CA1175346A - Indirect firing downhole steam generator - Google Patents
Indirect firing downhole steam generatorInfo
- Publication number
- CA1175346A CA1175346A CA000376784A CA376784A CA1175346A CA 1175346 A CA1175346 A CA 1175346A CA 000376784 A CA000376784 A CA 000376784A CA 376784 A CA376784 A CA 376784A CA 1175346 A CA1175346 A CA 1175346A
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- Prior art keywords
- steam generator
- downhole
- downhole steam
- tube
- steam
- Prior art date
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Abstract
Abstract of the Disclosure A fuel and air downhole steam generator 10 comprises an injector assembly 12 coaxially connected to the top end 14 of the combustion chamber 18. The combustion chamber 18 is connected at its bottom end 20 to the top of the heat exchanger 24. Heat exchanger 24 ends with a means for venting combustion products which comprises exhaust gas turnaround 26 and flow guide 28.
The entire downhole steam generator 10 is completed with steam deployment means which comprises a stab-in-tube 30 disposed to receive the output of the heat ex-changer 24.
The entire downhole steam generator 10 is completed with steam deployment means which comprises a stab-in-tube 30 disposed to receive the output of the heat ex-changer 24.
Description
~:~L75~
INDIRECT FIRING DOWNHOLE STEAM GENERATOR
W.R. Wagner D.E. Wright John Campbell, Jr.
Back~round of the Invention l. Field of the Inventlon This invention pertains to steam generators and more speclfically to downhole steam generators for generating high pressure steam at the bottom of oil well bores.
INDIRECT FIRING DOWNHOLE STEAM GENERATOR
W.R. Wagner D.E. Wright John Campbell, Jr.
Back~round of the Invention l. Field of the Inventlon This invention pertains to steam generators and more speclfically to downhole steam generators for generating high pressure steam at the bottom of oil well bores.
2. Desc_iption of the Prior Art The use of steam for recovering crude oil was initia~ed in the United States in 1960. It found its first use in the stimulation of wells drilled into reservoirs containing low grav~ty crude oils. Its use throughout CalifQrnia~increased rapidly until, by the mid~sixties, the production of oll 15 ~ ;by~steam stimulat10n exceeded 100,000 barrels a day.
Steam~stiDulation involves the injection of steam into a producing well for a relatively short period of time, a few days to a month or so, allowing the~well to "soak" for several days or a week or two, and then returning the well to production. The steam generator is then used for injection into a 20 ~ ~second well and, in turn a thlrd or fourth, etc. Typically, wells arest1mulated once every three months to once every year. To facilltate such operation, the steam genera~or was usually sk~d-mountedl or the steam was piped to several nearby wells that it would supply in turnO
Steam stimulation, because of the rapid production following upon the ~25 expenditure for generating steam, is an intrinsically profitable operation.
The amount of oil that can be recovered from a reservoir is limited by the fact that the reach of such a technlque into the reservoir is limited.
~l~l'7~3~
As the oil ~s heated and dralned from the zone immediately around the well bore, subsequent influx of oil is l~mited by the flow of oll from the reservo1r into the zone around the well bore, The steam drive has been developed as an addltional or supplementary operation to the steam soak to achleve a greater overall recovery efficiency of crude oll from the reservoir. In the steam drive, steam is injected into alternate wells (drilled in a repeating pattern) and the oil ls dlsplaced by the lnjected steam into the offsetting wells. Field operations have conf~rmed the earlier physlcal model studles that recovery can exceed 50%
of the original o~l in place, but at lower oil/steam ratios than those achieved in steam soak operations. The lower oil/steam rat~os arise from the fact that a signlflcantly greater fraction of the lnjected heat 1s lost ; because of the larger time of contact and contact area between the swept reservoir zone and the adjacent base and cap rocks.
lS Production of crude oil by steam stimulatlon and steam drive had reached some 200,000 barrels a day by 1978. These enhanced oll recovery processes are the only ones, over and above water flooding, that have proved to be economically successful to date.
The use of~steam iniection has been lim~ted to date to heavy oil reser-voirs that conta~n a very h~gh saturation of oil, not having been depleted significantly by primary operatlons and water flooding. The latter, of course9 is not applicable in these heavy oil reservoirs because of very adverse mobil~ty ratio. The high oil saturat70n has been requlred so that the recovery of crude oil is sufficient to secure a signif1cant sales volume after provlslon of the fuel requlrements for steam generation.
~L3L'~ 3 ~
Recently, attention has been placed on the ex~ension of the steam drlve to reservolrs that have been prev~usly considered poor candidates for the process. The limlts on the applicabll1~y of the steam drive arise essentially from a conb~nation of clrcumstances that lead to low oil/steam ratios (oil produced/steam iniected): too low an oil saturation (insufflcient energy ~s recovered from the reservolr to provide a profitable sales volume after deductlng fuel requirements), too thin a reservoir (proport10nately greater fractional losses of heat to base rock and cap rock), and too deep and too high a reservo1r pressure (high heat losses in ~he wall tubulars and low s~eam quality at the sand face) are the principal factors limitlng the extension of this scheme to crude oil reservoirs not currently amenable the the process.
This ~nvention is aimed at removing the restraint imposed by depth and ~ ~ reservoir pressure on the ef~iciency of the steam drive operation~
; ~ ;15 In current steam driYe operations, an average reservoir depth might be considered to be about 1000 feet trang1ng from 500 to 2000 feet~ and average lnJection pressures somewhat between 300 and 400 psi (ranging from S0 ps1 to 500 pst). Injection rates range from 500 to 2000 barrels of water converted to steam) per day, and the steam leaves the generators at a quality 2~0~ of 70%~to 80%. Heat losses between the generator and the sand face may run about 10% (after equil1br1um cond~tions become establ1shed in the bore hole), and the result is that the quality of the steam is reduced to some 60%
at the sand face. H~wever~ if higher pressures are required to be able to 1n~ect the stesm into higher pressure, deeper, reservoirs, then due to the fact that heaS losses in the ~greater length of well tubulars wlll be still greater than in today's convent10nal applicatlons~ and because the latent heat per pound of steam decreases as the sensible hea~ per pound increases with pressure, the quality o~ the steam at the sand face may fall to 40% or less.
~ ~53~;
Theoretical studies indicate that the displacement efficiency of steam increases as the steam quality entering the reservoir increases. This conclusion can be reached intuitively once it is realized thatthe residual oil satura-tion in a steam-filled porous medium is quickly reduced to values less than 10% of the pore volume, whereas the resi-dual saturations t~ hot water are far higher (25~ to 50%) and are approached only gradually. Field studies have corroborated the superiority of steam drives over hot water drives.
Thus, a technically successful downhole steam generator would provide the advantages of lower heat losses in surface and downhole tubulars and a higher steam quality at the sand face. Capital and operating costs could offset these bene-lS fits and, therefore, it is the goal of this invention to provide the design of a suitable downhole steam generator that will have a positive economic ratio i.e., benefits greater than costs.
Accordingly, there is provided by the subject invention a downhole steam generator suitable for use in a downhole ::
location in a well casing, comprising an injector assembly;
means for conveying combustion ingredients to said injector assèmbly;` a shell comprising hollow or tubular walls for conveying fluid therethrough, said shell forming a combustion ; 25 chamber disposed so as to receive the output of said injector assembly and a heat exchanger, disposed so as to receive ~he output of said combustion chamber; means for introducing water into said hollow or tubular walls of said shell; means for venting combustion products from said shell; a flow guide, positioned pxoximate to said venting means for directing the vented combustion products up said well casing and along the ~.5~7~3~6 exterior of said shell; and means for discharging steam generated within said hollow or tubular walls of said heat transfer chamber at said downhole location.
One downhole steam generator in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which:-Fig. la is a partially cutaway perspective view of thedownhole steam generator.
Fig. lb is a pictorial view of the downhole steam generator showing approximate proportions;
Fig. 2a is a longitudinal cross-sectionof the downhole steam generator;
Fig. 2b is a transverse cross-section of the downhole steam generator taken along line B-B;
Fig. 2c is a cross-sectional view of the downhole steam generator taken along line C-C.
. .....
: ~:
Fig. 2d is a cross-sectional view of the downhole steam generator taken along llne D-D.
Fig. 2e is a cross~sectional vlew of the downhole steam generator taken along line E-E.
5 ~ Descriptlon of the Preferred Embodiments Referrlng now to Fig. la, there is shown a partially cutaway perspective vlew of the downhole steam generator (DSG) generally designated lO. Basically, the DSG lO comprises an injec~or assembly generally deslgnated 12 coaxially connected to the top end 14 of a first cylindrical tube bundle 16 which forns the~shell of a comhust~on chamber 18. Although the precise number and size of the heat exchanger tubes is determined according to specific design require-ments, in its preferred conflguration tube bundle l6 compr~ses forty-s~x
Steam~stiDulation involves the injection of steam into a producing well for a relatively short period of time, a few days to a month or so, allowing the~well to "soak" for several days or a week or two, and then returning the well to production. The steam generator is then used for injection into a 20 ~ ~second well and, in turn a thlrd or fourth, etc. Typically, wells arest1mulated once every three months to once every year. To facilltate such operation, the steam genera~or was usually sk~d-mountedl or the steam was piped to several nearby wells that it would supply in turnO
Steam stimulation, because of the rapid production following upon the ~25 expenditure for generating steam, is an intrinsically profitable operation.
The amount of oil that can be recovered from a reservoir is limited by the fact that the reach of such a technlque into the reservoir is limited.
~l~l'7~3~
As the oil ~s heated and dralned from the zone immediately around the well bore, subsequent influx of oil is l~mited by the flow of oll from the reservo1r into the zone around the well bore, The steam drive has been developed as an addltional or supplementary operation to the steam soak to achleve a greater overall recovery efficiency of crude oll from the reservoir. In the steam drive, steam is injected into alternate wells (drilled in a repeating pattern) and the oil ls dlsplaced by the lnjected steam into the offsetting wells. Field operations have conf~rmed the earlier physlcal model studles that recovery can exceed 50%
of the original o~l in place, but at lower oil/steam ratios than those achieved in steam soak operations. The lower oil/steam rat~os arise from the fact that a signlflcantly greater fraction of the lnjected heat 1s lost ; because of the larger time of contact and contact area between the swept reservoir zone and the adjacent base and cap rocks.
lS Production of crude oil by steam stimulatlon and steam drive had reached some 200,000 barrels a day by 1978. These enhanced oll recovery processes are the only ones, over and above water flooding, that have proved to be economically successful to date.
The use of~steam iniection has been lim~ted to date to heavy oil reser-voirs that conta~n a very h~gh saturation of oil, not having been depleted significantly by primary operatlons and water flooding. The latter, of course9 is not applicable in these heavy oil reservoirs because of very adverse mobil~ty ratio. The high oil saturat70n has been requlred so that the recovery of crude oil is sufficient to secure a signif1cant sales volume after provlslon of the fuel requlrements for steam generation.
~L3L'~ 3 ~
Recently, attention has been placed on the ex~ension of the steam drlve to reservolrs that have been prev~usly considered poor candidates for the process. The limlts on the applicabll1~y of the steam drive arise essentially from a conb~nation of clrcumstances that lead to low oil/steam ratios (oil produced/steam iniected): too low an oil saturation (insufflcient energy ~s recovered from the reservolr to provide a profitable sales volume after deductlng fuel requirements), too thin a reservoir (proport10nately greater fractional losses of heat to base rock and cap rock), and too deep and too high a reservo1r pressure (high heat losses in ~he wall tubulars and low s~eam quality at the sand face) are the principal factors limitlng the extension of this scheme to crude oil reservoirs not currently amenable the the process.
This ~nvention is aimed at removing the restraint imposed by depth and ~ ~ reservoir pressure on the ef~iciency of the steam drive operation~
; ~ ;15 In current steam driYe operations, an average reservoir depth might be considered to be about 1000 feet trang1ng from 500 to 2000 feet~ and average lnJection pressures somewhat between 300 and 400 psi (ranging from S0 ps1 to 500 pst). Injection rates range from 500 to 2000 barrels of water converted to steam) per day, and the steam leaves the generators at a quality 2~0~ of 70%~to 80%. Heat losses between the generator and the sand face may run about 10% (after equil1br1um cond~tions become establ1shed in the bore hole), and the result is that the quality of the steam is reduced to some 60%
at the sand face. H~wever~ if higher pressures are required to be able to 1n~ect the stesm into higher pressure, deeper, reservoirs, then due to the fact that heaS losses in the ~greater length of well tubulars wlll be still greater than in today's convent10nal applicatlons~ and because the latent heat per pound of steam decreases as the sensible hea~ per pound increases with pressure, the quality o~ the steam at the sand face may fall to 40% or less.
~ ~53~;
Theoretical studies indicate that the displacement efficiency of steam increases as the steam quality entering the reservoir increases. This conclusion can be reached intuitively once it is realized thatthe residual oil satura-tion in a steam-filled porous medium is quickly reduced to values less than 10% of the pore volume, whereas the resi-dual saturations t~ hot water are far higher (25~ to 50%) and are approached only gradually. Field studies have corroborated the superiority of steam drives over hot water drives.
Thus, a technically successful downhole steam generator would provide the advantages of lower heat losses in surface and downhole tubulars and a higher steam quality at the sand face. Capital and operating costs could offset these bene-lS fits and, therefore, it is the goal of this invention to provide the design of a suitable downhole steam generator that will have a positive economic ratio i.e., benefits greater than costs.
Accordingly, there is provided by the subject invention a downhole steam generator suitable for use in a downhole ::
location in a well casing, comprising an injector assembly;
means for conveying combustion ingredients to said injector assèmbly;` a shell comprising hollow or tubular walls for conveying fluid therethrough, said shell forming a combustion ; 25 chamber disposed so as to receive the output of said injector assembly and a heat exchanger, disposed so as to receive ~he output of said combustion chamber; means for introducing water into said hollow or tubular walls of said shell; means for venting combustion products from said shell; a flow guide, positioned pxoximate to said venting means for directing the vented combustion products up said well casing and along the ~.5~7~3~6 exterior of said shell; and means for discharging steam generated within said hollow or tubular walls of said heat transfer chamber at said downhole location.
One downhole steam generator in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which:-Fig. la is a partially cutaway perspective view of thedownhole steam generator.
Fig. lb is a pictorial view of the downhole steam generator showing approximate proportions;
Fig. 2a is a longitudinal cross-sectionof the downhole steam generator;
Fig. 2b is a transverse cross-section of the downhole steam generator taken along line B-B;
Fig. 2c is a cross-sectional view of the downhole steam generator taken along line C-C.
. .....
: ~:
Fig. 2d is a cross-sectional view of the downhole steam generator taken along llne D-D.
Fig. 2e is a cross~sectional vlew of the downhole steam generator taken along line E-E.
5 ~ Descriptlon of the Preferred Embodiments Referrlng now to Fig. la, there is shown a partially cutaway perspective vlew of the downhole steam generator (DSG) generally designated lO. Basically, the DSG lO comprises an injec~or assembly generally deslgnated 12 coaxially connected to the top end 14 of a first cylindrical tube bundle 16 which forns the~shell of a comhust~on chamber 18. Although the precise number and size of the heat exchanger tubes is determined according to specific design require-ments, in its preferred conflguration tube bundle l6 compr~ses forty-s~x
3/16-inch holes longitudinally located within the wall portion of the ~pprox-1mately two-foot.long combust~on chanber l8. In the alternative, the tube
5 ~ bundle may comprise a plural~ty of tubes joined so as to form the cylindrical combustion chamber 18. Preferably, the first tube bundle l6 necks down from about ~ five-inch I.D. to about a 3.5-lnch I.D. at its bottom end 20 where lt is a~tached to~a second~cylindr~cal tube bundle 22 which forms the shell of the~heat~exchanger~genera~ly designated 24. In its preferred configuratlon, 0 ~ ~ heat exchanger 24 comprises~twenty-four l/2-inch O.D. tubes about 37 feet long. ~The combustion chamber 18 and heat exchanger 24 are generally designated as the heat transfer chamber which can lf desired be a one-com-; partment system. Heat exchanger 24 ends wlth a means for vent1ng combustionproducts wh~ch comprises exhaust gas turnaround 26 and Flow guide 28. The entire DSG lO is completed with steam deployment means which comprises a : .
stab-in-tube generally designated 30 d1sposed to receive the steam output of said heat exchanger 24, `t .
~l~L~75 3 ~
Ultimately, stab in-tube 30 will mate with any state-of-art well completlon packer generally deslgnated 32. Typical packers 32 are commerclally produced by varlous companles such as Baker and Brown. Fig. lb has been lncorporated so as to dep~ct the approximate propor~ons of the subject downhole steam generator~
Turning now to Figs. 2a thru 2e, there are shown long1tudinal and trans-verse cross-sectional views of the DSG 10. In operatlon, a p~lot gas is fed down pilot gas feed line 34 through a pilot gas port 36 ~nto 1niector assembly 12 where it 1s ign~ed. Although pilot gas ign~tion may be effected by ~gnition means such as electric spark, pr~mer cords, and the l~ke9 the preferred lgnition means is by combustlon wave org~nated in a combustion wave generator (not shown). The combust~on wave is then conveyed to in-jector assembly 12 by 1/4-inch combust10n wave tube 38. Once pilot ign~tion has:been e ffected, a gaseous or liquid fuel is fed down fuel llne 40 through optional filter 42 and optlonal valve 44 to the injector assembly 1~ `The fuel 1s then sprayed into ~lame holder 46 and combust~on chamber 18 by a spray nozzle 48. Concurrently w~th the ~uel flDw, an ox~d1zer such as air is pumped through a~r annulus 50 which lie between steam generator 10 and well castlng:52. :The air or other source of oxygen for combustion, also serves as prote~tive barr~er between the flame front and the interior wall of the combustlon cha~ber 18. Although ~nlt~al combust10n takes place withln the combustion:chamber, combustion also occurs along almost the entire length of the heat exchanger 24. Exhaust gas resulting from the combustion process ls driven down the entlre length of ~he heat exchanger 22 until lt encounters the low guide 28 and the exhaust gas turnaround 26. At the turnaround 26, the down flowlng exhaust gas imptnges upon the flow gulde 28 where lt is redirected to flow out of the heat exchanger 24 and up exhaust gas annulus ~6.
~ 5 3 ~
As the exhaust gas flows up annulus 56 ~t serves to add additional heat to the water/steam contalned within the second cyl1ndr~cal tube bundle 22.
When exhaust gas reaches the area of the injector assembly 21, it passes through orifice(s) 58 which provides ~he means for obtaining the deslred exhaust gas back pressure. Once throug the orifice(s) 5B, exhaust gas con-tinues to flow up annulus 56 to the well head where it ~s vented.
Concurrently with the above-described combustion process, water ls fed through a water inlet pipe 60 to manifold 62 where the flow is spl1t so as to feed the first tube bundle 16. It should be noted that tube bundle 16 may be two cylinders with an annulus, a tube-in-tube wall element, or a ; convent~onal tube bundle. Initial water heating occurs within the first tube bundle 16; however, due to the relatively short length of the combustion chamber 18, actual steam generation generally occurs within the heat ex-changer 24. Steam temperature, pressure, and quality increase until the exhaust gas turnaround 26 and flow guide 28 area is reached. At that polnt, hot exhaust gases begin their upward flow while the steam enters stab-in-tube 30 driving poppet valve 64 into the open position and injectlng steam through well complet10n packer 32 and lnto the subject oil well.
, The basic minimum objective of the present invention is to provide 1000 barrels of s~eam per day at 85X quality~ This steam is to be generated ~n;a range which varies from about 1500 psla to about 3200 psia and a well head depth which varles from about 2500 feet to about 5000 feet. Table 1 shows the bas~c energy balance ~or a system designed ~o generate steam at about 150d psia anJ at about 2500 feet.
:
~'7~3~6 g DOWNHOLE CONDITIONS
Fuel Flowrate654 lb/hr Air Flowrate10,152 lb/hr Water Flowrate14,574 lb/hr ~ : Barrels of Steam 1,000 BBl/Day : : Steam Energy15,401,520 Btu/hr Steam Quality85%
Wall Bore Heat Loss 452,989 Btu/hr ~ 10 Flue Gas Stack : Heat Loss687,346 Btu/hr Combustion Chamber ::~ Pressure 58.67 PSIA
Thus, it is apparent that there has been provided ~: 15 by the present invention a downhole steam generator capable of producing at least 1000 barrels per day of 85% quality steam at~l500 to 3200 psia and at well depths of 2500 to 5000 feet.
It is to be understood that what has been described as merely~;illustrative of the principles of the invention and that : :
20 ~ numerous arrangements~ln accordance with this invention may be devlsed:by one skilled:in the art without departing from the ::
spirit and~scope thereof.
:~
., ~ .
stab-in-tube generally designated 30 d1sposed to receive the steam output of said heat exchanger 24, `t .
~l~L~75 3 ~
Ultimately, stab in-tube 30 will mate with any state-of-art well completlon packer generally deslgnated 32. Typical packers 32 are commerclally produced by varlous companles such as Baker and Brown. Fig. lb has been lncorporated so as to dep~ct the approximate propor~ons of the subject downhole steam generator~
Turning now to Figs. 2a thru 2e, there are shown long1tudinal and trans-verse cross-sectional views of the DSG 10. In operatlon, a p~lot gas is fed down pilot gas feed line 34 through a pilot gas port 36 ~nto 1niector assembly 12 where it 1s ign~ed. Although pilot gas ign~tion may be effected by ~gnition means such as electric spark, pr~mer cords, and the l~ke9 the preferred lgnition means is by combustlon wave org~nated in a combustion wave generator (not shown). The combust~on wave is then conveyed to in-jector assembly 12 by 1/4-inch combust10n wave tube 38. Once pilot ign~tion has:been e ffected, a gaseous or liquid fuel is fed down fuel llne 40 through optional filter 42 and optlonal valve 44 to the injector assembly 1~ `The fuel 1s then sprayed into ~lame holder 46 and combust~on chamber 18 by a spray nozzle 48. Concurrently w~th the ~uel flDw, an ox~d1zer such as air is pumped through a~r annulus 50 which lie between steam generator 10 and well castlng:52. :The air or other source of oxygen for combustion, also serves as prote~tive barr~er between the flame front and the interior wall of the combustlon cha~ber 18. Although ~nlt~al combust10n takes place withln the combustion:chamber, combustion also occurs along almost the entire length of the heat exchanger 24. Exhaust gas resulting from the combustion process ls driven down the entlre length of ~he heat exchanger 22 until lt encounters the low guide 28 and the exhaust gas turnaround 26. At the turnaround 26, the down flowlng exhaust gas imptnges upon the flow gulde 28 where lt is redirected to flow out of the heat exchanger 24 and up exhaust gas annulus ~6.
~ 5 3 ~
As the exhaust gas flows up annulus 56 ~t serves to add additional heat to the water/steam contalned within the second cyl1ndr~cal tube bundle 22.
When exhaust gas reaches the area of the injector assembly 21, it passes through orifice(s) 58 which provides ~he means for obtaining the deslred exhaust gas back pressure. Once throug the orifice(s) 5B, exhaust gas con-tinues to flow up annulus 56 to the well head where it ~s vented.
Concurrently with the above-described combustion process, water ls fed through a water inlet pipe 60 to manifold 62 where the flow is spl1t so as to feed the first tube bundle 16. It should be noted that tube bundle 16 may be two cylinders with an annulus, a tube-in-tube wall element, or a ; convent~onal tube bundle. Initial water heating occurs within the first tube bundle 16; however, due to the relatively short length of the combustion chamber 18, actual steam generation generally occurs within the heat ex-changer 24. Steam temperature, pressure, and quality increase until the exhaust gas turnaround 26 and flow guide 28 area is reached. At that polnt, hot exhaust gases begin their upward flow while the steam enters stab-in-tube 30 driving poppet valve 64 into the open position and injectlng steam through well complet10n packer 32 and lnto the subject oil well.
, The basic minimum objective of the present invention is to provide 1000 barrels of s~eam per day at 85X quality~ This steam is to be generated ~n;a range which varies from about 1500 psla to about 3200 psia and a well head depth which varles from about 2500 feet to about 5000 feet. Table 1 shows the bas~c energy balance ~or a system designed ~o generate steam at about 150d psia anJ at about 2500 feet.
:
~'7~3~6 g DOWNHOLE CONDITIONS
Fuel Flowrate654 lb/hr Air Flowrate10,152 lb/hr Water Flowrate14,574 lb/hr ~ : Barrels of Steam 1,000 BBl/Day : : Steam Energy15,401,520 Btu/hr Steam Quality85%
Wall Bore Heat Loss 452,989 Btu/hr ~ 10 Flue Gas Stack : Heat Loss687,346 Btu/hr Combustion Chamber ::~ Pressure 58.67 PSIA
Thus, it is apparent that there has been provided ~: 15 by the present invention a downhole steam generator capable of producing at least 1000 barrels per day of 85% quality steam at~l500 to 3200 psia and at well depths of 2500 to 5000 feet.
It is to be understood that what has been described as merely~;illustrative of the principles of the invention and that : :
20 ~ numerous arrangements~ln accordance with this invention may be devlsed:by one skilled:in the art without departing from the ::
spirit and~scope thereof.
:~
., ~ .
Claims (13)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A downhole steam generator suitable for use in a downhole location in a well casing, comprising:
an injector assembly;
means for conveying combustion ingredients to said injector assembly;
a shell comprising hollow or tubular walls for con-veying fluid therethrough, said shell forming a combustion chamber disposed so as to receive the output of said injector assembly and a heat exchanger, disposed so as to receive the output of said combustion chamber;
means for introducing water into said hollow or tubular walls of said shell;
means for venting combustion products from said shell;
a flow guide, positioned proximate to said venting means for directing the vented combustion products up said well casing and along the exterior of said shell; and means for discharging steam generated within said hollow or tubular walls of said heat transfer chamber at said downhole location.
an injector assembly;
means for conveying combustion ingredients to said injector assembly;
a shell comprising hollow or tubular walls for con-veying fluid therethrough, said shell forming a combustion chamber disposed so as to receive the output of said injector assembly and a heat exchanger, disposed so as to receive the output of said combustion chamber;
means for introducing water into said hollow or tubular walls of said shell;
means for venting combustion products from said shell;
a flow guide, positioned proximate to said venting means for directing the vented combustion products up said well casing and along the exterior of said shell; and means for discharging steam generated within said hollow or tubular walls of said heat transfer chamber at said downhole location.
2. The downhole steam generator of Claim 1, wherein said injector assembly comprises:
a pilot gas inlet;
a pilot gas igniter adjacent to said pilot gas inlet;
a fuel injector for axially introducing a fuel into said shell; and means for introducing an oxidizer into said injec-tor assembly so as to mix with said fuel for ignition.
a pilot gas inlet;
a pilot gas igniter adjacent to said pilot gas inlet;
a fuel injector for axially introducing a fuel into said shell; and means for introducing an oxidizer into said injec-tor assembly so as to mix with said fuel for ignition.
3. The downhole steam generator of Claim 2, wherein said pilot gas igniter comprises combustion wave igniter.
4. The downhole steam generator of Claim 1, wherein said combustion chamber has a greater or equal diameter than said heat exchanger.
5. The downhole steam generator of Claim 4, wherein said combustion chamber necks down at its bottom so as to mate with said heat exchanger.
6. The downhole steam generator of Claim 1 or 5, wherein said combustion chamber is of a tube-in-tube wall construction.
7. The downhole steam generator of Claim 1 or 5, wherein said combustion chamber comprises a tube bundle.
8. The downhole steam generator of Claim 1 or 5, wherein said heat exchanger comprises a tube bundle.
9. The downhole steam generator of Claim 1, wherein said downhole steam generator further comprises means for creating backpressure in said vented combustion products.
10. The downhole steam generator of Claim 9, wherein said means for discharging steam comprises a stab-in-tube disposed so as to receive the steam output of said heat ex-changer and wherein said stab-in-tube further comprises a poppet valve biased so as to permit steam deployment and prevent an infusion of oil well residue into said downhole steam generator.
11. The downhole steam generator of Claim 5, wherein said downhole steam generator further comprises means for creating backpressure in said vented combustion products.
12. The downhole steam generator of Claim 11 wherein said means for discharging steam, comprises a stab-in-tube disposed so as to receive the steam output of said heat exchanger and wherein said stab-in-tube further comprises a poppet valve biased so as to permit steam deployment and prevent an infusion of oil well residue into said downhole steam generator.
13. The downhole steam generator of Claim 10 or 12 wherein said stab-in-tube is capable of mating with a well completion packer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US19187980A | 1980-09-29 | 1980-09-29 | |
| US191,879 | 1980-09-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1175346A true CA1175346A (en) | 1984-10-02 |
Family
ID=22707273
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376784A Expired CA1175346A (en) | 1980-09-29 | 1981-05-04 | Indirect firing downhole steam generator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1175346A (en) |
-
1981
- 1981-05-04 CA CA000376784A patent/CA1175346A/en not_active Expired
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