Research on coupled model and parameter optimization of dual-ESP pumping system

In this paper, dual-ESP coupled lifting technology was developed to break through the upper limit of single-ESP lifting capacity so as to satisfy the requirements of deep well exploitation and make full use of the potential capacity of oil and gas wells suf ficiently. By virtue of this technology, the dual-ESP lifting capacity is applied suf fi ciently based on the coordination of double electric submersible pumps. Then, a mathematical model for the coupling relationship of dual-ESP oil pumping was established after the kinematics, kinetic characteristics and coupling relationships of oil reservoir in flow performance, borehole multiphase flow and lifting technology were investigated. By means of nodal analysis method, the dual-ESP operation parameters for the supply-discharge coordination of oil wells were solved with the maximization of system efficiency and production rate as the target. And accordingly, the parameter design software for dual-ESP coupled lifting technology was prepared. And finally, a case calculation was conducted to compare the dual-ESP relay lifting system and the single-ESP pumping system from aspects of pump stage amount, pump power, system efficiency and maximum liquid production rate. It is indicated that dual-ESP lifting decreases the single-ESP lifting pressure, and consequently decreases the pump stage amount and the pump power and improve the system efficiency. And it can make full use of the lifting capacity of two electric pumps to increase the production rate of oil wells and exert the potential capacity of oil wells suf fi ciently. It is theoretically signi fi cant to the dual-ESP type selection and design for the exploitation of deep wells.