Experimental investigation of colloidal silica nanoparticles (C-SNPs) for fines migration control application

Abstract

Formation damage due to fines migration is among the root causes for hydrocarbon productivity decline. This occurs due to minerals dislodging when reservoir fluid flow beyond critical velocity and by poor cementation after acid stimulation activities. Conventional chemical methods have been widely used to prevent the fines migration, however, most of the chemical stabilizer is less robust, functional based on composition of exchangeable cations in rock minerals, cause temporary stabilization and are not environmentally friendly. This paper explores the potential of colloidal silica nanoparticles (C-SNPs) as new solution for fines migration control application. A series of critical velocity core flooding experiments has been carried out to determine the C-SNPs efficiency in enhancing the critical velocity at various temperatures. Berea Buff cores pre-treated with 0.05% C-SNPs (35 nm), were exposed to elevated injection rates. Synthetic formation brine was injected via alternating increasing and return to baseline rate from 0.5 to 41.5 mL/min. The stabilize pressure drops generated during brine injection after C-SNPs injection were used to establish the baseline permeability, kw. The stabilized pressure drops generated after each elevated rate were calculated to determine the permeability, k (at 0.5 mL/min) and to establish the k/kw graph plot. The critical rate’s value was obtained when permeability reduction occurred in the range from 10 to 20% from the initial permeability value. Microscopic visualization using FESEM of the treated cores showed traces of nanoparticles on the core surface and surface modification by surface roughness measurement via atomic surface microscopy (AFM). The permeability of all treated cores remained constant up to 5 mL/min. At 8.3 mL/min and above, variation in permeability was observed caused by fines mobilization but with no significant permeability drops up to 41.5 mL/min. Modification of pore walls and fines surfaces by nanoparticles attachment was described by low surface roughness. The attraction of fines particles on the pore wall and within the particles themselves had strengthened surface morphology, therefore, their detachment and mobilization in porous media were not seen when exposed to high injection velocity.