Oil and gas field wastewater treatment is a complex and critical process, because wastewater contains a variety of pollutants, which will cause serious damage to the environment if discharged directly without proper treatment.
As a company that produces water treatment chemicals such as Polyaluminum chloride(PAC) and Polyacrylamide(PAM), Yuxinhuan's products play a key role in oil and gas field wastewater treatment.
1. Extraction water: This is the largest source of oilfield wastewater, mainly from the water-containing crude oil extract entering the three-phase separator to dehydrate the crude oil for pre-separation.
2. Drilling wastewater: wastewater generated during drilling operations, containing drilling mud, cuttings and other impurities.
3. Well washing water: wastewater generated by regular cleaning of oilfield injection wells.
4. Other wastewater: including oilfield condensate wastewater, sewage treatment station filter tank backwash wastewater, acidification residual liquid wastewater, fracturing fluid wastewater, etc. .
Oil and gas field wastewater contains high concentrations of oil, suspended solids, dissolved organic matter and inorganic salts, as well as possible heavy metals, radioactive substances and other toxic and harmful substances.
• Physical treatment: Remove suspended matter and oil in wastewater by gravity separation, centrifugal separation and other methods.
• Chemical treatment: At this stage, Polyaluminum chloride(PAC) and Polyacrylamide(PAM) produced by Yuxinhuan are widely used in the coagulation and sedimentation process. PAC, as a coagulant, can neutralize the negative charge in the wastewater and aggregate the suspended matter and colloidal particles into larger flocs; while PAM, as a flocculant, can enhance the stability and sedimentation rate of the flocs, thereby more effectively removing suspended matter and colloidal substances in the wastewater.
• Biological treatment: Use microbial metabolism to degrade organic matter and nutrients such as nitrogen and phosphorus in wastewater.
• Advanced oxidation treatment: Use advanced oxidation technologies such as ozone and ultraviolet rays to destroy the structure of organic matter in wastewater.
Membrane separation technology: Use ultrafiltration, reverse osmosis and other membrane separation technologies to remove tiny oil droplets, suspended solids and dissolved organic matter in wastewater.
Xinjiang oilfield produces a large amount of wastewater during the mining process, mainly composed of electro-desalting drainage, crude oil storage tank interception drainage, circulating water drainage, alkylation drainage, desalting station acid-base neutralization water, etc. These wastewaters have the characteristics of high COD, high oil mass concentration, high salt mass concentration and high cyclohexane acid mass concentration, which are difficult to treat.
① The oilfield wastewater treatment system adopts a combined process of "pretreatment + oil-water separation + coagulation sedimentation + biochemical treatment + deep treatment + disinfection discharge". The specific process is as follows:
② Pretreatment: The salty wastewater first enters the oil separator, and some grease and suspended matter are removed by gravity separation. Subsequently, the wastewater enters the regulating tank, which has a floating circulating oil collector to achieve the first oil removal of the wastewater.
③ Oil-water separation: The water in the regulating tank is pumped to the oil-water separator, and the suspended matter and most of the floating oil are removed through further treatment.
④ Coagulation and sedimentation: The wastewater flows into the vortex concave flotation and dissolved air flotation device, and after adding Polyaluminum chloride(PAC) and Polyacrylamide(PAM), part of the emulsified oil, suspended solids, etc. are removed by chemical reaction. In this step, the suspended matter and colloidal substances in the wastewater form flocs and settle down.
⑤ Biochemical treatment: The flotation effluent enters the A/O biochemical pool, and under the action of aerobic, anaerobic and parthenogenetic microorganisms, carbonization, nitrification and denitrification reactions are completed to remove organic pollutants and ammonia nitrogen in the wastewater.
⑥ Deep treatment: The biochemical effluent enters the MBR membrane pool, and after the MBR membrane mud and water separation, it is upgraded to the ozone oxidation tower and activated carbon tower. In the ozone oxidation tower, the pollutants in the wastewater are further oxidized by ozone; subsequently, the pollutants are further removed by adsorption in the activated carbon tower.
⑦ Disinfection and discharge: The treated wastewater flows into the monitoring pool, disinfected with sodium hypochlorite to ensure the safety of water quality, and then discharged into the environmental water or reused.
Treatment effect
After the above treatment process, the oilfield wastewater has been effectively purified. The effluent quality meets the standards specified in the "Comprehensive Wastewater Discharge Standard GB31570-2015", and part of the wastewater is reused, reducing production costs and water consumption. This case fully demonstrates the feasibility and effectiveness of oilfield wastewater treatment.
