Study On The Synergistic Mechanism Of Hydraulic Pulsation Enhanced Chemical Oil Recovery

Chemical tertiary oil recovery is the main means of improving oil recovery in conventional oilfields.With the development of water flooding,the dominant channel is gradually formed and solidified,the inefficient circulation of injected fluid is serious,and the utilization rate of chemical agents is low,which restricts the effect of enhancing oil recovery and increases the production cost.The hydraulic pulsation enhanced chemical oil recovery technology transforms continuous and stable injection into pulsation injection.With the help of the pressure disturbance of the displacement fluid in the reservoir,it effectively promotes the dispersion of chemical agents in the remaining oil,expands the microscopic and planar macroscopic spread of pores,improves the utilization rate of chemical agents,and greatly improves the recovery rate.At present,the composite technology has been successfully tested in the field,but the understanding of the composite synergistic mechanism and the analysis of the factors affecting the effect is not systematic enough,which has become the key to restricting the popularization and application of the technology.Based on this,this paper firstly used the glass bead sand filling model to carry out the flow experiment of hydraulic pulsation to promote the dispersion of oil and water agent and the emulsification of heavy oil,and to evaluate the sensitivity of pulsation parameters to the improvement of the dispersion efficiency of the oil and water agent system;and then used micro pulsation control device,carried out microscopic visualization experiments of pulsation water flooding and pulsation chemical flooding,analyzed the dynamic process of hydraulic pulsation enhanced oil displacement,and clarified the mechanical mechanism of pulsation on the dynamic deformation and migration of the oil-water interface;finally,by the hydraulic pulsation drive,the core flow experiments of pulsation water flooding and pulsation chemical flooding were carried out,and the influence of fluctuating parameters on the core waterflooding effect was evaluated.According to the NMR T2 spectrum curve and pseudo-color map,the dynamic pore sweep characteristics of pulsation to improve the recovery of water flooding and chemical flooding are clarified.Based on this,the main controlling factors and other influence sensitivity of the pulsation combined flooding effect are evaluated.The research results show that:(1)Hydraulic pulsation can effectively improve the dispersion efficiency of the oil-water agent system.When the pulsation frequency is low,the energy is low and the physical disturbance is insufficient,and the dispersion effect is poor.With the increase of frequency,the energy relay acts on the oil-water interface,which improves the dispersion efficiency,but the excessively high frequency decays faster.It can achieve local small oscillations,so the overall dispersion efficiency shows a trend of first getting better and then getting worse with the increase of the pulsation frequency;and the increase of the pulsation amplitude can enhance the shearing effect on the oil-water interface,so the dispersion effect is proportional to it.(2)From the microscopic scale of the pores,hydraulic pulsation can break the mechanical balance of the oil-water-solid interface and promote interface deformation.Under this action,the oil film is peeled off layer by layer,the columnar residual oil breaks through the finer pores,and the blind end oil and the contiguous residual oil are reduced.At the same time,pulsation injection makes the pressure distribution asymmetric and promotes macroscopic spread.In addition,a certain pore pressure level promotes the effect of pulsating water flooding,and continuous flow has little effect on the oil displacement effect.(3)From the perspective of core flow,hydraulic pulsation can trigger a drastic jump in pore pressure while increasing the overall pressure level,expanding the scope of water flooding,and enhancing the effectiveness of chemical agents,thereby greatly improving the water flooding effect;pulsating water flooding recovery The increase of the rate increases with the increase of the pulsation amplitude,and with the increase of the pulsation frequency,it shows a trend of first getting better and then getting worse;when the pulsation timing occurs after the water sees,the pulsation energy guides the energy through the core,and can stimulate the formation water to reach to microscopic pores;compared with stable chemical flooding,the recovery rate of pulsating combined chemical flooding has increased by more than 10%.The hydraulic pulsation enhanced chemical oil recovery technology can expand the pore sweep coefficient,strengthen the efficiency of chemical agents,and effectively improve the oil recovery.