Synthesis And Performance Study Of A New Type Of Scale And Corrosion Inhibitor

As the oil reservoir becomes difficult to produce,especially after primary and secondary methods have been exhausted,the CO2 flooding has been used in a wide variety of field applications,such as the exploration ofpetroleum,natural gas,coalbed methane and shale gas.It enhanced the oil production in the low permeability reservoir.However,the scale and corrosion problems emerge,which is caused by CO2 flooding.Usually,these will reduce the oil production and damage the use of oil field equipment as well.Moreover,it will develop serious accidents,which will impact on the economic benefits of market and oilfield development degree.This study focuses on the design of scale inhibitor molecule containing carboxylic acid polymer which has a corrosion inhibition effect In order to achieve the corresponding inhibition efficiency of the inhibitor,we mixed it with a corrosion inhibitor to develop a compound which is suitable for the CO2 flooding and able to solve the corrosion and inhibition problems caused by CO2 flooding.Through synthesizing a series of scale inhibitors and corrosion inhibitors and carrying out the related performance evaluation,we selected the proper scale inhibitor and corrosion inhibitor compound finally.(1)Three kinds of scale inhibitor were synthesized in the experiment Those are PIMA,PESA and p-MEA.Moreover,the structure of the synthesized products were evaluated by IR,1H NMR and TOF and a series of other evaluations were performed on the inhibitor.Finally,we screened the best inhibitor—?-MEA The optimal synthesis conditions were determined by orthogonal experiment method,the reaction temperature was 80?,the reaction time was 3 hours,the monomer ratio of ESA:?-CD-MAC:AMPS was 1:0.3:0.1,the amount of initiator was 2.0%(W).When the amount of PESA and ?-MEA is 30 mg/L and 16 mg/L,the barium sulfatse inhibition efficiency will reach 96.6%and 98.7%,respectively.When the dosage of PESA and?-MEA is 250 mg/L,the calcium carbonate scale inhibition efficiency will reach 93.5%and 96.3%,respectively.Through weight lo ss experiment,PESA and ?-MEA have some corrosion inhibition performance in tap water.(2)In this paper,three inhibitors SD-1,SD-AD and AD-AF(SD-AF1)containing N atoms and ?-bond were synthesized through Mannich reaction The structural characterization of the synthesized products were evaluated by IR and 1H NMR.Through the analysis of the corrosion results,we confirmed the corrosion inhibitor SD-AF1 as the research object The optimal synthesis condition was determined by orthogonal experiment.What's more,the reaction temperature was 85?,the ratio of reactant was n(SD-1):n(formaldehyde):n(acetone)=22:1 and the reaction time was 6 hours.Through the static weight loss test,we evaluated the performance of the corrosion inhibitor SD-AF1 in 3%NaCl solution saturated by CO2 when it is on N80 steel plate.When the dosage of the inhibitor reached 400 mg/L,the rate of the corrosion was 0.0446 mm/a,which was lower than the industry standard 0.076 mm/a.However,the corrosion rate was 90.4%,which reached the expected target in this paper.(3)Inhibitor(3-MEA was screened out to mix with corrosion inhibitor SD-AF1,and then we evaluated the property of the corrosion inhibitor ?-MEA/SD-AF1.The dosage of ?-MEA was 16 mg/L,while the dosage of SD-AF1 was 400 mg/L,which is the optimum dosage ratio.Based on evaluation standards(SY/T5673-1993)and(SY/T5273-2000),we set up a new evaluation method(ZH/T2017).Both the inhibition and corrosion performance were evaluated.The experimental results showed that inhibitor p-MEA and inhibitor SD-AF1 had a cooperative action and a good compatibility.We evaluated the time of inhibition,which was 16h.The inhibition rate reached 97.5%.When the inhibition time was 32h,the inhibition rate reached 90.5%.What's more,it had a strong ability to disperse iron oxide,which can be used in the application of inhibition and corrosion process after CO2 flooding.(4)The addition of ?-MEA significantly affected the growth of the scale crystal.Through the analysis performed by SEM and XRD,the morphology of scale BaSO4 changed significantly after adding inhibitor ?-MEA,turning to be in disorganized arrangement of irregular shape and breaking into small pieces.Morphology of CaCO3 crystal adding ?-MEA distorted,leading to a broken appearance,the surface exhibited amorphous the plane is not smooth.The growth state and some defects in the crystal surface can be very obvious differences from the calcite crystal structure.(5)Through the theoretical research of adsorption and electrochemical corrosion,inhibitor SD-AF1 is a mixed type inhibition cathode based inhibitor,SD-AF1 followed Langmuir isotherm adsorption on the surface of N80 steel sheet,forming a single molecule adsorption film and spontaneous chemical adsorption on the surface of N80 steel,which had good inhibition effect.Combined with AFM on the surface of N80 steel sheet was characterized,it was clear that SD-AF1 added N80 steel compared with blank different steel sheet surface was relatively smooth,showing that SD-AF1 formed an effective protective film on the surface of N80 steel.