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Seismic velocities. Can be written as function of physical quantities that describe stress/strain relationsDepend on medium propertiesMeasurements of velocitiesDefinitions of velocities (interval, rms, average etc.)Dix formula: relation between rms and interval velocitiesAnisotropy. Physical quantities to describe stress-strain properties of isotropic medium.
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1. Seismic Velocities
2. Seismic velocities Can be written as function of physical quantities that describe stress/strain relations
Depend on medium properties
Measurements of velocities
Definitions of velocities (interval, rms, average etc.)
Dix formula: relation between rms and interval velocities
Anisotropy
3. Physical quantities to describe stress-strain properties of isotropic medium Bulk modulus k volume stress/strain
Shear modulus ? shear stress/strain
Poissons ratio ? transverse/longitudinal strain
Youngs modulus E longitudinal stress/strain
4. Bulk modulus
5. Shear modulus Where tau is the shear stressWhere tau is the shear stress
6. Poissons ratio
7. Youngs modulus
8. Seismic Velocities in a homogeneous medium
10. Seismic velocity Depend on
Matrix and structure of the stone
Lithology
Porosity
Porefilling interstitial fluid
Temperature
Degree of compaction
11. Seismic Velocity depending on rock properties Ss= sand,sandstone LS= limestone, DO=DolomiteSs= sand,sandstone LS= limestone, DO=Dolomite
13. Measurements of velocities Laboratory measurements using probes
Borehole measurements
Refraction seismics
Analysis of reflection hyperbolas
Vertical seismic profiling
16. Different people have investigated the velocity of P-waves for various lithologies 1-7. They all found different values
Range of values and the overlap!Different people have investigated the velocity of P-waves for various lithologies 1-7. They all found different values
Range of values and the overlap!
18. Velocities
19. Several horizontal layers
20. Dix Formula
21. Anisotropy