海域天然气水合物稳定带厚度与其影响因素的半定量研究

海底沉积物中蕴含着大量的天然气水合物资源。水合物稳定带(HSZ)反映了海底天然气水合物的成矿作用和分布规律，稳定带厚度的影响因素决定了天然气水合物的蕴藏量。水合物稳定带的影响因素有很多种，但每种因素对其的影响程度不同。为探讨水合物稳定带厚度的分布规律，从分析海底天然气水合物相平衡影响因素入手，着重研究了影响稳定带厚度的水合物气体组分、地温梯度、海水深度、海底温度及孔隙水盐度等重要参数，并使用CSM Gem程序对这些影响因素进行模拟计算；然后利用模拟计算所得到的结果数据进行曲线拟合，直至得到较为可信的相平衡曲线；最后根据此相平衡曲线，结合相应条件下的地温梯度曲线方程求得稳定带厚度。通过对预设各条件值与相应得到的稳定带厚度值进行回归分析，得出稳定带厚度与各个影响因素的关系以及这些因素对稳定带厚度的影响程度。

Semi quantitative Research on the Relationship between Thickness of Marine Gas Hydrate Stability Zone and Its Influencing Factors

There are a large number of natural gas hydrate resources in marine sediments. The hydrate stability zone (HSZ) is an important factor to reflect gas hydrates mineralization and distribution, and the thickness of HSZ is a decisive factor for the resource of gas hydrates, thus the study of HSZ and its influencing factors is of guiding significance to the mineralization rule, distribution pattern and resource assessment of gas hydrates. The previous studies show that there are a lot of factors which can affect the HSZ, but their influencing degrees are different. In this paper, the phase equilibrium of natural gas hydrate was firstly analyzed, and then the important factors affecting HSZs thickness were emphatically discussed, ie. gas component, geothermal gradient, seawater depth, temperature in seafloor and salinity of pore water. With program CSM Gem, the influencing degree of these factors were simulated and calculated. Moreover, these calculated data were used to do curve fitting for a more accurate curve of phase equilibrium. According to this accurate curve, combined with the geothermal gradient the thickness of HSZ was obtained. With the regression analysis method, the relationship among the HSZs thickness and these influencing factors are semi quantitatively analyzed in detail.