基于API重度实现原油质量和体积的精确换算

Accurate Conversion of Crude Oil Mass and Volume Based on API Gravity

原油20℃的密度在700~1000kg/m^(3),一种原油在不同温度下的密度变化为非线性分布。因此质量和体积的换算方法复杂。标准方法利用密度和温度两个参数,借助石油计量表并代入公式完成换算,不仅步骤繁琐,且中间计算过程由于多次修约造成精度的下降并引入误差。原油的API重度带有温度和密度的双重信息,研究其定义并对原油质量和体积换算建立推导公式,把温度和密度两个参数替换为API重度一个参数,使换算公式更加简洁;考虑空气浮力修正,使换算完全按照标准的要求,精度优于石油计量表中的吨/美桶换算系数,公式尽可能保留有效数字,消除了连续修约引入的误差。该方法应用在原油计量中不仅达到了快速计算,而且适合期货原油的交割换算。

The density of crude oil at 20℃is between 700 kg/m3 and 1000 kg/m^(3),and the density change of a crude oil at different tem-peratures is non-linear distribution.Therefore,the conversion method of mass and volume is complex.The standard method uses two pa-rameters of density and temperature to complete the conversion with the help of the oil metering table and the formula,which is not only cumbersome,but also reduces the accuracy and introduces errors due to multiple rounding in the intermediate calculation process.The API gravity of crude oil contains dual information of temperature and density,so studying its definition and establishing a deduction for-mula for the conversion of crude oil mass and volume,and then replacing two parameters of temperature and density with one parameter of API gravity can make the conversion formula more concise.Considering the air buoyancy correction,making the conversion meet the requirements of the standard completely,the accuracy is better than the ton barrel conversion coefficient in the oil metering table.Be-sides,the formula should retain valid figures as far as possible,which can eliminate the error introduced by continuous rounding.This method applied in the crude oil metering can not only obtain the rapid calculation,but also be suitable for the delivery conversion of for-ward crude oil.