Study On The Adaptability Of Hyperbranched Polymers Prepared By Sewage In H Well Area Of Xinjiang Oilfield

After the implementation of water injection treatment in the H well of Xinjiang Oilfield,the exploitation has deteriorated,the proportion of production-absorption has gradually declined,the water ratio has increased,and the rate of annual absolute oil production has also gradually decreased.The specific reasons are as follows:Uneven distribution of formation pressure and flooded.Uneven utilization in small layers.The reservoir with strong heterogeneity and large range of penneability,making water fingering and inundation heavily.To solve these problems,it is proposed to use hyperbranched polymers to increase the oil recovery.In this paper,we have selected three polymers HBP-P1,HBP-P2,and HBP-P3 with different molecular weights and concentrations to study their properties.The results show that at 43?,the hyperbranched polymers which are prepared by oilfield sewage have good viscosity-increasing properties,temperature resistance,viscoelastic properties,and shear-thinning properties.Because of three-dimensional spherical shape,highly random multi-branched structure,and hydrophobic association,the hyperbranched polymers have larger molecular clew dimension than KYPAM-2500.The adaptability of hyperbranched polymers in Xinjiang H area is studied.Through experiments,we have counted the injection capacity of hyperbranched polymers solutions formulated with sewage at 43? and injection rate of 0.3mL/min.In this conclusion,when the injection concentration is 1500mg/L(slightly larger than CAC),the adaptive permeability of HBP-P1 is Kw?150mD.HBP-P2 is suitable for injecting in cores with Kw?290mD,and HBP-P3 is suitable for injecting in cores with Kw?500mD.When the permeability is lower than 80mD,a lower molecular weight or concentration polymer solution system is needs to obtained good injection performance.The static adsorption curves of hyperbranched polymers on quartz sand are in the "S" shape.The maximum adsorption retention is 152.37?g/g when HBP-P3 of 1500mg/L injected into 1000-8#,and the decreasing rate of penneability increase with the increase of adsorption retention.The smaller r/Rh is,the more pore volume could not be get into.In the results of polymer flooding experiments,HBP-P2 of 2500 mg/L injected into 1000-9#have the largest inaccessible pore volume of 0.299 PV.The retained polymer in the core have large viscoelastic effect,and the relaxation time varied with the molecular weight and concentrated of the polymer and core permeability.In addition,the critical viscoelastic velocity of HBP-P2 of 1500 mg/L is around 0.1 mL/min.The effects of injection speed,slug size,core permeability and polymer viscosity on the oil displacement effect are studied.The results show that hyperbranched polymer in sewage can improving oil recovery effectively,and when inject HBP-P2 with concentration of 1500 mg/L into the core with water permeability of about 300mD,the optimal injection rate is 0.3mL/min,and the optimal injection slug size is 0.32PV.The higher the permeability of core is,the better efficiency of oil recovery will be.When injected hyperbranched polymer system into core with water permcability of about 500mD,we can get highest oil recovery at a polymer viscosity of 150 mPa s.In addition,by using the viscoelasticity of retained polymers and the fluid flushing force,we can get higher oil recovery.