The Experimental Research on the Reduction of Heat Loss Rate of Wellbores with two-Phase Closed Thermosyphon Wellbore

Abstract

In order to compare heat losses of the wellbore fluids in a two-phase closed thermosyphon wellbore with that of the conventional wellbore during the flow process, different conditions of heat losses of fluid flow in wellbore have been compared with each other firstly. Through laboratory experiments, heat losses of the wellbore fluids in a two-phase closed thermosyphon wellbore have been measured to analyze influences to the heat loss caused by factors like working medium, filling ratio, vacuum degree, temperature and flow rate of the simulation oil. According to the results, a two-phase closed thermosyphon wellbore is helpful in the reduction of heat loss of wellbore fluids, different working media influence the heat loss rate differently and under different temperatures of simulation oil, there is a working medium for the lowest heat loss rate respectively. Freon is the working medium when the temperature of the simulation oil is 50°C, methanol for 70°C and distilled water for 90°C the heat loss rate of the wellbore fluids in two-phase closed thermosyphon wellbore decreases first and then increases as the filling ratio goes up. The heat loss rate reaches the minimum when the filling ratio is 15%; heat loss rate also increases as the temperature of the simulation oil increases and decreases as the flow rate of oil goes up. However, it has a similar heat loss rate with that of conventional wellbore fluids as the flow rate increases to a certain amount.