B Rock Phys 1
rock physics
rock physics
Kartei Details
| Karten | 31 |
|---|---|
| Sprache | English |
| Kategorie | Naturkunde |
| Stufe | Universität |
| Erstellt / Aktualisiert | 11.04.2013 / 04.08.2017 |
| Weblink |
https://card2brain.ch/box/b_rock_phys_1
|
| Einbinden |
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AVO stands for and is
Amplitude Vs Offest
analyses the effect of incidence angle on the seismic amplitude.
What do Gassman's equations do?
They relate a materials resistance to compression (bulk modulus) to its compositional makeup .
What do Gassmann's equations take into account?
the properties of the rocks matrix, pore space and pore fluids
In order to allow the estimation of changes in seismic velocity that result from changes in pore fluid you neewd to.
Calculate the bulk modulus of a saturated rock.
Bulk Modulus
K
resistance to compression
Poisson’s Ratio
Vp/Vs or σ
Measure of incompressibility
How can we limit the possible values of rock properties resulting from the strucutre of the pore space
Use theory to estimate upper and lower bounds of the elastic moduli
In order to simulate elastic media need to know
• Volume fractions of constituents • Elastic moduli of various constituents • Geometric details of relationships between constituents, how rock stuck together – rock frame
Voight-Reuss bounds do not take into account...
pore space structure
Voigt average is
stiffest rock possible
(rock cannot be stiffer than the average of the components)
Reuss average is
softest rock possible
what does the location of a rock between bounds depend on
the geometry of the pores
(for Voigt-Reuss)
What does the Voigt-Reuss-Hill average give
an estimate of the modulus rather than a range
(halfway between the Voigt and Reuss averages)
Hashin-Shtrikman bounds difference with Voigt-Reuss
Hashin-Shtrikman bounds-isotropic
Voigt-Reuss-anisotropic
(the narrowest range of elastic moduli bounds without specifying anything about the rock frame geometry for H-S)
compaction effect on P-Velocity
(also Voigt Reuss lines on P-Velocity graph)
.
effect of clay content on Vp
.
Sorting trend on Vp-Velocity graph
.
Basic Assumptions of Gassmann's (5)
HOuses IN FRance are CLean CHateaus
The rock is macroscopically homogeneous
All pores are interconnected
Pores filled with frictionless fluid
Rock-fluid system closed
Pore fluid does not interact with the solid to soften or harden the frame
Variables assumed in fluid substitution
inital fluid properties
final fluid properties
matrix properties
Compaction trends for sands versus clays
.
What does the Marion model do
predicts velocity-porosity of sand-shale mixes.
Marion Model porosity Vp relationship
.
OOIP
STOOIP
OOIP=hydrocarbon volume underground
STOOIP=hydrocarbon volume above ground
isotropic
anisotropic
Isotropic – assume rock properties same in all directions Anisotropic – rock properties change with direction
locations of the different classes on an AVO plot
clockwise from bottom right, 1, 2 ,3
~bbl in 1m3
6.3
~m2 in an acre
4047
AVO crossplot diagram
.
The constant value that converts acre-feet to stock tank barrels
7758
tuning
A phenomenon of constructive or destructive interference of waves from closely spaced events or reflections
AVO crossplot gives information on
fluid fill and litholgy
