| The production water reinjection in Puguang Gas Field is facing severe situation.The reinjection capacity of available reinjection wells is reduced rapidly,and the location for new reinjection wells is difficult to find and the construction cost is high.On the other hand,the water production is increasing over the years.Ineffective reinjection increases the pressure of environmental protection,resulting in waste of resources.If the surplus produced water can be reused as supplementary water after satisfying the water quality standard of circulating cooling water,not only the zero discharge of produced water can be realized,but also the water intake from the Hou River can be reduced,and thus the utility cost can be reduced,which has multiple benefits such as water saving,emission reduction and environmental protection.After extensively investigating accessible water treatment technologies and engineering cases,this thesis puts forward the advanced treatment process for the produced water in Puguang gas field according to the characteristics of the produced water,the quality of the produced water,as well as the requirements of reinjection and reuse.The comparative analysis,comprehensive evaluation,experimental test and on-site pilot test were carried out.The main work of this thesis is as follows:(1)This paper investigates the treatment plan of the produced water in oil and gas fields at home and abroad,the treatment process,the reference to the well-run gas field production water project case,the planning of the Puguang gas field produced water treatment mode,and the research on the advanced treatment process of the Puguang gas field.(2)Experimental tests and optimization design were carried out for major process steps such as removing hard,organic matter,high pressure reverse osmosis and evaporation in the advanced treatment process.These processes include Fenton oxidation,ozone catalytic oxidation,activated carbon adsorption,resin filtration,membrane concentration,and membrane distillation.The effectiveness of the treatment process was verified,and the better treatment plan and process parameters were determined,which laid the foundation for on-site implementation.(3)According to the characteristics and treatment requirements of the water produced in the Puguang gas field,three advanced treatment routes were proposed.Through the comprehensive analysis and comparison of technical analysis and operating cost,the advanced treatment route of pretreatment plus membrane concentration plus gas distillation(MVR)was determined.(4)In this paper,on-site pilot and engineering practice of advanced treatment of produced water in Puguang gas field was carried out,and on-site process optimization,equipment selection,on-site implementation and on-site testing were carried out,and the expected water treatment results were obtained.(5)The process can be reused after 80%of the produced water is treated in depth,and only 20%of the concentrated water is re-injected,which can reduce the cost of re-injection and water use,and effectively solve the problem of insufficient reclaiming capacity of the Puguang gas field,and has significant economic benefits.(6)Reducing the pollution of the surrounding water by the Puguang gas field is in line with the national and local governments’ requirements for comprehensive treatment of pollutants and stable discharge standards,and has achieved good social benefits.(7)The implementation of the research results of this thesis can greatly reduce the amount of reclaimed water in the Puguang gas field,and reduce the daily injection volume from 1250m3/d to 300m3/d in 2018～2027.This will effectively retain the reinjection capability of the existing reinjection wells in the Puguang gas field and ensure the sustainable development of the Puguang gas field. |
