Vertical zonation and planar division of oilfield groundwater chemistry fields in the Songliao basin, China

In the Songliao Basin, the formation and evolution of underground hydrodynamic fields controlled the formation and distribution of groundwater chemical fields, meanwhile, the chemical properties of groundwater reflected the evolutional outcome of hydrodynamic fields. There were many factors affecting the hydrochemical characteristics of groundwater in the forming process of groundwater chemical fields, and the affecting action of the factors also had characters of lengthways stages and planar selectivity, the former resulted in the vertical chemical zonation of groundwater, five units could be divided downwards on its profiles: freshening zone due to meteoric water leaching downwards (A), concentrating zone for evaporation near the ground surface (B), freshening zone due to mudstone compaction-released water (C(1)) - concentrating zone due to compaction and infiltration (C(2)), freshening zone for the clay mineral dehydration (D) and seeping - concentrating zone (E). The latter dominated the planar chemical d