Study On Chemical Scale Inhibition System Of Weak Acid Produced Water In Chunliang Oilfield

Recently,scaling and corrosion of gathering pipelines in the field is serious,which has a serious impact on the cost reduction and efficiency of the oil field.Although the use of chemical scale inhibitors in the filed can solve scaling,improper addition of scale inhibitors can lead to serious corrosion of the pipeline.Therefore,it is necessary to explore the scaling and corrosion mechanism in the gathering pipeline of Chunliang Oilfield,and find a suitable chemical scale inhibition system for scaling and corrosion products and provide corresponding solutions.In this paper,based on a thorough investigation of the mechanisms of scaling and corrosion in domestic and international pipelines,the structure types and key influencing factors of scaling and corrosion are explored through automatic ion analysis and XRD diffraction analysis of water in the pipeline.The static scale inhibition method and the cesium ion titration method were used to explore the chemical scale inhibitor system suitable for the gathering pipeline of Chunliang Oilfield,and the suitability of different chemical scale inhibition systems was explored.The mechanism of action of chemical scale inhibitors on different scaling products was investigated by scanning electron microscopy.According to the pipeline corrosion mechanism and coupon weight loss method,the corrosion inhibitor adapted to Chunliang Oilfield was optimized.And for the co-existence of scaling and corrosion in Chunliang Oilfield,the chemical scale and corrosion inhibition system suitable for the site is optimized.The results show that gathering pipeline in Chunliang Oilfield is dominated by calcium chloride water and also contains sodium bicarbonate and sodium sulfate water.It has the characteristics of high salinity,rich in scale forming ions and contains dissolved oxygen,carbon dioxide and other factors which are easy to corrode the pipeline.Through the analysis of the scale mechanism,it is found that CaCO₃,CaSO₄,BaSO₄ in the pipeline.FeO?OH?and FeCO₃are produced by the corrosion of the dissolved oxygen and carbon dioxide in the water.Calcium carbonate chemical scale-inhibition system is ZGCA?PASP-HEDP?chemical scale-inhibiting system,which optimal dosage is 12mg/L,and the rate of scale inhibition is 98.5%.Calcium sulfate chemical scale-inhibition system is ZGSC?PASP-HDTMP?chemical scale-inhibition system,which optimal dosage is 10mg/L,and the rate of scale inhibition is 97.7%.Barium sulfate chemical scale-inhibition system is ZGBA?TH-607B?chemical scale-inhibition system,which optimal dosage is 30mg/L,and the rate of scale inhibition is 85.6%.In view of the serious scale corrosion of the 53^#pipeline,the optimal scale and corrosion inhibition system is 27 mg/L,which contain 55.6%Imidazoline quaternary ammonium salt corrosion inhibitor+22.2%HEDP+22.2%PASP.The rate of scale inhibition is 98.6%,and the corrosion inhibition rate is89.8%.Aiming at the problems of 47^#pipeline,the scale and corrosion inhibition system is30mg/L,which contain 66.7%Imidazoline quaternary ammonium salt corrosion inhibitor+25%HDTMP+8.3%PASP.The rate of scale inhibition is 99.2%,and the corrosion inhibition rate is 84.6%.