Development Of Polymer With Certain Surface Activity For Oil Displacement

Chemical flooding is the essential stage in the middle and later period of waterflood oil reservoir and the compound flooding is one of the oil displacement technique which is widely used in chemical flooding technology and has successful precedent.The compound flooding can give full play to the spreading of the sweep efficiency and synergy,but chromatographic separation effect can limit its large-scale application.As a kind of polymer flooding,Surface activity of the polymer has great development potential without chromatographic separation phenomenon in oil field.But in terms of molecular structure design,the lack of attention to excellent heat and salt resistance against harsh reservoir characteristics makes the synthesis of surface active polymer difficult to meet the demand of reservoir environment.Therefore,in this paper,the polymer molecular structure is designed for the improvement of activity of surface while giving consideration to the temperature and salt resistance to synthesize target compound and study the solution properties and the feasibility of oil displacement.The work of this thesis includes the following:1.In the design of polymer molecular structure,in order to improve the activity of surface while giving consideration to the temperature and salt resistance,long chain alkyl and benzene sulfonate groups are introduced to improve the surface activity,the benzene ring in the benzene sulfonic acid groups improves the heat resistance and sulfonic acid group improves salt resistance.2.The development and characterization of surface active monomer polymerization:synthesize the surface active monomer polymerization through the "three-step" method,at the same time,apply the FT-IR,1HNMR for the determination of characterization and surface activity of the monomer,interfacial tension reaches minimum 3.12 mN/m,at the concentration of 250 mg/L.3.Synthesis and characterization of Surface active polymer:The optimal synthesis conditions are determined by single factor and orthogonal designs:total monomer concentration is 25%,amount of initiator is 0.2%,AM:AA=6.5:3.5,pH=7.2,reaction temperature is 41 ?,functional monomer amount is 0.3%.Using FT-IR?1HNMR of representation,confirmed the principle of the design are met.Using the dynamic(static)state laser scattering instrument to determine the molecular weight Mw=4.2×106 g/mol,swing radius Rg=170 nm,1500 mg/L hydrodynamic radius of Rh=196 nm.4.Surface active polymer solution performance evaluation:Good solubility,dissolved time is in the 2 h under the condition of high temperature or high salinity.With decreasing interfacial tension ability and emulsifying ability,the interfacial tension of the minimum value is 15.07 mN/m,the lowest rate of water is 8.97%.Good adhesion properties,the viscosity of surface active polymer is 672.3 mPa·s at 70 ? and the concentration is 3000 mg/L.Good temperature tolerance and salt resistance and stable performance,the viscosity of surface active polymer is 120.1 mPa-s at 90 ?;Under different salinity,surface active polymer viscosity was higher than that of HP AM;60 d surface active polymer viscosity retention rate as high as 80%.At the same time,the surface active polymer shows the characteristics of Newtonian fluid,at an low shear rate,while performs the characteristics of non-Newtonian fluid at an high shear rate;the surface active polymer is with the viscosity as the main when the scanning frequency is within the range of Hz 0.01?2 Hz;and when more than 2 Hz,it is elastic based.5.Displacement experimental study:prepare 1500 mg/L surfactant polymer solution with simulated formation water,injection problem existing in condition that permeability is less than 90×10-3 ?m2.But possesses good injection and conductivity in porous media with permeability in 320?3220 ×10-3 ?m2 and establishes high resistance coefficient and residual resistance coefficient,which can improve the recovery rate by more than 16%in the porous media.