Study Of Interactions Among Thermal-resistance And Salt-tolerance Heterogeneous Combination Flooding System

Heterogeneous combination flooding system composed of dispersed particle gel(DPG)and tetradecyl hydroxyl sulfo betaine(THSB)has been reported widely as a cost-effective EOR method due to highly beneficial synergistic effect.However,the interactions among heterogeneous combination flooding system have not been clarified,which will influence the application of heterogeneous combination flooding system in the oil fields.In this paper,interfacial phenomenon,interactions and distribution characteristics in the porous media of combination flooding system have been studied.The effects of various factors on interfacial tension and interfacial dilational rheology for heterogeneous combination flooding system have been measured.Aggregation state of heterogeneous combination flooding system was observed through laser scanning confocal microscope.Results showed that compared with surfactant system the interfacial tension of combination flooding system were relatively lower and temperature,pH and NaCl contents of solutions have almost no the effects on interfacial tension of combination flooding system.Increase of DPG particles concentration and aging time weakened interfacial dilational modulus while increase of THSB surfactant concentration made the interfacial dilational modulus increased.Cohesion force between DPG particles and mica sheet and shear force among combination flooding system were measured.The results showed that there was repulsion force between combination flooding system and mica sheet with different wettability.As THSB surfactant concentration,NaCl contents and aging time increased,the shear stress of combination flooding system reduced,which indicated that large numbers of particle aggregations were formed in the combination flooding system.The distribution state of combination flooding system in porous media was analyzed by measuring static adsorption,dynamic adsorption and chromatographic separation.Besides,the distribute state of combination flooding system was observed by means of visual simulation experiments and computed tomography(CT).Static adsorption showed that the surfactant adsorption capacity declined with the increasing DPG concentration,thereby decreasing the surfactant adsorption losses and increase of surfactant concentration promoted the adsorption of DPG particles by hydrophobic interactions,which would improve plugging capacity of DPG particles.Dynamic adsorption experiments showed that DPG particles can divert THSB surfactant into lower permeability zones and enhance the sweep volume of THSB surfactants.Due to the different interactions between combination flooding system and cores,heterogeneous combination flooding system has the chromatographic separation phenomenon in the porous media.Visual simulation experiments and CT experiments revealed the oil recovery mechanism of combination flooding system.