摘要
Enhancing oil recovery from clayey reservoirs is a significant challenge in petroleum industry due to complex interactions between fluids and rock surfaces,particularly clay swelling.This study presents the first empirical analysis of magnetic fields'impact on fluid flow in clayey porous media.Our core findings indicate that magnetic treatment of water increases oil recovery by an average of 15–30%in clayey media,with limited effectiveness in pure quartz media.Detailed experiments unraveled that improved recovery factor by magnetic treatment stem from both mitigated swelling and altered magnetic properties at clay surface;introducing 30%clay to porous medium decreased the recovery by 32%compared to pure quartz sand.Heating the clay to around 1000°C to reduce its swelling property improved the recovery by only 16%,suggesting magnetic treatment is not solely attributed to clay swelling mitigation.Treating ferromagnetic films at clay surface with HCl to produce non-magnetic FeCl_(3) resulted in a high recovery factor,similar to the clay-free medium.Moreover,it was determined that a magnetic field intensity of 43760–51740 A/m is optimal for fluid displacement in clayey media.Notably,the intensity of 47760 A/m increased recovery to 84.5%in a 30%clay medium,compared to 49.7%without treatment.Interestingly,it was observed that the maximum flow rate was associated with zero potential difference across the medium,providing a faster method to determine the optimum magnetic field intensity.Lastly,the concept of‘Magnetic memory’was investigated,referring to the persistence of magnetic field's influence after its removal.Our findings indicated that pressure build-up time stability lasted 10 days post-treatment,after which water behavior reverts,and clay swelling resumes.This insight into the temporal dynamics of magnetic field application provides a deeper understanding of its long-term impacts on fluid flow in clayey reservoirs.
