Experimental Study On Sediment Deformation During Natural Gas Hydrate Dissociation By Depressurization

Natural gas hydrate is a new type of energy with huge reserves and clean and pollution-free after combustion.It is an important way to solve China's energy problems in the future.However,most of the natural gas hydrates are stored 300 to 500 m below the seabed,and drilling requires deep into the reservoir for mining.During the process of natural gas hydrate mining,the deformation of sediments will cause the instability of drilling and seriously affect the safety of production.This paper design the decomposition of natural gas hydrate formation test process,deformation measurement device is analyzed by means of simulation test study of decentralized and stratified distribution of gas hydrate in buck the deformation characteristics of the sediment in the process of mining,for distributed mining process:(1)the distribution of natural gas hydrate step-down sediment was positively proportional function relation between strain and gas production;(2)the higher the NGH saturation is,the larger the sediment deformation will be;(3)the higher the porosity,the greater the deformation of sediments;(4)the deformation of sediments with larger particle size is larger;The relationship between the shape variable of gas hydrate and the number of layers was studied.