Temperature Logging - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 111

(c) Above the production point, the temperature rises, crosses the geothermal, and
approaches an asymptote offset ∆ T above the geothermal.
Two traces are shown on Fig. 8.8 —one for a high-permeability formation and
one for a low-permeability formation. Note that the initial cooling effect at the point
of production is less for the high-permeability formation than for the low.
Fig. 8.8 Gas-production temperature profiles. Courtesy Schlumberger
Water Injection
Figure 8.9 illustrates the temperature profiles to be expected in a water-injection
well. Things to note are:
(a) Depending on the temperature of the injected water relative to the undisturbed
formation temperature, the temperature profile above the injection point may
show an increase or a decrease with depth.
(b) At the injection point, the temperature profile is horizontal.
(c) Below the injection point, the temperature profile returns to geothermal.