环境响应自降解聚合物纳米驱油剂的制备及性能OA

Traditional inorganic nano-flooding agents have been extensively explored for enhanced oil recovery in unconventional low-permeability reservoirs,owing to their unique size effect and interfacial regulation capacity.Yet their intrinsic non-degradable nature frequently causes irreversible pore plugging and permanent formation damage,which severely restricts their large-scale and sustainable application in oilfields.To address this critical technical bottleneck,an environmentally responsive self-degradable polymeric nano-flooding agent,namely polydopamine(PDA)nanoparticles,was rationally constructed.The micromorphology,particle size distribution,surface Zeta potential,and molecular structure of the as-prepared PDA nanoparticles were systematically characterized via SEM,Zeta potential,and FTIR.Subsequently,comprehensive performance evaluations were systematically conducted,including tests on aqueous dispersion stability,oil-water interfacial tension reduction capacity,wettability alteration performance on rock surfaces,temperature/pH-responsive self-degradation behavior,formation protection property,and core-scale oil displacement efficiency,to clarify the application feasibility and targeted optimization direction of PDA nanoparticles as an eco-friendly nano-flooding agent.The experimental results show that PDA nanoparticles can be facilely fabricated by means of solution oxidative self-polymerization,with abundant reactive functional groups on their surface.The nanoparticles exhibit moderate tolerance to monovalent Na+with a critical applicable salinity of approximately 11 688 mg/L in NaCl solution,but are highly sensitive to divalent Ca2+,which indicates that their long-term dispersion stability in high-salinity reservoirs requires further improvement via targeted surface functional modification.PDA nanoparticles exhibit favorable interfacial activity and wettability regulation capacity.At a mass fraction of 0.10%,the nanoparticles reduce the interfacial tension of the toluene/water system by 37.7%and increase the underwater oil contact angle of a strongly lipophilic rock surface from 30.6° to 84.7°,which thereby achieves a wettability transition from strongly lipophilic to nearly neutral wetting.Furthermore,PDA nanoparticles feature distinct dual temperature-and pH-responsive self-degradation properties,which can meet the stability requirements of solution preparation and surface injection at room temperature,and achieve complete degradation under target reservoir conditions to fundamentally eliminate the risk of permanent formation damage.Core flooding tests confirm that PDA nanoparticles can enhance oil recovery of low-permeability cores by more than 6%,with a core permeability damage rate lower than 10%after complete degradation.This work provides a new insight for the development of low-damage,high-efficiency nano-flooding agents,and offers solid experimental support.