考虑垫底气回收价值及资金时间价值的盐穴型地下储气库储气费计算方法

我国的地下储气库(以下简称储气库)与油气管道捆绑运营,没有单独的定价机制,计算储气库储气费时也未充分考虑资金的时间价值及油气藏型、盐穴型储气库垫底气的回收价值,导致计算结果的准确性欠佳。未来储气库实行独立、市场化运营是必然趋势,因而需要建立一种符合我国储气库运营模式的储气费定价机制。为此,以国内某盐穴型储气库建设投资项目为例,采用二分法建立了一种考虑垫底气可回收的储气费计算模型,计算出该储气库在不同内部收益率下的储气费,并分析了影响储气费的主要因素。结果表明:(1)当储气费为1.02元/m~3时,可满足内部收益率8%的要求;(2)在盐穴储气库工作气量确定的情况下,年储转次数(储气库年实际注采气量与年设计工作气量的比值)是影响储气费的最重要因素,地下及地面工程等建设投资的影响次之,而经营成本的影响最小;(3)在储转次数大于1.4时,盐穴储气库注采运行的工作效率达到最大,建议将盐穴储气库的储转次数设定为1.4。结论认为:该储气费计算方法在保证能获得一定利润的前提下,充分考虑了资金的时间价值以及垫底气的回收价值,计算得到的储气费较为合理,可推广到类似盐穴型储气库的应用计算。

A methodology for calculating the gas storing price of salt cavern UGSs considering the recycle value of cushion gas and the time value of capital

At present, domestic underground gas storages (UGSs) is treated only as an auxiliary facility of oil and gas pipeline companies without an independent pricing system. And when its gas storing price is calculated, the recycle value of cushion gas of oil/gas reservoir UGSs and salt cavern UGSs and the time value of capital are not taken into full consideration, so its calculation accuracy is not good enough. Independent and market-oriented operation is the inevitable development trend of UGSs in the future, so it is necessary to establish a gas storing pricing system suitable for domestic UGS operation mode. In this paper, the construction investment project of one salt cavern UGS in China was taken as the research object. A gas storing price calculating model considering the recycle of cushion gas was established by the dichotomy method. Then, the gas storing price of this case UGS under different internal rates of return (IRR) was calculated and the main factors influencing the gas storing price were analyzed. And the following research results were obtained. First, the IRR of 8% can be satisfied when the gas storing price is CNY 1.02 per m3. Second, when the working gas volume of a salt cavern UGS is determined, annual storage–withdrawal frequency (the ratio between the actual and designed annual working gas volume) is the most important factor influencing gas storing price, and the construction investment of underground and ground engineering takes the second place, while the effect of operation cost is the least. Third, the working efficiency of a salt cavern UGS is the maximum when the storage–withdrawal frequency is over 1.4, the value of which is thus recommended here. In conclusion, this gas storing price calculating method takes full consideration of the time value of capital and the recycle valve of cushion gas while ensuring a certain profit, so its calculation result is more reasonable. This method shall be popularized and applied to the calculation of similar salt cavern UGSs.