含水合物沉积物的渗透率实验研究

Experimental Study on Permeability of Hydrate Sediments

天然气水合物储层的渗透率是影响水合物开采时气、水运移的关键,也是水合物开采潜力评价、资源评价、开采工艺选择等需要了解的关键参数。目前,国内外学者对天然气水合物储层的渗透率迚行了一定的研究并有了初步认识。但是,对于围压、轴向压力、水合物饱和度、赋存模式等对水合物沉积物渗透率的影响机制和机理还不清楚。本文在自主设计的水合物储层三轴渗透率测试平台上,实验研究了粒径、围压、轴向压力、水合物饱和度等对沉积物渗透率的影响。结果表明,采用不同围压测得的水合物沉积物渗透率存在较大差异:多孔介质粒径的减小会降低沉积物渗透率;甲烷水合物沉积物渗透率随着饱和度升高呈指数型下降;轴向压力的升高会降低甲烷水合物沉积物渗透率,沉积物水合物饱和度越高,轴向压力对沉积物渗透率的影响越小;轴压加载条件下甲烷水合物沉积物相对渗透率随饱和度变化与Masuda沉积物渗透下降模型拟合良好。

The permeability of natural gas hydrate reservoirs is the key to the migration of gas and water during the exploitation of hydrate resources.It is also a key parameter that needs to be understood in the evaluation of hydrate exploitation potential,resource evaluation,and exploitation technology selection.At present,scholars all over the world have conducted studies on the permeability of gas hydrate reservoirs and have a preliminary understanding.However,the mechanism and mechanism of the influence of confining pressure,axial pressure,hydrate saturation,and occurrence mode on the permeability of hydrate sediments is still unclear.In this paper,on a self-designed triaxial permeability test platform for hydrate reservoirs,the effects of particle size,confining pressure,axial pressure,and hydrate saturation on sediment permeability were experimentally studied.The results showed that the permeability of hydrate sediments measured with different confining pressures was quite different:the permeability of sediments decreased with the decrease of particle size of porous media;the permeability of methane hydrate sediments increased exponentially with the saturation increase;the permeability of methane hydrate sediments decreased with the increase of axial pressure,the higher the saturation of sediment hydrate,the smaller the influence of axial pressure on sediment permeability;the variation of relative permeability of methane hydrate sediments with saturation under the condition of axial load was well-fitted with the Masuda sediment permeability decline model.