Research For Process Optimization Of Treating Produced Water In Changqing Oilfield

The treatment of oilfield produced water is a reliable guarantee for effective water injection,and how to improve the water quality of the treated water is an important part in oilfield surface engineering.According to the current situation and existing problems of treating produced water process in Changqing Oilfield,the paper first makes a thorough investigation on the Daqing Oilfield and Changqing Oilfield.Several key technologies were summarized:sludge magnetic separation and dehydration technology,chlorine dioxide sterilization technology,ultraviolet and photoelectric sterilization technology,electrolytic salt sterilization technology,flocculant dry powder dosing technology and so on.Secondly,tracking tests of typical stations in Changqing Oilfield,such as Hu Yi joint station and AI Jia Wan joint station,are carried out to analyze the raw water quality,evaluate the operation effect,and optimize the screening of field agents.The test results shows the reason that the on-site water quality is not up to standard.And the rationalization proposal is given.Finally,according to the two actual situations of Changqing Oilfield,different processes are proposed and implemented respectively.The improved processesare proposed based on the existing foundation for the reconstructed stations;The new“drug-free gas floatation,biochemical treatment,continuous filtering of shallow sand,ultraviolet sterilization”processes and integrated mode of skid mounted integration are proposed for the new stations.The oil content in the produced water less than 8 mg/L and the suspended solids content is less than 3 mg/Lby the improved processes of the reconstructed stations;the average oil content in the produced water is about 5 mg/L and the averagesuspended solids content is about 5 mg/L by new process of new station,which are far below the relevant requirements of the recovery injection index of the produced water in Changqing Oilfield.In general,the operation cost of process modification is low in the existing station,the power cost is not increased,the pharmaceutical cost is only increased by 0.46 yuan/m~3,and the impact resistance load is strong.The new technology of the new station is novel,compact,open-air setting,small occupancy,short construction period and rapid commissioning,which is very suitable for the rolling edge expansion development mode of the oilfield.