CA2069735A1 - Process for in-situ enrichment of gas used in miscible flooding - Google Patents
Process for in-situ enrichment of gas used in miscible floodingInfo
- Publication number
- CA2069735A1 CA2069735A1 CA002069735A CA2069735A CA2069735A1 CA 2069735 A1 CA2069735 A1 CA 2069735A1 CA 002069735 A CA002069735 A CA 002069735A CA 2069735 A CA2069735 A CA 2069735A CA 2069735 A1 CA2069735 A1 CA 2069735A1
- Authority
- CA
- Canada
- Prior art keywords
- gas
- formation
- hydrocarbons
- enriched
- carbon dioxide
- 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.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000011065 in-situ storage Methods 0.000 title abstract description 4
- 239000007789 gas Substances 0.000 claims abstract description 118
- 150000002430 hydrocarbons Chemical group 0.000 claims abstract description 77
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 70
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 63
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 51
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 27
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 20
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000003345 natural gas Substances 0.000 claims abstract description 14
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 13
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims abstract description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 8
- 239000012530 fluid Substances 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000002347 injection Methods 0.000 claims description 5
- 239000007924 injection Substances 0.000 claims description 5
- 125000004432 carbon atom Chemical group C* 0.000 claims description 2
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims 1
- 238000006073 displacement reaction Methods 0.000 abstract description 2
- 150000002500 ions Chemical class 0.000 description 8
- 239000000543 intermediate Substances 0.000 description 5
- 241001208007 Procas Species 0.000 description 3
- 238000000605 extraction Methods 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 2
- -1 ion hydrocarbons Chemical class 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000008016 vaporization Effects 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- YVPYQUNUQOZFHG-UHFFFAOYSA-N amidotrizoic acid Chemical compound CC(=O)NC1=C(I)C(NC(C)=O)=C(I)C(C(O)=O)=C1I YVPYQUNUQOZFHG-UHFFFAOYSA-N 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001722 carbon compounds Chemical class 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 description 1
- 230000007775 late Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
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
- E21B43/166—Injecting a gaseous medium; Injecting a gaseous medium and a liquid medium
- E21B43/168—Injecting a gaseous medium
-
- 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
- E21B43/164—Injecting CO2 or carbonated water
-
- 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
- E21B43/34—Arrangements for separating materials produced by the well
- E21B43/40—Separation associated with re-injection of separated materials
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
2069735 9110040 PCTABScor01 A process for in-situ enrichment of gas used in miscible flooding in a subterranean hydrocarbon-bearing reservoir. A drive gas such as methane, lean natural gas, nitrogen, carbon dioxide or mixtures thereof is used to immiscibly displace formation hydrocarbons. After gas breakthrough the produced fluid is separated into oil and gas components. The separated gas, which has been enriched with intermediate hydrocarbon compounds extracted from the formation hydrocarbons, is mixed with the drive gas injected into the reservoir so as to enrich the injected gas sufficiently to cause miscible displacement of the formation hydrocarbons. When the drive gas is carbon dioxide, methane and/or nitrogen may be extracted from the separated gas prior to being mixed with the drive gas.
Description
WO 91/100~0 ~ PCr/US~0/04964 PROCE~SS FOR li~l ~;lTU ~NR3CHMENT ~F GAS 20~973 USED IN MilSGlBLE Fl OC)BINIG
Flel~ ot tho InYentlon Th~ pres~nt invention r~lates to th~ pr~paration of gases us~d in the os miscibl0 flooding of a subterrar,gan hydrocarbon-bearing formation, and mor0 particul~rly, to a process for in-situ 0nrichm~nt of a gas to improve the miscibility of the gas and hydrocarbons pr0s~nt in a subt~rranean hydrocarbon-bearing f~rmation.
E~ack~roun~ Qt the Inventlon It is w~ll known to injact miscibl0 gasos into a subterranean hydrocarbon-b~aring r~s~rvoir to impr~vo production of hydrocarbons frvm the forma~ion through miscibl~ flooding. Miscibl~ flooding occurs when a gas injected into th~ tormati~n mixes with hydrocarbons in the forrnation at the ambient temperature and pressur0 of the tormation to displace the hydrocarbons. This ph~nomenon occurs as a result of intermediat~
~ ~ hydr~carbon compounds in th~ inja~ed gas cond0nsing upon contact with : ~ the format~ion hydrocarbons and altoring th~ composition of the formation hydrocarbons. It suffici~nt amounts of hydrocarbon in~Qrmediates cond~nse from the gas an~ mix with th~ formation hydrocarbons, th~ flooding gas arld 20 ~ formation hydrocarbons b~com0 miscible. This phenomenon is r~ferred to as the condensing mechanism.: The inj~ct~d; gas may aiso become misoible :~ with th~ formation hydrocarbons through the vaporizing rrechanism in which int~m~di~te hydrocarbons are vaporized from forrnation hydrocarbons into the injected gas, ~hus crea~ing`miscibility. Flooding ~ subterranean formation with a gas which is miscibl~ with hydrocarbons p~sent in th~ formation v3rsus a gas which is~ immiscibl~ with these hydrocarbons can result in r~covery of up to about 10-15 volume.% of incremental hydrocarbons in place in th~ forrnation.
A process for! misci~ly 110bdin~ a subgerranean forma~ion uti,izing a gas, such as carbon dioxide, m~hane, or nitrogen, which does no~ contain s ~ ~ int~rmediate hydrocarbans~and which is capabl~ of extracting or vaporizing . Sormation hydrocar~ons so ~hat the gas becomes enriched with extracted formation hydrocarbons is conduct0d by raising the operating pressure of the , flo~din~ proc~ss so as ~o reach th~ minimum miscibility pr~ssure, that is, the rninimum pr~ssure at which the gas is miscible in the formation hydrocarbons Th~ proc0ss of miscible floodir~g can also bo conducted by enriching the gas ,~
.
Flel~ ot tho InYentlon Th~ pres~nt invention r~lates to th~ pr~paration of gases us~d in the os miscibl0 flooding of a subterrar,gan hydrocarbon-bearing formation, and mor0 particul~rly, to a process for in-situ 0nrichm~nt of a gas to improve the miscibility of the gas and hydrocarbons pr0s~nt in a subt~rranean hydrocarbon-bearing f~rmation.
E~ack~roun~ Qt the Inventlon It is w~ll known to injact miscibl0 gasos into a subterranean hydrocarbon-b~aring r~s~rvoir to impr~vo production of hydrocarbons frvm the forma~ion through miscibl~ flooding. Miscibl~ flooding occurs when a gas injected into th~ tormati~n mixes with hydrocarbons in the forrnation at the ambient temperature and pressur0 of the tormation to displace the hydrocarbons. This ph~nomenon occurs as a result of intermediat~
~ ~ hydr~carbon compounds in th~ inja~ed gas cond0nsing upon contact with : ~ the format~ion hydrocarbons and altoring th~ composition of the formation hydrocarbons. It suffici~nt amounts of hydrocarbon in~Qrmediates cond~nse from the gas an~ mix with th~ formation hydrocarbons, th~ flooding gas arld 20 ~ formation hydrocarbons b~com0 miscible. This phenomenon is r~ferred to as the condensing mechanism.: The inj~ct~d; gas may aiso become misoible :~ with th~ formation hydrocarbons through the vaporizing rrechanism in which int~m~di~te hydrocarbons are vaporized from forrnation hydrocarbons into the injected gas, ~hus crea~ing`miscibility. Flooding ~ subterranean formation with a gas which is miscibl~ with hydrocarbons p~sent in th~ formation v3rsus a gas which is~ immiscibl~ with these hydrocarbons can result in r~covery of up to about 10-15 volume.% of incremental hydrocarbons in place in th~ forrnation.
A process for! misci~ly 110bdin~ a subgerranean forma~ion uti,izing a gas, such as carbon dioxide, m~hane, or nitrogen, which does no~ contain s ~ ~ int~rmediate hydrocarbans~and which is capabl~ of extracting or vaporizing . Sormation hydrocar~ons so ~hat the gas becomes enriched with extracted formation hydrocarbons is conduct0d by raising the operating pressure of the , flo~din~ proc~ss so as ~o reach th~ minimum miscibility pr~ssure, that is, the rninimum pr~ssure at which the gas is miscible in the formation hydrocarbons Th~ proc0ss of miscible floodir~g can also bo conducted by enriching the gas ,~
.
2 Pcr/~s~o/o~s64 ~nriching the gas with hydrocarbon int~rmodiates prior to injectin~ the gas into the subterr~n~an ~ormation. The resulting enriched gas is a multicompon~nt gas cont~ining sufficient hydrocarb~n intermediates to rend~r the enrich~d gas substantially miscibl0 in formation hydrocarbons 05 upon injaction into the formation.
An example of one typa of ~nrichment process is found in U.S. Patent No. 4,52g,037 which disclos0s th~ formation of a drive gas comprised of carbon dioxide and int~rm~diato hydrocarbons. A surface facility is ~mploy2d to maintain multipt~ phas~ mixtures of cr~d~ oil and carbon dioxid~ in an ~xtraction zon~ ~rom which it is withdrawn for subs~qu~nt inj~ction into a reser~oir. Th0 cost of th~ n0cessary faciliti~s to extract hydrocarbons and mix th0 axtract~d hydrocarbons with a drive gas can, however, be prohibitively ~xp~nsive for som0 reservoirs.
-In ord~r to reduc~ the cost of drive gas preparation it has been sugg~st~d to utilize ths mixing that takes plaoe in ~he reservoir to create an ~nriched gas. U.S. Patent NQ. 2,875,832, ~or sxample, discloses a process which involves introducing carbon dioxid0 into th3 oil reservoir and recycling th0 ~asoous afflu~nt back into th~ formation. B00auss tha process requires th~ injection of carbon dioxide and mixtur~s of carbon dioxide arld effluent gasas to b~ carri~d out at eiavated pr~ssu~s, i.~ at l~ast about 300 psi, the overall process is still too exp~nsivo for rnany reservoirs.
In rnany instanc~s, th~ minimum miscibility pressure of a subterrar~ean hydrocarbon-bQaring tormation may 0xcead th~ ~racture pressure of the f~rmation th~reby rendering miscibl3 fl~oding impractical. At offshore - 25 locations whare spaca is at a premiurn and gas~ plants are nonexistent, oparators may be forced to r~inject gas into a produ ing subterranean forma~ion. Thus, a ne~d exists ~or a procass for preparing miscible gases for inj~ction into a subterranoan hydrocarbon-bearing formation.
It is thsrefere a broad object of th~ pres~nt invention to reduce ~he cost of a miscibl~ flooding proc~ss, and a mcre specifio ojbjeot to reduoe the cost of a gas enrichment process.
~t is a turther object of th~ pres~nt invsntion to provide a process for enriching ~ gas ~or miscible flooding wh~re surface faoilities must be minirniz~d due to oonstrai~ts on availabl0 spac~.
Brief S~mmary of ~he Invention The present inYention involYes preparation of an enriched gas in a simpie economioal manner and does not require the gas to be introduced to , wo 91/10040 3 P~/us~ 47 3 5 a subt~rran0an formation at un~onomical hi~h pressures According to the invention a first gas, which is a drive gas containing no intermediate hydrocarbon compoun~s, is inject~d into a sublorran~an hydrocarbon~
bearing formation th~ ambiQnt pr~ssur~ of which is less than the minimum 05 miscibility pr~ssure of the gas and th~ formation hydroearbons. The gas is injec~ed und~r ambieng forma~ion t~mperatur~ and pressure conditions and is ~mploy~ in an immiscible flooding op~ration. The formation is continued to bo immiscibly displaced until gas breakthrough. after whioh the produced fluid is s~parated into oil and ~nrich~d gas. Th~ ~nriched gas is mixed with ~he ~irst ~as and ths mi~ur~ is th~n inj~cted into th~ formation to miscibly displacs the formation hydrocarbons.
Th~ enriohed g~s comprises th~ original drive gas which has been enr~ched with intermediata hydrocarbons extracted from the hydrocarbons preserlt in the formation. Preferably, ths original gas is carbon dioxide, nitrogen, methane, l~an natural gas or rnixtures thereof. When the gas used is carbon dioxide, methane and nitrog~rl in the separated gas are desirably ~xtracted prior to mixing with th~ first gas.
Tho proc~ss is simple but sff~ctive1 permitting formation hydrocarbons to be produced through miscibl~ displac~ment without requiring e%pensiYe - 20 operating conditions or equipm~nt.
Thass and oth~r asp~c~s o~ th~ inv~ntion, as woll as other ben~fits, will ~; reàdily bo ascertain~d ~rom th~ mor~ d~tailed description of ths preferred embodiment nf tha~ invention which follows.
:; ~ Brl~t Deecrlptlon ot ths l:)rawinys ~ Th~ accompanying drawing, which is incorporated in and forms a part f th~ specification, illustrat~s the pr~sent invention and, together with the :~ description, s~rves to explain th~ principles o~ the invention. In the drawing:
FIG. 1 is a schematic flow diagram of tho gas enrichment process of the prssent invention.
~: 30 Description of th~ Pr~ferred Embodiment - - Inslead of providing ~xp~nsiv~ sur~ace facilities and equipment lo ~ j . s%tract intermediate hydrocarbons from produced formation hydrocarbons : ~ and mix them with a dri~ gas prior to inj~c~ing th~ dri\~e gas into asubterran~an hydrocarbon-b~aring formation to be produced through ~ 1 35 misciblc displacement of hydrocarbons, and instead of introducing gas into : I the formation under high pres~ures in order to reach the minimum miscibility , .. . .
~ ,....
, . ~
,~
WO 91tlO040 2 ~ ~i 9 7 r/ ~ pcr/usso/o4964 prassure o~ th~ r~servoir ~Iydrocarbons and the gas, th~ pres~nt invent,,"l provides for a first phase involving an immiscible floodin~ op~ration at ambient r~s~oir temperaturs an~ pr~ssur~. Ref6rring to FIG. 1, a source 10 of a drive gas is delivar~d through conduit 12 to a pump 14 which injects the 05 gas through tha injection wcll 1~ into the subtorranean hydrocarbon-bearing ~, formation or reservoir 18. The gas is s~lected such that the ambient ~ormation pr~ssure is less than tha minimum miscibility pr~ssure of the ~ormation hydrocarbons and the gas, thus assuring that the flooding operation is irnmiscibl~ in natura.
The gas may b~ any suitabl~ gas known to function as a driv~ gas, such as carbon dioxide, mathan~ an natural gas, or mixtures thereof, which cluring the proc~ss of displacing th~ formation hydrocarbons at the ambisnt pressur~ and t~mp~ra~ura of th0 formation is capable of extracting hydrocarbon intermediat~ compounds from the formation hydrocarbons and 15 thereby b~coming ennch~d. As utilized throughout this specification. the ~erm "l~an natural gas" r~fers to a natural gas having at 10ast gO mole %
me~hane and th~ tarms "interm~diat~ hydrocarbons" and ~intermediate :~ hydrocarbon compounds" ar~ used int3rchang~ably and each encompass those hydrocarbon compounds having ~rom 2 to 6 carbon atoms. In this r~sp~c~, th~ ~orma~ion itsalf acts as a large extraction chamb~r. Un~er ambi~nt ~ormation conditions, howover, the driv~ gas is not enriched : sufficiently to dev~lop miscibility with the oil.
Th~ immiscible flooding op~r~tion continues, with formation hydrocarbons being produc0d through th~ production well 20 to surfac~
2~ cond~it 24, until d:rive gas br~ak~hrough occurs at the production well. At this time th0 natur~ of th~ op~ration changes.: R~rring again to FIG. 19 it will be s~sn that the produced forma~ion hydro~arbons and the enriched gas are dir~ted ~through conduit 24 to a separator 26 :which operates under a pr~ssure tha~ pr~Yents substantial ioss of enrichmant ~rom the gas, i.e. at a pressure b~low ths mi~limum mis~ibiiity pr~ssure of the drive gas and the producad hydrocarbons. The saparator oil resulting from this opèration is deliv~r~d through lin~ 28 for fu~her US9 or sal~. It ~will bs lunderstood that in conventional separation procass~s, separator oil and th~:prod~Jced enriched 1 gas would be sent to a gas procQssing plant wherei~n ~he produced enriched 3~ ~ gas would b~ separated into th~ originai drive gas and the hydrocarbon - ¦ compounds extracted from th~ reservoir. In this process, however, the hydrocarbon components are retained and the enriched gas i5 direc~ed through lin~ 30 to the conduit 12 and is mix~d with the drive gas from the ". ~ , WO ~1/10~0 5 2 0 ~ ~ 7 3 ~ PcrlUS90/~4~64 supply 10, so that a mixtur0 of drive gas and enriched gas is injected into t~e reseNoir 1 8.
The amount of enriched ~as and its degree of ~nrichment ar~ such that th~ gaseous mixtur~ injected into ~hs reservoir is capable of miscibly 05 displacing the lormation hydrocarbons in the lormation under ambient formation pressure and temp6ra~ur~ conditions. This is brought about by the int0rmediate hydrocarbon compounds transf~rring or condensing ~rom the gas phas~ to th~ liqui~ hydrocarbon phas~, and the liquid hydrocarbon phas0 thus becoming ~nriched with ths hydrocarbon intermediates to lO d~v~lop a miscible fluid. Th0 produced miscible fluid is s0parated at the separator 26, as was th~ produc0d formation hydrocarbons and enrich~d gas at the gas breakthrough stag~ of th~ proc~ss, and the r~sulting enriched gas is recyclod an~ reinject~d in th~ manner pr~viously described.
As mentioned, th~ drive gas sholJld be carbon dioxide, nitrogen, m~thane, lean natural gas or mixtur~s thereof. Wh~n using a drive gas containing methan~, methane in th~ enrich~d gas from separator 26 will be merely additive when the endch~d gas is introduc~d to the conduit 12. When the drive gas does not contain m~thane or nitrogen it will be advantageous no~ to mix m~than~ or nitrogan trorn the ~nriched gas with it. In order to 20 pr~vent this ~rom oecurring, th~ 0nrich~d gas leaYing s~parator 26 may be directed ~hrough line 32 to an ~xtraction vassel (not illustrated). ~ portion ofthe separator oil may also ~be introduced into the extraction vessel. The extraction vess~l is operated und~r conditions, well krlown to those skilled in the art, ~o flash methane~and/or nitrogen from the~enriched gas. The enriched ; gas then is directe~d ~o th~ conduit 12 leading from the drive gas supply and the miscible flood process is ~ontinusd as described above in connection with FIG. 1. ~ ~ ~
The following exampl~ demonstrates the practice and utility of the pr0sent invention but is~not to be constru~d as limiting the scope thereof.
3 ~ t ~ E~AM P LE~ I !
In a subterranean hydrocarbon-bearing to,mation havir~g a minimum miscibility pressure measured at 5400 psi with a lean n~tural gas having 92 m~l0 % methane~and 8 mole % 2thane and ths ~ormatiorl hydrocarbons in accordance with the~method disclosed in U.S. Pat~nt No. 4,610,1~0 and a - 3, temperatlJre ot 240 F and pressure of 5000 psi, a lean natural gas consisting ~: of 92 mole % methane and 8 mole % e~hane is injected into the formation via an jnjBCtjOn well in fluid cornmunication with the formation. Formation , ,~i/~
wo 91/10040 P~/USgO/04964 hydrocaræ~s~ ~r9~ 3produc~d ~rom a separate production well in flu,_ communic~tion with with th~ ~ormation. The lean natural gas is enriched with in~0rmediatc hydrocarbons during contact in situ with formation hydrocarbons. Once th~ enrich~d l~an natural gas breaks through the 05 formation and is produc0~ together with tormation hydrocarbons via the production well, the produced formation hydrocarbons and th~ enriche~ lean natural gas are transported to a separator (26). The enriched lean natural gas from the separator is determined to hav~ a composition ot 85.4 mole %
methane, 7 mole % ethane, 4 mol~ % propan0, 2 mole /O butane, 1.2 mole /~
pontane and .4 mole % h~p~an~. Since th~ minimum miscibility pressure of the enriched lean natural gas is rneasured at 4900 psi, inj~ction of this enriched lean natural gas into th~ formation via the injection well should result in miscible flooding of the formation hydrocarbons.
Th~ process of th0 present invention rnay be incorporated into conventional gas flooding operations, such as water-alt~rnating gas flooding of a hydrocarbon-bearing formation disclosed in U.S. Patent No. 4,846,27 which is incorporated herein by this refer~nce, as will be evident to the skilled artisan. Further, it is importan~ to note that even in the instance where the procoss of th~ present invantion do~s not r~sult in miscibls flooding in a given formation, the procass may still enhancs oil recovery from such ~; formation where incr~ased ~ormation hydrocarbon swelling and/or viscosity redu~ion is achi~ved by the process of ths present invention.
~Whil~ th~ foregoing preferr0d embodiments of the invention have been described and shown, it is understood that the alternatives and 2~ ~ modifications, such as thos~ suggested and ethers, may be made thereto and tall within the scopa of ~he inven~ion.
::: ~ : :
, . j : j , .
~1 ;l .~
'~, ~,~
An example of one typa of ~nrichment process is found in U.S. Patent No. 4,52g,037 which disclos0s th~ formation of a drive gas comprised of carbon dioxide and int~rm~diato hydrocarbons. A surface facility is ~mploy2d to maintain multipt~ phas~ mixtures of cr~d~ oil and carbon dioxid~ in an ~xtraction zon~ ~rom which it is withdrawn for subs~qu~nt inj~ction into a reser~oir. Th0 cost of th~ n0cessary faciliti~s to extract hydrocarbons and mix th0 axtract~d hydrocarbons with a drive gas can, however, be prohibitively ~xp~nsive for som0 reservoirs.
-In ord~r to reduc~ the cost of drive gas preparation it has been sugg~st~d to utilize ths mixing that takes plaoe in ~he reservoir to create an ~nriched gas. U.S. Patent NQ. 2,875,832, ~or sxample, discloses a process which involves introducing carbon dioxid0 into th3 oil reservoir and recycling th0 ~asoous afflu~nt back into th~ formation. B00auss tha process requires th~ injection of carbon dioxide and mixtur~s of carbon dioxide arld effluent gasas to b~ carri~d out at eiavated pr~ssu~s, i.~ at l~ast about 300 psi, the overall process is still too exp~nsivo for rnany reservoirs.
In rnany instanc~s, th~ minimum miscibility pressure of a subterrar~ean hydrocarbon-bQaring tormation may 0xcead th~ ~racture pressure of the f~rmation th~reby rendering miscibl3 fl~oding impractical. At offshore - 25 locations whare spaca is at a premiurn and gas~ plants are nonexistent, oparators may be forced to r~inject gas into a produ ing subterranean forma~ion. Thus, a ne~d exists ~or a procass for preparing miscible gases for inj~ction into a subterranoan hydrocarbon-bearing formation.
It is thsrefere a broad object of th~ pres~nt invention to reduce ~he cost of a miscibl~ flooding proc~ss, and a mcre specifio ojbjeot to reduoe the cost of a gas enrichment process.
~t is a turther object of th~ pres~nt invsntion to provide a process for enriching ~ gas ~or miscible flooding wh~re surface faoilities must be minirniz~d due to oonstrai~ts on availabl0 spac~.
Brief S~mmary of ~he Invention The present inYention involYes preparation of an enriched gas in a simpie economioal manner and does not require the gas to be introduced to , wo 91/10040 3 P~/us~ 47 3 5 a subt~rran0an formation at un~onomical hi~h pressures According to the invention a first gas, which is a drive gas containing no intermediate hydrocarbon compoun~s, is inject~d into a sublorran~an hydrocarbon~
bearing formation th~ ambiQnt pr~ssur~ of which is less than the minimum 05 miscibility pr~ssure of the gas and th~ formation hydroearbons. The gas is injec~ed und~r ambieng forma~ion t~mperatur~ and pressure conditions and is ~mploy~ in an immiscible flooding op~ration. The formation is continued to bo immiscibly displaced until gas breakthrough. after whioh the produced fluid is s~parated into oil and ~nrich~d gas. Th~ ~nriched gas is mixed with ~he ~irst ~as and ths mi~ur~ is th~n inj~cted into th~ formation to miscibly displacs the formation hydrocarbons.
Th~ enriohed g~s comprises th~ original drive gas which has been enr~ched with intermediata hydrocarbons extracted from the hydrocarbons preserlt in the formation. Preferably, ths original gas is carbon dioxide, nitrogen, methane, l~an natural gas or rnixtures thereof. When the gas used is carbon dioxide, methane and nitrog~rl in the separated gas are desirably ~xtracted prior to mixing with th~ first gas.
Tho proc~ss is simple but sff~ctive1 permitting formation hydrocarbons to be produced through miscibl~ displac~ment without requiring e%pensiYe - 20 operating conditions or equipm~nt.
Thass and oth~r asp~c~s o~ th~ inv~ntion, as woll as other ben~fits, will ~; reàdily bo ascertain~d ~rom th~ mor~ d~tailed description of ths preferred embodiment nf tha~ invention which follows.
:; ~ Brl~t Deecrlptlon ot ths l:)rawinys ~ Th~ accompanying drawing, which is incorporated in and forms a part f th~ specification, illustrat~s the pr~sent invention and, together with the :~ description, s~rves to explain th~ principles o~ the invention. In the drawing:
FIG. 1 is a schematic flow diagram of tho gas enrichment process of the prssent invention.
~: 30 Description of th~ Pr~ferred Embodiment - - Inslead of providing ~xp~nsiv~ sur~ace facilities and equipment lo ~ j . s%tract intermediate hydrocarbons from produced formation hydrocarbons : ~ and mix them with a dri~ gas prior to inj~c~ing th~ dri\~e gas into asubterran~an hydrocarbon-b~aring formation to be produced through ~ 1 35 misciblc displacement of hydrocarbons, and instead of introducing gas into : I the formation under high pres~ures in order to reach the minimum miscibility , .. . .
~ ,....
, . ~
,~
WO 91tlO040 2 ~ ~i 9 7 r/ ~ pcr/usso/o4964 prassure o~ th~ r~servoir ~Iydrocarbons and the gas, th~ pres~nt invent,,"l provides for a first phase involving an immiscible floodin~ op~ration at ambient r~s~oir temperaturs an~ pr~ssur~. Ref6rring to FIG. 1, a source 10 of a drive gas is delivar~d through conduit 12 to a pump 14 which injects the 05 gas through tha injection wcll 1~ into the subtorranean hydrocarbon-bearing ~, formation or reservoir 18. The gas is s~lected such that the ambient ~ormation pr~ssure is less than tha minimum miscibility pr~ssure of the ~ormation hydrocarbons and the gas, thus assuring that the flooding operation is irnmiscibl~ in natura.
The gas may b~ any suitabl~ gas known to function as a driv~ gas, such as carbon dioxide, mathan~ an natural gas, or mixtures thereof, which cluring the proc~ss of displacing th~ formation hydrocarbons at the ambisnt pressur~ and t~mp~ra~ura of th0 formation is capable of extracting hydrocarbon intermediat~ compounds from the formation hydrocarbons and 15 thereby b~coming ennch~d. As utilized throughout this specification. the ~erm "l~an natural gas" r~fers to a natural gas having at 10ast gO mole %
me~hane and th~ tarms "interm~diat~ hydrocarbons" and ~intermediate :~ hydrocarbon compounds" ar~ used int3rchang~ably and each encompass those hydrocarbon compounds having ~rom 2 to 6 carbon atoms. In this r~sp~c~, th~ ~orma~ion itsalf acts as a large extraction chamb~r. Un~er ambi~nt ~ormation conditions, howover, the driv~ gas is not enriched : sufficiently to dev~lop miscibility with the oil.
Th~ immiscible flooding op~r~tion continues, with formation hydrocarbons being produc0d through th~ production well 20 to surfac~
2~ cond~it 24, until d:rive gas br~ak~hrough occurs at the production well. At this time th0 natur~ of th~ op~ration changes.: R~rring again to FIG. 19 it will be s~sn that the produced forma~ion hydro~arbons and the enriched gas are dir~ted ~through conduit 24 to a separator 26 :which operates under a pr~ssure tha~ pr~Yents substantial ioss of enrichmant ~rom the gas, i.e. at a pressure b~low ths mi~limum mis~ibiiity pr~ssure of the drive gas and the producad hydrocarbons. The saparator oil resulting from this opèration is deliv~r~d through lin~ 28 for fu~her US9 or sal~. It ~will bs lunderstood that in conventional separation procass~s, separator oil and th~:prod~Jced enriched 1 gas would be sent to a gas procQssing plant wherei~n ~he produced enriched 3~ ~ gas would b~ separated into th~ originai drive gas and the hydrocarbon - ¦ compounds extracted from th~ reservoir. In this process, however, the hydrocarbon components are retained and the enriched gas i5 direc~ed through lin~ 30 to the conduit 12 and is mix~d with the drive gas from the ". ~ , WO ~1/10~0 5 2 0 ~ ~ 7 3 ~ PcrlUS90/~4~64 supply 10, so that a mixtur0 of drive gas and enriched gas is injected into t~e reseNoir 1 8.
The amount of enriched ~as and its degree of ~nrichment ar~ such that th~ gaseous mixtur~ injected into ~hs reservoir is capable of miscibly 05 displacing the lormation hydrocarbons in the lormation under ambient formation pressure and temp6ra~ur~ conditions. This is brought about by the int0rmediate hydrocarbon compounds transf~rring or condensing ~rom the gas phas~ to th~ liqui~ hydrocarbon phas~, and the liquid hydrocarbon phas0 thus becoming ~nriched with ths hydrocarbon intermediates to lO d~v~lop a miscible fluid. Th0 produced miscible fluid is s0parated at the separator 26, as was th~ produc0d formation hydrocarbons and enrich~d gas at the gas breakthrough stag~ of th~ proc~ss, and the r~sulting enriched gas is recyclod an~ reinject~d in th~ manner pr~viously described.
As mentioned, th~ drive gas sholJld be carbon dioxide, nitrogen, m~thane, lean natural gas or mixtur~s thereof. Wh~n using a drive gas containing methan~, methane in th~ enrich~d gas from separator 26 will be merely additive when the endch~d gas is introduc~d to the conduit 12. When the drive gas does not contain m~thane or nitrogen it will be advantageous no~ to mix m~than~ or nitrogan trorn the ~nriched gas with it. In order to 20 pr~vent this ~rom oecurring, th~ 0nrich~d gas leaYing s~parator 26 may be directed ~hrough line 32 to an ~xtraction vassel (not illustrated). ~ portion ofthe separator oil may also ~be introduced into the extraction vessel. The extraction vess~l is operated und~r conditions, well krlown to those skilled in the art, ~o flash methane~and/or nitrogen from the~enriched gas. The enriched ; gas then is directe~d ~o th~ conduit 12 leading from the drive gas supply and the miscible flood process is ~ontinusd as described above in connection with FIG. 1. ~ ~ ~
The following exampl~ demonstrates the practice and utility of the pr0sent invention but is~not to be constru~d as limiting the scope thereof.
3 ~ t ~ E~AM P LE~ I !
In a subterranean hydrocarbon-bearing to,mation havir~g a minimum miscibility pressure measured at 5400 psi with a lean n~tural gas having 92 m~l0 % methane~and 8 mole % 2thane and ths ~ormatiorl hydrocarbons in accordance with the~method disclosed in U.S. Pat~nt No. 4,610,1~0 and a - 3, temperatlJre ot 240 F and pressure of 5000 psi, a lean natural gas consisting ~: of 92 mole % methane and 8 mole % e~hane is injected into the formation via an jnjBCtjOn well in fluid cornmunication with the formation. Formation , ,~i/~
wo 91/10040 P~/USgO/04964 hydrocaræ~s~ ~r9~ 3produc~d ~rom a separate production well in flu,_ communic~tion with with th~ ~ormation. The lean natural gas is enriched with in~0rmediatc hydrocarbons during contact in situ with formation hydrocarbons. Once th~ enrich~d l~an natural gas breaks through the 05 formation and is produc0~ together with tormation hydrocarbons via the production well, the produced formation hydrocarbons and th~ enriche~ lean natural gas are transported to a separator (26). The enriched lean natural gas from the separator is determined to hav~ a composition ot 85.4 mole %
methane, 7 mole % ethane, 4 mol~ % propan0, 2 mole /O butane, 1.2 mole /~
pontane and .4 mole % h~p~an~. Since th~ minimum miscibility pressure of the enriched lean natural gas is rneasured at 4900 psi, inj~ction of this enriched lean natural gas into th~ formation via the injection well should result in miscible flooding of the formation hydrocarbons.
Th~ process of th0 present invention rnay be incorporated into conventional gas flooding operations, such as water-alt~rnating gas flooding of a hydrocarbon-bearing formation disclosed in U.S. Patent No. 4,846,27 which is incorporated herein by this refer~nce, as will be evident to the skilled artisan. Further, it is importan~ to note that even in the instance where the procoss of th~ present invantion do~s not r~sult in miscibls flooding in a given formation, the procass may still enhancs oil recovery from such ~; formation where incr~ased ~ormation hydrocarbon swelling and/or viscosity redu~ion is achi~ved by the process of ths present invention.
~Whil~ th~ foregoing preferr0d embodiments of the invention have been described and shown, it is understood that the alternatives and 2~ ~ modifications, such as thos~ suggested and ethers, may be made thereto and tall within the scopa of ~he inven~ion.
::: ~ : :
, . j : j , .
~1 ;l .~
'~, ~,~
Claims (7)
[received by the International Bureau on 2 May 1991 (02.05.91) ;
original claims 1-9 replaced by amended claims 1-7 (2 pages)]
1. A process for preparing enriched gas for use in miscibly displacing formation hydrocarbons present in a subterranean hydrocarbon-bearing formation, comprising the steps of:
injecting a first gas into a subterranean hydrocarbon-bearing formation at ambient formation temperature and pressure conditions via an injection well in fluid communication with the formation, the ambient formation pressure being less than the minimum miscibility pressure of the first gas with the formation hydrocarbons, and the first gas having the ability to extract intermediate hydrocarbon compounds from the formation hydrocarbons at ambient formation temperature and pressure conditions thereby becoming an enriched gas;
immiscibly displacing formation hydrocarbons with the first gas until breakthrough of the enriched gas at a production well in fluid communication with the formation;
separating the enriched gas from the produced formation hydrocarbons after said breakthrough of the enriched gas; and mixing the enriched gas with the first gas wherein the mixed gases are sufficiently enriched so as to be capable of miscibly displacing formation hdyrocarbons in said formation under said ambient formation temperature and pressure conditions.
injecting a first gas into a subterranean hydrocarbon-bearing formation at ambient formation temperature and pressure conditions via an injection well in fluid communication with the formation, the ambient formation pressure being less than the minimum miscibility pressure of the first gas with the formation hydrocarbons, and the first gas having the ability to extract intermediate hydrocarbon compounds from the formation hydrocarbons at ambient formation temperature and pressure conditions thereby becoming an enriched gas;
immiscibly displacing formation hydrocarbons with the first gas until breakthrough of the enriched gas at a production well in fluid communication with the formation;
separating the enriched gas from the produced formation hydrocarbons after said breakthrough of the enriched gas; and mixing the enriched gas with the first gas wherein the mixed gases are sufficiently enriched so as to be capable of miscibly displacing formation hdyrocarbons in said formation under said ambient formation temperature and pressure conditions.
2. The process of claim 1, including the step of injecting the mixed gases into the formation via said injection well to miscibly displace the formation hydrocarbons.
3 The process of claim 1, wherein the first gas is a drive gas containing no intermediate hydrocarbon compounds.
4. The process of claim 1, wherein the first gas is a gas selected from the group consisting of methane, lean natural gas, nitrogen, carbon dioxide and mixtures thereof.
5. The process of claim 4, wherein the first gas is carbon dioxide.
6. The process of claim 4, wherein the first gas is either nitrogen or carbon dioxide, and wherein the process includes the further step of extracting methane from the separated enriched gas prior to mixing the enriched gas with the first gas.
7. The process of claim 1, wherein the intermediate hydrocarbon compounds comprise hydrocarbon compounds having from 2 to 6 carbon atoms.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US457,679 | 1989-12-27 | ||
| US07/457,679 US5074357A (en) | 1989-12-27 | 1989-12-27 | Process for in-situ enrichment of gas used in miscible flooding |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2069735A1 true CA2069735A1 (en) | 1991-06-28 |
Family
ID=23817711
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002069735A Abandoned CA2069735A1 (en) | 1989-12-27 | 1990-08-30 | Process for in-situ enrichment of gas used in miscible flooding |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5074357A (en) |
| AU (1) | AU6527190A (en) |
| CA (1) | CA2069735A1 (en) |
| GB (1) | GB2251257A (en) |
| IE (1) | IE903839A1 (en) |
| WO (1) | WO1991010040A1 (en) |
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| EA005023B1 (en) * | 2000-12-13 | 2004-10-28 | Валерий Кушниров | Method foe recovering residual nonrecoverable from depleted oil formations |
| DE60227355D1 (en) * | 2001-03-15 | 2008-08-14 | Alexei Leonidovich Zapadinski | METHOD FOR DEVELOPING A CARBON STORAGE STORAGE AND PLANT COMPLEX FOR IMPLEMENTING THE PROCESS |
| US6620091B1 (en) | 2001-09-14 | 2003-09-16 | Chevron U.S.A. Inc. | Underwater scrubbing of CO2 from CO2-containing hydrocarbon resources |
| US20090165376A1 (en) | 2007-12-28 | 2009-07-02 | Greatpoint Energy, Inc. | Steam Generating Slurry Gasifier for the Catalytic Gasification of a Carbonaceous Feedstock |
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| US8733459B2 (en) | 2009-12-17 | 2014-05-27 | Greatpoint Energy, Inc. | Integrated enhanced oil recovery process |
| WO2011084581A1 (en) * | 2009-12-17 | 2011-07-14 | Greatpoint Energy, Inc. | Integrated enhanced oil recovery process injecting nitrogen |
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| CA2815243A1 (en) | 2010-11-01 | 2012-05-10 | Greatpoint Energy, Inc. | Hydromethanation of a carbonaceous feedstock |
| US8881810B2 (en) * | 2011-03-03 | 2014-11-11 | Halliburton Energy Services, Inc. | Dispersing separated hydrocarbon gas into separated oil during surface well testing for improved oil mobility |
| WO2012166879A1 (en) | 2011-06-03 | 2012-12-06 | Greatpoint Energy, Inc. | Hydromethanation of a carbonaceous feedstock |
| CN103974897A (en) | 2011-10-06 | 2014-08-06 | 格雷特波因特能源公司 | Hydromethanation of a carbonaceous feedstock |
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| WO2017140629A1 (en) * | 2016-02-16 | 2017-08-24 | Shell Internationale Research Maatschappij B.V. | System and method of enhanced oil recovery combined with a gas lift |
| NO20170525A1 (en) * | 2016-04-01 | 2017-10-02 | Mirade Consultants Ltd | Improved Techniques in the upstream oil and gas industry |
| WO2020072514A1 (en) * | 2018-10-02 | 2020-04-09 | University Of Houston System | Optimization technique for co2-eor miscibility management in an oil reservoir |
| CN114856511A (en) * | 2021-02-03 | 2022-08-05 | 中国石油化工股份有限公司 | Nitrogen gas miscible flooding method |
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| US2217749A (en) * | 1939-01-26 | 1940-10-15 | Pan American Production Compan | Liquid recovery and gas recycle method |
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| US4664190A (en) * | 1985-12-18 | 1987-05-12 | Shell Western E&P Inc. | Process for recovering natural gas liquids |
| NL8600209A (en) * | 1986-01-29 | 1987-08-17 | Tno | METHOD AND APPARATUS FOR DETERMINING THE QUANTITY OF DISPERSED SOLID MATERIAL IN A LIQUID. |
| US4846276A (en) * | 1988-09-02 | 1989-07-11 | Marathon Oil Company | Water-alternating-gas flooding of a hydrocarbon-bearing formation |
-
1989
- 1989-12-27 US US07/457,679 patent/US5074357A/en not_active Expired - Fee Related
-
1990
- 1990-08-30 WO PCT/US1990/004964 patent/WO1991010040A1/en active Application Filing
- 1990-08-30 CA CA002069735A patent/CA2069735A1/en not_active Abandoned
- 1990-08-30 AU AU65271/90A patent/AU6527190A/en not_active Abandoned
- 1990-10-25 IE IE383990A patent/IE903839A1/en unknown
-
1992
- 1992-02-06 GB GB9202553A patent/GB2251257A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| GB2251257A (en) | 1992-07-01 |
| WO1991010040A1 (en) | 1991-07-11 |
| US5074357A (en) | 1991-12-24 |
| GB9202553D0 (en) | 1992-04-29 |
| IE903839A1 (en) | 1991-07-03 |
| AU6527190A (en) | 1991-07-24 |
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