Contamination Characteristics and Mechanism of Groundwater Movement in an Oilfield in Northeast China

The ways in which pollutants enter the ground water were analyzed, based on the known distribution of contaminated ground water in two aquifers in an oilfield. The study shows that the anomalies of CODMn, Cl–, NO3−, and TDS resulting from petroleum pollutants may be used as the reference indices of petroleum contamination. By and large, two aquifers are either polluted seriously or at medium level. The concentration of petroleum pollutants in the lower aquifer is considerably higher than that in the upper aquifer. The ground water pollutions are classified into two categories, i.e., by infiltration and by penetration. The ground water polluted by infiltration is a relatively minor threat to the oilfield compared to the pollution by penetration through geosutures resulting from geological structural movements, which is the major cause of ground water pollution.