含甲烷水合物沉积层渗透率特性实验与理论研究

含水合物沉积层的饱和度与渗透率关系研究,是深水油气及海洋水合物资源勘探开发的基础性工作.利用两种平均粒径分别为0.110和0.210mm的玻璃砂模拟沉积层环境,通过体积测量法确定其孔隙度分别为0.364和0.368.测量甲烷水合物在沉积层中渗透率随饱和度的变化,并将得到的结果与平行毛细管模型、Kozeny颗粒模型以及Masuda模型进行了比较.结果表明：模拟的沉积层可以近似认为是等径球体颗粒堆积物,其渗透率与孔隙度基本符合修正的Kozeny-Carman公式关系;沉积层中甲烷水合物的存在使其渗透率急剧下降;与多个模型比较后发现水合物占据孔隙中心的平行毛细管模型与实验结果吻合得较好,说明实验中甲烷水合物主要是在沉积层的孔隙中生成而不是对玻璃砂颗粒形成包络;甲烷水合物饱和度低于25%的沉积层渗透率与饱和度的关系成指数递减关系.

Experimental and theoretical study of permeability character of sediments containing methane hydrates

Study of the relationship between permeability and hydrates saturation in sediments is the basic work for exploration and exploitation of deep water oil,gas and gas hydrates.Sediments were simulated using two kinds of glass beads with mean diameters of 0.110 mm and 0.210 mm.Porosity of them was determined to 0.364 and 0.368 separately by volume measuring method.Water permeability was measured as methane hydrate saturation changed in sediments.The experimental data were compared with those of parallel capillary model,Kozeny grain model and Masuda model.Experimental results show that the simulated sediments can be considered to be packs of constant diameter spheres and the relationship between permeability and porosity agrees with revised Kozeny-Carman equation.Formation of methane hydrates in sediments induces distinguished decline of permeability and the parallel capillary model with hydrate forms in pore center is well fitted with experimental data.Methane hydrates mainly form in pores of sediments,but don′t envelop the glass beads in the experiments.Permeability of sediments reduces exponentially with saturation of methane hydrates under a low saturation,less than 25%.