N_2、CO_2和天然气在岩心孔隙内表面的吸附量的测定

EXPERIMENTS FOR MEASURING ABSOLUTE ADSORPTION OF N_2,CO_2 AND NATURAL GAS ON CORES

利用高精度孔隙度测定仪和气相色谱分析仪 ,采用恒体积法 ,测定了室温 ( 2 83～ 2 92 K)、低压 ( 0 .1 67～ 0 .3MPa)下N2 、CO2 和天然气在 8个不同的岩心孔隙内表面的吸附量 ,对于天然气 ,还测定了吸附前后自由气体的摩尔组成 ,被吸附气体 (吸附相 )的摩尔组成和天然气各组分的相对吸附量。实验结果表明 :用 N2 测得的吸附气量在原始气中所占的比例为0 .4 %～ 4 %不等 ,CO2 的为 1 %～ 5%不等 ,天然气的为 3%～ 6%不等 ;吸附前后自由天然气的摩尔组成有显著的差异 ,表明岩心对天然气有明显的吸附 ;天然气各组分间存在竞争吸附 ,重质组分的相对吸附量大于轻质组分。

Study on adsorption in porous media of reservoir is very important for phase equilibrium calculation of condensate gas and the right way of insight at the gas or condensate gas reservoir.In this paper,experiments for measuring absolute adsorption of N 2, CO 2 and natural gas on 8 different artificial cores using an accurate porosimeter and an precise chromatographic instrument under room temperature (283～292°K) and low pressure (0 167～0 3MPa) have been studied.From these experiments,the following results can be obtained:i.The proportion of the N 2 adsorbed and that imported into the equipment is about 0.4%～4 0%,and that of CO 2 is 1%～5% and natural gas is about 3%～6%;ii.The mole composition between the bulk phase of natural gas after adsorption equilibrium and the original natural gas is different,which is the proof of artificial cores has a obvious adsorption ability to the natural gas; iii. The adsorption capacity of heavy composition of natural gas is more than that of light one.