Study On Formation And Decomposition Characteristics For Diagenetic Natural Gas Hydrate

There is a contradiction between the limited resources on the earth and the growing energy consumption by people.At the same time,the increasing fossil fuel consumption bring enormous destruction to the environment of our earth,to develop effective and clean energy becomes an urgent task to solve this problem,the discovery of gas hydrates provides a new and an appropriate choice.With the characteristics of large reserves,high energy density and clean,natural gas hydrates are considered as one of the most development prospect energy in 21st century.As a result,it is significant to perform comprehensive and in-depth research for natural gas hydrate reservoirs.Large amount of natural gas hydrates deposite in the permafrost zone and off shore buried under oceanic,it is known that natural gas hydrates are often dispersed in muds and rock strata.Scholars divided natural gas hydrate into diagenetic deposits and non-diagenetic deposits depends on the their storage environments.A lot experimental and theory research on non-diagenetic natural gas hydrate were performed by researchers,but little for the diagenetic natural gas hydrate.CoMPared to the non-diagenetic natural gas hydrate,diagenetic natural gas hydrate were also widely found in deep layer below the sea floor,in the permafrost zone and at the top of some gas reservoirs etc.In this paper,based on the insufficiency study for the non-diagenetic natural gas hydrate,an experiment platform for simulating the formation and dissociation of diagenetic natural gas hydrate was built,systematic experiments for studying the characteristic of formation and decomposition for natural gas hydrates were performed.First,a new and efficient dynamic natural gas hydrate formation method in porous media was developed,and complied with a calculation method of gas hydrate saturation,the effective of which was furthered demonstrated.Then by using acoustic wave and electrical resistivity test methods,the influence of porosity and permeability of porous medium,water saturation,brine salinity,temperature,pressure on the natural gas hydrate formation and decomposition characteristics was systematically investigated,and the relevant analysis for the experiment results.The experimental results obtained here will enrich the basic data and provide theoretical and technical support for the accumulation analysis and development of diagenetic natural gas hydrate.