A Study of the Mechanisms of Carbon Dioxide Flooding and Applications to More Efficient EOR Projects

8/19/2019 A Study of the Mechanisms of Carbon Dioxide Flooding and Applications to More Efficient EOR Projects

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A Study of the Mechanisms of Carbon Dioxide Flooding And

2

Adioetions to More Efficient EOR Proieots

SPE20

, .

pressure limitation could be overcome, then an appreciable the gas-oil ratio has begun to climb to very high values

amount of recoverable oil could be added to our reserves. Also, it maybe observed that the slope of the enhanced oi

recovery versus pore volumes of gas i@3cted changes a

CONDITIONALLY MISCIBLE FLOODS

approximately 0.4 pore volumes iqjected. Furthermore, a

this same instent, the gas-oil ratio increases from S6

SCF/bbl [98 xn3/m’1,the original gas-d ratio, to about 700

A great number of reservoirs do not possess the reservoir

SCF/bbl [125 ms/m31.

pressure sufllcient to promote either a carbon dioxide FCM

or a MCM flood. As C02 is tiected into one of these

AU of these fmdinga would indicate that neither fmt-

reaervoire, the gas mixes with the reservoir fluid and forms

contact miscibility nor multicontact miscibility would b

a gaa and a liquid phase. These phases progress through

the reservoir until a production well is reached. The

achieved at 2,500 psia [17.23 MPal. But Figurv 2 show

that there is a zone of constant composition which i

composition of these two phases, under

immiscible

progressing through the reservoir, brought on by thi

conditions, is shown in Figure 1 as a fimction of the

distance along a CO, flood. TMs figure result.a from a

irnm&4ble displacement, It could be considered that thi

zone of constant composition is a bank of solvent seeking

simulation of a slim tube COZflood injecting pure carbon

dioxide into a tube saturated with a live reservoir fluid, “B”

to achieve conditions of -lbfity, but not quite achieving

it because of the dommant quantity of methane, nitrogen

Field, The temperature of the reservoir was 164°F [346.5

etc., that overwhelms it.

K] and the pressure, 2600 psia [17.24 MPal. The MMP

for pure CO. aud thk fluid had been experimentally

established as 3340 psia [29.0 MPal. Thus the flood is

COMPOSITION OF SLUG TO ACHIE

VE

MISCIBILITY

highly immiscible - some 640 Psia [5.79 ~a] or 25 Percent

below the MMP. The flood had progressed approximately The critical compositions in the premixed transition zon

40 percent of the way from the injection to the production

can be determined experimentally from the composition o

well. the in-situ resenoir gas and liquid hydrocarbons forme

during a slim tube flood. Such a flood would be conducte

Not all of the components are shown, as to do so would

using pure carbon dioxide. The concentration of th

greatly and unnecessarily clutter the graph, Instead,

Figure

1 shows the compositional changes for methane, carbon

reservoir hydrocarbons that are removed by the carbo

dioxide flood were determined from the composition of th

dioxide, butanes, end a typical fraction (C, - C,,) of the

heavier portion of the reservoir fluid. Aa maybe observed,

gaseous hydrocarbon stream.

the composition of the gas phase, shown by the triangles,

Also, the critical composition may be determined b

does not equal the composition of the liquid phase, shown

conducting

simulated floods.

The experimenta

by the circles, that exists at the same spot along the flood’s

determination, howeve~, would be very difl%xdt, involvin

path,

a slim tube having a roll-pressure microsampier affixed

However, it is instructive to obseme the composition of the

the tube’s exit before the back pressure regulator

Therefore, the investigation was pursued using

gas at the gas-liquid front as a function of time, as shown

in Figure 2. In thw instance the composition of the

commercially available multicomponent reservoir simulator

components *g up the gas phase at the gas-liquid front

Four reservoir fluids nf different composition were chose

appears to approach a constant as the flood progresses. In for this study. Theso fields are typical of those reservoir

this case the COZ is reduced from 100 percent to 0.45

that have been waterflooded to their economic limit, tm

percent end the intermediate C,-C,, portion rises from 0.0

to 0.02 percent.

yet contain appreciable amounts of original oil in place.

complete analysis of each of these live reservoir fluids

given in Table

Methane contents range from 18

The interracial tension, calculated using the Macleod-

percent to 61.5 percent.

The heptane plus, the ~

Sugden correlation and psrachors for the individual

fraction, has been divided into three ranges of pseud

components of the mixture, is presented in

Figure 3. This

figure dcpicta the interracial tension between the gas and

compounds, CT to Cll, C,z to C=, -d Cu+. The Mferenc

liquid hy*bon phases as a function of distance along

in the character of these fluids w best indicated by. th

molecular weight and gravity of the CT+ fracbon

the slim tube. The front has progressed about 6% feet [1.7

MolecuIar weights of the stock tank oils range horn 184

ml.

The gas-oil interfacia.1 tension, originally at 11.4 248 and heir gravities from 30.4 to 45.0.

dynes/cm [11,4 N/ml has been reduced at this point to 2.6

dynesJcm [2,6 N/ml.

Several authors report that as

miscibility is approached, the interracial tension (IFT) drops

PRESENT

ATION OF

DATA AND RESUL~

to an exceedingly low value. More importantly, whenever

the IFT drops below, say 0.1 dynes/cm [0.1 N/ml, the

A series of slim tube simulations was performed using

residual oii ett behind by a gas displacement is drastically four of the chosen reservoir fluids whose characteristics a

reduced -

approaching values less than one percent.$oo

given in

Table 1.

Simulations of a pure COa flood

Thus, at these extremely low interfaciel tensions the

several chosen reservoir pressures were run. These serv

recovery would be expected to be nearly complete.

two purposes first, to determine the recovery afforded

Contrariwise, as can be seen by reference to

Figure 3,

the

COZ at the pressurq aud second, to determine t

interracial tension ‘remaim relatively high and thus the

composition of the Cz+solvent formed by the displacemen

recovery due tm gas displacement would be expected to be

low.

SLIM WE SIMULA

TION

Figure

4 presente the enhanced oil recovery and the gas-

oil ratio as a function of the pore volume of pure C02

The slim tube was assumed to be 40 feet [12.2 ml long,

injected. Two items of interest are presented in thii

figure. F@L the oil recovery reaches only 0.68 by the time

inch [0.64 cm] diameter, and packed with sand having

porosity of 0.379 and a permeabfity of 3000 md [2.96 @l

.-.


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SPE20190

S. Haynes and R. B. Alston

3

The pore volume of the dim tube wee 146.34 cd. Gas, or

As with the “B’

Field case, the light ends increase as the

solvent, was injected at 17,2 crna/hr (at reeenroir

operating pressure decreases end the amounts of the

conditions).

heavier components decrease. Tim butanes reti f~h’

constant over the pressure ranges studied.

Jt~mE

B

Although each of the reservoir fluids wee investigated RESULTS USING THE ETHANE PLUS SO VE~

during these studies, specifkally we present the results

using reservoir fluids “B” end “F. The equation-of-state

Additional simulations were then made using the Cz,

parameters needed for the simulations were carefully fitted

to experimental PVT date using en awdliary program.e

portion of the equilibrium reserwoir gas, The solvent was

Using thesa EOS parameters, the composition of the

calculated on the basis of a theoretical 100 percent split

between the methane and ethsne component It was

resemoir fluid wee adjusted to be the bubble point liquid

thought that the error introduced by this assumption would

for the desired pressure. Carbon dioxide was continuously not substantially alter the results of the simulations. Again

iqjected at the reservoir temperature and the studied

we focus on two of the four fields, namely “B”and “F.

reservoir pressure.

“B”Field Reservoir

“B”Field Reservoir Fluid

Four additional slim tube experiments were then made

In the fol.Iowing example, the “BWfield

reservoir

fluid,

having the composition shown in Table 2, was used in a

using the same resmvoir fluid as that described in

TubZe1,

except that ita composition was the bubbIe-point fluid at

slim tube simulation. These compositions were obtained by

flashing the 3340 psia bubble point resmwoir fluid to the

the investigated pressure. A 13 percent pore volume slug

desired operating pressure.

Carbon dioxide was

of solvent was injected into the tube followed by injection

of pure COZ, (The composition of the solvent used in these

continuously iqjected at 164‘F [346.5 KI and 3260, 3000,

latter investigations consisted of the C*, fmction of the gas

2760,2500, or 2000 peia [22.4, 20.7, 19.0, 17.2, or 13.8Ml%

respectively]. C ompoeitione of the equilibrium gas and

phase SEgiven in Table 3.) The results of these additional

liquid phase in the slim tube were obtained from the

simulations are given in

Tab

6.

simulation, Aa mentioned earlier, the composition of the The enhanced oil

recove~

end the gas-oil ratios obtained

gas phase at the ges/liquid front becmne constant after a

short-period of COZiqjection. We felt that the Cg, portion

using a slug of ethane plus solvent at 2500 @a [17.2 MPal

are plotted in Figure 7 as a function of the gee ir@cted.

of thw gas phase should be miscible with the reservoir

Two important differences between these curves ad those

fluid. To test this hypothesis, C,+ solvents were calculated

for the equilibrium gases obtained at each pressure. The

reported in lSgum 4 are evident. FirstA the slope of the

recovety curve versus pore volumes b&xted is constant

resultant values are reported in

TdJle

3.

until the final gas breakthrough at about 0.9 pore volumes

It will be noted that the amount of light ends, CZ-C3,

iqjected, Also, there is no prehninary break in the GOR

versus pore volume ~ected cwe until this same final gas

increases es the operating pressure decreasea, whereas the

breakthrough.

amount of the heavier components (CS - CJ decreases.

Only the butane quantity remains f&ly constant over the Other phenomena may be observed as s results of

pressure range of 2000 to 3250 psia [13.8 ta 22.4 ma].

simulating thh 2500 psia [17.2 MPal flood. Referring h

Figure 8, one can see that the intarfaciel tension between

the gas and oil phaees is essentially zero

near the gas-oil

“lVField Reservoir Fluid

fron~ furthermore, this low interracial tension progresses

A similar simulation was performed

on

the reservoir fluid

without diminution in value during the entire time that the

flood is in progress, i.e., even up to the time the gas-oil

obtained from F“ field. The composition of the fluid is

fkont breaks through to the production end of the slim

given in Tab 4, Slim tube simulations using this fluid

tube. This low interracial tension indicates that the flood

were made at 2500,2000 and 1750 psia [17.2, 13.8, and 12.1

is a miscible flood.

Ml% respectively]. The experimental MMP for the fluid

was determined to be 2800 psia [19.3 MPal. Figure 5

Further evidence of this rniacibtity may be discerned from

shows the enhanced oil recovery and the gas-oil ratio

the compositions obsewed throughout the flood. ZO@m 9

obtained fkom sim~ting a pure C02 flood at 1750 psia

[12.1 MPal. In tlue case, some 1050 psia or

40

percent

presents the changes in the composition of the gas and oil

below the MMP, the performance is typical of an

phases accompanying the 2500 psia [17.2 MPal flood

immiscible flood - that is, low recovery, 0.58, end early gas

performed using the selected ethene PIUSsolvent. The

triangles represent the amounts of the various components

breakthrough, at PV equals 0.4. present in the gas phase, and the circle% those present in

the liquid phase. At the particular instant these

Selectkd composition of the gas and liquid phaeea ie given

components are recorded, the flood front had progressed

in Figure 6. As was found in the simulation using the “B”

field reservoir fluids, the gee and liquid composition do not

approximately 40 percent along the * tube, There are

several significant events shown

that

should be pointed outi

equal each other at any point in the flood. Thii is typical

of an

immiscible flood. Gas phases determined at the 20-

0

The gas phase abruptly ceased to exist beyond

foot [6.1 ml distance are given in

Table

5. Again, since the

40 percent of the elim tube length. From

dominant componen~ wee methane, whereas the developing

that point on only liquid reservoir fluid exists.

in-situ solvent of interest would

contain the

heavier

The composition representing the individual

components, en ethane plus gaseous solvent is also reported

components msking up these pha8es also

in the table.

indicatea the abrupt change.

.—


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; . ; .

.

SbE20190

S, Haynes and R. B. Alston

5

—

does not have an intermediate change in value as would

immiscible flood, as discussed earlier. Both

passing, all of which would pobnt~y

accompany an

decrease the chances of a high

of these Iota indicate that the flood did progress as a

8

recovery.

miscible od It should be notad that just one instant

before the fti gas breakthrough, the GOR appeared to

rise very slightly. Perhaps this may indicate that this slug

0

A

study of slug size was made using the “B”

size, 6.6 percent HCPV, is approaching the minimum

field reservoir fluid. The floods proved ta be

requirement, Further investigation would be necessary to miacibbx however, there was an indication

establish this point.

that a 6.5 percent pore volume slug may be

approaching the minimum required to

The interfiicial tension between the gas and liquid phases,

maintain miscibility throughout the simulated

as determined by the simulation progranw is presented in

slim tube flood.

Figure

13. Four separate curves are shown here, that at

the instmt when approximately 26, 50, 76, and 100 percent

of the slim tube had been traversed by the flood. During

each of these instants, the interracial tension was low.

Other investigators reported that oil recoveries approaching ACKNOWL

EDGEME~

those obtained by miscible floods are achieved when

interracial tensiona are this low. The present simulations

The authors are indebted ta numerous researchers who

certainly tend to corroborate this finding.

developed the data presented in this paper. We appreciate

the careful review of the paper and suggestions given by

Drs, Marc F, Fontaine and Mary K. Hill. The presentation

CON

CLUS IONS

of this payer would not have been possible without the

encouragement,

The following conclusions may be drawn es a result of this

suggestiona, and pertilon of the

investigatiorx

management of Texaco Inc., to whom we are gratefti.

0

Carbon dioxide floods simulated twing pure

REFER

ENCES

COt at pressures below the MMP yielded low

enhanced oil recoveries, early gas

breakthroughs, and interfaced tension greater

1.

Alston, R, B., Kokolis, G. P., and James, C.

F.: “C02

than one (1) dyne/cm [1.0 N/ml. AUof these

Minimum Miscibility Pressure A correlation for

phenomena

“indicate the floods were

Impure CO, Streams and Live Oil Systeme~ SPE

immiscible.

11959 presented at the 1983 Annual Technical

Conference and Exhibition, San Francisco, Oct. 5.8.

0

During these

immiscible” tloode, it was

apparent that at the gas-liquid flood front the

2,

Brown, A, Haynea, S., Alves, G.W., and Lii, F.H,:

gas phm compositions were approaching a

“Carbon Dioxide Floodiig with a Premixed Transition

constant value, These compositions appeared

to be unique and dependent upon the

zone of Carbon Dioxide and Crude

Oil

Componen@’

U.S. Patent No.4,589,486 (1984).

reservoir pressure and characterization of the

resexwoir fluid, 3, Cardenas, R. L,, Alston, R. B., and Nute, A J.:

“Laboratory Design of a Gravity Stable Miscible CO,

o

Slugs of ethane plus solvents, the

Procesa~ J. Pet. Tech, (January 1984) 111-118.

compositions of which were determined from

the above pseudo steady-state operations,

4.

Slobod, R,L. and Koch, H.A.: ‘High-Pressure Gas

followed by continuous injection of COZwere

Iqjection - Mechanism of Recovery Increase: Drill.

then used in the simulation studies to

end Prod, Prac,, API (1953) 82-96.

displace the respective reservoir fluids. The

oil recoveries, the GOR accompanying the

5.

Wagner, 0. R. and Leach, R. O.: “Effect of Interracial

flood, and the intafacial tension indicate that

Tension on Displacement EfEciencyS Sot. Pet. Eng.

these solvent-enhanced floods

were

miscible

J. (December 1966) 335-344,

at pressures up to as much as 40 percent

below the MMP required for displacements

6.

Hough, E.W. and Warren, H. G.: “Correlation of

with pure COZ.

Interracial Tension of Hydrocarbons Sot. Pet. Eng.

J, (December 1966) 345-349.

0

A comparison was made of the Ct+ solvent’s

effectiveness with that ofa more conventional

7.

Ahmed, T, H,: “An Experimental Study of Crude Od

LPG solvent. The results were SEfollows

Recovery by High Pressure Nitrogen Iqjection: PhD

Thesis, University of Oklahoma, Norman,

OK

(1980).

L

In the case of the LPG solvent, the

flood produced a slightl earlier C02

8.

J

Coata, K. H.: “An Equation of State Composition

breakthrough

than

it di with. the C2+

Model; SOC.Pet, Eng. J. (October 1980) 363-376.

solvent. The ultimate recoveries were

essentially the same.

9.

Coats,

ICH. and Snuu% G.T.: “Application of a

Regreseion-Baaed EOS PVT Program to Laboratmy

2.

Lack of fmt contact miscibility of C02

Da@” paper SPE 11197 presented at the 57th

in the LPG slug would increase the

Annual Fall Technical Cotierence and ExMbition,

chances of f~ering and solvent by

New

Orleansj eptember

22-29, 1982.

---

9


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SPE 20190

9

Tabk

RESERVOIR FLUIDS

x1361dmaJwl

omt37

OLVJ17

0.0043

00035 0.0203 0.M21

o.4m4 0.3172

0.1423

0.0441

0.2267 O.lms

0.0119 0.0422

00441

0.0249 0.0597

O.oa

O.lEW 0.1s47 0.1652

0.1s16 0.1226

0.207s

0.0747 0.042s

O.osn

T2W42

RE22RVDIR FLUID FRDM W FIELD

Mb

.a23Q

m

J?zw

JMQ

E52kl

0.027 3

0.-

0.5146

0.1410

0.0437

00607

0.1102

0.0E35

0.0162

O.(ml

0.0036

0.4s72

004s2

0.0121

0.0265

O.lKI1

0.1244

QLQ9za

u.uob3

0.0034

0.4460

00466

0.0126

0.-

0.1571

0.2036

Qo3zl

0.W043

0.0034

0.4224

0.0462

0.0123

o.02m

0.1647

0.2133

9J.QU

O.ouu

0.WS2

Oiw

Omm

0.0132

0.0224

0.1723

0.2232

QJ m9

0

O

0

O

0

O

0

0

Q

old 1lwoo 1.Lkxxr

1.Oow 1JJow

Md Wel@d

Gr’2vty,AH

243.0 201.0 221.0

392

37.3

W4

le40

45.0

TUlrp2mllwe,F

Pre6um,W

m4

234 f14

3334 2512

mm

2m

4923

T@bla 3

RESERVOIR FUJID FROM ‘6’ FIELD

Preswm @2

J -

J&–

J@d

A1.– &-

%

cat

c.

O.olw

0.0046

0.92543

O.ow

o.oo3a

0.0040

O.wm

0.0006

0.713

0.076

0.07s

0.117

0.016

0.0122

0.0Q46

0.227s

0.028s

0.W36

0.0037

0.0049

0.0C415

-

0.0140

oao45

0.2222

0.0347

0.0037

O.WM

0.2040

0.0004

0.0176

0.0346

0.2W4

0.0371

0.0U32

O.mw

0.UM3

osroo2

A

0.0146

0.W4

0.4319

o.m44

0 M44

0.0023

o.oCe2

O.WQ1

-

0.739

0.077

0.075

O.om

0.010

=

0.761

O.on

0.071

0.023

O.om

=

0.7s2

O.om

0.067

0.070

0.004

=

0.816

o.on

0.060

0.046

MN

=

1.000

ad

1.mxlo 1.lm

loom

1.mo 10JOO

1.000 t.Oooo 1.WI l,om

T2t424

R~Wn;:EID

~

O.lwz

0.0013

0.0010

%, 0.0200

0.0166

0.0173

c, 030541 0.2616

0.2325

C.@, 0.2171

0.2073 0.2015

c,

0.0407

0.0430 0.0444

c,.c.

0.06s4

O.(WS O.wss

C,-c,, 0.1s73

0.1s66 0.1063

C,,J2=

0.1629

0.17$0

O.lw

%

RJ&tR

Q.QzQz QQz65

Total

I.omo

1.0000

1mm

R2s2RwlRFL4AD’Fm.n

two

~~

.usd_

xi

.IaL

xii+.

J--

00047

0.0046

aoo44

0.0322

0.0314

0.0322

O.sml o.@xYl

0.W26

Pr4B41m


7/10


8/10

FIGURE 3

SIMULATED LABORATORY SLIMTUBE EXPERIMENT

6

c

z“

o

m

g

$

1.0 z

TEMPERATURE:164*F

&

g

PRESSURE:2500 PSIO

~

PURE CARBON DIOXIDE

0.1

I

I

1

I

I I

I I

I

I I

1

I I 1

I I

I

o

0.2

0.4

0.6

0.8

1.0

FRACTIONAL OISTANCE

FIGURE 5


“FmFIELD RESERVOIR FLUID

Lo

115000

OJ

1

1

, ,

4

0

0.2

0.4

0.6

0.8

Lo

L2°

FLIHO INJECTED,PORE VOLUMES

FIGURE 4


“B’FIELD RESERVOIR FLUID

1.0)

115000

0.8

A

In

TEMPERATURE: 164°F

Ill PRESSUR&2500 @Cl

>

PURE CARBONDIOXIDE

m

=

- 10000~

d

> 0.6

in

u

o“

Ix

Er i=

o

<

n

a

.

g 0.4

w

-

5000 s

a

t

a

u

0

w

a 0.2

0

0

0.2

0.4

0.6

0.8

Lo

L2°

FLUID INJECTED,PORE VOLUMES

FIGURE 6


COMPOSITION OF GAS AND LIQUID PHASES

o.OOO,o~o

.

.

.

FRACTIONAL OISTANCE


9/10

FIGURE 7

SIMULATED LABORATORY SLIMTU8E EXPERIMENT

“WFIELO RESERVOIR FLUIO

1.0

0.8

8000

VI

TEMPERATURES164*F

PRESSURE:2500 Psla

m

%

\

n

IL.

A

0

0

> 0.6

6000 ?

Er

~

WI

Z*

K

o

c

a.

~“ 0.4

4000 g

w

-

2

G

u

v

a

0.2

00

0.2

0.4

0.6

0.8

Lo

FLUID INJECTED.pORE VOLUMES

FIGURE 9

SIMULATEO LABORATORY SLIMTUBE EXPERIMENT

COMPOSITION OF GAS ANO LIOUIO PHASES

1.0

0.0001

ii

11

iJ

1

,

t

o

0.2

0.4

0.6

0.8

Lo

FRACTIONAL DISTANCE

FIGURE 8

SIMULATEO LABORATORY SLIMTUBE EXPERIMENT

INTERFACIAL TENSION

‘oo”o~

oooo,~

0

0.2

0.4

0.6

0.8

TEMPERATURE 164°F

PREsSURG2500 psla

ETHANE PLUS SOLVENT

FRACTIONAL OISTANCE

FIGURE 10


‘F-FIELD RESERVOIR FLUIO

1.0

- 10000

0.8

8000

TEMPERATUR& 234°F

PREssuRE:i750 psla

m

0.6 -

Er

P

0.4 -

+

0.2 -

0

0

0.2

0.4

0.6

0.8

FLUID INJECTED,PORE VOLUMES


10/10

1-

Z

Wms’otlvu lIOPWJ

1-

S3NIl10A 3tJOd”AWA033U

a

JJllf

1

1111111 1

1

111111i 1 1

Iulll I

1

L

~pE 20190

ul&VSOU~P’NofSN31 1V13VAM31NI

A Study of the Mechanisms of Carbon Dioxide Flooding and Applications to More Efficient EOR Projects

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Transcript of A Study of the Mechanisms of Carbon Dioxide Flooding and Applications to More Efficient EOR Projects