中文摘要：

天然气水合物在未来的能源、环境及海洋地质灾害等方面有着重要意义，是当前研究的热点。根据琼东南盆地的实际地质条件，结合琼东南盆地深水区的海水盐度和地温梯度等，在不同水深条件下计算不同组分气体所形成的水合物稳定带厚度，研究非烃类气体对水合物稳定带厚度的影响。结果表明，琼东南盆地的水合物稳定带厚度随着海水深度的增加而增加，混合气体中的CO2对水合物稳定带厚度的影响不仅与其含量有关，还受海水深度影响。当水深小于或等于1．3kin时，混合气体所形成的水合物稳定带厚度随CO2含量的增加先增大后减1h；当水深大于或等于1．55kin时，C02使水合物稳定带厚度减小，并随C02含量的增加影响越大。CH4—喇2混合气体中的N2使水合物稳定带厚度减小，混合气体中的N2每增加1％时，所形成的水合物稳定带厚度将减少4m。

英文摘要：

Natural gas hydrate is a hot spot of study at present, which may play a very important role in energy, environment and disasters. According to actual geological conditions in the Qiongdongnan Basin, the influence of nonhydrocarbon gas to the thickness of hydrate stability zone （HSZ） is numerically studied for component gases at various depths, combined with the salinity of ocean waters and geothermal gradient in the deep-water area within the basin. The results show that the thickness of HSZ in the Qiongdongnan Basin increases with water depth, and that COz in mixed gas of CH4＋ CO2 alters the hydrate stability. The effect of CO2 is not only related to CO2 content but also to water depth. The thickness of HSZ increases at a shallow depth and then falls as CO2 content increases for water depth less than or equal to 1.3 kin. When water depth is more than or equal to 1.55 kin, input of CO2 decreases the HSZ thickness, and the influence enhances as the CO2 content grows. The results also indicate that N2 in mixed gas of CH4＋N2 decreases the thickness of the HSZ. A 1% increase of N2 in the mixture can lead to 4m reduction in the thickness of the HSZ.