Temperature Logging - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 104

Fig. 8.2 Typical temperature
log. Courtesy Schlumberger

Fundamentals

Undisturbed formation temperature increases predictably with depth. This increase
in temperature with depth is known as the geothermal gradient ( G ) and is usually in
the range of 1-2 °F per 100 ft. Figure 8.3 is a useful guide to geothermal gradients—
the temperature at any depth may be extrapolated using the relationship.

TT G
form

=+ •. depth

surf