Study On Improving Viscosity And Oil Displacement Efficiency Of HPAM Solution

At present,the technology of polymer flooding to improve oil recovery has been widely used in domestic oilfield.HPAM due to its good increasing viscosity is widely used in each big oilfield flooding oil project.However,under the high concentration of divalent metal ions,HPAM aqueous solution will be degraded.And the carboxyl groups in molecules will be combined with the bivalent ions such as calcium,magnesium,forming flocculation,precipitation and occurred phase separation.At the same time,the dissolved oxygen in the polymer aqueous solution will also made the HPAM aqueous solution to occur oxidative degradation.These degradation caused HPAM aqueous solution viscosity reduced.Eventually lead to the oil displacement efficiency becoming worse obviously.This paper analysis and research the influence rule on the polymer concentration,temperature,pH,salinity,concentration of divalent ions,dissolved oxygen aim at the viscosity and stability of HPAM aqueous solution.Based on this rule to propose a new method by cooperate with polymer oil displacement agent and additives to enhance oil recovery.Based on the principle of complexation reaction by using complexing agent to remove high metal cationic in the HPAM aqueous solution,the viscosity of the HPAM aqueous solution;By adding antioxidants to reduce the degree of HPAM oxidative degradation,to enhance the stability of HPAM solution viscosity.Based on four kinds of complexing agent and three kinds of antioxidants to conduct optimization experiments.Found that adding oxalic acid as complexing agent can effectively improve the initial viscosity of HPAM aqueous solution by 33.2%;adding thiocarbamide as antioxidant,when the ageing time is 30 d HPAM aqueous solution's viscosity retention rate can reached to 65.5%.The result of the indoor oil displacement experiment shows: the simulated water after using complexing agent and antioxidant to dispose the HPAM aqueous solution's chemical flooding recovery efficiency can be increased by 3.2%,for high content oil field with high cationic to carry out polymer flooding technology is of great significance.