含水合物沉积物电阻率演化规律实验研究进展

PROGRESS IN EXPERIMENTAL RESEARCH ON RESISTIVITY EVOLUTION OF HYDRATE BEARING SEDIMENTS

电阻率对沉积物组成和微观结构具有极高敏感性,是反映水合物生成分解过程物性演化的重要参数。然而由于影响因素复杂,人们对电阻率随CH4水合物生成分解的演化规律仍不清楚。对含CH4水合物沉积物的电阻率实验研究进展进行了梳理,分析了电阻率的主要影响因素,总结了纯水、盐水、非饱和水等不同体系中水合物生成分解过程电阻率演化规律。研究认为,在纯水沉积物中,电阻率随着水合物的生成不断增大;在盐水沉积物中,成核阶段的排盐效应以及生长阶段的重结晶或Ostwald熟化现象都会导致沉积物电阻率的降低;对非饱和水沉积物,气体和水在重力、毛细管力作用下、孔隙溶液离子在渗透和扩散作用下,都对沉积物电阻率造成影响。基于上述分析,提出了水合物生成过程模型,探讨了电学特性实验研究未来发展方向,对水合物电学研究具有一定的参考意义。

Electrical resistivity is extremely sensitive to the composition and microstructure of hydrate-bearing sediments,and is often applied as a key parameter reflecting the evolution of physical properties during the formation and decomposition of hydrates.However,due to the complexity of influencing factors,the variation of resistivity with the formation and decomposition of CH4 hydrate is still unclear.Based on the research progress of resistivity experiment of hydrate-bearing sediments,the evolution of resistivity in the hydrate forming process in different systems,such as pure water,saline water and unsaturated water,is studied in this paper.The results show that in the sediments saturated by pure water,the hydrate develops gradually from contact mode to cementation mode;in the systems filled by saturated brine,hydrate occurs in a suspension mode and Ostwald maturation occurs;in the sediments with unsaturated water,hydrate occurrence changes from suspension mode to cementation mode.Based on the above analysis,a model of hydrate formation process is proposed by the authors,and the future development trend of experimental research on electrical characteristics is discussed.It is confident that the results have certain reference significance for hydrate electrical research.