The Research Of Simulation Study For Predict The Affection Of Shale Gas In Karst Area On Shallow Groundwater

If shale gas drilling is improper disposal in the process of mining,pollutants of the fracturing flowback liquid can contaminate groundwater system.In addition,guizhou province is one of the main distribution area of shale gas,the area has three shale gas drilling Wells,and this area is a typical karst landform and the karst fissures has developed in all groundwater aquifer,and there exist many mature underground river.For the above reasons,the simulation for predict the affection of Shale gas in karst area on shallow groundwater is difficult.This paper,taking a shale gas blocks in guizhou province as the research object.Through analyzing the characteristic of the karst groundwater system structure in the study area,this paper used the groundwater simulation software FEFLOW make a heterogeneous and anisotropic two-dimensional groundwater flow model which simulated the matrix and underground river in the karst groundwater system respectively,and the underground river using Discrete Feature simulation.On the basic of the flow model,the selected Cl-as the characteristics of the pollutants by means of chemical composition analysis of shale gas well flowback fluid.Established the characteristics of the pollutants migration model which coupling underground river in the study area,and simulated to predict the characteristics of the migration of pollutants in the karst groundwater system release.Predicted results show that: Under the condition of flowback fluid leakage,the area of influence of Cl-was mainly affected by groundwater convection dispersion in non-underground river area.After the Cl-from the pollution source which near the underground river enter the river,it quickly migrated to the underground river downstream,the scope of Cl-distribution along the underground river.The concentration of the Cl-in the underground river upstream is 1239.38mg/L;in the middle reaches is 952.461mg/L;and 862.151mg/L in the downstream is 862.151mg/L.Using the Discrete Feature can effectively couple the pore groundwater and the underground river,and it can simulate solute transport in underground river.