Research on flexible particle migration in porous media

Currently most of the oil oilfields in east China have been entering the late period of high water-cut development stage.Due to non-homogeneous formations and long-term water flooding,large pores come into being among oil-water wells.Great amount of water rotates deficiently along the pores and decreases the waterflood sweep efficiency.Field test shows that flexible particles(SR-3)can seal off the large pores effectively,but the migration mechanism needs further study.The paper mainly studies the migration of flexible particles in pores,and the capability of turning fluid direction generated by sealing pores with pore throat models.What’s more,it analyzes the effect of throat-particle diameter ratio,average length of throat,and injection rate of displacement on threshold-pressure and the shear damage of flexible particles.Results show that the flexible particles can go through little porous throat by deformation and generate continued fluctuate resistance in large pores,which helps to realize deep fluid diversion and enhance waterflood sweep efficiency.There exists the optimal ratio with throat-particle diameter to certain pores,which enables SR-3 to migrate stably in the formation.The migration of flexible particles to deep formations can greatly improve sweep efficiency and enhance oil recovery.And the elastic deformation of SR-3 is favorable for its migration to deep formations.