有效应力升降过程中不同饱和度水合物沉积物渗透率实验研究

为了研究天然气水合物开采过程中水合物饱和度和有效应力变化对含水合物沉积层渗透率变化规律的影响,利用自主研制的水合物沉积物合成与三轴渗流实验一体化装置,进行了有效应力升降过程中不同饱和度水合物沉积物渗透性实验。结果表明:有效应力升降过程中,不同饱和度水合物沉积物的渗透率与有效应力均呈负指数规律变化,并表现出在低有效应力阶段渗透率变化的幅度大于高有效应力阶段;有效应力升降过程中,试样产生的不可恢复变形使渗透率不能完全恢复,造成渗透率永久损失;有效应力不变时,水合物沉积物的渗透率与水合物饱和度呈负指数规律变化,且曲线的斜率随饱和度增加由大变小;水合物的饱和度越大,最大渗透率损害率越大,渗透率恢复的程度越差。

Experimental Study of Permeability Variation of Hydrate Bearing Sediments with Different Saturations during Effective Stress Loading-Unloading Process

In order to study the influence of hydrate saturation and variation of effective stress during natural gas hydrate mining process on the permeability variation, permeability experiment of hydrate bearing sediment with different saturations during effective stress loading-unloading process was carried out, by using an self-developed integrated device of hydrate sediment synthesis and three-axial seepage experiment. Results show that during effective stress loading-unloading process, the permeability of hydrate bearing sediment with different saturations varies according to negative exponential regulation with the effective stress variation. The permeability variation amplitude at low effective stress stage is greater than that at high effective stress stage. During effective stress loading-unloading process, non-recoverable deformation of specimen causes the permeability can not be completely recovered, resulting in permanent loss of permeability. When the effective stress is constant, the permeability of hydrate bearing sediment varies with saturation according to negative exponential regulation, and the curve slope decreases with the increase of saturation. The greater the saturation degree of hydrate is, the greater the damage rate of maximum permeability, the worse the permeability recovery.