, page 113.
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