Abstract: In the process of oil field development, the discharge of oily wastewater to the environment will contaminate the subsurface soil and ground water in aquifers. In order to simulate the wastewater contamination to the environment, a two-dimensional unsaturated water flow and contaminant transport model was established, which was coupled with the well-known ground water flow and contaminant transport model MODFLOW and MT3D. Since the lower boundary of the unsaturated model is coupled with the moveable water table, an iteration method is applied to solve this problem with a node property identification technique. Authors investigated the geological and hydrogeologic conditions of Songfangtun Oil Field of Daqing Petroleum Administration, the largest petroleum production base in China. A Field test of oil seepage through subsoil was carried out. Soils and oily wastewater were sampled to make laboratory experiments in determining their properties of adsorption and bio-degradation. The above model is applied to simulate the soil and ground water contamination caused by the discharge of oily wastewater to the environment. Results show that the discharge of oily wastewater will cause heavy contamination of the subsurface soils. Wastewater will finally enter the phreatic aquifer though the time period of flow from the ground surface to the water tables is related to the discharge rate and source concentration of oil contaminant. Since ground water flow in this plain area is very slow, and there are no water supply pumping station nearby, the contaminated area is not large. It will take 45 years before the contaminated water is drinkable again (concentration＜0.05 mg/L). The results of this study provided sound information for the design and construction of Songyi Integrated Wastewater Treatment Station.

Key words: oily wastewater, numerical simulation model, node property identification, contaminant transport

摘要： 建立了耦合入渗带与潜水层的地下水渗流和石油污染物迁移的数学模型，给出了模型的数值解。针对可变潜水面边界给出了节点变性和迭代求解方法。在认识大庆宋芳屯油田基本条件的基础上，运用实际地质、水文地质条件和上述模型，对宋一联合站含油污水外排环境的污染范围、程度和自净作用进行了模拟分析。含油污水外排不仅造成土壤的严重污染，而且由于土壤自净能力的降低，最终将使污水以原生浓度进入含水层。由于含水层处于饱水状态，生物降解能力和对污染物的吸附能力不如表层土壤，因此，污染物将在很长的时间内存在于含水层之中。本研究对含油污水外排所造成的土壤和地下水污染提供了定量评价方法。

关键词: 含油污水, 数值模拟, 节点变性, 污染物迁移