基于分形理论的中国原油管道网络结构研究

Research on Structure of China's Crude Oil Pipeline Networks Based upon Fractal Theory

为深入分析全国及各区域原油管网的结构与布局,揭示其空间结构特征,论文运用分形理论的三种维数:加权长度-半径维数、分枝-半径维数和关联维数,分别从密度、连通性及通达性研究了全国及各区域原油管网。研究结果表明:全国原油管网的密度和连通性均存在明显的东西分异特征,密度自东向西呈"线状-散点"的下降形态,连通性自东向西呈"散点-线状"的升高形态,而通达性则普遍较低;对各区域来说,东北、华北和华东等东部管网除连通性较低外,其他分形指标相对较高;西北管网的密度、通达性均不如东部,而且其新疆管网的连通性数值超过2,是不正常的连通结构;华南管网的多数分形指标均低于其他地区,其管网结构雏形尚未形成。

By the end of 2008, about 90% of China＇ s crude oil transportation has been taken by pipeline, and it has been the primary way of China＇ s crude oil flow. So that it is important to deeply analyze the spatial structure of China＇ s national and regional crude oil pipeline networks. On the basis of a huge mass of reference materials, this paper examines three fractal dimensions, that is, weighted length-radius, dendrite-radius and spatial correlation, and then elaborates the influencing factors of this structure, including the distribution of networks＇ nodes and lines, the development of regional networks and others. In sum, the amended results reveal that： 1 ） As to national networks, the weighted length-radius dimension is characterized as linear distribution in the east while scattered distribution in the west, which reflects that the networks tend to cluster and the networks＇ density has become lower from the east to the west. Similarly,the dendrite-radius dimension changes from scatters to linear distribution from the east to the west, reflecting the networks＇ structure gets complicated and the connectivity is improved accordingly. Differed from two dimensions above, the dimension of spatial correlation expresses the whole scat- tered distribution, which reflects the general low accessibility. The reasons are as follows. First, the trunk of pipeline networks in East China have relatively developed, contrasting with the net- works in South China and West China. Second, there are evenly some isolated pipelines in East China＇s networks, which limit eastern networks＇ connectivity. Third, some nodes of national networks are not located at the trunk pipelines, resulting in general low accessibility. 2 ） As to regional networks, the overall distribution of density characteristics is similar to that of national networks, while the overall connectivity characteristic is different. Specifically, as to Xinjiang Region, its fractal dimension value of dendrite-radius is over 2, that is, its connectivity in the central part of the networks is lower than in the surrounding area, which is abnormal;the dimension value of dendrite-radius in Shanxi-Gansu-Ningxia networks is 1. 216, reflecting its con- nectivity is relatively good, compared with less than one in East China and null value in South China. Furthermore, as to the accessibility, all regions＇ dimension values of spatial correlation are less than one, but the spatial correlation in East China tends to be in linear distribution. The reasons are as follows. First, the indirect oil transportation pattern of oilfield A-oilfield B refin- eries in Xinjiang networks, increases the branches of networks, making it too complicated and limiting the connectivity of the networks. Second, the construction of pipeline networks in East China is lagging better than in other regions. Third, the construction of networks in South China is lagging behind other regions, thus its networks hasn＇t been shaping. 3） With the theory and methods of fractal, it could be effective to reflect the spatial structure and its distribution of China＇ s crude oil pipeline networks. In the future, it is necessary to further analyze the harmony or correction between fractal feature of regional pipeline networks and region- al oil production and consumption, then to reveal the interactive mechanism between them.