Underground waters were involved in the entire proeesses of betroleum generation

migration

concentration and deterioration

An important approach for recognizing regularities of oil and gas distribution

therefore

is to study the evolution and motion of underground waters in oil- and gas-bearing basins. As for the case of Taizhou

Jiangsu proyince

hydrological phases and subphases are divided according to paleotectonic and sedimentary settigns. It is suggested that the form ation and preservation of oil and gas are related to hydrological subphases of deposition waters

while remigration

evolution and deterioration ofoil and gas to hydrological subphases of percolation waters. Based on paleogeo-logic characteristics and paleohydrodynamics

promising zones for oil and gas migration and concentration

i.e. the fault-step zones

and complicated hydrological patterns of deposition or/and percolation waters are described. Paleonydrological environments and tectonic traps which may produce negative influence to reservoirs are also discussed in terms of indensity index of water interechange

hydrochemistry

physical and chemical properties of petroleum and content end distribution of superficial minerals. Finally

a principle for evaluation of oil potentiality is given from the hydrological point of view.