The Design of Binary Cycle Heat Exchange System With Forced Convection For Horizontal Well

In order to realize the goal of rapid heat resupply of reservoir fluid near the wellbore area during geothermal development, a binary cycle heat exchange system with downhole forced convection is designed in this paper. During production, the weak natural convection of the reservoir fluid is changed into an adjustable forced convection, which can greatly improve the heat exchange efficiency. The inner loop of working fluid and the forced convection cycle of reservoir fluid are independent of each other, which conforms to the principle of "Zero Mass Withdrawal". Main results show that: a) The design of two completion intervals have provided cycle channels for the reservoir fluid to flow in-and-out of the casing annulus, and the downhole power unit provides power for the forced convection cycle to achieve the rapid heat resupply of heat reservoir near the wellbore area. b) The feasibility of this system is demonstrated by finite element analysis, and the simulation shows that the temperature of downhole node under the condition of 200m3/d with forced convection is always 6~8℃ higher than that without forced convection. c) Considering geologic and engineering conditions, the optimization of downhole power unit is carried out, and it is recommended to use electric submersible pump. d) A detailed engineering design for running string and tools is proposed.