At present only the influence of free-gas to the pump efficiency was considered in the simulation of system efficiency of rod-pumped well, the energy of it released was overlooked, resulting in the simulation precision of system efficiency in high-GOR wells was low. Aiming at this phenomenon, a new theory was raised that the gas of the layer released energy in the lifting process including two parts: dissolved-gas expansion energy and free-gas expansion energy. The motor's input power of rod pumping system was divided into hydraulic horse power, gas expansion power, surface mechanical loss power, down-hole viscous friction loss power and down-hole sliding friction loss power. Using the theory of energy-conserving, the simulation model of free-gas expansion power was established, the simulating models of the motor's input power which were based on the energy method were improved and the simulation precision of system efficiency was enhanced. The simulation examples indicated that the free-gas expansion power can't be overlooked when calculating the input power and the new simulation models of system efficiency had higher simulation precision.
展开▼
