Study On Treatment Process Optimization And Sludge Reduction Of Produced Water In Jingbian Gas Field

Jingbian Gas Field purification plant adopts coagulation sedimentation method to treat the produced water.Field investigation shows that the existing treatment process cannot meet the effluent quality standards,and the large amount of sludge produced has a great impact on the purification plant.Therefore,it is urgent to optimize the chemical dosage of the existing process in the purification plant.At the same time,explore new produced water treatment technology,in order to improve the produced water treatment effect,to provide a reference for the field process upgrading;And reduce the amount of oily sludge on site.In this paper,a field investigation was conducted on the Jingbian gas field purification plant,and then the p H,∑Fe content,SS content and oil content of the produced water after treatment were taken as indicators.Single factor experiment and orthogonal experiment were used to optimize the dosage of the existing field process,and field tests were carried out.In order to optimize the treatment process of produced water in the field,ozone gas flotation method was put forward,its technological parameters were determined by single factor experiment,field pilot test was carried out,and economic evaluation was carried out.A centrifugal method was proposed to reduce oily sludge on site,and the technical parameters were determined.The main research conclusions are as follows:（1）The field investigation found that there were blockage problems in the field produced water treatment pipeline.Before treatment,the produced water was acidic,with high salinity and scale cation content and total iron content ranging from 102 to 425mg/L.After treatment,the water was alkaline,SS and oil content were not up to standard,and the concentration and dosage of chemicals used in the original process were unreasonable.The analysis selected 6%（m/V）of Na OH reagent,H₂O₂ stock solution（27.5%（m/V）of concentration）,0.1%（m/V）of PAM solution for follow-up experiments;（2）After treatment,the p H of produced water was mainly affected by the dosage of Na OH,and the∑Fe content was mainly affected by the dosage of Na OH and H₂O₂.The optimal dosage results of the field process were as follows:Na OH 600mg/L,H₂O₂ 0.6m L/L,PAM 4mg/L.The field application shows that the flocculant settling speed and treatment effect after optimization are obviously better than before optimization,the removal rate of∑Fe has little change,and the removal rates of SS content and oil content both increase by 6%～8%.（3）The optimal treatment conditions of ozone flotation experiment were as follows:the dosage of Na OH was 600mg/L,the ratio of air to water was 1:6,and the dosage of PAM was2.5mg/L;In the pilot experiment,the maximum removal rates of∑Fe,SS and oil content were94.1%,85.8%and 82.6%,respectively.The treatment cost decreased from 2.78 yuan/m² to 1.92yuan/m².（4）Sludge moisture content was 95.74%,oil content was 0.40%,sludge dewatering rate was 92.18%,dewatering capacity was 84.99kg/（m²·h）,and sludge volume reduction rate was68.8%.Centrifugal method was used for reduction test.The optimal treatment conditions in laboratory test were as follows:the rotation speed was 3000r/min,the centrifugation was 20min,and the sludge was reduced by 80%after treatment.The centrifugal dewatering device with horizontal spiral discharge and settling centrifuge as the core was selected in the field test.The sludge treatment capacity was about 7m³/h,the liquid content of the treated mud cake was 72%-78%,and the sludge reduction was reduced by about 81%.