CA1061713A - Recovering bitumen from subterranean formations - Google Patents
Recovering bitumen from subterranean formationsInfo
- Publication number
- CA1061713A CA1061713A CA280,172A CA280172A CA1061713A CA 1061713 A CA1061713 A CA 1061713A CA 280172 A CA280172 A CA 280172A CA 1061713 A CA1061713 A CA 1061713A
- Authority
- CA
- Canada
- Prior art keywords
- steam
- bitumen
- formation
- hydrocarbon
- production
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- 238000011084 recovery Methods 0.000 claims abstract description 13
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- 239000003208 petroleum Substances 0.000 description 17
- 239000002904 solvent Substances 0.000 description 15
- 238000010795 Steam Flooding Methods 0.000 description 5
- 239000003921 oil Substances 0.000 description 4
- 238000001256 steam distillation Methods 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
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- 230000004048 modification Effects 0.000 description 2
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- 239000011275 tar sand Substances 0.000 description 2
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Landscapes
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
RECOVERING BITUMEN FROM
SUBTERRANEAN FORMATIONS
(D#73,500-RCA-29-F) ABSTRACT
A process for enhanced recovery of bitumen from subterranean formations is disclosed, wherein steam is injected into a formation via an injection well, and a mixture of bitumen and steam condensate is produced via a production well, wherein the produced mixture is flashed for production of a steam distilled hydrocarbon fraction, and wherein the steam distilled hydrocarbon fraction is injected, with additional steam, into a subterranean formation for increased recovery of bitumen.
-I-
SUBTERRANEAN FORMATIONS
(D#73,500-RCA-29-F) ABSTRACT
A process for enhanced recovery of bitumen from subterranean formations is disclosed, wherein steam is injected into a formation via an injection well, and a mixture of bitumen and steam condensate is produced via a production well, wherein the produced mixture is flashed for production of a steam distilled hydrocarbon fraction, and wherein the steam distilled hydrocarbon fraction is injected, with additional steam, into a subterranean formation for increased recovery of bitumen.
-I-
Description
171;~
B~\CKGROUl`lD OE' T~IE INVE:Mq'IO~i The present invention relates to recovery of petroleum from subterranean formations. Particularly, it relates to recovering relatively heavy petroleum 5 oils, such as tar sands bitumen, from consolidated or unconsolidated subterranean formations employing a method wherein light hydrocarbon fractions, steam dis-tilled from produced bitumen, are reinjected with steam into the subterranean formations via injection wells, 10 and wherein produced crude, steam, and reinjected light hydrocarbons are recovered from wells producing from the same subterranean formations.
It is known, generally, to produce petroleum oils, tar sand bitumens, and related petroleum hydro-15 carbons from shale, sandstone, unconsolidated sand, and t `other subterranean formations by injecting steam into a ` first well for heating the petroleum in such formations and forcing such petroleum to a second well from which "~ such petroleum is produced. Particularly when this 20 method is employed for recovering bitumen, or heavy petroleum, from subterranean formations, a bank of oil builds up in a cold zone ahead of the advancing steam.
` This bank of restricts flow through the formation, xequiring high pressures for moving the bitumen to the 25 producing well.
An improvement of the process of recovering petroleum oils employing steam injection has been suggested in the prior art. In this improved process, a vapor mixture of superheated steam and a normally liquid 30 hydrocarbon solvent are injected, via an injection well, into a subterranean formation for forcing petroleum .. 1-- ..
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1()~1'~1;~
to a second well from which such petroleum is produced. Hydro-carbon solvents contemplated in this improved process are those which, when admixed with petroleum to be produced, will reduce the viscosity of the mixture considerably below that of the petroleum in place. Such solvents will ordinarily have the characteristics of such liquids as kerosine, gasoline, jet fuel, stoddard solvent, benzene, xylene, toluene, etc.
SUMMARY OF THE INVENTION
Now, according to the present invention, we have discovered an improved method for recovering bitumen, or heavy petroleum, from subterranean formations. In this application, "bitumen" will be understood to include heavy crude petroleum.
In accordance with the present invention there is provided, in a process for recovery of bitumen from a sub-terranean formation wherein steam is injected via an injection well into said subterranean formation, wherein bitumen is produced via a production well from said formation, wherein injection of steam into said formation is continued until a steam front reaches said production well such that steam condensate in admixture with bitumen enters the bore of said production well, the improvement which comprises:
(a) flashing said mixture of bitumen and steam condensate produced from said formation at a pressure less than the pressure of said formation for production of a vapor phase com-prising steam and steam-distilled hydrocarbon and a liquid phase comprising bitumen;
(b) injecting at least a portion of said steam-distilled hydrocarbons from step (a), with additional steam, into said formation, via said injection well, for enhancing production of bitumen from said formation via said production well.
B~\CKGROUl`lD OE' T~IE INVE:Mq'IO~i The present invention relates to recovery of petroleum from subterranean formations. Particularly, it relates to recovering relatively heavy petroleum 5 oils, such as tar sands bitumen, from consolidated or unconsolidated subterranean formations employing a method wherein light hydrocarbon fractions, steam dis-tilled from produced bitumen, are reinjected with steam into the subterranean formations via injection wells, 10 and wherein produced crude, steam, and reinjected light hydrocarbons are recovered from wells producing from the same subterranean formations.
It is known, generally, to produce petroleum oils, tar sand bitumens, and related petroleum hydro-15 carbons from shale, sandstone, unconsolidated sand, and t `other subterranean formations by injecting steam into a ` first well for heating the petroleum in such formations and forcing such petroleum to a second well from which "~ such petroleum is produced. Particularly when this 20 method is employed for recovering bitumen, or heavy petroleum, from subterranean formations, a bank of oil builds up in a cold zone ahead of the advancing steam.
` This bank of restricts flow through the formation, xequiring high pressures for moving the bitumen to the 25 producing well.
An improvement of the process of recovering petroleum oils employing steam injection has been suggested in the prior art. In this improved process, a vapor mixture of superheated steam and a normally liquid 30 hydrocarbon solvent are injected, via an injection well, into a subterranean formation for forcing petroleum .. 1-- ..
. . :.
1()~1'~1;~
to a second well from which such petroleum is produced. Hydro-carbon solvents contemplated in this improved process are those which, when admixed with petroleum to be produced, will reduce the viscosity of the mixture considerably below that of the petroleum in place. Such solvents will ordinarily have the characteristics of such liquids as kerosine, gasoline, jet fuel, stoddard solvent, benzene, xylene, toluene, etc.
SUMMARY OF THE INVENTION
Now, according to the present invention, we have discovered an improved method for recovering bitumen, or heavy petroleum, from subterranean formations. In this application, "bitumen" will be understood to include heavy crude petroleum.
In accordance with the present invention there is provided, in a process for recovery of bitumen from a sub-terranean formation wherein steam is injected via an injection well into said subterranean formation, wherein bitumen is produced via a production well from said formation, wherein injection of steam into said formation is continued until a steam front reaches said production well such that steam condensate in admixture with bitumen enters the bore of said production well, the improvement which comprises:
(a) flashing said mixture of bitumen and steam condensate produced from said formation at a pressure less than the pressure of said formation for production of a vapor phase com-prising steam and steam-distilled hydrocarbon and a liquid phase comprising bitumen;
(b) injecting at least a portion of said steam-distilled hydrocarbons from step (a), with additional steam, into said formation, via said injection well, for enhancing production of bitumen from said formation via said production well.
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i~l'71~
In another aspect the present invention provides a process for recovering bitumen from a subterranean formation, which process comprising:
(a) injecting steam into said formation via an injection well;
(b) producing bitumen from said formation via a production well, (c) continuing injection of said steam and production of said bitumen until communication between said injection well and said production well is established through said formation such that a mixture of bitumen and steam condensate enters the bore of said production well;
(d) flashing said mixture of bitumen and steam condensate : :
for production of a vapor phase comprising steam and steam-distilled hydrocarbon, and production of a liquid phase compris- ~:
ing bitumen; :
: (e) condensing, in a condensing zone, said vapor phase for :.:
production of a condensate comprising water and condensed hydro-carbon;
(f) injecting said condensed hydrocarbon with additional steam into said formation, via said injection well, for enhancing recovery of additional bitumen from said formation.
In a preferred embodiment of such a process the liquid volume ratio of injected condensed hydrocarbon to additional steam is in the range of about 1:1 to about 1:100, and the volume of injected condensed hydrocarbon is equivalent to about ~ 1-100 percent of the pore volume of that portion of the forma-`~ tion swept by the injected hydrocarbon and additional steam.
In one embodiment of the present invention, the improved process comprises:
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. - 2 a) -~ .
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a) injecting steam into a bitumen containing subterranean formation via at least one in-jection well;
b) producing bitumen from said bitumen containing subterranean formation via at least one production well;
c) continuing said steam injection and said bitumen production for a time sufficient to establish communication between said injec-tion well and said production well such that a mixture of bitumen and steam condensate enters said production well;
.~` '' ' .
.
- 2(b) -.
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1()6171~
7 d) flashinc~, in a fl~s~l æone, s~id ~i~ture of bitumcn and steam condcnsate for production of a liquid phase comprising bitumen and a vapor phase comprisiny steam and hydrocarbon vapor;
e) condensing, in a condenser, said vapor phase for producing a condensate comprising water and liquid hydrocarbon;
f) separating, in a gravity separation zone, ~ said condensate into a water phase and a hydrocarbon phase;
g) injecting said hydrocarbon phase, with additional steam, into said injection well for displacing additional bitumen from the formation.
k In one alternative, the total condensate of step (e) comprising water and steam distilled hydrocarbon may be reinjected with additional steam into the sub-terranean formation. In this alternative, the condensing step (d) may be dispensed with, ana the flashed vapor mixed directly with the steam, by means such as a jet pump.
Under certain conditions, when the produced fluid is sufficiently hot, flashing of water and steam ~5 distilled hydrocarbons can occur in the well bore of the producing well. In such situations, vapor from the producing well head may be xecovered directly for o~tain--ing steam distillea hydrocarbons suitable for reinjection into the subterranean formation.
i~l'71~
In another aspect the present invention provides a process for recovering bitumen from a subterranean formation, which process comprising:
(a) injecting steam into said formation via an injection well;
(b) producing bitumen from said formation via a production well, (c) continuing injection of said steam and production of said bitumen until communication between said injection well and said production well is established through said formation such that a mixture of bitumen and steam condensate enters the bore of said production well;
(d) flashing said mixture of bitumen and steam condensate : :
for production of a vapor phase comprising steam and steam-distilled hydrocarbon, and production of a liquid phase compris- ~:
ing bitumen; :
: (e) condensing, in a condensing zone, said vapor phase for :.:
production of a condensate comprising water and condensed hydro-carbon;
(f) injecting said condensed hydrocarbon with additional steam into said formation, via said injection well, for enhancing recovery of additional bitumen from said formation.
In a preferred embodiment of such a process the liquid volume ratio of injected condensed hydrocarbon to additional steam is in the range of about 1:1 to about 1:100, and the volume of injected condensed hydrocarbon is equivalent to about ~ 1-100 percent of the pore volume of that portion of the forma-`~ tion swept by the injected hydrocarbon and additional steam.
In one embodiment of the present invention, the improved process comprises:
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.
. - 2 a) -~ .
~
.
.
:
1~17~
a) injecting steam into a bitumen containing subterranean formation via at least one in-jection well;
b) producing bitumen from said bitumen containing subterranean formation via at least one production well;
c) continuing said steam injection and said bitumen production for a time sufficient to establish communication between said injec-tion well and said production well such that a mixture of bitumen and steam condensate enters said production well;
.~` '' ' .
.
- 2(b) -.
,`t"
1()6171~
7 d) flashinc~, in a fl~s~l æone, s~id ~i~ture of bitumcn and steam condcnsate for production of a liquid phase comprising bitumen and a vapor phase comprisiny steam and hydrocarbon vapor;
e) condensing, in a condenser, said vapor phase for producing a condensate comprising water and liquid hydrocarbon;
f) separating, in a gravity separation zone, ~ said condensate into a water phase and a hydrocarbon phase;
g) injecting said hydrocarbon phase, with additional steam, into said injection well for displacing additional bitumen from the formation.
k In one alternative, the total condensate of step (e) comprising water and steam distilled hydrocarbon may be reinjected with additional steam into the sub-terranean formation. In this alternative, the condensing step (d) may be dispensed with, ana the flashed vapor mixed directly with the steam, by means such as a jet pump.
Under certain conditions, when the produced fluid is sufficiently hot, flashing of water and steam ~5 distilled hydrocarbons can occur in the well bore of the producing well. In such situations, vapor from the producing well head may be xecovered directly for o~tain--ing steam distillea hydrocarbons suitable for reinjection into the subterranean formation.
-3-.. '~ , '.
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~()ti1~71;~
1 For situations ~7here~ the produc~d Jni~tUre of bitumen and steam cond~nsate i~ no~ sufficiently hot for flashin~ of a vapor comprising stearn distilled hydro-carbon and steam, additional heat may be added to the produced liquid prior to flashing. Such heat may be added by indirect heat exchange means. Preferably, how-ever, steam is added directly to the produced bitumen in a flash ~one for increasing the amount of steam dis-tilled hydrocarbons produced.
Advantages of the process of the present invention over processes of the prior art include: in-creased displacement of bitumen from a subterranean formation employing an injected mixture of steam and the light hydrocarbon steam distilled from the produced bitumen, as compared to bitumen displacement obtained `~ using steam-hydrocarbon mixtures of the prior art.
Also, the steam-distilled hydrocarbon for injection with steam to enhance production of bitumen is obtained at ` the production site, and expensive hydrocarbon solvents ~xom external sources are not required. These, and other advantages of the process of the present invention ` will be discussed in the detailea description of the `~ invention which follows.
DETA TED DESCRIPTION OF T~E INVENTION
~ 25 When steam flooding a bitumen bearing reservoir, `~ such as a subterranean tar sand formation, a steam front comprising a bank of condensed hot water is often propagated from the injection well towards the producing well. As the steam front propagates, steam distillation takes 30 place in the steam zone behind the steam front, evaporating -~
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- - , . .. . . .
~()ti1~71;~
1 For situations ~7here~ the produc~d Jni~tUre of bitumen and steam cond~nsate i~ no~ sufficiently hot for flashin~ of a vapor comprising stearn distilled hydro-carbon and steam, additional heat may be added to the produced liquid prior to flashing. Such heat may be added by indirect heat exchange means. Preferably, how-ever, steam is added directly to the produced bitumen in a flash ~one for increasing the amount of steam dis-tilled hydrocarbons produced.
Advantages of the process of the present invention over processes of the prior art include: in-creased displacement of bitumen from a subterranean formation employing an injected mixture of steam and the light hydrocarbon steam distilled from the produced bitumen, as compared to bitumen displacement obtained `~ using steam-hydrocarbon mixtures of the prior art.
Also, the steam-distilled hydrocarbon for injection with steam to enhance production of bitumen is obtained at ` the production site, and expensive hydrocarbon solvents ~xom external sources are not required. These, and other advantages of the process of the present invention ` will be discussed in the detailea description of the `~ invention which follows.
DETA TED DESCRIPTION OF T~E INVENTION
~ 25 When steam flooding a bitumen bearing reservoir, `~ such as a subterranean tar sand formation, a steam front comprising a bank of condensed hot water is often propagated from the injection well towards the producing well. As the steam front propagates, steam distillation takes 30 place in the steam zone behind the steam front, evaporating -~
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1 h~drocarbon fractions of the bitumen . Continuous st~arn distillation behind the steam front cnriches the hydro-carbon content in the steam phase. Cont~mporaneously, due to the condensation of the hydrocarbon vapors ahead of the steam front, a region of solvent bank will be established. When the steam front reaches the producing well, the light hydrocarbons in the solvent bank will be produced to the surface together with the displaced bitumen. At the producing wellbore, the steam distillation efficiency may be further increased due to reduced pressure ~compared to formation pressure) within the wellbore~ Such pressure reduction will induce steam distillation conditions and hydrocarbons of lower density than the bitumen will be evaporated with steam. Conse- -15 quently, a large amount of light hydrocarbons may be produced with the produced steam.
We have discovered that this Pteam distilled-hydrocarbon fraction of the produced bitumen has superior .
solvent properties for enhancing production of additional bitumen when such light hydrocarbon is reinjected with additional steam into a subterranean formation. This " discovery forms the basis of our invention. ~ ;
`~ Hydrocarbon bearing formations for which the process of the present invention is useful include those 2~ which may be produced emplbying steam flooding techniques. -` For example, the present invention may be appllea to ormations which are depressured or underpressured and which contain heavy (low API gravity) petroleum deposits or bitumen. Particularly, the pxocess o the present _5_ .. .
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:
.:..
: -~Ui1 71~3 . , invention is applicable to formations near the earth's surface, such as tar sands which will not contain high pressures.
The temperature of the steam and steam dis-tilled hydrocarbon injected into a subterranean forma-tion for enhancing recovery of bitumen, is selected to carry sufficient heat into the formation to produce an advancing steam front with the associated hydrocarbon bank. The temperature of the injected mixture will be sufficient to maintain a steam phase at formation pressures, and usually will be sufficient to provide some superheat at injection pressures. For example, temperatures of about 225F may be used for formations at about atmospheric pressure, and temperatures in the 15 range of 470-600F may be used in formations with pressures of about 500 psig. Such temperatures of injected steam and light hydrocarbon may be adjusted for the injection pressure of a particular subterranean formation from which bitumen is to be produced.
The proportion of steam distilled hydrocarbon `` to steam in the injected mixture may vary over a relatively large range of liquid volume ratios of about 1:1 to ~ about 1:100 steam-distilled hydrocarbon to steam `
`; respectively.
When steam-distilled hydrocarbon comprises a large proportion of the injected vapor, the solvent power for reducing viscosity of bitumen in the formation is increased such that the bitumen will flow more readily toward the production well. However, the amount of heat per volume of injected vapor is decreased. When .
... ..
'71;~
1 steam-distilled hydrocarbo~ ompri.SC5 a very sma'l pLOpOrtion of the injected vapors, its solvent po~/er is substantially curtailed. Consecluently, liquid volume ratios of steam-distilled hydrocarbon to steam in the injected vapor in the range of about 1:10 to about 1:50 respectively are preferred for providing a good balance of heat input and amount of solvent per volume of injected vapor for enhancing production of bitumen from the formation.
In the process of the present invention, the steam-distilled hydrocarbon may be injected along with steam at commencement of a steam flood; may be injected after the steam front has reached the production well;
or may be injected when the steam front is in an inter-1~ mediate position between the injection well and the production well.
When the steam-distilled hydrocarbon is injected a commencement of steam flooding, a solvent bank will accumulate rapidly, improving the recovery of bitumen.
However, the accumulated solvent bank may increase ` pressure drop through the formation, thus requiring increased injection pressure to drive the bitumen to the production well. ~ -When the steam-distilled hydrocarbon is in-jected after the steam front has reached the production ~ell, the formation temperature will be increased. - ~-Thus, solution of hydrocarbon with remaining bitumen will be increased and the viscosity of the resulting solution will be decreased.
Recovery of a steam distilled hydrocarbon fraction, having superior properties over other hydro-carbon fractions for recovery of additional bitumen or _7_ ' ' . .
heavy petroleum, may be obtained directly from the production wellbore in the case where the steam front has reached the production well or may be recovered from produced bitumen by steam distillation techniques. In either case, the steam distilled hydrocarbon fraction exhibits improved solvent ability for production of additional bitumen, and is advantageously produced at the production site, such that expensive solvents need not be imported.
The discussion thus far has been in terms of reinjecting the steam distilled hydrocarbon fraction into an injection well associated with a production well from which the hydrocarbon fraction is obtained. It is ~ to be understood that all or a part of such steam dis-`~ 15 tilled hydrocarbon fraction may also be injected into another injection well for the same benefits of enhanced production of bitumen. Also, within contemplation of the present invention is the situation where one injection -~` well serves two or more production wells.
The total volume of steam-distilled hydro-carbon injected into a subterranean formation according ; . .
to the method of the present invention is sufficient to result in increased production of bitumen from the formation, and will be proportional to the pore volume (volume pores/volume of formation) and the total volume of the formation swept by the injected hydrocarbon-steam `
mixture flowing to the production well. For practical ~ increased recoveries, the total injected volume of light `~ hydrocarbon should be in the range of 1-100 percent of ~
30 the total pore volume in that portion of a formation -1(3~1'~1;~
I st~eL~t by the hy~ro-~lrborl ste~m-lnixtur~. Pre~era~1~, the total amoun-t of steam-distilled hydrocarbon injected ~ill be in the ran~e of about 5-20 percent of the total pore volume in that portion of a formation swept ~y the hydrocarbon-steam mixture. Should the total volume of injected hydrocarbon be less than 1 percent of the total swept pore volume, no substantial increase in production will occur over that obtained by steam flooding alone.
Use of a total volume of injected hydrocarbon exceeding 100 percent of the total swept pore volume will not be economically justified by increased production of bitumen.
` One embodiment of the improved bitumen recovery process of the present invention is applied as described 1~ below. Steam is injected into a bitumen containing tar sands formation via an injection well for a time sufficient ~; for a steam front and an associated ban~ of bitumen to reach a production well. A hot mixture of bitumen and - -steam condensate enters the production wellbore rising toward the well head at the earth's surface. As the hot -~
mixture xises in the production wellbore, pressure decreases allowing a portion of the steam condensate to flash into steam, thereby steam distilling a hydrocarbon vapor fraction from the bitumen. At the production well heàd, vapor from the wellbore is separated from produced liguid, and the vapor is condensed in a condenser.
Condensate from the condenser flows into a receiver ~, vessel wherein the condensate separates under the in~
fluence of gravity into a hydrocarbon phase and water phase. Hydrocarbon phase from the receiver is injected ~, , -- .
w:ith additional steam into the :injection well for pro-duction of additional bitumen from the suhterranean formation.
It is to be understood that modifications and variations of the process described in the foregoing specification will occur to those skilled in the art, which modifications and variations are within the spirit and scope of the present invention. Consequently, the only limitations of the present invention intended are those included in the appended claims.
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1 h~drocarbon fractions of the bitumen . Continuous st~arn distillation behind the steam front cnriches the hydro-carbon content in the steam phase. Cont~mporaneously, due to the condensation of the hydrocarbon vapors ahead of the steam front, a region of solvent bank will be established. When the steam front reaches the producing well, the light hydrocarbons in the solvent bank will be produced to the surface together with the displaced bitumen. At the producing wellbore, the steam distillation efficiency may be further increased due to reduced pressure ~compared to formation pressure) within the wellbore~ Such pressure reduction will induce steam distillation conditions and hydrocarbons of lower density than the bitumen will be evaporated with steam. Conse- -15 quently, a large amount of light hydrocarbons may be produced with the produced steam.
We have discovered that this Pteam distilled-hydrocarbon fraction of the produced bitumen has superior .
solvent properties for enhancing production of additional bitumen when such light hydrocarbon is reinjected with additional steam into a subterranean formation. This " discovery forms the basis of our invention. ~ ;
`~ Hydrocarbon bearing formations for which the process of the present invention is useful include those 2~ which may be produced emplbying steam flooding techniques. -` For example, the present invention may be appllea to ormations which are depressured or underpressured and which contain heavy (low API gravity) petroleum deposits or bitumen. Particularly, the pxocess o the present _5_ .. .
' ~ .
:
.:..
: -~Ui1 71~3 . , invention is applicable to formations near the earth's surface, such as tar sands which will not contain high pressures.
The temperature of the steam and steam dis-tilled hydrocarbon injected into a subterranean forma-tion for enhancing recovery of bitumen, is selected to carry sufficient heat into the formation to produce an advancing steam front with the associated hydrocarbon bank. The temperature of the injected mixture will be sufficient to maintain a steam phase at formation pressures, and usually will be sufficient to provide some superheat at injection pressures. For example, temperatures of about 225F may be used for formations at about atmospheric pressure, and temperatures in the 15 range of 470-600F may be used in formations with pressures of about 500 psig. Such temperatures of injected steam and light hydrocarbon may be adjusted for the injection pressure of a particular subterranean formation from which bitumen is to be produced.
The proportion of steam distilled hydrocarbon `` to steam in the injected mixture may vary over a relatively large range of liquid volume ratios of about 1:1 to ~ about 1:100 steam-distilled hydrocarbon to steam `
`; respectively.
When steam-distilled hydrocarbon comprises a large proportion of the injected vapor, the solvent power for reducing viscosity of bitumen in the formation is increased such that the bitumen will flow more readily toward the production well. However, the amount of heat per volume of injected vapor is decreased. When .
... ..
'71;~
1 steam-distilled hydrocarbo~ ompri.SC5 a very sma'l pLOpOrtion of the injected vapors, its solvent po~/er is substantially curtailed. Consecluently, liquid volume ratios of steam-distilled hydrocarbon to steam in the injected vapor in the range of about 1:10 to about 1:50 respectively are preferred for providing a good balance of heat input and amount of solvent per volume of injected vapor for enhancing production of bitumen from the formation.
In the process of the present invention, the steam-distilled hydrocarbon may be injected along with steam at commencement of a steam flood; may be injected after the steam front has reached the production well;
or may be injected when the steam front is in an inter-1~ mediate position between the injection well and the production well.
When the steam-distilled hydrocarbon is injected a commencement of steam flooding, a solvent bank will accumulate rapidly, improving the recovery of bitumen.
However, the accumulated solvent bank may increase ` pressure drop through the formation, thus requiring increased injection pressure to drive the bitumen to the production well. ~ -When the steam-distilled hydrocarbon is in-jected after the steam front has reached the production ~ell, the formation temperature will be increased. - ~-Thus, solution of hydrocarbon with remaining bitumen will be increased and the viscosity of the resulting solution will be decreased.
Recovery of a steam distilled hydrocarbon fraction, having superior properties over other hydro-carbon fractions for recovery of additional bitumen or _7_ ' ' . .
heavy petroleum, may be obtained directly from the production wellbore in the case where the steam front has reached the production well or may be recovered from produced bitumen by steam distillation techniques. In either case, the steam distilled hydrocarbon fraction exhibits improved solvent ability for production of additional bitumen, and is advantageously produced at the production site, such that expensive solvents need not be imported.
The discussion thus far has been in terms of reinjecting the steam distilled hydrocarbon fraction into an injection well associated with a production well from which the hydrocarbon fraction is obtained. It is ~ to be understood that all or a part of such steam dis-`~ 15 tilled hydrocarbon fraction may also be injected into another injection well for the same benefits of enhanced production of bitumen. Also, within contemplation of the present invention is the situation where one injection -~` well serves two or more production wells.
The total volume of steam-distilled hydro-carbon injected into a subterranean formation according ; . .
to the method of the present invention is sufficient to result in increased production of bitumen from the formation, and will be proportional to the pore volume (volume pores/volume of formation) and the total volume of the formation swept by the injected hydrocarbon-steam `
mixture flowing to the production well. For practical ~ increased recoveries, the total injected volume of light `~ hydrocarbon should be in the range of 1-100 percent of ~
30 the total pore volume in that portion of a formation -1(3~1'~1;~
I st~eL~t by the hy~ro-~lrborl ste~m-lnixtur~. Pre~era~1~, the total amoun-t of steam-distilled hydrocarbon injected ~ill be in the ran~e of about 5-20 percent of the total pore volume in that portion of a formation swept ~y the hydrocarbon-steam mixture. Should the total volume of injected hydrocarbon be less than 1 percent of the total swept pore volume, no substantial increase in production will occur over that obtained by steam flooding alone.
Use of a total volume of injected hydrocarbon exceeding 100 percent of the total swept pore volume will not be economically justified by increased production of bitumen.
` One embodiment of the improved bitumen recovery process of the present invention is applied as described 1~ below. Steam is injected into a bitumen containing tar sands formation via an injection well for a time sufficient ~; for a steam front and an associated ban~ of bitumen to reach a production well. A hot mixture of bitumen and - -steam condensate enters the production wellbore rising toward the well head at the earth's surface. As the hot -~
mixture xises in the production wellbore, pressure decreases allowing a portion of the steam condensate to flash into steam, thereby steam distilling a hydrocarbon vapor fraction from the bitumen. At the production well heàd, vapor from the wellbore is separated from produced liguid, and the vapor is condensed in a condenser.
Condensate from the condenser flows into a receiver ~, vessel wherein the condensate separates under the in~
fluence of gravity into a hydrocarbon phase and water phase. Hydrocarbon phase from the receiver is injected ~, , -- .
w:ith additional steam into the :injection well for pro-duction of additional bitumen from the suhterranean formation.
It is to be understood that modifications and variations of the process described in the foregoing specification will occur to those skilled in the art, which modifications and variations are within the spirit and scope of the present invention. Consequently, the only limitations of the present invention intended are those included in the appended claims.
' ~;
.
Claims (8)
1. In a process for recovery of bitumen from a subterranean formation wherein steam is injected via an injection well into said subterranean formation, wherein bitumen is produced via a production well from said formation, wherein injection of steam into said formation is continued until a steam front reaches said production well such that steam condensate in admixture with bitumen enters the bore of said production well, the improvement which comprises:
a) flashing said mixture of bitumen and steam condensate produced from said formation at a pressure less than the pressure of said formation for production of a vapor phase comprising steam and steam-distilled hydrocarbon and a liquid phase comprising bitumen;
b) injecting at least a portion of said steam-distilled hydrocarbons from step (a), with addi-tional steam, into said formation, via said injection well, for enhancing production of bitumen from said formation via said production well.
a) flashing said mixture of bitumen and steam condensate produced from said formation at a pressure less than the pressure of said formation for production of a vapor phase comprising steam and steam-distilled hydrocarbon and a liquid phase comprising bitumen;
b) injecting at least a portion of said steam-distilled hydrocarbons from step (a), with addi-tional steam, into said formation, via said injection well, for enhancing production of bitumen from said formation via said production well.
2. The process of Claim 1 wherein the amount of steam-distilled hydrocarbon injected into said formation is equivalent to about 1-100 percent of the total pore volume of that portion of the formation through which the steam and steam-distilled hydrocarbon flow to said production well.
3 . The process of Claim 2 where; n the steam-distilled hydrocarbon and additional steam in-jected into said formation are at an injection pressure sufficient to force a flow of steam, hydrocarbon and bitumen toward said production well, and are at a temperature sufficient to maintain the additional steam completely in the vapor phase at said injection pressure.
4. The process of Claim 3 wherein said vapor phase of step (a) is condensed, in a condensing zone, for production of a water phase and a liquid hydrocarbon phase; wherein at least a portion of said liquid hydro-carbon phase is injected, as steam-distilled hydrocarbon in step (b) into said formation.
5. The process of Claim 4 wherein said liquid hydrocarbon phase is separated from said water phase prior to injection, in step (b) into said forma-tion.
6. The process of Claim 5 wherein flashing of said mixture of steam condensate and bitumen occurs in said production wellbore and wherein said vapor phase comprising steam and steam-distilled hydrocarbon is separated from said liquid phase comprising bitumen at the head of said production well.
7. A process for recovering bitumen from a subterranean formation, which process comprising:
a) injecting steam into said formation via an injection well;
b) producing bitumen from said formation via a production well;
c) continuing injection of said steam and production of said bitumen until communication between said injection well and said production well is esta-blished through said formation such that a mixture of bitumen and steam condensate enters the bore of said production well;
d) flashing said mixture of bitumen and steam condensate for production of a vapor phase comprising steam and steam-distilled hydrocarbon, and production of a liquid phase comprising bitumen;
e) condensing, in a condensing zone, said vapor phase for production of a condensate comprising water and condensed hydrocarbon;
f) injecting said condensed hydrocarbon with additional steam into said formation, via said injection well, for enhancing recovery of additional bitumen from said formation.
a) injecting steam into said formation via an injection well;
b) producing bitumen from said formation via a production well;
c) continuing injection of said steam and production of said bitumen until communication between said injection well and said production well is esta-blished through said formation such that a mixture of bitumen and steam condensate enters the bore of said production well;
d) flashing said mixture of bitumen and steam condensate for production of a vapor phase comprising steam and steam-distilled hydrocarbon, and production of a liquid phase comprising bitumen;
e) condensing, in a condensing zone, said vapor phase for production of a condensate comprising water and condensed hydrocarbon;
f) injecting said condensed hydrocarbon with additional steam into said formation, via said injection well, for enhancing recovery of additional bitumen from said formation.
8. The process of Claim 7 wherein the liquid volume ratio of injected condensed hydrocarbon to additional steam is in the range of about 1:1 to about 1:100, and wherein the volume of injected condensed hydrocarbon is equivalent to about 1-100 percent of the pore volume of that portion of the formation swept by the injected hydrocarbon and additional steam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA280,172A CA1061713A (en) | 1977-06-09 | 1977-06-09 | Recovering bitumen from subterranean formations |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA280,172A CA1061713A (en) | 1977-06-09 | 1977-06-09 | Recovering bitumen from subterranean formations |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061713A true CA1061713A (en) | 1979-09-04 |
Family
ID=4108851
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA280,172A Expired CA1061713A (en) | 1977-06-09 | 1977-06-09 | Recovering bitumen from subterranean formations |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1061713A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4687058A (en) * | 1986-05-22 | 1987-08-18 | Conoco Inc. | Solvent enhanced fracture-assisted steamflood process |
| US4697642A (en) * | 1986-06-27 | 1987-10-06 | Tenneco Oil Company | Gravity stabilized thermal miscible displacement process |
| WO2015143034A1 (en) * | 2014-03-21 | 2015-09-24 | Dow Global Technologies Llc | Staged steam extraction of in situ bitumen |
| US10487636B2 (en) | 2017-07-27 | 2019-11-26 | Exxonmobil Upstream Research Company | Enhanced methods for recovering viscous hydrocarbons from a subterranean formation as a follow-up to thermal recovery processes |
| US11002123B2 (en) | 2017-08-31 | 2021-05-11 | Exxonmobil Upstream Research Company | Thermal recovery methods for recovering viscous hydrocarbons from a subterranean formation |
| US11142681B2 (en) | 2017-06-29 | 2021-10-12 | Exxonmobil Upstream Research Company | Chasing solvent for enhanced recovery processes |
| US11261725B2 (en) | 2017-10-24 | 2022-03-01 | Exxonmobil Upstream Research Company | Systems and methods for estimating and controlling liquid level using periodic shut-ins |
-
1977
- 1977-06-09 CA CA280,172A patent/CA1061713A/en not_active Expired
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4687058A (en) * | 1986-05-22 | 1987-08-18 | Conoco Inc. | Solvent enhanced fracture-assisted steamflood process |
| US4697642A (en) * | 1986-06-27 | 1987-10-06 | Tenneco Oil Company | Gravity stabilized thermal miscible displacement process |
| WO2015143034A1 (en) * | 2014-03-21 | 2015-09-24 | Dow Global Technologies Llc | Staged steam extraction of in situ bitumen |
| CN106164412A (en) * | 2014-03-21 | 2016-11-23 | 陶氏环球技术有限责任公司 | The classification steam extraction of Colophonium in situ |
| AU2015231341B2 (en) * | 2014-03-21 | 2019-01-17 | Dow Global Technologies Llc | Staged steam extraction of in situ bitumen |
| US10400564B2 (en) | 2014-03-21 | 2019-09-03 | Dow Global Technologies Llc | Staged steam extraction of in situ bitumen |
| RU2703059C2 (en) * | 2014-03-21 | 2019-10-15 | ДАУ ГЛОБАЛ ТЕКНОЛОДЖИЗ ЭлЭлСи | In-situ multi-step steam extraction of bitumen |
| US11142681B2 (en) | 2017-06-29 | 2021-10-12 | Exxonmobil Upstream Research Company | Chasing solvent for enhanced recovery processes |
| US10487636B2 (en) | 2017-07-27 | 2019-11-26 | Exxonmobil Upstream Research Company | Enhanced methods for recovering viscous hydrocarbons from a subterranean formation as a follow-up to thermal recovery processes |
| US11002123B2 (en) | 2017-08-31 | 2021-05-11 | Exxonmobil Upstream Research Company | Thermal recovery methods for recovering viscous hydrocarbons from a subterranean formation |
| US11261725B2 (en) | 2017-10-24 | 2022-03-01 | Exxonmobil Upstream Research Company | Systems and methods for estimating and controlling liquid level using periodic shut-ins |
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