Study On The Improvement Of Oily Wastewater Treatment Process At Wenmi Oil Production Plant In Turpan Hami Oilfield

Wenmi oil production plant in Turpan Hami oilfield has entered into the middle and later period of the mining,and water injection development has been commonly used.At the same time,oil additives are also widely used in order to improve the oil recovery which has resulted in increasing oilfield produced liquid water content,more complicated composition,and more difficult sewage treatments.This paper analyses and evaluates the oily wastewater physicochemical and biochemical treatment systems firstly with a variety of experiments and analysis in Wenmi oil production plant,and finds out the problems existing in the oily wastewater physicochemical and biochemical treatment systems and the reasons of unable reinjection.After that,the corresponding transformations on the biochemical treatment systems are adopted on the basis of optimization in water disposal reagents formula and dosing formulation of physicochemical treatment systems.Finally,we put forward dosing management improvements and water quality control countermeasures to the physicochemical treatment systems,and make evaluations to the transformed biochemical treatment systems,and also study on the oily water compatibility after physicochemical and biochemical treatments.The study results show:?1?The treatment process “precipitation deoiling-water quality modificationflocculating setting-two levels filtrating” has been used in oily wastewater physicochemical treatment system in Wenmi oil production plant.Problems exist in sewage treatments:?1?the treated sewage unable to reach the injection standard;?2?the rising pH value and serious scaling after water quality modification;?3?considerable amounts of sludge;?4?SRB value out of limits resulting in severe pipeline corrosions and poor water quality.?2?The treatment process “precipitation deoiling-secondary aerobic biochemical pool-flocculating setting-filtrating” has been used in oily wastewater biochemical treatment system in Wenmi oil production plant.Problems exist in sewage treatments:?1?a high content of dissolved oxygen in treated sewage causing dissolve oxygen corrosions easily;?2?the bacteria content out of limits;?3?hydrogen sulphide levels out of limits,and the aeration device bringing hydrogen sulphide to the air.?3?After some screenings to water disposal reagents adopting in oily wastewater physicochemical treatment system in Wenmi oil production plant,the best processing agent has been drawn: compound alkali+ 200mg/L poly aluminium chloride?PAC?+10mg/L polyacrylamide?PAM?+150mg/L fungicide?KF510?+100mg/L corrosion inhibitor?KYHS3#?+120mg/L scale inhibitor?FZ-325?.And recommended dosing process is: the buffer tank before adding the corrosion inhibitor,scale inhibitor,oxidation bactericide;Reaction tank before adding the compound alkali,coagulant;Note the pump again before adding the corrosion inhibitor,scale inhibitor,the oxidation fungicide.?4?The hydrogen sulphide can be pumped out to centralized treat after installing an ultraviolet sterilization device behind the filtrator in the biochemical treatment system in Wenmi oil production plant,which can deal with the bacteria content and hydrogen sulphide levels out of limits effectively.?5?Fe²⁺ and S^2-in oily wastewater after physicochemical and biochemical treatment system will give a FeS precipitate which causes suspended solids content out of limits.Therefore,mixed reinjection is forbidden.