ABSTRACT
Dongying Basin is a very important oil-bearing basin, the main oil-bearing stratum is Tertiary, especially Shane Group(Es). There are a large volume of hydrochernical data of groundwater of Shane Group. From Es2 to Es4, the average TDS of groundwater increases gradually (35,6 g/1 for Es2; 48.8 g/l for Es3; 52.4g/l for Es4), while the order of the highest TDS of ground water is Es2 (322.3 g/l), Es3 (303.3 g/l) and Es4 (223.4 g/l), being contrary to the paleo-salinity (8.2 g/l for Es2, 24.3 g/l for Es3, 32.0 g/l for Es4). It illustrates that vertical groundwater movement probably exists. The probability cumulative curve of TDS shows three different origins of the groundwater, low TDS water, intermediate TDS water and high TDS water. The three types water show regular variations in plane: the low TBS water distributes at the edge of the basin, the high TDS water distributes in the interior of the basin and around the faults, the intermediate TDS water exists in the middle of the Basin. Combining with the rNa/rCl coefficient, we can find that the low TDS water has high rNa/rCl coefficient (rNa/rCl>0.85), while the high TDS water has low rNa/rCl coefficient (rNa/rCl< 0.85). The history of deposit and evolution of the basin show that Dongying basin has undergone sedimentary hydrogeological action, infiltrated hydrogeological action and buried-confined hydrogeological action. Also combining with the structure of the basin, we can conclude that the low TDS water is from infiltrated precipitation, the high TDS water comes from the deeper aqueous stratum which plays a great important role in petroleum accumulation, while the mainly intermediate TDS water are sedimentary water. The groundwater of Dongying basin has three different genesis, i.e., infiltrated precipitation water, sedimentary water and the high TDS water from the deeper aqueous strata.
