| Heavy oil is a kind of important fossil energy.Under the background of the late stage of conventional crude oil development,it is very important to develop heavy oil.Steam flooding is a common method for heavy oil recovery,but steam channeling and other problems make the recovery rate of this method low,and the residual oil content in the bock after steam flooding is high.Therefore,it is necessary to find a method to improve steam flooding recovery.The foam produced by foaming agent has a plugging effect on high permeable layer,which can effectively improve the steam channeling problem during steam flooding.Sulfo betaine surfactant is a kind of foaming agent with certain temperature resistance and can be combined with steam flooding.Therefore,in this paper,2octyl-1-dodecanol sulfonyl group,with a complex structure of 2octyl-1-dodecanol as raw material,was synthesized through a series of reactions such as etherification and so on.The betaine surfactant was used to analyze the experimental data of steam foam displacement,and the displacement effect was tested to verify the feasibility of the mining method.Firstly,2octyl-1-dodecanol betaine surfactants were synthesized,and the surface tension and foam properties of five different concentration surfactant solution(1×10-3mol/L,1.5×10-3mol/L,2×10-3mol/L,2.5×10-3mol/L and3×10-3mol/L)were determined at room temperature.When the concentration of solution was 2×10-3mol/L the surface tension of solution was 31.9mN/m,which was the best value at room temperature.The properties of surfactant solution was stable at 120?after aging.When the solution salinity was6000mg/L,the foam property was stable,and the solution had good oil resistance.After that,one dimensional sand filling pipe steam foam flooding was carried out and the heavy oil obtained from liaohe oilfield was used in this experiment.Five different steam injection rates?1ml/min,2ml/min,4ml/min,6ml/min and 8ml/min?were compared when the experimental temperature was 120?and the salinity of simulated formation water was6000mg/L.When the injection rate was 4ml/min,the final oil production was7.1ml,the recovery rate increased by 29.6%,and the extraction efficiency was the best,so the experimental steam injection rate was determined to be4ml/min.Finally,three dimensional reservoir simulation device steam foam flooding experiment was carried out.The temperature was 120?,the salinity of water was6000mg/L and rate of steam injection was 4ml/min.Through comparison of oil saturation distribution map and temperature distribution map,it was found that the displacement surface of steam foam flooding was wider and more uniform,indicating that steam foam flooding effectively changed the steam channeling problem,and the experiment finally produced oil 1.61L and the recovery was 32.2%higher than that of steam flooding.The purpose of improving steam flooding recovery was achieved. |
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