页岩甲烷高压等温吸附模型评价与改进  

Evaluation and improvement of high-pressure isothermal adsorption model for methane in shale

作　　者：董银涛 鞠斌山[1,2] 刘楠楠 DONG Yintao;JU Binshan;LIU Nannan(School of Energy Resources,China University of Geosciences(Beijing),Beijing 100083,China;Beijing Key Laboratory of Unconventional Natural Gas Geological Evaluation and Development Engineering,Beijing 100083,China;Coal Reservoir Laboratory of National Engineering Research Center of CBM Development & Utilization,China University of Geosciences(Beijing),Beijing 100083,China;CNOOC Research Institute,Beijing 100028,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]非常规天然气地质评价与开发工程北京市重点实验室,北京100083 [3]中国地质大学(北京)煤层气开发利用国家工程研究中心煤储层物性实验室,北京100083 [4]中海油研究总院,北京100028

出　　处：《煤炭学报》2020年第9期3208-3218,共11页Journal of China Coal Society

基　　金：国家重大科技专项资助项目(2016ZX05011-002,2017ZX05009-005)。

摘　　要：为确定合理的页岩甲烷高压等温吸附模型,以准确拟合实测过剩吸附量曲线,并计算其绝对吸附量曲线。选取常用的8种吸附公式及3种吸附相密度计算方法,分别组成高压等温吸附模型,并以过剩吸附量的拟合度R2、绝对吸附量校正的合理性、吸附相密度计算的合理性以及吸附理论选择的合理性为考核指标,分别采用333与363 K温度条件下共18组实测值对其进行定量评价。推导了吸附相密度关于压力与温度的函数,并组合使用Langmuir-Freundlich与Dubinin-Radushkevich吸附公式,构建了改进的高压等温吸附模型。结果表明:在3种吸附相密度计算方法中,拟合吸附相密度法最佳,该方法结合Langmuir-Freundlich或Dubinin-Radushkevich吸附公式构成的吸附模型最准确,其拟合过剩吸附量的R2平均值分别为0.9983和0.9978;给定吸附相密度法构成的吸附模型对过剩吸附量的拟合度较低;而过剩吸附量与气体密度曲线计算吸附相密度法的准确性较差。改进模型对18组实测过剩吸附量的拟合度R2平均值为0.9969;计算绝对吸附量的偏差为0.087,优于现有模型;且其具有物理基础,符合页岩甲烷吸附机理。This study aims to fit experimental excess adsorbance and calculate absolute adsorbance accurately by determining the reasonable high-pressure isothermal adsorption model for methane in shale.Eight adsorption formulations and three adsorption phase density calculation methods were chosen for setting up the high-pressure isothermal adsorption model.The goodness of fitting(R2)for excess adsorbance,the rationality of absolute adsorbance correction,the rationality of adsorption phase density calculation,and the rationality of the choice of adsorption theories were chosen as evaluation indexes.Thereafter,a total of 18 sets of experimental data at 333 K and 363 K were used to quantitatively evaluate the models,respectively.Moreover,the function of the adsorption phase’s density related to pressure and temperature was derived,and the adsorption formulas of Langmuir-Freundlich and Dubinin-Radushkevich were combined.Then,an improved high-pressure isothermal adsorption model of methane in shale was proposed.The results show that the fitting density method of the adsorption phase is the best method among the three calculation methods of adsorption phase density.Combining this method with Langmuir-Freundlich or Dubinin-Radushkevich adsorption formulas,the currently most accurate high-pressure isothermal adsorption models can be obtained,which the R2 to the excess adsorbance are 0.9983 and 0.9978,respectively.However,the adsorption model composed by the given adsorption phase density method has a low R2 to the excess adsorbance.The accuracy of the method for calculating the adsorption phase density based on the relation of excess adsorbance and gas density is poor.Furthermore,the average R2 of the 18 groups’excess adsorbance fitted by the improved model in this paper is 0.9969.Its calculated deviation of the absolute adsorbance is 0.087,which is better than the existing model.Thus,the improved model in this paper has a physical basis and is consistent with the adsorption mechanism of methane in shale,which can provide the

关 键 词：页岩气 高压 等温吸附 过剩吸附 吸附模型 

分 类 号：P618.13[天文地球—矿床学]