This paper presents an adaptive rationalized Haar function approximation method to obtain the optimal injection strategy for alkali-surfactant-polymer (ASP) flooding. In this process

the non-uniform control vector parameterization is introduced to convert original problem into a multistage optimization problem

in which a new normalized time variable is adopted on the combination of the subinterval length. Then the rationalized Haar function approximation method

in which an auxiliary function is introduced to dispose path constraints

is used to transform the multistage problem into a nonlinear programming. Furthermore

an adaptive strategy proposed on the basis of errors is adopted to regulate the order of Haar function vectors. Finally

the nonlinear programming for ASP flooding is solved by sequential quadratic programming. To illustrate the performance of proposed method

the experimental comparison method and control vector parameterization (CVP) method are introduced to optimize the original problem directly. By contrastive analysis of results

the accuracy and efficiency of proposed method are confirmed.