Numerical Study On The Effect Of Liu Yang Bao Gas Field Development On Ground Water Environment

Liu Yang Bao gas field,which is located in the west of Erdos basin,the junction of the Inner Mongolia Autonomous Region,the Ningxia Hui Autonomous Region and Shaanxi Province,has the huge amount of resources and development potential.It is one of the most important natural gas exploration and development area of sinopec.this paper is based on "Liu Yang Bao gas field 650 million m3 productivity construction project groundwater environmental impact assessment " project.As an example,Liu Yang Bao gas field is introduced to study the effect of gas field development on groundwater environment.First,we collect and sort previous studies about the research area.To understand the geological and hydrogeological conditions of the study area comprehensively,the hydrogeological investigation was conducted in detail.To obtain hydrogeological parameters of the vadose zone and aquifers,the field hydrogeological test is carried on in the vicinity of potentially contaminated sites.Then the hydrogeological conditions in the study area was generalized to establish a hydrogeological conceptual model.Through field pumping test and leakage test,hydrogeological parameters of layers are obtained.The corresponding numerical model of the groundwater flow follows,which is established with GMS software and corrected by the measured water level.After correction,flow model can better reflect the actual flow situation of the simulated area.Then the flow numerical model is used to analyze the influence of gas field exploitation of groundwater on the groundwater level and flow field.Results show that the exploitation of groundwater in Liu Yang Bao gas field has no effect on the groundwater flow field basically.Finally,a solute transport model is established,which is used to predict the degree of pollution of methanol,petroleum,COD and other pollutants on Groundwater Environment in potentially contaminated and representative site under accident conditions.The prediction results show that oil maximum concentration is about 0.66mg/L,COD maximum concentration is 9.1mg/L,the maximum concentration of methanol is 2.6mg/L,the largest area of groundwater exceed the standard is about 7800m2 during the forecasting period when the gas gathering station occurs sewage leak under accident conditions.When methanol sewage treatment plant occurrs wastewater leakage,the maximum concentration of petroleum,COD,methanols is 0.13mg/L,2.89mg/L,2.6mg/L,the largest area of groundwater exceeding the standard is about 8000m2 during the forecasting period.In general,under accident conditions the scope of groundwater contamination is very limited,which will not have a great impact on the groundwater environment.As long as the environmental protection measures are adopted appropriately,the effect can not only be controled on a smaller scale,but can even be eliminated.