Abstract: The rule of energy exchange correspondence of molecular thermal vibrations of fiber optic and photon interaction is principle of fiber optic distributed temperature sensing operation. The examples of the fiber optic distributed temperature system （FODTS）applications of a heavy oil horizontal well group in Liaohe Oilfield outlines the basics and installation of the system, and the results of system test temperature profile is analyzed. The hot interwell communication is divided into two phases, i.e. thermal fluid connectivity and steam breakthrough. Results show that the efficiency of thermal fluid connectivity has reached 36.7% of horizontal length after this round injection and hot inter well communication hasn′t accessed steam breakthrough phase. The reservoir properties have a big influence on heat transfer before thermal fluid connectivity phase. The integrated interpretation of hot interwell communication and well log is used for heated reservoir performance completely and objectively.

Key words: fiber optic, temperature, hot inter well communication, heavy oil, steam injection