Synthesis And Demulsification Performance Of Polyether Ester Demulsifiers With Adjustable Molecular Weights

The high content of colloid or asphaltene in tight oil makes demulsification of produced liquid difficult,which is not favorable for later processing.This paper reference colloid structure characteristics,design synthesis of a series of oil soluble polyacrylic polyether ester demulsifiers,by changing the raw materials of molecular weight and degree of polymerization realize molecular weight control,infrared spectrum analysis was carried out on the synthetic product（FT IR）,nuclear magnetic resonance analysis(¹³C MAS NMR)and gel permeation chromatograph（GPC）,and other basic structural characterization,And the interface properties and thermogravimetric analysis（TG-DTG）analysis,and the demulsification of the produced tight oil liquid was studied.The results are as follows:（1）A series of polyether acrylate demulsifiers were synthesized by esterification and polymerization of polyether acrylate based on six different molecular weight linear polyethers and acrylic acid.The optimal esterification parameters were as follows:n _AA:n _L4=2.5:1,esterification time=8 h,esterification temperature=115℃,the optimal esterification parameters were L4,the esterification rate was 93.05%,and the molecular weight of the corresponding intermediate was 3714 g/mol.The optimized polymerization process parameters were polymerization temperature 85℃,polymerization time 4 h,at this time the molecular weight of the synthesized product4PEL4-2.5 was 4877 g/mol,1.4 times the molecular weight of the esterified intermediate,with good thermal stability at≤320℃.When 4PEL4-2.5 is 200 mg/L,the oil-water interfacial tension decreases from 28 mN/m to 5 mN/m.Its turbidity point is 10℃,HLB value is 5 and RSN value is 9.9.The contact Angle with water is 126.05°,and the contact Angle with oil is 1.16.According to the viscosity temperature curve,the demulsification temperature is 80℃and the demulsification time is 120 min,and the dehydration rate of produced tight oil liquid can reach 90.6%,which is 22.7%higher than that of 2816-1 demulsifier under the same demulsification condition.（2）A series of binary polyether ester demulsifiers were designed and synthesized using binary mixed polyethers of 4 octylphenolpolyethers of different molecular weights and linear polyether L4 as raw materials.When octylphenol polyether OP2 and propylene glycol block polyether L4 were mixed in a ratio of 1:9 as the polyether base and acrylic acid were esterification reaction,polymerization for 2 h,The molecular weight of synthetic demulsifier 2PE90L4-OP2 was 4397 g/mol,which was 1.1 times that of the esterified intermediate.The surface tension of its aqueous solution is 34.89mN/m.The turbidity point of binary polyether ester demulsifier was 16.6℃,the HLB value was 5.65,and the hydrophilicity was between the raw material and monodemulsifier.2PE90L4-OP2 reduced the oil/water interfacial tension to 1.8 mN/m,proving that the introduction of aromatic groups can effectively reduce the oil/water interfacial activity.The demulsification performance evaluation of tight oil produced liquid shows that the demulsification rate of tight oil produced liquid can reach 94.34%when the concentration of demulsifier is 200 mg/L,the demulsification temperature is80℃and the demulsification time is 120 min,which is 4%higher than the demulsification rate of tight oil produced liquid under the same conditions.