According to the study of Mr.Guan Shicong et al.

Mesozoic and Cenozoic continental oil-and gas

bearing basins in Eastern China can generally be divided into two types:trough basins and broad basins Here chemical properties of oilfield water in these basins are discussed. Oilfield water in broad basins show single clustering patterns

enriched ions provided by factor 1 of factor analysis

little changes in mineralization

similar chemical properties of different basins formed in the same geological ages

high migration rate of chlorine-bearing water

lower content of phenol

higher content of benzene

lower average content and small changes in concentration of trace elements such as Li

Rb

Cs

Cu

Mn

Ni

V

etc. Whereas things are quite the opposite in trough basins. It seems that their differences might result from attributes of these basins

sedimentary formations and later modification.