Abstract: In view of the fact that the constant steam injection rate of steam flooding is poor，an oscillatory steam injection rate optimization method of steam flooding based on improved PSO ( Particle Swarm Optimization) algorithm is proposed． Firstly，a mathematical model of steam injection rate of steam flooding is established． Then，the IPSO algorithm is used to solve the model and optimize of the oscillatory steam injection rate． Finally，the oscillatory steam injection rate optimization scheme of steam flooding is obtained．In the IPSO algorithm，we introduce chaos optimization operator to generate initial solutions and apply the self-adaptive mutation of particles according to the distance of the fitness of each particle． We adopt extreme disturbance on the individual history optimal values and global optimal value． It can speed up the convergence speed and increase the evolving ability of the population． The experimental results show that the established model is accurate and the optimization algorithm is effective． The proposed methodology can make steam flooding injection-production scheme more reasonable，ultimately contributing to its efficient operation．

Key words: particle swarm optimization ( PSO) algorithm, steam flooding, oscillatory steam injection rate, selfadaptive mutation, extreme disturbance