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PETE 310

PETE 310. Lecture # 5 Phase Behavior – Pure Substances. Learning Objectives. After completing this chapter you will be able to: Understand pure component phase behavior as a function of pressure, temperature, and molecular size.

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PETE 310

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  1. PETE 310 Lecture # 5 Phase Behavior – Pure Substances

  2. Learning Objectives After completing this chapter 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 (lectures 6 & 7)

  3. 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.

  4. The Need to Understand Phase Behavior • Except 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.

  5. Major Definitions • System: 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.

  6. Major Definitions • Phase: 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.

  7. Major Definitions • Intensive Properties: Independent of system mass (i.e density) • Extensive Properties: Dependent of system mass (i.e volume)

  8. Major Definitions • Homogeneous 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

  9. Major Definitions • Properties: Characteristics of a system (phase) that may be evaluated quantitatively. These are, • Phase density (liquid, gas, solid) • Compressibility • Surface tension • Viscosity • Heat capacity • Thermal conductivity

  10. Phase Diagrams • Types of phase diagrams for a single component (pure substance) • (PT) • (PV) or (Pr) • (TV) or (Tr)

  11. Fusion Curve Critical 2 phases Point P c Solid Liquid (1 phase) (1 phase) Pressure Vapor Pressure Curve (2 phases) Vapor (1 phase) Triple Point (3 phases) Sublimation Curve (2 phases) T Temperature c Phase Diagrams Single Component Phase Diagram

  12. Critical Point r P l c Pressure Liquid r v Vapor T c Temperature Phase Diagrams Vapor Pressure Curve

  13. Hydrocarbon Families Physical Properties One point in the Vapor Pressure Curve

  14. T ) psia CP Tc Pressure ( 2-phase V V L v Specific Volume (ft3 / lbm) Pressure vs Specific Volume Pure Substance

  15. Pure Component Properties • Tabulated critical properties (McCain)

  16. d P v Lv = T D V dT Heat Effects Accompanying Phase Changes of Pure Substances Clapeyron equation Btu/lb-mol With DV = VMg-VMl

  17. d P v Lv V dT Lv d P v P v dT 2 R T Heat Effects Accompanying Phase Changes of Pure Substances = T D Approximate relation (Clausius - Clapeyron Equation) =

  18. Example of Heat Effects Accompanying Phase Changes • Steam flooding Problem: Calculate how many BTU/day (just from the latent heat of steam) are provided to a reservoir by injecting 6000 bbl/day of steam at 80% quality and at a T=462 oF

  19. COX - Vapor Pressure Charts(normal paraffins) Log scale heavier Pressure Temperature Non-linear scale

  20. 1 2 3 4 5 gas gas b V V V = V t1 t2 V t3 t4 t5 V liquid liquid liquid liquid liquid Hg Hg Hg Hg Hg >> P P > P P = P P = P P =P P 1 s 2 s 3 s 4 s 5 s Determination of Fluid Properties Ps =saturation pressure Temperature of Test Constant

  21. Vapor Pressure Determination T2 Pressure P S T1 V L Volume

  22. Homework • See Syllabus for HW Problems due

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