Abstract
Field tests of ASP chemical combination flooding show that chemical combination flooding can greatly increase oil recovery for high water cut oilfields in China. The major problem in ASP flooding technique is that in the strong alkali ASP system, scaling and emulsification bring problems in lifting and produced liquid treatment. In order to avoid the side effect caused by using strong alkali, the development tendency of chemical combination flooding changes from strong alkali ASP flooding to weak alkali ASP flooding and to alkali-free SP combination flooding. The key problem in the weak alkali ASP flooding/SP flooding technique is to develop the surfactant with high interfacial performance, good oil displacement efficiency and lower cost. In this paper, the petroleum sulfonate was synthesized by using Ketone-benzol deep-dewaxing oil fraction as feedstock which with high aromatic content, screening the oil fractions by control average molecular weight of feedstock. The High viscosity stocks were sulfonated using short column falling film reactor. The active content of the petroleum sulfonates synthesized are higher than 38% by direct sulfonating process, it did not require further purification, and thus the synthetic process was improved and the cost was decreased. IFT property of the petroleum sulfonates synthesized showed that ultralow interfacial tension (10−3mN/m) can be reached for Daqing oil/formation water (weak alkali ASP system) and for Jilin oil/formation water (alkali-free SP system). Laboratory core oil-displacement of ASP/SP combination flooding showed that the oil displacement efficiencies of ASP/SP flooding with these surfactants can reach 62-65%(OOIP) which was about 20% and 18% respectively higher than that of the conventional water flooding.
