非烃气体置换CH4水合物的实验研究

在自行设计的反应装置中,以石英砂和质量分数3.5%的NaCl溶液模拟海底环境,选取南海北部高含N2和高含CO2天然气藏两组气样组成,分别在温度277.15K、初始压强6.37 MPa和温度275.15K、初始压强4.30MPa条件下进行了混合气置换CH4水合物实验,模拟高含非烃组成天然气渗漏对CH4水合物矿藏的影响。结果表明,CO2量变化最大,在置换CH4水合物过程中起主导作用,N2量变化较小。两种气样在不同实验条件下,反应时间140h时的置换效率分别达到8.64%和20.71%。基于实验结果,简单分析了多孔介质体系CO2置换甲烷水合物中CH4的机理。

Experimental Studies on the Replacement of CH4 Hydrates with Non-Hydrocarbon Gases

In order to simulate the effect of leakage of natural gases with high contents of CO2 and N2 on the methane hydrates reservoir overlying, the replacement experiments of CH4 hydrates by using two groups of gas mixtures were observed with a self-designed device at 277. 15 K, initial pressure 6.37 MPa and at 275. 15 K, initial pressure 4. 30 MPa respectively. The quartz sand and 3.5% NaC1 aqueous solution were mixed to simulate seafloor and two groups of gas mixtures, one has high contents of N2 and another has high contents of CO2, were chosen from northern South China Sea. Experimental data show that the variation of C02 is the most and the variation of N2 is much less. It indicate that CO2 plays a leading role. The replacement efficiency of two groups of gas mixtures at different experimental conditions are 8. 64% and 20.71% at 140 h of experiment. Based on the experimental results, a simple replacement mechanism of CH2 hydrate dissociated with CO2 in porous medium system was proposed.