Miscible, Polymer and Thermal Enhanced Oil Recovery Recov ery Processes Proc esses Ins tr uc to r: Dr. M ari a A. Barr uf et Buenos Air es
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Enhanced Oil Recovery (EOR) Processes Enhanc ed o il r ecovery (EOR) Enhanced pro cess ess in cl ude pr ocesse ud e all m eth od s th at us e ext ern al s ou rc es o f energ energyy and /or materi als to reco recovver er o il th at cann ot b e pro du ced, eco nom all y econ omiiccall by c on vent io nal me ans ans..
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Currently Used EOR Processes Waterflooding Thermal methods steam stimulation, steamflooding, hot water drive, in-situ combustion 8/12/2008
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Currently Used EOR Processes Chemical methods Polymer, surfactant, Caustic, and micellar/polymer flooding. Miscible / Immiscible methods Hydrocarbon gas CO2, nitrogen, flue gas Microbial EOR (surfactant/chemical in-situ) 8/12/2008
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Waterflooding Injection Well
Water Injection Pump
Separation and Storage Facili ties
Production Well
1
2
1
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O ilZ o n e
2 I n je c t io nW a t e r
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Waterflooding Highlights Description Waterflooding consis ts of inje cting wate i ntto o tth hee re servo waterr in rese rv oiirr.. Water is in ject ed i n patte rn s or alo ng t he peri ph ery o f t he reservo ir . Mech ani sm s That I mp ro ve Reco very Efficiency Water d ri ve Inc reased pr ess ur e 8/12/2008
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Waterflooding Highlights Limitations High oil viscosities re sult i n high mobility ratios. Som e hete ro gene it y i s acceptable, bu t avoi d extensiv e fra ct ures. Challenges Poor com pati bil itityy bbetwee etwee n th e injecte inj ectedd wate patibil t he wate r and the rese rvo ir may cause cause form fo rmation ati on damage. damage . Subsur face fluid contr ol to divert inj ected wa ter and to shut off unde sirable produ ced fl uids.
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Sur fact ant /Pol ym er Flo od in g Injection Well
Water Injection
Separation and Storage Faciliti es
Production Well
Pump Surfactant Solution from Mixing Plant
4
1
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O i lZ o n e
2
S u rfa c ta n t
3
2
3
1
Polyme r Soluti on
4
Drive Water
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Sur fact ant /Pol ym er Flo od in g Highlights Description Surfa cta nt/ poly polym mer er fl oodin g co nsis ts o f inj ect slu g th at con c onttains ains water, ectiing ng a slug that su rf act ant , electr ol yt e (salt), us ually a co sol vent (a (alc oho er lco holl), ), fol low ed by pol ym ymer th ic kene d water. wate r. Mech ani sm s Tha t Impr ov e Reco very Effi ci enc y Interfa cial te nsi on reduc tio n (impr (improoves ves ti on di sp lace ment sw eep eff ic iency ). Mobil vess v olumetric s weep Mobiliity ty cont rol (impro (impr ove efficiency). 8/12/2008
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Sur fact ant /Pol ym er Flo od in g Highlights Limitations An areal sweep of more than 50% for waterflood is d esir ed. Relatively hom ogene ous for mati on. High amou nts of anhyd anhydrriitte, e, gyp sum , or c lays a re undesirable. Available systems provide optimum behavior with in a narrow s et of con diti ons. Wit h c omm erci all y ava il able sur facta nts , fo rm ati on w ater ch lo ri des sho ul d be <20,000 ppm and d iv alent i on s (Ca ++ and Mg ++) <500 ppm . 8/12/2008
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Sur fact ant /Pol ym er Flo od in g Highlights Challenges Com pl ex and expensiv expe ns iv e sy st em. Possi bili off chro matogr aphic sseparation bilittyy o chrom atographic eparation of chemicals. High adsor ption urfacta ptio n of ssurf acta nt. Intera ct een nt and pol ymer. ctiion onss betw betwee n su surrfacta fact ant ym er. Degr adation adatio n of cch hemic emi cals als at hig hi ghh t emp eratur erature. e.
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Pol ym er Flo od in g Injection Well Polymer So luti on from Mixing Plant
Water Injection
1
O i l Zone
Production We
ll
Pump
3
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Sepa rati on and Stora ge F acili ti es
2
2
Polym er Soluti on
1
3
Drive Water
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Pol ym er Flo od in g Highlights Description Pol ym er aug mente d waterflooding consists of a ddi ng wate r so lub le pol ymers to th e t he water b efor e it is inj ect ed i nto the re servo ir. Mech ani sm s That Impr ov e Reco very Efficiency Mobili ty co ntrol (improove vess volu metric ntro l (impr vol ume tric sw eep eff effiicciiency enc y). ).
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Pol ym er Flo od in g Highlights Limitations High oil vis vi sco cossit itiies es require aa hig her poly mer conc entra tion . entration. Resul ts are normally bett er ifi f tthe he poly polym er better mer flflo oood d is st art ed be befor wate arted for e th thee wa terr -oil r atio becom es exc gh. exceess ss ively iv ely hi hig h. Clays inc rease polym er adsorp tio n. poly mer Som e heterog eneity heterogene it y is acc ept abl e, but avo id ext ens iv e fr act ur es. If f ractu res a re pr esent , th e crosslinked or g elled poly mer techn iq ues ma y be pp li cable b e aapp cable.. 8/12/2008
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Pol ym er Flo od in g Highlights Challenges Lower injectivity than wit wi th hw water ater c an adv ers ely oilil p pro duc n rate s iin n th e adverse ly affe ct o rod ucttio ion rates the early st agess of the poly mer d.. stage polym er fflloo ood Acrylamide-type poly mers ositty y polym ers loo loossee visc vis cosi du e to sshhear ear degrada ti on , salin y and saliniitty diva lent ions . Xanthan gum pol ymers morre, e, are ym ers co cosstt mo sub ject to mic rob ial d degrada on, nd have egrada titio n, aand a grea ter p otentia l f or wellb ore plug gin g. 8/12/2008
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Pop ul ar en Ar gent in a Mic ro bi al EOR Mecanismos Costo
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Mis ci bl e Gas Flo od in g (CO2 Injection) Injection Well
Water Injection
Separation and Storag e Fa cil iti es
Production Well
Pump C O 2 Injection from Pipeline or Recycle
4
1
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Oil Zone
2
Oil Bank / Misci ble F ront
3
2
3
1
C O 2 and Water Zone
4
Drive Water
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Mis ci bl e Gas Flo od in g (CO2 Inj ect io n) Hig hl ig ht s Description CO2 flood ing con sist s of inj floo ding injeectin ctin g la rge quantiti es o f CO 2 (15% or mo re hyd carbon quantit ies hydrrooc arb on por e vol umes) in t he reserv oirir ttoo ffo orm reservo rm a miscible misc ibleflood. flood . Mech ani sm s Tha Thatt IImpr mp roov vee Reco Reco very Effi ci enc y CO2 extr act s th e lig ht -to -intermediate ext ract com pone ents fro m tth hee oil , and, if th ty e pressure is hi gh nough develops nough,,de velops misc ibili ibil ity ttoo dis place oil fro m t he re servo ir. reservo Visco sity reducti on / oil swelling. swe lling . reduct ion 8/12/2008
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Mis ci bl e Gas Flo od in g (CO2 Inj ect io n) Hig hl ig ht s Limitations
Very l ow V is co si ty of CO 2 results in poor poo r mobility control. Availability of CO2 Sur face Faci lilitties ies
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Mis ci bl e Gas Flo od in g (CO2 Inj ect io n) Hig hl ig ht s Challenges
Early brea kth rouugh gh of CO 2 causes prob lems. kt hro pro blems. Corros ion in produ cing we lls. The ne cessi ty of sepa ratin g CO 2 fr om sale abl e hyd roc arbo ns. R e -pre ssur ing ooff CO 2 for recycling. A large requirement of CO2 per inc reme nt al barrel pro ducced. ed. pr odu
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Mis ci bl e Gas Flo od in g (Hyd ro carb on Inj ect io n) Injection Well
Water Injection Pump
Separation and Storage Facili ti es
Producti on Well
HC Gas Injection from P ipeli ne or Recycle
4
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Oil Zone
2
Oil Bank / Miscible Front
3
2
3
1
HC and Water Zone
4
Drive Water
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Mis ci bl e Gas Flo od in g Hyd carb onn Inj ect n Hig hlliigght ht s Hydrrooca rbo Inje ctiioon High Description Description Hydroc arbon ga s flood ing cons istss ooff Hydro carbon con sist inje ctin g light hyd hydr roca oca rbons th rough the th e reservoi r to form a misc ible flood. Mech ani sm s t hat I mp ro ve Reco very Efficiency Visco sity reduct ion / oil swe lling / Viscos ity ng reduct ion / izing oil swe llindri g /ve. con densi or v apor g as
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Mis ci bl e Gas Flo od in g Hyd carb onn Inj ect n Hig hlliigght ht s Hydrrooca rbo Inje ctiioon High Limitations Mini mum depth is s et by the pre ss ssu ure re needed to main tain t he ge nera tedd nerate mis ci bililiity nges cib ty . The re qui red pressure pressur era ranges fr om abo ut 1,200 ps i f or th e LPG pr oc ess to 3,000-5,000 ps i f or th e Hig h Pre ss ur e Gas Driv e, depe nd in g o n t he oil . Dri ve, A steeply dipping formation is very desirable - permit permi ts s gr graavi vity ty st staabil biliza izatio tionn of the dis place ment that no rmally has an unf mob iliity ty ra tio . unfaavor voraable ble mobil ratio. 8/12/2008
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Mis ci bl e Gas Flo od in g Hyd carb onn Inj ect n Hig hlliigght ht s Hydrrooca rbo Inje ctiioon High Challenges
Viscous finge ring results in ppoor oor vert ic al and ho ri zon tal swee p efficiency. Large qu ant it ies of e xp ens iv e pr odu ct s are requ ir ed. pr odu ct m s are ir ed. Sol vent ay brequ e tr app ed and nnoott may recovered.
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Nitr og en / Flue Gas Floo di ng Injection Well
Water Injection Pump
Separati on and Storage Facilit ies
Producti on Well
N 2 Injection from Pipeline or Recycle
4
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Oil Bank / Miscibl e Front
3
2
3
1
N 2 and Water Zone
4
Drive Water
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Nitr og en / Flue Gas Floo di ng Highlights Description Nitr oge n or flf lue ue of gas injthat ectio n consi sts o ibl f inje ectin large quantit ies gas ma y be misc or g im mis e pressur e and oi l imm isccib ibllee dependi ng on th t he composition. Large volu vo lu mes ma y be inj ect ed, because of th e lo w cost. Nit rog en o r f lue ga s are als o c ons idere d f or use a s chase gases in hy dro carbo blle e and CO 2 carbonn - mi missci cib floods.
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Nitr og en / Flue Gas Floo di ng Highlights Mech ani sm s th at Imp ro ve Reco very Eff ic ienc y Vapo ri zes t he li gh ter c omp on ent s oo f onents th e cr ud e oi l and g enera tes miscib ilit thee pre ssure is hi gh ilityy ifif th enough. Pro vi des a gas dr ive iv e where wh ere a sig nif ica nt po onn of porrtitio of th thee reservoi reservo irr volume is ffiille gases. lle d with low -co cosstt g ases. 8/12/2008
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Nitr og en / Flue Gas Floo di ng Highlights Limitations Misc ibi lit y ccan an o nly be achi eved w witith h lig ht oi ls a t high ressur hig hppre ssur es; th erefo there fo re, deep r eserv oi rs are needed. A steeply dipping reservoir is desired to permit gra vit y s tabil izatio n o f t he di sp lace ment, as a very ment , wh ic h h has unf avora ble mobil avor able mobili ity ty ratio . 8/12/2008
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Nitr og en / Flue Gas Floo di ng Highlights Challenges Visc ous fifinge nge ring re sul ts in Viscous results in poo poorr verti cal nd hho orriizont al sw eep vert ic al aand zon tal swee p efficiency. Flu e gas in onn c can i njjecti ect io an c aus e corrosion. Non h yd roc arb onn gga ases ro carbo ses mu st b e sepa rate d f ro m s aleabl e gas. 8/12/2008
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Thermal ( Steamflooding )
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Steamflooding Highlights
Description Steamflooding consists
of inje cting about 80% qu ali ty st eam t o d is pl ace oil. Nor mal practi ce is to t o pr ecede and acc omp any tthe am d e by a cycl he ste st eam drriv ive cy cliicc ste am st imullation ation of tthe s timu he producing produ cing wells (called (calle d huf hu fff and pu p uffff). ).
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Thermal ( Steamflooding ) Highlights Mechani sms Imp Impr ove e Reco very EffThat ic ienc y rov Vis co si ty r edu ct io n / st eam distillation. Therm Thermaall exp ans io n. Sup Supp pllie iess pr p ressur ess uree to ddri ri ve oi oill to th thee produci ng we ll. 8/12/2008
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Thermal ( Steamflooding ) Highlights Limitations Applicable to viscous oils in massive, high perme abil it y sands ton es or uncon sol idate d sands . Oil satur saturaatiti ons mus t be high , and pay z ones shou ld be > 20 feet t hi ck to mi ni mi ze heat l os ses to adjace nt for mati ons . Steamflooded rese rvo ir s sho ul d be as sh all ow as sh oul po ss ib le, beca us e of excessi ve we ll bo re heat losses.
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Thermal ( Steamflooding ) Highlights More Lim it ati ons Steamflooding is not normally do ne in ca rbonate reservoirs. Sin utt 1/3 add ittiio nal oi oill recov Sinccee abo abou 1/3 of t he addi onal recoveered red is co ns um ed t o gene rate th e requi red st eam, the cost per i ncreme nta l barre oill iiss hhiigh. b arrell of oi gh. A low percentage of water -sensit ive cla ys is desired for go od injectivity . Challenges Adverse mobility ratio and channeling of steam.
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Screening Criteria: Criteri a: Depth Dept h
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Scr eeni ng C ri teri a: Oil Vis co si ty
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Screeni ng Cri teri a: Perm eabi li ty
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High permeability is usually better.
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Sum mary o f Screeni ng Criteria for EOR Methods
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Sum mary o f Screeni ng Criteria for EOR Methods
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Sum mary of Scr eeni ng Cri teri a fo r EOR Methods (cont.)
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Sum mary o f Screeni ng Criteria for EOR Methods (cont.)
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Eff ect on Eff ic ienc ies of Various EOR Methods Method
Displacement
Vert ical Sweep
Areal Sweep
Efficiency
Efficiency
Efficiency
Waterflooding
Maintains reservoi r pressure Enhanced wate r d rive displacing oil to producers
Decreases with increased heterogeneity
Dry HC Gas Injection
Maintains reservoi r pressure
Af fect ed by zonal pressure distribution
Cyclic Steam Injection
Oil viscosity reduction Reduces pressur e around the wellbore
Limi ted to nea rwellbore Dissolves pluggin g deposits around wellbore
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Af fect ed b y barriers, b affles, and boundaries Poor sweep if adverse mobility ratio
Limi ted to nea rwellbore Provides for higher injection rate s with subsequent steamflood 42
Eff ect on Eff ic ienc ies of Various EOR Methods Method
Steamflooding
Water Al ter nati ng Steam Process (WASP) Injection
In-situ Combustion 8/12/2008
Displacement
Vertical Sweep
Areal Sweep
Efficiency
Efficiency
Efficiency
Oil viscosity reduction Steam distill ation Pressure drives oil to producers
Steam injection can override because of gr avity segregation
Adver se mo bi lit y ratio
Water injected after steam causes the steam zone to collapse while tending to underrun the rese rvoi r
Reduces gr avity override Reduces vertical channeling
Improves areal conformance Reduces channeling
Oil viscosity reduction Pressure gradient drives oil Upgrades crude
Gravity segregation Adver se m obilit y ratio
Controlling flame front is difficult Adver se mo bi lit y ratio 43
Eff ect on Eff ic ienc ies of Various EOR Methods (cont.) Method
Displacement
Vertical Sweep
Areal Sweep
Efficiency
Efficiency
Efficiency
Surfactant Flooding
Reduces interfacial tension Increases water wettability Solubilizes oil Enhances mobility
Polymer Flooding
Au gm ents waterfl oo d Increa ses viscosi ty of injected w ater Decreases mobil ity of injected w ater
Provide s mobility control Forma tion plugging
Provide s m obility control Viscosity loss from shear degrada tion
Miscible Gas Flooding – CO2
Viscosity reduction Oil swelling Vaporizing gas Reduces interfacial tension
Ad verse mob il it y ratio. Gravity segrega tion. Asphaltene de posit ion n ear injectors Corrosion and scaling
Adver se mob il it y ratio Early b reakthro ugh and fingering Increases native permeability in a carbonate reservoir
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Improve s mobil ity ratio Improves areal conformance
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Eff ect on Eff ic ienc ies of Various EOR Methods (cont.) Method
Displacement Efficiency
Vertical Sweep Efficiency
Areal Sweep Efficiency
Miscible Gas Flooding – HC gas
Viscosity reduction Oil swelling Condensing/ vaporizing gas Reduces interfacial tension
Ad verse m obili ty ratio Gravity s egrega tion
Ad verse m obili ty ratio. Early brea kthrough and fingering
Nitrogen/Flue Gas Injection
Vapor izes ligh t oil components May be miscib le but mostly used for pressur e maintenance
Ad verse m obili ty ratio Gravity s egrega tion
Ad verse m obili ty ratio. Early brea kthrough and fingering
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Tech ni cal Con st rain ts CLA SSIFICATION OF EOR CONSTRAINT S (I - DOE NIPER - 527) CLASSIFICATION
EXPLANATION
Mobilit y Con trol
Gas ch anneling related to mo bili tv rathe r than heterogeneity; breakdown of polymer bank due to b acterial degr adation.
Operation s
Prob lems with oil treating, corro si on, sc ale, artificial lift, compression, formation plugging unrela ted t o i njectant quality.
Reservoir Co ndit ions
Refers to rese rvoi r flui d co ndit ions s uch as oil satura ti on, thi cknes s of oi l column , rese rvo ir dri ve mechanis m, etc. As defi ned, reservoi r con diti ons are a sub set of re servoi r description.
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Tech ni cal Con st rain ts CLASSIFICATION OF EOR CONSTRAINTS (I - DOE NIPER - 527) CLASSIFICATION
EXPLANATION
Reservoir Descrip tion
Refers to roc k relate d descrip tion such as depositiona l environment, rock c omposition, faulting, heterogeneity, continu ity, e tc.
Reservoir Heterog eneity
Area l or vertical permea bility variations, faults, directional flow trends, depositional environments, etc.
Process Design
Inadequate or inco mplete investigation of different area s known to b e important in the
EOR processes.
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Eff ect on Eff ic ienc ies of Various EOR Methods Method
Displacement Efficiency
Vertical Sweep Efficiency
Areal Sw eep Efficiency
Water Al ter nati ng Gas (WAG) Inject ion
Decrease s m obil ity of in jected gas Maintains r eservoi r pressure
Reduced recovery can re sult fro m gravity segregation
Improves areal conformance Reduces channeling
Seals reservoir conduits between injectors and
Seals reservoi r conduits between injectors and
producers Seals watered-out and high permeability zones
producers Seals watered-out and high permeability zones
MicrobialEOR
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N/A
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Con st rain ts fo r EOR Technologies Gas EOR Reservo ir h eterog eneity Mobil ity contr ol and re servoi r con confformance ormance Incomplete mixing Lack of pr edic ti ve capabili capa bil ittyy Poor injectivity Corro sion p robl ems wi th C O 2
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Con st rain ts fo r EOR Technologies Sur fact ant F lo od in g Reservo ir h eterog eneity Excessiv e chemical lo ss Cohere nce, stabil it y and c ost -eff ect ivene ss of surf acta nt sl sluugs gs Lim it ed t o r eserv oir sali nit y <20% NaCI eservoir Li mi ted to reservoi r tempera tu re<<200 temperature 200 o F Limi ted to perm eabil it y> 100 md Poly mer pr opaga ti on 8/12/2008
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Con st rain ts fo r EOR Technologies Alkaline Flooding Li mi ted range of appli appl iccabl abl e sali ni ty High c hemica hemic all con sump tio n Brine incompa tibil ity - precipitation
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Con st rain ts fo r EOR Technologies Reservoir Characterization The compl exity o f the rock and fluid di stri buti ons even in th e “ simplest ” reservoirs The inade quate a mou nt of detaile d inf orm ati on deta il ed from e ven the most a mbit iousl y sampled reservoir Scaling o f pr operties fro m co re or s malle r sc ale to interwe ll sca le Diff icul ties in i nte rpreting seismic data in te rms of ro ck a nd fl uid pr ope rti es 8/12/2008
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Con st rain ts fo r EOR Technologies Ther mal EOR Lower crude oil pr ice s due avit y,, sulfur du eto togr g ravity sulf ur and heavy m etal co nt ent Large fro nt end inv estm ents and delaye d r espo nses fr ont Absence of cost -effecti eff ecti ve technol ogy t o upg rade low -qua lit y, low -gravity c rud e int o saleable saleabl e pro duc ts Absence of cost effective technology that permits the use of l ow -grade fue l suc h as co al, pe tro leum coke, high sulf ur c rude oil and bra ckis ckishh wate waterr to to gene rate stea m w ith outt v viiol olating nvi ron mental it hou ati ng tthe he eenvi regulations 8/12/2008
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Tech ni cal Con st rain ts CL ASSIFI CA TION OF EOR CONSTRA INTS (I - DOE NIPER - 527) CLASSIFICATION Che mical Lo ss
Dow nhol e Comp letion
EXPLANATION Los s of injected fluid due to chemical, mechanica l, or mic robial degradation; chemical loss due to adsorp tion, ion exchange, or entrapm ent. Com pl etion t ech niqu es; e quipment; Productio n prob lems unrela ted to corro sion, sc ale , or artifi cial lift .
Facility Design
Surfa ce injection or prod uctio n facilities.
Gra vity Segregatio n
Gra vity overrid e in Ste am; po tential may exist fo r override in S itu or g as injection projects.
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Tech ni cal Con st rain ts CLASSIFICATION OF EOR CONSTRAINTS (I - DOE NIPER - 527) CLASSIFICATION
EXPLANATION
Injecti vity
Process sp ecif ic to gas injecti on proj ects. L ow poly mer inje c tivity in chemica l pro jects was co nsi dered inhe rent to the p olymer process..
Injecti on Contr ol
Fo rmation pressure parting; injecte d fl uid fl ow out of intended zo ne; inadequat e moni tori ng of injection.
Injec tant Qualit y
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Steam qualit y at s andface; inj ection well plugging relate d t o p oor mixing (polymer) or injectio n s ystem co ntam inants (rust, lub ricants). 55