The influences of most factors on chemical characteristics of oilfield water change with the increase of burial depth

leading to the vertical zonation of oilfield water.According to the changes of groundwater salinity and Cl

-

concentration

five typical hydrochemical profile units could be divided from the shallow to the deep part

including meteoric water infiltration fresh zone (zone A);near surface evaporative concentration zone (zone B);fresh water from mudstone compaction (C

1

) and concentration zone by mudstone compaction and water-seepage (C

2

);clay mineral dehydration fresh zone (zone D); and deep concentration zone from seepage (zone E).