Abstract:

Shuangyang Qijia water source in Changchun City is close to the oil field, and the original division of one-level water source protection zone is not enough to reconcile the increasingly prominent contradiction between oilfield exploitation and water quality safety of water sources. In order to protect the groundwater drinking water source from the influence of oilfield development activities, a new division is needed to help the oilfield development layout in the area where the drinking water source is located. Firstly, the hydrogeological conditions in the study area were analyzed, the groundwater flow models and solute transport models of the water sources were established by using the MODFLOW and MT3DMS modules in the numerical software GMS (groundwater model system) on the basis of the original primary water source protection area. Then the secondary protected area division study was carried out in Shuangyang Qijia water source area in Changchun City to determine the degree and scope of pollution caused by the oilfield development activities. The simulation results show that after 1 000 d transportation in groundwater, the pollutants are 400-800 m away from the pollution source. On this basis, a total of 33.5 km2 of the secondary protected area is designated, and the oil wells originally planned in and around the designated area should be cancelled or properly relocated.

Key words: Qijia water source in Changchun, groundwater flow simulation, solute transport simulation, division protection area, groundwater model system