According to geologic model of unsteady groundwater flow in heterogeneous medium and adopting the finite difference solution

the direction and strength of oil gas migration can be quantified.Tarim Basin had three main oil gas generating phases including the early Hercynian

the late Hercynian and the Himalayan phases

Modeling result suggests that

in the early Hercynain

groundwater flew from the source depression to the around areas.Tazhong

Shaya Uplifts and the south and east of Shaya Uplift are favourable for oil gas migration.As the early Hercynian movement was very strong

fossil oil pools were exposed on surface and mainly denudated;in the later Hercynian

the oil gas migrated to Tazhong and Tabei Uplifts

accumulated in Tazhong;in the Himalayan stage

because of intense surface waterfall and draining

fissil oil pools were distoried;the fullness of the pools decreased

and pressure system was changed.