Study On Remaining Oil Fractions After Polymer Gel Profile Control

China's dependence on foreign oil and gas will continue to rise,and there is a potential danger to energy security.On the one hand,actively developing the exploration and development of unconventional oil and gas resources can make up for the shortage of oil and gas resource supply;on the other hand,deep potential tapping of old oilfields is carried out to improve crude oil recovery and ensure energy supply.At present,most of the old oil fields in my country have entered the high water cut period,and the heterogeneity of the reservoir greatly restricts the development effect of the oil field.Existing profile control agents often only act as plugs in the oil layer near the water injection well.Water will quickly circulate and enter the high permeability zone again,resulting in limited depth profile control effects.Therefore,an effective and efficient profile control system for plugging was found,and the core displacement experiment method was used to quantify the distribution law of remaining oil in the reservoir after profile control to optimize the optimal adjustment of the polymer gel system during polymer flooding.The timing of the cut and the amount of the profile control agent are not important.In this paper,the static gelation strength of polymer gel systems with different polymer molecular weights,polymer concentrations,crosslinker concentrations,and stabilizer concentrations is first determined to determine the influence of gelation strength of polymer gel systems.The plugging experiment determined the best formula:1500mg/L polymer+0.3%Cr3+crosslinking agent+0.03%stabilizer A polymer gel system.Scanning electron microscopy was used to characterize the microstructure of the polymer gel,which proved the spatial network structure after gelation of the polymer gel system,and clarified its microscopic gelation mechanism and its deep profile control mechanism.The resistivity method is used to quantitatively describe the remaining oil distribution in the heterogeneous model.By simulating the water-flooding,polymer flooding and gel profile control experiments of the positive rhythm thick oil layer,the distribution rule of the remaining oil before and after profile control is clarified and the best is optimized Timing of profile adjustment.The theoretical method of Archie saturation and lithology is used to calibrate the saturation.The micro-electrode core model is used to measure the resistance value of different permeability cores under different oil saturation conditions,and the standard curve of rock-electric relationship is established to react.The oil saturation of a certain area in the core at a certain moment.By quantitatively describing the remaining oil saturation in the model under the conditions of different permeability gradients,different water injection time,profile adjustment timing and profile control agent dosage,the factors influencing the distribution of remaining oil in the reservoir after profile adjustment of the polymer gel system are clarified The best non-homogeneous conditions for profile control of polymer gels were developed,and the best profile adjustment timing and profile control agent dosage were optimized.The results of the study show that the greater the permeability difference,the worse the low-permeability layer in the waterflooding stage,but the better the profile control effect of the polymer gel system.The profile control is performed after 0.1PV before the polymer flooding,and the profile control effect is the best.The volume of the low permeability layer is the largest,and the oil washing effect is the best in the affected area;the injection volume of the polymer gel profile control agent is 0.196PV,and the profile control radius is 1/2 of the mainstream line of the high permeability layer.The highest degree of spread after sectioning.