A study of water curtain parameters of underground oil storage caverns using time series monitoring and numerical simulation

Abstract

Water curtain systems (WCSs) are key components for the operation of underground oil storage caverns (UOSCs) and their optimization and design are important areas of research. Based on the time series monitoring of the first large-scale underground water-sealed storage cavern project in China, and on finite element analysis, this study explores the optimum design criteria for WCSs in water-sealed oil caverns. It shows that the optimal hole spacing of the WCS for this underground storage cavern is 10 m in order to ensure seal effectiveness. When the WCS is designed with a 10-m horizontal hole spacing and a water curtain pressure (WCP) of 80 kPa, a water curtain hole (WCH) has an influence radius of approximately 25 m. The smaller the vertical distance is between a WCH and the main cavern, the greater the water inflow into the main cavern. The vertical hydraulic gradient criterion can be satisfied when this distance is 25 m. It shows that the optimal WCP is 70 kPa, which meets sealing requirements.

概要

目的

地下水封石油洞库的水封性至关重要。水幕系统适用于地下水补给匮乏、稳定地下水位较低的地区,其性能取决于水幕参数的选择。不同参数(水幕孔间距、水幕孔与洞室高度差和水幕压力等)的水幕系统对洞室的水密性和稳定性有不同的影响。目前,地下油库的水幕系统设计还不够合理,亟需优化,但设计依据仍不足。本文希望通过对水幕系统参数的研究,为实际工程应用提供一些参考。

创新点

1. 通过现场渗压监测和气压监测,建立地下油库运营评价体系,及时了解运营状况;2. 通过有限元计算,对比不同水幕参数的优劣性,获得水幕参数的优化方案。

方法

1. 结合地质勘探资料,探讨水幕孔布孔方式的依据;2. 通过收集现场监测时间序列数据,采用时序分析法评价运营期间地下水封储油库的运营和水封效果,讨论可能出现的渗漏或过量涌水情况;3. 通过有限元仿真模拟,选择水幕系统的三个关键参数并进行优化,评价提出的水幕参数效益,提出适用于本项目的最优参数解。

结论

1. 黄岛地下水封石油洞库项目水幕系统最佳水幕孔间距为10 m,最合理的水幕孔与洞室高度差为25 m,最优水幕压力为70 kPa。2. 当水幕孔间距大于10 m时,水封效果提升不明显;考虑到经济成本(建设、运行和排水成本),这种改进是无效的。3. 当水幕孔与主洞的垂直距离为30~35 m时,水封失效;目前水幕系统的垂直影响范围约为25 m。4. 受地形因素的影响,主洞室周围的孔隙水压力存在显著差异;当水幕压力为60 kPa时,垂直水力梯度小于1。