Research On Oil Displacement System Of Composite Surfactant Suitable For Low Permeability Oilfield

This paper mainly uses dodecyl hydroxysulfonate betaine with low interfacial tension as the main agent and complicates with nonylphenol polyoxyethylene ether ammonium sulfate,dodecyl hydroxysulfonate betaine,sodium dodecylbenzenesulfonate and OP-10 to obtain NSOPA composite surfactants.Based on the technical index of oil repellent,the performance of compound surfactant NSOPA oil repellent system was evaluated synthetically.Taking the technical requirements of surfactants for composite flooding as the evaluation standard,experimental studies have shown that the surface tension of 0.5% NSOPA composite surfactant is the lowest,and the surface tension decreases with the increase of the concentration of NSOPA composite surfactant.When the temperature is 60 ?,the interfacial tension decreases with the increase of the concentration of NSOPA composite surfactant.The interfacial tension of0.5% NSOPA composite surfactant is the lowest,but considering the economic conditions,0.4%NSOPA composite surface The interfacial tension of the active agent has also met the ultra-low interfacial tension level of 10-3.The salt resistance of NSOPA composite surfactants is better,among which the calcium salt resistance is the best.The interfacial tension of different concentrations of composite surfactant NSOPA saline solution increases with the increase of ion concentration,but after reaching a certain degree of salinity,The change gradually slows down,and the interfacial tension can still be kept low.NSOPA composite surfactant has better temperature resistance.0.4% NSOPA composite surfactant has the best emulsifying effect.With the increase of the concentration of NSOPA composite surfactant,the rate of water release decreases and the emulsifying ability increases accordingly.The composite surfactant NSOPA solution can change the wettability of the rock to weak hydrophilicity,which is conducive to the improvement of crude oil recovery and can effectively improve the recovery effect of low-permeability oil fields;the chemical flooding rate of NSOPA composite surfactant is the highest.When the injection volume reaches 0.5PV,the chemical oil displacement rate of the NSOPA composite surfactant can reach a maximum of 17.4%,effectively improving the oil recovery factor.