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Патент USA US3091235

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May 28, 1963
Filed Dec. 29. 1958
2 Shae
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May 28, 1963
Filed Dec. 29, 1958
mm VA
United States Patent 0
Patented May 28, 1963
In a copending application, Serial No. 741,329, ?led
June 11, 1958, now Patent No. 3,035,638, is a full and
Theodore W. Legatslri, Bartlesville, Okla., assignor to
Phillips Petroleum Company, a corporation of Dela
taining inverse in situ combustion in a subterranean car
complete description of a method for initiating and main
bonaceous material containing formation. In this appli
cation. it is stated that one important point of said on
Filed’ Dec- 29, 1958, Ser. No. 783,447
7 Claims. (Cl. ?ll-156)
pcnding application in solving the problem of maintain
ciently to initiate combustion. Thus, there is overheat
ing, at one point and underheating at another point.
Accordingly, it is an object of this invention to provide
trated by substantially semispherical closures 14 and 14a,
respectively. Disposed within annulus 23 and the lower
ing in situ combustion by inverse air ?ow is to mix a
small percentage by volume of a combustible gaseous
This invention relates to apparatus for initiating and 10 material with air and inject this mixture into an input
controlling combustion in a subterranean formation con
well or borehole in such a manner that this mixture of
taining carbonaceous matter from a borehole penetrating
fuel and air flows through the carbonaceous matter con
the formation.
taining formation toward the ignition well. The ignition
In situ combustion in the recovery of a di?icultly ?ow
well as considered herein is the borehole extending from
able hydrocarbon from underground strata containing
the surface of the ground into the carbonaceous material
such hydrocarbons or carbonaceous material is becoming
containing formation from which the formation is ignited
more prevalent in the petroleum industry. In this tech
in the combustion operation. The injection well or bore
nique of production, combustion is initiated’ in the car
hole is the borehole into which the mixture of air or
bonaceous stratum and the resulting combustion zone is
air and fuel gas is injected into the formation for main
caused to move through the stratum by either inverse 20 taining this combustion. In said copending application,
or direct air drive whereby the heat of combustion of
a mixture of air and fuel gas suitable for maintaining
a substantial proportion of the hydrocarbon in the
continuous combustion within the carbonaceous material
stratum drives out and usually upgrades a substantial
containing formation contained from about one to ?ve
proportion of the remaining hydrocarbon material. By
percent by volume and more desirably from about two
the term “remaining hydrocarbon material” is meant that 25 to four percent of fuel gas by volume. Propane was
hydrocarbon material recovered and which is not con
disclosed as being a preferred fuel gas but other fuel
sumed in the combustion.
gases than propane, for example, ethane or even methane,
The ignition of carbonaceous material in a stratum
that is either pure methane or in the form of natural gas
around a borehole, followed by injection of air through
is sometimes used. It is preferred that the B.t.u. con.
the ignition borehole and recovery of product hydro 30 tent of the fuel gas used in such an operation be rela
carbon in combustion gas through another borehole in
tively high and, for this reason, the use of propane is
the stratum, is a direct air drive process for clfecting in
situ combustion and recovery of hydrocarbons from the
In the drawing, FIGURE 1 is a longitudinal view,
stratum. In this type of operation, the stratum usually
partly in section, of a preferred embodiment of my in
plugs in front of the combustion zone because a heavy
vention. FlGURE 2 is a longitudinal view, partly in
viscous ?uid bank collects in the stratum in advance of
section, of another embodiment of heating apparatus of
the combustion zone and prevents movement of air to
my invention. FIGURE 3 illustrates still ‘another em
the combustion process. To overcome this dit?culty and
bodiment of heater of my invention. FIGURE 4 is a
permit the continued progress of the combustion zone
longitudinal view, partly in section, of still another em
through the stratum, inverse air injection has been re
bodiment of my invention. FIGURE 5 illustrates, in di
sorted to. By this latter technique, a combustion zone
grammatic form, a sectional view through a carbonaceous
is established around an ignition borehole by any suit<
material bearing formation and overlying strata illus
able means and air is fed through the stratum to the
trating a method of initiating combustion within a car
combustion zone from one or more other boreholes.
bonaceous material bearing formation. FIGURE 6 illus
In operating with either direct or indirect air injection 45 trates one method for recovering carbonaceous material
to produce hydrocarbons from a carbonaceous stratum
from a carbonaceous material containing zone being pro
duced by underground combustion.
by in situ combustion, it is necessary to ignite ?rst the
carbonaceous material in the stratum around. a borehole.
Referring to the drawing and speci?cally to FIGURE
Various methods of igniting this carbonaceous material
1, this embodiment of formation heater involves a, tubular
have been devised. Also, many burners have been de 50 outer shell 12 in which is disposed a tubular shell 13
vised for downhole use, such as gas ?red burners and
of smaller diameter than shell 12. These two tubular
electric heaters. One di?'iculty in the use of any of these
shell members are disposed substantially concentrically
types of burners in such downholc operation is that the
with respect to one another and’ at a spaced distance
formation tends to become overheated in the immediate
so as to provide an annulus 23 therebetween. The upper
vicinity of the burner and the remainingrportion of the 55 end of annulus 23 is closed by a closure 27 as illustrated.
borehole through the formation may not. be heated suffi
The bottom ends of shells 12 and 13 are closed as illus
portion between closures 14 and 14a is an easily melt
a downholeeheater of such construction that heat is uni 60 able and boilable metal 20. An upper closure member
formly transferred to the face of the borehole in the
or cover 22 is disposed as illustrated for con?ning com
carbonaceous. material containing formation. Another
bustion gases and directing same to a vent pipe 24.
object of this invention is to provide a heater for heating
Disposed within the inner shell 13 is a burner, that
the formation containing carbonaceous material which
distributes heat of sufficient intensity for ignition or the 65 is, a fuel gas burner which comprises a burner tip 25
surrounded by a burner shield 15. Connected with
carbonaceous matter at all levels’ of the formation face
burner tip 25 are pipes 16 and 17 through which air
exposed in the borehole. A further object of this inven
and fuel gas, respectively, are passed from the surface
tion is to provide a downhole heating apparatus’ which
of the ground. The burner is lit or in other words the
does not overheat at one level and underheat at another
level. Other objects and advantages of my invention 70 fuel gas is ignited vas by a sparltplug 19 energized by an
electric current passed through wires 18 from above
will be realized by those skilled in the art upon con
sideration of the accompanying disclosure.
ground. As is well known in such art, a high voltage
low amperage current is required to operate such an
referred to as an “ignition well.” Such ignition wells
are ordinarily provided with casing, as for example, a
casing 64, which is provided with a head or casing cover
65 at the head of the well. In FIGURE 5 air for
passage to pipe 16 to the burner in the heat transfer
A burner or heat transfer apparatus of this type op
erates in the following manner. Fuel gas and air are
passed downward through pipes 16 and 17, respectively,
assembly is illustrated as being provided from the atmos
and then electric current is passed through wires 18 to
phere by a pump 69 which transfers the air through a
form a spark at spark plug 19 which in turn ignites the
pipe 88 to tubing or pipe 16. A fuel gas from a source,
gas. When the gas has been ignited and ?ame issues
not shown, for ?ring the heater is provided through a
from within burner shield 15, the apparatus then starts
to become heated. The metal 20 in the bottom portion 10 pipe 85 by a pump 67 and through a pipe 86 and a
pipe 89 with valves in these pipes being open, to tubing
of this heater is such a metal as sodium, potassium,
lithium, rubidium, caesium, or a mixture of any two or
more of these metals. Of these metals, caesium boils
at a temperature of 1238“ F. and lithium boils at a
or pipe 17 for passage down the well to the burner.
The heater is operated in this manner until such time
that it is certain that the combustion in the formation
temperature of about 2437° F., these two temperatures
representing the extreme limits of boiling points of these
had been well started and is progressing satisfactorily.
It is preferred to use metallic sodium
Progression of the combustion zone may be observed by
providing a small diameter well bore 74 which may be
in this apparatus because it is less expensive to purchase.
cased by a casing 75, as desired, and which is provided
Metalic sodium boils at a temperature of 1615 ° F. Thus,
with one or more thermocouples 76.
several metals.
These thermocou
upon ignition of the gas at burner 25, the shield directs 20 ples communicate to electrical apparatus above ground
through a cable 77 to conventional electrical apparatus
the ?ame downward against the lower portion of the
for converting electrical impulse to degrees F., for ex
inner shell 13 and at closure member 14a so that the
ample. Such electrical equipment is well known in the
?ame will be directed substantially toward the metal 20.
art. At such a time that thermocouples 76 indicate that
Upon continued heating, the metal is gradually raised to
a temperature approaching its boiling point. When the
the combustion zone has progressed a substantial distance
from the heat input well then the valves in pipes ‘86 and
metal begins to boil, vapor rises upward in annulus 23
89 and in pipe 88 may be closed to shut off the ?ow
and heats the walls of the inner and outer shells 12 and
13, respectively. The wall of the inner shell 13, is, of
of gas and air to the burner in the heat transfer assem
course, quite hot because it is exposed to the temperature
bly. When these valves are closed and the ?ame in the
of the combustion gas. The wall of shell 12, being ad
heat transfer assembly is extinguished, the heat transfer
jacent the carbonaceous material bearing formation is
assembly is pulled from the well by unbolting casing
materially cooler than shell 13. As the vapor of the
metal rises in annulus 23, it condenses mainly on the
surface of shell 12. As the metal shell becomes heated
by condensation of the vapor, the vapor rises higher
up the ‘annulus until ?nally the entire inner surface 21
of shell 12 is in contact with condensing metal vapor
and is thus heated to a sufficiently high temperature. It
cover 65 and pulling the tubes or pipes and the heater
in a conventional manner.
While the heat transfer apparatus is being withdrawn
from well bore 63, air with a small content of fuel gas is
passed through tubing 70 into the air input well 72 for
maintenance of combustion within the formation. In
this passage of the air and gas mixture down tubing
70, the gas is passed under the in?uence of pump 67
is realized by those skilled in the art that such a means
of distributing heat all the way up and down the heater 40 through pipe 85 and pipe 68 with the valve in that pipe
is particularly adapted to heating uniformly ‘an object
to be heated. Thus, by the construction of this apparatus
of such length that it extends in the borehole across the
entire face of the carbonaceous material containing form
ation, the entire surface of the formation becomes heated 45
being open and air from pump 69 is passed through
pipe 87 with the valve in this pipe being open and
the mixture then enters the air inlet pipe 70 for passage
down the well.
After the heat transfer assembly 11 has been with
drawn from the ignition well 63, a production tubing is
carbonaceous material containing formation exposed to
run into the well and is attached to the casing by means
of a casing cover similar to casing cover 65. In FIG
URE 6 is illustrated the well 63 provided with such a
to a desired temperature.
When this surface of the
the borehole becomes sufficiently hot then upon arrival
of air from an adjacent air input well conditions are
right ‘for ignition to begin. As mentioned hereinbefore 50 production tubing 66 attached to the well casing by a
and as fully disclosed in said copending application, by
casing cover 65a. After this tubing 66 is run into the
mixing a small percentage of a combustible gas with the
air being injected into an adjacent air input well upon
ignition of the surface of the carbonaceous material
well ‘and ‘attached to the casing by the cover 65a, com
bustion gases and vaporous hydrocarbon material which
leave the formation and enter well 63 at the borehole
bearing formation exposed to the heater a combustion 55 surface 73 enter tubing 66 and are conducted up the
front travels slowly and radially outwardly from the bore
well. This produced material leaves the well head,
hole into the formation.
passes through a pipe 78 into a separator 79 in which
On reference to FIGURE 5, reference numeral 11
produced liquids separate from produced gas. If de
identi?es such a heat transfer assembly as illustrated in
sired, all or a portion of the produced hydrocarbon ma
FIGURE 1 disposed in a borehole 63 within a carbon
aceous material containing subterranean formation 61.
Pipes 16 and 17 pass air and fuel gas, respectively, to the
burner of the heat transfer assembly and upon igniting
spark plug 19 (FIGURE 1) by passage of a high volt
terial from production tubing 66 is by-passed from pipe
78 ‘and passed through a by-pass line containing a con
denser 90 for condensation of condensable material. This
condenser can be a large surface atmospheric condenser,
or a liquid condenser in which the coolant is a cooling
age current down leads 18 the burner within the heat 65
water or the condenser may even be a refrigerated con
denser. Whatever type of condenser is used, condensed
the heat transfer assembly 11 becomes well heated and
‘and uncondensed materials pass on into separtor tank 79
heating is continued, the surface of the well bore is
in which gases are separated from liquid. Liquid is
raised to a combustion temperature and upon passage of
air or air and a fuel gas down a tube 70 in an air input 70 passed from separator 79 through a pipe 80 into a
storage tank 81 ‘for such disposal as desired. Gases sepa_
well 72 and through formation 61 combustion progresses
rated in separator 79 are withdrawn through a pipe
from borehole 63 in a direction toward borehole 72.
82 and, if desired, a small portion of this produced gas
Reference numeral 62 identi?es the leading surface of
is passed through a pipe 84 into pipe 86 of FIGURE 5
a combustion zone as propagated in the manner just dis
closed. Borehole 63 is in terms of this art frequently 75 and further passed through pipe 68 for use in producing
transfer assembly 11 is lit and heating begins. After
the air-fuel gas mixture for injection into the air input
well. Gas separated in separator 79 and passed through
pipe 82 not required for such combustion maintenance is
withdrawn from the system through a pipe 83 for such
tion, apparatus is so provided that upon closing of a circuit
to solenoid valve 59 and 51 high voltage current is simul
taneously passed to spark plug 53 so that upon passage
of air and fuel gas through tubes 57 and 56, respectively,
to burner ring 52 the spark plug becomes activated and
ignites the fuel gas. Upon ignition of the gas the metal
20 becomes heated and ?nally boils. The operation from
disposal as desired.
In FIGURE 2. is illustrated another embodiment of
heater apparatus involving the principles of my invention.
this point on is similar to that described relative to the
A difference between this heater and the one illustrated
heating apparatus of FIGURES l, 2 and 3. The construc
in FIGURE 1 is in the actual fuel gas burner arrange
ment. The burner illustrated in FIGURE 2 is intended 10 tion of the heater apparatus is slightly different in this
modi?cation of FIGURE 4 than in the other modi?cation.
to utilize a premix air and fuel mixture in place of sep
This difference is that an opening 58 is provided in the
arate fuel gas and air. A premixed mixture of fuel gas
bottom of the heating apparatus for accommodation of
and air is passed from the surface of the ground down the
the electrical wiring. If the electrical wiring cable 54
heat input well or ignition well through a pipe 33 to the
heating’ apparatus. Since the premixed air and fuel is 15 were on the outside of the heat transfer assembly 11 upon
lowering this apparatus down the Well bore the cable
obviously an explosive mixture, a flame arrestor 34 is
might easily be injured so that the electrical portion of
provided in pipe 33 at a point adjacent the heating appara
this apparatus would not function properly. After igni
tus. After passing through the flame arrestor 34 the mix
ture enters the actual heating apparatus and ?ame then
tion of gas in burner ring 52, it is immaterial whether
passes through a ?ame tube 36 provided with openings 20 the wiring at this point is destroyed or not because it has
ful?lled its purpose. Furthermore, burned gases from
32 only at and near the lower end of the ?ame tube 36.
the ?ame issuing from burner 52 pass upward through
Flame is needed only in the general vicinity of the liquid
opening 58 and impart additional heat to the inner wall of
metal 20 in the bottom portion, of the heater. Heat
the inner shell 13 and these burned gases ?nally exit up
issuing through the openings 32 in this lower portion of
?ame tube 36 heats the metal to a boiling temperature 25 the well through vent pipe 55 for such disposal as desired.
Materials of construction for use in building the heat
and upon boiling the vapor rises up the annulus 23 and
ing apparatus of my invention may be selected from
condenses mainly on the walls of the outer shell 12 for
among those commerically available taking into consider
imparting heat to the formation to be ignited. The com
ation the particular metal 20 heated to boiling within the
bustible mixture of gas and air is ignited by spark plug
19 energized by high voltage current through leads 18 30 apparatus and further taking into consideration tempera
tures involved. Some stainless steels withstand tempera
as mentioned hereinbefore. The vent pipe 24 is pro
tures in the vicinity of 2600 to 2700" F. Such materials
vided for passage of burned gases up the well bore to
might be expected to withstand temperatures within the
the surface of the ground for disposal.
ignition wells maintained for the length of time required
In FIGURE 3 is illustrated an embodiment of heater
of my invention which is heated by electrical means in 35 to start combusion in the formation.
Referring again to FIGURE 4 the air containing bottle
place of a fuel gas. The main heating portion of the ap
46 is ?xed to case 45 by support 48 while the fuel gas
paratus that is the inner and outer shells 13 and 12, respec
bottle 47 is attached by member 49 to case 45.
tively, forming an annulus in the bottom of which is a
In FIGURE 2, cover 35 is provided for con?ning com
quantity of boilable metal, is all similar to that illustrated
bustion gases from burner tube 36 so as to direct them
in FIGURES 1 and 2. For heating the metal in this em
up the vent pipe 24.
bodiment, a heating coil 40 is wound around the inner
In each case or type of heater described herein it is
wall of the inner shell 13 and is held in place by a refrac
necessary and important that the length of the actual heat
tory cementing material 41, such as Kaocast, a, high
transfer portion of the apparatus be at least equal to the
alumina, castable, hydraulically setting refractory. The
electrical heating element may be maintained or held in 45 length of the borehole in the carbonaceous material hear
ing formation. In other words, the length of the heater
close contact with the inner wall of shell 13 in any other
should be at least equal to the thickness of the carbona
suitable manner, if desired. Lead wires 42 conduct elec
ceous material containing formation for uniform heating to
tric current from the surface of the ground down the well
combustion temperatures of the material in the formation.
bore to the resistance element 40. As the metal 20 is
By so providing this heater and with its unusually uniform
heated to its boiling point vapor than passes upward in
distribution of heat throughout its length hot spots and
the annulus 23 to heat the Walls of the outer shell 12 for
spots heated to too low a temperature are not involved.
bringing to combustion temperature carbonaceous matter
on the borehole walls of the formation.
A cover 91 is
provided at the top of this apparatus to provide support
for wires 42.
As is well known, portions of formations which are over
heated frequently become sintered and more or less im
Cover 91 is provided with a vent 90 for 55 previous to the passage of ?uid.
inlet and outlet of gases of expansion formed during
heating and cooling of this apparatus.
In FIGURE 4 is still another embodiment of my in
Furthermore, spalling
and caving due to excessive temperatures or partial fusing
are not involved.
Certain modi?cations of the invention will become
apparent to those skilled in the art and the illustrative
combustion of a fuel gas with air. However, in place 60 details disclosed are not to be construed as imposing
unnecessary limitations on the invention.
of having to provide one or more tubes or pipes for pas
I claim:
sage of premixed air and fuel or air and fuel separately
1. Apparatus for heating a subterranean formation con
from the surface of the ground down to the heating
taining carbonaceous matter from a bore hole penetrating
apparatus I provide bottles of fuel gas and air under
vention. In this embodiment, heat is again supplied by
pressure with the apparatus. As illustrated in this ?gure 65 said formation comprising, in combination, a ?rst tubu
lar member having the lower end thereof closed, a sec
a case 45 is attached to the lower portion of the outer
ond tubular member having the lower end thereof closed
shell 12. Case 45 houses a burner ring 52 which is con
disposed within and along the axis of said ?rst tubular
nected by tubes 56 and 57, respectively, to a fuel gas
member, said second member being disposed at a spaced
bottle 47 and to an air bottle 46. Tube 56 is provided
with a solenoid valve 51 while tube 57 is provided with a 70 distance from said first member thereby providing an
annulus therebetween having completely closed ends, a
solenoid valve 50. These solenoid valves are operated
body of metal having a boiling point between about l200°
from the surface of the ground by passage of electrical
impulse through electrical cable 54. Additional wires are
and 2450° F. disposed in and partially ?lling said an
provided in cable 54 for transmission of high voltage
nulus at a lower end thereof, said body of metal being
current to a spark plug 53. In the aboveground opera 75 present in an amount sui?cient upon boiling to substan
tially vaporize and ?ll said annulus with condensing
annulus thcrebetween, a body of metal having a boil
metal vapor, a closure member closing the end of said
second tubular member at an upper end of said annulus,
ing point between about 1200° and 2450° F. disposed in
metal which is so adapted as to provide a combustion
area in a position adjacent to the lower end of said an
and partially ?lling said annulus at one end thereof, said
body of metal being present in an amount su?‘icient upon
boiling to substantially vaporize and ?ll said annulus with
condensing metal vapor, and means for heating said metal
nulus and said body of metal so as to effect vaporization
by an upper portion of said tubular member so as to
of same, and a vent in said closure member and in com
munication with said combustion area.
heating being external said annulus and adjacent said
means supported by said closure member for heating said
effect vaporization of said body of metal, said means for
2. The apparatus of claim 1 wherein said metal is 10 body of metal in same.
7. In the apparatus of claim 6, wherein said means
for heating said metal is a gas fueled burner disposed
lithium, rubidium, cesium, and mixtures of two and more
within said second tubular member, a conduit commu
of these metals.
nicating with said burner and extending through said
3. The apparatus of claim 1 wherein said means for
heating said metal is a gas fueled burner.
15 closure member for passage of premixed fuel gas and
gaseous oxygen to said burner, a ?ame arrestor in said
4. The apparatus of claim 3 wherein said gas fueled
conduit, and means to ignite fuel gas in said burner.
burner for heating said metal is disposed within the inner
of said ?rst and second tubular members, and said burner
References Cited in the ?le of this patent
being so positioned as to direct ?ame downward.
5. The apparatus of claim 3 wherein said axis is ver 20
tically disposed and said closure member is at about the
Colby _______________ __ July 13, 1915
top of the apparatus and wherein said gas fueled burner
Smith _______________ __ Aug. 16, 1927
is disposed outside the outer tubular member of the ?rst
Knox _______________ __ Jan. 12, 1932
and second tubular members and below the lower closure
selected from the group consisting of sodium, potassium,
means of said separate closure means, a separate vent in 26
said lower closure means and in said closure member,
?rst and second bottles for fuel gas and a combustion
supporting gas, respectively, supported by and below said
burner, separate conduit means communicating said ?rst
and second bottles with said burner, separate valves in 30
each conduit means for opening said valves and means
for igniting fuel gas in said burner.
6. Apparatus for heating a subterranean formation
containing carbonaceous matter from a bore hole pene
trating said formation comprising, in combination, a ?rst 35
tubular member, a second tubular member disposed with
in and along the axis of said ?rst tubular member, said
second member being disposed at a spaced distance from
said ?rst member thereby providing a completely closed
Mikeska ______________ __ Dec. 4, 1934
Houdry ______________ __ June 27, 1939
Smith ______________ __ June 12, 1951
Merriam et al. ________ __ Feb. 5,
Riddiford et a1. _______ __ Feb. 16,
Maher et al. _________ __ Sept. 13,
Kobayaski ___________ -_ Jan. 14,
Dwyer ______________ __ Dec. 23,
Bell _________________ __ July 7,
Salomonsson et a1 ______ __ Sept. 1,
Stegemeier __________ .. Apr. 12,
France _____________ __ Nov. 14, 1936
France ______________ __ Dec. 22, 1944
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