Simulation experimental result shows that the rate of natural gas migration decreases with the increase of compaction extent in carbonate or clay rocks. But in quartz sandstone

compaction extent has less effect on migration rate

high rate of migration which is 700 times as it in clay rocks was obtained even if in burial depth of 5000m (equal to 1300kg/cm

2

). The experimental result also indicates that

during migration of natural gas in carbonate or clay rocks

mineral matrices have different retaining abilities for gaseous hydrocarbons with different molecular weight. That is

C

1

and C

2

have the highest migration rate

and the ratio of C

1

/ΣC

1

-C

5

is not only related to the type of organic matter

but also to the migration distance of natural gas. Long distance migration may make it into dry gas.