INFLUENTIAL FACTORS IN NATURAL GAS MIGRATION AND ACCUMULATION

The factors influencing gas migration are studied by simulating natural gas migration in natural core,using long-core experimental installation.Natural gas migration is related to the physical characteristics of rock and the pressure of gas source.Gas migrates first into large pores of migration formations after overcoming the influence of capillary pressure.If migration formations have good physical properties and much larger pores,much more gas will be accumulated,otherwise it will migrate far away.It does not depend on time because the rate of gas movement is fast.When the pressure of gas resource is large enough to overcome capillary pressure,gas can migrate forward transiently.The differences between migrating upwards and downwards are great because of the buoyancy force.It is easy and high efficient to migrate upwards. The distance of gas migration upwards is three times of that of downwards in the same conditions.