Molecule Design and Synthesis of Surfactants for Surfactant-Polymer Combination Flooding

Abstract: The characteristics of alkali-free surfactant-polym er combination flooding (SP flooding) and basic req uirement for surfactants were discussed. Molecule design theorie s of oil-displacement surfactants for combination f looding were introduced, including HLB value of surfactant, R-ra tio (ratio of interaction energy of surfactant and oil with surfactant and water in interface layer), Molecule Geometry Pa cking Parameter (MGPP) and Quantitative Structure-P roperty Relationship (QSPR). The development progress and d irection of synthesis of oil displacement surfactan t for surfactant-polymer flooding were commented. SP flooding can avoid side-effects encountered in a lkali-surfactant-polymer combination flooding (ASP flooding), such as scaling, corrosion and strong emulsificatio n resulted in lifting problem and liquid treatment problems. The operation cost of SP flooding is low and it can be applied in oilfield more easily than ASP flooding. Accordingly, SP flooding is a promising chemical EOR technique. As no synergism with alkali, SP system requires higher performance surfactant than ASP system. Design and synthesis of new surfactants with good properties have become b ottle-neck problem in the application of SP flooding. HLB value equal 6-8 can be used for primary designi n and screening of oil-displacement surfactants, w hich is very convenience. R-value, MGPP, QSPR methods can be use d in fine designing of oil-displacement surfactants . These methods consider more detail of molecule interactio n among surfactant, oil and water in interface laye r. The coincident ratio of MGPP methods for designing of oil-displace ment surfactants is the best and it is easy to calc ulate and understand. Based on Molecule design theories, the structure ch ara teristic of surfactants for alkali-free surfact ant-polymer combination flooding should mainly focus on branch c ains, double trails alkyl and/or aryl sulfonate s urfactants, zwitterion surfactants, gemini surfactants and so o n. Some of them have been synthesized which have go od IFT properties.