Experimental Research Of Filtration Rules And Enhanced Oil Recovery Mechanisms Of Preformed Particle Gels

Most oilfields in our country have entered high water-cut stage,but a great deal of residual oil is still buried in the formation.Due to the long-period washing action of injected water,reservoir heterogeneity and interlayer contradiction are strengthened,which lead to the ineffective circulation of subsequent water.In addition,due to the limited plugging capacity,short effective stimulation period and poor effects,traditional small-diameter profile control techniques cannot reach the requirement of oilfields.It is very difficult for conventional crosslinking system to gel under formation conditions because of dilution,degradation and so on,which make crosslinking system gel hard at ground situations.Therefore,above conditions promote the research and application of preformed particle gels deep profile fluid diverting technique.Preformed particle gel(PPG)is a kind of absorbent resin gel comprised of crosslinked polymers,which possesses certain elasticity and intensity after water-absorbed swelling.It can migrate,deposit,plug,deform,break,and plug-remigrate to realize the function of dynamic profile control.This study firstly tests the water-absorbed swelling property of different kinds of PPG and the influence of temperature and salinity on water-absorbed swelling property through static experiments,and makes a selection.Then,models of selected preformed particle gels migrating in the porous media are studied by plane microscopic visualization experiment and its microscopic mechanisms are analyzed.Variable diameter capillary experiment and mechanics theoretical derivation are combined to study the critical condition and influential factors of PPG plugging-remigration.And shear property of preformed particle gels suspension is discussed by using single sandpack core model experiment.Based on the above results,single sandpack core model experiment is also conducted to study the plugging capacity of PPG and analyze the influence of volume concentration,injection rate and particle size.Then parallel double sandpacks core experiment is established to discuss the adaptive studies of enhance oil recovery techniques of heterogeneous reservoir high water-cut period,especially EOR techniques of PPG,which include the aspects of particle size,permeability ratio,oil viscosity,etc.