Preparation Of Surfactant For EOR And Study Of ASP Formulation

ASP (alkaline-surfactant-polymer) flooding is a novel method to enhance oil recovery in the development of oilfield, the key technology of it is to choose the proper surfactant. The sulfonate surfactant is widest used in the ASP flooding.In this study, oleum and sulfur trioxide were used as the sulfonate agent, heavy alkyl benzene and distillate oil were sulfonted under the different conditions. The effect of rate of reactants, reaction temperature, reaction time and different distillate oil on the properties of petroleum sulfonate were studied. The rate of reactants (acid:alkyl) is a important factor. Because the content of arene is very low in the distillate oil the content of surfactant is also low.A serious of separating, determining methods were established to analyse the content of alkyl benzene sulfonate. The volatile composition, sulfonate surfactant, unsulfonate oil and inorganic salt in the synthetic product were analyzed by the method of extraction. The mean molecular weight of the alkyl benzene sulfonate was determined by two-phase titration with a mixed indicator (Dimidium briomide disulphine blue) and the cationic surfactant was hyamine1622. The sulfonic group of the surfactant was characterized by the characteristic absorption peak of the IR spectrum, the molecular weight distribution of sulfonate by mass spectrum. The theory and process of determining mono-sulfonate and bi-sulfonate with HPLC were introduced in detail. By these methods we can analyze the composition of surfactant, on the other hand, we can provide necessary conditions to instruct the study and production of surfactant.The physical and chemical properties of synthesized surfactant must be evaluated to judge if this surfactant can meet the demand of ASP flooding and fit the water and oil of daqing oilfield. The results of IFT tests show that the IFTvalue between the oil and ASP solution can reach the order of 10-3mN/m, so the surfactant can meet the standard of ASP flooding. According to capillary number theory the residual oil saturation can be decreased when the capillary number is increased, while the decrease of the IFT between ASP system and oil is the effective way to increase the capillary number, so this paper focus on the study of the factors which can affect the IFT. The distribution factor of surfactant between ASP solution and oil is about 1 and the IFT can reach the ultra-low range. Both the concentration of alkaline and surfactant can affect the distribution and diffusion factor of surfactant, they can affect not only the dynamic IFT but also the equilibrium IFT, while the polymer can only affect on the diffusion factor of surfactant, so the polymer can only affect the dynamic IFT instead of the equilibrium IFT. When we studied the effect of the structure of surfactant on the IFT we found some interesting phenomenon: several kind of alkyl benzene sulfonate with different molecular weight were mixed, the IFT between ASP solution and oil can reach ultra-low range when the rates of the various sulfonate are proper. The higher is the mean molecular of surfactant the lower alkaline concentration of the ASP system is needed to reach the ultra-low IFT range, whereas, the lower is the mean molecular of the surfactant the lutra-lower range move to the higher alkaline concentration. There is a special molecular weight distribution in the surfactant consisted of the homologue of alkyl benzene sulfonate, at the special distribution the IFT between ASP solution and oil is lowest. Compared with the linearchain-alkyl-benzene-sulfonate the branch-alkyl-benzene-sulfonate has the better effect on reduction of the IFT. Not only the composition of the water phase can affect the IFT, the composition of the oil phase can also affect the IFT. In the four composition of crude oil (saturated hydrocarbon, aromatic hydrocarbon, resin, asphaltene), the resin plays the mainrole to reduce the IFT.The displacing system interacts not only with the reservoir fluid, at the same time, the interaction between the ASP system and reservoir rock can not be...