Page 243 - Well Logging and Formation Evaluation
P. 243
Solutions to Exercises 233
0.5
0.4
0.3
PORn 0.2
0.1
0
4000 4200 4400 4600 4800 5000 5200 5400
Vp (m/s)
These show considerable scatter, and I do not believe that they show
anything useful in this case.
Exercise 5.4: Thermal Decay Neutron Example
The value of S w is 0.28.
If S shale is increased to 30, the value of S w becomes 0.20. If it is lowered
to 20, S w becomes 0.35. Therefore the uncertainty in S w resulting from the
uncertainty in S shale is ±8 s.u.
Exercise 5.5: Error Analysis
Based on the Monte-Carlo analyses, the following ranges are proposed
for the average properties for this well:
The exercise was performed on zone 2 only, with the saturation analy-
sis performed only over the oil-bearing part.
Parameter Mean s.d. Suggested Error
Net/gross 0.944 0.0049 ±0.01
Porosity 0.108 0.003 ±0.006
S w (Archie) 0.538 0.15 ±0.3
S w (cap curve) 0.532 0.014 ±0.03
