用普通累积法预测油气管道投资

Predicting the Investment in Oil and Gas Pipelines by the Ordinary Cummulative Method

文献 [1]用灰色系统方法预测油气管道投资费 ,其计算步骤较多 ,计算繁琐。文章采用计量经济学中的新方法———普通累积法预测管道投资费。该方法与文章建立的二次曲线模型既可拟合历史管道投资费 ,又可预测建设期的管道投资费 ,计算方法比灰色预测更简捷。预测结果与灰色预测结果比较 ,相对误差仅为 1.5 2 4%。为进一步验证用普通累积法预测管道投资费的可靠性与准确性 ,对价格指数的时间序列分 3种情况进行了数据拟合和事后预测 ,其拟合值、预测值与实际值的相对误差均小于 5 % ,平均绝对误差均小于 1.6 85 % ,其预测值与灰色预测值的相对误差均小于 2 .42 8% ,证明该方法和文章建立的二次曲线模型能较准确地反映价格指数的变化规律 ,是价格指数和管道投资预测方法的扩充。文中还对文献 [1]建立的 4个管道投资费的管径、壁厚回归模型作了改进 ,扩充至 6个回归模型 ,以便在拟合的管径、壁厚范围内其管道投资费都可以计算。同时 ,还强调了预测与计算中应注意的两个问题。

It is quite complicated with so many steps if a grey system method is used to predict the output in oil and gas pipelines as in the literature .A new econometric method-the ordinary cummulative method,simpler and quicker than the grey system method, is adopted to forecast how much it will be cost upon the pipelines.The build up quadratic curve matched with this new approach can not only represent a view on the pipelines investment in the past but also calculate in advance the investment put into the pipelines during the whole construction.Compared the result obtained from the gray system method,the relative error of this new method is only 1.524%.In order to guarantee its reliability and accuracy,the time series of price indexes are classified into three cases in each of which data is to be matched and predicting work is to be done after the event. Compared with the actual values,the relative error of the matching and predicting values are all less than 5%;the average absolute errors are all less than 1.685%.Compared with the gray predicting values,the relative error of the predicting values are all less than 2.428%.It is proved that this new method with the newly build up quadratic curve can reflect in a right way the regular variables of the price index.The previous four regression models on pipe diameter and pipe wall thickness,seen as in the literature ,is modified and added up to six regression models so as to calculate the pipeline output values within the range of the matched pipe diameter and pipe wall thickness.Meanwhile,it is emphasized that two problems ought to be paid much attention to in predicting and calculating work.