FLUID PROPERTIES

FLUID PROPERTIES

1. PHASE

   • any homogenous (all liquid, solid or gas) part of system separated from other parts by definite boundary surface
   • eg: ice water: 2 phase (l+g)
   • PHASE BEHAVIOR
     • P-T diagram
       • describe phase behavior (equilibria) betw. phases as changes P,V,T of system
       • single component
         • SUBLIMATION curve (s-g), VAPOR PRESS curve (l-g)
         • CRITICAL POINT
           • critical temp
             • at higher temp than critical temp, incr. press will not liquefy gas
           • critical press
             • at higher press than criticalpress, incr. temp can't coexist gas & liquid
         • TRIPLE POINT
           • temp, press which liquid, solid, gas coexist under equilibrium condition
       • two-component
         • BUBBLE POINT curve: down first bubble gas formed
         • DEW POINT curve: up first liquid drop form
         • CRITICAL POINT: bubble point & dew point curves meet, all properties of liquid & gas are identical
         • CRICONDENBAR: max. press on curves, above always liquid
         • CRICONDENTHERM: max.temp on curves, always gas
         • QUALITY line: temp & press for equal V of liquids, show ratio liquid:gas
     • conditions of temp & Press for which different phase exist
     • Subcooled/compressed liquid: liquid phase that has pressure higher than vapour pressure (above vapour press curve)
     • Superheated Vapor: gas phase that has higher temp than vapor temp (below vapor press curve)

2. PURE SUBSTANCES

   • uniform&invariable in chemical composition
   • can exist in >1 phase but each phase must have same chemical composition
   • eg: ice water is a pure substance with 2 phases

3. SYSTEM: what we want to study

   • CLOSED SYSTEM
     • no mass loss from system
   • ISOLATED SYSTEM
     • no energy lose from system
   • system condition described by its properties
     • eg: condtion STATE described by p,V, T

4. SURROUNDINGS: everything external to system

5. BOUNDARY: separate system from surroundings

6. PHYSICAL PROPERTIES

   • INTENSIVE
     • independent of quantity of material presented (p,Temp,press)
   • EXTENSIVE
     • dependent of quantity of material presented (V, mass)

7. COMPOSITION

   • C-4:$$$, C-7: cheap

8. RESERVOIR FLUID TYPES

   • decide factors: sampling, prediction, calculation, recovery method, type/size equipment, depletion plan
   • confirmed by: lab observations, production info
   • determined by fluid properties: initial production GOR, gravity & colour of stock-tank fluid
   • Oil reservoir
     • reservoir temp < critical temp
     • UNDERSATURATED: can dissolve more gas, > bubble-point press
     • SATURATED: can't dissolve more gas, =bubble point press
     • GAS-CAP/2-PHASE: <bubble point press
     • HEAVY oil (BLACK)
       • equally spaced quality line, brown/dark green
     • Light oil ( VOLATILE)
       • closer-wider down quality line, green/orange
   • Gas reservoir
     • reservoir temp > critical temp
     • RETROGRADE CONDENSATE gas
       • closer-wider right quality line, >gas as press decr, white/colour liquid in stock-tank
     • WET gas
       • white liquid in stock-tank
     • DRY gas
       • only gas in tank/ water

9. decr. temp& press - decr. VISCOSITIES fluid

10. COMPRESSIBILITY

    • decr. press - compress effect gas cap, compaction drive