Methods for Dispatching and Optimization of Economic Operation of Water Injection System of Large-Scale Oilfield

The water injection system of large-scale oilfield is a very complicated pressure system, which consists of several water injection stations connecting with each other. At present, the system suffers a couple of prevailing problems, for example, low injection efficiency and high power consumption, and the dispatching and optimization of the system operation serves as an important approach to solve such problems. The mathematical model for optimization of operation scheme of the oilfield´s water injection system is established with the minimum power consumption of water injection as the objective function, and the restriction on hydraulic balance, water injection rate and water injection pressure as the constraint conditions. The model belongs to a hybrid optimization design with discrete and continuous variables. In accordance with the structural characteristics of the model, the solving strategy based on the hybrid genetic algorithm is worked out; meanwhile, the methods for selection, chiasma and mutation of chromosome are put forward, and the corresponding software is also programmed. This method is adopted to make the optimization calculation for the operation scheme of high-pressure water injection system of certain oilfield, showing that the unit power consumption of water injection is reduced by 0.291 kW-h/m³, with the power saved totaling 6.76 times 10⁶ kWldrh/a.