含水合物细粒土的渗透特性

Permeability Fine-Grained Soils with Natural Gas Hydrate

含水合物储层的渗透率是影响开采水合物效率的重要物理参数。为了研究水合物赋存对赋存沉积物渗透性的影响规律,参照南海神狐海域水合物赋存区的沉积物的颗粒级配,配制了试验土体,并合成了含四氢呋喃水合物细粒土,并且基于稳态法测试了含不同水合物饱和度沉积物试样的渗透率。试验结果表明,该试验含水合物细粒土的渗透率介于11.41mD和61.63mD之间;随着水合物饱和度增加,含水合物细粒土的相对渗透率明显下降,主要是由于水合物的形成填充了沉积物孔隙,减小了孔隙率,此外,水合物还有可能阻塞流体渗流关键通道,从而减小了渗流率;采用现有渗流模型对试验结果进行了对比,发现与Masuda模型(N=3)最为近似。

The permeability of porous material is an important physical parameter that affects the exploitation of natural gas hydrate.In order to study the effect of natural gas hydrate on the permeability of the hydrate deposition,this paper presents the laboratory tests of fine-grained soil samples containing natural gas hydrate.The gradation of the fine-grained soils contained tetrahydrofuran hydrate was similar to the grain size distribution of soils in in Shenhu area of the South China Sea.Then,the permeability of fine-grained soil samples with different hydrate saturations was tested based on the steady state method.The test results show that the permeability of fine-grained soil containing hydrate in this test is between 11.41mD and 61.63mD.As the hydrate saturation increases,the relative permeability of the hydrate containing fine-grained soil decreases significantly,mainly due to the hydrate formation that fills the pores of the sediment and reduces the porosity.In addition,hydrates may also block the porous fluid seepage,thereby reducing the permeability.The test results were compared using the existing permeability model,and it was found that the result was close to the Masuda Model(N=3).