Sensitivity analysis and optimal operation control for large-scale waterflooding pipeline network of oilfield

Waterflooding development is one of the most common methods in oilfields. The energy consumption of waterflooding system accounts for a large proportion of the total in oilfield development. Therefore, the optimization of waterflooding system is able to further decrease operation cost and enhance development efficiency. But it is complicated to optimize operation control of large-scale waterflooding pipeline networks as a result of lots of wells and complex waterflooding pipeline networks. Although previous scholars have done much research, few have considered technical constraints of waterflooding networks. This paper puts forward a quantitative evaluation approach to pressure and flowrate sensitivity of waterflooding pipeline networks firstly, and concludes that the pressure and flowrate sensitivity are related to network topological structures, pipeline parameters and current operation flowrates. Meanwhile, an operation optimization approach to large-scale oilfield waterflooding system based on mixed integer linear programming (MILP) is proposed, which considers pump characteristic curves, adopts Hazen-William formula to simulate hydraulic pressure drop of pipe segments and deals with nonlinear items by phased linearization method. With the demand flowrate, the optimal pumping scheme of waterflooding station, pumping flowrate and throttling pressure of each well can be efficiently worked out. Finally, this approach is successfully applied to a virtual waterflooding system with 15 wells and a large-scale real one with 82 wells in China. Results show that the model has better practicality for the operation control optimization of waterflooding pipeline networks with larger scale and stronger sensitivity.