Development And Performance Evaluation Of A New Barium Sulfate Scale Inhibitor

The scaling problem is a difficult problem in the production of oil field,especially the problem of sulfate scaling.If we do not pay attention to the scaling in the water injection process,it will bring serious harm to the future oil field production.At present,the chemical scale inhibition method is used to restrain the formation of scale can be divided into organic phosphorus series and polymer series.But the scale inhibitor containing phosphorus discharged into the environment will pollute the water quality.With humans’ emphasis on the environment,the development of low phosphorus and non-phosphorus scale inhibitor has gradually become the hot spot in the development of green scale inhibitor.In this paper,we have synthesized a non-phosphorus scale inhibitor which used itaconic acid,acrylic acid,methyl acrylate and 2-acrylamido-2-methylpropane sulfonic acid as raw materials,ammonium persulfate as polymerization initiator.We developed a new scale inhibitor for barium sulfate scale inhibitior named GYDT,the non-phosphorus scale inhibitor are determined as follows:the mass ratio of initiator and total monomer is 8%,the reaction time 3h,the reaction temperature 80℃,n(itaconic acid):n(acrylic acid):n(methyl acrylate):n(2-acrylamido-2-methylpropane sulfonic acid)= 2:1:1:0.75,the inhibition rate up to 86.21%.The scale inhibitor GYDT is studied through the infrared spectrum.The results showed that the carboxylic acid group,ester group,aldehyde group and sulfonic acid group contained in GYDT can be complexed with metal ions to achieve the goal of scale inhibition.According to the industry standard,the scale inhibition performance of GYDT was evaluated:with the increase of temperature,the scale inhibition increased firstly and then decreased,the inhibition rate reached the maximum at the temperature of 85℃.The scale inhibition effect of GYDT was the best when the pH value was 7.5.With Ba2+ and SO42-ion concentration increasing,the inhibition rate decreased.When the concentration of Ba2+ was 800mg/L and the concentration of SO42-was 1000mg/L,the inhibition effect was the best.With the salinity increasing,the inhibition rate of GYDT on barium sulfate increased first and then decreased gradually.Based on the water analysis in Jiyuan oilfield of a certain oil pool and combined with the study of ScaleChem software on scaling prediction as well as the experimental research.It can be known that,the scale is the largest when the mixture ratio of injected water and D202-32 well is 5:5,and the maximum amount of barium sulfate is the mixture tatio of injected water and D202-32 well in 3:7.Then we chose five kinds of inhibitors for Jiyuan oilfield application evaluation,found that GYDT has good scale inhibition performance not only for barium but also for strontium carbonate,strontium sulfate,calcium carbonate to restrain,so GYDT can be applied to the field work in Jiyuan oilfield.