Improving Water Injection Efficiency in Oil Fields With a Novel Multiperiod and Mixed Transport Optimization Model

Summary Water injection oil recovery is a necessary method to maintain production pressure by injecting water into the reservoir to replenish the reservoir energy. It also utilizes the water-driven effect to enhance the macroscopic sweep efficiency and microscopic displacement efficiency of crude oil, thereby achieving secondary oil recovery in the oil field and increasing the ultimate recovery rate. Water injection is a key method for improving oilfield recovery, and its energy consumption is linked to the injection scheme. Conventional water injection systems (CWIS) often operate based on the highest well pressures, leading to significant throttling losses. Additionally, when a station’s injection capacity is below demand, some wells may not operate properly, reducing oil recovery efficiency. To address these issues, this study introduces a novel multiperiod mixed transport water injection (MPMT) model. When the water supply is insufficient, trucks transport water from an intake point to wells, categorizing wells into three pressure groups: low, medium, and high. The injection process is divided into three periods corresponding to these groups. The study establishes the MPMT model, differentiated into fixed intake point (FP) and nonfixed intake point (NFP) for trucks. Optimization results show that adopting the MPMT model reduces total energy costs by 5,000–6,000 CNY/D compared with not using it, while the MPMT-NFP model saves about 1,500 CNY/D compared with the MPMT-FP model. Thus, using the MPMT-NFP model leads to significant energy savings and cost reductions in oil fields.