Page 246 - Well Logging and Formation Evaluation

236 Well Logging and Formation Evaluation

CHAPTER 7: ROCK MECHANICS ISSUES

Exercise 7.1: Net Effective Stress

Ignoring the poroelastic constant the uniaxial stress should be:

,
*
=
.
,
12 000 psi - 12 000 0 435 6780 psi .
The conversion from uniaxial to isostatic is given by:
.
+
.
Isostatic uniaxial = (1 0 35 ) (3* (1 - 0 35 )) = 0 692.
Hence the experiments should be performed at 0.692*6780 = 4693psi.
If the poroelastic constant is 0.85 the true effective stress is given by:

.
* (
,
*
.
12 000 0 85 12 000 0 435) = 7563 psi .
-
,
The experiments should be performed at 0.692*7563 = 5234psi.
CHAPTER 8: VALUE OF INFORMATION
Exercise 8.1: Decision Tree Analysis

The following decision tree should be used to establish the EMV of
running the tool:

Yes Do nothing

Yes Zone flushed?
No
Yes Recomplete:
–$M0.02 Tool reliable? +$M1.4
No Yes Recomplete:
TDN?
–$M2.2
Zone flushed?
No
No
Do nothing

Do nothing