Research On Dispersed Particle Gel Strengthened ASP Flooding System And Their Interaction Mechanism

In oilfield production,water flooding is globally one of the most commonly used processes.When the natural reservoir energy is depleted,water injection can effectively provide additional energy to maintain the reservoir’s formation pressure.However,after long-term water flooding treatments,the reservoirs’ permeability significantly increases,which provokes the reservoirs’ heterogeneity and decreases the necessity for water flooding.Thus,the changes in reservoir homogeneity and water-oil flow ratio reduce the swept volume of injected water.Consequently,oil recovery becomes more challenging to conduct,the changes in reservoir heterogeneity and water-oil flow ratio have become urgent problems for enhanced oil recovery.Therefore,to improve the enhanced oil recovery conditions,the displacement efficiency and sweep efficiency of the displacement agents need to be improved.So far,the chemical ASP combination flooding system is a practical method for enhanced oil recovery.However,in porous media,the reservoir temperature and salinity,the sheer deterioration,and the dilution affected the viscosity and viscoelasticity of the alkali-surfactant-polymer combination flooding system.In order to solve this technical problem,particles are added to improve the stability of the polymer system or ASP system.According to these technical difficulties,the dispersed particle gel can plug the high permeability zones through aggregation in pores and throats and can also effectively improve the profile control through direct plugging or bridging across pore throats in the formation.The added dispersed particle gel in the ASP combination flooding system will have a synergistic viscosity increase effect due to the dispersed particle gel viscosity ability.On the whole,the interaction reaction will appear in the combination flooding system.The dispersed particles will adsorb on the interface together with the surfactant molecules,and the aggregate between particles will enhance the adsorption film strength of the system.In the flooding experiments,the DASP combination flooding system will have a better mobility control capacity in the combination flooding stage and the subsequent water flooding stage due to the increase of the displacement efficiency and sweep efficiency of the displacement agent in the system.In the DASP combination flooding system,the dispersed particle gel could intersperse in the threedimensional network structure,which will increase the stability of the system in solution and porous media by effectively improving the profile control ability of the system.Through improving the synergistic effect of the swept volume capacity and high displacement efficiency,the DASP combination flooding system’s oil recovery capacity will significantly be enhanced.The DASP combination flooding system may be an alternative for enhanced oil recovery.In this research work,the dispersed particle gel strengthened ASP combination flooding system,and their interaction mechanism was proposed for the enhanced oil recovery process.For acknowledging the system’s screening criteria,the reservoir suitability and construction mechanism of the DASP as a novel combination flooding system were studied;furthermore,the application performance evaluation on the flooding capacity of the DASP as a novel combination flooding system for enhanced oil recovery.The interfacial dilational rheology phenomena reflected by the thickness of oil film analysis and the stability of oil-in-water emulsions were closely linked to the DASP combination flooding system’s adsorption capacity to describe the systems’ interaction mechanism and adsorption phenomena at the oil-water interface.In the DASP combination flooding system,the phase separation was formed due to the combined component’s effects,resulting in the differential migration between the systems,which led to different degrees of chromatographic separation phenomenon to affect the displacement mechanism.Therefore,the chromatography separation effects and the oil displacement mechanism through the hydrophilic glass-etched micromodel for the micro visual simulation experiment were investigated.After experiment investigation,the results indicated that the dispersed particle gel strengthened ASP combination flooding system has a comfortable network structure,higher viscosity,and viscoelasticity due to the system’s excellent characteristics.The DASP combination flooding system viscosity substantially increased through polymer concentration.The polymer was the principal viscosity agent;it immediately influences the mobility control capacity and,to some extent,the swept volume of the DASP combination flooding system.The added DPG particles adsorbed the surfactant molecule in the interface and interspersed in the polymer network structure by strengthening the DASP system structure,making the DASP system’s viscosity higher.For the study on the impact of the system’s external factors,the aging time and salinity affected the system’s interfacial tension reduction.After aged the system at60℃ for 60 days,the viscosity decreased,and the IFT increased.The three-dimensional structure of the DASP system was strengthened,and the aggregates formed by the association of DPG particles and surfactants cannot be degraded easily.Therefore,under reservoir conditions,the IFT reduction capacity resisted long-term aging,and the viscosity was still maintained.When the concentration of salinity increased in the DASP combination flooding system,this result caused hydrophobic association in the polymer structure.The polymer was the response of the driving force in the system.Additionally,we can explain the decrease in viscosity by the three-dimensional network structure binding force weakens due to the surfactant being driven out of the aqueous phase because the salt concentration increased.Via hydrogen bonding,the polymer molecules adsorbed on the sand surface.The presence of DPG particles generated a difference between the ASP and DASP resistance factors.When the sandpack pore channel got smaller than that of the particles in the DASP combination flooding system at the injection stage,the particles directly blocked the pore.When the sand packs pore channel got more extensive than that of the particle size,the multiple particles linked each other in the high permeability pore to realize the micro-control,whereas the system’s viscosity increased by a synergetic effect.The increase in interface elasticity produces significantly positive effects on the combination flooding system stability.The results revealed that the DASP combination has a higher resistance factor and a good regulation effect on the sand-pack high permeability.In the subsequent water flooding,the ASP combination flooding system’s resistance factor decreased more than that of the DASP combination system due to the polymer’s dilution contact with water injected.However,in DASP combination chemical flooding with the subsequent water flooding,the pressure began to decline,meaning that the DASP flooding system’s regulating effect decreased.When the DASP combination flooding system moved in a porous core medium,the dimensionless breakthrough time of the DASP in the combination flooding system was different.The phase separation was formed in the system,resulting in the differential migration,which led different chromatographic separation phenomena to affect the displacement mechanism.As we can see in the micro visualization simulation experiment,the residual oil interacted with Alkali molecules and formed the in-situ surfactant,making the remaining oil emulsified;as well,the surfactant adsorbed by DPG particle make the crude oil emulsified and get enhanced.The investigation on the DASP combination flooding system experiments results indicated a favorable application of the system in an enhanced oil recovery process.