GC-MS

UV and TSF have been used to measure traces of hydrocarbons (

<

10

-6

)in shallow and surface layers in various areas

such as Lishu of Songliao

Ordos

western Sichuan

Tianchang of Northern Jiangsu and Yakela of Northern Tarim. Vertical micro-migrations of hydrocarbons from subsurface sources have thus been proved

which would result in halo-source relationship of dispersion haloes over the sources. There will be no exception even if the reservoirs are buried at a depth of over 5000m and there are tight seals. Presently

study of the basic principles of geochemical exploration is relatively weak. In view of this situation

we should begin with the observation of geochemical fields at depth

and determine the traces of micro-percolation of hydrocarbons in combination with fine seismic and geologic data

so as to verify different mechanism hypotheses. At the same time

we should also pay attention to dynamic observation of subsurface hydrocarbon micro-percolation

strengthen study of fabric geochemical field and genesis of geochemical anomalies

and speed up the simulation tests of relevant mechanisms.