SOCIETY OF PETROLEUM ENGINEERS OF AIME6?o0 North Central Expressway ~~ERSPE 5558DallP.:;, Texas 75206

THIS PRESENTATION IS SUBJECT Tt)CORRECTION

Review of Thermal Recovery Methods

By

Daniel N. Dietz, Member SPE-AIME, Delft University of Technology

@Copyright 1975American Institute of Mining, Metaiiurgicai, and Petroieum Engineers, Inc.

Th5.spaper was prepared for the 50th Annual Fall Meeting of the Society of PetroleumEngineers of AIME, to be held in Dallas, Texas, Sept. 28-Ott. 1, 1975. permission to c~PYis restricted to an abstract of not more than 300 words. Illustrationsmay not be copied.The abstract should contain conspicuous acknowledgmentof where and by whom the paper ispresented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGYor the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editorof the appropriate journal provided agreemer,tto give proper.credit is made.

Discussion of this paper is invited. Three copies of axIydiscussion should be sentt~ the Society of Petroleum Engineers office. Such discussions m8y be presented at theabcve meeting and, with the paper, may be considered for publication in one of the twoSPE magazines,

. -----4BSTRACT

Oil displacement ~s less than perfect minimize pressure later on. Heat stimulationof~ecausedespite driving forces - part of the prcducers is also used to facilitate start up.xiginal oil in place is retained by capillaryand by viscous forces. The viscous forces can be Where heat recuperation is applied, the re-reducedby heating the oil in place. Most of the covery-efficiencyof the heat should also be con-heat is inev~tably taken up by the oilsand, inter-sideredand an overall sweep from the reservoirbedded shales and cap- and base rock. The heat boundary may be preferred over a patternflood.is therefore used most efficientlywhere a maxi-mum of thermally recoverable oil is tied to a The heat may be applied from the surface byminimum of rock (heavy oil, high porosity etc.). specially designed hot water heaters or steamThe economy may be improved by recuperating heat generators. The injectors are subjected to highfrom swept formation for repeated use. therm??.stresses and in old fields, where more

often than not additional wells have to be drill,Besides reducing the,retaining forces, ther- edp the new ones are invariably used as injec-

mal drive alsc enhances the driving forces be- tors.cause many reservoir volumes of hot water, steamor air are required to displace one volume of oil,“ The compressed air for in situ combustionFor steam and air this enhancement is stronger requires more expensive surface installations,the lower the pressure. but less fuel than hot water or steam. Heat

recuperation is more efficient in combustionIn the initial phase, when the oil is still projects because it can be done continuously

cold, it may be hard to obtain satisfactorycir- by simultaneouscold wate; injection. Wet com-culation and specLal well patterns with a high bustion, with its double injection system re-number of producers per injector (inverted 9 SPOt,quires more engineering than any other thermal13 spot) are sometimes used. These patterns also drive: determination of optimum water/air ratiO#

evaluation of corrosion danger and where necessaThe bibliography of thermal drive up to 1970 has ry its prevention.been collected in SPE’reprint series 7 and 10.only more recent references are given individu-ally at end of paper.

2 REVIEW OF THERMAL RECOVERY METHODS SPE 5558

Thermal projects liberate additional reservesand their capitalized costs may be comparedwith the marketprice of proven primary re-serves.

INTRODUCTION

During conventionaldrives much oil maybe retained in the reservoir by capillaryand by viscous forces. In heavy oilfieldsup to some 20 % of the oil in place may beeconomically recoverableby conventionalmeans; some 20 % may be retain~ by capilla-ry forces (immobileresidual saturation);the other 60 % or more would be unproduciblebecause of its high viscosity.

Development of thermal drive was inspi-red by the wish to reduce the oil viscosityin place. A high temperature front is causedto sweep the formation. At this front theoil is heated and at its reduced viscositywill be displaced rcoreefficiently than whencold. Only the oil close to the front isfully heated; this hot oil drives less hotcil towards the producers. The amount ofheat actually spent on oil is patheticallysmall.

The heat exchange between the formationand its pore content is practically instan-taneous, the swept f~rmation is fully heated.In some longer periods of time, but withinthe life of a project, much heat is alsoabsorbed by interbedded shales and by capand base rock for considerable intervals.The swept formation and associated rock pre-sent the main burden of the heating process.It follows that economy is served by amaximum of thermally recoverable oil for aminimum of rock.

Maximum thermally recoverable oil isclosely related to maximum oil retained byviscous forces after conventional drives,in other words for reservoir oil of highviscosity.

F!inimumrock per unit oil will be found for:high porosity, high net sand percentage,thick oil bearing formation (relativelylesscap- and base rock).

Thermal drive is basically aimed at com-bating viscous forces. To some extent italso liberates oil trapped by capillary for-ces, because light fractions of this oilmay be distilled off. As explained above,heavy oils are the first choice and thesehave little distillable ends. In future,however, less heavy oils may also come intothe picture. Then there will be less oilwaiting to be liberated from viscous re-

taining forces, but this will be partly com-pensated by more light ends being distillablefrom capillary entrapment.

Temperatures in dry in situ combustionare generally higher than in other thermaldrives. In this process the distillation isenhanced by the cracking of part of theheavier components.

Thermal drive is a highly complex pro-cess involving many disciplines. Singleaspects, such as heat transport, have beenstudied scientifically. The scientific accu-racy of the results is reduced to an adequateengineers level when the simplifyingassump-tions concerning the other aspects are re-placed by the actual conditions.

Interactionof three phase flow andheat transport has been studied by computer,but these studies were usually confined toone or two dimensions.

Scaled experiments in sandbox models havebeen carried out in three dimensions. Onehas to know which combinations of effectscan be scaled simultaneouslyand which ofthese combinations is most relevant.

Coatst George,Chieh Chu and Marcum46)

recently carried out a sound investigation.They had the courage to develop a three di-mensional steamdrive computer programmer yetwere prudent enough to check results againstthose of scaled sandbox model experiments.Their approach may be indicativeof futurework: computer for regular evaluations,backed up by periodic spot checks by the moreexpensive scaled sandbox models.

HEAT SOURCES

The unit price of heat is important.Excessive heating would be wasteful. A ~Xi-

mum temperature of 100-300° C (210-570°F),evenly applied, should be adequate.

The temperature of hot water can be chosenat discretion. Steam temperature is governedby the reservoir pressure and happens to fallin an acceptable range.

In the case OS dry in situ combustion thetemperature follows primarily from the amountof fuel per unit formation. Temperatures mayrise to well over 1000° C(1800° F), whichis unnecessarilyhigh.

In wet combustion the temperature followsfrom a complicatedheat balance. It is essen-tially linked to the partial pressure ofsteam and is thus somewhat lower than in a pure

SPE 5558 DANIEL N. DIETZ 3

steam drive. This usually turns out to bea satisfactorytemperature.

HEAT RECUPERATION

In a straightforwardthermal drive mostof the heat is left behind in the swept for-mation, in the interbedded shales and incap- and base rock.

Purpose of heat recuperaticm is to pickup this heat, move it downstream and let somemore of it heat oil. This is repeated overand over again.

Heat recuperation is invariably carriedout by cold water injection. Hot water- orsteam injection has preceeded the cold waterinjection, so that a high temperature slughas been created. This slug is then moveddownstream by the cold water injection.We thus obtain a hot waterdrive for t?,eprice of cold water injection. Tha processis rather similar to a miscible slug drive.The temperature slug has a tendency to de-teriorate, even more than a miscible slug.The larger the temperature slug, the betterit stays intact and the higher the ultimaterecovery. On the other hand the longer onewaits before starting the heat recuperation,the more heat will be lost permanently incap- and base rock or will stay behind inthe residual temperature slug after the oilhas been swept.

It is the task of the reservoir engi-neer to predict production performance asa function of slug size (or heat injected).This can be done by calculations or bysandbox model experiments. This is not easy,but even more difficult is the selectionof the economic optimum slugsize, becausethis depends on thermal costs, oil priceand interest rate in the years after thedecision to switch over to cold injectionhas been carried out irrevocably.

Less heat is lost if a short tempera-ture slug can be made to travel throughthe formation. This requires cold waterinjection from a very early moment in theprocess. To maintain the short temperatureslug, heat has to be supplied continuously.This heat cannot be supplied by injection,becallsethe injection well is engaged incold water injection. It can be generatedinside the slug by in situ combustion.This process, wet combustion, works becausethe rate of oxidation happens to be suffi-ciently high at the moderate temperaturescorrespondingwith the presence of waterand a mixture of steam and air at reservoirpressure.

HEAT STIMULATION

Heat has not only been considered asa means to improve oildisplacement,butalso as a way to increase the productivityof heavy-oil wells. Productivity increasewas first attempted with bottom hole hea-ters. The heating facilitates lifting butdoes little to improve inflowperformance.Heat spreads into the formation by conduc-tion (rather slowly as soon as some distancehas to be covered), but the heat is transpor-ted back by convection,carried by the fluidflow into the wellbore. Thust the heat can-not penetrate very iar into the formationand sofar as it improves the fluid flow, itincreases the heat counterblow by convection,a self defeating effect.

It is more effective to interrupt pro-duction for a short while, transport heatinto the formation over a satisfactorydistance by convection through hot fluidinjection, store this heat in the rock andlet it there after be picked up again bythe producing fluids. Regrettably this sim-ple logic was not the product of clear thin-king but was acci~entally discovered aftera steamdrive test had to be discontinuedprematurely.

Steam is more suitable than hot water,because for a given amount of heat it intro-duces less water into the formation. As aresult, less water is produced back withthe oil, less heat is produced back withwater and more ‘isavailable to heat oil.

This process of cyclic steam injection,huff and puff, steam soak or steam stimula-tion (A beloved child has many names) hasfound wide application, some 250 000 bblldaynow being produced in this way. Tt is chea-per than steam drive, but does not yield ashigh an ultimate recovery, the oil beingdisplaced by the primary displacement mecha-nisms, though t? a further state of depletionthan would otherwise be economicallypossible.In some extreme cases it had made oil accumu-lations economically exploitable that wouldotherwise have been left undrilled. Wherethe primary drive has been exhausted, heatstimulation is equivalent to flogging theproverbial dead horse.

Following chapters discuss combinedapplicationsof thermal drive and thermalstimulation.

4 REVIEW OF T,H2RMAILRECOVERY NETHODS SPE 5558

RESERVOIR PERFORMANCE AND OPERATING POLICY exceed the lifting capacity of the well.The bottom hole pressure will increase and

Start up this will retard inflow from other direc-tions.

In the initial phase of a thermal driveproject an oil bank will develop. Its front In extra heavy oil reservoirs a sltu-end contains cold oil and when this oil of ation may develop where injectors and pro-high viscosity reaches the producers the ducers are linked in pairs, whilst the re-high inflow resistance of these producers maining bachelor-producersstay cold andcauses a high backpressure in the reservoir. produce little. See figure 1. To improveAs long as little comes out at the produ- this situation it is better to steam-cing end, little can be put in at the in- stimulate the laggard producers (if this wasjection end. In very heavy oilfields it not done beforehand) than to restrict themay be difficult or impossible to get a prolific ones.project going at a satisfac’b.oryrate. Wellpatterns with a high ratio of producers/ Heat bypassing from a drive stimulatesinjectors are in favour and some have been producers, but it may eventually lead tospecially designed for this purpose. steam bypassing and steam produced is steamSee table 1. that has not given off any heat. This may

seem wasteful, but a limited amount is per-Another way to start production at a missibJ.erbecause it still causes a dragging

satisfactoryrate is to steamsoak the pro- force, while it is somewhat cheaper than ~as-ducers beforehand. Repetition of the drive from a compressor plant.treatment may prove unnecessary,becauseafter a while sufficient heat from the In extra heavy oil reservoirs the sweep-drive may by-pass to keep the producers hot. efficiency may be below normal, but this

hardly reflects on the thermal costs per unitVertical distribution of the injection oil produced, as reservoir unswept is reser-

voir unheated. Only if the initial oil sa-In the case of steam drive gravity may turation was low - unlikely for extra heavy

cause preferential injection in the top part oil - one would first collect the oil in aof the reservoir. In a multilayered sand relatively small oilbank and then push thisthe lower part may not receive anY steam swept oil in a dead corner of the flowat all. Steam entry in a lower interval pattern.can be ensured by twin injection w~lls,completed on upper and lower interval re- Well pattern or flank drivespectively. Dual completion is in prin-ciple possible, but one may hesitate to We are concerned with sweep efficiencyadd this complication to the normal pro- of another kind when dealing with heat recu-blems of equiping a steam injection well. peration. At the end of a project the tem-

perature slug - or what is left of it -Similar considerations apply to Lhe stays behind and represents a loss of heat.

injection of other fluids. Thermal drive in a large reservoir <s usual-ly carried out in some regular well pattern.

Horizontal sweep efficiency Towards the end of the project temperatureslugs are scattered all over the field, in

Injectors and producers each have li- principle around all producers.mited capacities and both limits can intheir own way aggravate the effects of in- In the case of hot water or steam injec--stabilities. Normally each injector serves tion the travel time of the temperatureto drive oil towards several producers and front should be limited, lest the heat losseseach producer receives oil driven from seve- to cap- and base rock become excessive. Forral injectors. When the path between one minimum travel times one usually restrictsinjector and one producer becomes hot while distances to one location distance; thatother such paths are still cold, the resi- means selecting some type of pattern flood.stance along this particular path becomesless and oil will be displaced preferen- Wet combustion, however, does not suffertially along this path. Pressure in the from the limitation of travel time, becausesteamzone may drop and growth of the steam- the temperature slug can be maintained atzone in other directions will be retarded. minimum length (for minimum heat loss) all

the time. A general flank type drive wouldAt the producing end a generous hot end with a shorter front and a smaller

inflow from one direction may tend to temperature slug would be left behind. For

SPE 5558 DANIEL N. DIETZ5

wet combustion the alternative flank drive The pseudo mobility ratio serves as a toolmight be worth considering. to predict the stability of a proposed

project and to help in selecting the bestSTABILITY OF THERMAL DRIVE thermal drive for a particular reservoir.

Primary drive has a low recovery when Vertical sweep efficiency is largelythe displacement is unstable and this is determined by gravity overlay, determinedso for an unfavnu~diie mnhilj.tyrat~.o.Ther- by interplay between viscous and gravitymal drive was born from the wish to improve forces.mobility ratio’s. Indeed, these ratio’sare improved, but not to the point that In gaseous drives (steam, air) Varia-

they become smaller than one. Hot water, tion of pressure affects displacement insteam, air, or mixtures thereof are more several ways.mobile than hot oil. Yet some thermal At lower pressures:drives show stable displacement. Mobility a) volumetric velocities and thus pres-ratio is not a valid critnri.nnfor any and sure gradients in the displacingall displacement processes. fluid are higher,

b) steam temperature and consequentlyThe actual criterion for stability is <’iitemperature is lower and this

the ratio of pressure gradients in displa- ctiuseshigher pressure gradients incing and displaced fluid. In a conventio- tht}nil,nal drive the advance of the displacement c) gravity is almost constant and causesfront is determined by material balance, less overlay in the face of highera volume for volume displacement. The viscous forces,mobility ratio then is the reciprocal of d) heat consumption is less at the lowerthe pressure gradient ratio. In thermal temperature.drive this is not so. The displacementfront is the temperature front (definedby A systematic study of the influence ofsome isotherm) and its advance is deter- pressure has yet to be made. Present indi-mined by heat balance. The waste products cations are that - with:.na practical range -of the driving medium, cold water or cold lower pressure gives better performance.flue gas pass thrc~ughthis front ineffectively.

Steam soak operations, which allow pri-If we take heatlosses into account we mary depletion down to a lower pressure than

calculate some 4 pore volumes hot water would otherwise be possible, may thereforeto be required to move the temperature pave the way for an efficient thermal drive.front. This movement will displace some0.5 pore volume oil. Consequently the IGNITION OF IN SITU COMBUSTIONupstream hot water flow is 8 x strongerthan the downstream hot oilflow and the pres- All kinds of drastic measures have beensure gradient ratio is 8 x more favorable proposed (and mostly tested with spectacularthan the reciprocal of the mobility ratio. results) until it was discovered that upon

air injection some oxidation occurs even atIf we wish to adhere to some sort of original reservoir temperature. This will

mobility ratio as stability criterion, we cause a slow temperature rise. At increasingshould define a pseudo mobility ratio, which temperature the reaction rate will increaseis the usual one divided by the velocity and so will the rate at which the temperatureratio of driving and driven fluid. rises. As a rule spontaneous ignition deve-

lops in a couple of months.Similarly we can calculate that hardly

more than 1 % of the steam serves to dis- Very mild preheating by hot water orplace oil, the bulk of it falls flat on its steam injection reduces ignition time toface at the condensation front and - as far about one day.as oildisplacement is concerned - it sneaksoff uselessly as cold condensate through REVERSE COMBUSTIONsome narrow bypass channel.

Reverse combustion combines thermalTable 2 presents some typical figures drive with a maximum of heat stimulation.

but for actual projects the individual It ensures that oil once mobilized does notfactor will have to be calculated. ‘freeze’ again and plug a cold part of the

formation.

6 REVIEW OF THERMAL RECOVERY METHODS SPE 5558

The principle works in the laboratory severest conditions at the producing end:and in short-spacingfield pilots, but sel- .h;gh gas rates, extreme acidity, oxygendom in commercial operations because spon- breakthrough, high temperatures.taneous ignition around the injectors cutsoff oxygen supply. The Athabasca Tarsand The heat soak was invented (discovered)is probably the only known exception. in 1959 to treat wells where the prcduc-Here, spontaneous ignition will take seve- tion was too cold to our taste. What tookral years, mainly because of the low initi- us so long thereafter to invent the coldal temperature. water soak 64) if the production should be

too hot to our liking? And why did not weEQUIPMENT do more with chemical soak 59J60) when the

production was unpleasantly corrosive?Surface installations

Wet combustion is a much milder process.High pressure waterheaters and steam What corrosion hazards remain are predic-

boilers used to be considered delicate in- table and can be designed against by choicestruments needing meticulously purified of the injection water,if necessary withfeedwater. When they came to the oilfields additives.in special designs they learned to live oncoarser fare. Yet some fields have elabo- Production stationsrate water purification pl,ants. In othersthe treatment may be simple or non existant. The treatment of thermal oil may offer

special problems in the breaking of varyingGas driven engine-compressorunits are types of emulsion.

generally used to supply the air for under-ground cotiustion. In populated area’s the malodiferous

gas from combustion projects may requireSeveral studies have compared the some treatment before it can be vented.

costs of heat injected with the costs of Disposal of the produced water may requireheat generated in situ, disregarding pos- similar attention.sible differences in effectivenessof theheat. Compressors require more capital but ECONOMIC EVALUATIONless fuel than boilers. The recent sharpincrease in fuel prices has caused a shift Injection costs can be evaluated sepa-in favour of compressors. rately and should not vary too much from

one field to another. They can be expres-Injection wells ‘sealas unit costs (capitalplus operating)

of cold water, hot water, steam, compressedMechanical problems of hot injection air. When in doubt, imagine a contractor

wells are mainly related to the thermal delivering it at the wellhead.stresses in cemented casing. Failureshave occurred by stripping after cooling. The operation of producing wells and

the handling of oil in thermal drive areMore than superficial heat insulation very much like they are in primar.?pro-

of the tubing may not be paid for in terms duction. There will be some additionalof prevented heat loss, but is sometimes costs per well, but the wells being morestill considered worthwhile to protect the prolific, the production costs per bbl oilcasing against extreme temperatures. should be roughly the same.

The corrosion hazard of simultaneous The injection creates an additionalair- and waterinjection for wet combustion reserve amd it is therefore convenient tocan be bypassed by alternating dry air and estimate or to report the capitalized in-oxygenfree water and by using inhibitor jection costs per unit extra producible oil.when switching over. This u?.itprice of a reserve may usefully

be compared with the market price of primaryWhere old fields require infill drilling reserves.

the new wells will be used as injectors.Injection per unit extra oil is there-

Producing wells fore a key figue. Table 3 represents somerepresentativevalues from field experience.

Of the several thermal drives the drycombustion is the one that offers the It all boils down to the question whether

SPE 5558 DANIEL N. DIETZ 7

L.

it is cheaper to revive a dead lease or to (10) Satter, A., and Parrish, D. R.:”A two-buy another one with primary reserves. dimensional analysis of reservoir hea-

ting by steam injection”,SPEJ (June 1971CONCLUSIONS 185-197.

(11) Patterson, M. M., Murphey, C. E. Jr.,1) Thermal drive serves primarily to re- and Sheffield, B. C.:”A magnetic device

duue viscous retaining forces, but it to detect tension failures in oilfieldalso intensifies driving forces. The casing”, JPT (August 1971) 905-910.combination leads to a newly defined (12) Niko, H., and Troost, P. J. P. M.:’’Expe-pseudo mobility ratio, a quantitative rimental investigationof steam soakingyardstick for dis~>lacementstability. in a depletion-type reservoir”, JPT

2) Essentially very little heat is re- (August 1971) 1OO6-1014.quired to raise the temperature of the (13) Yoelin, S. D.:“The TM Sand steam-stimula-oil right at the displacement front. tion project”, JPT (August 1971)987-994.There is a large scope for heat recupe- (14) E1-Saleh, M. M., and Farouq Ali, S. M.:ration. “Oil recovery by a water driven steam

3) Choice of well pattern is governed by slug”, SPEJ (December 1971) 351-355.start up requirements, sweep efficiency (15) Volek, c. W., and Pryor, J. A.:’’Steamof oil displacement and sweep efficiency distillation drive - Brea Field, Califor-of heat scavenging. nia”, JPT (August 1972) 899-906.

4) Thermal costs of extra oil are direct- (16) Gottfried, B. S.:’’optimizationof aIy comparable with the price of primary cyclic steam injection process usingreserves. penalty functions”,SPEJ(February 1972)

13-20.ACKNOtiEDGEMENT (17) Farouq Ali, S. M.:”A current appraisal

of in-situ combustion field tests”,The review has been made possible by JPT (April 1972) 477-486.

the publication of the 421 papers indi- (18) Burger, J. G., and Sahuquet, B. C.:cated directly or indirectly in the list “Chemical aspects of in-situ combustion cof references. Heat of combustion and kinetics”, SPEJ

(October 1972) 410-422.REFERENCES (19) Hardy, w. C., Fletcher, P. B., Shepard,

J. C., Dittman, E. W., and Zadow, D. W.:(1) Thermal recovery processes. SPE reprint “In-situ combustion in a thin reservoir

series Nr. 7. containing high-gravity oil”, JPT(2) Thermal recovery tech +q~ s SPE re- (February 1972) 199-208.

print seri?s Nr. 10. (20) Martinr W. L., Alexander, J. D., Dew, J.(3) Combarnous, M. A.; “Combined free and and Tynan8 J. W.:’’Thermalrecovery at

forced convection in porous media”, North Tisdale Field Wyoming”, JPTSPEJ (Dec. 1971) 399-405. (May 1972) 606-616.

(4) Alikhan, A. A., and Farouq Ali.,S. M.: (21) Hearn, C. L.:”The El Dorado steam drive-“Oil recovery by hydrocarbon slugs driven A pilot tertiary recovery tesk”r JPTby a hot water bank” , SPEJ (Dec. 1971) (November 1972) 1377-1384.342-350. (22) P~checo, E. F., and Farouq Ali, S. M.:

(5) Gates, C. F., and Sklar, I.:’’Combustion “Wellbore heat losses and pressure dropas a primary recovery process - Midway in steam injection’:,JPT (February 1972)Sunset Field”, JPT (August 1971)981-986. 139-144.

(6) W-I, C.H. and Fulton, P. F.: “Experi- (23) Boberg, T. C., and.West, R. C.:’’Correla-mental simulation of the zones prece- tion of steam stimulationperformance”ding the combustion front of an in-situ (Forum)JPT (November 1972)1367-1368.combustion process”, SPEJ (March 1971) (24) Schutler, N. D., and Boberg, T. C.:38-46. “A one-dimensionalanalytical technique

(7) CaSey, T. J.: “A fieldtest of the in- fer predicting oil recovery by steam-situ combustionprocess in a near- floading”, SPEJ(December 1972) 489-498.depleted water drive reservoir”, JPT (25) Weinstein, H. G.:”A semi-analytic metho(February 1971) 153-160. for thermal coupling of reservoir and

(8) Chu, C.: “Kinetics of methane oxidation overburden”, SPEJ(October 1972)439-447.inside sandstone matrices”, SPEJ(June 1971 (26) Craig, F. F. Jr.:’’TheTulsa meeting in145-151. retrospect - ?u’Iinterview with program

(9) Johnson, F. S., Walker, C. J., and chairman Craig”, JPT(June 1972)686-689.Bayazeedt A. F.:’’Oilvaporizationduring (27) Anand, J.,and Somerton, W. H.:’’Predic-steamflooding”,JPT (June 1971) 731-742. ting thermal cmductivities of forma-

tions from other known properties”,SPEJ (October 1973) 267-273.

—

8 REVIEW OF THERMAL RECOVERY METHODS SPE 5558

(28) Chase, C. A., and o’Ds1l,P. M.: “Appli- (44) Boxton, T. S., and Pollock, C. B.:cation of variationalprinciples to “The Sloss COFCAW project - Furthercap and base rock heat losses”, SPEJ evaluation of performance during and(August 1973) 200-210. after air injection”, JPT(December 1974)

(29) Boberg, T. C., Penberthy, W. L. Jr.,and 1439-1448.Hagedorn, A. R.:’’Calculatingthe steam- (45) Afoejw B. I.:“Conversionof steam invstimulated performance of gas-lifted jection to waterflood, East Cosli.ngaand flowing heavy-oil wells”, JPT Field”, JPT (November 1974)1227-1232.(October 1973) 1207-1215. (46) Coats, K. H., Georgeg W.D., Chu, C., and

(30) Buchwald, R. W. Jr., Hardyr W. C., and Marcum, B. E.:’’Three-dimensionalsimu-Neinast, G. S.:’’Casehistories of three lation of steamflooding”,SPEJin-situ combustion projects”, JPT (December 1974) 573-592.(July 1973)784-792. (47) Somerton, W.H., Keese, J.A. and Chu, S.I&

(31) Hall, A. L., and Bowman, R. W,:’’opera- “Thermalbehavior of unconsolidatedoiltion and performance of the Slocum sands” SPEJ (October 1974) 513-521.thermal recovery project”, JPT(April 1973) (48) Penberthy, W.L.Jr.:’’Silicatefoamwell-402-.408. bore insulation”JPT (June 1974)583-588.

(32) Smith, R.V., Bertuzzi, A. F’.,Temple- (49) Sawyer, D.N., Cobb, W.M., Stalkup, F.I.ton, E. E., and R. L. ClamPitt:’’Recovery and Braun, P.H.: “Factorial designof oil by steam injection in the Smack- @nalYSiS of wet-combustion driVe.SPEJovex Field, Arkansas”, JPT(August 1973) (February1974) 25-34.883-889. (50) Terwilliger, P.L., Clay, R.R., Wilson,

(33) Baker, P. E.:’’Effectof pressure and rate L.A.Jr. and Gonzalez-Gerth,E.:on steam zone development in steamfloo- “Firefloodof the P2-3 Sand reservoir in

ding”, SPEJ(October 1973)274-284. the Miga Field of Eastern Venezuela”(34) Prats, M., and Miller, W. C.:’’Therole JPT(January 1975) 9-14.

of technical publications in the ad- (51) Prats, M. and O’Brien, S.M.:’’Thethermalvancement of fluid injectionprocesses conductivity and diffusivity of Greenfor oil recovery”, JPT(December 1973) River oil shales” JPT(January 1975)1361-1370. 97-106.

(35) Burger, J. G., and Sahuquet, B. C.:’’Labo- (52) Bradley, B.W. and Gatzke, L.K.: “Steam-ratory research on wet combustion”, flood heater scale and corrosion”JPT(October 1973) 1137-1146. JPT(February 1975) 171-178.

(36) Somertow, W. H., Keese, J. A., and Chu, (53) Gates, C.F. and Brewer, S.W.: “SteamS. L.:“Thermalbehaviour of unconsoli- injection into the D and E zone, Tularedated oil sands”, SPEJ(October 1974)513-521, formation, South Belridge Field, Kern

(37) Weinstein, H. G.’:”Extended semianalytic County, California” JPT(March 1975)method for increasing and decreasing 343-348.boundary temperatures”,SPEJ(April 1974) (54) Merriam, R., Wechsler, A., Doorman, R.152-164. and Davies, B.: “Insulatedhot oil-pro-

(38) Parrish, D. R., Pollock, C. B., and ducing wells in permafrost” JPT(MarchCraig, F. F. Jr.:“Evaluationof COFCAW 1975)357-36!5.as a tertiary recovery method, Sloss (55) RiVerO, R.T. and Heintz, R.C.: “Re-Field, Nebraska”, JPT(June 1974)676-686. steaming time determination - Case

(39) Craig, F. F. Jr., and Parrish, D. R.: history of a steam-soakwell in Midway“A multipilot evaluation of the COFCAW Sunset” JPT(June 1975)665-671.process”, JPT (June 1974) 659-666. (56) ChU, C. and Trimble, A.E.: “Ntunerical

(40) Parrish, D. R., Pollock, C. B., Ness, N.L., simulation of steam displacement - Fieldand Craig, F. F. Jr.;”A tertiary COFCAW performance applications”JPT(June 1975)pilot test in the Sloss Field, Nebraska”, 765-776.JPT (June 1974) 667-675. (57) Smith, R.C. and Steffenson, R.J.: “Inter-

(41) Garon, A. M., and Wygal, R. J. Jr.:”A pretation of temperattlreprofiles inlaboratory investigationof fire-water Water-inj@CtiOnWells” JPT(June 1975)flooding”, SPEJ (December1974)537-544. 777-784.

(42) Dabbous, M. K., and Fulton, P. F.: (58) Hoist, P.H. and Karra, P.S.: “The size of“Low-temperature-oxidationreaction ki- the Steam zcne in wet cmbustion” SPEJnetics and effects on the in-situ com- (February1975) 13-18.bustion process”, SPEJ (June 1974)253-262. (59) Kerver, J.K. and Hanson, H.R.: ‘sCorrosion

(43) Merrill, L. S. Jr., Kazemi, H., and inhibitor squeeze technique - FieldGogarty, W. B.:’’Pressurefall off analy- evaluation of engineered squeezes” JPTsis in reservoirs with fluid banks”, (January1965) 50-57.JPT (JufiJ1974) 809-818. (59a)Junkin, E.D.Jr.: “Discussion”JPT

(43a) Dowdle, W. L.:“Discussion”,JPT(JuIY 1974) (January 1965) 57-58.818.

SPE 5558 DANIEL N. DIETZ 9

(60) Vetter, O.J.: “The chemical squeezeprocess - Some new information on someold misconceptions”JPT (March 1973)339-353.

(61) SPE “Symposiumon Improved oil recovery”

April 22-Z4, 1974.(62) Proc. 8th WPC, Vol. 3.(63) Proc. 9th WPC.(64) DietzV D.N.: “Cold water soak”

(March 1973), Neth. Patent Appl. 7303779.

TABLE 1 - MATCHING PRODUCTIVITY TO INJECTIVITY

Well pattern Producers Der in.!ector

5 spot 1

inverted 7’spot 2

inverted 9 spot 3

inverted 13 spot 5

TABLE 2 - CONVERSION OF MOBILITY RATIO TO PSEUDO M3BIL1TYRATIO - SOME TYPICAL FIGURES

Drive Divide bypseudo factor

Hot water 8

Steam 80

Dry combustion 60

Wet combustion > 80

TABLE 3 - INJECTION PER UNIT THERlW4LOIL - REPRESENTATIVEFIELD FIGURES

Drive

Hot water 9 m3/m3 (bbl/bbl), 1.4 ton ‘/bblSteam 1.66-6.29 ton/m3 (bbl waterequivalent/bbl),

0.26-1 ton/bblDry combustionWet combustion 3000 sm3’m34 ‘xsMcf’bbl1TO-1OOO sm /m , I-6 Mscf/bblSteem soak (though not a drive really) 0.16-2 ton/m3, 0.025-0.32 ton/bbl

x) metric ton = 2200 lbs

~: An extreme ‘economic limit’ can be defined, where as much fuel isconsumed in surface installations as is produced from the reservoir.With this concept one can easily determine net fuel gain fraction.Zero net fuel gain figures are approximately:

Hot water i’5m3/m3 (bbl/bbl). 12 ton/bblSteam 25 ton/m3 (bbl waterequivalent/bbl), 4 ton/bblCombustion 20 000 sm3/m3, 110 sMci?/bbl

AA

a b

Fig. I - Tendency for hot channels tomonopol ize one injector and one pro-ducer in a steamdrive project, a)upper zone, b) lower zone.

Courtesy Shell International Petroleum Maatschappij.Adapted from ref. 2 page 12g.