Investigate On Optimization And Flooding Performance Of Nanoparticle Composite Foam Flooding System

With the development of society,the demand for oil by countries is increasing day by day.As an important EOR technology,foam flooding for the advantages such as the controllable fluidity,profile control and oil displacement,and wide application range,has become an important enhanced oil recovery technology in China and even in the world.Obviously,A good foaming and foam stabilizing performance is the key to improving the oil displacement efficiency of the foam flooding technology.Therefore,in this experiment,the AOS surfactant was used as a foaming agent and the silica nanoparticles were used as a stable foaming material.Whether silica nanoparticles can stabilize foam were investigated using a foam observation system.The influence of nanoparticles on the properties of N₂ foams was studied using a multi-functional core flooding device,the experiment mainly investigate the oil displacement performance of nanoparticle foam flooding and also analyzed the related flooding mechanism.The specific experimental results are as follows:?1?The AOS critical micelle concentration?CMC?was measured use a surface tension test setup,and the results is 0.03wt%.And based on the result,a cylinder experiment was conducted to carry out preliminary design and optimization of the nanoparticles composite foam system.The cylinder experiment shows that the foam system produced by adding nanoparticles into low AOS surfactant concentration has good foam properties,the foam life can be maintained for 8 hours while the pure AOS surfactant foam is last only for 4.5 hours.?2?The bulk foam experiment was performed used a foamscan setup,during the experiment,the AOS surfactant was used as foam agent,different type of silica nanoparticls were used as foam stabilizer.The results showed that:although the hydrophilic silica nanoparticles cannot generate any foam alone,but it can still play a certain role in stabilizing low AOS foam.Such as the solution of0.02wt%AOS+0.15wt%hydrophilic silica nanoparticles can stabilize foam for 14h while the pure 0.02wt%AOS surfactant was only 8h,however when it compared to high AOS concentration,such as 0.06wt%AOS which can stable foam for 22h,the results is not ideal.Then we used different concentrations of hydrophobic silica nanoparticles and AOS surfactant solution to perform the experiment,the results showed that hydrophobic silica nanoparticles can partially replace the surfactant.The foam stability was greatly improved by adding hydrophobic silica nanoparticles into the surfactant solution.And at high nanoparticle/surfactant concentration,such as 0.06 wt%AOS+0.10 wt%silica nanoparticles,the foam can reach a long-term stable.?3?For the coreflood experiment,the effect of hydrophobic silica nanoparticle concentration and the gas injection rate on foam strength was investigated.In the experiment,we observed the mobility reduction factor of the foam in the porous medium by cyclically increasing or decreasing the concentration of the hydrophobic silica nanoparticles?or the gas injection rate?.The results show that the mobility reduction factor increases with the increase of hydrophobic silica nanoparticles concentration and the gas injection rate,which indicates that the strength of the foam is stronger at high hydrophobic silica nanoparticle concentration or high gas injection speed.During the experiment,we keep the AOS surfactant concentration at0.05 wt%.The results of the coreflooding experiments further indicate that the hydrophobic silica nanoparticles can partially replace the AOS surfactant for foaming or stabilizing foam.