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Патент USA US3087550

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United States Patent 0 ’ 1C6
3,087,540
Patented Apr. 30, 1963
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3,087,540
Harry W. Parker, Bartlesville, Okla, assignor to Phillips
aqueous solution of a suitable iron compound into a se
lected section of a permeable carbonaceous stratum under
IN SITU COMBUSTKON USING IRON CATALYSTS
Petroleum Company, a corporation of Delaware
No Drawing. Filed July 20, 1959, Ser. No. 828,027
17 Claims. (Cl. 166--11)
non-precipitating conditions so as to impregnate the pores
of the stratum with said compound; thereafter driving
excess liquid out of the selected section by injecting into
same a suitable flushing gas so as to leave adsorbed iron
compound in the pores of the stratum; thereafter igniting
This invention relates to a process for the catalytic in
situ combustion of carbonaceous strata. A speci?c as~
the section of stratum and moving a combustion front
therethru so as to produce hydrocarbons therefrom; and
pect of the invention pertains to a process for depositing 10 recovering the produced hydrocarbons. In this manner
an iron-containing catalyst in carbonaceous strata.
the iron compound deposit in the pores of the stratum
In situ combustion in the recovery of hydrocarbons
lowers the temperature of combustion and the combus
from underground strata containing carbonaceous ma
tion front is moved thru the stratum at a faster rate than
terial is becoming more prevalent in the petroleum indus
is possible in the absence of the iron compound.
try. In this technique of production, combustion is ini 15
Another broad aspect of the invention, applicable to
tiated in the carbonaceous stratum and the resulting com
strata containing connate Water having dissolved therein
bustion zone is caused to move thru the stratum by either
one or more salts which cause precipitation of the in
inverse or direct air drive whereby the heat of combus
jected iron compound and plugging before it reaches all
tion of a substantial proportion of the hydrocarbon in
of the pores of the stratum to be impregnated, comprises
the stratum drives out and usually upgrades a substantial 20 displacing the water in the stratum by injecting the solu
"as-
proportion of the unburned hydrocarbon material.
‘The ignition of carbonaceous material in a stratum
around a borehole therein followed by injection of air
thru the ignition borehole and recovery of product hy
tion of iron-containing compound having added thereto a
suitable sequestering or chelating agent which prevents
precipitation of the iron compound; and after the iron
compound is adsorbed in the pores of the stratum, dis
drocarbons and combustion gas thru another borehole in 25 placing the excess liquid with air or other suitable dry
the stratum is a direct air drive process for effecting in
ing gas to prepare the impregnated stratum for in situ
situ combustion and recovery of hydrocarbons from the
combustion catalyzed by the iron-containing catalyst. It
stratum. In this type of operation the stratum usually
is also feasible to ?rst drive the water out of the section
plugs in front of the combustion zone because a heavy
of stratum to be impregnated with the catalyst and pro
viscous liquid bank of hydrocarbon collects in the stratum
duced by in situ combustion, by injecting thereinto a
in advance of the combustion zone which prevents move
ment of air to the combustion process. To overcome
this difficulty and to permit the continued progress of the
suitable ?ushing ?uid such as clear water or inert gas and
then injecting the iron-containing solution also containing
the sequestering or chelating agent.
combustion zone thru the stratum, inverse air injection
A suitable sequestering or chelating agent comprises
has been resorted to. By this technique, a combustion 35 citric acid and its salts and polyaminopolycarboxylic
zone is established around an ignition borehole by any
acids and their water soluble salts, particularly, sodium
suitable means and air is fed thru the stratum to the
and potassium, and sodium and potassium polyphos
combustion zone from one or more surrounding bore
phates. The polyaminopolycarboxylic acids and their
holes.
sodium and potassium salts are known in the trade as
In situ combustion techniques are being applied to tar 40 “Versenes.” The potassium and sodium polyphosphates
are known as “Calg-ons.”
sands, shale, Athabasca sand and other strata in virgin
state, to coal veins by fracturing, and to strata partially
The preferred iron salt is ferric nitrate Fe(NO3)3.9H2O
depleted by primary and even secondary and tertiary re
which is readily soluble in water up to more than 10
covery methods.
weight percent calculated as Fe. Other iron compounds
Recovery of hydrocarbons from carbonaceous strata, 45 comprise iron carbonate, iron chloride, iron carbonyl,
and etc. When utilizing ferric nitrate, the impregnating
solution preferably contains from 0.5 to 10 weight per
fractured coal veins, and other permeable carbonaceous
such as various types of oil and tar sands, porous and
deposits is a rather slow process and consumes an appre
cent iron calculated as Fe2O3.
ciable proportion of the carbonaceous material as fuel
during the process. I have found that the in situ combus
tion process can be speeded up and the combustion tem
ing or chelating agent should be comparable or equiva
perature can be decreased so that a smaller proportion of
The amount of sequester
lent to the amount of iron compound in the solution.
The section of stratum to be produced may comprise
the stratum between a central ignition well and a ring of
the carbonaceous deposit is consumed in the process,
surrounding wells, in which case the injection of solution
thereby producing a greater amount of hydrocarbons and
is preferably effected thru the central ignition well with
55
fuel gas from the deposit in a shorter period of time.
water, solution and air being produced thru the wells in
Accordingly, it is an object of the invention to pro
the ring. After drying out, the ignition is initiated
vide an improved process for producing hydrocarbons
around the central well by any suitable means, such as
and other fuel from a carbonaceous stratum by in situ
by burning a fuel pack in the ignition well adjacent the
combustion. Another object is to provide an in situ
stratum and driving a combustion zone into the stratum
combustion process for producing a permeable carbo 60 by direct or inverse drive in conventional manner. The
naceous stratum at a faster rate and with production of a
combustion front is then driven thru the stratum by in
‘greater proportion of the carbonaceous material present
jecting combustion-supporting gas thru the wells in the
in the stratum. A further object is to provide a catalytic
ring (inverse drive). The produced hydrocarbons are
process for recovery of hydrocarbons by in situ combus
recovered thru the central ignition iwell. Catalyst dep
65
tion. It is also an object of the invention to provide a
osition does not increase the rate of propagation or lower
process for depositing an iron-containing catalyst in a
combustion temperature with direct drive but it would
carbonaceous stratum which avoids precipitation of iron
probably allow operation under more di?icult conditions.
compounds on their Way into the stratum so as to avoid
The section of stratum to be ignited and produced by
plugging of the pores of the stratum. Other objects will
in situ combustion may comprise the intervening stratum
become apparent upon consideration of the accompany 70 between a line of- ignition wells and one or two parallel
ing disclosure.
lines of Wells, preferably, two, i.e., one line on each side
A broad aspect of the invention comprises injecting an
of the line of ignition wells. The solution may be injected
3,087,540
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thru the line of ignition wells, which is preferred, or thru
the lines of offset wells until solution appears in the
stratum containing water and penetrated by a pair of
spaced apart wells by in situ combustion comprising pass
line(s) of wells opposite the wells being used as injection
ing a flushing gas thru said stratum between said wells to
wells. After ?ushing out excess liquid, leaving iron com
pound in the pores of the intervening stratum as by air
said stratum between said wells an aqueous solution of
drive out water; thereafter injecting into the section of
an iron compound under non-precipitating conditions;
drive, combustion is then initiated along the line of igni
tion wells, preferably by igniting alternate wells in the
thereafter driving excess solution out of said section be
tween said wells With a suitable ?ushing gas so as to leave
line and injecting air thru the remaining wells so as to
adsorbed iron compound in the pores of said section;
move the combustion front across the intervening strips
of stratum between wells in the line. When the combus 10 continuing the injection of said gas so as to dry out said
stratum intermediate said wells; thereafter igniting said
tion zone is established completely along the line of wells,
section adjacent one of said wells and injecting air into
combustion fronts are then driven by direct or inverse
driyle across the intervening strips to the lines of offset
the ignited section so as to move a combustion front
therethru toward the other of said wells so as to produce
we s.
hydrocarbons therefrom whereby said iron compound
Tests have shown that iron compounds thus deposited
in a ‘carbonaceous stratum reduce the ignition and com
bustion temperatures ‘and also accelerate the ?re propaga
lowers the temperature of combustion and causes move
ment of the combustion front thru said section at a faster
tion rate. By reducing the combustion temperature, sub
rate than in the absence of said compound; and recovering
the produced hydrocarbons from one of said wells.
stantially more oil or other hydrocarbon material may
2. The process of claim 1 wherein said compound is
be produced from a given reservoir because of hundreds 20
ferric nitrate in a concentration in the range of 0.5 to 10
of-thousands or millions of tons of rock in the reservoir
are heated to a lower temperature, thereby requiring less
weight percent (calculated as F6203).
3. The process of claim 1 wherein said solution is
fuel consumption than with a higher temperature. Since
injected into a section of stratum between a central igni
the temperature of combustion is reduced as much as
about 70 to 100° F. by the use of iron catalyst, the saving 25 tion well and a surrounding ring of wells, said igniting is
effected in the area adjacent said ignition well, and the
resulting combustion front is advanced toward the wells
in said ring.
4. The process of claim 1 wherein said solution is
injected thru a line of ignition wells to a parallel line of
wells on each side of said line of ignition wells; and com
bustion fronts are driven from said line of ignition wells
to each parallel line of Wells.
5. A process for producing a permeable carbonaceous
stratum penetrated by a pair of spaced apart wells by in
situ combustion which contains Water having salts dis
the combustion front thru the sand by about 15 percent
solved therein, which comprises ?ushing said water out
and decreased the combustion temperature at least 70° F.
of the section of stratum between said Wells to be pro
Of course, inverse air injection was used.
duced by displacing same with a suitable flushing fluid
In other tests, a tar sand from the Bellamy, Missouri,
area was burned clean of carbonaceous material and 40 injected thru one of said wells and produced thru the
other; thereafter injecting into said section through one of
found to contain 1.7 weight percent iron. A portion of
said wells an aqueous solution of ferric nitrate containing
this clean sand was impregnated with an‘ aqueous solution
a chelating agent which prevents precipitation of Fe com
of ferric nitrate made by dissolving 65 gr. Fe(NO3) 3.9H2O
pounds, to displace said ?ushing agent; after Fe compound
in 100 ml. water. The impregnated sand was dried and
the nitrate decomposed by heating. The effect of the 45 is adsorbed in the pores of said section, displacing excess
solution with air injected thru one of said wells and dry
unimpregnated and impregnated sands on the oxidation
ing out said section; thereafter igniting said section around
of propane in air was determined by packing the sand
in fuel and increase in production of hydrocarbons from
a reservoir represents a substantial economic advantage.
The process of the invention not only produces more oil
but does so in a shorter period of time than without the
use of iron catalyst.
To illustrate the effects of the invention, a tar sand was
produced with and without ‘added iron catalyst to deter
mine the temperature of combustion and the rate of move
ment of the combustion front thru the sand. It was found
that the iron catalyst increased the rate of movement of 35
The sand was
one of said wells and continuing the injection of air so
heated while passing air containing 10.3 volume percent
as to move a combustion front thru same toward the
propane therethru at a ?ow rate of 181 standard cu. ft.
per hour per square foot of cross section of sand. It was
other of said wells; and recovering hydrocarbons pro
duced by the combustion thru one of said wells.
6. The process of claim 5 where the flushing fluid is
water relatively free of precipitating salts.
7. The process of claim 5 wherein the ?ushing ?uid is
samples in a glass tube 2.83 cm. ID.
found that the temperature required to consume 50% of
the oxygen was reduced from 1160 to 980° F. by increas
ing the iron content of the sand from 1.7 to 4.0 weight
percent.
Other tar sands were analyzed for iron content and it
was found that the iron content ranged from .36 to 1.7
55 a gas.
8. The process of claim 5 wherein the ?ushing fluid is
air.
9. The process of claim 5 wherein said chelating agent
(Bellamy sand). Monogas, Venezuela, tar sand had an
is citric acid.
iron content of 0.7 weight percent while that from the
10. The process of claim 5 wherein said chelating
Sulfur, Oklahoma, area had 0.36 weight percent iron. 60
agent is a member of the group polyaminopolycarboxylic
Two sands had an iron content of 1.5 and 1.7 weight per
acids and their water soluble salts.
cent, respectively. It is reasonable to assume that the
11. The process of claim 5 wherein said chelating
improvement in catalytic effect of a given deposit of iron
agent is sodium polyphosphate.
in a sand will be better in sands of low initial iron content.
12. A process for depositing an iron-containing catalyst
During the in‘ situ combustion phase of the process, the
in a section of a permeable carbonaceous stratum between
iron compound is probably decomposed or converted to
a pair of spaced apart wells therein to be produced by in
iron oxide; however, the invention is not predicated upon
situ combustion which section contains water having dis
any theory as to the form in which the iron exists at the
solved salt therein capable of precipitating iron compound
time of its catalytic effect upon the combustion process.
Certain modi?cations of the invention will become ap 70 which comprises ?ushing said water out of said section
of stratum by displacing same with a suitable ?ushing
parent to those skilled in the art and the illustrative de
?uid injected thru one of said wells and produced thru
tails disclosed are not to be construed as imposing un
the other; thereafter injecting thru one of said wells into
necessary limitations on the invention.
said section an aqueous solution of an iron compound
I claim:
containing a chelating agent which prevents precipitation
1. A process for producing a permeable carbonaceous
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3,087,540
of Fe compounds, to displace said ?ushing agent thru
16. The process of claim 12 wherein said chelating
agent is a member of the group polyarnino polycarboxylic
acids and their water soluble salts.
17. The process of claim 12 wherein said chelating
section, thereby depositing Fe compound in said section. 5 agent is a member of the group sodium and potassium
the other well and after Fe compound is adsorbed in the
pores of said section, displacing the excess solution be
tween said wells with a drying gas and drying out said
13. The process of claim 12 wherein said iron com
pound is ferric nitrate.
-14. -The process of claim 13 wherein the concentration
of said ferric nitrate in said solution is in the range of 0.5
to 10 weight percent (calculated as Fe2O‘3).
15. ‘The process of claim 12 wherein said chelating 1”
agent comprises citric acid and said iron compound com
prises ferric nitrate.
polyphosphates.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,382,471
Frey _______________ __ Aug. 14, 1945
2,871,942
Garrison et a1. ________ _.. Feb. 3, 1959
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