Study Of Transferring And Transformation Of Pollutants In The Waste Fluids From Well Field And Its Influence On Groundwater System

Along with development of economy in China and exploration of oil and gas field,more and more artesian well has been drilled,which exhausts a large amount of waste liquids from the well field.Furthermore,the species and amount of the pollutants increase obviously year by year,which seriously influences on the surroundings gradually. At present,there is more potential in the exploration of oil and gas field in the northwest of China,which,to some extent,accelerates the deterioration of soil and water in this region. Therefore,much more attention should be paid to environmental protection in order to adapt to rapid paces of exploration and drilling of oil and gas field,to alleviate the influence of pollutants on environment,to pursue the harmonious development between energy exploration and environmental protection and to integrate the benefits of economy, environment and society,all of which have the theoretical significance and using value for the study of the transferring and transformation regulation of pollutants and its influence on the groundwater system..The objective to be researched in this study includes five parts,they are the slurry in the well field which has been being drilled from April in 2007,No.40-16 Well drilled in 2002,No.3816-4 Well drilled in 2003,No.40-16 Well in 2004,No.55-6 Well in 2005 and No.12-34 Well in 2006 respectively,all of which are in Su Ge Li Gas Field.First,it will analyze the transferring and transformation character of the constituents in the slurry and establish the relevant assessment system,based on which it will do the research on the influence of the pollution constituents in the waste fluids from the well field on the soil around.At the same time,it will also analyze the block of plastic protecting film laid on and around the bottom of the slurry pool and the disposal effect of pollution solidified.Finally,it will evaluate and analyze the influence of the waste fluids in the well field on the environmental quality of groundwater system,and the analyzed results are as follows:The slurry added in course of gas field exploration mainly includes COD,petrolic pollutants,carbolic acid and some kinds of heavy mental such as copper,lead,nickel, chromium,cadmium,arsenic,mercury,etc..And it has been found that all of these pollutants have been characterized by the following transferring regulation that transversely further these pollutants are away from center of pollution,the lower the density of each pollutants will be;longitudinally the deeper the pool is,the more all kinds of pollutants in the well will be,above which excludes the carbolic acid that is highly volatile and could not be monitored in the slurry pool in the passed five years.The further it is away from the slurry pool longitudinally or transversely,the lower the density of the pollutants such as the organics,petrolic substances,sulfide,heavy mental,etc.diffused in the soil outside the slurry pool will be.And the pollutants which seriously pollute the soil around the slurry pool include organics,petrolic pollutants and sulfide.The plastic protecting film laid in the slurry pool could effectively prevent the pollutants from diffusing to the edge of the pool.However,as the year passed,the block of the film would be worsened,and the perfect period of the film to prevent the pollutants could last 2 years.The water exhausted from the slurry pool could reach the emission standard by adopting disposal way of pharmaceuticals addition and deposition.For the reason that most of the poisonous pollutants will be transferred into the deposit matter,the disposal of the deposit matter will be the key process in the whole course of pollution deposal.The diffusing condition of the pollutants outside the slurry pool is characterized that the organic pollutants,such as COD,do not pollute the groundwater now,and its influence on the surrounding soil is in the scope of 10 meters from the edge of slurry pool;the maximum depth of pollution of petrolic pollutants is about 8.3 meters deep,and the diameter of its influence is about 20 meters from the edge of slurry pool,which also does not pollute the groundwater now.While it is possible that the sulfide has already polluted the groundwater,and the diameter of its influence may be in the scope of 20 to 30 meters from the edge of slurry pool,which requires the further exploration and study.