Optimization of Surface Systems in Mature Oilfields with High Water Content

This paper investigates the optimization and renovation of surface systems in mature oilfields. To address challenges such as facility load imbalance, low operational efficiency, excessive energy consumption, and high operational costs due to high water content in produced fluids, we developed a coordinated optimization model for the gathering and injection systems. The objective of the proposed optimization scheme is to minimize renovation investment and operating costs. The model comprehensively considers constraints such as equipment energy consumption costs, topology changes, facility load rates, and the hydraulic and thermal conditions of the pipeline network to achieve the optimal renovation and enhancement of the gathering and injection systems in mature oilfields. The model uses pre-water separation devices at oil transfer stations to separate part of the water phase, reducing energy consumption during the transportation of high water cut production fluids and decreasing the load on subsequent processing facilities, achieving energy conservation, consumption reduction, and load balancing in the surface system. The study is validated using real data from an oilfield in Northwest China. The results show that the optimized gathering and water injection system can reduce annual operating costs by 14.27 million CNY (a decrease of 10.4%) and annual carbon emissions by 1.476×103 t (a decrease of 9.3%). The total investment for the renovation is 51.35 million CNY, with a significant economic benefit, resulting in a payback period of 3.59 years. The study demonstrates that through optimization and renovation, the energy consumption and operating costs of surface systems in mature oilfields can be significantly reduced, improving system operational efficiency and offering high economic and environmental benefits.