Competing Effect of Pore Fluid and Texture -- Case Study

Transcription

1 Competing Effect of Pore Fluid and Texture -- Case Study Depth (m) Sw Sxo. m Poisson's Ratio.. GOC P-Impedance OWC 15 GR.. RHOB.5 1 Saturation Vs (km/s).. Poisson's Ratio 5 7 P-Impedance Negative velocity contrast at gas-oil contact 1

2 Elastic Moduli and Crossplot Elastic Moduli vs. Depth Cross-Plot Cross-Plot by Zones and Common Fluid Substitution Depth (m) 5 5 Depth > OWC GOC < Depth < OWC Depth < GOC m M (GPa) M (GPa) GOC OWC WATER SUBSTITUTION 15 GR.. M-Modulus (GPa) G-Modulus (GPa)

3 Rock Texture Diagnostic by Effective-Medium Models 8 5 Constant Contact Cement Contact Cement M (GPa) G (GPa) 15 GOC Uncemented (Friable) WATER SUBSTITUTION OWC GR

4 GRANULAR ROCK EFFECTIVE-MEDIUM MODELS 5 Velocity- Dry Sandstones - MPa Oseberg Diversity in Sandstones P-Wave Velocity (km/s).1 Troll Ottawa+ Clay Well.. Log. Vs (km/s) 1 QUARTZ Consolidated Suspension Reuss Bound Critical Concept 8 SANDSTONES 5 SANDSTONES M-Modulus (GPa) Shear Modulus (GPa) Diagenesis Quartz Sandstone Sand Suspension Frame-Supported Fluid-Supported φ c POROSITY %

5 Critical -- Two Extreme Examples Solid Fractured Structure Bulk Modulus (GPa) 5 SOLID GLASS Frame-Supported Foam Disintegrated Foam Honeycomb Structure Calcite CHALKS POROUS GRAINS CRACKED IGNEOUS ROCKS Compressional Modulus (GPa) 8 Cracked Igneous Rocks with Percolating Cracks Pumice with Honeycomb Structure Various Materials Material Critical Sandstones % Limestones % Dolomites % Pumice 8% Chalks 5% Rock Salt % Cracked Igneous Rocks 5% Oceanic Basalts % Sintered Glass Beads % Glass Foam 9% 5

6 Critical Models and Diagenesis OSEBERG M-Modulus (GPa) Depth m TROLL Marl GR 5 1 Vs (km/s)..5 RHOB.1. Velocity 5 P-Impedance Contact Cement Equation Unconsolidated Shale Equation.1

7 Contact Cement and Diagenesis Well 1 Back-scatter Well 1 Cathodoluminescent Quartz Cement Contact Cement.1 mm P-WAVAE VELOCITY (km/s) Clay Cement CORE DATA SATURATED Non-Contact Cement.. POROSITY 7

8 Contact Cement Theory Uncemented Grains Cemented Grains CONTACT STRESS NO GRAINS: GLASS : EPOXY Contact Stress X.5.1 x/r EXPERIMENT THEORY Normal Stress SOFT MEDIUM STIFF Soft Cement.1. x/r.1. x/r.1. x/r Stiff Cement 8

9 Importance of Contact Cement Cemented GLASS BEADS ED GLASS BEADS 8 Uncemented (Percent) 8 Confining Pressure (MPa) LOOSE GLASS BEADS AFTER Why Cement Preserved Grains Normal Stress No Coordinate along Cement Layer 9

10 ARTIFICIAL MATERIALS 5 Upper HS GLASS-EPOXY Contact Cement Examples JC Self-Consistent Compressional Modulus (GPa) 5 Lower DEM Lower HS Contact Cement Model.1 (Void Concentration) Upper HS QUARTZ-ICE QUARTZ CLAY RESERVOIR-RELATED Dry-Rock Vp at MPa (km/s) CONTACT FRIABLE Sleipner Well 1 Log Oseberg Compressional Modulus (GPa) Self-Consistent JC Lower DEM Lower HS Troll Contact Cement Model.1 (Void Concentration)

11 Grains without Cement -- Hertz-Mindlin Contact Theory dt df F a F df dt Hertz-Mindlin Contact Solution Contact Stiffness a R = (1 ν) π G C(1 φ) P S n S τ = ag 1 ν = 8aG ν MODIFIED LOWER HASHIN-SHTRIKMAN WITH HERTZ-MINDLIN M-Modulus (GPa) 8 SOLID Increasing Pressure HERTZ- MINDLIN.1 Dry Rock MPa Differential Pressure Dry Rock MPa Differential Pressure Troll Ottawa+Clay Ottawa Near-Wellbore Damage?.5 Vs (km/s)

12 Modified Lower Hashin-Shtrikman -- Applications Wilmington Field -- Oil Behind Casing.1 Density- (Open Hole) Dipole Sonic (Cased)..5 Depth (ft) 5 Dipole Density 7 Shallow Sea- Bottom Sediment Depth (mbsf) 8 1 Data This Model Suspension a Neutron b P-Wave Velocity (km/s) 1

13 Appendix -- Elastic Bounds Voigt and Reuss Composite Voigt Reuss M V = f i M i M R = ( N i=1 N i =1 f i M i 1 ) 1 Hashin-Shtrikman 5 5 Hashin-Shtrikman Bounds: Realization Effective Bulk Modulus (GPa) Voigt Reuss 5 Hashin-Shtrikman Effective Shear Modulus (GPa) 5 Voigt 5 Reuss 15 Hashin-Shtrikman Clay Content Clay Content 5 Voigt Reuss Hashin-Shtrikman Clay Content N f i [ K i + G ] 1 i =1 min G K min eff [ [ [ N i =1 N i=1 G i + G min G i + G max f i 9K min + 8G min K min + G min f i G eff 9K max + 8G max K max + G max ] 1 N i =1 G min ] 1 G max f i K i + G max ] 1 G max 9K min + 8G min K min + G min 9K max + 8G max K max + G max 1

14 GP17/1 # Cementation in Well Log Data WELL LOG DATA WELL LOG DATA WELL LOG DATA COMPRESSSIONAL MODULUS (GPa) COMPRESSSIONAL MODULUS (GPa) COMPRESSSIONAL MODULUS (GPa) LOUISIANA.1 POROSITY NORTH SEA.1 POROSITY NORTH SEA (Heimdal) LOUISIANA.1 POROSITY 1