3_PP-412 Digrama de Fases - Monofasico - Multifasico.pdf

GAS NATURAL YGAS NATURAL YGAS NATURAL YGAS NATURAL YCONDENSADOS ICONDENSADOS ICONDENSADOS ICONDENSADOS I

PPPPPPPP----412412412412

Ing. William Navarro

A PARTIR DE:

DIAGRAMA DE FASES-PRUEBAS PVT

CARACTERIZACIN DE YACIMIENTOS EN BASE A LA MEZCLA DE HIDROCARBUROS QUE CONTIENEN

DIAGRAMA DE FASES-PRUEBAS PVT

INFORMACIN DE PRUEBAS DE PRODUCCIN

IntroduccinIntroduccinIntroduccinIntroduccin

Gas y petrleo son mezclas de fluidos que estn sujetos a diferentes ambientes de P & T

Estas medios se denominan Phases. Phase es una porcin homognea de un sistema

heterogneo Es homogneo en su composicin Es homogneo en su composicin Posee superficies limites Son separables fsicamente

Entender el comportamiento de phase permite determinar el comportamiento de los fluidos en el reservorio y en el sistema de produccin-transporte.

DefinicionesDefinicionesDefinicionesDefiniciones

Sistema

Amount of substance within given boundaries under specific conditions composed of a number of components.

If anything moves across the boundary system will have changed.have changed.

Componentes

Sustancias puras que producen el sistema a lascondiciones de P y T.

Ejem. C1, C2, CO2, agua


Phase

Porcin fsica distinta de materia, que tiene propiedades fsicas y qumicas uniformes.

Ejem. Agua liquida-Hielo.

Equilibrio Equilibrio

Un sistema esta en equilibrio cuando no ocurren cambios en el tiempo de sus propiedades fsicas


Propiedades intensivas

Independientes de la cantidad de materia. Ejem. Densidad, volumen especifico, factor de

compresibilidad

Propiedades extensivas Propiedades extensivas

Dependen de la cantidad de materia presente. Ejem. Volumen

PRESIN TEMPERATURA ATRACCIN MOLECULAR REPULSIN MOLECULAR

FACTORES FSICOS QUE CONTROLAN EL FACTORES FSICOS QUE CONTROLAN EL FACTORES FSICOS QUE CONTROLAN EL FACTORES FSICOS QUE CONTROLAN EL COMPORTAMIENTO DE FASESCOMPORTAMIENTO DE FASESCOMPORTAMIENTO DE FASESCOMPORTAMIENTO DE FASES

PRESIN Y Confinan las MolculasATRACCIN MOLECULAR

TEMPERATURA Y Dispersan las MolculasREPULSIN MOLECULAR

TemperaturaTemperaturaTemperaturaTemperatura ---- PresinPresinPresinPresin

PresinPresinPresinPresin Refleja la frecuencia de colisin de las moleculas en las

paredes del contenedor. Ms moleculas incrementa presin.

Fuerzas de atraccinFuerzas de atraccinFuerzas de atraccinFuerzas de atraccin----repulsin entre repulsin entre repulsin entre repulsin entre Fuerzas de atraccinFuerzas de atraccinFuerzas de atraccinFuerzas de atraccin----repulsin entre repulsin entre repulsin entre repulsin entre moleculas.moleculas.moleculas.moleculas.

Fuerzas de atraccin aumentan a medida que la distancia entre las moleculas disminuye hasta que las cargas se superponen.

Al disminuir ms la distancia se incrementa las fuerzas de repulsin

TemperaturaTemperaturaTemperaturaTemperatura ---- PresinPresinPresinPresin

Temperatura

Indicativo de la energa Cinetica de las moleculas. Si se adiciona calor se incrementa energa Kinetica Las moleculas se mueven ms separados.

Gases & LiquidosGases & LiquidosGases & LiquidosGases & Liquidos

Gases

Molecules are widely spaced. Attractive forces exist between the molecules.

Liquidos

Molecules are closer together. Molecules are closer together. Repelling force which causes liquid to resist

further compression.

SistemaSistemaSistemaSistema PuroPuroPuroPuro

Useful to examine pure systems to gain insight into more complex hydrocarbon systems.

Phase diagrams Plots of pressure versus temperature or pressure

versus volumeShow the phases that exist under varying conditions. Show the phases that exist under varying conditions.

DiagramaDiagramaDiagramaDiagrama PPPP----TTTT


Vapour pressure line

Divides the regions where the

substance is a liquid from regions

where it is a gas

Conditions on the line indicate where

both liquid and gas coexist.


Critical PointThe limit of the vapour

pressure line

Defines the:

Critical temperature, TCritical temperature, Tc

Critical pressure, Pc

of the pure substance

For pure component, the

limiting state for liquid and

gas to coexist.General definition:

The point at which all intensive properties of the

gas and liquid are equal


Triple Point

Represents the pressure and

temperature at which solid, liquid

and vapour

co-exist under equilibrium

conditions.conditions.

Not common for Petroleum

engineers to deal with solid state.

More recently an issue in the

context of wax, ashphaltenes and

hydrates.


Sublimation -Pressure

Line


temperature at which solid exists

from the area where vapour from the area where vapour

exists.


Melting Point Line


temperature at which solid exists

from the area where liquid exists.

Of relevance to wax and hydrates

DiagramaDiagramaDiagramaDiagrama PPPP----TTTTConsider behaviour of a PVT (pressure, volume, temperature ) cell

charged with a pure substance and the volume varied by frictionless

piston.

P1 Single phase liquid at P1


Single phase liquid at P1

P1 P2

Significant pressure reduction

Small liquid volume change

Bubble point

pressure

P2P2

Small gas bubble in

equilibrium with

liquid


P1


P2

Bubble point

pressure P2

P3

Further volume

expansion

More gas phase.

Liquid volume decreases

Pressure remains

constantconstant


P1


P2

Bubble point

pressure P2

P3

Further volume

expansion

P4

Dew point

pressure P4

Small liquid drop in

equilibrium with gasequilibrium with gas

Pressure remains

constant


P1


P2

Bubble point

pressure P2

P3

Further volume

expansion

P4

Dew point

pressure P4

P5Further gas

expansion

Pressure reducesPressure reduces

Diagrama P-T

P1

P2

P3P4

P5

BehaviourBehaviourBehaviourBehaviour across the across the across the across the vapourvapourvapourvapour pressure linepressure linepressure linepressure line

From A to B via VP line

At A liquid phase

P1

Between A&B on VP

line gas & liquid phases

P3

line gas & liquid phases

At B gas phase

P5

BehaviourBehaviourBehaviourBehaviour around the critical pointaround the critical pointaround the critical pointaround the critical point

At A liquid phase

At E compressed liquid

phase

From E to F from liquid

At G gas phase

At B gas phase

From E to F from liquid

to gas with no phase

boundary

Beyond critical pointBeyond critical pointBeyond critical pointBeyond critical point

At 3 liquid phase ?

Dense phase fluid

From 3 to 4 a change from

liquid properties to gas

At 4 gas phase

liquid properties to gas

properties with no distinct

phase change

DiagramaDiagramaDiagramaDiagrama PPPP----T T T T EtanoEtanoEtanoEtano

DiagramaDiagramaDiagramaDiagrama PresinPresinPresinPresin----VolumenVolumenVolumenVolumen

1. Single phase liquid

Bubble point

first gas bubble

Dew point

P1

P2

P4

T = Tc critical temperature

Single phase region

Dew point

Last drop of liquid

All gas

P5 TTc Smooth change from liquid to gas. No

definite phase distinction.Reflects compressibilty of

liquid

DiagramaDiagramaDiagramaDiagrama PresinPresinPresinPresin----VolumenVolumenVolumenVolumen

A series of expansions

at various constant

temperatures yield

pressure volume

diagram.

Gives the focus of the

bubble point and dew

Single phase

bubble point and dew

point values.

Liquid

GasTwo distinct phases

DiagramaDiagramaDiagramaDiagrama PresinPresinPresinPresin----VolumenVolumenVolumenVolumen EtanoEtanoEtanoEtano

Three Dimensional Phase Diagram for a Three Dimensional Phase Diagram for a Three Dimensional Phase Diagram for a Three Dimensional Phase Diagram for a Pure ComponentPure ComponentPure ComponentPure Component

SistemaSistemaSistemaSistema dos dos dos dos ComponentesComponentesComponentesComponentes

Such a system is called a binary One component more volatile than the other. Components are miscible

SistemaSistemaSistemaSistema dos dos dos dos ComponentesComponentesComponentesComponentesDiagramaDiagramaDiagramaDiagrama PresinPresinPresinPresin----VolumenVolumenVolumenVolumen

Isotherm similar to pure

component

Pressure decreases as system

goes from bubble point to dew

point

Composition of liquid and vapour

phases change from bubble point

to dew point

Physical properties function

of composition

e.g.density

SistemaSistemaSistemaSistema dos dos dos dos ComponentesComponentesComponentesComponentesDiagramaDiagramaDiagramaDiagrama PresinPresinPresinPresin----VolumenVolumenVolumenVolumen

Compositions

Component light

Component heavy

Liquid mixture

At bubble point

Liquid Gas

At dew point

Liquid Gas

Gas mixture

SistemaSistemaSistemaSistema dos dos dos dos ComponentesComponentesComponentesComponentes

The diagram is for

a 52.4 mole%

mixture of

N-heptane and

N-pentaneN-pentane

A finger print of

the mixture

SistemaSistemaSistemaSistema dos dos dos dos ComponentesComponentesComponentesComponentesDiagramaDiagramaDiagramaDiagrama PresinPresinPresinPresin----TemperaturaTemperaturaTemperaturaTemperatura

Compared to a single line

representing two phase

behaviour for pure

substances,

a broad region in which

two phases co-exist

characterises 2

component systems


Bubble point line and dew

point line meet at critical point.

A mixture has a critical

temperature and pressure.

These values are NOT the

compositional averages of the

critical values of the pure

components.


Bubble Point

Within 2 phase region

proportions of liquid and gas.

These are termed quality lines

Dew point

By carrying out a series of

constant temperature expansion

phase envelope is defined


A specific mixture will give a

specific phase envelope.

Increase the proportion of A

and the envelope will change

shape and move to the left.

Increase the proportion of B

and the envelope will change

shape and move to the right.

PCAB much greater than PCA and PCB

DiagramaDiagramaDiagramaDiagrama PPPP----T T T T emperatureemperatureemperatureemperatureEtanoEtanoEtanoEtano ----HeptanoHeptanoHeptanoHeptano

Critical points for various

mixtures

Pure component critical values

Locus of the mixture critical

points

Diagrama de Fases de una mezcla de gasDiagrama de Fases de una mezcla de gasDiagrama de Fases de una mezcla de gasDiagrama de Fases de una mezcla de gasnatural natural natural natural ---- gasolina naturalgasolina naturalgasolina naturalgasolina natural

27002600

100%90%80%70%60%

50%

25002400230022002100

GAS0%

LQUIDOA % LQUID

O

L

p

c

a

LQUIDO + VAPOR (GAS)

60

50%

40%

30%

20%10%

210020001900180017001600150014001300

80 100 120 140 160TEMPERATURA, F

P

R

E

S

I

N

,

L

180 200 220 240 260

LQUIDO + VAPOR (GAS)

PuntoPuntoPuntoPunto CriticoCriticoCriticoCriticoMezclaMezclaMezclaMezcla de HCsde HCsde HCsde HCs

Mixture of methane and

n-octane has a critical point much

greater than pure component values

Pure component critical values

Two phases exist within this

boundary

Methane is a significant component

of reservoir fluids

CondensacinCondensacinCondensacinCondensacin RetrogradaRetrogradaRetrogradaRetrograda

Within the two phase region of our two component system there can be temperatures higher than the critical temperature and pressures higher than the critical pressure.

The cricondentherm.

Is the maximum temperature at which two phases Is the maximum temperature at which two phases can exist in equilibrium.

The cricondenbar.

Is the maximum pressure at which two phases can exist in equilibrium.


Cricondenbar

Examine behaviour at

constant temperature

between critical temperature

and cricondentherm of

pressure decrease

1

2

At 1 single phase fluid

At 2 dew point

Cricondentherm

At 2 dew point

3

At 3 maximum

liquid4

At 4 dew point5

At 5 single gas phase

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3_PP-412 Digrama de Fases - Monofasico - Multifasico.pdf