CA2026396C - Optimization of cyclic steam in a reservoir with inactive bottom water - Google Patents
Optimization of cyclic steam in a reservoir with inactive bottom waterInfo
- Publication number
- CA2026396C CA2026396C CA002026396A CA2026396A CA2026396C CA 2026396 C CA2026396 C CA 2026396C CA 002026396 A CA002026396 A CA 002026396A CA 2026396 A CA2026396 A CA 2026396A CA 2026396 C CA2026396 C CA 2026396C
- Authority
- CA
- Canada
- Prior art keywords
- zone
- oil
- reservoir
- steam
- well
- 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 - Fee Related
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices, or the like
- E21B33/138—Plastering the borehole wall; Injecting into the formation
Abstract
A process for preventing steam entry into a bottom water zone of a formation. Perforations are made in a well which perforations communicate with the lowest level of said bottom water zone. Air is injected into the lowest level of said zone via said well which initiates low temperature oxidizing thereby increasing the viscosity of said oil and making a heavy oil. When a desired viscosity is obtained, air injection is ceased. Said well is recompleted and perforations are placed in said well which causes it to communicate with a higher level oil saturated zone. Steam is injected into said higher level since the lowest level of the bottom water zone is closed because of the high viscosity oxidized oil. Thus, steam injection causes oil to be removed from the higher level of said formation.
Description
~2~6J~
~-5501-L
OPT~ZATqON OF CYCLIC STEAM IN A
~kKwIR WqTH INACTIVE ~OTTOM W~I~R
Related APplications m is ~r~ ~tion is related to copending application Serial No. 068,290 filed July 1, 1987. It is also related to Serial No.
292,795. Additionally, this application is related to Serial No.
292,799.
Field of the Invention mis invention relates to the use of an ~ ;7.;~y fluid to increase an oil's viscosity so that the oil can be used to prevent steam rhAnnPll;n~ into a non-aquifer bottom water zone which causes increased amounts of h~dL~dL~)~ oll~ fluids to be obtained from an adjacent h~dru~d~ ~ceous fluid bèaring zone in a formation.
Backqround of the Invention In the l~Juv~y of oil frcm oil-containing formations, it is usually p~cjhl~ to recover only minor portions of the original oil-in-place by so-called primary recovery ~lh-Y7~ which u~;l;7e only natural forces. To increa ~ the recovery of oil a variety of s~rrlC ~kiry recovery techniques are employed. These tc~hn;~lc~
include waterfloodinq, ;~o;hl~ flooding, ~hl 1 recovery, and steam flooding A problem that arises in various flooding prccP~P~ is that different strata or zones in the re ~rvoir often pos~P-~ different per~Ah;l;ties. Thus, displacing fluids enter high pPr~Ahil;ty or "thief" zones in preference to zones of lower p~rr~-h;l;ty.
Significant quantities of oil may be left in zones of lower pP --h;l;ty. To circumvent this difficulty the technique of profile control is Arr~ to plug the high pPrm~Ah;l;ty zones with polymeric ~els and thus divert the displacing fluid into the law pPr~~-h;l;ty, oil rich zones. A~mong the polyrners exarnined for improviny waterflood cvl~vLl~nce are metal cross-linked polysac- ch~rides, metal cross-linked polyacrylAm;~p~ and organic cross-linked polyacry~ ,~m; ~1PC .
Another problem that arises when steam flooding a formation having a non-aquifer bottom water zone is that on occasion stearn channels into the bottorn water zone. This bottom water zone has relatively higher mobility which allows preferential stearn entry. It is ~;ff;~llt to re-direct the steam into upper portions of the reservoir or forrnation since steam prefers the path of least resistance. ~he path of least resistance in this situation happens to be the bottom water zone. Another problem which arises is how to u ~ a polyrneric gel to close off an override area in a forrnation which has been swept by a stP~mflno~.
Polyrneric gels are disclosed in ~veral U.S. patents. Among these is U.S. Patent No. 4,157,322 which issued to Colegrove on June 5, 1979. mis gel is formed from water, a poly~rhAride polyrner, an acid y~ ~LdLing salt and a melamine resin. A poly7neric gel is ~;~clos~1 in U.S. Patent No. 4,658,898 which issued to Paul and Strom on April 21, 1987. miS patent ~;~r1~Ps an ~lP~ solution of heteropolysaccharide S-130 combined with inorganic cations which forms gels at elevated temperatures. U.S. Patent No. 4,716,966, issued to Shu on January 5, 1988, discloses a gel formed by am mo resins such as m~elamine f~r~ Phyde which modify biopolymers in combination with transitional metal ions. The ~ patents are hereby in~l~uLdLe~ by lef~L~ herein.
Basic to the problem of diverting displacing fluid with polyrneric gels is the necessity of placing the polymer where it is needed, i.e. in the high pprm~ah;l;t~ zone. This is not difficult if the gel is formed above ground. Xanthan biopolymers may be cross--linked with metal ions such as Cr+3 above ground to give gels.
These gels are shear thinning and can be injected into the formation where they then reheal. Since gel particles are being injected, they will of necessity go into high permeability zones. HGwever, man~
other gel systems are formed in-situ. One system disclosed in U.S.
Patent 3,557,562 contains acrylamide monomer, methylene-bis-acrylamide as an organic cross-linker, and a free radical initiator. m is system undergoes polymeri- zation in the formation to give a polyacrylamide cross-linked with methylene-bis-acrylamide. However, the viscosity of the soll~t-i~n when injected is like that of water. Unless mechanical isolation is used, these snll~t;nn~ are quite CApAhlP of penetrating lcw pPr~h;l;ty, oil beAring zones.
Another form of in-situ gelation involves the injeotion of polyacrylamide containing chromium in the form of chromate. A
reducing agent such as thiourea or sodium th;n~llfate is also injected to reduce the chromate in-situ to Cr~3, a species capable of cross-linking hydrolyzed polyacrylamide. Even though the polyacrylamide solution has a viscosity greater than water, it is not capable of showing the ~PlPctivity that a gel can. mus, polyacryl~m;~Pc cross linked with ~Ir~ ;l in-situ can also go into low pPr~Ah;l;ty zones. It is not useful to cross-link polyacryl; ;dP~ above ground and inject them as gels, hecall~e polyacrylamide gels undergo shear degradation.
~ herefore, what is needed is a method for preventing steam channelling in a bottom water zone where gels are not l~t; 1;7e~ which will allow steam to be re-directed into an upper zone of a reservoir so that h~dLu~cu~ aceous fluids can be removed tht~f S~
This invention is ~;rected to a method for optimizing steam injection into an oil containing reservoir which has a bottom water zone. In the practice of this method, an n~;~;7.;ng fluid is injected into the bottom water zone in an amount and for a time ~lffici~t to cause the rP~;~lAl oil to ~x;~;~e. Oxidation of the rP~;~ ~l oil causes an increase in the viscosity of the residual oil which is s1lff;ri~t to dive~t steam into an upper zone of the reservoir which contains oil. If nPr~Ary, oil with equal or smaller visc~sity than ~2~?j9~
reservoir oil is injected into the bottom water sand prior to oxidation.
Once the viscosity of the resi~1A1 oil has been oxidized to the extent desired, injection of the ~ ;ng fluid is ceased.
mereafter, steam is injected into the reservoir. This steam proceeds into the reservoir and attempts to enter the bottom water zone which contains the ~x;~;~d oil. Being unable to enter this bottom water zone, the steam is directed into an upper oil containing zone. As the steam continues to flow U r~u~l the upper oil containing zone, it carries with it oil which is produced to the surface. Thus, the thermal efficiency of a steam injection or steam stimulation method, e.g., "huff and puff" is substantially improved.
It is U1~L~rUL~ an object of this invention to close off a bottom water zone without having to ~ e gelatinous compositions.
It is another object of this invention to use ~Y;~ oil to selectively close off a bottom water zone containing r~ A1 oils therein.
It is yet another object of this invention to increa~ the thermal efficiency of a steam injection or steam stimulation method when removing oil or h~dL~cubolldceous fluids from a formation.
It is a still yet further object of this invention to u ~
aVA;l~hle materials to econr~ A1ly close off in a ~lective manner a bottom water zone.
BRIEF ~ Kl~llU~ OF THE DRAWINGS
Figure 1 is a diayL Lic plane view of a formation wherein steam is passed into a b~ttom water zone or area.
Fig~re 2 is a diayL Lic plane view showing the lower bottom water zone partially closed with low tJ', dL~re oxidized oil.
DESCRIPqION OF THE ~hk~XK~ EMBODIMENTS
During the recovery of hydrocarbonaceous fluids or oil via a cyclic steam injection ~ uc~s~, as is shcwn in FIG. 1, steam is injected into the injector well 10 and flows into the formation 16 ~ ~3 ~
via perforations 22. After entering zone 16, steam encGuntPrs resistance in zone 16 bPr~ll~e the fluid mobility therein is less than in bottom water zone 18. Steam then channels into bottom water zone 18 where the mobilitv is substantially greater than in zone 16. Cue to this, steam continually enters bottom water zone 18 without being able to contact additional hydrocarbonaceous fluids or oil in zone 16 thereabove.
A method of cyclically injecting steam is often referred to as a "push and pull" operation. ,~nm~t; - it is referred to as cyclic "steam injection" or "huff and puff" operations. In this u~e~s, steam is injected into the well to heat the formation so as to reduce the viscosity of oil therein. Afterwards, the well is shut in, and the viscous fluids along with steam are produced to the surface UILU~1 the same well.
In order to ~;r;7~ the thermal inefficiency and obtain a yL~aL~L production of h~dluudL~ol~ceous fluids or oil frcm the formation, an n~;~;7;ng fluid is injected into wellbore 10 where it enters perforations 22 as is shown in Figure 1. This n~;~;7;ng fluid can comprise air, oxygen, and mixtures thereof. ~ ;7;ng fluid continues to enter bottom water zone 18 via perforations 22 until low t ~ ~t~re oxidation has taken place to an extent desired.
The n~;~;7;~g fluid is allowed to cnnt~t any r~ oil in bottom water zone 18 in an amount and for a time sufficient to cause an increase in the viscosity of r~ l oil remaining in bottom water zone 18. After the n~;~;7;ng fluid has entered the bottom water zone 18 for a desired time, the oil therein will increase in viscosity. This increase in viscosity will be related to an increase in pressure in the ~ ;7;ng fluid which is being injected into wellbore 10. When the pressure of the oxidizing fluid has increased to the extent desired to obtain the desired viscosity increa ~, injection of the oxidizing fluid into wellbore 10 is t ;n~ted.
The ~ ;ng fluid can also have inert gases mixed with oxygen or air for cQmkustion control. When injectLng the oxidating fluid, the temperature of the for~ation should be less than about 200~F so as to avoid combustion. m e n~;~;7;ng fluid which is 2~3~
injected into the formation should contain oxygen in the amount of from about 20% to about 50%. Higher amounts of oxyyen can be use~ in the ~ ;7;ng fluid depending upon the formation temperature. In order to keep the o~;~;7;ng fluid from causing the formation to combust, an inert gas such as nitrogen or carbon ~I;o~ can be muxed with the ~ ;7;ng fluid to keep the ~u~ LdLion of the oxygen in a non-combustible state when contacting the oil in the bottom water zone.
After the ~ ;7;ng fluid has been injected into the bottom water zone 18 for a time sufficient to obtain the desired increase in viscositv of the oil, injection of ~ i7in~ fluid is ceased.
Afterwards, steam is injected into well 10 whereupon it enters zone 16 via ~LL~rd~ions 24 since the lower p~rforations and water zone 18 have been closed by the ~ ;7f~ oil. Steam is allowed to remain in the formation for a time sufficient to obtain the desired increase in the viscosity of the oil in said zone. ~his is obtained by shutting in the well for about 1 to about 12 days. Thereafter well 10 is reopened and oil and steam from formation 16 are produced to the surface via formation 24.
It is not nPc~Ary for bottom water zone 18 to be 100%
saturated with ~ater. Indeed, it is preferred to have some rP~
oil in bottom water zone 18 so as to decrease the fluid mobility therein so that a greater contrast exists between the ~ ;7~1 oil in water bottom zone 18 and the mobility of fluids contained in upper zone 16. The greater the mobility contrast between bottom water zone 18 and upper oil containing zone 16, the ~ re efficient will be the steam injection into upper zone 16. Of ccurse, a lower concentration of oil to water in bottom water zone 18 decreases the potential that the process will work as envisioned. It is pref~rred to have a 50/50 mux of oil to water in lower bottom zone 18 prior to instituting low t~Ld~re ~ i7;ng. Once lcwer bottom water zone is closed by low ~r~LdtUre 0~;~i7;r2g, the thermal efficiency of a steam injection or cyclic steam injection ~L~C~ss will be greatly increased ber~ll~e steam is no longer lost into unproductive water bottom zone 18.
Where ~fuL~ions do not exist in well 10 so as to allow m;c~tion with oil containing zone 16, the well can be ~7--2~
recc~pleted at a higher level or a horizontal or radial well can be drilled into zone 16 to the extent desired prior to initiating cyclic steam injection.
In another ~o~;r~nt where insufficient residual oil exists in bottom water zone 18, oil can be injected into well 10 so as to enter bottom water zone 18. The oil which is used can be fram any sources commonly used to obtain oil (with equal or smaller viscosity than reservoir oil). But as is preferred, oil previously produced to the surface from formation 16 can be reinjected into well 10 so as to enter bottam water zone 18. In this manner, sllff;~iPnt oil can be injected into bottom water zone 18 so as to obtain the desired saturation change in zone 18. The amount of oil injected into bottom water zone 18 as well as the amount of ~Y;~;7;ng fluid injected therein will be dependent upon conditions existing in a particular formation as those skilled in the art will readily recognize. While injecting the oxidating fluid into well 10, the process can be monitored by detecting the amount of carbon ~;~x;~P being produced from the formation by sampling gases exiting well 10 thereby avoiding combustion. An increase in the carbon ~;nY;~P cu~ .~d~ion indicates that combustion has begun in the bottam water zone instead of low t~.~k~d~re ~ ;ng of the oil in said zone. When this oocurs, it is r~r~ry to reduce the amount of oxygen being injected into formation 18 and cool down the reservoir. Alternatively, an inert gas such as nitrogen or carbon ~;~Y;~P can be injected into the formation.
Cyclic carbon ~ P steam stimulation oil recovery operations can also be commenced in zone 16 after pl~gging bottom water zone 18 by the low temperature ~Yi~;7;ng method described above. A suitable ~L'~ S is described in U.S. Patent No. 4,565,249 which issued to Pebdani et al. This patent is hereby in~u,~ bd by referen oe hereIn m lts entlrety.
2 ~
Although the present invention has be~n described with ~ef~LL~d ~ ;mPntS~ it is to be understood that rvr~if;~tions and variations may be resorted to without departing frcm the spirit and scope of this invention, as those skilled in the art will readily ~ ~L~L~. Such r-d;f;~tions and variations are considered to be within the purview and scope of the appended claims.
_g_ .~ .
~-5501-L
OPT~ZATqON OF CYCLIC STEAM IN A
~kKwIR WqTH INACTIVE ~OTTOM W~I~R
Related APplications m is ~r~ ~tion is related to copending application Serial No. 068,290 filed July 1, 1987. It is also related to Serial No.
292,795. Additionally, this application is related to Serial No.
292,799.
Field of the Invention mis invention relates to the use of an ~ ;7.;~y fluid to increase an oil's viscosity so that the oil can be used to prevent steam rhAnnPll;n~ into a non-aquifer bottom water zone which causes increased amounts of h~dL~dL~)~ oll~ fluids to be obtained from an adjacent h~dru~d~ ~ceous fluid bèaring zone in a formation.
Backqround of the Invention In the l~Juv~y of oil frcm oil-containing formations, it is usually p~cjhl~ to recover only minor portions of the original oil-in-place by so-called primary recovery ~lh-Y7~ which u~;l;7e only natural forces. To increa ~ the recovery of oil a variety of s~rrlC ~kiry recovery techniques are employed. These tc~hn;~lc~
include waterfloodinq, ;~o;hl~ flooding, ~hl 1 recovery, and steam flooding A problem that arises in various flooding prccP~P~ is that different strata or zones in the re ~rvoir often pos~P-~ different per~Ah;l;ties. Thus, displacing fluids enter high pPr~Ahil;ty or "thief" zones in preference to zones of lower p~rr~-h;l;ty.
Significant quantities of oil may be left in zones of lower pP --h;l;ty. To circumvent this difficulty the technique of profile control is Arr~ to plug the high pPrm~Ah;l;ty zones with polymeric ~els and thus divert the displacing fluid into the law pPr~~-h;l;ty, oil rich zones. A~mong the polyrners exarnined for improviny waterflood cvl~vLl~nce are metal cross-linked polysac- ch~rides, metal cross-linked polyacrylAm;~p~ and organic cross-linked polyacry~ ,~m; ~1PC .
Another problem that arises when steam flooding a formation having a non-aquifer bottom water zone is that on occasion stearn channels into the bottorn water zone. This bottom water zone has relatively higher mobility which allows preferential stearn entry. It is ~;ff;~llt to re-direct the steam into upper portions of the reservoir or forrnation since steam prefers the path of least resistance. ~he path of least resistance in this situation happens to be the bottom water zone. Another problem which arises is how to u ~ a polyrneric gel to close off an override area in a forrnation which has been swept by a stP~mflno~.
Polyrneric gels are disclosed in ~veral U.S. patents. Among these is U.S. Patent No. 4,157,322 which issued to Colegrove on June 5, 1979. mis gel is formed from water, a poly~rhAride polyrner, an acid y~ ~LdLing salt and a melamine resin. A poly7neric gel is ~;~clos~1 in U.S. Patent No. 4,658,898 which issued to Paul and Strom on April 21, 1987. miS patent ~;~r1~Ps an ~lP~ solution of heteropolysaccharide S-130 combined with inorganic cations which forms gels at elevated temperatures. U.S. Patent No. 4,716,966, issued to Shu on January 5, 1988, discloses a gel formed by am mo resins such as m~elamine f~r~ Phyde which modify biopolymers in combination with transitional metal ions. The ~ patents are hereby in~l~uLdLe~ by lef~L~ herein.
Basic to the problem of diverting displacing fluid with polyrneric gels is the necessity of placing the polymer where it is needed, i.e. in the high pprm~ah;l;t~ zone. This is not difficult if the gel is formed above ground. Xanthan biopolymers may be cross--linked with metal ions such as Cr+3 above ground to give gels.
These gels are shear thinning and can be injected into the formation where they then reheal. Since gel particles are being injected, they will of necessity go into high permeability zones. HGwever, man~
other gel systems are formed in-situ. One system disclosed in U.S.
Patent 3,557,562 contains acrylamide monomer, methylene-bis-acrylamide as an organic cross-linker, and a free radical initiator. m is system undergoes polymeri- zation in the formation to give a polyacrylamide cross-linked with methylene-bis-acrylamide. However, the viscosity of the soll~t-i~n when injected is like that of water. Unless mechanical isolation is used, these snll~t;nn~ are quite CApAhlP of penetrating lcw pPr~h;l;ty, oil beAring zones.
Another form of in-situ gelation involves the injeotion of polyacrylamide containing chromium in the form of chromate. A
reducing agent such as thiourea or sodium th;n~llfate is also injected to reduce the chromate in-situ to Cr~3, a species capable of cross-linking hydrolyzed polyacrylamide. Even though the polyacrylamide solution has a viscosity greater than water, it is not capable of showing the ~PlPctivity that a gel can. mus, polyacryl~m;~Pc cross linked with ~Ir~ ;l in-situ can also go into low pPr~Ah;l;ty zones. It is not useful to cross-link polyacryl; ;dP~ above ground and inject them as gels, hecall~e polyacrylamide gels undergo shear degradation.
~ herefore, what is needed is a method for preventing steam channelling in a bottom water zone where gels are not l~t; 1;7e~ which will allow steam to be re-directed into an upper zone of a reservoir so that h~dLu~cu~ aceous fluids can be removed tht~f S~
This invention is ~;rected to a method for optimizing steam injection into an oil containing reservoir which has a bottom water zone. In the practice of this method, an n~;~;7.;ng fluid is injected into the bottom water zone in an amount and for a time ~lffici~t to cause the rP~;~lAl oil to ~x;~;~e. Oxidation of the rP~;~ ~l oil causes an increase in the viscosity of the residual oil which is s1lff;ri~t to dive~t steam into an upper zone of the reservoir which contains oil. If nPr~Ary, oil with equal or smaller visc~sity than ~2~?j9~
reservoir oil is injected into the bottom water sand prior to oxidation.
Once the viscosity of the resi~1A1 oil has been oxidized to the extent desired, injection of the ~ ;ng fluid is ceased.
mereafter, steam is injected into the reservoir. This steam proceeds into the reservoir and attempts to enter the bottom water zone which contains the ~x;~;~d oil. Being unable to enter this bottom water zone, the steam is directed into an upper oil containing zone. As the steam continues to flow U r~u~l the upper oil containing zone, it carries with it oil which is produced to the surface. Thus, the thermal efficiency of a steam injection or steam stimulation method, e.g., "huff and puff" is substantially improved.
It is U1~L~rUL~ an object of this invention to close off a bottom water zone without having to ~ e gelatinous compositions.
It is another object of this invention to use ~Y;~ oil to selectively close off a bottom water zone containing r~ A1 oils therein.
It is yet another object of this invention to increa~ the thermal efficiency of a steam injection or steam stimulation method when removing oil or h~dL~cubolldceous fluids from a formation.
It is a still yet further object of this invention to u ~
aVA;l~hle materials to econr~ A1ly close off in a ~lective manner a bottom water zone.
BRIEF ~ Kl~llU~ OF THE DRAWINGS
Figure 1 is a diayL Lic plane view of a formation wherein steam is passed into a b~ttom water zone or area.
Fig~re 2 is a diayL Lic plane view showing the lower bottom water zone partially closed with low tJ', dL~re oxidized oil.
DESCRIPqION OF THE ~hk~XK~ EMBODIMENTS
During the recovery of hydrocarbonaceous fluids or oil via a cyclic steam injection ~ uc~s~, as is shcwn in FIG. 1, steam is injected into the injector well 10 and flows into the formation 16 ~ ~3 ~
via perforations 22. After entering zone 16, steam encGuntPrs resistance in zone 16 bPr~ll~e the fluid mobility therein is less than in bottom water zone 18. Steam then channels into bottom water zone 18 where the mobilitv is substantially greater than in zone 16. Cue to this, steam continually enters bottom water zone 18 without being able to contact additional hydrocarbonaceous fluids or oil in zone 16 thereabove.
A method of cyclically injecting steam is often referred to as a "push and pull" operation. ,~nm~t; - it is referred to as cyclic "steam injection" or "huff and puff" operations. In this u~e~s, steam is injected into the well to heat the formation so as to reduce the viscosity of oil therein. Afterwards, the well is shut in, and the viscous fluids along with steam are produced to the surface UILU~1 the same well.
In order to ~;r;7~ the thermal inefficiency and obtain a yL~aL~L production of h~dluudL~ol~ceous fluids or oil frcm the formation, an n~;~;7;ng fluid is injected into wellbore 10 where it enters perforations 22 as is shown in Figure 1. This n~;~;7;ng fluid can comprise air, oxygen, and mixtures thereof. ~ ;7;ng fluid continues to enter bottom water zone 18 via perforations 22 until low t ~ ~t~re oxidation has taken place to an extent desired.
The n~;~;7;~g fluid is allowed to cnnt~t any r~ oil in bottom water zone 18 in an amount and for a time sufficient to cause an increase in the viscosity of r~ l oil remaining in bottom water zone 18. After the n~;~;7;ng fluid has entered the bottom water zone 18 for a desired time, the oil therein will increase in viscosity. This increase in viscosity will be related to an increase in pressure in the ~ ;7;ng fluid which is being injected into wellbore 10. When the pressure of the oxidizing fluid has increased to the extent desired to obtain the desired viscosity increa ~, injection of the oxidizing fluid into wellbore 10 is t ;n~ted.
The ~ ;ng fluid can also have inert gases mixed with oxygen or air for cQmkustion control. When injectLng the oxidating fluid, the temperature of the for~ation should be less than about 200~F so as to avoid combustion. m e n~;~;7;ng fluid which is 2~3~
injected into the formation should contain oxygen in the amount of from about 20% to about 50%. Higher amounts of oxyyen can be use~ in the ~ ;7;ng fluid depending upon the formation temperature. In order to keep the o~;~;7;ng fluid from causing the formation to combust, an inert gas such as nitrogen or carbon ~I;o~ can be muxed with the ~ ;7;ng fluid to keep the ~u~ LdLion of the oxygen in a non-combustible state when contacting the oil in the bottom water zone.
After the ~ ;7;ng fluid has been injected into the bottom water zone 18 for a time sufficient to obtain the desired increase in viscositv of the oil, injection of ~ i7in~ fluid is ceased.
Afterwards, steam is injected into well 10 whereupon it enters zone 16 via ~LL~rd~ions 24 since the lower p~rforations and water zone 18 have been closed by the ~ ;7f~ oil. Steam is allowed to remain in the formation for a time sufficient to obtain the desired increase in the viscosity of the oil in said zone. ~his is obtained by shutting in the well for about 1 to about 12 days. Thereafter well 10 is reopened and oil and steam from formation 16 are produced to the surface via formation 24.
It is not nPc~Ary for bottom water zone 18 to be 100%
saturated with ~ater. Indeed, it is preferred to have some rP~
oil in bottom water zone 18 so as to decrease the fluid mobility therein so that a greater contrast exists between the ~ ;7~1 oil in water bottom zone 18 and the mobility of fluids contained in upper zone 16. The greater the mobility contrast between bottom water zone 18 and upper oil containing zone 16, the ~ re efficient will be the steam injection into upper zone 16. Of ccurse, a lower concentration of oil to water in bottom water zone 18 decreases the potential that the process will work as envisioned. It is pref~rred to have a 50/50 mux of oil to water in lower bottom zone 18 prior to instituting low t~Ld~re ~ i7;ng. Once lcwer bottom water zone is closed by low ~r~LdtUre 0~;~i7;r2g, the thermal efficiency of a steam injection or cyclic steam injection ~L~C~ss will be greatly increased ber~ll~e steam is no longer lost into unproductive water bottom zone 18.
Where ~fuL~ions do not exist in well 10 so as to allow m;c~tion with oil containing zone 16, the well can be ~7--2~
recc~pleted at a higher level or a horizontal or radial well can be drilled into zone 16 to the extent desired prior to initiating cyclic steam injection.
In another ~o~;r~nt where insufficient residual oil exists in bottom water zone 18, oil can be injected into well 10 so as to enter bottom water zone 18. The oil which is used can be fram any sources commonly used to obtain oil (with equal or smaller viscosity than reservoir oil). But as is preferred, oil previously produced to the surface from formation 16 can be reinjected into well 10 so as to enter bottam water zone 18. In this manner, sllff;~iPnt oil can be injected into bottom water zone 18 so as to obtain the desired saturation change in zone 18. The amount of oil injected into bottom water zone 18 as well as the amount of ~Y;~;7;ng fluid injected therein will be dependent upon conditions existing in a particular formation as those skilled in the art will readily recognize. While injecting the oxidating fluid into well 10, the process can be monitored by detecting the amount of carbon ~;~x;~P being produced from the formation by sampling gases exiting well 10 thereby avoiding combustion. An increase in the carbon ~;nY;~P cu~ .~d~ion indicates that combustion has begun in the bottam water zone instead of low t~.~k~d~re ~ ;ng of the oil in said zone. When this oocurs, it is r~r~ry to reduce the amount of oxygen being injected into formation 18 and cool down the reservoir. Alternatively, an inert gas such as nitrogen or carbon ~;~Y;~P can be injected into the formation.
Cyclic carbon ~ P steam stimulation oil recovery operations can also be commenced in zone 16 after pl~gging bottom water zone 18 by the low temperature ~Yi~;7;ng method described above. A suitable ~L'~ S is described in U.S. Patent No. 4,565,249 which issued to Pebdani et al. This patent is hereby in~u,~ bd by referen oe hereIn m lts entlrety.
2 ~
Although the present invention has be~n described with ~ef~LL~d ~ ;mPntS~ it is to be understood that rvr~if;~tions and variations may be resorted to without departing frcm the spirit and scope of this invention, as those skilled in the art will readily ~ ~L~L~. Such r-d;f;~tions and variations are considered to be within the purview and scope of the appended claims.
_g_ .~ .
Claims (23)
1. A method for optimizing steam injection into an oil containing reservoir having a bottom water zone comprising:
a) injecting via a well an oxidizing fluid into the bottom water zone in an amount sufficient to oxidize oil in said zone which causes said oil to increase in viscosity sufficient to divert steam into an upper zone of the reservoir and;
b) ceasing injection of said fluid and commencing thereafter steam injection into the reservoir which steam is diverted from the bottom water zone and directed into an upper oil containing zone thereby improving steam injection thermal efficiency.
a) injecting via a well an oxidizing fluid into the bottom water zone in an amount sufficient to oxidize oil in said zone which causes said oil to increase in viscosity sufficient to divert steam into an upper zone of the reservoir and;
b) ceasing injection of said fluid and commencing thereafter steam injection into the reservoir which steam is diverted from the bottom water zone and directed into an upper oil containing zone thereby improving steam injection thermal efficiency.
2. The method as recited in claim 1 where in step b) steam is injected into said reservoir by perforating the well at a higher productive zone or by drilling at least one horizontal well into the reservoir.
3. The method as recited in claim 1 where steam is injected into the reservoir by at least one well which well is thereafter shut in and oil is produced subsequently from said well.
4. The method as recited in claim 1 where in step a) oxygen is the oxidizing fluid.
5. The method as recited in claim 1 where in step a) oxygen or air mixed with an inert gas comprises the oxidizing fluid.
6. The method as recited in claim 1 where after step b) oil is produced from the reservoir.
7. A method for optimizing steam injection into a bottom water zone of a formation or reservoir from which zone oil has been removed comprising;
a) injecting oil into the bottom water zone via a well in an amount sufficient to saturate said water zone and displace water from said zone;
b) injecting via the well an oxidizing fluid into said water zone in an amount and for a time sufficient to oxidize oil in said zone which causes said oil to increase in viscosity sufficient to divert steam into an upper zone of the reservoir; and c) ceasing injection of said fluid and commencing thereafter steam injection into the reservoir which steam is diverted from the bottom water zone and directed into an upper oil containing zone thereby improving steam injection thermal efficiency.
a) injecting oil into the bottom water zone via a well in an amount sufficient to saturate said water zone and displace water from said zone;
b) injecting via the well an oxidizing fluid into said water zone in an amount and for a time sufficient to oxidize oil in said zone which causes said oil to increase in viscosity sufficient to divert steam into an upper zone of the reservoir; and c) ceasing injection of said fluid and commencing thereafter steam injection into the reservoir which steam is diverted from the bottom water zone and directed into an upper oil containing zone thereby improving steam injection thermal efficiency.
8. The method as recited in claim 7 where in step b) the oxidizing fluid is air, oxygen, and mixtures thereof.
9. The method as recited in claim 7 where in step b) steam is injected into said reservoir by perforating the well at a higher productive zone or by drilling at least one horizontal well into the reservoir.
10. The method as recited in claim 7 where steam is injected into the reservoir by at least one well which well is thereafter shut in and oil is produced subsequently from said well.
11. The method as recited in claim 7 where after step c) oil is produced from the reservoir.
12. A method for optimizing steam injection into an oil containing reservoir or formation having a bottom water zone comprising:
a) injecting via a well air into the bottom water zone in an amount sufficient to oxidize oil in said zone which causes said oil to increase in viscosity sufficient to divert steam into an upper zone of the reservoir; and b) ceasing injection of air and commencing thereafter steam injection into the reservoir which steam is diverted from the bottom water zone and directed into an upper oil containing zone thereby improving steam injection thermal efficiency.
a) injecting via a well air into the bottom water zone in an amount sufficient to oxidize oil in said zone which causes said oil to increase in viscosity sufficient to divert steam into an upper zone of the reservoir; and b) ceasing injection of air and commencing thereafter steam injection into the reservoir which steam is diverted from the bottom water zone and directed into an upper oil containing zone thereby improving steam injection thermal efficiency.
13. The method as recited in claim 12 where in step b) steam is injected into said reservoir by perforating the well at a higher productive zone or by drilling at least one horizontal well into the reservoir.
14. The method as recited in claim 12 where steam is injected into the reservoir by at least one well which well is thereafter shut in and oil is produced subsequently from said well.
15. The method as recited in claim 12 where after step b) oil is produced from the reservoir.
16. The method as recited in claim 1 where in step a) the oxidizing fluid is injected into a formation having a temperature of less than about 200°F.
17. The method as recited in claim 1 where in step a) the oxidizing fluid contains about 20 to about 50% oxygen.
18. The method as recited in claim 1 where in step a) said oxidizing fluid contains an inert gas in an amount sufficient to prevent combustion from occurring in said reservoir.
19. The method as recited in claim 1 where said bottom water zone contains a 50/50 mix of oil to water prior to instituting low temperature oxidation.
20. The method as recited in claim 7 where in step b) the oxidizing fluid is injected into a formation having a temperature of less than about 200°F.
21. The method as recited in claim 7 where in step b) the oxidizing fluid contains about 20 to about 50% oxygen.
22. The method as recited in claim 7 where in step b) said oxidizing fluid contains an inert gas in an amount sufficient to prevent combustion from occurring in said reservoir.
23. The method as recited in claim 12 where in step a) said air is injected into a formation having a temperature of less than about 200°F.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US413,809 | 1989-09-28 | ||
| US07/413,809 US4962814A (en) | 1989-09-28 | 1989-09-28 | Optimization of cyclic steam in a reservoir with inactive bottom water |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2026396A1 CA2026396A1 (en) | 1991-03-29 |
| CA2026396C true CA2026396C (en) | 1997-11-18 |
Family
ID=23638740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002026396A Expired - Fee Related CA2026396C (en) | 1989-09-28 | 1990-09-27 | Optimization of cyclic steam in a reservoir with inactive bottom water |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4962814A (en) |
| CA (1) | CA2026396C (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6446721B2 (en) | 2000-04-07 | 2002-09-10 | Chevron U.S.A. Inc. | System and method for scheduling cyclic steaming of wells |
| US7797139B2 (en) | 2001-12-07 | 2010-09-14 | Chevron U.S.A. Inc. | Optimized cycle length system and method for improving performance of oil wells |
| US7809538B2 (en) | 2006-01-13 | 2010-10-05 | Halliburton Energy Services, Inc. | Real time monitoring and control of thermal recovery operations for heavy oil reservoirs |
| US7832482B2 (en) | 2006-10-10 | 2010-11-16 | Halliburton Energy Services, Inc. | Producing resources using steam injection |
| US7770643B2 (en) | 2006-10-10 | 2010-08-10 | Halliburton Energy Services, Inc. | Hydrocarbon recovery using fluids |
| CA2972203C (en) | 2017-06-29 | 2018-07-17 | Exxonmobil Upstream Research Company | Chasing solvent for enhanced recovery processes |
| CA2974712C (en) | 2017-07-27 | 2018-09-25 | Imperial Oil Resources Limited | Enhanced methods for recovering viscous hydrocarbons from a subterranean formation as a follow-up to thermal recovery processes |
| CN107832481B (en) * | 2017-08-03 | 2021-07-06 | 中国石油化工股份有限公司 | Partitioning method for combined steam huff and puff of heavy oil reservoir |
| CA2978157C (en) | 2017-08-31 | 2018-10-16 | Exxonmobil Upstream Research Company | Thermal recovery methods for recovering viscous hydrocarbons from a subterranean formation |
| CA2983541C (en) | 2017-10-24 | 2019-01-22 | Exxonmobil Upstream Research Company | Systems and methods for dynamic liquid level monitoring and control |
| CN113494285B (en) * | 2020-03-19 | 2023-02-28 | 中国石油天然气股份有限公司 | Exploitation method for heavy oil reservoir with boundary water invading at last stage of huff and puff |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3147805A (en) * | 1962-01-19 | 1964-09-08 | Gulf Research Development Co | Method for consolidating an unconsolidated formation |
| US3324946A (en) * | 1964-11-12 | 1967-06-13 | Phillips Petroleum Co | Prevention of water invasion into a heavy crude reservoir |
| US3557562A (en) * | 1968-01-31 | 1971-01-26 | Halliburton Co | Method of forming a flexible sealant |
| US3682244A (en) * | 1971-03-05 | 1972-08-08 | Shell Oil Co | Control of a steam zone |
| US3974877A (en) * | 1974-06-26 | 1976-08-17 | Texaco Exploration Canada Ltd. | Sand control method employing low temperature oxidation |
| US3997004A (en) * | 1975-10-08 | 1976-12-14 | Texaco Inc. | Method for recovering viscous petroleum |
| US4064942A (en) * | 1976-07-21 | 1977-12-27 | Shell Canada Limited | Aquifer-plugging steam soak for layered reservoir |
| US4160481A (en) * | 1977-02-07 | 1979-07-10 | The Hop Corporation | Method for recovering subsurface earth substances |
| US4157322A (en) * | 1978-01-19 | 1979-06-05 | Merck & Co., Inc., | Water diverting gel compositions |
| US4482015A (en) * | 1983-04-14 | 1984-11-13 | Marathon Oil Company | Selectively plugging subterranean formations with a hydrocarbon soluble fluid |
| US4612990A (en) * | 1983-08-01 | 1986-09-23 | Mobil Oil Corporation | Method for diverting steam in thermal recovery process |
| US4565249A (en) * | 1983-12-14 | 1986-01-21 | Mobil Oil Corporation | Heavy oil recovery process using cyclic carbon dioxide steam stimulation |
| US4716966A (en) * | 1986-10-24 | 1988-01-05 | Mobil Oil Corporation | Amino resin modified xanthan polymer gels for permeability profile control |
| US4658898A (en) * | 1985-05-24 | 1987-04-21 | Mobil Oil Corporation | Oil reservoir permeability control using polymeric gels |
-
1989
- 1989-09-28 US US07/413,809 patent/US4962814A/en not_active Expired - Fee Related
-
1990
- 1990-09-27 CA CA002026396A patent/CA2026396C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2026396A1 (en) | 1991-03-29 |
| US4962814A (en) | 1990-10-16 |
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