| This article focuses on the complex oil-water relationship,mutual occurrence of oil-gas and water-layer,serious heterogeneity and other problems exist in the complex fault-block"double-high"reservoir,based on the favorable conditions of stable operation of the system and strong adaptability of ground injection process,the study of HPAM/petroleum sulfonate composite flooding was carried out.First,carrying out research on water treatment for chemical flooding and polymerization.The results of the experiment show that the presence of ferrous iron in freshly produced water is the main cause of polymer degradation.As the concentration of ferrous ions increases,the viscosity of the polymer solution decreases sharply.The content of ferrous ions extracted from water should be at least controlled within0.2mg L,and the viscosity loss of the polymer solution can be controlled within 10%.Bacteria and dissolved oxygen have a greater impact on the thermal stability of the system.After 60 days of divalent iron ion content in water,the viscosity retention rates of the samples before and after adding the bactericide were 31%and 77%,respectively.The viscosity retention rates of the samples before and after deoxygenation were 11%and 71%after 50 days.Finally,according to the experiment,adding 50mg/L of bactericide,5mg/L of iron ion treatment agent and 150mg/L of stabilizer to the system solution,It can effectively reduce the influence of on-site sewage on the viscosity of the polymer solution and the influence on the thermal stability of the system.Secondly,the binary system is optimized and evaluated.The results of the experiment show that the interfacial tension between the BHS-01A surfactant composite system and the target block heavy oil can reach the order of 10-3m N/m when the concentration is 0.3%,and it has good compatibility with the partially hydrolyzed polyacrylamide of the provided polymer.And the optimized concentration is:the surfactant concentration is 0.5%,and the polymer concentration is 1500mg/L.The viscosity of the system is 53.2m Pa·s,the interfacial tension with heavy oil can reach the order of 10-3m N/m,and it has good adsorption,thermal stability and shear resistance under the geological conditions of the target block.The influence of crude oil viscosity ratio?coefficient of variation and injection method on the enhanced oil recovery of the binary system was studied through indoor simulation flooding experiments.The experimental results of mobility control show that with the increase of viscosity ratio,average reservoir permeability and permeability variation coefficient,the contribution rate of oil displacing agent mobility control ability to oil recovery increases.The experimental results of the injection method show that the enhanced value of the recovery factor in the segmented slug injection method finally reaches 25.9%,and the maximum value of the recovery factor in the overall slug injection method is 21.6%.The comparison shows that the three-stage slug injection method has a better displacement effect.Finally,according to the selected injection parameters,the field injection test was carried out,and the overall situation showed that the water cut decreased and the output increased steadily. |
PDF Full Text Request