EFFECT OF CHEMICAL FLOODING ON ENHANCING OIL RECOVERY AFTER WATER FLOODING IN HETEROGENEOUS RESERVOIR

The recovery enhancing effects of different flooding methods,such as polymer flooding,high molecule weight surfactant flooding,chemical water plugging were studied by physical simulation.The flow characteristics of different flooding systems and their function to enlarge the swept volume of oil reservoir were compared each other in the paper,by detecting the resisting force formed in porous media.Further more,flooding experiments of different chemical flooding systems in parallel sand-packed module were down to examine their efficiencies and abilities for enhancing oil recovery.Experiment results showed that,under same flooding rate,the resistance factor of polymer increase fast but can only reach a low level at last,while the resistance of high molecule weight surfactant and emulsion produced increase slowly but can reach a high level.Three flooding methods can all improve the development effect in a degree,but surfactant flooding is the best one.The reasons are that,the surfactant selected in the paper can result to emulsification with oil,and then induce high resisting force in porous media.The integrated effect can start-up the residual oil in high permeability layer,and at same time,turn the route of flooding fluid to low permeability layer.In this way,the recovery factor and swept efficiency can be enlarged greatly,and the development effect of heterogeneous reservoir can be improved correspondingly.Thus,using surfactant flooding after water flooding in heterogeneous reservoir has a distinct advantage for enhancing oil recovery.