Determination of static reservoir temperature from transient data following mud circulation

The current method for estimating the static reservoir temperature from transient data, gathered downhole after the cessation of mud circulation, is a Horner-type approach. Reservoir temperature so established generally turns out to be a lower estimate of the true temperature. This work shows that the temperature analog of the Horner method is limited to large circulation time situations and is not applicable to cases where the mud circulation time is generally short (less than 30 hours). This study provides a general solution of the thermal diffusivity equation obtained with an appropriate inner-boundary condition to solve the early-time, transient heat transfer problem. An analytical solution was developed to handle problems requiring a variable-rate heat transfer or the superposition effects. A simple graphical technique is used to interpret data by using the superposition function. Three approximate solutions, reflecting different time domains, are also presented. These solutions are quite reliable as long as they are applied within the specified time bounds. Synthetic examples are used to validate the proposed method, and field examples from both oil and geothermal wells demonstrate its application.

Determination of static reservoir temperature from transient data following mud circulation Conference Paper