Study On Bioremediation Technology Of Abandoned Well Station Soil In Jiangsu Oilfield

With the development of oil exploration and development technology and the gradual enhancement of people's awareness of environmental protection,the problem of soil oil pollution has gradually attracted attention.At present,the problem of soil oil pollution is widespread in China's major oil areas.According to the national laws and regulations,the domestic oil and gas fields must repair the oil contaminated soil,but the domestic research in this area is relatively less,and the remediation and treatment are more Based on this background and the fact that Jiangsu Oilfield is located in the eastern region where land resources are scarce,we don't know the status quo of soil oil in this area.In order to find out the impact of Jiangsu Oilfield's exploration and development on Soil and the status of soil oil,this paper selects abandoned oil production wells in Jiangsu Oilfield for sampling and testing,and studies the rock in soil The content and distribution of oil and hydrocarbon and its relationship with soil pH value,total salt content,heavy metal content,organic carbon content,nitrogen and phosphorus nutrient elements;in order to implement the main responsibility of the industry in soil remediation,this paper further carried out the research on bioremediation of oil contaminated soil,based on the study of waste well site soil in Jiangsu Oilfield,and selected indigenous bacteria that can degrade oil in the source soil In order to optimize the construction of a more efficient mixed microbial agent,pot experiments were carried out to study the external environmental conditions such as the suitable environmental temperature,soil total salt content,microbial agent dosage and nutrient ratio of local crops combined with mixed microbial agents for soil petroleum hydrocarbon degradation.Finally,the actual effect of the experimental research results was investigated by field experiments in Abandoned well stations,The results are as follows(1)The content of petroleum hydrocarbon in the soil of Abandoned well stations in Jiangsu Oilfield varies from high to low.The more 30%of the well head soil contains more than 3000mg/kg petroleum hydrocarbon.Among the four wells with serious oil pollution,the petroleum hydrocarbon in the soil of the whole well site is mainly composed of C10-C40,which is unevenly distributed.The concentration of petroleum hydrocarbon within 5m is higher than that outside 10m.The petroleum hydrocarbon pollution causes the increase of soil pH and total salt content However,the C/N and C/P ratios increased significantly,and there was no risk of heavy metals exceeding the standard.(2)The indigenous microbial strains with good remediation effect on soil petroleum hydrocarbon were enriched and separated from Abandoned well station soil and self-produced crude oil in Jiangsu Oilfield.They were all in high activity at 26?-28?,and the effect was better when pH value was between 7-8.The mixed microbial community experiment showed that there were mutual inhibition and superposition between the bacteria on the surface,and the optimized mixed microbial community was used in the culture medium test The results showed that the oil removal efficiency reached 55.5%in 7 days.(3)Environmental factors have an important impact on the growth of microorganisms and crops.The results showed that 0.3%soil total salt content was suitable for the combination system of mixed microbial agent and crops;the remediation effect of carbon:nitrogen:phosphorus was better under the conditions of 240:20:1 and 240:10:1;under the suitable seasonal temperature,the indoor remediation effect of soybean and 150ml/kg mixed microbial agent,rice and rape and 450ml/kg mixed microbial agent was good,and the highest degradation rate of petroleum hydrocarbon reached 71.1%in 42 days.(4)In situ remediation experiment of soil in Abandoned well station of Jiangsu Oilfield,the degradation rate of petroleum hydrocarbon in the soil after ploughing was higher,and the effect of combined remediation of microorganism and crop was better than that of single action.The pH value of soil was reduced by 6.47%after 42 days.The maximum number of petroleum hydrocarbon degrading bacteria in the soil reached 3.15×106cfu/g,which realized 52.42%of petroleum hydrocarbon degradation and 78.95%of C10-C40 components.At the end of one season soybean planting,61.49%of petroleum hydrocarbon and 85.53%of c10-c40 components were degraded.