注二氧化碳置换天然气水合物反应速率常数二元线性预测方程

Binary linear prediction equation for the reaction rate constant of natural gas hydrate replacement with carbon dioxide injection

针对二氧化碳置换天然气水合物置换效率低、任意温度和压力下置换反应速率常数求取困难等问题,在填砂多孔介质中合成了水合物饱和度约为80%的实验样品,开展注二氧化碳定容置换与吞吐置换甲烷水合物实验。实验采用色谱分析确定置换过程中气样化学组分变化和置换率,基于化工热力学理论计算置换推动力,通过数据反演和多元线性回归建立置换反应速率常数的计算方程。结果发现,相同条件下,吞吐置换的置换率较定容置换平均提高45%,置换反应速率常数与温度和压力呈二元线性定量关系。基于此定量关系预测的置换反应速率与实验结果的误差小于5%,实现了任意温度和压力下置换反应速率常数的准确计算。

To solve the problems of low replacement efficiency of natural gas hydrates by carbon dioxide injection and difficulty in obtaining the replacement reaction rate constant at any temperature and pressure,hydrate samples with saturation of about 80%were synthesized indoors in porous medium,and replacement experiments for methane hydrate via carbon dioxide injection and replacement were conducted by constant volume and huff and puff.Chemical composition of gas sample and hydrate replacement ratio were determined by chromatographic analysis,and replacement driving forces were calculated by chemical thermodynamics theory,the calculation equation of the replacement reaction rate constant was established by using data inversion and multiple linear regression methods.Research has shown that the replacement ratio of huff and puff replacement is increased by 45%compared to constant volume replacement.The replacement reaction rate constant exhibits a binary linear quantitative relationship with temperature and pressure,and the error between the replacement reaction rate from the quantitative relationship and that from the experiments is less than 5%,which achieved accurate calculation of the replacement reaction rate constant at any temperature and pressure.