Predicting Production Temperature Using Tracer Methods

Abstract

Estimates of the thermal history of reinjected fluid are necessary to insure that power production and plant equipment performance can be maintained for the design lifetime of the heat recovery system. Uncertainty in the knowledge of the flow geometry may lead to significant error in the projected production temperature. Using a simple reservoir model, it can be shown that the length of time required for an injected fluid element to heat to a given temperature is independent of the streamline path taken by the fluid element. This rather general statement suggests that a knowledge of the distribution of fluid residence time between injection and production temperature history for reservoirs of which the model is applicable. The distribution of fluid residence time can be obtained using tracer standard methods. A general expression for the production temperature is obtained based on this observation and the assumption that the porosity thickness product, ¢h, is known or can be estimated.