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Патент USA US3044557

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July 17, 1962
Filed Dec. 29, 1958
. mmvm1|8
United States
Robert C. Pryor, Bartlesville, Okla., assignor to Phillips
Petroleum Company, a corporation of Delaware
Filed Dec. 29, 1958, Ser. No. 783,500
. 9 Claims.
(Cl. 166-59)
R 3,644,551
Patented July 17, 1962
apparatus which prevents overheating of the apparatus.
Other objects of the invention will become apparent upon
consideration of the accompanying disclosure.
The heater of the invention is an improvement in the
heater of the above-identi?ed application in providing a
constriction in the burner between the combustion cham
lber and the exhaust conduit whereby the combustion gases
This invention relates to gas ?red heaters for heating
are given a jetting action to increase the turbulence in the
exhaust conduit of the heater with better heat distribu-v
In situ combustion in tthetrecovery of hydrocarbons 10 tion and more uniform heating of the conduit. This
from underground strata containing carbonaceous ma
improvement makes it possible to utilize a longer exhaust
terial is becoming more prevalent in the petroleum in
conduit on the heater between the constricted area and
dustry. In this technique of production, combustion is
the turn at the bottom of the heater for heating a longer
initiated in the carbonaceous stratum ‘and the resulting
section of stratum.
comlbustion zone is caused to move thru the stratum by 15
In a second embodiment of the heater of the. invention
either inverse or direct air drive whereby the heat of
the heater per se is constructed in a similar manner but
combustion of a substantial proportion of the hydrocar
the lower end of the exhaust conduit is open to! the bore;
bon in the stratum drives out ‘and usually upgrades a sub
hole so that the hot combustion gases pass upwardly
stantial proportion of the remaining hydrocarbon material.
thru the annulus between the heater and the boreholewall
a well bore.
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 by
drocarbons and combustion gas thru another borehole in
and are vented thru the Well head. 7 In either embodi
ment the jetting of the exhaust gases into the tail pipe
of the heater (exhaust conduit) provides more uniform
heating than can be obtained without the jetting cited
and also permits the use of a longer tail pipe, thereby
the stratum, is a direct lair drive process for effecting in
situ combustion and recovery of hydrocarbons from the 25 adapting the heater to use in the heating of thicker strata
stratum. In this type of operation the stratum fre
than without this feature of the invention.
quently plugs in front of the combustion zone ‘because
A more complete understanding of the invention may
a heavy viscous fluid bank collects in the stratum in ad
be had by reference to the accompanying schematic draw
vance of the combustion zone which prevents movement
ing of which FIGURE 1 is an elevation of one embodi
of air to the combustion process. To overcome this
ment of the downhole heater of the invention positioned
di?’iculty and permit the continued progress of the com
in a borehole adjacent a carbonaceous stratum with the
bustion zone thru the stratum, inverse an injection has
auxiliary ‘apparatus for initiating combustion in a car
been resorted to. By this technique, a combustion zone
bonaceous stratum; FIGURE 2 is an elevation, partly in
is established around an ignition borehole by any suitable
section, of one embodiment of the burner of the invention;
means and air is tied thru the stratum to the combustion 35 and FIGURE 3 is an elevation showing another embodi
zone from one or more surrounding boreholes.
ment of a downhole heater in a borehole with auxiliary
In operating with either direct or indirect air injec
tion to produce hydrocarbons from a carbonaceous stra
Referring to FIGURE 1, a carbonaceous stratum 10
tum by in situ combustion it is necessary to ?rst ignite
is penetrated by a borehole 12 in which is positioned a
the carbonaceous material in the stratum around a bore 40 casing 314 closed at the top by well head 16. Conduits 18
hole therein. One method of ignition utilizes a down
and 29 are provided for introducing combustion air and
hole heater either of the electric or gas ?red type. Elec
for withdrawing produced gases, respectively, from the
tric heaters have been found difficult to design to with
‘casing. Heater 22 is suspended in Iborehole 12 within
stand the downhole heat and have also been rather slow
stratum 10 and is of a length substantially corresponding
in heating the formation up to combustion supporting
to the thickness of the stratum. The heater is suspended
by means of conduits 24 ‘and 26. Conduit 24 contains a
In a ‘carbonaceous stratum of substantial thickness, such
concentric inner conduit or burner feed line 28 which
as 25 or 30 feet and more, it has been found di?’icult to
is supplied with a combustible mixture of fuel gas and
ignite the entire thickness of stratum with available gas
air by means of lines 3i} and 32, respectively, which
heaters. The copending application of A. S. Rogers et 50 connect with a mixing valve 34. A coolant supply line
221., SN. 719,890, ?led,‘ March 7, 1958, discloses a gas
36 connects with the annulus between conduit 24 and feed
line 28.
?red heater which avoids a number of the disadvantages
of prior art heaters and is adapted to heat relatively thick
Referring to FIGURE 2, the heater 22 includes a burner
strata for ignition purposes. The present invention is con
comprising a metal shell 42 in the form of a cylinder or
cerned with an improvement in the heater disclosed in the
tube, an elongated tubular refractory liner converging
aforesaid application.
toward each end from an intermediate cylindrical section
Accordingly, it is an object of the invention to provide
41 by means of frusto-conical sections 43 and 45. The
a downhole heater of such construction that the adjacent
space between the liner and the shell is ?lled with a
borehole can be adequately heated to combustion sup 60 ceramic material 44. The liner forms a downwardly ?ared
combustion zone 46. Insulating material 44 may com
porting temperature without contacting the Wall of the
prise any suitable highly refractory ceramic material such
borehole with combustion gas from the heater and with
as Babcock Wilcox Company’s “Kaokast” or Johns-Man
out overheating the conduit on which the heater is sus
ville’s “3X Firecrete”. These materials are'mixed with
pended. Another object is to provide a downhole heater
which effects better gas turbulence and heat distribution 65 water to form a plastic mud or mortar which is intro
duced into shell 42 on which it is held by stainless steel
in the exhaust conduit leading from the heater. It is also
an object of the invention to provide a downhole heater
which is effective in heating a stratum upwards of 25
or 30 feet in thickness. Another object of the inven
rods 43 welded to the shell at the outer ends. Rods
43 may be omitted if desired as shown in FIGURE 3.
The upper end of burner 42 is closed by plate 50 thru
which feed line 28 passes into the inlet end of theburner.
tion is to provide a downhole heater of high e?iciency 70 A ?ame arrester 52 is positioned in the end of feed line
for initiating in situ combustion in a carbonaceous‘stra
2-8 to prevent burning of the combustible mixture there
tum. A further object is to provide downhole heating
in. An ign-iter comprising a heating coil 54 positioned in
meter and 8 inches long. The frusto-conical section at
the exhaust end of the burner was 9 inches long and
l2%4 inches in diameter at the exhaust outlet. The shell
' a ‘the teed end of the burner is connected by insulated con
ductors 56 with a suitable electric current source ‘at the
surface, such as battery 55, thru switch 57. Section 45
of the liner converges to an outlet/conduit 47 which coin
cides with an opening 49 in lower end plate '51.
An exhaust conduit ‘:26 makes a U-turn or a turn of
180° and connects with the exhaust end of heater 4%
of the ‘burner was a 16 gauge 304 stainless steel tube
by means of conduit 58. A conduit 60 connects the an
221/2 inches long forming a sleeve around the lower end
of the gas injection conduit. The insulating material was
poured into the annulus betweenrthe shell and the liner
without the aid of lugs illustrated in FIGURE 2 and com
nulus around conduit 28 with exhaust conduit 26 just
prising Kaokast. A 10 foot long tail pipe 31/2 inches in
abovev the heater to provide ?ow of coolant therebetween.
diameter open at the exhaust end was utilized.
Conduit 60 has an upturned end to jet coolant into the
exhaustgases and enhance their ?ow out of conduit 26.
FIGURE 3 illustrates an embodiment of the invention
wherein burner 22 is open to the borehole thru after
[burner or tail pipe 58. Line 20 includes a back pressure
control valve 70- to regulate the back pressure on the
combustion gas being vented thru line 20. Line 18 is
were run on this burner and on a burner without a con
striction in the exhaust line downstream of the com
bustion zone at an input rate of’ approximately 300,000
B.t.u. per hour. Thermocouples were positioned at regu
lar spaced intervals along the tail pipe or afterburner of
each burner at 6 points numbered from adjacent the
burner to the downstream end of the tail pipe. The tem
peratures obtained in the two runs are set forth in the
provided for injection of air to‘ initiate combustion of
table below.
the hot stratum 10 after ignition temperature has been
In utilizing the apparatus of FIGURES 1 and 2 in
initiating in situ combustion, fuel, gas is burned in com
bustion zone 46 andv the hot combustion gases heat the
burner shell 42 and conduit 58 adjacent the stratum and
the combustion and heating are continued 'until'the tem 25
perature of the stratum is raised to the ignition point of
the carbonaceous material in the stratum and, at this
time, air or other O2-containing gas is brought into con
tact with the hot stratum so that ignition takes place.
[Temperature ° F.]
7 Temperature
Heater A _______ __
Heater B _______ _ _
l, 290
l, 300
1, 285
l, 300
l, 300
l, 310
pipe. The more uniform heating along the tail pipe of
heater B demonstrates the advantage of this type of
burner for use in heating thick carbonaceous strata for
the purpose of initiating in situ combustion therein.
Certain modi?cations of the invention will become ap
parent to those skilled in the art andthe illustrative de
in. After initiation of combustion by direct air injection
and establishment of a substantial combustion area, in
yerse air injection is readily instituted by cutting off the
?ow of direct air thru line 18 and injecting air thru the
tailsdisclosed are not to be construed as' imposing un
stratum to the combustion area from air injection bore
necessary limitations on the invention.
When utilizing either direct or inverse air injection to
initiate the combustion of carbonaceous material around
‘borehole 12, the burner is withdrawn from the borehole
after combustion is well established. Borehole 12 be
comes a production borehole during inverse air injection
thru one or more surrounding air injection boreholes and
production is removed thru line 20 or thru tubing in
serted thru well head 16, by conventional means. Dur
In the table heater A represents the burner without the
constriction in the exhaust line while heater B represents
the heater of the invention utilizing a constriction in the
burner between the combustion zone proper and the tail
When ignition by direct injection is practiced, air is intro
1 Thermocouple out of order.
duced thru line 18 to initiate and sustain the combustion
and when the ignition is by inverse air injection, air is in
jected thru the stratum from a ring of boreholes therein
so that it arrives at the hot section of stratum adjacent
borehole 12 and initiates and sustains combustion there» 35
holes positioned close by.
I claim:
1.,Apparatus for heating an earth borehole within a
carbonaceous stratum to combustion temperature com
prising in combination an elongated tubular burner in
cluding an intermediate cylindrical section, an upper
frusto-conical section converging from said cylindrical
section to a gas inlet, a ?ame arrester in said gas inlet,
and a lower trusts-conical section converging from said
ing direct injection in situ combustion, borehole 12 50 cylindrical section to an exhaust outlet of substantially
serves as an air injection borehole and produced hydro
canbons and combustion gases are removed from sur
rounding boreholes by conventional means. .
When utilizing the burner of FIGURE 3, the com
‘bustion gas may be vented thru line 20 under any desired
back pressure regulated by adjusting valve 70 or any
.portion or all of the hot combustion gas may be driven
lesser diameter than said cylindrical section; a down
wardly extending elongated exhaust conduit of sub
stantially larger diameter than said exhaust outlet con
nected therewith, said exhaust outlet forming a constric
tion in the gas passageway from said burner into said
exhaust conduit to impart jetting action to exhaust gases
passing into said conduit and establish turbulence therein;
an igniter in said burner; and conduit means connected
with said gas inlet for supplying fuel and combustion
spaced to the ignition ‘borehole. This manner of oper
ating; may be utilized only in strata where plugging does 60 supporting gases thereto.
2. The apparatus ‘of claim 1 including a U-turn on
not readily occur. In strata of this type where plugging
the exhaust end of said exhaust conduit and an upwardly
does occur hot combustion gases are vented thru line 20.
extending conduit parallel to and extending above said
:In the event hot combustion gases are driven thru the
stratum, combustion is initiated when the stratum im
rmediately surrounding borehole 12 reaches ignition tem 65 3. The apparatus of claim 1 wherein said burner is
thru the stratum to one or more boreholes therein closely
perature by injecting air thru line 18, forcing the com
bustion-supporting air down the annulus and into contact
'with the hot stratum. During this phase of the process,
‘combustion in burner 22 may be continued, diminished,
or completely terminated, depending upon the temper 70
atureto which the stratum is heated before air injection
is commenced.
encased in insulating material.
4. The apparatus of claim 1 wherein said burner is
positioned in a well bore adjacent a carbonaceous
stratum; said conduit means comprises a tubing string ex
tending thru a well head; and including exhaust means
thru said well head.
5. The apparatus of claim 4 including a pipe string
concentric with said tubing string providing an annulus
>A burner was constructed substantially as shown in '
therewith for ?ow of ‘coolant substantially to the upper
FIGURE 2- utilizing a nickel chrome alloy liner 20 inches
long. The intermediate section was 27/8 inches in dia 75 end of said burner; a crossover conduit from'said pipe
3,044,55 1
string to said exhaust means adjacent said burner, termi
nating in an upwardly directed end section, said exhaust
means comprising a conduit of substantially the diameter
of said exhaust conduit and extending from same thru
saidwell head.
6. The apparatus of claim 4 wherein said exhaust con
duit opens into said well bore at a lower level of said
stratum and exhaust gases pass upwardly thru the an
larger diameter than said exhaust outlet connected with.
said outlet and coaxial with said tubular liner.
8. The burner of claim 7 including a U-turn conduit
on the exhaust end of said exhaust conduit; and an ex-]
haust Igas withdrawal conduit connected with the open
end of said U-turn conduit, extending back along said
9. The burner of claim 7 including an insulating
nulus around said tubing string to the exhaust means thru
ceramic covering encasing said liner.
said well head.
7. A burner for downhole heating comprising an elon
References Cited in the ?le of this patent
gated tubular refractory liner of diminishing transverse
cross sectional area each direction along its axis from an
intermediate section to a combustible gas inlet at one
end and to an exhaust gas outlet at the opposite end;
a ?ame arrester in said inlet whereby the upstream sec
tion of said liner forms the initial section of the com
bustion zone of said burner; igniter means for said
burner; and an elongated exhaust conduit of substantially
Kreager _____________ __ May 3, 1927
Levey _____________ __ Nov. 20, 1934
Stalego _____________ __ Nov. 22, 1949
Parker ______________ __ June 18, 1957
Riedel _______________ __ Mar. 4, 1958
Priester _____________ __ May 19, 1959
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