Study On The Surfactant Of Ultralow Interfacial Tension And Its Application In Daqing Oilfield

Synthesis technics conditions of surfactant with the ultra low interfacial tension were determined through synthesizing surfactant of soyabean oil acid alkanoamide SBA. The characteristic functional groups of raw materials and products were analyzed by infrared absorption spectroscopy. The interfacial tension characteristics of the surfactant of alkanoamide with different carbonchains were studied. The order of the interfacial tension can reach 10^-3mN/m when the concentration of SBA is between 0.16%and 1.8%, the lowest value of them can reach 6.1×10^-4mN/m. If SBA is mixed with myristate or palmitic acid alkanoamide, the concentration of surfactant to reach the ultra low interfacial tension will reduce and the velocity of the interfacial tension of the combined system will increase.Interfacial tension, absorption effect and displacement characteristics of the combined two-component mixture of polymer and SBA were discussed. The influence of polymer concentration, salinity and temperature on the interfacial tension of the combined two-component mixture were studied。the results indicated that polymer concentration and salinity had more influence on the interfacial tension, and the order of the interfacial tension of SBA system can reach 10-3mN/m when the salinity is between 1400 and 11000 mg/L. The findings indicated adsorbance of the two-component mixture is less than 1mg per gram sand by mensuring the absorption isotherm of the SBA two-component mixture onto Daqing oil sand.The displacement characteristics of the two-component mixture are related to the type of polymer. For the two-component mixture of generally-used polymer and the surfactant, the chemical flooding recovery efficiency can reach more than twenty percent when the concentration of polymer is 1350mg/L and that of SBA is 0.8%; and, for the two-component mixture of functional polymer and the surfactant, the maximal chemical flooding recovery efficiency can reach 30% over water flooding.The effect of indoor pressure-dropping of SBA system was discussed, and the injection pressure can drop 50 percent by using surfactant SBA. The findings of the field test indicated that the injection pressure can be droped down 1.5 MPa by using SBA surfactant,less than the fracture pressure so that the higher concentration polymer can be injected under lower pressure.Interfacial tension between the different concentration SBA surfactant system and the crude oil of the production well for huff and puff was discussed, the order of them can reach 10-3mN/m. Through emulsification test, the surfactant concentration used in field huff and puff was determined. The findings of indoor oil displacement test by the fluid of the huff and puff indicated that the recovery efficiency can increase 15.8 percent after water flooding when the concentration of surfactant is 2 %. For the field huff and puff test, the average oil production increased by 118 ton oil per well in three oil wells of the Oil Production Plant No.4, while the average oil production increased by 128.6 ton oil per well in five oil wells of the Oil Production Plant No.2.