Optimization of mixing transportation process for capacity enhancement of Lanzhou–Chengdu crude oil pipeline

Objective With the rapid growth in demand for Changqing crude oil by PetroChina Sichuan Petrochemical, the existing process of mixing transportation via the Lanzhou–Chengdu crude oil pipeline is facing significant challenges. Moreover, the mixing transportation process in the Lanzhou–Chengdu crude oil pipeline is highly complex, and merely adjusting blending proportions can hardly provide an adequate solution.

Methods This paper systematically analyzes the current status of mixing transportation along the Lanzhou–Chengdu crude oil pipeline and examines the key factors that restrict further improvements in blending capacity. These factors primarily include variations in the physical properties of oil products, an increased tendency for wax deposition, and greater challenges in restarting the pipeline after shutdown. Drawing on extensive operational data and blending ratio experiments, this paper elaborates on an optimization strategy for year-round mixing transportation of this crude oil pipeline. It focuses on specific measures such as solidification point control for mixed oil products, blending proportion optimization, stirring process improvement, and pigging efficiency enhancement. Furthermore, a detailed optimization solution is proposed. Additionally, this paper explores the potential for maximizing blending capacity while ensuring safe operation, providing a scientific demonstration of the safety of the heated transportation process and the restart strategy after shutdown.

Results The potential impact of mixing transportation for capacity increase on pipeline operational safety was thoroughly evaluated. By predicting annual throughputs and fine-tuning blending proportions, the maximum theoretical boundary for annual capacities of mixing transportation with Changqing crude oil was calculated to be 300×10⁴ t. The results of this study provide essential data to support the actual operational management of the Lanzhou–Chengdu crude oil pipeline.

Conclusion The study results not only facilitate significantly improving the operational efficiency and capacity of the Lanzhou–Chengdu crude oil pipeline, but also provide valuable practical experience and a theoretical basis for the development of future mixing transportation plans.