Research On Chance Constrained Programming Of Chemical Flooding For Enhanced Oil Recovery

Chemical flooding is an important class of enhanced oil recovery technologies in tertiary oil recovery phase,including single chemical flooding and combination flooding.However,chemical agent is expensive and the oil price and reservoir geologic parameters are uncertain in the complex and time-consuming development process.In order to design the development schemes scientifically and gain as much reward as possible,this paper studies the optimization problems of injection strategy for chemical flooding with uncertainties.For the shortcomings of the standard spiral optimization algorithm,a novel hybrid spiral optimization(HSO)algorithm is proposed.The mutation operation is introduced into the standard algorithm,as which the location update operation of backbone particle swarm optimization is treated.While keeping the global search ability of original algorithm,the hybrid algorithm also enhances the local optimization performance so that the solving precision and efficiency are improved.As to general constrained optimization problem,it can be transformed into unconstrained optimization problem by using the penalty function method with unfixed piecewise mapping.This method can avoid the difficulty of determining the penalty coefficient in the traditional method.Some standard testing examples show that the hybrid algorithm has a good performance.Then the HSO is applied into the optimal control problem of CSTR and optimization problem of one-dimensional polymer flooding.And the results verify the effectiveness of the proposed algorithm.As to chemical flooding,the optimization problem of injection strategy is studied.Considering the uncertainties of crude oil price and the geologic parameters,and aiming to gain the maximize profits or oil production,the chance constrained programming models of polymer flooding with uncertainties are established,respectively.According to the characteristics of uncertainties in the models,the certainty equivalent transformation and stochastic simulation method are used to deal with the chance constraints,respectively.Then the HSO is applied to solve the problems.The results of some application cases prove the feasibility and effectiveness of this method.In chemical combination flooding,the chromatographic separation phenomenon can reduce or even destroy the displacement efficiency.Through using a new model for distinguishing the phenomenon,the calculation method of chromatographic separation parameter is designed.Then a visual software for calculating the parameter is developed by using object-oriented programming method.In order to maximize the synergy of combination system as far as possible,and considering the uncertainties of the geologic parameters,an uncertain optimization model of chemical combination flooding is established by using chance constrained programming.Then an application case is also solved by this method.