Particle deposition and mobilisation during deep bed filtration in oilfields
Deposition of latex microspheres on a borosilicate filter was carried out at gradually decreasing suspension velocities at conditions favourable for particle attachment and excluding particle retention due to size exclusion. Particle critical retention concentration followed quadratic function of suspension velocity agreeing with the modified particle attachment/detachment model based on mechanical equilibrium of a particle located on the porous matrix surface within experimental uncertainty in the entire range of studied velocities. Electrostatic force is the dominant factor in a strong particle-matrix attraction. Significant part of latex particles were able to overcome a low energy barrier and be trapped irreversibly in the primary energy minimum. The remaining deposited particles were attached in the secondary energy minimum. Due to a strong particle attraction to the surface, their detachment cannot be achieved by increasing fluid velocity only. Almost a fifth of the attached particles were removed after the reduction of salinity and increase in pH of solution.
Keywords: particle deposition, particle mobilisation, latex microspheres, borosilicate filter, primary energy minimum, secondary energy minimum, DLVO potential, deep bed filtration