The mapping of three phase volumetric behavior of pseudo-binary

Fluid Phase Equilibria, 39 (1988) 3255332 Elsevier Science Publishers B.V., Amsterdam

325 -Printed

in The Netherlands

YHE MAPPINGOF TBREE PHASE VDLUMETKICBEHAVLOROF PSEUDO-BINARY SYSTEMS Short

ON PRESSURE-COMPOSITION

DIAGRAMS

Commmication

Nick Pollack, Department

Robert

Enick

of Chemical

6 Petroleum

Engineering

1249 Benedum Ball University

of

Pittsburgh,

Pittsburgh

PA, USA

15261

(412)624-9649 (Received

May 7,

1987;

accepted

in final

form November

II, 1987)

ABSTKACT Pollack, N. and Enick, R., 1988. The mapping of three phase volumetric behavior of pseudo-binary systems on pressure-composition diagrams. Fluid Phase Equilibria, 39:325-332. A method behavior

of

illustrated one

has

for

bounded

regions.

been

developed

pseudo-binary the

two types

by three

A diagram

CO2-Maljamar

of

two-phase of a three

separator

for

the

systems

crude

on

multiple

regions phase

oil

mapping P-x

phase

and one

region,

system

of

three

diagrams.

phase

regions

usually

bounded

by only

based

also

is

encountered, two two-phase

on experimental

at 304K, is

volumetric

The technique

data

for

the

behavior

of

presented.

INTKOllUCTION There

have

been many investigations

pseudo-binary

systems

dioxide/crude

oil

results

these

of

systems

behavior

(P-x)

at

These

categories

as illustrated

the two diagrams 1.

multiple

phase

regions,

037%3812/88/$03.50

tertiary

Figures

these

near

can

be

1 and 2.

such

recovery.

presented

Many of

phase

mixtures,

oil

typically

regions

volumetric

liquid

and pressures

phase in

the

and

the

carbon

Phase behavior

in

systems

classified

as

the

form

exhibit

critical into

The distinguishing

point

of

multiple of

the

two distinct features

of

are;

The multiple phase

are

to

diagrams. (I)

temperatures

solvent,

into

solvent

pertaining

studies

pressure-composition phase

containing

LL-V,

region

shown in

Figure

L1-L2 and L2-V. (2)

0 1988 Elsevier Science Publishers B.V.

1 is

bounded

by three

two-

326

.8

.7

Figure

.9 B MOLE FRACTION SOLVENT

A

1. Three-Phase Data for

2.

Region Bounded by Three Two-Phase Regions,

a Multicomponent

The three

phase

an upper

two phase shown.

region

lines

of constant

The

phase

the

inspection. volumetric

It data

of high the

of

Pseudo-binary

illustrated region

in Figure

(L2 -V)

conditions.

(Ll-V)

It

since is

region

of

the three

this

to

demonstrate

behavior

in

is

the

three

not

phase

bounded by

region

has “gone

phase

region

presented

region

are

a method of of

liquid-

(Ll-L2).(l)

Ll or L2 are often

the boundaries paper

2 is

that

bounded by a lower

and a liquid-liquid volume percent

Isothermal

System

for

typically

mapping

a P-x diagram

for

the any

system.

proposed

evaluating

series

only

The purpose

pseudo-binary

since

at these

vapor

regions,

volumetric

region

liquid-vapor

critical”

Although

1.0

+ D

&

three

narrow pressure

mapping

technique

consistency will

predicted pressure phase

of

also

offer

will

experimental

experiments. of

range at elevated

these

of

a

phase

a preliminary

by an equation

region

provide

useful behavior

method of

state

against

These experiments types

pressures.

of

tool

systems

Constructing

for

data

comparing those

quickly

by

visual

the

phase

generated

by a

must be done carefully oten

exist

over

a map of this

a very region

327 2000

7.9

7.8

1120

Ll L2 g

ii 1090 i? B iz

1060

7.3

7.2

1030

.80(E)

.70

.90(F)

MOLE FRACTION

Figure

2. Three-Phase

Gl

C&

Region Bounded by Two Two-Phase Regions,

Separator

Crude

Experimental

Oil

Data,

System,

304

K,

Open

Broken Curves and Solid

C02/Maljamar

Points

Refer

Curves Correspond

to to X

L2 and % L1, Respectively.

is

very

sensitive

results,

therefore,

Note single

that

are

since

pressure,

a Px diagram. temperature

the

to

likely

the

this

accuracy

An apparent

and pressure

the

pressure

to be difficult

three

multiple

of

phase

vs.

equipment.

The

to reproduce.

behavior

phase volumetric

density

measuring

of

binary

behavior

systems cannot

phase volume diagram

must be employed in these

occurs

at

be described

at the three

a on

phase

(3)

cases.

NAPPINGMKTHOD The procedure is

similar

to

determination different relative

of

overall phase

experimental

used to define

that

used

relative

in

volumetric

two

phase

phase

volumes

CO2 compositions volume-pressure

data or equation

behavior

regions.

as a function

throughout relationships

of state

in the three This

predictions.

of

the

three

can

be

phase region

method

requires

pressure

at

the

several

phase

region.

The

obtained

either

from

The

horizontal

series

illustrate

the

cell

conducting

while

A through and

volumetric

pressure

region

at

three

to

phase

phase

as

where

in

the

the

L1 phase.

the

phase

of

the

the

a

fraction

of

Ll and L2 phases

in

procedure

is

fractions

in a two-phase

identical

and pressures are

The lower to

ox L2.

upper

boundary

between

and Y in

at

the

behavior that region, Figure

of

three

for

with

amounts 3C -

the of

traces

of

Figure

Y and

p 1-5

p 26-30

appear

exist

within

but may also 3A,

3G -

is

amount of Ll in Figure

usually

in

X in

are

close

3G - p 26-30

on the to is

the

phase

liquid region,

corresponds

1 and the entire of

the

upper

At points

of

the

3A -

p 2-4).

are

present

V

L2 and V Similarly

along

with

1 the V phase dominates 3D -

At this

p 22-24). point

this

single

curves

of

point.

volume Note

two

phase

(The amount of

Ll in

lOO%, but

may be leas.

the

At

the lower

The phase

region.

close

volume

the overall

to 0% Ll.

two phase

usually

liquid

diagrams

(Figure

at

saturation

This

phases.

intersect-

would occur the

the sum

of

amounts

critical.

0% V,

since

The portion

Figure

for

phases;

to

three

both

(Figure

Ll,

three

1 and 2. of

three

Ll and V phases

as

have been drawn for

fraction

1 corresponds

the Ll and L2 phases

Z can

defined

the

Ll phase

2, the L2 and V phases

shown in

In

minute

Ox L2, and the upper boundary,

points

volume

0% V.

At point

p19).

the

corresponding

only

the

such

in an isochore

V and W in Figure

to

respectively,

a phase,

construction

region

points

overall

Figures

two of the

phase

between

overall

Isochores

the

the each

of

two of

of

in of

and

thereby

isochore.

W and X in Figure

small

is

toe

these

pressure

of

only

a specified

an

2 corresponds

equilibrium

2 in Figure

boundary,

the

Figure

(Figures

presence

of

boundary

1 and 2,

W, only

the L2 phase in

in

form

values

the

regions

in

from

resulting

unity.

rmtst be performed

points

Figures

exist

point

point

of

used

end of

different

as

phase

MPa, the

volumes

1 the

apparent

behavior

where the points

at which to

boundary

The upper

boundary

phases

joined

the procedure

that

region,

three

phase

for

phase

the

phase

joined,

phase

muLtiple

to

phase

however,

third

amst equal

the

compositions exist

the

fractions

example,

relative

to

must be determined

of

is

fraction

then

by lines

would be observed

P15 (7.5

several

volume

are

a visual

multiple

the

correspond

phase

region

Isochores

for

which

specific

the

3G

“G” in Figures For

that

It

in

indicated

beginning

1.

through

observed

respectively.

83%) to

record

3A

“A” through

volumes

Figure

describe

only

pressure

phase

volume

of

be

experiments

lines 3G,

Figures

would

MPa, the

B in

to

need

points

three

volume

phase

(6.9

line

of

The

composition

Pll

order

one

function

a

composition.

occurs

in

region,

that

the phase

CO2 composition along

in

compression

3A through

from

region) that

three

behavior

3B represents

an overall

illustrations

illustrated

The vertical

Figures

increases

phase

phase

1 and 2.

shown in Figure

the

cells

the isothermal

G in Figure

2 correspond

cells

of

Similarly,

to OX, but may be more.)

the

329

7

Figure

3.

Refer

The

Illustrations

to Overall

multiple

constructed Figure

4

is

an

crude

isothermal

identical

oil

at

oven.

with

was accelerated

calibrated

by with

the

the volume of

diagram

used

in

was mixed with pressure,

of

positive

by rocking

was then put

measuring

P-x

the

cell

in an upright

height the cell.

of

the

1 and 2

shown

previous

Figure study

amounts

position,

shown in

position

and the with

phase Maljamar within

by injecting

Equilibration

a horizontal

interfaces

of

contained

was achieved pump.

2 was

multiple

windowed cell

in

in

used in this

various

mixture

displacement the

Letters

in Figures

The apparatus

that

304K in a high

a high pressure

The cell

the

Compression

mixture

determined

of

dioxide

Phase Behavior,

Indicated

data. to

Carbon

mercury

minutes.

region

experimental

experiments.(3s4) separator

of Multiple

Compositions

phase

using

a

a

phase

of

the

for

ten

volumes

cathetometer

330

Dh

CARBON TANK

NIT&N TANK

MERCURY PUMP

TRANSDUCER

P %!F

DRAIN

Figure

Note during

that

the

the

course

measurements achieved

of

the

introduce

the

experiments Viatram Their

respective

oil

which

region,

Pollack

Apparatus

four

into

and CO2 charged

pump, calibrated

were were

requires into

both

used

to

the

the cell

using

7 to

21 MPa.

.Ol

cm3, oil

a 35 MPa Heise

injected

accurate

was

published

was then

gauge

times

accurate This

cell.

in

to

obtain

four

very

from

The minimum volume of

Furthermore,

accuracies

ranging

pressures

the cell.

transmitter

was reproduced

and Enick,c5)

the amount of CO2 initially at

was 3 cm3.

pressure

of

displacement

oil

Experimental

phase

study,

amounts

data

positive

three

this

by calculating

compressibility pressure

narrow of

4.

A high used

during

to the

and a 70 MPa

pressure

readings.

.1 and .25 percent.

BBSULTS The three compressions

at

phase overall

region

for

this

system

CO2 concentrations

is of

shown in Figure .70,

.80,

.85,

2. .90,

Isothermal .95 and .99

331 were

performed

volumetric extrapolated

approximately

to

define

smooth and continuous

sufficient,

indication

region

(just

phase region

of

presented

different

and

of

the three

in

order

of

obtain

enough

Y and 2 were

The data produced

phase region. This provides

a necessary,

the volumetric

smooth and continuous

to

Pofnts

L2 isochores.

isochores.

the accuracy

as the

of

this

Yu, and Lien.(6)

those

MPa increments

Ll

but not

data in the multiple

nature

of

lsochores

in a two-

would).

The boundaries Orr,

.02

the

from the boundaries

relatively

phase

at

data

by

phase region

Although Orr,

at higher

three

et

our

al.,

results

the

were investigated are,

shapes

of

in

general,

the

three

previously consistent

phase

by with

region

are

CO2 concentrations.

CONCLUSIONS A method for on

P-x

phase

diagrams regions

another

has

for

This

mapping technique

each

phase

present

of

boundaries

of this

this

The technique that

the

at

phase

developed.

Two general

An example of

separator

provides

of

crude

Pseudo-binary

categories

this oil

phase

within

the

region

have

of

systems

these

two-phase

three-

regions

mapping technique

and

has been

system at 304K.

a means of determining

any point

multiple

behavior

one bounded by three

two.

the C02/Maljamar

descriptions

in

been

multiple

have been described,

one bounded by only

presented

of

describing

three

the relative

phase

been

limited

region. to

amount Previous

defining

the

region. also

isochores

provides for

each

a measure of of

the

the accuracy

equilibrium

phases

of experimental should

data

be smooth and

continuous.

NRFERBNCES

Stalkup, Orr,

F.,

Miscible

Displacement,

F.M. and Jensen, C.M., Diagrams for C02/Crude-Oil

SPE, New York (1983),

“Interpretation of Systems,” SPEJ, Oct.

Enick, R., Holder, G. and Morsi, B., Carbon Dioxide/Tridecane System,” 224, 1985.

pp.

6-23.

Pressure-Composition 1984, pp. 485-497.

Phase

“Critical and Three Phase Behavior of the Fluid Phase Equilibria, Vol. 2.2, pp. 209-

Description of Multiple Enick, R., Holder, G. and Mangone, D., “A Generalized Phase Behavior in Isothermal, Isobaric Systems,” Proceedings of the Fourth International Conference on Fluid Properties and Phase Equilibria for Chemical Process Design, Fluid Phase Equilibria Elsevler, 1986.

332 PO1lack, N-R., Enick, R.M., Morsi, B.I. and Mangone, D.J., "The Effect of an Aqueous Phase on the COz/Tetradecaneand C02/MaljamarCrude Oil Systems: Experimentaland Modeling Results," paper SPE 15400 presented at the 61st Annual Technical Conference and Exhibition of the Society of Petroleum Engineers, New Orleans, LA, Oct. 5-8, 1986 (in press, WE Reservoir Engineering). Orr, P.M., Yu, A.D. and Lien, C.L., "Phase Behavior of CO2 and Crude Oil in Low TemperatureReservoirs,"SPEJ, Aug. 1981, pp. 480-492.