Study On Steam Flooding Capacity And Displacement Characteristics Of Ultra-heavy Oil

China is rich in ultra-heavy oil reserves,but it is the most difficult to exploit.After years of development,production continues to decline,so it is urgent to change the development mode.At present,it is generally believed that ultra-heavy oil is not suitable for steam flooding,but some domestic field tests have achieved certain results,so it is of great significance to study the flow capacity limit and seepage law of ultra-heavy oil and the characteristics of steam flooding for its upproduction and stable production.In this paper,the flow boundary and displacement characteristics of ultra-heavy oil steam flooding are obtained on the basis of laboratory physical simulation experiment.Firstly,abnormal temperature points and critical temperature points of ultra-heavy oil were calculated by viscosity-rheological test,and the relationship between pseudo threshold pressure gradient and flow capacity was established combining with singlephase flow test of core.Then,core displacement experiment is used to describe the characteristics of oil-water two-phase seepage under different influencing factors.Finally,the flooding characteristics and produced liquid properties of ultra-heavy oil flooding under different influencing factors are analyzed by means of four-component and rheological tests.The results show that the abnormal temperature and critical temperature of super heavy oil belong to non-Newtonian fluid,and increase with the increase of colloid and asphaltene content.The pseudo start-up pressure gradient and fluidity of super heavy oil in porous media show a power function relationship,and decrease with the increase of temperature and permeability.The characteristics of two-phase flow of super heavy oil show that reducing viscosity,increasing temperature and increasing permeability are beneficial to improving oil phase seepage capacity and oil displacement efficiency.Reasonable increases in water flooding temperature and steam flow rate can increase asphaltene recovery,enhance distillation of light components,and form stable emulsions,thus greatly enhancing recovery.