l1-phase behavior fundamentals

Termodinamica de Hydrocarburos

(Phase Behavior of Hydrocarbon Fluids)

Fall, 2006

Phase Behavior Fundamentals and Review of Thermodynamics

BucaramangaDiciembre, 18-22, 2006Instructor: Dr. Maria A. Barrufet

Welcome DiscussionClass starts at 8:00 A.MClass ends 5:00 p.m+ ?Lunch from 12:00 to 12:30?Coffee/tea breaks in the morning and in the afternoon10 Minute breaks every 50 minutes of classA mix of lectures, discussions, and exercises morning and afternoon

Welcome DiscussionInformal class - ask questions at any timeAutobiographical sketchObjectives of CourseRulesDisable all cell phonesBe in class ON TIMEAvoid talking to neighbors (public discussions only)

Maria A. BarrufetEducation University National of Salta (Argentina) B.S. Chemical EngineeringUniversity National of Sur (Argentina) M.S. Chemical Engineering Texas A&M University Ph.D. Chemical EngineeringProfessor in the Petroleum and Chemical Engineering Departments of Texas A&M University

Teaching Experience Numerical Physics Of Reservoir Simulation Enhanced Oil Recovery ProcessesThermalChemicalMisciblePVT/Phase BehaviorEngineering Near Critical Reservoirs (compositional reservoir simulation)Reservoir EngineeringThermal Recovery Processes (detailed)Applied Reservoir SimulationWaterflood Management

Class MaterialsPower Point PresentationsSelected SPE papers and bibliography in day-by-day folderExcel files and useful software DigitizerSteam Properties Fluid Property CalculatorExcel ExercisesTernary diagramHomework practicesEtc.

Schedule Day 1Course Introduction: Thermodynamic Concepts and Definitions. Mathematics and Programming Tools Basic Phase Behavior. Single Component Systems.Two-Component Systems.Three-Component Systems.Multi-Component Systems

Schedule Day 1 (more)Phase Diagrams: Volumetric and phase behavior of pure substances, binary and multicomponent systems. Phase diagrams (P-V, P-T, P-x, y-x).Hydrocarbon Phase Behavior. Classification of Reservoir Fluids Based Upon Phase Diagrams, Fluid Compositions, and Production DataTernary Diagrams. Phase Equilibria Representation

Schedule Day 1.Examples & Homework.

ReferencesLecture Notes from Maria Barrufet (MAB)The Properties of Petroleum Fluids William McCain Jr. Pennwell (1990) (WM)Properties of Oils and Natural Gases Pedersen et al. (PFT)Phase Behavior SPE Monograph 20 Curtis Whitson and Michael Brule (CW)Hydrocarbon Phase Behavior Tarek Ahmed Gulf Publishing Co. (1989). (TA)Selected Papers from the SPE and other Journals.Selected Internet sites to be announced. (I)

Additional References

Power point presentations Other library papers (AIChe, Journal of Fluid Phase Equilibria, Journal of Petroleum Engineering Science and Technology)

Grading Police

30% HW & Discussions35% Exam 1 in class35% Exam 2 take home

Graphical, Analytical, Math Skills Required

Understand 3-D plots and 2-D projections (slices)Derivatives (analytical, numerical & graphical)Partial Derivatives (numerical & analytical)Integration (analytical and numerical)Solution of non linear equationsRoot finding routines

Graphical, Analytical, Math Skills Required

Units and conversions (dimensional analysis)Numerical analysisDependent and independent variablesSolution of simultaneous equations

Learning ObjectivesAfter completing this section you will be able to:Understand pure component phase behavior as a function of pressure, temperature, and molecular size.Understand the behavior of binary and multicomponent mixtures.

Learning ObjectivesAfter completing this section you will be able to:Construct single (pure) component phase diagrams (PT), (PV)Construct temperature composition diagrams for a fixed pressure or pressure composition diagrams for a fixed temperature.Construct ternary phase diagrams (fixed P & T)

The Need to Understand Phase Behavior

As oil and gas are produced from the reservoir, they are subjected to a series of pressure, temperature, and compositional changes. Such changes affect the volumetric and transport behavior of these reservoir fluids and, consequently, the produced oil and gas volumes.

The Need to Understand Phase BehaviorType of reservoir fluid determines depletion and production strategies and the design of surface facilitiesExcept polymer flooding, all of EOR methods rely on the phase behavior of reservoir fluids and fluids injected into the reservoir. This behavior is used to classify the recovery method (i.e., thermal, miscible, chemical, etc.), and to design the recovery process.

Major DefinitionsSystem: A body of matter with finite boundaries (physical or virtual) Closed System: Does not exchange matter with surroundings but may exchange energy (heat).Open System: Does exchange matter and energy with surroundings.

Major DefinitionsHomogeneous System: Intensive properties change continuously and uniformly (smoothly)

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

Major DefinitionsPhase: A portion of the system which has homogeneous intensive properties and it is bounded by a physical surface. Interface: Separates two or more phases. These phases are solid, liquid(s), and gas.

Major DefinitionsIntensive Properties: Independent of system mass (i.e density)Extensive Properties: Dependent of system mass (i.e volume)

Major DefinitionsProperties: Characteristics of a system (phase) that may be evaluated quantitatively, i.e.Phase density (liquid, gas, solid)Phase compositionsIsothermal compressibilitySurface tensionViscosity Heat capacityThermal conductivity

Major DefinitionsComponent: A molecular species, defined or hypothetical.

Defined: Cl, C2, H2O, etc.

Hypothetical: lumped defined (i.e. C2-C6), or undefined C7+ , C20+

Major DefinitionsState: Condition of a system at a particular time determined when all intensive properties are fixed

Phase DiagramsThe most common types of phase diagrams are

Single: (PT), (PV), (TV)Binary: (PT)zi, (PV)zi, (P,x,y)T, (T,x,y)P

Single Component Phase Diagram (PT)

Vapor Pressure Curve

Pressure vs Specific Volume Pure Component

Pure Component PropertiesTabulated critical properties (notes)

Hydrocarbon Families Physical Properties

Heat Effects Accompanying Phase Changes of Pure Substances

Clapeyron & Clausius Clapeyron Equations

Heat Effects from Phase Changes of Pure Substances

Heat Effects from Phase Changes of Pure Substances

Approximate relation (Clausius - Clapeyron Equation)

COX - Vapor Pressure Charts(normal paraffins) PressureTemperature heavier Non-linear scaleLog scale

Two Component SystemsPhase Diagrams

Pressure Composition Diagrams - Binary Systems

Hydrocarbon CompositionThe hydrocarbon composition may be expressed on a weight basis or on a molar basis.

Hydrocarbon CompositionBy convention liquid compositions (mole fractions) are indicated with an x and gas compositions with a y.

Mathematical Relationships

with

In general

Temperature vs. Composition Diagrams Binary Systems TemperaturePressureBubble CurveDew Curve2-phasesx1, y1PaPaCP1CP2T1sT2sT2sT1s01

3-D PhaseDiagram(P,x)T(T,x)P

Quantitative Phase Equilibrium Exercise

Typical Black-Oil System

Supercritical Conditions Binary Mixture

Depletion PathIsothermal Reservoir Depletion Process for a Reservoir Oil with 2 ComponentsTemperaturePressurePDPBT = TaTaCPMz1 = fixedz1y1x110ABCz1=overall mole fraction of [1],y1=vapor mole fraction of [1],x1=liquid mole fraction of [1]

Pressure-Temperature Diagram for Multicomponent Systems

Quantitative Phase Equilibrium Exercise

Changes During Production and Injection

Ternary Diagrams: Review

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Ternary Diagrams: ReviewPressure EffectC3C3

Ternary Diagrams: ReviewDilution Lines

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Ternary Diagrams: ReviewQuantitative Representation of Phase Equilibria - Tie (or equilibrium) lines

Tie lines join equilibrium conditions of the gas and liquid at a given pressure and temperature.Dew point curve gives the gas composition.Bubble point curve gives the liquid composition.

Ternary Diagrams: ReviewQuantitative Representation of Phase Equilibria - Tie (or equilibrium) lines

All mixtures whose overall composition (zi) is along a tie line have the SAME equilibrium gas (yi) and liquid composition (xi), but the relative amounts on a molar basis of gas and liquid (fv and fl) change linearly (0 vapor at B.P., 1 liquid at B.P.).

Illustration of Phase Envelope and Tie Lines


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Uses of Ternary DiagramsRepresentation of Multi-Component Phase Behavior with a Pseudoternary DiagramTernary diagrams may approximate phase behavior of multi-component mixtures by grouping them into 3 pseudocomponents

heavy (C7+)intermediate (C2-C6)light (C1, CO2 , N2- C1, CO2-C2, ...)

Compositional Distribution ofReservoir Fluids

Uses of Ternary Diagrams

Phase behavior of solvent/reservoir fluid mixtures Pre-design of miscible processes

Uses of Ternary DiagramsFirst Contact Miscible Recovery Processes (FCM)solvent mixes completely with the reservoir oil in all proportions, such


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ExerciseFind overall composition of mixture made with 300 moles oil "O" + 50 moles of mixture "A".__________________________________________________________________________________________________________________________________


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Practice Ternary DiagramsPressure Effect

Practice Ternary DiagramsTemperature Effect

l1-phase behavior fundamentals

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