Study On Preparation And Performance Of Oilfield Compound Scale Inhibitor

With the large-scale exploitation of oil fields throughout the country,the oil fields have basically entered the high water cut stage of the third oil recovery,which contains a large amount of salt-forming ions,which breaks the balance of formation water,and uses a large amount of sewage re-injection treatment to produce a large amount in the rock formation.Calcium,magnesium and strontium,barium and other ions,corresponding to calcium and magnesium scaling and corrosion problems in pipelines.In severe cases,it will cause failures such as pipeline blockage,pump jamming,and increased water injection pressure,which will lead to a decline in water injection efficiency.The scaling problem of pipelines is becoming more and more serious,affecting normal and efficient oilfield production,and greatly shortening the oilfield exploitation period.The current research found that the wastewater produced by the oilfield industry mainly includes formation water in the oilfield and water injection for drilling.These waters contain large amounts of metal cations,which are extremely easy to generate inorganic salt scale,so scale inhibition has become a top priority.The main ingredients in oil field scaling are calcium carbonate,calcium sulfate or magnesium salt,especially calcium carbonate and calcium sulfate are the main problems that need to be solved in oil fields.In recent years,some oil field barium strontium sulfate scales have been dense due to their compact crystals and strong crystal forms.Strong adsorption force becomes a difficult problem to be solved for scale inhibition and dissolution and scale dissolution.Scale inhibitors are divided into three categories,namely inorganic phosphates,organic phosphate phosphonates and polymer scale inhibitors.Among them,the polymer scale inhibitor has significant effect due to its small dosage,and its dispersion and scale inhibition effect is much higher than other small molecule scale inhibitors.It has been widely valued and applied,and has become the main product of oil field scale inhibition.Low,small usage,significant effect and most applied.But the biggest problem faced by acrylic polymerization inhibitors is that one is prone to explosive polymerization during polymerization,causing excessive molecular weight and flocculation,loss of dispersion and chelation.The second is that when there is only carboxyl group,it is easy to form chelate with heavy metal ions,and it is not resistant to hard water and high temperature.to this end,(1)This thesis uses acrylic acid(AA),hydroxypropyl acrylate(HPA),2-acrylamide-2-methylpropanesulfonic acid(AMPS)as monomers,and ammonium persulfate as initiator to synthesize ternary Copolymer scale inhibitor AA/HPA/AMPS.Part of the copolymer is formed by free radical polymerization,so that the conversion rate reaches more than 97%.The organic base is added to form a salt to obtain a copolymer that is completely dispersed at the molecular level in water.The reaction temperature is 80?,the polymerization reaction time is 4h,the amount of solvent is 60%,the amount of initiator accounts for 8%of the monomer mass,and the molar ratio of the three monomers is n(AA):n(HPA):n(AMPS)at 2:1:1 achieves the best scale inhibition performance,and on this basis,it is formulated with small organic molecules to form a scale inhibition specifically for calcium and magnesium scaling.(2)A copolymer scale inhibitor specially used for barium and strontium strong scale in oil field was synthesized by free radical polymerization.The effects of different reaction temperature and time,pH value,monomer molar ratio,and amount of initiator on the scale inhibition rate were studied by single factor method.The optimal reaction conditions were explored to achieve the highest scale inhibition rate.The specific change law of scale inhibition rate varies with different factors.Strong barium and strontium scales require a variety of different scale inhibitors to produce good results.Therefore,this thesis experimented with several different organic phosphate scale inhibitors.Through orthogonal experiments,the optimal ratio of compound scale inhibitors was determined as:A3B3C2D1,ie AA/HPA/AMPS terpolymer,hydroxyethylidene diphosphate(HEDP),aminotrimethylene fork phosphate(ATMPA),Citric acid has the best scale inhibition ratio when the mass ratio is 3:3:2:1,comparing the scale inhibition ratio of polymer scale inhibitors and compound scale inhibitors.The conductance method was used to verify the research on barium sulfate scale,and the mechanism of the scale inhibitor on barium sulfate was discussed.Compared with the effect of different solvents,the results show that the effect is the best in propylene glycol methyl ether solvent,and it also plays a good dispersing role in the compound type scale inhibitor,making the scale inhibition effect more significant.By comparing the blank test group and the experimental group with compound scale inhibitors through SEM,it can be clearly observed that the addition of compound scale inhibitors significantly reduces the formation of scales and also significantly changes the morphology and structure of scales.Scale sorting,the experiment proves that the compound scale inhibitor has remarkable scale inhibition effect.