高温高压下多种气体在储层岩心中吸附等温线的测定

利用自行研制的XF1型高温高压气体吸脱附测试仪,结合一台色谱分析仪(HP6890),一套抽真空系统,分别测定了N₂、CH₄、C₂H₆、C₃H₈、nC₄及其混合气体在三个岩心中的吸脱附等温线共计42条(单组分30条,累计测试点516个;混合气12条,累计测试点203个),以及吸附平衡后混合气的自由气相组成、吸附相组成和各组分的吸附等温线各48条(累计测试点431个).测试的温度为50.5℃.实验结果表明:①储层岩心介质对烃类气体的吸附现象是客观存在的,不容忽视;②仅就测试所得的数据来看,如果忽略其它因素,可以初步估计,不考虑吸附的砂岩储层气藏的计算储量将比考虑吸附少5%以上;③岩心-气体吸附体系的吸附能力除受压力影响外,更受到储层介质、岩石成分、结构和物性性质的影响,除此之外,还受到多组分气体中重烃组分数目、摩尔含量等的影响;④多组分气体组分相对吸附量能有效地表征多组分气体中各组分气体的竞争吸附能力大小,依据这个指标可将五元多组分气体体系中各组分气体按其竞争吸附能力由强到弱排序为nC₄>C₃H₈>C₂H₆>CH₄>N₂.

EXPERIMENTAL DETERMINATION OF ADSORPTION ISOTHERMS OF GASES IN THREE RESERVOIR CORES

The study on Reservoir Cores Adsorption Isotherms Using Paraffinic Hydrocarbons is a theme which is of difficult,but of practical and theoretical values,and which also is the foundation of the study on the laws of phase behavior and percolation of gas condensate system in real gas reservoir porous media.The contents of this paper, which are scarcely reported up to now in literatures,are one part of the theme.In this paper adsorption isotherms of N₂, CH₄, C₂H₆, C₃H₈, nC₄H₁₀ and the quinary (N₂-CH₄-C₂H₆-C₃H₈-nC₄) hydrocarbon mixtures in three reservoir cores named R1,T1and T2at temperature to 323.65 and pressure to 8.12MPa are measured by volumetric method.Forty-two adsorption isotherms with 516 measure points,data of mole percent of component of gas and adsorbed phase after adsorption equilibrium with 431 measure points,are obtained.The results of these experiments indicate:(1)the fact that hydrocarbons will be adsorbed by reservoir porous medium can’t be neglected in a real gas reservoir;(2)more than 5 percent of reserves in a real gas reservoir would have been adsorbed only estimated from the measured absorbance;(3)the adsorption capacity of reservoir porous medium is limited by its own pore structure,rock composition, specific surface,and also by the number and mole percent of heavy ydrocarbon component; and (4)according to adsorption capacity of each component in the quinary hydrocarbon mixtures,from strong to weak,it is nC₄H₁₀>C₃H₈>C₂H₆>CH₄>N₂.