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Measurement of Phase behaviour.pdf
- 1. 1 Initials Schlumberger Private Schlumberger Private Measurements of Phase Behavior (Routine PVT Testing)
- 2. 2 Initials Schlumberger Private Schlumberger Private Objectives Understand • Definition of PVT properties • Procedures of lab measurements • Calculation or data processing • Trend of properties
- 3. 3 Initials Schlumberger Private Schlumberger Private Contents • Equipment – PVT system • Recombination of surface samples • Constant composition expansion • Differential liberation • Separator test • Constant volume depletion
- 4. 4 Initials Schlumberger Private Schlumberger Private DBR Phase Behavior Equipment PVT System • Pressure: displacement pump • Volume: cathetometer • Temperature: oven
- 6. 6 Initials Schlumberger Private Schlumberger Private PVT Cell and Volume Determination
- 7. 7 Initials Schlumberger Private Schlumberger Private PVT Samples • Bottom hole sample – Preferred • Well head sample – Not recommended unless single phase at wellhead • Surface sample – Recombination
- 8. 8 Initials Schlumberger Private Schlumberger Private PVT Testing Sequence Sample Restoration Composition CCE DL Separator Test Viscosity Gas Condensate or Volatile Oil Black Oil CVD Separator Test Viscosity
- 9. 9 Initials Schlumberger Private Schlumberger Private Recombination of Separator Samples ƒ For saturated reservoir: saturation pressure is the reservoir pressure and that is the parameter we target for recombination. ƒ For under saturated reservoir: GOR is the target for recombination. 9 Production data required for recombination: GOR
- 10. 10 Initials Schlumberger Private Schlumberger Private Recombination Setup Temperature Controlled Oven Boundary DBR JEFRI Recombination Cell Pressure Gauge Sep. Oil DBR JEFRI Sample Cylinders Sep. Gas DBR JEFRI Injection Pump
- 11. 11 Initials Schlumberger Private Schlumberger Private Recombination of Separator Samples (Continued) • Once the separator liquid/gas have been proportioned together, the mixture is pressurized to a pressure higher than the estimated (or known) saturation pressure and agitated, all at the reservoir temperature. Light oil takes as little as few hours to equilibrate and heavy oil takes several weeks to equilibrate. • Once the recombined sample is homogeneous, its composition is analyzed by single stage flash. Then compare with the calculated composition from the separator sample compositions.
- 12. 12 Initials Schlumberger Private Schlumberger Private Composition of Recombined Sample
- 13. 13 Initials Schlumberger Private Schlumberger Private Constant Composition Expansion ( CCE) CME, P-V Relation „ Saturation pressure „ Phase volumes „ Bulk density (2-phase) Masstotal/ Vtotal „ Single phase compressibility „ Relative volume Vtotal/Vsaturation
- 14. 14 Initials Schlumberger Private Schlumberger Private CCE for a Black Oil – An Isothermal Process Liq Oil Liq Liq Gas Oil Liq Oil Liq P1 P2 < P1 P3 < P2 P4 < P3 P5 < P4
- 15. 15 Initials Schlumberger Private Schlumberger Private Phase Diagram (PT) Medium Oil Ps 90 80 70 60 50 Ps 2φ VL Pressure Temperature 1φ L
- 16. 16 Initials Schlumberger Private Schlumberger Private Graphical Estimation of Black Oil Bubble Point Pressure Psat = 2280.5 psig Vsat = 65.83 cm3 Single Phase Two Phase 63 64 65 66 67 68 69 4500 4000 3500 3000 2500 2000 1500 Total Volume (cm3) Pressure (psig)
- 17. 17 Initials Schlumberger Private Schlumberger Private Response of Bubble Point on SDS
- 18. 18 Initials Schlumberger Private Schlumberger Private Black Oil CCE Data Table Pressure Liquid Relative Liquid Compressibility Y- (psia) Volume % Volume Density Co Function (%) Vr=Vtot/Vsat (g/cm 3 ) (10 -6 psi -1 ) Value 8000 100.00 0.955 0.729 6.8 7400 100.00 0.959 0.726 7.4 6800 100.00 0.964 0.723 8.1 6200 100.00 0.969 0.719 8.8 5600 100.00 0.974 0.715 9.7 5000 100.00 0.980 0.711 10.5 4400 100.00 0.986 0.706 11.5 3700 100.00 0.995 0.700 12.7 Psat 3300 100.00 1.000 0.697 13.4 3100 96.40 1.020 3.317 2500 84.72 1.105 3.054 1900 70.74 1.264 2.790 1300 53.11 1.610 2.524 700 30.66 2.653 2.248 Psat - P P(V/Vsat - 1) a= 0.91101367 b= 0.14561416 c= 6693.0791 - d(lnVr) Y-Function is only valid for Pressures < Psat dP Equations for the Relative Volume and Fluid Compressibility are only valid for Pressures > Psat Constant Composition Expansion @ Tres Black Oil PVT Study Vr = a+ b exp(-P/c) Co = Y = P - psia
- 19. 19 Initials Schlumberger Private Schlumberger Private CCE for Gas Condensate Oil Gas Oil P1 P2 < P1 P3 < P2 P4 < P3 P5 < P4
- 20. 20 Initials Schlumberger Private Schlumberger Private Phase Diagram (PT) Gas Condensate Ps 90 80 70 60 50 40 30 20 10 Ps C Ps 2φ VL Pressure Temperature 1φ G 1φ L
- 22. 22 Initials Schlumberger Private Schlumberger Private Liquid Dropout from a CCE (Gas Condensate) Cloud seen at ~ 5000 psia Pressure (psia) % Liquid 20 18 16 14 12 10 8 6 4 2 0 500 1500 2500 3500 4500 5500 6500 ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ ƒ • • • • •
- 23. 23 Initials Schlumberger Private Schlumberger Private Differential Liberation (DL) Designed to simulate a pressure depletion process „ All gas generated below the bubble point is assumed to be produced Measured Data „ Gas oil ratio (GOR) / Liberated Gas „ Formation volume factor, Bo „ Gas properties: MW, density, Z, Bg „ Liquid properties: density, viscosity
- 24. 24 Initials Schlumberger Private Schlumberger Private Schematic Representation of a Differential Liberation Experiment V 1 = V sat V 2 < V sat V 3 = V 2 < V sat V 4 = V 3 = V 2 < V sat V 5 < V 4 < V sat P1 = Psat P2 < Psat P2 < Psat P2 < Psat P3 < P2 < Psat Gas Off
- 25. 25 Initials Schlumberger Private Schlumberger Private DL Oil Property Table Calculated Oil Oil Oil Density FVF 2 Viscosity (g/cm 3 ) (bbl/STB) (mPa-s) 3300 0.697 1.456 0.38 2500 0.721 1.363 0.46 22.6 1700 0.745 1.282 0.57 33.2 1000 0.766 1.218 0.73 47.9 500 0.782 1.173 0.93 65.6 15 0.815 1.036 1.87 171.6 Dead Oil Density at STD Conditions (60°F & 15.0 psia) 0.844 g/cm 3 ; 36.1 °API 1 Gas Volume @ STD / Residual Oil @ STD 2 BO, Reservoir Oil Volume @ P,T per Unit Volume of Residual Oil @ STD 3 Gas Viscosity Calculated from Lee et al. correlation (psia) Oil/Gas 3 Cumulative Produced Solution Gas GOR GOR 1 (scf/STB) DIFFERENTIAL LIBERATION TEST - LIQUID PHASE PROPERTIES Liquid Data GOR Data Pressure RS 1 (scf/STB) Viscosity Ratio 824 0 0 211 824 613 431 536 393 288 191 633
- 26. 26 Initials Schlumberger Private Schlumberger Private DL Gas Property Table Vapor Vapor Vapor Z Gas Total Two Phase Calculated Density MW Gravity 1 Factor 2 FVF 3 FVF 4 Co Gas Viscosity 6 (g/cm 3 ) (g/gmol) (air=1) (ft 3 /scf) (bbl/STB) (10 -6 psi -1 ) (mPa-s) - - - - - 1.5 - - 20.390 20.4 0.707 0.875 0.0066 1.6 853 0.0203 20.050 20.1 0.695 0.884 0.0097 1.8 1222 0.0172 20.420 20.4 0.708 0.910 0.0171 2.5 2248 0.0153 22.010 22.0 0.763 0.939 0.0352 4.2 5447 0.0142 49.220 49.2 1.707 0.989 1.2580 136.0 847205 0.0109 1 Vapor Phase MW/MWAir 2 Z=PV/nRT 3 BG, Reservoir Gas Volume @ P,T / Gas Volume @ STD 4 BT, Oil FVF + [(Total liberated gas)* Gas FVF] 5 Co=-1/Bo[(dBo/dP)-BG(dRs/dP)] 6 Lee et al. Correlation (Lee A., Gonzales M.H., Eakin B.E., JPT, 997-1000, Aug., 1966) (psia) Pressure Vapor Data Total DIFFERENTIAL LIBERATION TEST - VAPOR PHASE PROPERTIES 3300 15.0 500 1000 1700 2500
- 27. 27 Initials Schlumberger Private Schlumberger Private GOR Plot 0 100 200 300 400 500 600 700 800 900 0 1000 2000 3000 4000 5000 6000 7000 Pressure (psia) Gas Oil Ratio (scf/STB) Solution GOR (Rs) as a Function of Pressure
- 28. 28 Initials Schlumberger Private Schlumberger Private Liquid Viscosity Plot 0 0.5 1 1.5 2 0 1000 2000 3000 4000 5000 6000 7000 Pressure (psia) Oil Viscosity (cP) Oil Viscosity as a Function of Pressure
- 29. 29 Initials Schlumberger Private Schlumberger Private Liquid Density Plot 0.6 0.7 0.8 0.9 0 1000 2000 3000 4000 5000 6000 7000 Pressure (psia) Oil Density (g/ml) Oil Density as a Function of Pressure
- 30. 30 Initials Schlumberger Private Schlumberger Private Formation Volume Factor Plot 1 1.1 1.2 1.3 1.4 1.5 0 1000 2000 3000 4000 5000 6000 7000 Pressure (psia) Bo (cf/scf) Bo as a Functions of Pressure
- 31. 31 Initials Schlumberger Private Schlumberger Private Constant Volume Depletion (CVD) Designed to simulate a pressure depletion process – Volatile oil and gas condensate „ Only gas is produced below the saturation pressure Measured Data „ Produced gas volumes „ Liquid volume fraction „ Gas properties: MW, density, Z, Bg „ Liquid properties: density, viscosity
- 32. 32 Initials Schlumberger Private Schlumberger Private Constant Volume Depletion for a Gas Condensate P1 = Psat Gas P2 Gas Oil P3 < P2 < Psat Gas Oil V 1 = V sat V 2 > V sat V 3 = V sat V 4 > V sat P2 Gas Oil P2 < Psat Gas Oil Gas off
- 33. 33 Initials Schlumberger Private Schlumberger Private CVD Data Tables for a Gas Condensate
- 34. 34 Initials Schlumberger Private Schlumberger Private Multi-Stage Separator Test Simulates the Surface Separation Process „ In the past several were run to optimize separation conditions (liquid yield) Measured Data „ GOR – total and separator „ Gas properties, MW, density, Z factor, heating value, plant liquids, etc. „ Liquid formation volume factor „ Liquid properties, density, etc.
- 35. 35 Initials Schlumberger Private Schlumberger Private SCHEMATIC OF A TWO STAGE SEPARATOR GOR SCF/Sep BBL @T°, P° Feed Well Head Gas GOR SCF/Sep BBL @ Tr , Pr Oil Oil (STO) Gas G L G L 1st Stage Separator Conditions 2nd Stage Ambient Conditions T1 , P1 T2 , P2 Standards are: T° = 15°C P° = 1 atm
- 36. 36 Initials Schlumberger Private Schlumberger Private Volumetric and Density Data for a Separator Test
- 37. 37 Initials Schlumberger Private Schlumberger Private Quality Assurance Overall mass balance Overall mole balance Individual component molar balance Equilibrium
- 38. 38 Initials Schlumberger Private Schlumberger Private CONSISTENCY CHECK OF COMPOSITIONAL DATA (Equilibrium) K - value (yi/xi) Molecular Weight (g/mol)
- 39. 39 Initials Schlumberger Private Schlumberger Private Fluid Viscosity Resistance to fluid flow Newtonian fluid: viscosity invariant with flow rate Measurement: – Control flow rate, measure force: capillary viscometer – Control force, measure flow rate: rolling ball, electromagnetic viscometer, etc. dy dv A F µ =
- 40. 40 Initials Schlumberger Private Schlumberger Private Electromagnetic Viscometer Piston p1 V V V Coils T = constant
- 41. 41 Initials Schlumberger Private Schlumberger Private Summary Constant composition expansion Differential liberation Constant volume depletion Multi-stage separation test Viscosity