PETE 310 Lecture # 5 Phase Behavior – Pure Substances.

PETE 310PETE 310

Lecture # 5Lecture # 5

Phase Behavior – Pure Phase Behavior – Pure SubstancesSubstances

Learning ObjectivesLearning Objectives

After completing this chapter After completing this chapter you will be able to:you will be able to:

Understand pure component Understand pure component phase behavior as a function of phase behavior as a function of pressure, temperature, and pressure, temperature, and molecular size.molecular size.

Understand the behavior of Understand the behavior of binary and multicomponent binary and multicomponent mixtures mixtures (lectures 6 & 7)(lectures 6 & 7)

The Need to Understand The Need to Understand Phase BehaviorPhase Behavior

As oil and gas are produced from the As oil and gas are produced from the reservoir, they are subjected to a reservoir, they are subjected to a series of pressure, temperature, and series of pressure, temperature, and compositional changes. compositional changes.

Such changes affect the volumetric Such changes affect the volumetric and transport behavior of these and transport behavior of these reservoir fluids and, consequently, reservoir fluids and, consequently, the produced oil and gas volumes.the produced oil and gas volumes.

The Need to Understand The Need to Understand Phase BehaviorPhase Behavior

Except polymer flooding, all of EOR Except polymer flooding, all of EOR methods rely on the phase methods rely on the phase behavior of reservoir fluids and behavior of reservoir fluids and fluids injected into the reservoir. fluids injected into the reservoir.

This behavior is used to classify This behavior is used to classify the recovery method (i.e., thermal, the recovery method (i.e., thermal, miscible, chemical, etc.), and to miscible, chemical, etc.), and to design the recovery process. design the recovery process.

Major DefinitionsMajor Definitions

System:System: A body of matter with A body of matter with finite boundaries (physical or finite boundaries (physical or virtual) virtual)

Closed System:Closed System: Does not exchange Does not exchange matter with surroundings but may matter with surroundings but may exchange energy (heat).exchange energy (heat).

Open System:Open System: Does exchange Does exchange matter and energy with matter and energy with surroundings.surroundings.

Major DefinitionsMajor Definitions

Phase:Phase: A portion of the A portion of the system which has system which has homogeneous intensive homogeneous intensive properties and it is bounded properties and it is bounded by a physical surface. by a physical surface.

Interface:Interface: Separates two or Separates two or more phases. These phases more phases. These phases are solid, liquid(s), and gas. are solid, liquid(s), and gas.

Major DefinitionsMajor Definitions

Intensive Properties:Intensive Properties: Independent of system Independent of system mass (i.e density)mass (i.e density)

Extensive Properties:Extensive Properties: Dependent of system mass Dependent of system mass (i.e volume)(i.e volume)

Major DefinitionsMajor Definitions

Homogeneous System:Homogeneous System: Intensive Intensive properties change continuously and properties change continuously and uniformly (smoothly)uniformly (smoothly)

Heterogeneous System:Heterogeneous System: System made up System made up of two or more phases in which the of two or more phases in which the intensive properties change abruptly at intensive properties change abruptly at phase-contact surfacesphase-contact surfaces

Major DefinitionsMajor Definitions

Properties:Properties: Characteristics of a Characteristics of a system (phase) that may be system (phase) that may be evaluated quantitatively. These are,evaluated quantitatively. These are, Phase density (liquid, gas, solid)Phase density (liquid, gas, solid) CompressibilityCompressibility Surface tensionSurface tension Viscosity Viscosity Heat capacityHeat capacity Thermal conductivity Thermal conductivity

Phase DiagramsPhase Diagrams

Types of phase diagrams for a Types of phase diagrams for a single component (pure single component (pure substance)substance)

(PT)(PT) (PV) or (P(PV) or (P)) (TV) or (T(TV) or (T

Phase DiagramsPhase Diagrams

Single Component Phase DiagramSingle Component Phase DiagramP

ress

ure

P c

TemperatureT c

Liquid (1 phase)

Vapor (1 phase)

Solid

(1 phase)

Sublimation Curve (2 phases)

Triple Point

(3 phases)

Vapor Pressure

Curve (2 phases)

Critical

Point

Fusion Curve2 phases

Phase DiagramsPhase DiagramsVapor Pressure CurveVapor Pressure Curve

Pre

ssu

re

Temperature

Vapor

Liquid

Critical Point

l

v

Pc

T c

Hydrocarbon Families Hydrocarbon Families Physical Properties Physical Properties

One point in theOne point in theVapor Pressure CurveVapor Pressure Curve

Pressure vs Specific Pressure vs Specific Volume Pure SubstanceVolume Pure Substance

Tc

2-phase

T

Specific Volume (ft3 / lbm)

Pre

ssu

re (

psi

a)

Vv

VL

CP

Tabulated critical properties Tabulated critical properties (McCain)(McCain)

Pure Component Pure Component PropertiesProperties

Heat Effects Accompanying Heat Effects Accompanying Phase Changes of Pure Phase Changes of Pure

SubstancesSubstances  

Lv = TV dPv

dTWith

V = VMg-VMl

Btu/lb-mol

Clapeyron equation

Heat Effects Heat Effects Accompanying Phase Accompanying Phase

Changes of Pure Changes of Pure SubstancesSubstances

  Lv = TV dPv

dT

=

Approximate relation (Clausius - Clapeyron Equation)

dPv

dT

RT2 Pv

Lv

Example of Heat Effects Example of Heat Effects Accompanying Phase Accompanying Phase

Changes Changes Steam flooding Problem:Steam flooding Problem:

Calculate how many BTU/day Calculate how many BTU/day (just from the latent heat of (just from the latent heat of steam) are provided to a steam) are provided to a reservoir by injecting 6000 reservoir by injecting 6000 bbl/day of steam at 80% quality bbl/day of steam at 80% quality and at a T=462 and at a T=462 ooF F

COX - Vapor Pressure COX - Vapor Pressure ChartsCharts

(normal paraffins)(normal paraffins)

Pre

ssu

reP

ress

ure

Temperature Temperature

heavier heavier

Non-linear scaleNon-linear scale

Log scaleLog scale

Determination of Fluid Determination of Fluid PropertiesProperties

Temperature of Test Constant

Vt1

Vt2

Vt3

=V

b

Vt5

Vt4

liquid liquid liquidliquid

liquid

gas gas

Hg Hg HgHg

Hg

P1 >> P

sP

2 > P

sP

3 = P

sP

4 = P

sP

5 =P

s

1 2 3 4 5Ps =saturation pressurePs =saturation pressure

Vapor Pressure Vapor Pressure DeterminationDetermination

Pre

ssur

e

PS

Volume

VL

TT22

TT11

HomeworkHomework

See Syllabus for HW Problems See Syllabus for HW Problems due due