SEDIMENTATION-CONTROLLING FACTORS OF NATURAL GAS HYDRATION

Natural gas hydrate is an unconventional natural gas mineral,whose formation and distribution depend upon both certain temperature-pressure conditions and proper sedimentation conditions. By the end of 2002,totally 116 hydrate sites in the world had been discovered,but only 23 sites directly saw hydrate (of them,20 sites in sea and three on land ). Now the researches of hydrate sedimentation conditions are still at the very beginning,and the documents concerned are still lacking.The authors think that there are only four factors controlling sedimentation of hydrate,namely,lithologic characters,sedimentation rates,organic carbon contents,and sedimentary environments and sedimentary facies.