2.
A sandstone has a porosity of 10% which is filled with water. The
velocity of the P wave in the matrix of the sand grain is 4 km/sec.
The average P wave velocity in the rock is
1.
3.22 km/sec
2.
3.42 km/sec
3.
3.62 km/sec
4.
3.82 km/sec
Solution:
Sandstone
porosity Ø = 10% = 0.1
Matrix
velocity of the P wave = 4 km/sec
Fluid
velocity (Vf)= 1.5km/sec
From
Wyllie law:
$\frac{1}{V_r}
= \frac{\phi}{V_f}+\frac{1-\phi}{V_m}$
Vr
- is the velocity of the rock
Vf
- is the velocity of the fluid (1.5 km/s)
Vm
- is the velocity of the matrix
Ø
- porosity
$\frac{1}{V_r}
= \frac{0.1}{1.5}+\frac{1-0.1}{4}$
= 0.066 + 0.3225
$
\frac{1}{V_r} = 0.2917$
$V_r
= 3.42 km/s$
Please solve this
ReplyDeleteThe combined elevation correction In gravity units for a station. At height of 10 meters above datum plane. For a surface density Of 2000 kg/ m³ Is
How you can assume fluid velocity...???
ReplyDeleteSorry , That is P-wave velocity in the water or liquid or fluid is 1500 m/s and we know that S-wave velocity in the water is zero.
ReplyDeleteI'm not assuming ,its a standard value.
ReplyDeletehttps://pangea.stanford.edu/courses/gp262/Notes/8.SeismicVelocity.pdf
ReplyDeleteAbove problem they clearly mention that pores are filled with water(P wave velocity is 1500m/s). if it's filled with oil instead of water (P- wave velocity is 1250 m/s).
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