BAKER HUGHES - Drilling Fluids Reference Manual

PRESSURE PREDICTION AND CONTROL
increased pore pressures present in shale which is an indicator of underlying higher pressure
formations.
Depth, ft
Interval Transit Time, μ sec/ft
ELECTRIC LOG ANALYSIS
Figure 12 - 3 Interval Transit Time
Abnormally pressured zones can be predicted by analyzing changes in shale conductivity
recorded on induction logs. Steps in the procedure are:
1. Obtain shale conductivity (C s ) readings from an induction log.
2. Make a plot of C s vs. depth on semi-log paper.
3. Draw the best straight line through the shale conductivity plot.
4. A sharp change in direction by some of the plotted points generally indicates the
presence of an abnormal pressure zone.
5. Record the ratio of shale conductivity observed to normal conductivity of that shale
(see Figure 12-4).
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 12-5