Reaserch On The Environment Impact Assessment Model Of The Coal-Bed Gas Development

The storage of coal-bed gas is abundant in the south of Hancheng,Shannxi province.Development of coal-bed gas resources will rapidly increase according to the National Energy Development Plan in the period from 2011 to 2015.Coal-bed gas will as a new clean energy boarded the stage of history.Although the development of coal-bed gas is effectively alleviate the "energy shortage" and "environment" the double pressure of simultaneous selection,but its effect on groundwater environment is undeniable.According to the Technical guidelines for environmental impact assessment—Groundwater environment(HJ610-2011),construction projects must carry out environmental impact assessment of groundwater.Based on the analysis of regional geology and hydrogeololgy of the study area,in this dissertation,we identify the fields of study area,boundary types,initial groundwater flow field,and source and sink,etc.And also set up a hydrogeologic conceptual model.We use VB executable program?MAPGIS?Arc View and Access to handle model data.On the basis of hydrogeologic conceptual model,we constructed a numerical model of groundwater flow in the bedrock fracture and a prediction model of typical area by the equivalent porous medium method.The simulation results show that the flow field in the study area will change a little in the 20 years of the forecast period(2013-2032),and that seepage of reservoir in the field will not have a great impact on the area groundwater flow field in the study area.Through analyzing of coal-bed methane engineering,we summarizing the pollution sources and screening the predictive factors(F-?Fe?SO42-)in the study area.We also calculated the pollutant concentration in the construction period,the production period and retirement period.Based on groundwater flow model,we set up a solute transport model with the aid of the module of MT3D.The simulation results show that in the three kinds of pollutants the migration biggest distance is 64.55m and biggest range of influence is 786.03m2.The two values are all small.The contaminant transport distance and the range of influence also is small in others kinds of well-site.Coal-bed methane development project will not cause great impact on the surrounding environment.