Synthesis and Application of Demulsifying Wax Inhibitor
Some production wells in Karamay Oilfield of Xinjiang have wax deposition.Adding paraffin inhibitors can effectively alleviate this problem,but at the same time,it leads to increased production and operation costs.In order to reduce the operation costs,a demulsifying paraffin inhibitor is developed to achieve one agent with multiple effects.The demulsifying wax inhibitor is synthesized by acylating PEI-1 000(polyethylene imine,Mw 1000)with fatty acid,followed by grafting PO/EO,and finally end-capping with fatty acid.The effects of fatty acid carbon chain length,PO dosage,EO dosage,acylated fatty acid dosage,and end-capping fatty acid dosage on the performance of the demulsifying wax inhibitor are investigated using the single-factor control method.The results show that the wax inhibition,viscosity reduction,and demulsification performance of the demulsifying wax inhibitor increased first and then decreased with the increase of each factor.The optimal formulation is determined as follows:PEI-1 000:stearic acid=1:6(molar ratio)for acylation,PEI-1 000:PO=1:99(mass ratio)for PO grafting,(PEI-1 000+PO):EO=3:1(mass ratio)for EO grafting,and PEI-1000:fatty acid=1:8(molar ratio)for end-capping.The indoor evaluation of the optimal formulation shows a demulsification rate of up to 90%,a wax inhibition rate of 50%,and a viscosity reduction rate of 40%.Field experiments demonstrated that the formulated demulsifying wax inhibitor effectively inhibited wax deposition,extended the well-cleaning cycle by more than 8 months,and improved the static demulsification rate of the produced fluid by 85%compared to the previous method.
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